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/*
* omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
*
* Copyright (C) 2009 Nokia Corporation
* Author: Juha Yrjola <juha.yrjola@solidboot.com>
*
* Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/hw_random.h>
#include <linux/workqueue.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#define RNG_RESET 0x01
#define RNG_GEN_PRNG_HW_INIT 0x02
#define RNG_GEN_HW 0x08
/* param1: ptr, param2: count, param3: flag */
static u32 (*omap3_rom_rng_call)(u32, u32, u32);
struct omap_rom_rng {
struct clk *clk;
struct device *dev;
struct hwrng ops;
};
static struct delayed_work idle_work;
static int rng_idle;
static struct clk *rng_clk;
static void omap3_rom_rng_idle(struct work_struct *work)
{
int r;
r = omap3_rom_rng_call(0, 0, RNG_RESET);
if (r != 0) {
pr_err("reset failed: %d\n", r);
return;
}
clk_disable_unprepare(rng_clk);
rng_idle = 1;
}
static int omap3_rom_rng_get_random(void *buf, unsigned int count)
{
u32 r;
u32 ptr;
cancel_delayed_work_sync(&idle_work);
if (rng_idle) {
r = clk_prepare_enable(rng_clk);
if (r)
return r;
r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
if (r != 0) {
clk_disable_unprepare(rng_clk);
pr_err("HW init failed: %d\n", r);
return -EIO;
}
rng_idle = 0;
}
ptr = virt_to_phys(buf);
r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW);
schedule_delayed_work(&idle_work, msecs_to_jiffies(500));
if (r != 0)
return -EINVAL;
return 0;
}
static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
{
int r;
r = omap3_rom_rng_get_random(data, 4);
if (r < 0)
return r;
return 4;
}
static int omap3_rom_rng_probe(struct platform_device *pdev)
{
struct omap_rom_rng *ddata;
int ret = 0;
ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
ddata->dev = &pdev->dev;
ddata->ops.priv = (unsigned long)ddata;
ddata->ops.name = "omap3-rom";
ddata->ops.read = of_device_get_match_data(&pdev->dev);
ddata->ops.quality = 900;
if (!ddata->ops.read) {
dev_err(&pdev->dev, "missing rom code handler\n");
return -ENODEV;
}
dev_set_drvdata(ddata->dev, ddata);
omap3_rom_rng_call = pdev->dev.platform_data;
if (!omap3_rom_rng_call) {
dev_err(ddata->dev, "rom_rng_call is NULL\n");
return -EINVAL;
}
INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle);
ddata->clk = devm_clk_get(ddata->dev, "ick");
if (IS_ERR(ddata->clk)) {
dev_err(ddata->dev, "unable to get RNG clock\n");
return PTR_ERR(ddata->clk);
}
rng_clk = ddata->clk;
/* Leave the RNG in reset state. */
ret = clk_prepare_enable(ddata->clk);
if (ret)
return ret;
omap3_rom_rng_idle(0);
return hwrng_register(&ddata->ops);
}
static int omap3_rom_rng_remove(struct platform_device *pdev)
{
struct omap_rom_rng *ddata;
ddata = dev_get_drvdata(&pdev->dev);
cancel_delayed_work_sync(&idle_work);
hwrng_unregister(&ddata->ops);
if (!rng_idle)
clk_disable_unprepare(rng_clk);
return 0;
}
static const struct of_device_id omap_rom_rng_match[] = {
{ .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
static struct platform_driver omap3_rom_rng_driver = {
.driver = {
.name = "omap3-rom-rng",
.of_match_table = omap_rom_rng_match,
},
.probe = omap3_rom_rng_probe,
.remove = omap3_rom_rng_remove,
};
module_platform_driver(omap3_rom_rng_driver);
MODULE_ALIAS("platform:omap3-rom-rng");
MODULE_AUTHOR("Juha Yrjola");
MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
MODULE_LICENSE("GPL");
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