drivers/nvmem/sunxi_sid.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Allwinner sunXi SoCs Security ID support.
   4  *
   5  * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
   6  * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/io.h>
  11 #include <linux/iopoll.h>
  12 #include <linux/module.h>
  13 #include <linux/nvmem-provider.h>
  14 #include <linux/of.h>
  15 #include <linux/of_device.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/slab.h>
  18 #include <linux/random.h>
  19
  20 /* Registers and special values for doing register-based SID readout on H3 */
  21 #define SUN8I_SID_PRCTL         0x40
  22 #define SUN8I_SID_RDKEY         0x60
  23
  24 #define SUN8I_SID_OFFSET_MASK   0x1FF
  25 #define SUN8I_SID_OFFSET_SHIFT  16
  26 #define SUN8I_SID_OP_LOCK       (0xAC << 8)
  27 #define SUN8I_SID_READ          BIT(1)
  28
  29 struct sunxi_sid_cfg {
  30         u32     value_offset;
  31         u32     size;
  32         bool    need_register_readout;
  33 };
  34
  35 struct sunxi_sid {
  36         void __iomem            *base;
  37         u32                     value_offset;
  38 };
  39
  40 static int sunxi_sid_read(void *context, unsigned int offset,
  41                           void *val, size_t bytes)
  42 {
  43         struct sunxi_sid *sid = context;
  44
  45         memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes);
  46
  47         return 0;
  48 }
  49
  50 static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
  51                                       const unsigned int offset,
  52                                       u32 *out)
  53 {
  54         u32 reg_val;
  55         int ret;
  56
  57         /* Set word, lock access, and set read command */
  58         reg_val = (offset & SUN8I_SID_OFFSET_MASK)
  59                   << SUN8I_SID_OFFSET_SHIFT;
  60         reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
  61         writel(reg_val, sid->base + SUN8I_SID_PRCTL);
  62
  63         ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
  64                                  !(reg_val & SUN8I_SID_READ), 100, 250000);
  65         if (ret)
  66                 return ret;
  67
  68         if (out)
  69                 *out = readl(sid->base + SUN8I_SID_RDKEY);
  70
  71         writel(0, sid->base + SUN8I_SID_PRCTL);
  72
  73         return 0;
  74 }
  75
  76 /*
  77  * On Allwinner H3, the value on the 0x200 offset of the SID controller seems
  78  * to be not reliable at all.
  79  * Read by the registers instead.
  80  */
  81 static int sun8i_sid_read_by_reg(void *context, unsigned int offset,
  82                                  void *val, size_t bytes)
  83 {
  84         struct sunxi_sid *sid = context;
  85         u32 word;
  86         int ret;
  87
  88         /* .stride = 4 so offset is guaranteed to be aligned */
  89         while (bytes >= 4) {
  90                 ret = sun8i_sid_register_readout(sid, offset, val);
  91                 if (ret)
  92                         return ret;
  93
  94                 val += 4;
  95                 offset += 4;
  96                 bytes -= 4;
  97         }
  98
  99         if (!bytes)
 100                 return 0;
 101
 102         /* Handle any trailing bytes */
 103         ret = sun8i_sid_register_readout(sid, offset, &word);
 104         if (ret)
 105                 return ret;
 106
 107         memcpy(val, &word, bytes);
 108
 109         return 0;
 110 }
 111
 112 static int sunxi_sid_probe(struct platform_device *pdev)
 113 {
 114         struct device *dev = &pdev->dev;
 115         struct resource *res;
 116         struct nvmem_config *nvmem_cfg;
 117         struct nvmem_device *nvmem;
 118         struct sunxi_sid *sid;
 119         int size;
 120         char *randomness;
 121         const struct sunxi_sid_cfg *cfg;
 122
 123         sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
 124         if (!sid)
 125                 return -ENOMEM;
 126
 127         cfg = of_device_get_match_data(dev);
 128         if (!cfg)
 129                 return -EINVAL;
 130         sid->value_offset = cfg->value_offset;
 131
 132         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 133         sid->base = devm_ioremap_resource(dev, res);
 134         if (IS_ERR(sid->base))
 135                 return PTR_ERR(sid->base);
 136
 137         size = cfg->size;
 138
 139         nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
 140         if (!nvmem_cfg)
 141                 return -ENOMEM;
 142
 143         nvmem_cfg->dev = dev;
 144         nvmem_cfg->name = "sunxi-sid";
 145         nvmem_cfg->read_only = true;
 146         nvmem_cfg->size = cfg->size;
 147         nvmem_cfg->word_size = 1;
 148         nvmem_cfg->stride = 4;
 149         nvmem_cfg->priv = sid;
 150         if (cfg->need_register_readout)
 151                 nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
 152         else
 153                 nvmem_cfg->reg_read = sunxi_sid_read;
 154
 155         nvmem = devm_nvmem_register(dev, nvmem_cfg);
 156         if (IS_ERR(nvmem))
 157                 return PTR_ERR(nvmem);
 158
 159         randomness = kzalloc(size, GFP_KERNEL);
 160         if (!randomness)
 161                 return -ENOMEM;
 162
 163         nvmem_cfg->reg_read(sid, 0, randomness, size);
 164         add_device_randomness(randomness, size);
 165         kfree(randomness);
 166
 167         platform_set_drvdata(pdev, nvmem);
 168
 169         return 0;
 170 }
 171
 172 static const struct sunxi_sid_cfg sun4i_a10_cfg = {
 173         .size = 0x10,
 174 };
 175
 176 static const struct sunxi_sid_cfg sun7i_a20_cfg = {
 177         .size = 0x200,
 178 };
 179
 180 static const struct sunxi_sid_cfg sun8i_h3_cfg = {
 181         .value_offset = 0x200,
 182         .size = 0x100,
 183         .need_register_readout = true,
 184 };
 185
 186 static const struct sunxi_sid_cfg sun50i_a64_cfg = {
 187         .value_offset = 0x200,
 188         .size = 0x100,
 189         .need_register_readout = true,
 190 };
 191
 192 static const struct sunxi_sid_cfg sun50i_h6_cfg = {
 193         .value_offset = 0x200,
 194         .size = 0x200,
 195 };
 196
 197 static const struct of_device_id sunxi_sid_of_match[] = {
 198         { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
 199         { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
 200         { .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
 201         { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
 202         { .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
 203         { .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
 204         { .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
 205         {/* sentinel */},
 206 };
 207 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
 208
 209 static struct platform_driver sunxi_sid_driver = {
 210         .probe = sunxi_sid_probe,
 211         .driver = {
 212                 .name = "eeprom-sunxi-sid",
 213                 .of_match_table = sunxi_sid_of_match,
 214         },
 215 };
 216 module_platform_driver(sunxi_sid_driver);
 217
 218 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
 219 MODULE_DESCRIPTION("Allwinner sunxi security id driver");
 220 MODULE_LICENSE("GPL");