Re: [PATCH v2] drivers: optee: allow op-tee to access devices on the i2c bus

From: Jorge Ramirez-Ortiz, Foundries
Date: Sun Jun 07 2020 - 13:38:38 EST


On 01/06/20, 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.


any comments please?


>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge@xxxxxxxxxxxx>
> ---
> drivers/tee/optee/optee_msg.h | 18 +++++++++++
> drivers/tee/optee/rpc.c | 57 +++++++++++++++++++++++++++++++++++
> 2 files changed, 75 insertions(+)
>
> diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
> index 795bc19ae17a..b6cc964fdeea 100644
> --- a/drivers/tee/optee/optee_msg.h
> +++ b/drivers/tee/optee/optee_msg.h
> @@ -419,4 +419,22 @@ 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
> + *
> + * [io] param[1].u.tmem.buf_ptr physical address
> + * [io] param[1].u.tmem.size transfer size in bytes
> + * [io] param[1].u.tmem.shm_ref shared memory reference
> + *
> + * [out] param[0].u.value.a bytes transferred
> + *
> + */
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 8
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD 0
> +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR 1
> +
> #endif /* _OPTEE_MSG_H */
> diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c
> index b4ade54d1f28..21d452805c6f 100644
> --- a/drivers/tee/optee/rpc.c
> +++ b/drivers/tee/optee/rpc.c
> @@ -9,6 +9,7 @@
> #include <linux/device.h>
> #include <linux/slab.h>
> #include <linux/tee_drv.h>
> +#include <linux/i2c.h>
> #include "optee_private.h"
> #include "optee_smc.h"
>
> @@ -48,6 +49,59 @@ static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg)
> bad:
> arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> }
> +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> + struct optee_msg_arg *arg)
> +{
> + struct i2c_client client;
> + struct tee_shm *shm;
> + int i, ret;
> + char *buf;
> + uint32_t attr[] = {
> + OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,
> + OPTEE_MSG_ATTR_TYPE_TMEM_INOUT,
> + OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT,
> + };
> +
> + if (arg->num_params != ARRAY_SIZE(attr))
> + goto bad;
> +
> + for (i = 0; i < ARRAY_SIZE(attr); i++)
> + if ((arg->params[i].attr & OPTEE_MSG_ATTR_TYPE_MASK) != attr[i])
> + goto bad;
> +
> + shm = (struct tee_shm *)(unsigned long)arg->params[1].u.tmem.shm_ref;
> + buf = (char *)shm->kaddr;
> +
> + client.addr = arg->params[0].u.value.c;
> + client.adapter = i2c_get_adapter(arg->params[0].u.value.b);
> + if (!client.adapter)
> + goto bad;
> +
> + snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);
> +
> + switch (arg->params[0].u.value.a) {
> + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:
> + ret = i2c_master_recv(&client, buf, arg->params[1].u.tmem.size);
> + break;
> + case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:
> + ret = i2c_master_send(&client, buf, arg->params[1].u.tmem.size);
> + break;
> + default:
> + i2c_put_adapter(client.adapter);
> + goto bad;
> + }
> +
> + if (ret >= 0) {
> + arg->params[2].u.value.a = ret;
> + arg->ret = TEEC_SUCCESS;
> + } else
> + arg->ret = TEEC_ERROR_COMMUNICATION;
> +
> + i2c_put_adapter(client.adapter);
> + return;
> +bad:
> + arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> +}
>
> static struct wq_entry *wq_entry_get(struct optee_wait_queue *wq, u32 key)
> {
> @@ -382,6 +436,9 @@ 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
>