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hwrng: timeriomem - update to support more than one device
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timeriomem_rng only supports a single device instance.  This patch
enables multiple timeriomem_rng devices to coexist as well as adds
some additional error checking.

Signed-off-by: Alexander Clouter <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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@jimdigriz @herbertx
jimdigriz authored and herbertx committed Apr 25, 2013
1 parent 57ae1b0 commit 1907da7
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Showing 2 changed files with 116 additions and 59 deletions.
170 changes: 116 additions & 54 deletions drivers/char/hw_random/timeriomem-rng.c
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Expand Up @@ -25,117 +25,179 @@
#include <linux/platform_device.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>

static struct timeriomem_rng_data *timeriomem_rng_data;
struct timeriomem_rng_private_data {
void __iomem *io_base;
unsigned int expires;
unsigned int period;
unsigned int present:1;

static void timeriomem_rng_trigger(unsigned long);
static DEFINE_TIMER(timeriomem_rng_timer, timeriomem_rng_trigger, 0, 0);
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)
{
if (rng->priv == 0)
return 1;
struct timeriomem_rng_private_data *priv = to_rng_priv(rng);

if (!wait || timeriomem_rng_data->present)
return timeriomem_rng_data->present;
if (!wait || priv->present)
return priv->present;

wait_for_completion(&timeriomem_rng_data->completion);
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(timeriomem_rng_data->address);
*data = readl(priv->io_base);

if (rng->priv != 0) {
cur = jiffies;
cur = jiffies;

delay = cur - timeriomem_rng_timer.expires;
delay = rng->priv - (delay % rng->priv);
delay = cur - priv->expires;
delay = priv->period - (delay % priv->period);

timeriomem_rng_timer.expires = cur + delay;
timeriomem_rng_data->present = 0;
priv->expires = cur + delay;
priv->present = 0;

init_completion(&timeriomem_rng_data->completion);
add_timer(&timeriomem_rng_timer);
}
INIT_COMPLETION(priv->completion);
mod_timer(&priv->timer, priv->expires);

return 4;
}

static void timeriomem_rng_trigger(unsigned long dummy)
static void timeriomem_rng_trigger(unsigned long data)
{
timeriomem_rng_data->present = 1;
complete(&timeriomem_rng_data->completion);
}
struct timeriomem_rng_private_data *priv
= (struct timeriomem_rng_private_data *)data;

static struct hwrng timeriomem_rng_ops = {
.name = "timeriomem",
.data_present = timeriomem_rng_data_present,
.data_read = timeriomem_rng_data_read,
.priv = 0,
};
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 ret;
int err = 0;
int period;

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!pdata) {
dev_err(&pdev->dev, "timeriomem_rng_data is missing\n");
return -EINVAL;
}

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
return -ENXIO;

timeriomem_rng_data = pdev->dev.platform_data;
if (res->start % 4 != 0 || resource_size(res) != 4) {
dev_err(&pdev->dev,
"address must be four bytes wide and aligned\n");
return -EINVAL;
}

timeriomem_rng_data->address = ioremap(res->start, resource_size(res));
if (!timeriomem_rng_data->address)
return -EIO;
/* 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 (timeriomem_rng_data->period != 0
&& usecs_to_jiffies(timeriomem_rng_data->period) > 0) {
timeriomem_rng_timer.expires = jiffies;
period = pdata->period;

timeriomem_rng_ops.priv = usecs_to_jiffies(
timeriomem_rng_data->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;
}
timeriomem_rng_data->present = 1;

ret = hwrng_register(&timeriomem_rng_ops);
if (ret)
goto failed;
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",
timeriomem_rng_data->address,
timeriomem_rng_data->period);
priv->io_base, period);

return 0;

failed:
dev_err(&pdev->dev, "problem registering\n");
iounmap(timeriomem_rng_data->address);

return ret;
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)
{
del_timer_sync(&timeriomem_rng_timer);
hwrng_unregister(&timeriomem_rng_ops);
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);

iounmap(timeriomem_rng_data->address);
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;
}
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5 changes: 0 additions & 5 deletions include/linux/timeriomem-rng.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,7 @@
* published by the Free Software Foundation.
*/

#include <linux/completion.h>

struct timeriomem_rng_data {
struct completion completion;
unsigned int present:1;

void __iomem *address;

/* measures in usecs */
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