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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2006-2007 PA Semi, Inc
*
* Maintained by: Olof Johansson <olof@lixom.net>
*
* Driver for the PWRficient onchip rng
*/
#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 <linux/io.h>
#define SDCRNG_CTL_REG 0x00
#define SDCRNG_CTL_FVLD_M 0x0000f000
#define SDCRNG_CTL_FVLD_S 12
#define SDCRNG_CTL_KSZ 0x00000800
#define SDCRNG_CTL_RSRC_CRG 0x00000010
#define SDCRNG_CTL_RSRC_RRG 0x00000000
#define SDCRNG_CTL_CE 0x00000004
#define SDCRNG_CTL_RE 0x00000002
#define SDCRNG_CTL_DR 0x00000001
#define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
#define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
#define SDCRNG_VAL_REG 0x20
#define MODULE_NAME "pasemi_rng"
static int pasemi_rng_data_present(struct hwrng *rng, int wait)
{
void __iomem *rng_regs = (void __iomem *)rng->priv;
int data, i;
for (i = 0; i < 20; i++) {
data = (in_le32(rng_regs + SDCRNG_CTL_REG)
& SDCRNG_CTL_FVLD_M) ? 1 : 0;
if (data || !wait)
break;
udelay(10);
}
return data;
}
static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
{
void __iomem *rng_regs = (void __iomem *)rng->priv;
*data = in_le32(rng_regs + SDCRNG_VAL_REG);
return 4;
}
static int pasemi_rng_init(struct hwrng *rng)
{
void __iomem *rng_regs = (void __iomem *)rng->priv;
u32 ctl;
ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
return 0;
}
static void pasemi_rng_cleanup(struct hwrng *rng)
{
void __iomem *rng_regs = (void __iomem *)rng->priv;
u32 ctl;
ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
out_le32(rng_regs + SDCRNG_CTL_REG,
in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
}
static struct hwrng pasemi_rng = {
.name = MODULE_NAME,
.init = pasemi_rng_init,
.cleanup = pasemi_rng_cleanup,
.data_present = pasemi_rng_data_present,
.data_read = pasemi_rng_data_read,
};
static int rng_probe(struct platform_device *pdev)
{
void __iomem *rng_regs;
rng_regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(rng_regs))
return PTR_ERR(rng_regs);
pasemi_rng.priv = (unsigned long)rng_regs;
pr_info("Registering PA Semi RNG\n");
return devm_hwrng_register(&pdev->dev, &pasemi_rng);
}
static const struct of_device_id rng_match[] = {
{ .compatible = "1682m-rng", },
{ .compatible = "pasemi,pwrficient-rng", },
{ },
};
MODULE_DEVICE_TABLE(of, rng_match);
static struct platform_driver rng_driver = {
.driver = {
.name = "pasemi-rng",
.of_match_table = rng_match,
},
.probe = rng_probe,
};
module_platform_driver(rng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
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