1 /* 2 * Allwinner sunXi SoCs Security ID support. 3 * 4 * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl> 5 * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 */ 17 18 #include <linux/device.h> 19 #include <linux/io.h> 20 #include <linux/iopoll.h> 21 #include <linux/module.h> 22 #include <linux/nvmem-provider.h> 23 #include <linux/of.h> 24 #include <linux/of_device.h> 25 #include <linux/platform_device.h> 26 #include <linux/slab.h> 27 #include <linux/random.h> 28 29 /* Registers and special values for doing register-based SID readout on H3 */ 30 #define SUN8I_SID_PRCTL 0x40 31 #define SUN8I_SID_RDKEY 0x60 32 33 #define SUN8I_SID_OFFSET_MASK 0x1FF 34 #define SUN8I_SID_OFFSET_SHIFT 16 35 #define SUN8I_SID_OP_LOCK (0xAC << 8) 36 #define SUN8I_SID_READ BIT(1) 37 38 static struct nvmem_config econfig = { 39 .name = "sunxi-sid", 40 .read_only = true, 41 .stride = 4, 42 .word_size = 1, 43 }; 44 45 struct sunxi_sid_cfg { 46 u32 value_offset; 47 u32 size; 48 bool need_register_readout; 49 }; 50 51 struct sunxi_sid { 52 void __iomem *base; 53 u32 value_offset; 54 }; 55 56 /* We read the entire key, due to a 32 bit read alignment requirement. Since we 57 * want to return the requested byte, this results in somewhat slower code and 58 * uses 4 times more reads as needed but keeps code simpler. Since the SID is 59 * only very rarely probed, this is not really an issue. 60 */ 61 static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid, 62 const unsigned int offset) 63 { 64 u32 sid_key; 65 66 sid_key = ioread32be(sid->base + round_down(offset, 4)); 67 sid_key >>= (offset % 4) * 8; 68 69 return sid_key; /* Only return the last byte */ 70 } 71 72 static int sunxi_sid_read(void *context, unsigned int offset, 73 void *val, size_t bytes) 74 { 75 struct sunxi_sid *sid = context; 76 u8 *buf = val; 77 78 /* Offset the read operation to the real position of SID */ 79 offset += sid->value_offset; 80 81 while (bytes--) 82 *buf++ = sunxi_sid_read_byte(sid, offset++); 83 84 return 0; 85 } 86 87 static int sun8i_sid_register_readout(const struct sunxi_sid *sid, 88 const unsigned int word) 89 { 90 u32 reg_val; 91 int ret; 92 93 /* Set word, lock access, and set read command */ 94 reg_val = (word & SUN8I_SID_OFFSET_MASK) 95 << SUN8I_SID_OFFSET_SHIFT; 96 reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ; 97 writel(reg_val, sid->base + SUN8I_SID_PRCTL); 98 99 ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val, 100 !(reg_val & SUN8I_SID_READ), 100, 250000); 101 if (ret) 102 return ret; 103 104 writel(0, sid->base + SUN8I_SID_PRCTL); 105 return 0; 106 } 107 108 static int sunxi_sid_probe(struct platform_device *pdev) 109 { 110 struct device *dev = &pdev->dev; 111 struct resource *res; 112 struct nvmem_device *nvmem; 113 struct sunxi_sid *sid; 114 int ret, i, size; 115 char *randomness; 116 const struct sunxi_sid_cfg *cfg; 117 118 sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL); 119 if (!sid) 120 return -ENOMEM; 121 122 cfg = of_device_get_match_data(dev); 123 if (!cfg) 124 return -EINVAL; 125 sid->value_offset = cfg->value_offset; 126 127 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 128 sid->base = devm_ioremap_resource(dev, res); 129 if (IS_ERR(sid->base)) 130 return PTR_ERR(sid->base); 131 132 size = cfg->size; 133 134 if (cfg->need_register_readout) { 135 /* 136 * H3's SID controller have a bug that the value at 0x200 137 * offset is not the correct value when the hardware is reseted. 138 * However, after doing a register-based read operation, the 139 * value become right. 140 * Do a full read operation here, but ignore its value 141 * (as it's more fast to read by direct MMIO value than 142 * with registers) 143 */ 144 for (i = 0; i < (size >> 2); i++) { 145 ret = sun8i_sid_register_readout(sid, i); 146 if (ret) 147 return ret; 148 } 149 } 150 151 econfig.size = size; 152 econfig.dev = dev; 153 econfig.reg_read = sunxi_sid_read; 154 econfig.priv = sid; 155 nvmem = nvmem_register(&econfig); 156 if (IS_ERR(nvmem)) 157 return PTR_ERR(nvmem); 158 159 randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL); 160 if (!randomness) { 161 ret = -EINVAL; 162 goto err_unreg_nvmem; 163 } 164 165 for (i = 0; i < size; i++) 166 randomness[i] = sunxi_sid_read_byte(sid, i); 167 168 add_device_randomness(randomness, size); 169 kfree(randomness); 170 171 platform_set_drvdata(pdev, nvmem); 172 173 return 0; 174 175 err_unreg_nvmem: 176 nvmem_unregister(nvmem); 177 return ret; 178 } 179 180 static int sunxi_sid_remove(struct platform_device *pdev) 181 { 182 struct nvmem_device *nvmem = platform_get_drvdata(pdev); 183 184 return nvmem_unregister(nvmem); 185 } 186 187 static const struct sunxi_sid_cfg sun4i_a10_cfg = { 188 .size = 0x10, 189 }; 190 191 static const struct sunxi_sid_cfg sun7i_a20_cfg = { 192 .size = 0x200, 193 }; 194 195 static const struct sunxi_sid_cfg sun8i_h3_cfg = { 196 .value_offset = 0x200, 197 .size = 0x100, 198 .need_register_readout = true, 199 }; 200 201 static const struct sunxi_sid_cfg sun50i_a64_cfg = { 202 .value_offset = 0x200, 203 .size = 0x100, 204 }; 205 206 static const struct of_device_id sunxi_sid_of_match[] = { 207 { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg }, 208 { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg }, 209 { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg }, 210 { .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg }, 211 {/* sentinel */}, 212 }; 213 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match); 214 215 static struct platform_driver sunxi_sid_driver = { 216 .probe = sunxi_sid_probe, 217 .remove = sunxi_sid_remove, 218 .driver = { 219 .name = "eeprom-sunxi-sid", 220 .of_match_table = sunxi_sid_of_match, 221 }, 222 }; 223 module_platform_driver(sunxi_sid_driver); 224 225 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>"); 226 MODULE_DESCRIPTION("Allwinner sunxi security id driver"); 227 MODULE_LICENSE("GPL"); 228