drivers/nvmem/rockchip-efuse.c

   1 /*
   2  * Rockchip eFuse Driver
   3  *
   4  * Copyright (c) 2015 Rockchip Electronics Co. Ltd.
   5  * Author: Caesar Wang <wxt@rock-chips.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of version 2 of the GNU General Public License as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  14  * more details.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/delay.h>
  19 #include <linux/device.h>
  20 #include <linux/io.h>
  21 #include <linux/module.h>
  22 #include <linux/nvmem-provider.h>
  23 #include <linux/slab.h>
  24 #include <linux/of.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/regmap.h>
  27
  28 #define EFUSE_A_SHIFT                   6
  29 #define EFUSE_A_MASK                    0x3ff
  30 #define EFUSE_PGENB                     BIT(3)
  31 #define EFUSE_LOAD                      BIT(2)
  32 #define EFUSE_STROBE                    BIT(1)
  33 #define EFUSE_CSB                       BIT(0)
  34
  35 #define REG_EFUSE_CTRL                  0x0000
  36 #define REG_EFUSE_DOUT                  0x0004
  37
  38 struct rockchip_efuse_chip {
  39         struct device *dev;
  40         void __iomem *base;
  41         struct clk *clk;
  42 };
  43
  44 static int rockchip_efuse_write(void *context, const void *data, size_t count)
  45 {
  46         /* Nothing TBD, Read-Only */
  47         return 0;
  48 }
  49
  50 static int rockchip_efuse_read(void *context,
  51                                const void *reg, size_t reg_size,
  52                                void *val, size_t val_size)
  53 {
  54         unsigned int offset = *(u32 *)reg;
  55         struct rockchip_efuse_chip *efuse = context;
  56         u8 *buf = val;
  57         int ret;
  58
  59         ret = clk_prepare_enable(efuse->clk);
  60         if (ret < 0) {
  61                 dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
  62                 return ret;
  63         }
  64
  65         writel(EFUSE_LOAD | EFUSE_PGENB, efuse->base + REG_EFUSE_CTRL);
  66         udelay(1);
  67         while (val_size) {
  68                 writel(readl(efuse->base + REG_EFUSE_CTRL) &
  69                              (~(EFUSE_A_MASK << EFUSE_A_SHIFT)),
  70                              efuse->base + REG_EFUSE_CTRL);
  71                 writel(readl(efuse->base + REG_EFUSE_CTRL) |
  72                              ((offset & EFUSE_A_MASK) << EFUSE_A_SHIFT),
  73                              efuse->base + REG_EFUSE_CTRL);
  74                 udelay(1);
  75                 writel(readl(efuse->base + REG_EFUSE_CTRL) |
  76                              EFUSE_STROBE, efuse->base + REG_EFUSE_CTRL);
  77                 udelay(1);
  78                 *buf++ = readb(efuse->base + REG_EFUSE_DOUT);
  79                 writel(readl(efuse->base + REG_EFUSE_CTRL) &
  80                      (~EFUSE_STROBE), efuse->base + REG_EFUSE_CTRL);
  81                 udelay(1);
  82
  83                 val_size -= 1;
  84                 offset += 1;
  85         }
  86
  87         /* Switch to standby mode */
  88         writel(EFUSE_PGENB | EFUSE_CSB, efuse->base + REG_EFUSE_CTRL);
  89
  90         clk_disable_unprepare(efuse->clk);
  91
  92         return 0;
  93 }
  94
  95 static struct regmap_bus rockchip_efuse_bus = {
  96         .read = rockchip_efuse_read,
  97         .write = rockchip_efuse_write,
  98         .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
  99         .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
 100 };
 101
 102 static struct regmap_config rockchip_efuse_regmap_config = {
 103         .reg_bits = 32,
 104         .reg_stride = 1,
 105         .val_bits = 8,
 106 };
 107
 108 static struct nvmem_config econfig = {
 109         .name = "rockchip-efuse",
 110         .owner = THIS_MODULE,
 111         .read_only = true,
 112 };
 113
 114 static const struct of_device_id rockchip_efuse_match[] = {
 115         { .compatible = "rockchip,rockchip-efuse", },
 116         { /* sentinel */},
 117 };
 118 MODULE_DEVICE_TABLE(of, rockchip_efuse_match);
 119
 120 static int rockchip_efuse_probe(struct platform_device *pdev)
 121 {
 122         struct resource *res;
 123         struct nvmem_device *nvmem;
 124         struct regmap *regmap;
 125         struct rockchip_efuse_chip *efuse;
 126
 127         efuse = devm_kzalloc(&pdev->dev, sizeof(struct rockchip_efuse_chip),
 128                              GFP_KERNEL);
 129         if (!efuse)
 130                 return -ENOMEM;
 131
 132         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 133         efuse->base = devm_ioremap_resource(&pdev->dev, res);
 134         if (IS_ERR(efuse->base))
 135                 return PTR_ERR(efuse->base);
 136
 137         efuse->clk = devm_clk_get(&pdev->dev, "pclk_efuse");
 138         if (IS_ERR(efuse->clk))
 139                 return PTR_ERR(efuse->clk);
 140
 141         efuse->dev = &pdev->dev;
 142
 143         rockchip_efuse_regmap_config.max_register = resource_size(res) - 1;
 144
 145         regmap = devm_regmap_init(efuse->dev, &rockchip_efuse_bus,
 146                                   efuse, &rockchip_efuse_regmap_config);
 147         if (IS_ERR(regmap)) {
 148                 dev_err(efuse->dev, "regmap init failed\n");
 149                 return PTR_ERR(regmap);
 150         }
 151
 152         econfig.dev = efuse->dev;
 153         nvmem = nvmem_register(&econfig);
 154         if (IS_ERR(nvmem))
 155                 return PTR_ERR(nvmem);
 156
 157         platform_set_drvdata(pdev, nvmem);
 158
 159         return 0;
 160 }
 161
 162 static int rockchip_efuse_remove(struct platform_device *pdev)
 163 {
 164         struct nvmem_device *nvmem = platform_get_drvdata(pdev);
 165
 166         return nvmem_unregister(nvmem);
 167 }
 168
 169 static struct platform_driver rockchip_efuse_driver = {
 170         .probe = rockchip_efuse_probe,
 171         .remove = rockchip_efuse_remove,
 172         .driver = {
 173                 .name = "rockchip-efuse",
 174                 .of_match_table = rockchip_efuse_match,
 175         },
 176 };
 177
 178 module_platform_driver(rockchip_efuse_driver);
 179 MODULE_DESCRIPTION("rockchip_efuse driver");
 180 MODULE_LICENSE("GPL v2");