Re: [Tee-dev] [PATCHv7] drivers: optee: allow op-tee to access devices on the i2c bus

On Tue, Aug 11, 2020 at 07:55:31PM +0200, Jorge Ramirez-Ortiz wrote:

Some secure elements like NXP's SE050 sit on I2C buses. For OP-TEE to control this type of cryptographic devices it needs coordinated access to the bus, so collisions and RUNTIME_PM dont get in the way.

This trampoline driver allow OP-TEE to access them.

Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io

v7: add support for ten bit i2c slave addressing v6: compile out if CONFIG_I2C not enabled v5: alphabetic order of includes v4: remove unnecessary extra line in optee_msg.h v3: use from/to msg param to support all types of memory modify OPTEE_MSG_RPC_CMD_I2C_TRANSFER message id drivers/tee/optee/optee_msg.h | 21 ++++++++ drivers/tee/optee/rpc.c | 95 +++++++++++++++++++++++++++++++++++ 2 files changed, 116 insertions(+)

diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 795bc19ae17a..7b2d919da2ac 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -419,4 +419,25 @@ struct optee_msg_arg { */ #define OPTEE_MSG_RPC_CMD_SHM_FREE 7 +/*

• • Access a device on an i2c bus
• • [in] param[0].u.value.a mode: RD(0), WR(1)
• • [in] param[0].u.value.b i2c adapter
• • [in] param[0].u.value.c i2c chip
• • [in] param[1].u.value.a i2c control flags
• • [in/out] memref[2] buffer to exchange the transfer data

• • 			with the secure world
    

• • [out] param[3].u.value.a bytes transferred by the driver
• */

+#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 21 +/* I2C master transfer modes */ +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD 0 +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR 1 +/* I2C master control flags */ +#define OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT BIT(0)

#endif /* _OPTEE_MSG_H */ diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c index b4ade54d1f28..b6178761d79f 100644 --- a/drivers/tee/optee/rpc.c +++ b/drivers/tee/optee/rpc.c @@ -7,6 +7,7 @@ #include <linux/delay.h> #include <linux/device.h> +#include <linux/i2c.h> #include <linux/slab.h> #include <linux/tee_drv.h> #include "optee_private.h" @@ -49,6 +50,97 @@ static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg) arg->ret = TEEC_ERROR_BAD_PARAMETERS; } +#if IS_ENABLED(CONFIG_I2C) +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,

• 			     struct optee_msg_arg *arg)
  

+{

• struct i2c_client client = { 0 };
• struct tee_param *params;
• int i, ret = -EOPNOTSUPP;
• uint32_t attr[] = {

uint32_t seems a randomly chosen type here. The TEE_IOCTL_PARAM_ATTR_TYPE_* defines fit in a u8. Consider u8 attr[] = { instead.

• TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
  

• TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
  

• TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
  

• TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT,
  

• };
• if (arg->num_params != ARRAY_SIZE(attr)) {

• arg->ret = TEEC_ERROR_BAD_PARAMETERS;
  

• return;
  

• }
• params = kmalloc_array(arg->num_params, sizeof(struct tee_param),

• 	       GFP_KERNEL);
  

• if (!params) {

• arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
  

• return;
  

• }
• if (optee_from_msg_param(params, arg->num_params, arg->params))

• goto bad;
  

• for (i = 0; i < arg->num_params; i++) {

arg->num_params has an unsigned type. Consider giving i an unsigned type too.

• if ((params[i].attr & TEE_IOCTL_PARAM_ATTR_TYPE_MASK)
  

•     != attr[i])
  

It looks a bit funny with the comparison at the beginning of the line, normally we try to leave those at the end of the line. But optee_from_msg_param() doesn't set any higher bits in params[i].attr so you could also simplify the expression as: if (params[i].attr != attr[i])

• 	goto bad;
  

• }
• client.adapter = i2c_get_adapter(params[0].u.value.b);
• if (!client.adapter)

• goto bad;
  

• if (params[1].u.value.a & OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT) {

• if (!i2c_check_functionality(client.adapter,
  

• 			     I2C_FUNC_10BIT_ADDR)) {
  

• 	i2c_put_adapter(client.adapter);
  

• 	goto bad;
  

• }
  

• client.flags = I2C_CLIENT_TEN;
  

• }
• client.addr = params[0].u.value.c;
• snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);
• switch (params[0].u.value.a) {
• case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:

• ret = i2c_master_recv(&client, params[2].u.memref.shm->kaddr,
  

• 		      params[2].u.memref.size);
  

• break;
  

• case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:

• ret = i2c_master_send(&client, params[2].u.memref.shm->kaddr,
  

• 		      params[2].u.memref.size);
  

• break;
  

• default:

• i2c_put_adapter(client.adapter);
  

• goto bad;
  

• }
• if (ret < 0) {

• arg->ret = TEEC_ERROR_COMMUNICATION;
  

• } else {

• params[3].u.value.a = ret;
  

• arg->ret = TEEC_SUCCESS;
  

• if (optee_to_msg_param(arg->params, arg->num_params, params))
  

• 	arg->ret = TEEC_ERROR_BAD_PARAMETERS;
  

Need arg->ret = TEEC_SUCCESS; when everything is OK.

• }
• i2c_put_adapter(client.adapter);
• kfree(params);
• return;

+bad:

• kfree(params);
• arg->ret = TEEC_ERROR_BAD_PARAMETERS;

+} +#else +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,

• 			     struct optee_msg_arg *arg)
  

+{

• arg->ret = TEEC_ERROR_COMMUNICATION;

I'd prefer TEEC_ERROR_NOT_SUPPORTED here. TEEC_ERROR_NOT_SUPPORTED would need to be defined as: #define TEEC_ERROR_NOT_SUPPORTED 0xFFFF000A in optee_private.h

Cheers, Jens

+} +#endif

static struct wq_entry *wq_entry_get(struct optee_wait_queue *wq, u32 key) { struct wq_entry *w; @@ -382,6 +474,9 @@ static void handle_rpc_func_cmd(struct tee_context *ctx, struct optee *optee, case OPTEE_MSG_RPC_CMD_SHM_FREE: handle_rpc_func_cmd_shm_free(ctx, arg); break;

• case OPTEE_MSG_RPC_CMD_I2C_TRANSFER:

• handle_rpc_func_cmd_i2c_transfer(ctx, arg);
  

• break;
  

  default: handle_rpc_supp_cmd(ctx, arg); }

-- 2.17.1