107 lines
2.3 KiB
C
107 lines
2.3 KiB
C
|
/*
|
||
|
|
* Nomadik RNG support
|
||
|
|
* Copyright 2009 Alessandro Rubini
|
||
|
|
*
|
||
|
|
* This program 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/device.h>
|
||
|
|
#include <linux/amba/bus.h>
|
||
|
|
#include <linux/hw_random.h>
|
||
|
|
#include <linux/io.h>
|
||
|
|
#include <linux/clk.h>
|
||
|
|
#include <linux/err.h>
|
||
|
|
|
||
|
|
static struct clk *rng_clk;
|
||
|
|
|
||
|
|
static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
|
||
|
|
{
|
||
|
|
void __iomem *base = (void __iomem *)rng->priv;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* The register is 32 bits and gives 16 random bits (low half).
|
||
|
|
* A subsequent read will delay the core for 400ns, so we just read
|
||
|
|
* once and accept the very unlikely very small delay, even if wait==0.
|
||
|
|
*/
|
||
|
|
*(u16 *)data = __raw_readl(base + 8) & 0xffff;
|
||
|
|
return 2;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* we have at most one RNG per machine, granted */
|
||
|
|
static struct hwrng nmk_rng = {
|
||
|
|
.name = "nomadik",
|
||
|
|
.read = nmk_rng_read,
|
||
|
|
};
|
||
|
|
|
||
|
|
static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
|
||
|
|
{
|
||
|
|
void __iomem *base;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
rng_clk = devm_clk_get(&dev->dev, NULL);
|
||
|
|
if (IS_ERR(rng_clk)) {
|
||
|
|
dev_err(&dev->dev, "could not get rng clock\n");
|
||
|
|
ret = PTR_ERR(rng_clk);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
clk_prepare_enable(rng_clk);
|
||
|
|
|
||
|
|
ret = amba_request_regions(dev, dev->dev.init_name);
|
||
|
|
if (ret)
|
||
|
|
goto out_clk;
|
||
|
|
ret = -ENOMEM;
|
||
|
|
base = devm_ioremap(&dev->dev, dev->res.start,
|
||
|
|
resource_size(&dev->res));
|
||
|
|
if (!base)
|
||
|
|
goto out_release;
|
||
|
|
nmk_rng.priv = (unsigned long)base;
|
||
|
|
ret = hwrng_register(&nmk_rng);
|
||
|
|
if (ret)
|
||
|
|
goto out_release;
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
out_release:
|
||
|
|
amba_release_regions(dev);
|
||
|
|
out_clk:
|
||
|
|
clk_disable(rng_clk);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int nmk_rng_remove(struct amba_device *dev)
|
||
|
|
{
|
||
|
|
hwrng_unregister(&nmk_rng);
|
||
|
|
amba_release_regions(dev);
|
||
|
|
clk_disable(rng_clk);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct amba_id nmk_rng_ids[] = {
|
||
|
|
{
|
||
|
|
.id = 0x000805e1,
|
||
|
|
.mask = 0x000fffff, /* top bits are rev and cfg: accept all */
|
||
|
|
},
|
||
|
|
{0, 0},
|
||
|
|
};
|
||
|
|
|
||
|
|
MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
|
||
|
|
|
||
|
|
static struct amba_driver nmk_rng_driver = {
|
||
|
|
.drv = {
|
||
|
|
.owner = THIS_MODULE,
|
||
|
|
.name = "rng",
|
||
|
|
},
|
||
|
|
.probe = nmk_rng_probe,
|
||
|
|
.remove = nmk_rng_remove,
|
||
|
|
.id_table = nmk_rng_ids,
|
||
|
|
};
|
||
|
|
|
||
|
|
module_amba_driver(nmk_rng_driver);
|
||
|
|
|
||
|
|
MODULE_LICENSE("GPL");
|