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/*
* Copyright (c) 2015, Daniel Thompson
*
* This file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This file is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/slab.h>
#define RNG_CR 0x00
#define RNG_CR_RNGEN BIT(2)
#define RNG_CR_CED BIT(5)
#define RNG_SR 0x04
#define RNG_SR_SEIS BIT(6)
#define RNG_SR_CEIS BIT(5)
#define RNG_SR_DRDY BIT(0)
#define RNG_DR 0x08
struct stm32_rng_private {
struct hwrng rng;
void __iomem *base;
struct clk *clk;
struct reset_control *rst;
bool ced;
};
static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
struct stm32_rng_private *priv =
container_of(rng, struct stm32_rng_private, rng);
u32 sr;
int retval = 0;
pm_runtime_get_sync((struct device *) priv->rng.priv);
while (max > sizeof(u32)) {
sr = readl_relaxed(priv->base + RNG_SR);
/* Manage timeout which is based on timer and take */
/* care of initial delay time when enabling rng */
if (!sr && wait) {
retval = readl_relaxed_poll_timeout_atomic(priv->base
+ RNG_SR,
sr, sr,
10, 50000);
if (retval)
dev_err((struct device *)priv->rng.priv,
"%s: timeout %x!\n", __func__, sr);
}
/* If error detected or data not ready... */
if (sr != RNG_SR_DRDY) {
if (WARN_ONCE(sr & (RNG_SR_SEIS | RNG_SR_CEIS),
"bad RNG status - %x\n", sr))
writel_relaxed(0, priv->base + RNG_SR);
break;
}
*(u32 *)data = readl_relaxed(priv->base + RNG_DR);
retval += sizeof(u32);
data += sizeof(u32);
max -= sizeof(u32);
}
pm_runtime_mark_last_busy((struct device *) priv->rng.priv);
pm_runtime_put_sync_autosuspend((struct device *) priv->rng.priv);
return retval || !wait ? retval : -EIO;
}
static int stm32_rng_init(struct hwrng *rng)
{
struct stm32_rng_private *priv =
container_of(rng, struct stm32_rng_private, rng);
int err;
err = clk_prepare_enable(priv->clk);
if (err)
return err;
if (priv->ced)
writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR);
else
writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED,
priv->base + RNG_CR);
/* clear error indicators */
writel_relaxed(0, priv->base + RNG_SR);
return 0;
}
static void stm32_rng_cleanup(struct hwrng *rng)
{
struct stm32_rng_private *priv =
container_of(rng, struct stm32_rng_private, rng);
writel_relaxed(0, priv->base + RNG_CR);
clk_disable_unprepare(priv->clk);
}
static int stm32_rng_probe(struct platform_device *ofdev)
{
struct device *dev = &ofdev->dev;
struct device_node *np = ofdev->dev.of_node;
struct stm32_rng_private *priv;
struct resource res;
int err;
priv = devm_kzalloc(dev, sizeof(struct stm32_rng_private), GFP_KERNEL);
if (!priv)
return -ENOMEM;
err = of_address_to_resource(np, 0, &res);
if (err)
return err;
priv->base = devm_ioremap_resource(dev, &res);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
priv->clk = devm_clk_get(&ofdev->dev, NULL);
if (IS_ERR(priv->clk))
return PTR_ERR(priv->clk);
priv->rst = devm_reset_control_get(&ofdev->dev, NULL);
if (!IS_ERR(priv->rst)) {
reset_control_assert(priv->rst);
udelay(2);
reset_control_deassert(priv->rst);
}
priv->ced = of_property_read_bool(np, "clock-error-detect");
dev_set_drvdata(dev, priv);
priv->rng.name = dev_driver_string(dev),
#ifndef CONFIG_PM
priv->rng.init = stm32_rng_init,
priv->rng.cleanup = stm32_rng_cleanup,
#endif
priv->rng.read = stm32_rng_read,
priv->rng.priv = (unsigned long) dev;
pm_runtime_set_autosuspend_delay(dev, 100);
pm_runtime_use_autosuspend(dev);
pm_runtime_enable(dev);
return devm_hwrng_register(dev, &priv->rng);
}
#ifdef CONFIG_PM
static int stm32_rng_runtime_suspend(struct device *dev)
{
struct stm32_rng_private *priv = dev_get_drvdata(dev);
stm32_rng_cleanup(&priv->rng);
return 0;
}
static int stm32_rng_runtime_resume(struct device *dev)
{
struct stm32_rng_private *priv = dev_get_drvdata(dev);
return stm32_rng_init(&priv->rng);
}
#endif
static const struct dev_pm_ops stm32_rng_pm_ops = {
SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend,
stm32_rng_runtime_resume, NULL)
SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
pm_runtime_force_resume)
};
static const struct of_device_id stm32_rng_match[] = {
{
.compatible = "st,stm32-rng",
},
{},
};
MODULE_DEVICE_TABLE(of, stm32_rng_match);
static struct platform_driver stm32_rng_driver = {
.driver = {
.name = "stm32-rng",
.pm = &stm32_rng_pm_ops,
.of_match_table = stm32_rng_match,
},
.probe = stm32_rng_probe,
};
module_platform_driver(stm32_rng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Daniel Thompson <daniel.thompson@linaro.org>");
MODULE_DESCRIPTION("STMicroelectronics STM32 RNG device driver");
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