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Subject[PATCH v2] 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>
---
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
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