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/platform_device.h>
  18 #include <linux/nvmem-provider.h>
  19 #include <linux/slab.h>
  20 #include <linux/regmap.h>
  21 #include <linux/device.h>
  22 #include <linux/io.h>
  23 #include <linux/module.h>
  24 #include <linux/delay.h>
  25 #include <linux/of.h>
  26 #include <linux/clk.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_context {
  39         struct device *dev;
  40         void __iomem *base;
  41         struct clk *efuse_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_context *_context = context;
  56         void __iomem *base = _context->base;
  57         struct clk *clk = _context->efuse_clk;
  58         u8 *buf = val;
  59         int ret;
  60
  61         ret = clk_prepare_enable(clk);
  62         if (ret < 0) {
  63                 dev_err(_context->dev, "failed to prepare/enable efuse clk\n");
  64                 return ret;
  65         }
  66
  67         writel(EFUSE_LOAD | EFUSE_PGENB, base + REG_EFUSE_CTRL);
  68         udelay(1);
  69         while (val_size) {
  70                 writel(readl(base + REG_EFUSE_CTRL) &
  71                              (~(EFUSE_A_MASK << EFUSE_A_SHIFT)),
  72                              base + REG_EFUSE_CTRL);
  73                 writel(readl(base + REG_EFUSE_CTRL) |
  74                              ((offset & EFUSE_A_MASK) << EFUSE_A_SHIFT),
  75                              base + REG_EFUSE_CTRL);
  76                 udelay(1);
  77                 writel(readl(base + REG_EFUSE_CTRL) |
  78                              EFUSE_STROBE, base + REG_EFUSE_CTRL);
  79                 udelay(1);
  80                 *buf++ = readb(base + REG_EFUSE_DOUT);
  81                 writel(readl(base + REG_EFUSE_CTRL) &
  82                      (~EFUSE_STROBE), base + REG_EFUSE_CTRL);
  83                 udelay(1);
  84
  85                 val_size -= 1;
  86                 offset += 1;
  87         }
  88
  89         /* Switch to standby mode */
  90         writel(EFUSE_PGENB | EFUSE_CSB, base + REG_EFUSE_CTRL);
  91
  92         clk_disable_unprepare(clk);
  93
  94         return 0;
  95 }
  96
  97 static struct regmap_bus rockchip_efuse_bus = {
  98         .read = rockchip_efuse_read,
  99         .write = rockchip_efuse_write,
 100         .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
 101         .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
 102 };
 103
 104 static struct regmap_config rockchip_efuse_regmap_config = {
 105         .reg_bits = 32,
 106         .reg_stride = 1,
 107         .val_bits = 8,
 108 };
 109
 110 static struct nvmem_config econfig = {
 111         .name = "rockchip-efuse",
 112         .owner = THIS_MODULE,
 113         .read_only = true,
 114 };
 115
 116 static const struct of_device_id rockchip_efuse_match[] = {
 117         { .compatible = "rockchip,rockchip-efuse",},
 118         { /* sentinel */},
 119 };
 120 MODULE_DEVICE_TABLE(of, rockchip_efuse_match);
 121
 122 static int rockchip_efuse_probe(struct platform_device *pdev)
 123 {
 124         struct device *dev = &pdev->dev;
 125         struct resource *res;
 126         struct nvmem_device *nvmem;
 127         struct regmap *regmap;
 128         void __iomem *base;
 129         struct clk *clk;
 130         struct rockchip_efuse_context *context;
 131
 132         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 133         base = devm_ioremap_resource(dev, res);
 134         if (IS_ERR(base))
 135                 return PTR_ERR(base);
 136
 137         context = devm_kzalloc(dev, sizeof(struct rockchip_efuse_context),
 138                                GFP_KERNEL);
 139         if (IS_ERR(context))
 140                 return PTR_ERR(context);
 141
 142         clk = devm_clk_get(dev, "pclk_efuse");
 143         if (IS_ERR(clk))
 144                 return PTR_ERR(clk);
 145
 146         context->dev = dev;
 147         context->base = base;
 148         context->efuse_clk = clk;
 149
 150         rockchip_efuse_regmap_config.max_register = resource_size(res) - 1;
 151
 152         regmap = devm_regmap_init(dev, &rockchip_efuse_bus,
 153                                   context, &rockchip_efuse_regmap_config);
 154         if (IS_ERR(regmap)) {
 155                 dev_err(dev, "regmap init failed\n");
 156                 return PTR_ERR(regmap);
 157         }
 158         econfig.dev = dev;
 159         nvmem = nvmem_register(&econfig);
 160         if (IS_ERR(nvmem))
 161                 return PTR_ERR(nvmem);
 162
 163         platform_set_drvdata(pdev, nvmem);
 164
 165         return 0;
 166 }
 167
 168 static int rockchip_efuse_remove(struct platform_device *pdev)
 169 {
 170         struct nvmem_device *nvmem = platform_get_drvdata(pdev);
 171
 172         return nvmem_unregister(nvmem);
 173 }
 174
 175 static struct platform_driver rockchip_efuse_driver = {
 176         .probe = rockchip_efuse_probe,
 177         .remove = rockchip_efuse_remove,
 178         .driver = {
 179                 .name = "rockchip-efuse",
 180                 .of_match_table = rockchip_efuse_match,
 181         },
 182 };
 183
 184 module_platform_driver(rockchip_efuse_driver);
 185 MODULE_DESCRIPTION("rockchip_efuse driver");
 186 MODULE_LICENSE("GPL v2");