cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pasemi-rng.c (2999B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2006-2007 PA Semi, Inc
      4 *
      5 * Maintained by: Olof Johansson <olof@lixom.net>
      6 *
      7 * Driver for the PWRficient onchip rng
      8 */
      9
     10#include <linux/module.h>
     11#include <linux/kernel.h>
     12#include <linux/platform_device.h>
     13#include <linux/hw_random.h>
     14#include <linux/delay.h>
     15#include <linux/of_address.h>
     16#include <linux/of_platform.h>
     17#include <linux/io.h>
     18
     19#define SDCRNG_CTL_REG			0x00
     20#define   SDCRNG_CTL_FVLD_M		0x0000f000
     21#define   SDCRNG_CTL_FVLD_S		12
     22#define   SDCRNG_CTL_KSZ		0x00000800
     23#define   SDCRNG_CTL_RSRC_CRG		0x00000010
     24#define   SDCRNG_CTL_RSRC_RRG		0x00000000
     25#define   SDCRNG_CTL_CE			0x00000004
     26#define   SDCRNG_CTL_RE			0x00000002
     27#define   SDCRNG_CTL_DR			0x00000001
     28#define   SDCRNG_CTL_SELECT_RRG_RNG	(SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
     29#define   SDCRNG_CTL_SELECT_CRG_RNG	(SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
     30#define SDCRNG_VAL_REG			0x20
     31
     32#define MODULE_NAME "pasemi_rng"
     33
     34static int pasemi_rng_data_present(struct hwrng *rng, int wait)
     35{
     36	void __iomem *rng_regs = (void __iomem *)rng->priv;
     37	int data, i;
     38
     39	for (i = 0; i < 20; i++) {
     40		data = (in_le32(rng_regs + SDCRNG_CTL_REG)
     41			& SDCRNG_CTL_FVLD_M) ? 1 : 0;
     42		if (data || !wait)
     43			break;
     44		udelay(10);
     45	}
     46	return data;
     47}
     48
     49static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
     50{
     51	void __iomem *rng_regs = (void __iomem *)rng->priv;
     52	*data = in_le32(rng_regs + SDCRNG_VAL_REG);
     53	return 4;
     54}
     55
     56static int pasemi_rng_init(struct hwrng *rng)
     57{
     58	void __iomem *rng_regs = (void __iomem *)rng->priv;
     59	u32 ctl;
     60
     61	ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
     62	out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
     63	out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
     64
     65	return 0;
     66}
     67
     68static void pasemi_rng_cleanup(struct hwrng *rng)
     69{
     70	void __iomem *rng_regs = (void __iomem *)rng->priv;
     71	u32 ctl;
     72
     73	ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
     74	out_le32(rng_regs + SDCRNG_CTL_REG,
     75		 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
     76}
     77
     78static struct hwrng pasemi_rng = {
     79	.name		= MODULE_NAME,
     80	.init		= pasemi_rng_init,
     81	.cleanup	= pasemi_rng_cleanup,
     82	.data_present	= pasemi_rng_data_present,
     83	.data_read	= pasemi_rng_data_read,
     84};
     85
     86static int rng_probe(struct platform_device *pdev)
     87{
     88	void __iomem *rng_regs;
     89
     90	rng_regs = devm_platform_ioremap_resource(pdev, 0);
     91	if (IS_ERR(rng_regs))
     92		return PTR_ERR(rng_regs);
     93
     94	pasemi_rng.priv = (unsigned long)rng_regs;
     95
     96	pr_info("Registering PA Semi RNG\n");
     97	return devm_hwrng_register(&pdev->dev, &pasemi_rng);
     98}
     99
    100static const struct of_device_id rng_match[] = {
    101	{ .compatible      = "1682m-rng", },
    102	{ .compatible      = "pasemi,pwrficient-rng", },
    103	{ },
    104};
    105MODULE_DEVICE_TABLE(of, rng_match);
    106
    107static struct platform_driver rng_driver = {
    108	.driver = {
    109		.name = "pasemi-rng",
    110		.of_match_table = rng_match,
    111	},
    112	.probe		= rng_probe,
    113};
    114
    115module_platform_driver(rng_driver);
    116
    117MODULE_LICENSE("GPL");
    118MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
    119MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");