linux/drivers/soc/atmel/sfr.c
Kamel Bouhara c3277f8ee8 soc: at91: Add Atmel SFR SN (Serial Number) support
Add support to read SFR's read-only registers providing the SoC
Serial Numbers (SN0+SN1) to userspace.

~ #  hexdump -n 8  -e'"%d\n"' /sys/bus/nvmem/devices/atmel-sfr0/nvmem
959527243
371539274

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Tested-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20191004151802.21793-1-kamel.bouhara@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-11-07 22:33:10 +01:00

100 lines
2.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* sfr.c - driver for special function registers
*
* Copyright (C) 2019 Bootlin.
*
*/
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/random.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#define SFR_SN0 0x4c
#define SFR_SN_SIZE 8
struct atmel_sfr_priv {
struct regmap *regmap;
};
static int atmel_sfr_read(void *context, unsigned int offset,
void *buf, size_t bytes)
{
struct atmel_sfr_priv *priv = context;
return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
buf, bytes / 4);
}
static struct nvmem_config atmel_sfr_nvmem_config = {
.name = "atmel-sfr",
.read_only = true,
.word_size = 4,
.stride = 4,
.size = SFR_SN_SIZE,
.reg_read = atmel_sfr_read,
};
static int atmel_sfr_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct nvmem_device *nvmem;
struct atmel_sfr_priv *priv;
u8 sn[SFR_SN_SIZE];
int ret;
priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->regmap = syscon_node_to_regmap(np);
if (IS_ERR(priv->regmap)) {
dev_err(dev, "cannot get parent's regmap\n");
return PTR_ERR(priv->regmap);
}
atmel_sfr_nvmem_config.dev = dev;
atmel_sfr_nvmem_config.priv = priv;
nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
if (IS_ERR(nvmem)) {
dev_err(dev, "error registering nvmem config\n");
return PTR_ERR(nvmem);
}
ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
if (ret == 0)
add_device_randomness(sn, SFR_SN_SIZE);
return ret;
}
static const struct of_device_id atmel_sfr_dt_ids[] = {
{
.compatible = "atmel,sama5d2-sfr",
}, {
.compatible = "atmel,sama5d4-sfr",
}, {
/* sentinel */
},
};
MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
static struct platform_driver atmel_sfr_driver = {
.probe = atmel_sfr_probe,
.driver = {
.name = "atmel-sfr",
.of_match_table = atmel_sfr_dt_ids,
},
};
module_platform_driver(atmel_sfr_driver);
MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
MODULE_LICENSE("GPL v2");