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/*
* Generic PowerPC 44x RNG driver
*
* Copyright 2011 IBM Corporation
*
* 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; version 2 of the License.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <asm/io.h>
#define PPC4XX_TRNG_DEV_CTRL 0x60080
#define PPC4XX_TRNGE 0x00020000
#define PPC4XX_TRNG_CTRL 0x0008
#define PPC4XX_TRNG_CTRL_DALM 0x20
#define PPC4XX_TRNG_STAT 0x0004
#define PPC4XX_TRNG_STAT_B 0x1
#define PPC4XX_TRNG_DATA 0x0000
#define MODULE_NAME "ppc4xx_rng"
static int ppc4xx_rng_data_present(struct hwrng *rng, int wait)
{
void __iomem *rng_regs = (void __iomem *) rng->priv;
int busy, i, present = 0;
for (i = 0; i < 20; i++) {
busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B);
if (!busy || !wait) {
present = 1;
break;
}
udelay(10);
}
return present;
}
static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data)
{
void __iomem *rng_regs = (void __iomem *) rng->priv;
*data = in_le32(rng_regs + PPC4XX_TRNG_DATA);
return 4;
}
static int ppc4xx_rng_enable(int enable)
{
struct device_node *ctrl;
void __iomem *ctrl_reg;
int err = 0;
u32 val;
/* Find the main crypto device node and map it to turn the TRNG on */
ctrl = of_find_compatible_node(NULL, NULL, "amcc,ppc4xx-crypto");
if (!ctrl)
return -ENODEV;
ctrl_reg = of_iomap(ctrl, 0);
if (!ctrl_reg) {
err = -ENODEV;
goto out;
}
val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL);
if (enable)
val |= PPC4XX_TRNGE;
else
val = val & ~PPC4XX_TRNGE;
out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val);
iounmap(ctrl_reg);
out:
of_node_put(ctrl);
return err;
}
static struct hwrng ppc4xx_rng = {
.name = MODULE_NAME,
.data_present = ppc4xx_rng_data_present,
.data_read = ppc4xx_rng_data_read,
};
static int ppc4xx_rng_probe(struct platform_device *dev)
{
void __iomem *rng_regs;
int err = 0;
rng_regs = of_iomap(dev->dev.of_node, 0);
if (!rng_regs)
return -ENODEV;
err = ppc4xx_rng_enable(1);
if (err)
return err;
out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
ppc4xx_rng.priv = (unsigned long) rng_regs;
err = hwrng_register(&ppc4xx_rng);
return err;
}
static int ppc4xx_rng_remove(struct platform_device *dev)
{
void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv;
hwrng_unregister(&ppc4xx_rng);
ppc4xx_rng_enable(0);
iounmap(rng_regs);
return 0;
}
static const struct of_device_id ppc4xx_rng_match[] = {
{ .compatible = "ppc4xx-rng", },
{ .compatible = "amcc,ppc460ex-rng", },
{ .compatible = "amcc,ppc440epx-rng", },
{},
};
MODULE_DEVICE_TABLE(of, ppc4xx_rng_match);
static struct platform_driver ppc4xx_rng_driver = {
.driver = {
.name = MODULE_NAME,
.of_match_table = ppc4xx_rng_match,
},
.probe = ppc4xx_rng_probe,
.remove = ppc4xx_rng_remove,
};
module_platform_driver(ppc4xx_rng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>");
MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors");
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