A number of CPC features, like retransmission or remote's receive window, are cport-based. In order to prepare for these features, introduce a CPC CPort context structure.

The CPC Host Device module now implements cport_allocate and cport_release callbacks in order to allocate and release these structures when requested by Greybus module.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- Changes in v3: - simplify cpc_hd_cport_allocate so that cport with ID "i"is at offset "i" in cpc_hd->cports array

drivers/greybus/cpc/Makefile | 2 +- drivers/greybus/cpc/cpc.h | 29 +++++++++ drivers/greybus/cpc/cport.c | 37 +++++++++++ drivers/greybus/cpc/host.c | 115 ++++++++++++++++++++++++++++++++++- drivers/greybus/cpc/host.h | 12 ++++ 5 files changed, 193 insertions(+), 2 deletions(-) create mode 100644 drivers/greybus/cpc/cpc.h create mode 100644 drivers/greybus/cpc/cport.c

diff --git a/drivers/greybus/cpc/Makefile b/drivers/greybus/cpc/Makefile index 490982a0ff5..3d50f8c5473 100644 --- a/drivers/greybus/cpc/Makefile +++ b/drivers/greybus/cpc/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0

-gb-cpc-y := host.o +gb-cpc-y := cport.o host.o

# CPC core obj-$(CONFIG_GREYBUS_CPC) += gb-cpc.o diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h new file mode 100644 index 00000000000..3915a7fbc4f --- /dev/null +++ b/drivers/greybus/cpc/cpc.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#ifndef __CPC_H +#define __CPC_H + +#include <linux/device.h> +#include <linux/greybus.h> +#include <linux/types.h> + +/** + * struct cpc_cport - CPC cport + * @id: cport ID + * @cpc_hd: pointer to the CPC host device this cport belongs to + */ +struct cpc_cport { + u16 id; + + struct cpc_host_device *cpc_hd; +}; + +struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask); +void cpc_cport_release(struct cpc_cport *cport); + +int cpc_cport_message_send(struct cpc_cport *cport, struct gb_message *message, gfp_t gfp_mask); + +#endif diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c new file mode 100644 index 00000000000..88bdb2f8182 --- /dev/null +++ b/drivers/greybus/cpc/cport.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#include "cpc.h" +#include "host.h" + +/** + * cpc_cport_alloc() - Allocate and initialize CPC cport. + * @cport_id: cport ID. + * @gfp_mask: GFP mask for allocation. + * + * Return: Pointer to allocated and initialized cpc_cport, or NULL on failure. + */ +struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask) +{ + struct cpc_cport *cport; + + cport = kzalloc(sizeof(*cport), gfp_mask); + if (!cport) + return NULL; + + cport->id = cport_id; + + return cport; +} + +void cpc_cport_release(struct cpc_cport *cport) +{ + kfree(cport); +} + +int cpc_cport_message_send(struct cpc_cport *cport, struct gb_message *message, gfp_t gfp_mask) +{ + return cport->cpc_hd->driver->message_send(cport->cpc_hd, cport->id, message, gfp_mask); +} diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index 80516517ff6..3dda5b06590 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -7,6 +7,7 @@ #include <linux/greybus.h> #include <linux/module.h>

+#include "cpc.h" #include "host.h"

static struct cpc_host_device *gb_hd_to_cpc_hd(struct gb_host_device *hd) @@ -14,12 +15,101 @@ static struct cpc_host_device *gb_hd_to_cpc_hd(struct gb_host_device *hd) return (struct cpc_host_device *)&hd->hd_priv; }

+static struct cpc_cport *cpc_hd_get_cport_unlocked(struct cpc_host_device *cpc_hd, u16 cport_id) +{ + if (cport_id >= ARRAY_SIZE(cpc_hd->cports)) + return NULL; + + return cpc_hd->cports[cport_id]; +} + +static struct cpc_cport *cpc_hd_get_cport(struct cpc_host_device *cpc_hd, u16 cport_id) +{ + struct cpc_cport *cport; + + mutex_lock(&cpc_hd->lock); + cport = cpc_hd_get_cport_unlocked(cpc_hd, cport_id); + mutex_unlock(&cpc_hd->lock); + + return cport; +} + +static int cpc_hd_message_send(struct cpc_host_device *cpc_hd, u16 cport_id, + struct gb_message *message, gfp_t gfp_mask) +{ + struct cpc_cport *cport; + + cport = cpc_hd_get_cport(cpc_hd, cport_id); + if (!cport) { + dev_err(cpc_hd_dev(cpc_hd), "message_send: cport %u not found\n", cport_id); + return -EINVAL; + } + + return cpc_cport_message_send(cport, message, gfp_mask); +} + +static int cpc_hd_cport_allocate(struct cpc_host_device *cpc_hd, int cport_id, unsigned long flags) +{ + struct cpc_cport *cport; + int ret; + + mutex_lock(&cpc_hd->lock); + if (cport_id < 0) { + for (cport_id = 0; cport_id < ARRAY_SIZE(cpc_hd->cports); cport_id++) { + if (cpc_hd->cports[cport_id] == NULL) + break; + } + } + + if (cport_id >= ARRAY_SIZE(cpc_hd->cports)) { + ret = -ENOSPC; + goto unlock; + } + + cport = cpc_hd_get_cport_unlocked(cpc_hd, cport_id); + if (cport) { + ret = -EBUSY; + goto unlock; + } + + cport = cpc_cport_alloc(cport_id, GFP_KERNEL); + if (!cport) { + ret = -ENOMEM; + goto unlock; + } + + cport->cpc_hd = cpc_hd; + + cpc_hd->cports[cport_id] = cport; + ret = cport_id; + +unlock: + mutex_unlock(&cpc_hd->lock); + + return ret; +} + +static void cpc_hd_cport_release(struct cpc_host_device *cpc_hd, u16 cport_id) +{ + struct cpc_cport *cport; + + mutex_lock(&cpc_hd->lock); + + cport = cpc_hd->cports[cport_id]; + if (cport) { + cpc_cport_release(cport); + cpc_hd->cports[cport_id] = NULL; + } + + mutex_unlock(&cpc_hd->lock); +} + static int cpc_gb_message_send(struct gb_host_device *gb_hd, u16 cport_id, struct gb_message *message, gfp_t gfp_mask) { struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd);

- return cpc_hd->driver->message_send(cpc_hd, cport_id, message, gfp_mask); + return cpc_hd_message_send(cpc_hd, cport_id, message, gfp_mask); }

static void cpc_gb_message_cancel(struct gb_message *message) @@ -27,12 +117,33 @@ static void cpc_gb_message_cancel(struct gb_message *message) /* Not implemented */ }

+static int cpc_gb_cport_allocate(struct gb_host_device *gb_hd, int cport_id, unsigned long flags) +{ + struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd); + + return cpc_hd_cport_allocate(cpc_hd, cport_id, flags); +} + +static void cpc_gb_cport_release(struct gb_host_device *gb_hd, u16 cport_id) +{ + struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd); + + return cpc_hd_cport_release(cpc_hd, cport_id); +} + static struct gb_hd_driver cpc_gb_driver = { .hd_priv_size = sizeof(struct cpc_host_device), .message_send = cpc_gb_message_send, .message_cancel = cpc_gb_message_cancel, + .cport_allocate = cpc_gb_cport_allocate, + .cport_release = cpc_gb_cport_release, };

+static void cpc_hd_init(struct cpc_host_device *cpc_hd) +{ + mutex_init(&cpc_hd->lock); +} + struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct device *parent) { struct cpc_host_device *cpc_hd; @@ -51,6 +162,8 @@ struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct devic cpc_hd->gb_hd = hd; cpc_hd->driver = driver;

+ cpc_hd_init(cpc_hd); + return cpc_hd; } EXPORT_SYMBOL_GPL(cpc_hd_create); diff --git a/drivers/greybus/cpc/host.h b/drivers/greybus/cpc/host.h index f55feb303f4..c3f2f56a939 100644 --- a/drivers/greybus/cpc/host.h +++ b/drivers/greybus/cpc/host.h @@ -8,11 +8,13 @@

#include <linux/device.h> #include <linux/greybus.h> +#include <linux/mutex.h> #include <linux/types.h>

#define GB_CPC_MSG_SIZE_MAX 4096 #define GB_CPC_NUM_CPORTS 8

+struct cpc_cport; struct cpc_host_device;

struct cpc_hd_driver { @@ -25,12 +27,22 @@ struct cpc_hd_driver { * struct cpc_host_device - CPC host device. * @gb_hd: pointer to Greybus Host Device this device belongs to. * @driver: driver operations. + * @lock: mutex to synchronize access to cport array. + * @cports: array of cport pointers allocated by Greybus core. */ struct cpc_host_device { struct gb_host_device *gb_hd; const struct cpc_hd_driver *driver; + + struct mutex lock; /* Synchronize access to cports */ + struct cpc_cport *cports[GB_CPC_NUM_CPORTS]; };

+static inline struct device *cpc_hd_dev(struct cpc_host_device *cpc_hd) +{ + return &cpc_hd->gb_hd->dev; +} + struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct device *parent); int cpc_hd_add(struct cpc_host_device *cpc_hd); void cpc_hd_put(struct cpc_host_device *cpc_hd);

Take advantage of the padding bytes present in the Greybus header to store the CPort ID and minimize overhead. This technique is already used by the es2 driver.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- Changes in v2: - clear pad bytes when unpacking CPort ID

drivers/greybus/cpc/cpc.h | 3 +++ drivers/greybus/cpc/cport.c | 34 ++++++++++++++++++++++++++++++++++ drivers/greybus/cpc/host.c | 13 ++++++++++++- drivers/greybus/cpc/host.h | 2 +- 4 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h index d9f8f60913a..62597957814 100644 --- a/drivers/greybus/cpc/cpc.h +++ b/drivers/greybus/cpc/cpc.h @@ -24,6 +24,9 @@ struct cpc_cport { struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask); void cpc_cport_release(struct cpc_cport *cport);

+void cpc_cport_pack(struct gb_operation_msg_hdr *gb_hdr, u16 cport_id); +u16 cpc_cport_unpack(struct gb_operation_msg_hdr *gb_hdr); + int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb);

struct cpc_skb_cb { diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c index ed0b8e8b0d7..2c73d8e724e 100644 --- a/drivers/greybus/cpc/cport.c +++ b/drivers/greybus/cpc/cport.c @@ -3,6 +3,9 @@ * Copyright (c) 2025, Silicon Laboratories, Inc. */

+#include <linux/unaligned.h> +#include <linux/skbuff.h> + #include "cpc.h" #include "host.h"

@@ -31,6 +34,32 @@ void cpc_cport_release(struct cpc_cport *cport) kfree(cport); }

+/** + * cpc_cport_pack() - Pack CPort ID into Greybus Operation Message header. + * @gb_hdr: Greybus operation message header. + * @cport_id: CPort ID to pack. + */ +void cpc_cport_pack(struct gb_operation_msg_hdr *gb_hdr, u16 cport_id) +{ + put_unaligned_le16(cport_id, gb_hdr->pad); +} + +/** + * cpc_cport_unpack() - Unpack CPort ID from Greybus Operation Message header. + * @gb_hdr: Greybus operation message header. + * + * Return: CPort ID packed in the header. + */ +u16 cpc_cport_unpack(struct gb_operation_msg_hdr *gb_hdr) +{ + u16 cport_id = get_unaligned_le16(gb_hdr->pad); + + // Clear padding bytes + put_unaligned_le16(0, gb_hdr->pad); + + return cport_id; +} + /** * cpc_cport_transmit() - Transmit skb over cport. * @cport: cport. @@ -39,6 +68,11 @@ void cpc_cport_release(struct cpc_cport *cport) int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb) { struct cpc_host_device *cpc_hd = cport->cpc_hd; + struct gb_operation_msg_hdr *gb_hdr; + + /* Inject cport ID in Greybus header */ + gb_hdr = (struct gb_operation_msg_hdr *)skb->data; + cpc_cport_pack(gb_hdr, cport->id);

return cpc_hd_send_skb(cpc_hd, skb); } diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index a3acfc9bfca..10b0529dc4e 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -209,8 +209,19 @@ void cpc_hd_message_sent(struct sk_buff *skb, int status) } EXPORT_SYMBOL_GPL(cpc_hd_message_sent);

-void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, u16 cport_id, u8 *data, size_t length) +void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, u8 *data, size_t length) { + struct gb_operation_msg_hdr *gb_hdr; + u16 cport_id; + + /* Prevent an out-of-bound access if called with non-sensical parameters. */ + if (!data || length < sizeof(*gb_hdr)) + return; + + /* Retrieve cport ID that was packed in Greybus header */ + gb_hdr = (struct gb_operation_msg_hdr *)data; + cport_id = cpc_cport_unpack(gb_hdr); + greybus_data_rcvd(cpc_hd->gb_hd, cport_id, data, length); } EXPORT_SYMBOL_GPL(cpc_hd_rcvd); diff --git a/drivers/greybus/cpc/host.h b/drivers/greybus/cpc/host.h index 191b5e394a6..2e568bac44e 100644 --- a/drivers/greybus/cpc/host.h +++ b/drivers/greybus/cpc/host.h @@ -45,7 +45,7 @@ struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct devic int cpc_hd_add(struct cpc_host_device *cpc_hd); void cpc_hd_put(struct cpc_host_device *cpc_hd); void cpc_hd_del(struct cpc_host_device *cpc_hd); -void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, u16 cport_id, u8 *data, size_t length); +void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, u8 *data, size_t length); void cpc_hd_message_sent(struct sk_buff *skb, int status);

int cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb);

CPC main features are reliable transmission and remote's receive window management. To implement these features, an additional header is needed. This header is prepended to all Greybus messages before going on the wire.

Reliable transmission: to make transmission reliable, messages are sequenced and acknowledged. That constitutes two bytes of the header, one for the sequence number, one for the acknowledgment number. If a message is not acked in a timely manner, a retransmission mechanism will attempt another transmission. That mechanism will be implemented in a future patch set.

Remote's receive window: the remote advertises the number of reception buffers that are available on this cport. The other peer must take care of not sending more messages than advertised by the remote. This is a sort of flow control. That accounts for one byte in the header.

The remaining byte carries some flags. For instance, there is a flag to indicate if it's a CPC message or a Greybus message.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- Changes in v3: - remove CPC_HEADER_SIZE and GREYBUS_HEADER_SIZE macros

Changes in v2: - Minor tweaks to structure documentation

drivers/greybus/cpc/header.h | 41 ++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 drivers/greybus/cpc/header.h

diff --git a/drivers/greybus/cpc/header.h b/drivers/greybus/cpc/header.h new file mode 100644 index 00000000000..f65a608a650 --- /dev/null +++ b/drivers/greybus/cpc/header.h @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#ifndef __CPC_HEADER_H +#define __CPC_HEADER_H + +#include <linux/greybus.h> +#include <linux/types.h> + +#define CPC_HEADER_MAX_RX_WINDOW U8_MAX + +/** + * struct cpc header - Representation of CPC header. + * @ctrl_flags: contains the type of frame and other control flags. + * @recv_wnd: number of buffers that the cport can receive without blocking. + * @seq: sequence number. + * @ack: acknowledge number, indicate to the remote the next sequence number + * this peer expects to see. + * + * Each peer can confirm reception of frames by setting the acknowledgment number to the next frame + * it expects to see, i.e. setting the ack number to X effectively acknowledges frames with sequence + * number up to X-1. + * + * CPC is designed around the concept that each cport has its pool of reception buffers. The number + * of buffers in a pool is advertised to the remote via the @recv_wnd attribute. This acts as + * software flow-control, and a peer shall not send frames to a remote if the @recv_wnd is zero. + * + * The eighth-bit (0x80) of the control byte indicates if the frame targets CPC or Greybus. If the + * bit is set, the frame should be interpreted as a CPC control frame. For simplicity, control + * frames have the same encoding as Greybus frames. + */ +struct cpc_header { + __u8 ctrl_flags; + __u8 recv_wnd; + __u8 seq; + __u8 ack; +} __packed; + +#endif

The first step in making the CPC header actually do something is to add the sequence number to outgoing messages and validate that incoming frames are received in order.

At this stage, the driver doesn't send standalone acks, so if a message with Sequence X is received, the remote will not be acknowledged until a message targeting that CPort comes from the Greybus layer. Only then the driver will ack with acknowledgedment number of X + 1.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- drivers/greybus/cpc/Makefile | 2 +- drivers/greybus/cpc/cpc.h | 20 +++++++++++++++ drivers/greybus/cpc/cport.c | 25 ++++++++++++++++++ drivers/greybus/cpc/header.c | 17 ++++++++++++ drivers/greybus/cpc/header.h | 2 ++ drivers/greybus/cpc/host.c | 13 +++++++--- drivers/greybus/cpc/protocol.c | 47 ++++++++++++++++++++++++++++++++++ 7 files changed, 121 insertions(+), 5 deletions(-) create mode 100644 drivers/greybus/cpc/header.c create mode 100644 drivers/greybus/cpc/protocol.c

diff --git a/drivers/greybus/cpc/Makefile b/drivers/greybus/cpc/Makefile index 3d50f8c5473..c4b530d27a3 100644 --- a/drivers/greybus/cpc/Makefile +++ b/drivers/greybus/cpc/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0

-gb-cpc-y := cport.o host.o +gb-cpc-y := cport.o header.o host.o protocol.o

# CPC core obj-$(CONFIG_GREYBUS_CPC) += gb-cpc.o diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h index 62597957814..87b54a4fd34 100644 --- a/drivers/greybus/cpc/cpc.h +++ b/drivers/greybus/cpc/cpc.h @@ -8,17 +8,32 @@

#include <linux/device.h> #include <linux/greybus.h> +#include <linux/mutex.h> #include <linux/types.h>

+struct sk_buff; + /** * struct cpc_cport - CPC cport * @id: cport ID * @cpc_hd: pointer to the CPC host device this cport belongs to + * @lock: mutex to synchronize accesses to tcb and other attributes + * @tcb: Transmission Control Block */ struct cpc_cport { u16 id;

struct cpc_host_device *cpc_hd; + struct mutex lock; /* Synchronize access to state variables */ + + /* + * @ack: current acknowledge number + * @seq: current sequence number + */ + struct { + u8 ack; + u8 seq; + } tcb; };

struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask); @@ -34,8 +49,13 @@ struct cpc_skb_cb {

/* Keep track of the GB message the skb originates from */ struct gb_message *gb_message; + + u8 seq; };

#define CPC_SKB_CB(__skb) ((struct cpc_skb_cb *)&((__skb)->cb[0]))

+void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack); +void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb); + #endif diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c index 2c73d8e724e..7041a6a8a36 100644 --- a/drivers/greybus/cpc/cport.c +++ b/drivers/greybus/cpc/cport.c @@ -9,6 +9,16 @@ #include "cpc.h" #include "host.h"

+/** + * cpc_cport_tcb_reset() - Reset cport's TCB to initial values. + * @cport: cport pointer + */ +static void cpc_cport_tcb_reset(struct cpc_cport *cport) +{ + cport->tcb.ack = 0; + cport->tcb.seq = 0; +} + /** * cpc_cport_alloc() - Allocate and initialize CPC cport. * @cport_id: cport ID. @@ -25,6 +35,9 @@ struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask) return NULL;

cport->id = cport_id; + cpc_cport_tcb_reset(cport); + + mutex_init(&cport->lock);

return cport; } @@ -69,10 +82,22 @@ int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb) { struct cpc_host_device *cpc_hd = cport->cpc_hd; struct gb_operation_msg_hdr *gb_hdr; + u8 ack;

/* Inject cport ID in Greybus header */ gb_hdr = (struct gb_operation_msg_hdr *)skb->data; cpc_cport_pack(gb_hdr, cport->id);

+ mutex_lock(&cport->lock); + + CPC_SKB_CB(skb)->seq = cport->tcb.seq; + + cport->tcb.seq++; + ack = cport->tcb.ack; + + mutex_unlock(&cport->lock); + + cpc_protocol_prepare_header(skb, ack); + return cpc_hd_send_skb(cpc_hd, skb); } diff --git a/drivers/greybus/cpc/header.c b/drivers/greybus/cpc/header.c new file mode 100644 index 00000000000..62946d6077e --- /dev/null +++ b/drivers/greybus/cpc/header.c @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#include "header.h" + +/** + * cpc_header_get_seq() - Get the sequence number. + * @hdr: CPC header. + * + * Return: Sequence number. + */ +u8 cpc_header_get_seq(const struct cpc_header *hdr) +{ + return hdr->seq; +} diff --git a/drivers/greybus/cpc/header.h b/drivers/greybus/cpc/header.h index f65a608a650..5196422380e 100644 --- a/drivers/greybus/cpc/header.h +++ b/drivers/greybus/cpc/header.h @@ -38,4 +38,6 @@ struct cpc_header { __u8 ack; } __packed;

+u8 cpc_header_get_seq(const struct cpc_header *hdr); + #endif diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index 759322759bd..2c1b5d02ec2 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -215,19 +215,24 @@ EXPORT_SYMBOL_GPL(cpc_hd_message_sent); void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, struct sk_buff *skb) { struct gb_operation_msg_hdr *gb_hdr; + struct cpc_cport *cport; u16 cport_id;

/* Prevent an out-of-bound access if called with non-sensical parameters. */ if (skb->len < (sizeof(*gb_hdr) + sizeof(struct cpc_header))) goto free_skb;

- skb_pull(skb, sizeof(struct cpc_header)); - /* Retrieve cport ID that was packed in Greybus header */ - gb_hdr = (struct gb_operation_msg_hdr *)skb->data; + gb_hdr = (struct gb_operation_msg_hdr *)(skb->data + sizeof(struct cpc_header)); cport_id = cpc_cport_unpack(gb_hdr);

- greybus_data_rcvd(cpc_hd->gb_hd, cport_id, skb->data, skb->len); + cport = cpc_hd_get_cport(cpc_hd, cport_id); + if (!cport) { + dev_warn(cpc_hd_dev(cpc_hd), "cport %u not allocated\n", cport_id); + goto free_skb; + } + + cpc_protocol_on_data(cport, skb);

free_skb: kfree_skb(skb); diff --git a/drivers/greybus/cpc/protocol.c b/drivers/greybus/cpc/protocol.c new file mode 100644 index 00000000000..8f0ac6dfa11 --- /dev/null +++ b/drivers/greybus/cpc/protocol.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#include <linux/skbuff.h> + +#include "cpc.h" +#include "header.h" +#include "host.h" + +void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack) +{ + struct cpc_header *hdr; + + skb_push(skb, sizeof(*hdr)); + + hdr = (struct cpc_header *)skb->data; + memset(hdr, 0, sizeof(*hdr)); + + hdr->ack = ack; + hdr->seq = CPC_SKB_CB(skb)->seq; +} + +void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb) +{ + struct cpc_header *cpc_hdr = (struct cpc_header *)skb->data; + u8 seq = cpc_header_get_seq(cpc_hdr); + bool expected_seq = false; + + mutex_lock(&cport->lock); + + expected_seq = seq == cport->tcb.ack; + if (expected_seq) + cport->tcb.ack++; + else + dev_warn_ratelimited(cpc_hd_dev(cport->cpc_hd), + "unexpected seq: %u, expected seq: %u\n", seq, cport->tcb.ack); + + mutex_unlock(&cport->lock); + + if (expected_seq) { + skb_pull(skb, sizeof(*cpc_hdr)); + + greybus_data_rcvd(cport->cpc_hd->gb_hd, cport->id, skb->data, skb->len); + } +}

A feature of CPC is the RX window. This value, advertised in every packet, indicates to the remote peer how many reception buffers are available for that CPort. The remote peer must not send more messages than advertised, as these extra messages are almost guaranteed to be dropped by the receiver. This is a bit similar to TCP's receive window, but expressed in a number of messages instead of bytes.

As the first step to handle remote's RX window, store the skb in a sk_buff_head list, instead of sending a message immediately when pushed by Greybus. skbs are still sent out straight away for now, but a future commit will make sure they stay in the holding queue instead of being sent out immediately if the remote's RX window is too small.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- drivers/greybus/cpc/cpc.h | 10 ++++++---- drivers/greybus/cpc/cport.c | 21 ++++++++++++--------- drivers/greybus/cpc/host.c | 4 +++- drivers/greybus/cpc/protocol.c | 25 ++++++++++++++++++++++++- 4 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h index 725fd7f4afc..f1669585c45 100644 --- a/drivers/greybus/cpc/cpc.h +++ b/drivers/greybus/cpc/cpc.h @@ -9,15 +9,15 @@ #include <linux/device.h> #include <linux/greybus.h> #include <linux/mutex.h> +#include <linux/skbuff.h> #include <linux/types.h>

-struct sk_buff; - /** * struct cpc_cport - CPC cport * @id: cport ID * @cpc_hd: pointer to the CPC host device this cport belongs to * @lock: mutex to synchronize accesses to tcb and other attributes + * @holding_queue: list of frames queued to be sent * @tcb: Transmission Control Block */ struct cpc_cport { @@ -26,6 +26,8 @@ struct cpc_cport { struct cpc_host_device *cpc_hd; struct mutex lock; /* Synchronize access to state variables */

+ struct sk_buff_head holding_queue; + /* * @ack: current acknowledge number * @seq: current sequence number @@ -42,7 +44,7 @@ void cpc_cport_release(struct cpc_cport *cport); void cpc_cport_pack(struct gb_operation_msg_hdr *gb_hdr, u16 cport_id); u16 cpc_cport_unpack(struct gb_operation_msg_hdr *gb_hdr);

-int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb); +void cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb);

struct cpc_skb_cb { struct cpc_cport *cport; @@ -58,7 +60,7 @@ struct cpc_skb_cb {

#define CPC_SKB_CB(__skb) ((struct cpc_skb_cb *)&((__skb)->cb[0]))

-void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack); void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb); +void __cpc_protocol_write_head(struct cpc_cport *cport);

#endif diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c index 847cc8ebe41..91c39856e22 100644 --- a/drivers/greybus/cpc/cport.c +++ b/drivers/greybus/cpc/cport.c @@ -7,7 +7,6 @@ #include <linux/skbuff.h>

#include "cpc.h" -#include "host.h"

/** * cpc_cport_tcb_reset() - Reset cport's TCB to initial values. @@ -38,15 +37,23 @@ struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask) cpc_cport_tcb_reset(cport);

mutex_init(&cport->lock); + skb_queue_head_init(&cport->holding_queue);

return cport; }

void cpc_cport_release(struct cpc_cport *cport) { + skb_queue_purge(&cport->holding_queue); kfree(cport); }

+static void cpc_cport_queue_skb(struct cpc_cport *cport, struct sk_buff *skb) +{ + __skb_header_release(skb); + __skb_queue_tail(&cport->holding_queue, skb); +} + /** * cpc_cport_pack() - Pack CPort ID into Greybus Operation Message header. * @gb_hdr: Greybus operation message header. @@ -78,11 +85,9 @@ u16 cpc_cport_unpack(struct gb_operation_msg_hdr *gb_hdr) * @cport: cport. * @skb: skb to be transmitted. */ -int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb) +void cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb) { - struct cpc_host_device *cpc_hd = cport->cpc_hd; struct gb_operation_msg_hdr *gb_hdr; - u8 ack;

/* Inject cport ID in Greybus header */ gb_hdr = (struct gb_operation_msg_hdr *)skb->data; @@ -94,11 +99,9 @@ int cpc_cport_transmit(struct cpc_cport *cport, struct sk_buff *skb) CPC_SKB_CB(skb)->cpc_flags = CPC_SKB_FLAG_REQ_ACK;

cport->tcb.seq++; - ack = cport->tcb.ack; + + cpc_cport_queue_skb(cport, skb); + __cpc_protocol_write_head(cport);

mutex_unlock(&cport->lock); - - cpc_protocol_prepare_header(skb, ack); - - return cpc_hd_send_skb(cpc_hd, skb); } diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index 2c1b5d02ec2..225f9342cd2 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -62,7 +62,9 @@ static int cpc_hd_message_send(struct cpc_host_device *cpc_hd, u16 cport_id, CPC_SKB_CB(skb)->cport = cport; CPC_SKB_CB(skb)->gb_message = message;

- return cpc_cport_transmit(cport, skb); + cpc_cport_transmit(cport, skb); + + return 0; }

static int cpc_hd_cport_allocate(struct cpc_host_device *cpc_hd, int cport_id, unsigned long flags) diff --git a/drivers/greybus/cpc/protocol.c b/drivers/greybus/cpc/protocol.c index 97db70a53b0..4cda71994d8 100644 --- a/drivers/greybus/cpc/protocol.c +++ b/drivers/greybus/cpc/protocol.c @@ -14,7 +14,7 @@ static bool cpc_skb_is_sequenced(struct sk_buff *skb) return CPC_SKB_CB(skb)->cpc_flags & CPC_SKB_FLAG_REQ_ACK; }

-void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack) +static void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack) { struct cpc_header *hdr;

@@ -86,3 +86,26 @@ void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb) greybus_data_rcvd(cport->cpc_hd->gb_hd, cport->id, skb->data, skb->len); } } + +static void __cpc_protocol_write_skb(struct cpc_cport *cport, struct sk_buff *skb, u8 ack) +{ + cpc_protocol_prepare_header(skb, ack); + + cpc_hd_send_skb(cport->cpc_hd, skb); +} + +/* Write skbs at the head of holding queue */ +void __cpc_protocol_write_head(struct cpc_cport *cport) +{ + struct sk_buff *skb; + u8 ack; + + ack = cport->tcb.ack; + + /* For each SKB in the holding queue, clone it and pass it to lower layer */ + while ((skb = skb_peek(&cport->holding_queue))) { + skb_unlink(skb, &cport->holding_queue); + + __cpc_protocol_write_skb(cport, skb, ack); + } +}

The RX window indicates how many reception buffers the peer has available for that cport. The other peer must not send more messages than that window, or the chances of those messages being lost is very high, leading to retransmissions and poor performance.

The RX window is associated with the ack number, and indicates the valid range of sequence number the other peer can use:

Ack RX window Valid Sequence Range

X 0 None X 1 X X 2 X -> X+1

So everytime an ack is received, the driver evaluates if the valid sequence range has changed and if so pops message from its holding queue.

SKBs used to be passed directly to the driver for transmission. Now SBKs still need to be passed to driver for transmission, but CPC also needs to keep track of them, to be able to trigger a retransmission if they are not acked in a timely manner. As SKBs cannot be in two lists at the same time, drivers now get cloned SKBs.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- Changes in v2: - fix documentation of cpc_header_number_in_window which documented a unexisting parameter `end` - simplify implementation of cpc_header_get_frames_acked_count

drivers/greybus/cpc/cpc.h | 9 ++++ drivers/greybus/cpc/cport.c | 5 +++ drivers/greybus/cpc/header.c | 78 ++++++++++++++++++++++++++++++++++ drivers/greybus/cpc/header.h | 6 +++ drivers/greybus/cpc/host.c | 9 ---- drivers/greybus/cpc/host.h | 1 - drivers/greybus/cpc/protocol.c | 71 ++++++++++++++++++++++++++++--- 7 files changed, 163 insertions(+), 16 deletions(-)

diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h index f1669585c45..e8cbe916630 100644 --- a/drivers/greybus/cpc/cpc.h +++ b/drivers/greybus/cpc/cpc.h @@ -18,6 +18,7 @@ * @cpc_hd: pointer to the CPC host device this cport belongs to * @lock: mutex to synchronize accesses to tcb and other attributes * @holding_queue: list of frames queued to be sent + * @retx_queue: list of frames sent and waiting for acknowledgment * @tcb: Transmission Control Block */ struct cpc_cport { @@ -27,12 +28,20 @@ struct cpc_cport { struct mutex lock; /* Synchronize access to state variables */

struct sk_buff_head holding_queue; + struct sk_buff_head retx_queue;

/* + * @send_wnd: send window, maximum number of frames that the remote can accept. + * TX frames should have a sequence in the range [send_una; send_una + send_wnd] + * @send_nxt: send next, the next sequence number that will be used for transmission + * @send_una: send unacknowledged, the oldest unacknowledged sequence number * @ack: current acknowledge number * @seq: current sequence number */ struct { + u8 send_wnd; + u8 send_nxt; + u8 send_una; u8 ack; u8 seq; } tcb; diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c index 91c39856e22..c05d89709f0 100644 --- a/drivers/greybus/cpc/cport.c +++ b/drivers/greybus/cpc/cport.c @@ -16,6 +16,9 @@ static void cpc_cport_tcb_reset(struct cpc_cport *cport) { cport->tcb.ack = 0; cport->tcb.seq = 0; + cport->tcb.send_nxt = 0; + cport->tcb.send_una = 0; + cport->tcb.send_wnd = 1; }

/** @@ -38,12 +41,14 @@ struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask)

mutex_init(&cport->lock); skb_queue_head_init(&cport->holding_queue); + skb_queue_head_init(&cport->retx_queue);

return cport; }

void cpc_cport_release(struct cpc_cport *cport) { + skb_queue_purge(&cport->retx_queue); skb_queue_purge(&cport->holding_queue); kfree(cport); } diff --git a/drivers/greybus/cpc/header.c b/drivers/greybus/cpc/header.c index 8875a6fed26..dfcd5581133 100644 --- a/drivers/greybus/cpc/header.c +++ b/drivers/greybus/cpc/header.c @@ -22,6 +22,17 @@ bool cpc_header_is_control(const struct cpc_header *hdr) return hdr->ctrl_flags & CPC_HEADER_CONTROL_IS_CONTROL_MASK; }

+/** + * cpc_header_get_recv_wnd() - Get the receive window. + * @hdr: CPC header. + * + * Return: Receive window. + */ +u8 cpc_header_get_recv_wnd(const struct cpc_header *hdr) +{ + return hdr->recv_wnd; +} + /** * cpc_header_get_seq() - Get the sequence number. * @hdr: CPC header. @@ -33,6 +44,17 @@ u8 cpc_header_get_seq(const struct cpc_header *hdr) return hdr->seq; }

+/** + * cpc_header_get_ack() - Get the acknowledge number. + * @hdr: CPC header. + * + * Return: Acknowledge number. + */ +u8 cpc_header_get_ack(const struct cpc_header *hdr) +{ + return hdr->ack; +} + /** * cpc_header_get_req_ack() - Get the request acknowledge frame flag. * @hdr: CPC header. @@ -56,3 +78,59 @@ u8 cpc_header_encode_ctrl_flags(bool control, bool req_ack) return FIELD_PREP(CPC_HEADER_CONTROL_IS_CONTROL_MASK, control) | FIELD_PREP(CPC_HEADER_CONTROL_REQ_ACK_MASK, req_ack); } + +/** + * cpc_header_get_frames_acked_count() - Get frames to be acknowledged. + * @seq: Current sequence number of the endpoint. + * @ack: Acknowledge number of the received frame. + * + * Return: Frames to be acknowledged. + */ +u8 cpc_header_get_frames_acked_count(u8 seq, u8 ack) +{ + return ack - seq; +} + +/** + * cpc_header_number_in_window() - Test if a number is within a window. + * @start: Start of the window. + * @wnd: Window size. + * @n: Number to be tested. + * + * Given the start of the window and its size, test if the number is + * in the range [start; start + wnd). + * + * @return True if start <= n <= start + wnd - 1 (modulo 256), otherwise false. + */ +bool cpc_header_number_in_window(u8 start, u8 wnd, u8 n) +{ + u8 end; + + if (wnd == 0) + return false; + + end = start + wnd - 1; + + return cpc_header_number_in_range(start, end, n); +} + +/** + * cpc_header_number_in_range() - Test if a number is between start and end (included). + * @start: Lowest limit. + * @end: Highest limit inclusively. + * @n: Number to be tested. + * + * @return True if start <= n <= end (modulo 256), otherwise false. + */ +bool cpc_header_number_in_range(u8 start, u8 end, u8 n) +{ + if (end >= start) { + if (n < start || n > end) + return false; + } else { + if (n > end && n < start) + return false; + } + + return true; +} diff --git a/drivers/greybus/cpc/header.h b/drivers/greybus/cpc/header.h index 19612012b19..906bf45660d 100644 --- a/drivers/greybus/cpc/header.h +++ b/drivers/greybus/cpc/header.h @@ -39,8 +39,14 @@ struct cpc_header { } __packed;

bool cpc_header_is_control(const struct cpc_header *hdr); +u8 cpc_header_get_recv_wnd(const struct cpc_header *hdr); u8 cpc_header_get_seq(const struct cpc_header *hdr); +u8 cpc_header_get_ack(const struct cpc_header *hdr); bool cpc_header_get_req_ack(const struct cpc_header *hdr); u8 cpc_header_encode_ctrl_flags(bool control, bool req_ack);

+u8 cpc_header_get_frames_acked_count(u8 seq, u8 ack); +bool cpc_header_number_in_window(u8 start, u8 wnd, u8 n); +bool cpc_header_number_in_range(u8 start, u8 end, u8 n); + #endif diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index 225f9342cd2..9a0f8158504 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -205,15 +205,6 @@ void cpc_hd_del(struct cpc_host_device *cpc_hd) } EXPORT_SYMBOL_GPL(cpc_hd_del);

-void cpc_hd_message_sent(struct sk_buff *skb, int status) -{ - struct cpc_host_device *cpc_hd = CPC_SKB_CB(skb)->cport->cpc_hd; - struct gb_host_device *hd = cpc_hd->gb_hd; - - greybus_message_sent(hd, CPC_SKB_CB(skb)->gb_message, status); -} -EXPORT_SYMBOL_GPL(cpc_hd_message_sent); - void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, struct sk_buff *skb) { struct gb_operation_msg_hdr *gb_hdr; diff --git a/drivers/greybus/cpc/host.h b/drivers/greybus/cpc/host.h index cc835f5298b..8f05877b2be 100644 --- a/drivers/greybus/cpc/host.h +++ b/drivers/greybus/cpc/host.h @@ -46,7 +46,6 @@ int cpc_hd_add(struct cpc_host_device *cpc_hd); void cpc_hd_put(struct cpc_host_device *cpc_hd); void cpc_hd_del(struct cpc_host_device *cpc_hd); void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, struct sk_buff *skb); -void cpc_hd_message_sent(struct sk_buff *skb, int status);

int cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb);

diff --git a/drivers/greybus/cpc/protocol.c b/drivers/greybus/cpc/protocol.c index 4cda71994d8..4afaf0eb95f 100644 --- a/drivers/greybus/cpc/protocol.c +++ b/drivers/greybus/cpc/protocol.c @@ -14,7 +14,7 @@ static bool cpc_skb_is_sequenced(struct sk_buff *skb) return CPC_SKB_CB(skb)->cpc_flags & CPC_SKB_FLAG_REQ_ACK; }

-static void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack) +static void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack, u8 recv_window) { struct cpc_header *hdr;

@@ -24,6 +24,7 @@ static void cpc_protocol_prepare_header(struct sk_buff *skb, u8 ack) memset(hdr, 0, sizeof(*hdr));

hdr->ack = ack; + hdr->recv_wnd = recv_window; hdr->seq = CPC_SKB_CB(skb)->seq; hdr->ctrl_flags = cpc_header_encode_ctrl_flags(!CPC_SKB_CB(skb)->gb_message, cpc_skb_is_sequenced(skb)); @@ -47,11 +48,47 @@ static void cpc_protocol_queue_ack(struct cpc_cport *cport, u8 ack) gb_hdr->size = cpu_to_le16(sizeof(*gb_hdr)); cpc_cport_pack(gb_hdr, cport->id);

- cpc_protocol_prepare_header(skb, ack); + cpc_protocol_prepare_header(skb, ack, CPC_HEADER_MAX_RX_WINDOW);

cpc_hd_send_skb(cport->cpc_hd, skb); }

+static void __cpc_protocol_receive_ack(struct cpc_cport *cport, u8 recv_wnd, u8 ack) +{ + struct gb_host_device *gb_hd = cport->cpc_hd->gb_hd; + struct sk_buff *skb; + u8 acked_frames; + + cport->tcb.send_wnd = recv_wnd; + + skb = skb_peek(&cport->retx_queue); + if (!skb) + return; + + /* Return if no frame to ACK. */ + if (!cpc_header_number_in_range(cport->tcb.send_una, cport->tcb.send_nxt, ack)) + return; + + /* Calculate how many frames will be ACK'd. */ + acked_frames = cpc_header_get_frames_acked_count(CPC_SKB_CB(skb)->seq, ack); + + for (u8 i = 0; i < acked_frames; i++) { + skb = skb_dequeue(&cport->retx_queue); + if (!skb) { + dev_err_ratelimited(cpc_hd_dev(cport->cpc_hd), + "pending ack queue shorter than expected"); + break; + } + + if (CPC_SKB_CB(skb)->gb_message) + greybus_message_sent(gb_hd, CPC_SKB_CB(skb)->gb_message, 0); + + kfree_skb(skb); + + cport->tcb.send_una++; + } +} + void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb) { struct cpc_header *cpc_hdr = (struct cpc_header *)skb->data; @@ -62,6 +99,9 @@ void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb)

mutex_lock(&cport->lock);

+ __cpc_protocol_receive_ack(cport, cpc_header_get_recv_wnd(cpc_hdr), + cpc_header_get_ack(cpc_hdr)); + if (require_ack) { expected_seq = seq == cport->tcb.ack; if (expected_seq) @@ -74,6 +114,8 @@ void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb)

ack = cport->tcb.ack;

+ __cpc_protocol_write_head(cport); + mutex_unlock(&cport->lock);

/* Ack no matter if the sequence was valid or not, to resync with remote */ @@ -87,9 +129,10 @@ void cpc_protocol_on_data(struct cpc_cport *cport, struct sk_buff *skb) } }

-static void __cpc_protocol_write_skb(struct cpc_cport *cport, struct sk_buff *skb, u8 ack) +static void __cpc_protocol_write_skb(struct cpc_cport *cport, struct sk_buff *skb, u8 ack, + u8 recv_window) { - cpc_protocol_prepare_header(skb, ack); + cpc_protocol_prepare_header(skb, ack, recv_window);

cpc_hd_send_skb(cport->cpc_hd, skb); } @@ -98,14 +141,30 @@ static void __cpc_protocol_write_skb(struct cpc_cport *cport, struct sk_buff *sk void __cpc_protocol_write_head(struct cpc_cport *cport) { struct sk_buff *skb; - u8 ack; + u8 ack, send_una, send_wnd;

ack = cport->tcb.ack; + send_una = cport->tcb.send_una; + send_wnd = cport->tcb.send_wnd;

/* For each SKB in the holding queue, clone it and pass it to lower layer */ while ((skb = skb_peek(&cport->holding_queue))) { + struct sk_buff *out_skb; + + /* Skip this skb if it must be acked but the remote has no room for it. */ + if (!cpc_header_number_in_window(send_una, send_wnd, CPC_SKB_CB(skb)->seq)) + break; + + /* Clone and send out the skb */ + out_skb = skb_clone(skb, GFP_KERNEL); + if (!out_skb) + return; + skb_unlink(skb, &cport->holding_queue);

- __cpc_protocol_write_skb(cport, skb, ack); + __cpc_protocol_write_skb(cport, out_skb, ack, CPC_HEADER_MAX_RX_WINDOW); + + cport->tcb.send_nxt++; + skb_queue_tail(&cport->retx_queue, skb); } }

This lets the CPC host device drivers dequeue frames when it's convenient for them to do so, instead of forcing each to them to implement a queue to store pending skbs.

The callback is changed from `transmit` to `wake_tx` and let CPC core notify these drivers when there is something to transmit.

Signed-off-by: Damien Riégel damien.riegel@silabs.com --- drivers/greybus/cpc/host.c | 74 ++++++++++++++++++++++++++++++++++++-- drivers/greybus/cpc/host.h | 12 +++++-- 2 files changed, 81 insertions(+), 5 deletions(-)

diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c index 9a0f8158504..d5ceb657fa9 100644 --- a/drivers/greybus/cpc/host.c +++ b/drivers/greybus/cpc/host.c @@ -161,6 +161,7 @@ static struct gb_hd_driver cpc_gb_driver = { static void cpc_hd_init(struct cpc_host_device *cpc_hd) { mutex_init(&cpc_hd->lock); + skb_queue_head_init(&cpc_hd->tx_queue); }

struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct device *parent) @@ -168,7 +169,7 @@ struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct devic struct cpc_host_device *cpc_hd; struct gb_host_device *hd;

- if (!driver->transmit) { + if (!driver->wake_tx) { dev_err(parent, "missing mandatory callback\n"); return ERR_PTR(-EINVAL); } @@ -237,13 +238,80 @@ EXPORT_SYMBOL_GPL(cpc_hd_rcvd); * @cpc_hd: Host device to send SKB over. * @skb: SKB to send. */ -int cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb) +void cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb) { const struct cpc_hd_driver *drv = cpc_hd->driver;

- return drv->transmit(cpc_hd, skb); + mutex_lock(&cpc_hd->lock); + skb_queue_tail(&cpc_hd->tx_queue, skb); + mutex_unlock(&cpc_hd->lock); + + drv->wake_tx(cpc_hd); }

+/** + * cpc_hd_tx_queue_empty() - Check if transmit queue is empty. + * @cpc_hd: CPC Host Device. + * + * Return: True if transmit queue is empty, false otherwise. + */ +bool cpc_hd_tx_queue_empty(struct cpc_host_device *cpc_hd) +{ + bool empty; + + mutex_lock(&cpc_hd->lock); + empty = skb_queue_empty(&cpc_hd->tx_queue); + mutex_unlock(&cpc_hd->lock); + + return empty; +} +EXPORT_SYMBOL_GPL(cpc_hd_tx_queue_empty); + +/** + * cpc_hd_dequeue() - Get the next SKB that was queued for transmission. + * @cpc_hd: CPC Host Device. + * + * Get an SKB that was previously queued by cpc_hd_send_skb(). + * + * Return: An SKB, or %NULL if queue was empty. + */ +struct sk_buff *cpc_hd_dequeue(struct cpc_host_device *cpc_hd) +{ + struct sk_buff *skb; + + mutex_lock(&cpc_hd->lock); + skb = skb_dequeue(&cpc_hd->tx_queue); + mutex_unlock(&cpc_hd->lock); + + return skb; +} +EXPORT_SYMBOL_GPL(cpc_hd_dequeue); + +/** + * cpc_hd_dequeue_many() - Get the next max_frames SKBs that were queued for transmission. + * @cpc_hd: CPC host device. + * @frame_list: Caller-provided sk_buff_head to fill with dequeued frames. + * @max_frames: Maximum number of frames to dequeue. + * + * Return: Number of frames actually dequeued. + */ +u32 cpc_hd_dequeue_many(struct cpc_host_device *cpc_hd, struct sk_buff_head *frame_list, + unsigned int max_frames) +{ + struct sk_buff *skb; + unsigned int count = 0; + + mutex_lock(&cpc_hd->lock); + while (count < max_frames && (skb = skb_dequeue(&cpc_hd->tx_queue))) { + skb_queue_tail(frame_list, skb); + count++; + } + mutex_unlock(&cpc_hd->lock); + + return count; +} +EXPORT_SYMBOL_GPL(cpc_hd_dequeue_many); + MODULE_DESCRIPTION("Greybus over CPC"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Silicon Laboratories, Inc."); diff --git a/drivers/greybus/cpc/host.h b/drivers/greybus/cpc/host.h index 8f05877b2be..ee6a86de309 100644 --- a/drivers/greybus/cpc/host.h +++ b/drivers/greybus/cpc/host.h @@ -9,6 +9,7 @@ #include <linux/device.h> #include <linux/greybus.h> #include <linux/mutex.h> +#include <linux/skbuff.h> #include <linux/types.h>

#define GB_CPC_MSG_SIZE_MAX 4096 @@ -18,7 +19,7 @@ struct cpc_cport; struct cpc_host_device;

struct cpc_hd_driver { - int (*transmit)(struct cpc_host_device *hd, struct sk_buff *skb); + int (*wake_tx)(struct cpc_host_device *cpc_hd); };

/** @@ -34,6 +35,8 @@ struct cpc_host_device {

struct mutex lock; /* Synchronize access to cports */ struct cpc_cport *cports[GB_CPC_NUM_CPORTS]; + + struct sk_buff_head tx_queue; };

static inline struct device *cpc_hd_dev(struct cpc_host_device *cpc_hd) @@ -47,6 +50,11 @@ void cpc_hd_put(struct cpc_host_device *cpc_hd); void cpc_hd_del(struct cpc_host_device *cpc_hd); void cpc_hd_rcvd(struct cpc_host_device *cpc_hd, struct sk_buff *skb);

-int cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb); +void cpc_hd_send_skb(struct cpc_host_device *cpc_hd, struct sk_buff *skb); + +bool cpc_hd_tx_queue_empty(struct cpc_host_device *cpc_hd); +struct sk_buff *cpc_hd_dequeue(struct cpc_host_device *cpc_hd); +u32 cpc_hd_dequeue_many(struct cpc_host_device *cpc_hd, struct sk_buff_head *frame_list, + unsigned int max_frames);

#endif

From: Gabriel Beaulieu gabriel.beaulieu@silabs.com

This introduces a new module gb-cpc-sdio, in order to communicate with a Greybus CPC device over SDIO.

Most of the complexity stems from aggregation: packets are aggregated to minimize the number of CMD53s. In the first block, the first le32 is the number of packets in this transfer. Immediately after that are all the packet headers (CPC + Greybus). This lets the device process all the headers in a single interrupt, and prepare the ADMA descriptors for all the payloads in one go.

Payloads start at the beginning of the second block and are concatained. Their lengths must be 32-bit aligned, so the driver takes care of adding and removing padding if necessary.

Signed-off-by: Gabriel Beaulieu gabriel.beaulieu@silabs.com Signed-off-by: Damien Riégel damien.riegel@silabs.com --- Changes in v3: - rework defines to group together address-related defines and remove orphaned value - remove trivial comments - all RX and TX are now done from the workqueue. In previous iterations, transfers could either be done from the threaded IRQ or from the workqueue. - remove erroneous SDIO VID/PID - remove padding between headers and payloads when aggregating

Changes in v2: - change formatting from %lu to %zu when printing size_t's - remove "/**" kernel-doc marker for static functions not actually using the kernel-doc format - reduce header inclusion list - use reverse christmas tree variable declarations consistently - update aggregation functions to try to be more legible - use define instead of constant value 0x0C for the address where to read the number of bytes the device wants to send

drivers/greybus/cpc/Kconfig | 12 + drivers/greybus/cpc/Makefile | 3 + drivers/greybus/cpc/sdio.c | 480 +++++++++++++++++++++++++++++++++++ 3 files changed, 495 insertions(+) create mode 100644 drivers/greybus/cpc/sdio.c

diff --git a/drivers/greybus/cpc/Kconfig b/drivers/greybus/cpc/Kconfig index 0e72383381a..50f4c27666d 100644 --- a/drivers/greybus/cpc/Kconfig +++ b/drivers/greybus/cpc/Kconfig @@ -10,3 +10,15 @@ config GREYBUS_CPC

To compile this code as a module, chose M here: the module will be called gb-cpc.ko + +config GREYBUS_CPC_SDIO + tristate "Greybus CPC over SDIO" + depends on GREYBUS_CPC && MMC + help + This driver provides Greybus CPC host support for devices + connected via SDIO interface. + + To compile this driver as a module, choose M here: the module + will be called gb-cpc-sdio. + + If unsure, say N. diff --git a/drivers/greybus/cpc/Makefile b/drivers/greybus/cpc/Makefile index c4b530d27a3..3296536e86d 100644 --- a/drivers/greybus/cpc/Makefile +++ b/drivers/greybus/cpc/Makefile @@ -4,3 +4,6 @@ gb-cpc-y := cport.o header.o host.o protocol.o

# CPC core obj-$(CONFIG_GREYBUS_CPC) += gb-cpc.o + +gb-cpc-sdio-y := sdio.o +obj-$(CONFIG_GREYBUS_CPC_SDIO) += gb-cpc-sdio.o diff --git a/drivers/greybus/cpc/sdio.c b/drivers/greybus/cpc/sdio.c new file mode 100644 index 00000000000..34dfa7c1db1 --- /dev/null +++ b/drivers/greybus/cpc/sdio.c @@ -0,0 +1,480 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2025, Silicon Laboratories, Inc. + */ + +#include <linux/kthread.h> +#include <linux/mmc/sdio_func.h> +#include <linux/mmc/sdio_ids.h> +#include <linux/skbuff.h> +#include <linux/workqueue.h> + +#include "cpc.h" +#include "header.h" +#include "host.h" + +#define GB_CPC_SDIO_MSG_SIZE_MAX 4096 +#define GB_CPC_SDIO_BLOCK_SIZE 256 +#define GB_CPC_SDIO_ALIGNMENT 4 +#define CPC_FRAME_HEADER_SIZE (sizeof(struct cpc_header) + sizeof(struct gb_operation_msg_hdr)) + +#define GB_CPC_SDIO_ADDR_FIFO 0x00 +#define GB_CPC_SDIO_ADDR_RX_BYTES_CNT 0x0C + +enum cpc_sdio_flags { + CPC_SDIO_FLAG_RX_PENDING, + CPC_SDIO_FLAG_SHUTDOWN, +}; + +struct cpc_sdio { + struct cpc_host_device *cpc_hd; + struct device *dev; + struct sdio_func *func; + + struct work_struct rxtx_work; + unsigned long flags; + + wait_queue_head_t event_queue; + u8 max_aggregation; +}; + +struct frame_header { + struct cpc_header cpc; + struct gb_operation_msg_hdr gb; +} __packed; + +static inline struct cpc_sdio *cpc_hd_to_cpc_sdio(struct cpc_host_device *cpc_hd) +{ + return (struct cpc_sdio *)cpc_hd->priv; +} + +static int gb_cpc_sdio_wake_tx(struct cpc_host_device *cpc_hd) +{ + struct cpc_sdio *ctx = cpc_hd_to_cpc_sdio(cpc_hd); + + if (test_bit(CPC_SDIO_FLAG_SHUTDOWN, &ctx->flags)) + return 0; + + schedule_work(&ctx->rxtx_work); + + return 0; +} + +/* + * Return the memory requirement in bytes for the aggregated frame aligned to the block size. + * All headers are contained in a dedicated block. Then payloads start at the beginning of second + * block. Each individual payload must be 4-byte aligned, and the total must be block-aligned. + */ +static size_t cpc_sdio_get_aligned_size(struct cpc_sdio *ctx, struct sk_buff_head *frame_list) +{ + struct sk_buff *frame; + size_t size = 0; + + skb_queue_walk(frame_list, frame) + size += ALIGN(frame->len, GB_CPC_SDIO_ALIGNMENT); + + size = ALIGN(size, GB_CPC_SDIO_BLOCK_SIZE); + + return size; +} + +static size_t cpc_sdio_build_aggregated_frame(struct cpc_sdio *ctx, + struct sk_buff_head *frame_list, + unsigned char **buffer) +{ + unsigned char *tx_buff; + struct sk_buff *frame; + __le32 *frame_count; + size_t xfer_size; + unsigned int i = 0; + + xfer_size = cpc_sdio_get_aligned_size(ctx, frame_list); + + tx_buff = kmalloc(xfer_size, GFP_KERNEL); + if (!tx_buff) + return 0; + + frame_count = (__le32 *)tx_buff; + *frame_count = cpu_to_le32(skb_queue_len(frame_list)); + i += sizeof(*frame_count); + + /* First step is to aggregate all headers together */ + skb_queue_walk(frame_list, frame) { + struct frame_header *fh = (struct frame_header *)&tx_buff[i]; + + memcpy(fh, frame->data, sizeof(*fh)); + i += sizeof(*fh); + } + + skb_queue_walk(frame_list, frame) { + size_t payload_len, padding_len; + + if (frame->len <= CPC_FRAME_HEADER_SIZE) + continue; + + payload_len = frame->len - CPC_FRAME_HEADER_SIZE; + memcpy(&tx_buff[i], &frame->data[CPC_FRAME_HEADER_SIZE], payload_len); + i += payload_len; + + padding_len = ALIGN(payload_len, GB_CPC_SDIO_ALIGNMENT) - payload_len; + if (padding_len) { + memset(&tx_buff[i], 0, padding_len); + i += padding_len; + } + } + + *buffer = tx_buff; + + return xfer_size; +} + +static bool cpc_sdio_get_payload_size(struct cpc_sdio *ctx, const struct frame_header *header, + size_t *payload_size) +{ + size_t gb_size; + + gb_size = le16_to_cpu(header->gb.size); + + if (gb_size < sizeof(header->gb)) { + dev_dbg(ctx->dev, "Invalid Greybus header size: %zu\n", gb_size); + return false; + } + + if (gb_size > (GB_CPC_SDIO_MSG_SIZE_MAX + sizeof(header->gb))) { + dev_dbg(ctx->dev, "Payload size exceeds maximum: %zu\n", gb_size); + return false; + } + + *payload_size = gb_size - sizeof(header->gb); + + return true; +} + +/* + * Process aggregated frame + * Reconstructed frame layout: + * +-----+-----+-----+------+------+------+------+-------+---------+ + * | CPC Header (4B) | Size | OpID | Type | Stat | CPort | Payload | + * +-----+-----+-----+------+------+------+------+-------+---------+ + */ +static void cpc_sdio_process_aggregated_frame(struct cpc_sdio *ctx, unsigned char *aggregated_frame, + unsigned int frame_len) +{ + const unsigned char *payload_start; + const struct frame_header *header; + unsigned int payload_offset; + size_t aligned_payload_size; + struct sk_buff *rx_skb; + __le32 frame_count_le; + size_t payload_size; + size_t frame_size; + u32 frame_count; + + frame_count_le = *((__le32 *)aggregated_frame); + frame_count = le32_to_cpu(frame_count_le); + + if (frame_count > ctx->max_aggregation) { + dev_warn(ctx->dev, + "Process aggregated frame: frame count %u exceeds negotiated maximum %u\n", + frame_count, ctx->max_aggregation); + return; + } + + /* Header starts at block 0 after frame count */ + header = (struct frame_header *)&aggregated_frame[sizeof(frame_count_le)]; + + /* Payloads start at block 1 (after complete block 0) */ + payload_offset = (frame_count * CPC_FRAME_HEADER_SIZE) + sizeof(frame_count_le); + + for (unsigned int i = 0; i < frame_count; i++) { + payload_start = &aggregated_frame[payload_offset]; + + if (!cpc_sdio_get_payload_size(ctx, header, &payload_size)) { + dev_err(ctx->dev, + "Process aggregated frame: failed to get payload size, aborting.\n"); + return; + } + + aligned_payload_size = ALIGN(payload_size, GB_CPC_SDIO_ALIGNMENT); + + if (payload_offset + aligned_payload_size > frame_len) { + dev_err(ctx->dev, + "Process aggregated frame: payload is out of buffer boundary, aborting at frame %u\n", + i); + return; + } + + frame_size = CPC_FRAME_HEADER_SIZE + payload_size; + + rx_skb = alloc_skb(frame_size, GFP_KERNEL); + if (!rx_skb) + return; + + memcpy(skb_put(rx_skb, CPC_FRAME_HEADER_SIZE), header, CPC_FRAME_HEADER_SIZE); + + if (payload_size > 0) + memcpy(skb_put(rx_skb, payload_size), payload_start, payload_size); + + cpc_hd_rcvd(ctx->cpc_hd, rx_skb); + + header++; + payload_offset += aligned_payload_size; + } +} + +static u32 cpc_sdio_get_rx_num_bytes(struct sdio_func *func, int *err) +{ + unsigned int rx_num_block_addr = GB_CPC_SDIO_ADDR_RX_BYTES_CNT; + + return sdio_readl(func, rx_num_block_addr, err); +} + +static void gb_cpc_sdio_rx(struct cpc_sdio *ctx) +{ + unsigned char *rx_buff; + size_t data_len; + int err; + + sdio_claim_host(ctx->func); + data_len = cpc_sdio_get_rx_num_bytes(ctx->func, &err); + + if (err) { + dev_err(ctx->dev, "failed to obtain byte count (%d)\n", err); + goto release_host; + } + + if (data_len < sizeof(u32) + CPC_FRAME_HEADER_SIZE) { + dev_err(ctx->dev, "failed to obtain enough bytes for a header (%zu)\n", data_len); + goto release_host; + } + + rx_buff = kmalloc(data_len, GFP_KERNEL); + if (!rx_buff) + goto release_host; + + err = sdio_readsb(ctx->func, rx_buff, GB_CPC_SDIO_ADDR_FIFO, data_len); + sdio_release_host(ctx->func); + + if (err) { + dev_err(ctx->dev, "failed to sdio_readsb (%d)\n", err); + goto free_rx_skb; + } + + if (data_len < GB_CPC_SDIO_BLOCK_SIZE) { + dev_err(ctx->dev, "received %zd bytes, expected at least %u bytes\n", data_len, + GB_CPC_SDIO_BLOCK_SIZE); + goto free_rx_skb; + } + + cpc_sdio_process_aggregated_frame(ctx, rx_buff, data_len); + +free_rx_skb: + kfree(rx_buff); + + return; + +release_host: + sdio_release_host(ctx->func); +} + +static int gb_cpc_sdio_tx(struct cpc_sdio *ctx) +{ + struct sk_buff_head frame_list; + unsigned char *tx_buff; + size_t tx_len; + int pkt_sent; + int err; + + skb_queue_head_init(&frame_list); + + cpc_hd_dequeue_many(ctx->cpc_hd, &frame_list, ctx->max_aggregation); + + if (skb_queue_empty(&frame_list)) + return 0; + + tx_len = cpc_sdio_build_aggregated_frame(ctx, &frame_list, &tx_buff); + if (!tx_len) { + dev_err(ctx->dev, "failed to build aggregated frame\n"); + goto cleanup_frames; + } + + sdio_claim_host(ctx->func); + err = sdio_writesb(ctx->func, GB_CPC_SDIO_ADDR_FIFO, tx_buff, tx_len); + sdio_release_host(ctx->func); + + kfree(tx_buff); + +cleanup_frames: + pkt_sent = skb_queue_len(&frame_list); + skb_queue_purge(&frame_list); + + return pkt_sent; +} + +static void gb_cpc_sdio_rxtx_work(struct work_struct *work) +{ + struct cpc_sdio *ctx = container_of(work, struct cpc_sdio, rxtx_work); + int num_tx = 0; + + do { + if (test_and_clear_bit(CPC_SDIO_FLAG_RX_PENDING, &ctx->flags)) + gb_cpc_sdio_rx(ctx); + + num_tx = gb_cpc_sdio_tx(ctx); + } while (num_tx); +} + +static struct cpc_hd_driver cpc_sdio_driver = { + .wake_tx = gb_cpc_sdio_wake_tx, +}; + +static int cpc_sdio_init(struct sdio_func *func) +{ + unsigned char rx_data_ready_irq_en_bit = BIT(0); + unsigned int irq_enable_addr = 0x09; + int err; + + sdio_writeb(func, rx_data_ready_irq_en_bit, irq_enable_addr, &err); + + return err; +} + +static void cpc_sdio_irq_handler(struct sdio_func *func) +{ + unsigned int rx_data_pending_irq_bit = 0; + unsigned int irq_status_addr = 0x08; + unsigned long int_status; + struct cpc_sdio *ctx; + struct device *dev; + int err; + + ctx = sdio_get_drvdata(func); + dev = &func->dev; + + int_status = sdio_readb(func, irq_status_addr, &err); + if (err) + return; + + if (__test_and_clear_bit(rx_data_pending_irq_bit, &int_status)) { + sdio_writeb(func, BIT(rx_data_pending_irq_bit), irq_status_addr, &err); + if (err) + return; + + set_bit(CPC_SDIO_FLAG_RX_PENDING, &ctx->flags); + schedule_work(&ctx->rxtx_work); + } + + if (int_status) + dev_err_once(dev, "unhandled interrupt from the device (%ld)\n", int_status); +} + +static int cpc_sdio_probe(struct sdio_func *func, const struct sdio_device_id *id) +{ + struct cpc_host_device *cpc_hd; + struct cpc_sdio *ctx; + int err; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + cpc_hd = cpc_hd_create(&cpc_sdio_driver, &func->dev, ctx); + if (IS_ERR(cpc_hd)) { + kfree(ctx); + return PTR_ERR(cpc_hd); + } + + ctx->cpc_hd = cpc_hd; + ctx->dev = cpc_hd_dev(cpc_hd); + ctx->func = func; + ctx->max_aggregation = 1; + + INIT_WORK(&ctx->rxtx_work, gb_cpc_sdio_rxtx_work); + + sdio_set_drvdata(func, ctx); + + sdio_claim_host(func); + + err = sdio_enable_func(func); + if (err) + goto release_host; + + err = sdio_set_block_size(func, GB_CPC_SDIO_BLOCK_SIZE); + if (err) + goto disable_func; + + err = cpc_sdio_init(func); + if (err) + goto disable_func; + + err = sdio_claim_irq(func, cpc_sdio_irq_handler); + if (err) + goto disable_func; + + err = cpc_hd_add(cpc_hd); + if (err) + goto release_irq; + + sdio_release_host(func); + + return 0; + +release_irq: + sdio_release_irq(func); + +disable_func: + sdio_disable_func(func); + +release_host: + sdio_release_host(func); + cpc_hd_put(cpc_hd); + kfree(ctx); + + return err; +} + +static void cpc_sdio_remove(struct sdio_func *func) +{ + struct cpc_sdio *ctx = sdio_get_drvdata(func); + struct cpc_host_device *cpc_hd = ctx->cpc_hd; + + set_bit(CPC_SDIO_FLAG_SHUTDOWN, &ctx->flags); + + + sdio_claim_host(func); + sdio_release_irq(func); + + cancel_work_sync(&ctx->rxtx_work); + + sdio_disable_func(func); + sdio_release_host(func); + + cpc_hd_del(cpc_hd); + cpc_hd_put(cpc_hd); + + kfree(ctx); +} + +static const struct sdio_device_id sdio_ids[] = { + /* No official ID */ + { SDIO_DEVICE(0x0000, 0x1000), }, + { }, +}; +MODULE_DEVICE_TABLE(sdio, sdio_ids); + +static struct sdio_driver gb_cpc_sdio_driver = { + .name = KBUILD_MODNAME, + .id_table = sdio_ids, + .probe = cpc_sdio_probe, + .remove = cpc_sdio_remove, + .drv = { + .owner = THIS_MODULE, + .name = KBUILD_MODNAME, + }, +}; + +module_sdio_driver(gb_cpc_sdio_driver); + +MODULE_DESCRIPTION("Greybus Host Driver for Silicon Labs devices using SDIO"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Damien Riégel damien.riegel@silabs.com");