This commit gives the secure world access to the I2C bus so it can
communicate with I2C slaves (typically those would be secure elements
like the NXP SE050).

A similar service implementation has been merged in linux:
c05210ab ("drivers: optee: allow op-tee to access devices on the i2c
bus")

Signed-off-by: Jorge Ramirez-Ortiz <jo...@foundries.io>
Reviewed-by: Simon Glass <s...@chromium.org>
---
 drivers/tee/optee/Makefile               |  1 +
 drivers/tee/optee/i2c.c                  | 90 ++++++++++++++++++++++++
 drivers/tee/optee/optee_msg.h            | 21 ++++++
 drivers/tee/optee/optee_msg_supplicant.h |  5 ++
 drivers/tee/optee/optee_private.h        | 17 +++++
 drivers/tee/optee/supplicant.c           |  3 +
 6 files changed, 137 insertions(+)
 create mode 100644 drivers/tee/optee/i2c.c

diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
index 928d3f8002..068c6e7aa1 100644
--- a/drivers/tee/optee/Makefile
+++ b/drivers/tee/optee/Makefile
@@ -2,4 +2,5 @@
 
 obj-y += core.o
 obj-y += supplicant.o
+obj-$(CONFIG_DM_I2C) += i2c.o
 obj-$(CONFIG_SUPPORT_EMMC_RPMB) += rpmb.o
diff --git a/drivers/tee/optee/i2c.c b/drivers/tee/optee/i2c.c
new file mode 100644
index 0000000000..ef4e10f991
--- /dev/null
+++ b/drivers/tee/optee/i2c.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * Copyright (c) 2020 Foundries.io Ltd
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <i2c.h>
+#include <tee.h>
+#include "optee_msg.h"
+#include "optee_private.h"
+
+static int check_xfer_flags(struct udevice *chip, uint tee_flags)
+{
+       uint flags;
+       int ret;
+
+       ret = i2c_get_chip_flags(chip, &flags);
+       if (ret)
+               return ret;
+
+       if (tee_flags & OPTEE_MSG_RPC_CMD_I2C_FLAGS_TEN_BIT) {
+               if (!(flags & DM_I2C_CHIP_10BIT))
+                       return -EINVAL;
+       } else {
+               if (flags & DM_I2C_CHIP_10BIT)
+                       return -EINVAL;
+       }
+
+       return 0;
+}
+
+void optee_suppl_cmd_i2c_transfer(struct optee_msg_arg *arg)
+{
+       const u8 attr[] = {
+               OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,
+               OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,
+               OPTEE_MSG_ATTR_TYPE_RMEM_INOUT,
+               OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT,
+       };
+       struct udevice *chip_dev;
+       struct tee_shm *shm;
+       u8 *buf;
+       int ret;
+
+       if (arg->num_params != ARRAY_SIZE(attr) ||
+           arg->params[0].attr != attr[0] ||
+           arg->params[1].attr != attr[1] ||
+           arg->params[2].attr != attr[2] ||
+           arg->params[3].attr != attr[3]) {
+               goto bad;
+       }
+
+       shm = (struct tee_shm *)(unsigned long)arg->params[2].u.rmem.shm_ref;
+       buf = shm->addr;
+       if (!buf)
+               goto bad;
+
+       if (i2c_get_chip_for_busnum((int)arg->params[0].u.value.b,
+                                   (int)arg->params[0].u.value.c,
+                                   0, &chip_dev))
+               goto bad;
+
+       if (check_xfer_flags(chip_dev, arg->params[1].u.value.a))
+               goto bad;
+
+       switch (arg->params[0].u.value.a) {
+       case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:
+               ret = dm_i2c_read(chip_dev, 0, buf,
+                                 (size_t)arg->params[2].u.rmem.size);
+               break;
+       case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:
+               ret = dm_i2c_write(chip_dev, 0, buf,
+                                  (size_t)arg->params[2].u.rmem.size);
+               break;
+       default:
+               goto bad;
+       }
+
+       if (ret) {
+               arg->ret = TEE_ERROR_COMMUNICATION;
+       } else {
+               arg->params[3].u.value.a = arg->params[2].u.rmem.size;
+               arg->ret = TEE_SUCCESS;
+       }
+
+       return;
+bad:
+       arg->ret = TEE_ERROR_BAD_PARAMETERS;
+}
diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
index 24c60960fc..8d40ce60c2 100644
--- a/drivers/tee/optee/optee_msg.h
+++ b/drivers/tee/optee/optee_msg.h
@@ -422,4 +422,25 @@ 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_msg_supplicant.h 
b/drivers/tee/optee/optee_msg_supplicant.h
index a0fb8063c8..963cfd4782 100644
--- a/drivers/tee/optee/optee_msg_supplicant.h
+++ b/drivers/tee/optee/optee_msg_supplicant.h
@@ -147,6 +147,11 @@
 #define OPTEE_MSG_RPC_CMD_SHM_ALLOC    6
 #define OPTEE_MSG_RPC_CMD_SHM_FREE     7
 
+/*
+ * I2C bus access
+ */
+#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 21
+
 /*
  * Was OPTEE_MSG_RPC_CMD_SQL_FS, which isn't supported any longer
  */
diff --git a/drivers/tee/optee/optee_private.h 
b/drivers/tee/optee/optee_private.h
index 9442d1c176..1f07a27ee4 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -60,6 +60,23 @@ static inline void optee_suppl_rpmb_release(struct udevice 
*dev)
 }
 #endif
 
+#ifdef CONFIG_DM_I2C
+/**
+ * optee_suppl_cmd_i2c_transfer() - route I2C requests to an I2C chip
+ * @arg:       OP-TEE message (layout specified in optee_msg.h) defining the
+ *             transfer mode (read/write), adapter, chip and control flags.
+ *
+ * Handles OP-TEE requests to transfer data to the I2C chip on the I2C adapter.
+ */
+void optee_suppl_cmd_i2c_transfer(struct optee_msg_arg *arg);
+#else
+static inline void optee_suppl_cmd_i2c_transfer(struct optee_msg_arg *arg)
+{
+       debug("OPTEE_MSG_RPC_CMD_I2C_TRANSFER not implemented\n");
+       arg->ret = TEE_ERROR_NOT_IMPLEMENTED;
+}
+#endif
+
 void *optee_alloc_and_init_page_list(void *buf, ulong len, u64 *phys_buf_ptr);
 
 #endif /* __OPTEE_PRIVATE_H */
diff --git a/drivers/tee/optee/supplicant.c b/drivers/tee/optee/supplicant.c
index ae042b9a20..f9dd874b59 100644
--- a/drivers/tee/optee/supplicant.c
+++ b/drivers/tee/optee/supplicant.c
@@ -89,6 +89,9 @@ void optee_suppl_cmd(struct udevice *dev, struct tee_shm 
*shm_arg,
        case OPTEE_MSG_RPC_CMD_RPMB:
                optee_suppl_cmd_rpmb(dev, arg);
                break;
+       case OPTEE_MSG_RPC_CMD_I2C_TRANSFER:
+               optee_suppl_cmd_i2c_transfer(arg);
+               break;
        default:
                arg->ret = TEE_ERROR_NOT_IMPLEMENTED;
        }
-- 
2.17.1

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