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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mxs-ocotp.c (4125B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Freescale MXS On-Chip OTP driver
      4 *
      5 * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
      6 *
      7 * Based on the driver from Huang Shijie and Christoph G. Baumann
      8 */
      9#include <linux/clk.h>
     10#include <linux/delay.h>
     11#include <linux/device.h>
     12#include <linux/err.h>
     13#include <linux/io.h>
     14#include <linux/module.h>
     15#include <linux/nvmem-provider.h>
     16#include <linux/of_device.h>
     17#include <linux/platform_device.h>
     18#include <linux/slab.h>
     19#include <linux/stmp_device.h>
     20
     21/* OCOTP registers and bits */
     22
     23#define BM_OCOTP_CTRL_RD_BANK_OPEN	BIT(12)
     24#define BM_OCOTP_CTRL_ERROR		BIT(9)
     25#define BM_OCOTP_CTRL_BUSY		BIT(8)
     26
     27#define OCOTP_TIMEOUT		10000
     28#define OCOTP_DATA_OFFSET	0x20
     29
     30struct mxs_ocotp {
     31	struct clk *clk;
     32	void __iomem *base;
     33	struct nvmem_device *nvmem;
     34};
     35
     36static int mxs_ocotp_wait(struct mxs_ocotp *otp)
     37{
     38	int timeout = OCOTP_TIMEOUT;
     39	unsigned int status = 0;
     40
     41	while (timeout--) {
     42		status = readl(otp->base);
     43
     44		if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
     45			break;
     46
     47		cpu_relax();
     48	}
     49
     50	if (status & BM_OCOTP_CTRL_BUSY)
     51		return -EBUSY;
     52	else if (status & BM_OCOTP_CTRL_ERROR)
     53		return -EIO;
     54
     55	return 0;
     56}
     57
     58static int mxs_ocotp_read(void *context, unsigned int offset,
     59			  void *val, size_t bytes)
     60{
     61	struct mxs_ocotp *otp = context;
     62	u32 *buf = val;
     63	int ret;
     64
     65	ret = clk_enable(otp->clk);
     66	if (ret)
     67		return ret;
     68
     69	writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
     70
     71	ret = mxs_ocotp_wait(otp);
     72	if (ret)
     73		goto disable_clk;
     74
     75	/* open OCOTP banks for read */
     76	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
     77
     78	/* approximately wait 33 hclk cycles */
     79	udelay(1);
     80
     81	ret = mxs_ocotp_wait(otp);
     82	if (ret)
     83		goto close_banks;
     84
     85	while (bytes) {
     86		if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
     87			/* fill up non-data register */
     88			*buf++ = 0;
     89		} else {
     90			*buf++ = readl(otp->base + offset);
     91		}
     92
     93		bytes -= 4;
     94		offset += 4;
     95	}
     96
     97close_banks:
     98	/* close banks for power saving */
     99	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
    100
    101disable_clk:
    102	clk_disable(otp->clk);
    103
    104	return ret;
    105}
    106
    107static struct nvmem_config ocotp_config = {
    108	.name = "mxs-ocotp",
    109	.stride = 16,
    110	.word_size = 4,
    111	.reg_read = mxs_ocotp_read,
    112};
    113
    114struct mxs_data {
    115	int size;
    116};
    117
    118static const struct mxs_data imx23_data = {
    119	.size = 0x220,
    120};
    121
    122static const struct mxs_data imx28_data = {
    123	.size = 0x2a0,
    124};
    125
    126static const struct of_device_id mxs_ocotp_match[] = {
    127	{ .compatible = "fsl,imx23-ocotp", .data = &imx23_data },
    128	{ .compatible = "fsl,imx28-ocotp", .data = &imx28_data },
    129	{ /* sentinel */},
    130};
    131MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
    132
    133static void mxs_ocotp_action(void *data)
    134{
    135	clk_unprepare(data);
    136}
    137
    138static int mxs_ocotp_probe(struct platform_device *pdev)
    139{
    140	struct device *dev = &pdev->dev;
    141	const struct mxs_data *data;
    142	struct mxs_ocotp *otp;
    143	const struct of_device_id *match;
    144	int ret;
    145
    146	match = of_match_device(dev->driver->of_match_table, dev);
    147	if (!match || !match->data)
    148		return -EINVAL;
    149
    150	otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
    151	if (!otp)
    152		return -ENOMEM;
    153
    154	otp->base = devm_platform_ioremap_resource(pdev, 0);
    155	if (IS_ERR(otp->base))
    156		return PTR_ERR(otp->base);
    157
    158	otp->clk = devm_clk_get(&pdev->dev, NULL);
    159	if (IS_ERR(otp->clk))
    160		return PTR_ERR(otp->clk);
    161
    162	ret = clk_prepare(otp->clk);
    163	if (ret < 0) {
    164		dev_err(dev, "failed to prepare clk: %d\n", ret);
    165		return ret;
    166	}
    167
    168	ret = devm_add_action_or_reset(&pdev->dev, mxs_ocotp_action, otp->clk);
    169	if (ret)
    170		return ret;
    171
    172	data = match->data;
    173
    174	ocotp_config.size = data->size;
    175	ocotp_config.priv = otp;
    176	ocotp_config.dev = dev;
    177	otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
    178	if (IS_ERR(otp->nvmem))
    179		return PTR_ERR(otp->nvmem);
    180
    181	platform_set_drvdata(pdev, otp);
    182
    183	return 0;
    184}
    185
    186static struct platform_driver mxs_ocotp_driver = {
    187	.probe = mxs_ocotp_probe,
    188	.driver = {
    189		.name = "mxs-ocotp",
    190		.of_match_table = mxs_ocotp_match,
    191	},
    192};
    193
    194module_platform_driver(mxs_ocotp_driver);
    195MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
    196MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
    197MODULE_LICENSE("GPL v2");