drivers/nvmem/stm32-romem.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * STM32 Factory-programmed memory read access driver
  *
  * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
  * Author: Fabrice Gasnier <fabrice.gasnier@st.com> for STMicroelectronics.
  */

 #include <linux/arm-smccc.h>
 #include <linux/io.h>
 #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
 #define STM32_SMC_READ_SHADOW		0x01
 #define STM32_SMC_PROG_OTP		0x02
 #define STM32_SMC_WRITE_SHADOW		0x03
 #define STM32_SMC_READ_OTP		0x04

 /* shadow registers offset */
 #define STM32MP15_BSEC_DATA0		0x200

 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,
 			    size_t bytes)
 {
 	struct stm32_romem_priv *priv = context;
 	u8 *buf8 = buf;
 	int i;

 	for (i = offset; i < offset + bytes; i++)
 		*buf8++ = readb_relaxed(priv->base + i);

 	return 0;
 }

 static int stm32_bsec_smc(u8 op, u32 otp, u32 data, u32 *result)
 {
 #if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC)
 	struct arm_smccc_res res;

 	arm_smccc_smc(STM32_SMC_BSEC, op, otp, data, 0, 0, 0, 0, &res);
 	if (res.a0)
 		return -EIO;

 	if (result)
 		*result = (u32)res.a1;

 	return 0;
 #else
 	return -ENXIO;
 #endif
 }

 static int stm32_bsec_read(void *context, unsigned int offset, void *buf,
 			   size_t bytes)
 {
 	struct stm32_romem_priv *priv = context;
 	struct device *dev = priv->cfg.dev;
 	u32 roffset, rbytes, val;
 	u8 *buf8 = buf, *val8 = (u8 *)&val;
 	int i, j = 0, ret, skip_bytes, size;

 	/* Round unaligned access to 32-bits */
 	roffset = rounddown(offset, 4);
 	skip_bytes = offset & 0x3;
 	rbytes = roundup(bytes + skip_bytes, 4);

 	if (roffset + rbytes > priv->cfg.size)
 		return -EINVAL;

 	for (i = roffset; (i < roffset + rbytes); i += 4) {
 		u32 otp = i >> 2;

 		if (otp < priv->lower) {
 			/* read lower data from shadow registers */
 			val = readl_relaxed(
 				priv->base + STM32MP15_BSEC_DATA0 + i);
 		} else {
 			ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, otp, 0,
 					     &val);
 			if (ret) {
 				dev_err(dev, "Can't read data%d (%d)\n", otp,
 					ret);
 				return ret;
 			}
 		}
 		/* skip first bytes in case of unaligned read */
 		if (skip_bytes)
 			size = min(bytes, (size_t)(4 - skip_bytes));
 		else
 			size = min(bytes, (size_t)4);
 		memcpy(&buf8[j], &val8[skip_bytes], size);
 		bytes -= size;
 		j += size;
 		skip_bytes = 0;
 	}

 	return 0;
 }

 static int stm32_bsec_write(void *context, unsigned int offset, void *buf,
 			    size_t bytes)
 {
 	struct stm32_romem_priv *priv = context;
 	struct device *dev = priv->cfg.dev;
 	u32 *buf32 = buf;
 	int ret, i;

 	/* Allow only writing complete 32-bits aligned words */
 	if ((bytes % 4) || (offset % 4))
 		return -EINVAL;

 	for (i = offset; i < offset + bytes; i += 4) {
 		ret = stm32_bsec_smc(STM32_SMC_PROG_OTP, i >> 2, *buf32++,
 				     NULL);
 		if (ret) {
 			dev_err(dev, "Can't write data%d (%d)\n", i >> 2, ret);
 			return ret;
 		}
 	}

 	if (offset + bytes >= priv->lower * 4)
 		dev_warn(dev, "Update of upper OTPs with ECC protection (word programming, only once)\n");

 	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 bool stm32_bsec_smc_check(void)
 {
 	u32 val;
 	int ret;

 	/* check that the OP-TEE support the BSEC SMC (legacy mode) */
 	ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, 0, 0, &val);

 	return !ret;
 }

 static bool optee_presence_check(void)
 {
 	struct device_node *np;
 	bool tee_detected = false;

 	/* check that the OP-TEE node is present and available. */
 	np = of_find_compatible_node(NULL, NULL, "linaro,optee-tz");
 	if (np && of_device_is_available(np))
 		tee_detected = true;
 	of_node_put(np);

 	return tee_detected;
 }

 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)
 		return -ENOMEM;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	priv->base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);

 	priv->cfg.name = "stm32-romem";
 	priv->cfg.word_size = 1;
 	priv->cfg.stride = 1;
 	priv->cfg.dev = dev;
 	priv->cfg.priv = priv;
 	priv->cfg.owner = THIS_MODULE;
 	priv->cfg.type = NVMEM_TYPE_OTP;

 	priv->lower = 0;

 	cfg = (const struct stm32_romem_cfg *)
 		of_match_device(dev->driver->of_match_table, dev)->data;
 	if (!cfg) {
 		priv->cfg.read_only = true;
 		priv->cfg.size = resource_size(res);
 		priv->cfg.reg_read = stm32_romem_read;
 	} else {
 		priv->cfg.size = cfg->size;
 		priv->lower = cfg->lower;
 		if (cfg->ta || optee_presence_check()) {
 			rc = stm32_bsec_optee_ta_open(&priv->ctx);
 			if (rc) {
 				/* wait for OP-TEE client driver to be up and ready */
 				if (rc == -EPROBE_DEFER)
 					return -EPROBE_DEFER;
 				/* BSEC PTA is required or SMC not supported */
 				if (cfg->ta || !stm32_bsec_smc_check())
 					return rc;
 			}
 		}
 		if (priv->ctx) {
 			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;
 			}
 			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));
 }

 /*
  * STM32MP15/13 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
  * - Upper: 2K bits, ECC protection, word programming only
  *   => 64 (x 32-bits) = words 32 to 95
  */
 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[] __maybe_unused = {
 	{ .compatible = "st,stm32f4-otp", }, {
 		.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);

 static struct platform_driver stm32_romem_driver = {
 	.probe = stm32_romem_probe,
 	.driver = {
 		.name = "stm32-romem",
 		.of_match_table = of_match_ptr(stm32_romem_of_match),
 	},
 };
 module_platform_driver(stm32_romem_driver);

 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 MODULE_DESCRIPTION("STMicroelectronics STM32 RO-MEM");
 MODULE_ALIAS("platform:nvmem-stm32-romem");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* STM32 Factory-programmed memory read access driver
	*
	* Copyright (C) 2017, STMicroelectronics - All Rights Reserved
	* Author: Fabrice Gasnier <fabrice.gasnier@st.com> for STMicroelectronics.
	*/

	#include <linux/arm-smccc.h>
	#include <linux/io.h>
	#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
	#define STM32_SMC_READ_SHADOW 0x01
	#define STM32_SMC_PROG_OTP 0x02
	#define STM32_SMC_WRITE_SHADOW 0x03
	#define STM32_SMC_READ_OTP 0x04

	/* shadow registers offset */
	#define STM32MP15_BSEC_DATA0 0x200

	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,
	size_t bytes)
	{
	struct stm32_romem_priv *priv = context;
	u8 *buf8 = buf;
	int i;

	for (i = offset; i < offset + bytes; i++)
	*buf8++ = readb_relaxed(priv->base + i);

	return 0;
	}

	static int stm32_bsec_smc(u8 op, u32 otp, u32 data, u32 *result)
	{
	#if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC)
	struct arm_smccc_res res;

	arm_smccc_smc(STM32_SMC_BSEC, op, otp, data, 0, 0, 0, 0, &res);
	if (res.a0)
	return -EIO;

	if (result)
	*result = (u32)res.a1;

	return 0;
	#else
	return -ENXIO;
	#endif
	}

	static int stm32_bsec_read(void context, unsigned int offset, void buf,
	size_t bytes)
	{
	struct stm32_romem_priv *priv = context;
	struct device *dev = priv->cfg.dev;
	u32 roffset, rbytes, val;
	u8 buf8 = buf, val8 = (u8 *)&val;
	int i, j = 0, ret, skip_bytes, size;

	/* Round unaligned access to 32-bits */
	roffset = rounddown(offset, 4);
	skip_bytes = offset & 0x3;
	rbytes = roundup(bytes + skip_bytes, 4);

	if (roffset + rbytes > priv->cfg.size)
	return -EINVAL;

	for (i = roffset; (i < roffset + rbytes); i += 4) {
	u32 otp = i >> 2;

	if (otp < priv->lower) {
	/* read lower data from shadow registers */
	val = readl_relaxed(
	priv->base + STM32MP15_BSEC_DATA0 + i);
	} else {
	ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, otp, 0,
	&val);
	if (ret) {
	dev_err(dev, "Can't read data%d (%d)\n", otp,
	ret);
	return ret;
	}
	}
	/* skip first bytes in case of unaligned read */
	if (skip_bytes)
	size = min(bytes, (size_t)(4 - skip_bytes));
	else
	size = min(bytes, (size_t)4);
	memcpy(&buf8[j], &val8[skip_bytes], size);
	bytes -= size;
	j += size;
	skip_bytes = 0;
	}

	return 0;
	}

	static int stm32_bsec_write(void context, unsigned int offset, void buf,
	size_t bytes)
	{
	struct stm32_romem_priv *priv = context;
	struct device *dev = priv->cfg.dev;
	u32 *buf32 = buf;
	int ret, i;

	/* Allow only writing complete 32-bits aligned words */
	if ((bytes % 4) \|\| (offset % 4))
	return -EINVAL;

	for (i = offset; i < offset + bytes; i += 4) {
	ret = stm32_bsec_smc(STM32_SMC_PROG_OTP, i >> 2, *buf32++,
	NULL);
	if (ret) {
	dev_err(dev, "Can't write data%d (%d)\n", i >> 2, ret);
	return ret;
	}
	}

	if (offset + bytes >= priv->lower * 4)
	dev_warn(dev, "Update of upper OTPs with ECC protection (word programming, only once)\n");

	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 bool stm32_bsec_smc_check(void)
	{
	u32 val;
	int ret;

	/* check that the OP-TEE support the BSEC SMC (legacy mode) */
	ret = stm32_bsec_smc(STM32_SMC_READ_SHADOW, 0, 0, &val);

	return !ret;
	}

	static bool optee_presence_check(void)
	{
	struct device_node *np;
	bool tee_detected = false;

	/* check that the OP-TEE node is present and available. */
	np = of_find_compatible_node(NULL, NULL, "linaro,optee-tz");
	if (np && of_device_is_available(np))
	tee_detected = true;
	of_node_put(np);

	return tee_detected;
	}

	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)
	return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	priv->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(priv->base))
	return PTR_ERR(priv->base);

	priv->cfg.name = "stm32-romem";
	priv->cfg.word_size = 1;
	priv->cfg.stride = 1;
	priv->cfg.dev = dev;
	priv->cfg.priv = priv;
	priv->cfg.owner = THIS_MODULE;
	priv->cfg.type = NVMEM_TYPE_OTP;

	priv->lower = 0;

	cfg = (const struct stm32_romem_cfg *)
	of_match_device(dev->driver->of_match_table, dev)->data;
	if (!cfg) {
	priv->cfg.read_only = true;
	priv->cfg.size = resource_size(res);
	priv->cfg.reg_read = stm32_romem_read;
	} else {
	priv->cfg.size = cfg->size;
	priv->lower = cfg->lower;
	if (cfg->ta \|\| optee_presence_check()) {
	rc = stm32_bsec_optee_ta_open(&priv->ctx);
	if (rc) {
	/* wait for OP-TEE client driver to be up and ready */
	if (rc == -EPROBE_DEFER)
	return -EPROBE_DEFER;
	/* BSEC PTA is required or SMC not supported */
	if (cfg->ta \|\| !stm32_bsec_smc_check())
	return rc;
	}
	}
	if (priv->ctx) {
	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;
	}
	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));
	}

	/*
	* STM32MP15/13 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
	* - Upper: 2K bits, ECC protection, word programming only
	* => 64 (x 32-bits) = words 32 to 95
	*/
	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[] __maybe_unused = {
	{ .compatible = "st,stm32f4-otp", }, {
	.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);

	static struct platform_driver stm32_romem_driver = {
	.probe = stm32_romem_probe,
	.driver = {
	.name = "stm32-romem",
	.of_match_table = of_match_ptr(stm32_romem_of_match),
	},
	};
	module_platform_driver(stm32_romem_driver);

	MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
	MODULE_DESCRIPTION("STMicroelectronics STM32 RO-MEM");
	MODULE_ALIAS("platform:nvmem-stm32-romem");
	MODULE_LICENSE("GPL v2");