drivers/nvmem/mxs-ocotp.c

   1 /*
   2  * Freescale MXS On-Chip OTP driver
   3  *
   4  * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
   5  *
   6  * Based on the driver from Huang Shijie and Christoph G. Baumann
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  */
  19 #include <linux/clk.h>
  20 #include <linux/delay.h>
  21 #include <linux/device.h>
  22 #include <linux/err.h>
  23 #include <linux/io.h>
  24 #include <linux/module.h>
  25 #include <linux/nvmem-provider.h>
  26 #include <linux/of_device.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/regmap.h>
  29 #include <linux/slab.h>
  30 #include <linux/stmp_device.h>
  31
  32 /* OCOTP registers and bits */
  33
  34 #define BM_OCOTP_CTRL_RD_BANK_OPEN      BIT(12)
  35 #define BM_OCOTP_CTRL_ERROR             BIT(9)
  36 #define BM_OCOTP_CTRL_BUSY              BIT(8)
  37
  38 #define OCOTP_TIMEOUT           10000
  39 #define OCOTP_DATA_OFFSET       0x20
  40
  41 struct mxs_ocotp {
  42         struct clk *clk;
  43         void __iomem *base;
  44         struct nvmem_device *nvmem;
  45 };
  46
  47 static int mxs_ocotp_wait(struct mxs_ocotp *otp)
  48 {
  49         int timeout = OCOTP_TIMEOUT;
  50         unsigned int status = 0;
  51
  52         while (timeout--) {
  53                 status = readl(otp->base);
  54
  55                 if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
  56                         break;
  57
  58                 cpu_relax();
  59         }
  60
  61         if (status & BM_OCOTP_CTRL_BUSY)
  62                 return -EBUSY;
  63         else if (status & BM_OCOTP_CTRL_ERROR)
  64                 return -EIO;
  65
  66         return 0;
  67 }
  68
  69 static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
  70                           void *val, size_t val_size)
  71 {
  72         struct mxs_ocotp *otp = context;
  73         unsigned int offset = *(u32 *)reg;
  74         u32 *buf = val;
  75         int ret;
  76
  77         ret = clk_enable(otp->clk);
  78         if (ret)
  79                 return ret;
  80
  81         writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
  82
  83         ret = mxs_ocotp_wait(otp);
  84         if (ret)
  85                 goto disable_clk;
  86
  87         /* open OCOTP banks for read */
  88         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
  89
  90         /* approximately wait 33 hclk cycles */
  91         udelay(1);
  92
  93         ret = mxs_ocotp_wait(otp);
  94         if (ret)
  95                 goto close_banks;
  96
  97         while (val_size) {
  98                 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
  99                         /* fill up non-data register */
 100                         *buf = 0;
 101                 } else {
 102                         *buf = readl(otp->base + offset);
 103                 }
 104
 105                 buf++;
 106                 val_size--;
 107                 offset += reg_size;
 108         }
 109
 110 close_banks:
 111         /* close banks for power saving */
 112         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
 113
 114 disable_clk:
 115         clk_disable(otp->clk);
 116
 117         return ret;
 118 }
 119
 120 static int mxs_ocotp_write(void *context, const void *data, size_t count)
 121 {
 122         /* We don't want to support writing */
 123         return 0;
 124 }
 125
 126 static bool mxs_ocotp_writeable_reg(struct device *dev, unsigned int reg)
 127 {
 128         return false;
 129 }
 130
 131 static struct nvmem_config ocotp_config = {
 132         .name = "mxs-ocotp",
 133         .owner = THIS_MODULE,
 134 };
 135
 136 static const struct regmap_range imx23_ranges[] = {
 137         regmap_reg_range(OCOTP_DATA_OFFSET, 0x210),
 138 };
 139
 140 static const struct regmap_access_table imx23_access = {
 141         .yes_ranges = imx23_ranges,
 142         .n_yes_ranges = ARRAY_SIZE(imx23_ranges),
 143 };
 144
 145 static const struct regmap_range imx28_ranges[] = {
 146         regmap_reg_range(OCOTP_DATA_OFFSET, 0x290),
 147 };
 148
 149 static const struct regmap_access_table imx28_access = {
 150         .yes_ranges = imx28_ranges,
 151         .n_yes_ranges = ARRAY_SIZE(imx28_ranges),
 152 };
 153
 154 static struct regmap_bus mxs_ocotp_bus = {
 155         .read = mxs_ocotp_read,
 156         .write = mxs_ocotp_write, /* make regmap_init() happy */
 157         .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
 158         .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
 159 };
 160
 161 static struct regmap_config mxs_ocotp_config = {
 162         .reg_bits = 32,
 163         .val_bits = 32,
 164         .reg_stride = 16,
 165         .writeable_reg = mxs_ocotp_writeable_reg,
 166 };
 167
 168 static const struct of_device_id mxs_ocotp_match[] = {
 169         { .compatible = "fsl,imx23-ocotp", .data = &imx23_access },
 170         { .compatible = "fsl,imx28-ocotp", .data = &imx28_access },
 171         { /* sentinel */},
 172 };
 173 MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
 174
 175 static int mxs_ocotp_probe(struct platform_device *pdev)
 176 {
 177         struct device *dev = &pdev->dev;
 178         struct mxs_ocotp *otp;
 179         struct resource *res;
 180         const struct of_device_id *match;
 181         struct regmap *regmap;
 182         const struct regmap_access_table *access;
 183         int ret;
 184
 185         match = of_match_device(dev->driver->of_match_table, dev);
 186         if (!match || !match->data)
 187                 return -EINVAL;
 188
 189         otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
 190         if (!otp)
 191                 return -ENOMEM;
 192
 193         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 194         otp->base = devm_ioremap_resource(dev, res);
 195         if (IS_ERR(otp->base))
 196                 return PTR_ERR(otp->base);
 197
 198         otp->clk = devm_clk_get(&pdev->dev, NULL);
 199         if (IS_ERR(otp->clk))
 200                 return PTR_ERR(otp->clk);
 201
 202         ret = clk_prepare(otp->clk);
 203         if (ret < 0) {
 204                 dev_err(dev, "failed to prepare clk: %d\n", ret);
 205                 return ret;
 206         }
 207
 208         access = match->data;
 209         mxs_ocotp_config.rd_table = access;
 210         mxs_ocotp_config.max_register = access->yes_ranges[0].range_max;
 211
 212         regmap = devm_regmap_init(dev, &mxs_ocotp_bus, otp, &mxs_ocotp_config);
 213         if (IS_ERR(regmap)) {
 214                 dev_err(dev, "regmap init failed\n");
 215                 ret = PTR_ERR(regmap);
 216                 goto err_clk;
 217         }
 218
 219         ocotp_config.dev = dev;
 220         otp->nvmem = nvmem_register(&ocotp_config);
 221         if (IS_ERR(otp->nvmem)) {
 222                 ret = PTR_ERR(otp->nvmem);
 223                 goto err_clk;
 224         }
 225
 226         platform_set_drvdata(pdev, otp);
 227
 228         return 0;
 229
 230 err_clk:
 231         clk_unprepare(otp->clk);
 232
 233         return ret;
 234 }
 235
 236 static int mxs_ocotp_remove(struct platform_device *pdev)
 237 {
 238         struct mxs_ocotp *otp = platform_get_drvdata(pdev);
 239
 240         clk_unprepare(otp->clk);
 241
 242         return nvmem_unregister(otp->nvmem);
 243 }
 244
 245 static struct platform_driver mxs_ocotp_driver = {
 246         .probe = mxs_ocotp_probe,
 247         .remove = mxs_ocotp_remove,
 248         .driver = {
 249                 .name = "mxs-ocotp",
 250                 .of_match_table = mxs_ocotp_match,
 251         },
 252 };
 253
 254 module_platform_driver(mxs_ocotp_driver);
 255 MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
 256 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
 257 MODULE_LICENSE("GPL v2");