nvmem: stm32: add OP-TEE support for STM32MP13x

For boot with OP-TEE on STM32MP13, the communication with the secure
world no more use STMicroelectronics SMC but communication with the
STM32MP BSEC TA, for data access (read/write) or lock operation:
- all the request are sent to OP-TEE trusted application,
- for upper OTP with ECC protection and with word programming only
  each OTP are permanently locked when programmed to avoid ECC error
  on the second write operation

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230206134356.839737-18-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 298 insertions, 0 deletions

diff --git a/drivers/nvmem/stm32-bsec-optee-ta.c b/drivers/nvmem/stm32-bsec-optee-ta.c
new file mode 100644
index 000000000000..f89ce791dd12
--- /dev/null
+++ b/drivers/nvmem/stm32-bsec-optee-ta.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OP-TEE STM32MP BSEC PTA interface, used by STM32 ROMEM driver
+ *
+ * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
+ */
+
+#include <linux/tee_drv.h>
+
+#include "stm32-bsec-optee-ta.h"
+
+/*
+ * Read OTP memory
+ *
+ * [in]		value[0].a		OTP start offset in byte
+ * [in]		value[0].b		Access type (0:shadow, 1:fuse, 2:lock)
+ * [out]	memref[1].buffer	Output buffer to store read values
+ * [out]	memref[1].size		Size of OTP to be read
+ *
+ * Return codes:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_ACCESS_DENIED - OTP not accessible by caller
+ */
+#define PTA_BSEC_READ_MEM		0x0
+
+/*
+ * Write OTP memory
+ *
+ * [in]		value[0].a		OTP start offset in byte
+ * [in]		value[0].b		Access type (0:shadow, 1:fuse, 2:lock)
+ * [in]		memref[1].buffer	Input buffer to read values
+ * [in]		memref[1].size		Size of OTP to be written
+ *
+ * Return codes:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_ACCESS_DENIED - OTP not accessible by caller
+ */
+#define PTA_BSEC_WRITE_MEM		0x1
+
+/* value of PTA_BSEC access type = value[in] b */
+#define SHADOW_ACCESS	0
+#define FUSE_ACCESS	1
+#define LOCK_ACCESS	2
+
+/* Bitfield definition for LOCK status */
+#define LOCK_PERM			BIT(30)
+
+/* OP-TEE STM32MP BSEC TA UUID */
+static const uuid_t stm32mp_bsec_ta_uuid =
+	UUID_INIT(0x94cf71ad, 0x80e6, 0x40b5,
+		  0xa7, 0xc6, 0x3d, 0xc5, 0x01, 0xeb, 0x28, 0x03);
+
+/*
+ * Check whether this driver supports the BSEC TA in the TEE instance
+ * represented by the params (ver/data) to this function.
+ */
+static int stm32_bsec_optee_ta_match(struct tee_ioctl_version_data *ver,
+				     const void *data)
+{
+	/* Currently this driver only supports GP compliant, OP-TEE based TA */
+	if ((ver->impl_id == TEE_IMPL_ID_OPTEE) &&
+		(ver->gen_caps & TEE_GEN_CAP_GP))
+		return 1;
+	else
+		return 0;
+}
+
+/* Open a session to OP-TEE for STM32MP BSEC TA */
+static int stm32_bsec_ta_open_session(struct tee_context *ctx, u32 *id)
+{
+	struct tee_ioctl_open_session_arg sess_arg;
+	int rc;
+
+	memset(&sess_arg, 0, sizeof(sess_arg));
+	export_uuid(sess_arg.uuid, &stm32mp_bsec_ta_uuid);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
+	sess_arg.num_params = 0;
+
+	rc = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != 0)) {
+		pr_err("%s: tee_client_open_session failed err:%#x, ret:%#x\n",
+		       __func__, sess_arg.ret, rc);
+		if (!rc)
+			rc = -EINVAL;
+	} else {
+		*id = sess_arg.session;
+	}
+
+	return rc;
+}
+
+/* close a session to OP-TEE for STM32MP BSEC TA */
+static void stm32_bsec_ta_close_session(void *ctx, u32 id)
+{
+	tee_client_close_session(ctx, id);
+}
+
+/* stm32_bsec_optee_ta_open() - initialize the STM32MP BSEC TA */
+int stm32_bsec_optee_ta_open(struct tee_context **ctx)
+{
+	struct tee_context *tee_ctx;
+	u32 session_id;
+	int rc;
+
+	/* Open context with TEE driver */
+	tee_ctx = tee_client_open_context(NULL, stm32_bsec_optee_ta_match, NULL, NULL);
+	if (IS_ERR(tee_ctx)) {
+		rc = PTR_ERR(tee_ctx);
+		if (rc == -ENOENT)
+			return -EPROBE_DEFER;
+		pr_err("%s: tee_client_open_context failed (%d)\n", __func__, rc);
+
+		return rc;
+	}
+
+	/* Check STM32MP BSEC TA presence */
+	rc = stm32_bsec_ta_open_session(tee_ctx, &session_id);
+	if (rc) {
+		tee_client_close_context(tee_ctx);
+		return rc;
+	}
+
+	stm32_bsec_ta_close_session(tee_ctx, session_id);
+
+	*ctx = tee_ctx;
+
+	return 0;
+}
+
+/* stm32_bsec_optee_ta_open() - release the PTA STM32MP BSEC TA */
+void stm32_bsec_optee_ta_close(void *ctx)
+{
+	tee_client_close_context(ctx);
+}
+
+/* stm32_bsec_optee_ta_read() - nvmem read access using PTA client driver */
+int stm32_bsec_optee_ta_read(struct tee_context *ctx, unsigned int offset,
+			     void *buf, size_t bytes)
+{
+	struct tee_shm *shm;
+	struct tee_ioctl_invoke_arg arg;
+	struct tee_param param[2];
+	u8 *shm_buf;
+	u32 start, num_bytes;
+	int ret;
+	u32 session_id;
+
+	ret = stm32_bsec_ta_open_session(ctx, &session_id);
+	if (ret)
+		return ret;
+
+	memset(&arg, 0, sizeof(arg));
+	memset(&param, 0, sizeof(param));
+
+	arg.func = PTA_BSEC_READ_MEM;
+	arg.session = session_id;
+	arg.num_params = 2;
+
+	/* align access on 32bits */
+	start = ALIGN_DOWN(offset, 4);
+	num_bytes = round_up(offset + bytes - start, 4);
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
+	param[0].u.value.a = start;
+	param[0].u.value.b = SHADOW_ACCESS;
+
+	shm = tee_shm_alloc_kernel_buf(ctx, num_bytes);
+	if (IS_ERR(shm)) {
+		ret = PTR_ERR(shm);
+		goto out_tee_session;
+	}
+
+	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+	param[1].u.memref.shm = shm;
+	param[1].u.memref.size = num_bytes;
+
+	ret = tee_client_invoke_func(ctx, &arg, param);
+	if (ret < 0 || arg.ret != 0) {
+		pr_err("TA_BSEC invoke failed TEE err:%#x, ret:%#x\n",
+			arg.ret, ret);
+		if (!ret)
+			ret = -EIO;
+	}
+	if (!ret) {
+		shm_buf = tee_shm_get_va(shm, 0);
+		if (IS_ERR(shm_buf)) {
+			ret = PTR_ERR(shm_buf);
+			pr_err("tee_shm_get_va failed for transmit (%d)\n", ret);
+		} else {
+			/* read data from 32 bits aligned buffer */
+			memcpy(buf, &shm_buf[offset % 4], bytes);
+		}
+	}
+
+	tee_shm_free(shm);
+
+out_tee_session:
+	stm32_bsec_ta_close_session(ctx, session_id);
+
+	return ret;
+}
+
+/* stm32_bsec_optee_ta_write() - nvmem write access using PTA client driver */
+int stm32_bsec_optee_ta_write(struct tee_context *ctx, unsigned int lower,
+			      unsigned int offset, void *buf, size_t bytes)
+{	struct tee_shm *shm;
+	struct tee_ioctl_invoke_arg arg;
+	struct tee_param param[2];
+	u8 *shm_buf;
+	int ret;
+	u32 session_id;
+
+	ret = stm32_bsec_ta_open_session(ctx, &session_id);
+	if (ret)
+		return ret;
+
+	/* Allow only writing complete 32-bits aligned words */
+	if ((bytes % 4) || (offset % 4))
+		return -EINVAL;
+
+	memset(&arg, 0, sizeof(arg));
+	memset(&param, 0, sizeof(param));
+
+	arg.func = PTA_BSEC_WRITE_MEM;
+	arg.session = session_id;
+	arg.num_params = 2;
+
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
+	param[0].u.value.a = offset;
+	param[0].u.value.b = FUSE_ACCESS;
+
+	shm = tee_shm_alloc_kernel_buf(ctx, bytes);
+	if (IS_ERR(shm)) {
+		ret = PTR_ERR(shm);
+		goto out_tee_session;
+	}
+
+	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
+	param[1].u.memref.shm = shm;
+	param[1].u.memref.size = bytes;
+
+	shm_buf = tee_shm_get_va(shm, 0);
+	if (IS_ERR(shm_buf)) {
+		ret = PTR_ERR(shm_buf);
+		pr_err("tee_shm_get_va failed for transmit (%d)\n", ret);
+		tee_shm_free(shm);
+
+		goto out_tee_session;
+	}
+
+	memcpy(shm_buf, buf, bytes);
+
+	ret = tee_client_invoke_func(ctx, &arg, param);
+	if (ret < 0 || arg.ret != 0) {
+		pr_err("TA_BSEC invoke failed TEE err:%#x, ret:%#x\n", arg.ret, ret);
+		if (!ret)
+			ret = -EIO;
+	}
+	pr_debug("Write OTPs %d to %zu, ret=%d\n", offset / 4, (offset + bytes) / 4, ret);
+
+	/* Lock the upper OTPs with ECC protection, word programming only */
+	if (!ret && ((offset + bytes) >= (lower * 4))) {
+		u32 start, nb_lock;
+		u32 *lock = (u32 *)shm_buf;
+		int i;
+
+		/*
+		 * don't lock the lower OTPs, no ECC protection and incremental
+		 * bit programming, a second write is allowed
+		 */
+		start = max_t(u32, offset, lower * 4);
+		nb_lock = (offset + bytes - start) / 4;
+
+		param[0].u.value.a = start;
+		param[0].u.value.b = LOCK_ACCESS;
+		param[1].u.memref.size = nb_lock * 4;
+
+		for (i = 0; i < nb_lock; i++)
+			lock[i] = LOCK_PERM;
+
+		ret = tee_client_invoke_func(ctx, &arg, param);
+		if (ret < 0 || arg.ret != 0) {
+			pr_err("TA_BSEC invoke failed TEE err:%#x, ret:%#x\n", arg.ret, ret);
+			if (!ret)
+				ret = -EIO;
+		}
+		pr_debug("Lock upper OTPs %d to %d, ret=%d\n",
+			 start / 4, start / 4 + nb_lock, ret);
+	}
+
+	tee_shm_free(shm);
+
+out_tee_session:
+	stm32_bsec_ta_close_session(ctx, session_id);
+
+	return ret;
+}