[PATCH v8 1/4] drivers: tee: i2c trampoline driver

[Igor Opaniuk <igor.opaniuk@foundries.io>]

From: Jorge Ramirez-Ortiz <jorge@foundries.io>

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 <jorge@foundries.io>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.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;
 	}
-- 
2.25.1