c3277f8ee8
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>
100 lines
2.2 KiB
C
100 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* sfr.c - driver for special function registers
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*
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* Copyright (C) 2019 Bootlin.
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*
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*/
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#include <linux/mfd/syscon.h>
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#include <linux/module.h>
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#include <linux/nvmem-provider.h>
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#include <linux/random.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#define SFR_SN0 0x4c
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#define SFR_SN_SIZE 8
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struct atmel_sfr_priv {
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struct regmap *regmap;
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};
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static int atmel_sfr_read(void *context, unsigned int offset,
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void *buf, size_t bytes)
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{
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struct atmel_sfr_priv *priv = context;
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return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
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buf, bytes / 4);
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}
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static struct nvmem_config atmel_sfr_nvmem_config = {
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.name = "atmel-sfr",
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.read_only = true,
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.word_size = 4,
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.stride = 4,
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.size = SFR_SN_SIZE,
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.reg_read = atmel_sfr_read,
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};
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static int atmel_sfr_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->of_node;
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struct nvmem_device *nvmem;
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struct atmel_sfr_priv *priv;
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u8 sn[SFR_SN_SIZE];
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int ret;
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priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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priv->regmap = syscon_node_to_regmap(np);
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if (IS_ERR(priv->regmap)) {
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dev_err(dev, "cannot get parent's regmap\n");
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return PTR_ERR(priv->regmap);
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}
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atmel_sfr_nvmem_config.dev = dev;
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atmel_sfr_nvmem_config.priv = priv;
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nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
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if (IS_ERR(nvmem)) {
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dev_err(dev, "error registering nvmem config\n");
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return PTR_ERR(nvmem);
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}
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ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
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if (ret == 0)
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add_device_randomness(sn, SFR_SN_SIZE);
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return ret;
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}
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static const struct of_device_id atmel_sfr_dt_ids[] = {
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{
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.compatible = "atmel,sama5d2-sfr",
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}, {
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.compatible = "atmel,sama5d4-sfr",
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}, {
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/* sentinel */
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},
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};
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MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
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static struct platform_driver atmel_sfr_driver = {
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.probe = atmel_sfr_probe,
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.driver = {
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.name = "atmel-sfr",
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.of_match_table = atmel_sfr_dt_ids,
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},
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};
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module_platform_driver(atmel_sfr_driver);
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MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
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MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
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MODULE_LICENSE("GPL v2");
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