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.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           10000
  29 #define OCOTP_DATA_OFFSET       0x20
  30
  31 struct mxs_ocotp {
  32         struct clk *clk;
  33         void __iomem *base;
  34         struct nvmem_device *nvmem;
  35 };
  36
  37 static 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
  59 static 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
  98 close_banks:
  99         /* close banks for power saving */
 100         writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
 101
 102 disable_clk:
 103         clk_disable(otp->clk);
 104
 105         return ret;
 106 }
 107
 108 static struct nvmem_config ocotp_config = {
 109         .name = "mxs-ocotp",
 110         .stride = 16,
 111         .word_size = 4,
 112         .reg_read = mxs_ocotp_read,
 113 };
 114
 115 struct mxs_data {
 116         int size;
 117 };
 118
 119 static const struct mxs_data imx23_data = {
 120         .size = 0x220,
 121 };
 122
 123 static const struct mxs_data imx28_data = {
 124         .size = 0x2a0,
 125 };
 126
 127 static 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 };
 132 MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
 133
 134 static void mxs_ocotp_action(void *data)
 135 {
 136         clk_unprepare(data);
 137 }
 138
 139 static 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
 184 static 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
 192 module_platform_driver(mxs_ocotp_driver);
 193 MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
 194 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
 195 MODULE_LICENSE("GPL v2");