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/slab.h>
  29 #include <linux/stmp_device.h>
  30
  31 /* OCOTP registers and bits */
  32
  33 #define BM_OCOTP_CTRL_RD_BANK_OPEN      BIT(12)
  34 #define BM_OCOTP_CTRL_ERROR             BIT(9)
  35 #define BM_OCOTP_CTRL_BUSY              BIT(8)
  36
  37 #define OCOTP_TIMEOUT           10000
  38 #define OCOTP_DATA_OFFSET       0x20
  39
  40 struct mxs_ocotp {
  41         struct clk *clk;
  42         void __iomem *base;
  43         struct nvmem_device *nvmem;
  44 };
  45
  46 static int mxs_ocotp_wait(struct mxs_ocotp *otp)
  47 {
  48         int timeout = OCOTP_TIMEOUT;
  49         unsigned int status = 0;
  50
  51         while (timeout--) {
  52                 status = readl(otp->base);
  53
  54                 if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
  55                         break;
  56
  57                 cpu_relax();
  58         }
  59
  60         if (status & BM_OCOTP_CTRL_BUSY)
  61                 return -EBUSY;
  62         else if (status & BM_OCOTP_CTRL_ERROR)
  63                 return -EIO;
  64
  65         return 0;
  66 }
  67
  68 static int mxs_ocotp_read(void *context, unsigned int offset,
  69                           void *val, size_t bytes)
  70 {
  71         struct mxs_ocotp *otp = context;
  72         u32 *buf = val;
  73         int ret;
  74
  75         ret = clk_enable(otp->clk);
  76         if (ret)
  77                 return ret;
  78
  79         writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
  80
  81         ret = mxs_ocotp_wait(otp);
  82         if (ret)
  83                 goto disable_clk;
  84
  85         /* open OCOTP banks for read */
  86         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
  87
  88         /* approximately wait 33 hclk cycles */
  89         udelay(1);
  90
  91         ret = mxs_ocotp_wait(otp);
  92         if (ret)
  93                 goto close_banks;
  94
  95         while (bytes) {
  96                 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
  97                         /* fill up non-data register */
  98                         *buf++ = 0;
  99                 } else {
 100                         *buf++ = readl(otp->base + offset);
 101                 }
 102
 103                 bytes -= 4;
 104                 offset += 4;
 105         }
 106
 107 close_banks:
 108         /* close banks for power saving */
 109         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
 110
 111 disable_clk:
 112         clk_disable(otp->clk);
 113
 114         return ret;
 115 }
 116
 117 static struct nvmem_config ocotp_config = {
 118         .name = "mxs-ocotp",
 119         .stride = 16,
 120         .word_size = 4,
 121         .reg_read = mxs_ocotp_read,
 122 };
 123
 124 struct mxs_data {
 125         int size;
 126 };
 127
 128 static const struct mxs_data imx23_data = {
 129         .size = 0x220,
 130 };
 131
 132 static const struct mxs_data imx28_data = {
 133         .size = 0x2a0,
 134 };
 135
 136 static const struct of_device_id mxs_ocotp_match[] = {
 137         { .compatible = "fsl,imx23-ocotp", .data = &imx23_data },
 138         { .compatible = "fsl,imx28-ocotp", .data = &imx28_data },
 139         { /* sentinel */},
 140 };
 141 MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
 142
 143 static int mxs_ocotp_probe(struct platform_device *pdev)
 144 {
 145         struct device *dev = &pdev->dev;
 146         const struct mxs_data *data;
 147         struct mxs_ocotp *otp;
 148         struct resource *res;
 149         const struct of_device_id *match;
 150         int ret;
 151
 152         match = of_match_device(dev->driver->of_match_table, dev);
 153         if (!match || !match->data)
 154                 return -EINVAL;
 155
 156         otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
 157         if (!otp)
 158                 return -ENOMEM;
 159
 160         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 161         otp->base = devm_ioremap_resource(dev, res);
 162         if (IS_ERR(otp->base))
 163                 return PTR_ERR(otp->base);
 164
 165         otp->clk = devm_clk_get(&pdev->dev, NULL);
 166         if (IS_ERR(otp->clk))
 167                 return PTR_ERR(otp->clk);
 168
 169         ret = clk_prepare(otp->clk);
 170         if (ret < 0) {
 171                 dev_err(dev, "failed to prepare clk: %d\n", ret);
 172                 return ret;
 173         }
 174
 175         data = match->data;
 176
 177         ocotp_config.size = data->size;
 178         ocotp_config.priv = otp;
 179         ocotp_config.dev = dev;
 180         otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
 181         if (IS_ERR(otp->nvmem)) {
 182                 ret = PTR_ERR(otp->nvmem);
 183                 goto err_clk;
 184         }
 185
 186         platform_set_drvdata(pdev, otp);
 187
 188         return 0;
 189
 190 err_clk:
 191         clk_unprepare(otp->clk);
 192
 193         return ret;
 194 }
 195
 196 static int mxs_ocotp_remove(struct platform_device *pdev)
 197 {
 198         struct mxs_ocotp *otp = platform_get_drvdata(pdev);
 199
 200         clk_unprepare(otp->clk);
 201
 202         return 0;
 203 }
 204
 205 static struct platform_driver mxs_ocotp_driver = {
 206         .probe = mxs_ocotp_probe,
 207         .remove = mxs_ocotp_remove,
 208         .driver = {
 209                 .name = "mxs-ocotp",
 210                 .of_match_table = mxs_ocotp_match,
 211         },
 212 };
 213
 214 module_platform_driver(mxs_ocotp_driver);
 215 MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
 216 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
 217 MODULE_LICENSE("GPL v2");