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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.
*/
#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>
#include <linux/pm_runtime.h>
#define RNG_RESET 0x01
#define RNG_GEN_PRNG_HW_INIT 0x02
#define RNG_GEN_HW 0x08
struct omap_rom_rng {
struct clk *clk;
struct device *dev;
struct hwrng ops;
u32 (*rom_rng_call)(u32 ptr, u32 count, u32 flag);
};
static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
{
struct omap_rom_rng *ddata;
u32 ptr;
int r;
ddata = (struct omap_rom_rng *)rng->priv;
r = pm_runtime_get_sync(ddata->dev);
if (r < 0) {
pm_runtime_put_noidle(ddata->dev);
return r;
}
ptr = virt_to_phys(data);
r = ddata->rom_rng_call(ptr, 4, RNG_GEN_HW);
if (r != 0)
r = -EINVAL;
else
r = 4;
pm_runtime_mark_last_busy(ddata->dev);
pm_runtime_put_autosuspend(ddata->dev);
return r;
}
static int omap_rom_rng_runtime_suspend(struct device *dev)
{
struct omap_rom_rng *ddata;
int r;
ddata = dev_get_drvdata(dev);
r = ddata->rom_rng_call(0, 0, RNG_RESET);
if (r != 0)
dev_err(dev, "reset failed: %d\n", r);
clk_disable_unprepare(ddata->clk);
return 0;
}
static int omap_rom_rng_runtime_resume(struct device *dev)
{
struct omap_rom_rng *ddata;
int r;
ddata = dev_get_drvdata(dev);
r = clk_prepare_enable(ddata->clk);
if (r < 0)
return r;
r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
if (r != 0) {
clk_disable(ddata->clk);
dev_err(dev, "HW init failed: %d\n", r);
return -EIO;
}
return 0;
}
static void omap_rom_rng_finish(void *data)
{
struct omap_rom_rng *ddata = data;
pm_runtime_dont_use_autosuspend(ddata->dev);
pm_runtime_disable(ddata->dev);
}
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);
ddata->rom_rng_call = pdev->dev.platform_data;
if (!ddata->rom_rng_call) {
dev_err(ddata->dev, "rom_rng_call is NULL\n");
return -EINVAL;
}
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);
}
pm_runtime_enable(&pdev->dev);
pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
pm_runtime_use_autosuspend(&pdev->dev);
ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish,
ddata);
if (ret)
return ret;
return devm_hwrng_register(ddata->dev, &ddata->ops);
}
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 const struct dev_pm_ops omap_rom_rng_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend,
omap_rom_rng_runtime_resume)
};
static struct platform_driver omap3_rom_rng_driver = {
.driver = {
.name = "omap3-rom-rng",
.of_match_table = omap_rom_rng_match,
.pm = &omap_rom_rng_pm_ops,
},
.probe = omap3_rom_rng_probe,
};
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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