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/platform_device.h>
  16 #include <linux/slab.h>
  17 #include <linux/random.h>
  18
  19 /* Registers and special values for doing register-based SID readout on H3 */
  20 #define SUN8I_SID_PRCTL         0x40
  21 #define SUN8I_SID_RDKEY         0x60
  22
  23 #define SUN8I_SID_OFFSET_MASK   0x1FF
  24 #define SUN8I_SID_OFFSET_SHIFT  16
  25 #define SUN8I_SID_OP_LOCK       (0xAC << 8)
  26 #define SUN8I_SID_READ          BIT(1)
  27
  28 struct sunxi_sid_cfg {
  29         u32     value_offset;
  30         u32     size;
  31         bool    need_register_readout;
  32 };
  33
  34 struct sunxi_sid {
  35         void __iomem            *base;
  36         u32                     value_offset;
  37 };
  38
  39 static int sunxi_sid_read(void *context, unsigned int offset,
  40                           void *val, size_t bytes)
  41 {
  42         struct sunxi_sid *sid = context;
  43         u32 word;
  44
  45         /* .stride = 4 so offset is guaranteed to be aligned */
  46         __ioread32_copy(val, sid->base + sid->value_offset + offset, bytes / 4);
  47
  48         val += round_down(bytes, 4);
  49         offset += round_down(bytes, 4);
  50         bytes = bytes % 4;
  51
  52         if (!bytes)
  53                 return 0;
  54
  55         /* Handle any trailing bytes */
  56         word = readl_relaxed(sid->base + sid->value_offset + offset);
  57         memcpy(val, &word, bytes);
  58
  59         return 0;
  60 }
  61
  62 static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
  63                                       const unsigned int offset,
  64                                       u32 *out)
  65 {
  66         u32 reg_val;
  67         int ret;
  68
  69         /* Set word, lock access, and set read command */
  70         reg_val = (offset & SUN8I_SID_OFFSET_MASK)
  71                   << SUN8I_SID_OFFSET_SHIFT;
  72         reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
  73         writel(reg_val, sid->base + SUN8I_SID_PRCTL);
  74
  75         ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
  76                                  !(reg_val & SUN8I_SID_READ), 100, 250000);
  77         if (ret)
  78                 return ret;
  79
  80         if (out)
  81                 *out = readl(sid->base + SUN8I_SID_RDKEY);
  82
  83         writel(0, sid->base + SUN8I_SID_PRCTL);
  84
  85         return 0;
  86 }
  87
  88 /*
  89  * On Allwinner H3, the value on the 0x200 offset of the SID controller seems
  90  * to be not reliable at all.
  91  * Read by the registers instead.
  92  */
  93 static int sun8i_sid_read_by_reg(void *context, unsigned int offset,
  94                                  void *val, size_t bytes)
  95 {
  96         struct sunxi_sid *sid = context;
  97         u32 word;
  98         int ret;
  99
 100         /* .stride = 4 so offset is guaranteed to be aligned */
 101         while (bytes >= 4) {
 102                 ret = sun8i_sid_register_readout(sid, offset, val);
 103                 if (ret)
 104                         return ret;
 105
 106                 val += 4;
 107                 offset += 4;
 108                 bytes -= 4;
 109         }
 110
 111         if (!bytes)
 112                 return 0;
 113
 114         /* Handle any trailing bytes */
 115         ret = sun8i_sid_register_readout(sid, offset, &word);
 116         if (ret)
 117                 return ret;
 118
 119         memcpy(val, &word, bytes);
 120
 121         return 0;
 122 }
 123
 124 static int sunxi_sid_probe(struct platform_device *pdev)
 125 {
 126         struct device *dev = &pdev->dev;
 127         struct nvmem_config *nvmem_cfg;
 128         struct nvmem_device *nvmem;
 129         struct sunxi_sid *sid;
 130         int size;
 131         char *randomness;
 132         const struct sunxi_sid_cfg *cfg;
 133
 134         sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
 135         if (!sid)
 136                 return -ENOMEM;
 137
 138         cfg = of_device_get_match_data(dev);
 139         if (!cfg)
 140                 return -EINVAL;
 141         sid->value_offset = cfg->value_offset;
 142
 143         sid->base = devm_platform_ioremap_resource(pdev, 0);
 144         if (IS_ERR(sid->base))
 145                 return PTR_ERR(sid->base);
 146
 147         size = cfg->size;
 148
 149         nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
 150         if (!nvmem_cfg)
 151                 return -ENOMEM;
 152
 153         nvmem_cfg->dev = dev;
 154         nvmem_cfg->name = "sunxi-sid";
 155         nvmem_cfg->type = NVMEM_TYPE_OTP;
 156         nvmem_cfg->add_legacy_fixed_of_cells = true;
 157         nvmem_cfg->read_only = true;
 158         nvmem_cfg->size = cfg->size;
 159         nvmem_cfg->word_size = 1;
 160         nvmem_cfg->stride = 4;
 161         nvmem_cfg->priv = sid;
 162         if (cfg->need_register_readout)
 163                 nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
 164         else
 165                 nvmem_cfg->reg_read = sunxi_sid_read;
 166
 167         nvmem = devm_nvmem_register(dev, nvmem_cfg);
 168         if (IS_ERR(nvmem))
 169                 return PTR_ERR(nvmem);
 170
 171         randomness = kzalloc(size, GFP_KERNEL);
 172         if (!randomness)
 173                 return -ENOMEM;
 174
 175         nvmem_cfg->reg_read(sid, 0, randomness, size);
 176         add_device_randomness(randomness, size);
 177         kfree(randomness);
 178
 179         platform_set_drvdata(pdev, nvmem);
 180
 181         return 0;
 182 }
 183
 184 static const struct sunxi_sid_cfg sun4i_a10_cfg = {
 185         .size = 0x10,
 186 };
 187
 188 static const struct sunxi_sid_cfg sun7i_a20_cfg = {
 189         .size = 0x200,
 190 };
 191
 192 static const struct sunxi_sid_cfg sun8i_h3_cfg = {
 193         .value_offset = 0x200,
 194         .size = 0x100,
 195         .need_register_readout = true,
 196 };
 197
 198 static const struct sunxi_sid_cfg sun50i_a64_cfg = {
 199         .value_offset = 0x200,
 200         .size = 0x100,
 201 };
 202
 203 static const struct sunxi_sid_cfg sun50i_h6_cfg = {
 204         .value_offset = 0x200,
 205         .size = 0x200,
 206 };
 207
 208 static const struct of_device_id sunxi_sid_of_match[] = {
 209         { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
 210         { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
 211         { .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
 212         { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
 213         { .compatible = "allwinner,sun20i-d1-sid", .data = &sun50i_a64_cfg },
 214         { .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
 215         { .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
 216         { .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
 217         {/* sentinel */},
 218 };
 219 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
 220
 221 static struct platform_driver sunxi_sid_driver = {
 222         .probe = sunxi_sid_probe,
 223         .driver = {
 224                 .name = "eeprom-sunxi-sid",
 225                 .of_match_table = sunxi_sid_of_match,
 226         },
 227 };
 228 module_platform_driver(sunxi_sid_driver);
 229
 230 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
 231 MODULE_DESCRIPTION("Allwinner sunxi security id driver");
 232 MODULE_LICENSE("GPL");