[PATCH v4 2/3] nvmem: stm32: add OP-TEE support for STM32MP13x

[Patrick Delaunay]

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@xxxxxxxxxxx>
---

Changes in v4:
- fixe warning reported by kernel test robot for 64 bits support in
  drivers/nvmem/stm32-bsec-optee-ta.c:260:18:
  warning: format '%d' expects argument of type 'int',
  but argument 4 has type 'size_t'

Changes in v3:
- add a separate file stm32-bsec-optee-ta.c with STM32MP BSEC TA
  communication functions to avoid #if in romem driver.

Changes in v2:
- rebase series on linux-next/master
- minor update after V1 revue
- add missing sentinel in stm32_romem_of_match()
- reorder function and remove prototypes for stm32_bsec_pta... functions
- change stm32_bsec_pta_find to static
- add return value in dev_err()
- cleanups some comments, which can be on one line
- remove test on priv->ctx in stm32_bsec_pta_remove
- add missing tee_shm_free(shm) in stm32_bsec_pta_write() when
  tee_shm_get_va failed
- return error in stm32_bsec_pta_find when devm_add_action_or_reset failed
- handle driver_register error in stm32_romem_init

 drivers/nvmem/Kconfig               |  11 +
 drivers/nvmem/Makefile              |   1 +
 drivers/nvmem/stm32-bsec-optee-ta.c | 298 ++++++++++++++++++++++++++++
 drivers/nvmem/stm32-bsec-optee-ta.h |  80 ++++++++
 drivers/nvmem/stm32-romem.c         |  54 ++++-
 5 files changed, 441 insertions(+), 3 deletions(-)
 create mode 100644 drivers/nvmem/stm32-bsec-optee-ta.c
 create mode 100644 drivers/nvmem/stm32-bsec-optee-ta.h

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 755f551426b5..4d262f69a073 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -290,9 +290,20 @@ config NVMEM_SPRD_EFUSE
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-sprd-efuse.
 
+config NVMEM_STM32_BSEC_OPTEE_TA
+	bool "STM32MP BSEC OP-TEE TA support for nvmem-stm32-romem driver"
+	depends on OPTEE
+	help
+	  Say y here to enable the accesses to STM32MP SoC OTPs by the OP-TEE
+	  trusted application STM32MP BSEC.
+
+	  This library is a used by stm32-romem driver or included in the module
+	  called nvmem-stm32-romem.
+
 config NVMEM_STM32_ROMEM
 	tristate "STMicroelectronics STM32 factory-programmed memory support"
 	depends on ARCH_STM32 || COMPILE_TEST
+	imply NVMEM_STM32_BSEC_OPTEE_TA
 	help
 	  Say y here to enable read-only access for STMicroelectronics STM32
 	  factory-programmed memory area.
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index fa80fe17e567..6a1efffa88f0 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_NVMEM_SPRD_EFUSE)		+= nvmem_sprd_efuse.o
 nvmem_sprd_efuse-y			:= sprd-efuse.o
 obj-$(CONFIG_NVMEM_STM32_ROMEM)		+= nvmem_stm32_romem.o
 nvmem_stm32_romem-y 			:= stm32-romem.o
+nvmem_stm32_romem-$(CONFIG_NVMEM_STM32_BSEC_OPTEE_TA) += stm32-bsec-optee-ta.o
 obj-$(CONFIG_NVMEM_SUNPLUS_OCOTP)	+= nvmem_sunplus_ocotp.o
 nvmem_sunplus_ocotp-y			:= sunplus-ocotp.o
 obj-$(CONFIG_NVMEM_SUNXI_SID)		+= nvmem_sunxi_sid.o
diff --git a/drivers/nvmem/stm32-bsec-optee-ta.c b/drivers/nvmem/stm32-bsec-optee-ta.c
new file mode 100644
index 000000000000..f566d77f632c
--- /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
+ */
+#define PTA_BSEC_READ_MEM		0x0 /* Read OTP */
+
+/*
+ * 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
+ */
+#define PTA_BSEC_WRITE_MEM		0x1	/* Write OTP */
+
+/* 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 BASEC TA presence */
+	rc = stm32_bsec_ta_open_session(tee_ctx, &session_id);
+	if (rc)
+		goto out_tee_session;
+	stm32_bsec_ta_close_session(tee_ctx, session_id);
+
+	*ctx = tee_ctx;
+
+	return 0;
+
+out_tee_session:
+	tee_client_close_context(tee_ctx);
+
+	return rc;
+}
+
+/* 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;
+}
diff --git a/drivers/nvmem/stm32-bsec-optee-ta.h b/drivers/nvmem/stm32-bsec-optee-ta.h
new file mode 100644
index 000000000000..3966a0535179
--- /dev/null
+++ b/drivers/nvmem/stm32-bsec-optee-ta.h
@@ -0,0 +1,80 @@
+/* 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
+ */
+
+#if IS_ENABLED(CONFIG_NVMEM_STM32_BSEC_OPTEE_TA)
+/**
+ * stm32_bsec_optee_ta_open() - initialize the STM32 BSEC TA
+ * @ctx: the OP-TEE context on success
+ *
+ * Return:
+ *	On success, 0. On failure, -errno.
+ */
+int stm32_bsec_optee_ta_open(struct tee_context **ctx);
+
+/**
+ * stm32_bsec_optee_ta_close() - release the STM32 BSEC TA
+ * @ctx: the OP-TEE context
+ *
+ * This function used to clean the OP-TEE resources initialized in
+ * stm32_bsec_optee_ta_open(); it can be used as callback to
+ * devm_add_action_or_reset()
+ */
+void stm32_bsec_optee_ta_close(void *ctx);
+
+/**
+ * stm32_bsec_optee_ta_read() - nvmem read access using TA client driver
+ * @ctx: the OP-TEE context provided by stm32_bsec_optee_ta_open
+ * @offset: nvmem offset
+ * @buf: buffer to fill with nvem values
+ * @bytes: number of bytes to read
+ *
+ * Return:
+ *	On success, 0. On failure, -errno.
+ */
+int stm32_bsec_optee_ta_read(struct tee_context *ctx, unsigned int offset,
+			     void *buf, size_t bytes);
+
+/**
+ * stm32_bsec_optee_ta_write() - nvmem write access using TA client driver
+ * @ctx: the OP-TEE context provided by stm32_bsec_optee_ta_open
+ * @lower: number of lower OTP, not protected by ECC
+ * @offset: nvmem offset
+ * @buf: buffer with nvem values
+ * @bytes: number of bytes to write
+ *
+ * Return:
+ *	On success, 0. On failure, -errno.
+ */
+int stm32_bsec_optee_ta_write(struct tee_context *ctx, unsigned int lower,
+			      unsigned int offset, void *buf, size_t bytes);
+
+#else
+
+static inline int stm32_bsec_optee_ta_open(struct tee_context **ctx)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void stm32_bsec_optee_ta_close(void *ctx)
+{
+}
+
+static inline int stm32_bsec_optee_ta_read(struct tee_context *ctx,
+					   unsigned int offset, void *buf,
+					   size_t bytes)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int stm32_bsec_optee_ta_write(struct tee_context *ctx,
+					    unsigned int lower,
+					    unsigned int offset, void *buf,
+					    size_t bytes)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_NVMEM_STM32_BSEC_OPTEE_TA */
diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index d1d03c2ad081..2edc61925e52 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -11,6 +11,9 @@
 #include <linux/module.h>
 #include <linux/nvmem-provider.h>
 #include <linux/of_device.h>
+#include <linux/tee_drv.h>
+
+#include "stm32-bsec-optee-ta.h"
 
 /* BSEC secure service access from non-secure */
 #define STM32_SMC_BSEC			0x82001003
@@ -25,12 +28,14 @@
 struct stm32_romem_cfg {
 	int size;
 	u8 lower;
+	bool ta;
 };
 
 struct stm32_romem_priv {
 	void __iomem *base;
 	struct nvmem_config cfg;
 	u8 lower;
+	struct tee_context *ctx;
 };
 
 static int stm32_romem_read(void *context, unsigned int offset, void *buf,
@@ -138,12 +143,29 @@ static int stm32_bsec_write(void *context, unsigned int offset, void *buf,
 	return 0;
 }
 
+static int stm32_bsec_pta_read(void *context, unsigned int offset, void *buf,
+			       size_t bytes)
+{
+	struct stm32_romem_priv *priv = context;
+
+	return stm32_bsec_optee_ta_read(priv->ctx, offset, buf, bytes);
+}
+
+static int stm32_bsec_pta_write(void *context, unsigned int offset, void *buf,
+				size_t bytes)
+{
+	struct stm32_romem_priv *priv = context;
+
+	return stm32_bsec_optee_ta_write(priv->ctx, priv->lower, offset, buf, bytes);
+}
+
 static int stm32_romem_probe(struct platform_device *pdev)
 {
 	const struct stm32_romem_cfg *cfg;
 	struct device *dev = &pdev->dev;
 	struct stm32_romem_priv *priv;
 	struct resource *res;
+	int rc;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -173,15 +195,31 @@ static int stm32_romem_probe(struct platform_device *pdev)
 	} else {
 		priv->cfg.size = cfg->size;
 		priv->lower = cfg->lower;
-		priv->cfg.reg_read = stm32_bsec_read;
-		priv->cfg.reg_write = stm32_bsec_write;
+		if (cfg->ta) {
+			rc = stm32_bsec_optee_ta_open(&priv->ctx);
+			/* wait for OP-TEE client driver to be up and ready */
+			if (rc)
+				return rc;
+			rc = devm_add_action_or_reset(dev, stm32_bsec_optee_ta_close, priv->ctx);
+			if (rc) {
+				dev_err(dev, "devm_add_action_or_reset() failed (%d)\n", rc);
+				return rc;
+			}
+		}
+		if (priv->ctx) {
+			priv->cfg.reg_read = stm32_bsec_pta_read;
+			priv->cfg.reg_write = stm32_bsec_pta_write;
+		} else {
+			priv->cfg.reg_read = stm32_bsec_read;
+			priv->cfg.reg_write = stm32_bsec_write;
+		}
 	}
 
 	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &priv->cfg));
 }
 
 /*
- * STM32MP15 BSEC OTP regions: 4096 OTP bits (with 3072 effective bits)
+ * STM32MP15/13 BSEC OTP regions: 4096 OTP bits (with 3072 effective bits)
  * => 96 x 32-bits data words
  * - Lower: 1K bits, 2:1 redundancy, incremental bit programming
  *   => 32 (x 32-bits) lower shadow registers = words 0 to 31
@@ -191,6 +229,13 @@ static int stm32_romem_probe(struct platform_device *pdev)
 static const struct stm32_romem_cfg stm32mp15_bsec_cfg = {
 	.size = 384,
 	.lower = 32,
+	.ta = false,
+};
+
+static const struct stm32_romem_cfg stm32mp13_bsec_cfg = {
+	.size = 384,
+	.lower = 32,
+	.ta = true,
 };
 
 static const struct of_device_id stm32_romem_of_match[] = {
@@ -198,7 +243,10 @@ static const struct of_device_id stm32_romem_of_match[] = {
 		.compatible = "st,stm32mp15-bsec",
 		.data = (void *)&stm32mp15_bsec_cfg,
 	}, {
+		.compatible = "st,stm32mp13-bsec",
+		.data = (void *)&stm32mp13_bsec_cfg,
 	},
+	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, stm32_romem_of_match);
 
-- 
2.25.1