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Subject[PATCHv8] drivers: optee: allow op-tee to access devices on the i2c bus
Date
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>
---

v8: review fixes
fix types and add TEEC_ERROR_NOT_SUPPORTED to GP errors
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/optee_private.h | 1 +
drivers/tee/optee/rpc.c | 96 +++++++++++++++++++++++++++++++
3 files changed, 118 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/optee_private.h b/drivers/tee/optee/optee_private.h
index 8b71839a357e..564116d6cc58 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -17,6 +17,7 @@
/* Some Global Platform error codes used in this driver */
#define TEEC_SUCCESS 0x00000000
#define TEEC_ERROR_BAD_PARAMETERS 0xFFFF0006
+#define TEEC_ERROR_NOT_SUPPORTED 0xFFFF000A
#define TEEC_ERROR_COMMUNICATION 0xFFFF000E
#define TEEC_ERROR_OUT_OF_MEMORY 0xFFFF000C
#define TEEC_ERROR_SHORT_BUFFER 0xFFFF0010
diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c
index b4ade54d1f28..cc9ad4b68d40 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 +50,98 @@ 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;
+ size_t i;
+ int ret = -EOPNOTSUPP;
+ u8 attr[] = {
+ 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++) {
+ 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 {
+ if (optee_to_msg_param(arg->params, arg->num_params, params)) {
+ arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+ } else {
+ params[3].u.value.a = ret;
+ arg->ret = TEEC_SUCCESS;
+ }
+ }
+
+ 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_NOT_SUPPORTED;
+}
+#endif
+
static struct wq_entry *wq_entry_get(struct optee_wait_queue *wq, u32 key)
{
struct wq_entry *w;
@@ -382,6 +475,9 @@ 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
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