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// 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>
/* 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;
};
struct stm32_romem_priv {
void __iomem *base;
struct nvmem_config cfg;
u8 lower;
};
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_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;
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;
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)
* => 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,
};
static const struct of_device_id stm32_romem_of_match[] = {
{ .compatible = "st,stm32f4-otp", }, {
.compatible = "st,stm32mp15-bsec",
.data = (void *)&stm32mp15_bsec_cfg,
}, {
},
};
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");
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