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         u32 word;
  45
  46         /* .stride = 4 so offset is guaranteed to be aligned */
  47         __ioread32_copy(val, sid->base + sid->value_offset + offset, bytes / 4);
  48
  49         val += round_down(bytes, 4);
  50         offset += round_down(bytes, 4);
  51         bytes = bytes % 4;
  52
  53         if (!bytes)
  54                 return 0;
  55
  56         /* Handle any trailing bytes */
  57         word = readl_relaxed(sid->base + sid->value_offset + offset);
  58         memcpy(val, &word, bytes);
  59
  60         return 0;
  61 }
  62
  63 static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
  64                                       const unsigned int offset,
  65                                       u32 *out)
  66 {
  67         u32 reg_val;
  68         int ret;
  69
  70         /* Set word, lock access, and set read command */
  71         reg_val = (offset & SUN8I_SID_OFFSET_MASK)
  72                   << SUN8I_SID_OFFSET_SHIFT;
  73         reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
  74         writel(reg_val, sid->base + SUN8I_SID_PRCTL);
  75
  76         ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
  77                                  !(reg_val & SUN8I_SID_READ), 100, 250000);
  78         if (ret)
  79                 return ret;
  80
  81         if (out)
  82                 *out = readl(sid->base + SUN8I_SID_RDKEY);
  83
  84         writel(0, sid->base + SUN8I_SID_PRCTL);
  85
  86         return 0;
  87 }
  88
  89 /*
  90  * On Allwinner H3, the value on the 0x200 offset of the SID controller seems
  91  * to be not reliable at all.
  92  * Read by the registers instead.
  93  */
  94 static int sun8i_sid_read_by_reg(void *context, unsigned int offset,
  95                                  void *val, size_t bytes)
  96 {
  97         struct sunxi_sid *sid = context;
  98         u32 word;
  99         int ret;
 100
 101         /* .stride = 4 so offset is guaranteed to be aligned */
 102         while (bytes >= 4) {
 103                 ret = sun8i_sid_register_readout(sid, offset, val);
 104                 if (ret)
 105                         return ret;
 106
 107                 val += 4;
 108                 offset += 4;
 109                 bytes -= 4;
 110         }
 111
 112         if (!bytes)
 113                 return 0;
 114
 115         /* Handle any trailing bytes */
 116         ret = sun8i_sid_register_readout(sid, offset, &word);
 117         if (ret)
 118                 return ret;
 119
 120         memcpy(val, &word, bytes);
 121
 122         return 0;
 123 }
 124
 125 static int sunxi_sid_probe(struct platform_device *pdev)
 126 {
 127         struct device *dev = &pdev->dev;
 128         struct resource *res;
 129         struct nvmem_config *nvmem_cfg;
 130         struct nvmem_device *nvmem;
 131         struct sunxi_sid *sid;
 132         int size;
 133         char *randomness;
 134         const struct sunxi_sid_cfg *cfg;
 135
 136         sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
 137         if (!sid)
 138                 return -ENOMEM;
 139
 140         cfg = of_device_get_match_data(dev);
 141         if (!cfg)
 142                 return -EINVAL;
 143         sid->value_offset = cfg->value_offset;
 144
 145         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 146         sid->base = devm_ioremap_resource(dev, res);
 147         if (IS_ERR(sid->base))
 148                 return PTR_ERR(sid->base);
 149
 150         size = cfg->size;
 151
 152         nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
 153         if (!nvmem_cfg)
 154                 return -ENOMEM;
 155
 156         nvmem_cfg->dev = dev;
 157         nvmem_cfg->name = "sunxi-sid";
 158         nvmem_cfg->type = NVMEM_TYPE_OTP;
 159         nvmem_cfg->read_only = true;
 160         nvmem_cfg->size = cfg->size;
 161         nvmem_cfg->word_size = 1;
 162         nvmem_cfg->stride = 4;
 163         nvmem_cfg->priv = sid;
 164         if (cfg->need_register_readout)
 165                 nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
 166         else
 167                 nvmem_cfg->reg_read = sunxi_sid_read;
 168
 169         nvmem = devm_nvmem_register(dev, nvmem_cfg);
 170         if (IS_ERR(nvmem))
 171                 return PTR_ERR(nvmem);
 172
 173         randomness = kzalloc(size, GFP_KERNEL);
 174         if (!randomness)
 175                 return -ENOMEM;
 176
 177         nvmem_cfg->reg_read(sid, 0, randomness, size);
 178         add_device_randomness(randomness, size);
 179         kfree(randomness);
 180
 181         platform_set_drvdata(pdev, nvmem);
 182
 183         return 0;
 184 }
 185
 186 static const struct sunxi_sid_cfg sun4i_a10_cfg = {
 187         .size = 0x10,
 188 };
 189
 190 static const struct sunxi_sid_cfg sun7i_a20_cfg = {
 191         .size = 0x200,
 192 };
 193
 194 static const struct sunxi_sid_cfg sun8i_h3_cfg = {
 195         .value_offset = 0x200,
 196         .size = 0x100,
 197         .need_register_readout = true,
 198 };
 199
 200 static const struct sunxi_sid_cfg sun50i_a64_cfg = {
 201         .value_offset = 0x200,
 202         .size = 0x100,
 203 };
 204
 205 static const struct sunxi_sid_cfg sun50i_h6_cfg = {
 206         .value_offset = 0x200,
 207         .size = 0x200,
 208 };
 209
 210 static const struct of_device_id sunxi_sid_of_match[] = {
 211         { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
 212         { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
 213         { .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
 214         { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
 215         { .compatible = "allwinner,sun20i-d1-sid", .data = &sun50i_a64_cfg },
 216         { .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
 217         { .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
 218         { .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
 219         {/* sentinel */},
 220 };
 221 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
 222
 223 static struct platform_driver sunxi_sid_driver = {
 224         .probe = sunxi_sid_probe,
 225         .driver = {
 226                 .name = "eeprom-sunxi-sid",
 227                 .of_match_table = sunxi_sid_of_match,
 228         },
 229 };
 230 module_platform_driver(sunxi_sid_driver);
 231
 232 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
 233 MODULE_DESCRIPTION("Allwinner sunxi security id driver");
 234 MODULE_LICENSE("GPL");