drivers/nvmem/mxs-ocotp.c

   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
  30 struct mxs_ocotp {
  31         struct clk *clk;
  32         void __iomem *base;
  33         struct nvmem_device *nvmem;
  34 };
  35
  36 static 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
  58 static 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
  97 close_banks:
  98         /* close banks for power saving */
  99         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
 100
 101 disable_clk:
 102         clk_disable(otp->clk);
 103
 104         return ret;
 105 }
 106
 107 static struct nvmem_config ocotp_config = {
 108         .name = "mxs-ocotp",
 109         .stride = 16,
 110         .word_size = 4,
 111         .reg_read = mxs_ocotp_read,
 112 };
 113
 114 struct mxs_data {
 115         int size;
 116 };
 117
 118 static const struct mxs_data imx23_data = {
 119         .size = 0x220,
 120 };
 121
 122 static const struct mxs_data imx28_data = {
 123         .size = 0x2a0,
 124 };
 125
 126 static 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 };
 131 MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
 132
 133 static void mxs_ocotp_action(void *data)
 134 {
 135         clk_unprepare(data);
 136 }
 137
 138 static 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
 186 static 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
 194 module_platform_driver(mxs_ocotp_driver);
 195 MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
 196 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
 197 MODULE_LICENSE("GPL v2");