![Alexander Clouter](/assets/img/avatar_default.png)
This patch allows timeriomem_rng to be used via devicetree. Signed-off-by: Alexander Clouter <alex@digriz.org.uk> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
239 lines
5.7 KiB
C
239 lines
5.7 KiB
C
/*
|
|
* drivers/char/hw_random/timeriomem-rng.c
|
|
*
|
|
* Copyright (C) 2009 Alexander Clouter <alex@digriz.org.uk>
|
|
*
|
|
* Derived from drivers/char/hw_random/omap-rng.c
|
|
* Copyright 2005 (c) MontaVista Software, Inc.
|
|
* Author: Deepak Saxena <dsaxena@plexity.net>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* Overview:
|
|
* This driver is useful for platforms that have an IO range that provides
|
|
* periodic random data from a single IO memory address. All the platform
|
|
* has to do is provide the address and 'wait time' that new data becomes
|
|
* available.
|
|
*
|
|
* TODO: add support for reading sizes other than 32bits and masking
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/of.h>
|
|
#include <linux/hw_random.h>
|
|
#include <linux/io.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/timeriomem-rng.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/timer.h>
|
|
#include <linux/completion.h>
|
|
|
|
struct timeriomem_rng_private_data {
|
|
void __iomem *io_base;
|
|
unsigned int expires;
|
|
unsigned int period;
|
|
unsigned int present:1;
|
|
|
|
struct timer_list timer;
|
|
struct completion completion;
|
|
|
|
struct hwrng timeriomem_rng_ops;
|
|
};
|
|
|
|
#define to_rng_priv(rng) \
|
|
((struct timeriomem_rng_private_data *)rng->priv)
|
|
|
|
/*
|
|
* have data return 1, however return 0 if we have nothing
|
|
*/
|
|
static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
|
|
{
|
|
struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
|
|
|
|
if (!wait || priv->present)
|
|
return priv->present;
|
|
|
|
wait_for_completion(&priv->completion);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int timeriomem_rng_data_read(struct hwrng *rng, u32 *data)
|
|
{
|
|
struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
|
|
unsigned long cur;
|
|
s32 delay;
|
|
|
|
*data = readl(priv->io_base);
|
|
|
|
cur = jiffies;
|
|
|
|
delay = cur - priv->expires;
|
|
delay = priv->period - (delay % priv->period);
|
|
|
|
priv->expires = cur + delay;
|
|
priv->present = 0;
|
|
|
|
INIT_COMPLETION(priv->completion);
|
|
mod_timer(&priv->timer, priv->expires);
|
|
|
|
return 4;
|
|
}
|
|
|
|
static void timeriomem_rng_trigger(unsigned long data)
|
|
{
|
|
struct timeriomem_rng_private_data *priv
|
|
= (struct timeriomem_rng_private_data *)data;
|
|
|
|
priv->present = 1;
|
|
complete(&priv->completion);
|
|
}
|
|
|
|
static int timeriomem_rng_probe(struct platform_device *pdev)
|
|
{
|
|
struct timeriomem_rng_data *pdata = pdev->dev.platform_data;
|
|
struct timeriomem_rng_private_data *priv;
|
|
struct resource *res;
|
|
int err = 0;
|
|
int period;
|
|
|
|
if (!pdev->dev.of_node && !pdata) {
|
|
dev_err(&pdev->dev, "timeriomem_rng_data is missing\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
if (!res)
|
|
return -ENXIO;
|
|
|
|
if (res->start % 4 != 0 || resource_size(res) != 4) {
|
|
dev_err(&pdev->dev,
|
|
"address must be four bytes wide and aligned\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Allocate memory for the device structure (and zero it) */
|
|
priv = kzalloc(sizeof(struct timeriomem_rng_private_data), GFP_KERNEL);
|
|
if (!priv) {
|
|
dev_err(&pdev->dev, "failed to allocate device structure.\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
platform_set_drvdata(pdev, priv);
|
|
|
|
if (pdev->dev.of_node) {
|
|
int i;
|
|
|
|
if (!of_property_read_u32(pdev->dev.of_node,
|
|
"period", &i))
|
|
period = i;
|
|
else {
|
|
dev_err(&pdev->dev, "missing period\n");
|
|
err = -EINVAL;
|
|
goto out_free;
|
|
}
|
|
} else
|
|
period = pdata->period;
|
|
|
|
priv->period = usecs_to_jiffies(period);
|
|
if (priv->period < 1) {
|
|
dev_err(&pdev->dev, "period is less than one jiffy\n");
|
|
err = -EINVAL;
|
|
goto out_free;
|
|
}
|
|
|
|
priv->expires = jiffies;
|
|
priv->present = 1;
|
|
|
|
init_completion(&priv->completion);
|
|
complete(&priv->completion);
|
|
|
|
setup_timer(&priv->timer, timeriomem_rng_trigger, (unsigned long)priv);
|
|
|
|
priv->timeriomem_rng_ops.name = dev_name(&pdev->dev);
|
|
priv->timeriomem_rng_ops.data_present = timeriomem_rng_data_present;
|
|
priv->timeriomem_rng_ops.data_read = timeriomem_rng_data_read;
|
|
priv->timeriomem_rng_ops.priv = (unsigned long)priv;
|
|
|
|
if (!request_mem_region(res->start, resource_size(res),
|
|
dev_name(&pdev->dev))) {
|
|
dev_err(&pdev->dev, "request_mem_region failed\n");
|
|
err = -EBUSY;
|
|
goto out_timer;
|
|
}
|
|
|
|
priv->io_base = ioremap(res->start, resource_size(res));
|
|
if (priv->io_base == NULL) {
|
|
dev_err(&pdev->dev, "ioremap failed\n");
|
|
err = -EIO;
|
|
goto out_release_io;
|
|
}
|
|
|
|
err = hwrng_register(&priv->timeriomem_rng_ops);
|
|
if (err) {
|
|
dev_err(&pdev->dev, "problem registering\n");
|
|
goto out;
|
|
}
|
|
|
|
dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
|
|
priv->io_base, period);
|
|
|
|
return 0;
|
|
|
|
out:
|
|
iounmap(priv->io_base);
|
|
out_release_io:
|
|
release_mem_region(res->start, resource_size(res));
|
|
out_timer:
|
|
del_timer_sync(&priv->timer);
|
|
out_free:
|
|
platform_set_drvdata(pdev, NULL);
|
|
kfree(priv);
|
|
return err;
|
|
}
|
|
|
|
static int timeriomem_rng_remove(struct platform_device *pdev)
|
|
{
|
|
struct timeriomem_rng_private_data *priv = platform_get_drvdata(pdev);
|
|
struct resource *res;
|
|
|
|
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
|
|
hwrng_unregister(&priv->timeriomem_rng_ops);
|
|
|
|
del_timer_sync(&priv->timer);
|
|
iounmap(priv->io_base);
|
|
release_mem_region(res->start, resource_size(res));
|
|
platform_set_drvdata(pdev, NULL);
|
|
kfree(priv);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id timeriomem_rng_match[] = {
|
|
{ .compatible = "timeriomem_rng" },
|
|
{},
|
|
};
|
|
MODULE_DEVICE_TABLE(of, timeriomem_rng_match);
|
|
|
|
static struct platform_driver timeriomem_rng_driver = {
|
|
.driver = {
|
|
.name = "timeriomem_rng",
|
|
.owner = THIS_MODULE,
|
|
.of_match_table = timeriomem_rng_match,
|
|
},
|
|
.probe = timeriomem_rng_probe,
|
|
.remove = timeriomem_rng_remove,
|
|
};
|
|
|
|
module_platform_driver(timeriomem_rng_driver);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
|
|
MODULE_DESCRIPTION("Timer IOMEM H/W RNG driver");
|