1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
new file mode 100644
index 0000000000..0f84044bd1
--- /dev/null
+++ b/drivers/nvmem/stm32-romem.c
@@ -0,0 +1,294 @@
+// 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;
+
+	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &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");