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 .owner = THIS_MODULE, 44 }; 45 46 struct sunxi_sid_cfg { 47 u32 value_offset; 48 u32 size; 49 bool need_register_readout; 50 }; 51 52 struct sunxi_sid { 53 void __iomem *base; 54 u32 value_offset; 55 }; 56 57 /* We read the entire key, due to a 32 bit read alignment requirement. Since we 58 * want to return the requested byte, this results in somewhat slower code and 59 * uses 4 times more reads as needed but keeps code simpler. Since the SID is 60 * only very rarely probed, this is not really an issue. 61 */ 62 static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid, 63 const unsigned int offset) 64 { 65 u32 sid_key; 66 67 sid_key = ioread32be(sid->base + round_down(offset, 4)); 68 sid_key >>= (offset % 4) * 8; 69 70 return sid_key; /* Only return the last byte */ 71 } 72 73 static int sunxi_sid_read(void *context, unsigned int offset, 74 void *val, size_t bytes) 75 { 76 struct sunxi_sid *sid = context; 77 u8 *buf = val; 78 79 /* Offset the read operation to the real position of SID */ 80 offset += sid->value_offset; 81 82 while (bytes--) 83 *buf++ = sunxi_sid_read_byte(sid, offset++); 84 85 return 0; 86 } 87 88 static int sun8i_sid_register_readout(const struct sunxi_sid *sid, 89 const unsigned int word) 90 { 91 u32 reg_val; 92 int ret; 93 94 /* Set word, lock access, and set read command */ 95 reg_val = (word & SUN8I_SID_OFFSET_MASK) 96 << SUN8I_SID_OFFSET_SHIFT; 97 reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ; 98 writel(reg_val, sid->base + SUN8I_SID_PRCTL); 99 100 ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val, 101 !(reg_val & SUN8I_SID_READ), 100, 250000); 102 if (ret) 103 return ret; 104 105 writel(0, sid->base + SUN8I_SID_PRCTL); 106 return 0; 107 } 108 109 static int sunxi_sid_probe(struct platform_device *pdev) 110 { 111 struct device *dev = &pdev->dev; 112 struct resource *res; 113 struct nvmem_device *nvmem; 114 struct sunxi_sid *sid; 115 int ret, i, size; 116 char *randomness; 117 const struct sunxi_sid_cfg *cfg; 118 119 sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL); 120 if (!sid) 121 return -ENOMEM; 122 123 cfg = of_device_get_match_data(dev); 124 if (!cfg) 125 return -EINVAL; 126 sid->value_offset = cfg->value_offset; 127 128 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 129 sid->base = devm_ioremap_resource(dev, res); 130 if (IS_ERR(sid->base)) 131 return PTR_ERR(sid->base); 132 133 size = cfg->size; 134 135 if (cfg->need_register_readout) { 136 /* 137 * H3's SID controller have a bug that the value at 0x200 138 * offset is not the correct value when the hardware is reseted. 139 * However, after doing a register-based read operation, the 140 * value become right. 141 * Do a full read operation here, but ignore its value 142 * (as it's more fast to read by direct MMIO value than 143 * with registers) 144 */ 145 for (i = 0; i < (size >> 2); i++) { 146 ret = sun8i_sid_register_readout(sid, i); 147 if (ret) 148 return ret; 149 } 150 } 151 152 econfig.size = size; 153 econfig.dev = dev; 154 econfig.reg_read = sunxi_sid_read; 155 econfig.priv = sid; 156 nvmem = nvmem_register(&econfig); 157 if (IS_ERR(nvmem)) 158 return PTR_ERR(nvmem); 159 160 randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL); 161 if (!randomness) { 162 ret = -EINVAL; 163 goto err_unreg_nvmem; 164 } 165 166 for (i = 0; i < size; i++) 167 randomness[i] = sunxi_sid_read_byte(sid, i); 168 169 add_device_randomness(randomness, size); 170 kfree(randomness); 171 172 platform_set_drvdata(pdev, nvmem); 173 174 return 0; 175 176 err_unreg_nvmem: 177 nvmem_unregister(nvmem); 178 return ret; 179 } 180 181 static int sunxi_sid_remove(struct platform_device *pdev) 182 { 183 struct nvmem_device *nvmem = platform_get_drvdata(pdev); 184 185 return nvmem_unregister(nvmem); 186 } 187 188 static const struct sunxi_sid_cfg sun4i_a10_cfg = { 189 .size = 0x10, 190 }; 191 192 static const struct sunxi_sid_cfg sun7i_a20_cfg = { 193 .size = 0x200, 194 }; 195 196 static const struct sunxi_sid_cfg sun8i_h3_cfg = { 197 .value_offset = 0x200, 198 .size = 0x100, 199 .need_register_readout = true, 200 }; 201 202 static const struct of_device_id sunxi_sid_of_match[] = { 203 { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg }, 204 { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg }, 205 { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg }, 206 {/* sentinel */}, 207 }; 208 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match); 209 210 static struct platform_driver sunxi_sid_driver = { 211 .probe = sunxi_sid_probe, 212 .remove = sunxi_sid_remove, 213 .driver = { 214 .name = "eeprom-sunxi-sid", 215 .of_match_table = sunxi_sid_of_match, 216 }, 217 }; 218 module_platform_driver(sunxi_sid_driver); 219 220 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>"); 221 MODULE_DESCRIPTION("Allwinner sunxi security id driver"); 222 MODULE_LICENSE("GPL"); 223