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);