// SPDX-License-Identifier: GPL-2.0+
/*
 * Allwinner sunXi SoCs Security ID support.
 *
 * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
 * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/device.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/random.h>

struct sunxi_sid_cfg {
	u32	value_offset;
	u32	size;
};

struct sunxi_sid {
	void __iomem		*base;
	u32			value_offset;
};

static int sunxi_sid_read(void *context, unsigned int offset,
			  void *val, size_t bytes)
{
	struct sunxi_sid *sid = context;

	memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes);

	return 0;
}

static int sunxi_sid_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct nvmem_config *nvmem_cfg;
	struct nvmem_device *nvmem;
	struct sunxi_sid *sid;
	int size;
	char *randomness;
	const struct sunxi_sid_cfg *cfg;

	sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
	if (!sid)
		return -ENOMEM;

	cfg = of_device_get_match_data(dev);
	if (!cfg)
		return -EINVAL;
	sid->value_offset = cfg->value_offset;

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

	size = cfg->size;

	nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
	if (!nvmem_cfg)
		return -ENOMEM;

	nvmem_cfg->dev = dev;
	nvmem_cfg->name = "sunxi-sid";
	nvmem_cfg->read_only = true;
	nvmem_cfg->size = cfg->size;
	nvmem_cfg->word_size = 1;
	nvmem_cfg->stride = 4;
	nvmem_cfg->priv = sid;
	nvmem_cfg->reg_read = sunxi_sid_read;

	nvmem = nvmem_register(nvmem_cfg);
	if (IS_ERR(nvmem))
		return PTR_ERR(nvmem);

	randomness = kzalloc(size, GFP_KERNEL);
	if (!randomness)
		return -ENOMEM;

	nvmem_cfg->reg_read(sid, 0, randomness, size);
	add_device_randomness(randomness, size);
	kfree(randomness);

	platform_set_drvdata(pdev, nvmem);

	return 0;
}

static int sunxi_sid_remove(struct platform_device *pdev)
{
	struct nvmem_device *nvmem = platform_get_drvdata(pdev);

	return nvmem_unregister(nvmem);
}

static const struct sunxi_sid_cfg sun50iw9p1_cfg = {
	.value_offset = 0x200,
	.size = 0x100,
};

static const struct sunxi_sid_cfg sun50iw11p1_cfg = {
	.value_offset = 0x200,
	.size = 0x80,
};

static const struct of_device_id sunxi_sid_of_match[] = {
	{ .compatible = "allwinner,sun50iw9p1-sid", .data = &sun50iw9p1_cfg },
	{ .compatible = "allwinner,sun50iw10p1-sid", .data = &sun50iw9p1_cfg },
	{ .compatible = "allwinner,sun50iw11p1-sid", .data = &sun50iw11p1_cfg },
	{ .compatible = "allwinner,sun8iw21p1-sid", .data = &sun50iw9p1_cfg},
	{/* sentinel */},
};
MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);

static struct platform_driver sunxi_sid_driver = {
	.probe = sunxi_sid_probe,
	.remove = sunxi_sid_remove,
	.driver = {
		.name = "eeprom-sunxi-sid",
		.of_match_table = sunxi_sid_of_match,
	},
};
module_platform_driver_paralell(sunxi_sid_driver);

MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
MODULE_DESCRIPTION("Allwinner sunxi security id driver");
MODULE_LICENSE("GPL");