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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Freescale MXS On-Chip OTP driver4 *5 * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>6 *7 * Based on the driver from Huang Shijie and Christoph G. Baumann8 */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.h>17#include <linux/platform_device.h>18#include <linux/property.h>19#include <linux/slab.h>20#include <linux/stmp_device.h>21 22/* OCOTP registers and bits */23 24#define BM_OCOTP_CTRL_RD_BANK_OPEN BIT(12)25#define BM_OCOTP_CTRL_ERROR BIT(9)26#define BM_OCOTP_CTRL_BUSY BIT(8)27 28#define OCOTP_TIMEOUT 1000029#define OCOTP_DATA_OFFSET 0x2030 31struct mxs_ocotp {32 struct clk *clk;33 void __iomem *base;34 struct nvmem_device *nvmem;35};36 37static int mxs_ocotp_wait(struct mxs_ocotp *otp)38{39 int timeout = OCOTP_TIMEOUT;40 unsigned int status = 0;41 42 while (timeout--) {43 status = readl(otp->base);44 45 if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))46 break;47 48 cpu_relax();49 }50 51 if (status & BM_OCOTP_CTRL_BUSY)52 return -EBUSY;53 else if (status & BM_OCOTP_CTRL_ERROR)54 return -EIO;55 56 return 0;57}58 59static int mxs_ocotp_read(void *context, unsigned int offset,60 void *val, size_t bytes)61{62 struct mxs_ocotp *otp = context;63 u32 *buf = val;64 int ret;65 66 ret = clk_enable(otp->clk);67 if (ret)68 return ret;69 70 writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);71 72 ret = mxs_ocotp_wait(otp);73 if (ret)74 goto disable_clk;75 76 /* open OCOTP banks for read */77 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);78 79 /* approximately wait 33 hclk cycles */80 udelay(1);81 82 ret = mxs_ocotp_wait(otp);83 if (ret)84 goto close_banks;85 86 while (bytes) {87 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {88 /* fill up non-data register */89 *buf++ = 0;90 } else {91 *buf++ = readl(otp->base + offset);92 }93 94 bytes -= 4;95 offset += 4;96 }97 98close_banks:99 /* close banks for power saving */100 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);101 102disable_clk:103 clk_disable(otp->clk);104 105 return ret;106}107 108static struct nvmem_config ocotp_config = {109 .name = "mxs-ocotp",110 .stride = 16,111 .word_size = 4,112 .reg_read = mxs_ocotp_read,113};114 115struct mxs_data {116 int size;117};118 119static const struct mxs_data imx23_data = {120 .size = 0x220,121};122 123static const struct mxs_data imx28_data = {124 .size = 0x2a0,125};126 127static const struct of_device_id mxs_ocotp_match[] = {128 { .compatible = "fsl,imx23-ocotp", .data = &imx23_data },129 { .compatible = "fsl,imx28-ocotp", .data = &imx28_data },130 { /* sentinel */},131};132MODULE_DEVICE_TABLE(of, mxs_ocotp_match);133 134static void mxs_ocotp_action(void *data)135{136 clk_unprepare(data);137}138 139static int mxs_ocotp_probe(struct platform_device *pdev)140{141 struct device *dev = &pdev->dev;142 const struct mxs_data *data;143 struct mxs_ocotp *otp;144 int ret;145 146 data = device_get_match_data(dev);147 if (!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 ocotp_config.size = data->size;173 ocotp_config.priv = otp;174 ocotp_config.dev = dev;175 otp->nvmem = devm_nvmem_register(dev, &ocotp_config);176 if (IS_ERR(otp->nvmem))177 return PTR_ERR(otp->nvmem);178 179 platform_set_drvdata(pdev, otp);180 181 return 0;182}183 184static struct platform_driver mxs_ocotp_driver = {185 .probe = mxs_ocotp_probe,186 .driver = {187 .name = "mxs-ocotp",188 .of_match_table = mxs_ocotp_match,189 },190};191 192module_platform_driver(mxs_ocotp_driver);193MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");194MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");195MODULE_LICENSE("GPL v2");196