1 /* 2 * Copyright (C) 2015 Broadcom Corporation 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation version 2. 7 * 8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any 9 * kind, whether express or implied; without even the implied warranty 10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 /* 14 * DESCRIPTION: The Broadcom iProc RNG200 Driver 15 */ 16 17 #include <linux/hw_random.h> 18 #include <linux/init.h> 19 #include <linux/io.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/of_address.h> 23 #include <linux/of_platform.h> 24 #include <linux/platform_device.h> 25 #include <linux/delay.h> 26 27 /* Registers */ 28 #define RNG_CTRL_OFFSET 0x00 29 #define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF 30 #define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001 31 #define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000 32 33 #define RNG_SOFT_RESET_OFFSET 0x04 34 #define RNG_SOFT_RESET 0x00000001 35 36 #define RBG_SOFT_RESET_OFFSET 0x08 37 #define RBG_SOFT_RESET 0x00000001 38 39 #define RNG_INT_STATUS_OFFSET 0x18 40 #define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x80000000 41 #define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x00020000 42 #define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x00000020 43 #define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x00000001 44 45 #define RNG_FIFO_DATA_OFFSET 0x20 46 47 #define RNG_FIFO_COUNT_OFFSET 0x24 48 #define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF 49 50 struct iproc_rng200_dev { 51 struct hwrng rng; 52 void __iomem *base; 53 }; 54 55 #define to_rng_priv(rng) container_of(rng, struct iproc_rng200_dev, rng) 56 57 static void iproc_rng200_restart(void __iomem *rng_base) 58 { 59 uint32_t val; 60 61 /* Disable RBG */ 62 val = ioread32(rng_base + RNG_CTRL_OFFSET); 63 val &= ~RNG_CTRL_RNG_RBGEN_MASK; 64 val |= RNG_CTRL_RNG_RBGEN_DISABLE; 65 iowrite32(val, rng_base + RNG_CTRL_OFFSET); 66 67 /* Clear all interrupt status */ 68 iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET); 69 70 /* Reset RNG and RBG */ 71 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET); 72 val |= RBG_SOFT_RESET; 73 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET); 74 75 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET); 76 val |= RNG_SOFT_RESET; 77 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET); 78 79 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET); 80 val &= ~RNG_SOFT_RESET; 81 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET); 82 83 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET); 84 val &= ~RBG_SOFT_RESET; 85 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET); 86 87 /* Enable RBG */ 88 val = ioread32(rng_base + RNG_CTRL_OFFSET); 89 val &= ~RNG_CTRL_RNG_RBGEN_MASK; 90 val |= RNG_CTRL_RNG_RBGEN_ENABLE; 91 iowrite32(val, rng_base + RNG_CTRL_OFFSET); 92 } 93 94 static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max, 95 bool wait) 96 { 97 struct iproc_rng200_dev *priv = to_rng_priv(rng); 98 uint32_t num_remaining = max; 99 uint32_t status; 100 101 #define MAX_RESETS_PER_READ 1 102 uint32_t num_resets = 0; 103 104 #define MAX_IDLE_TIME (1 * HZ) 105 unsigned long idle_endtime = jiffies + MAX_IDLE_TIME; 106 107 while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) { 108 109 /* Is RNG sane? If not, reset it. */ 110 status = ioread32(priv->base + RNG_INT_STATUS_OFFSET); 111 if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK | 112 RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) { 113 114 if (num_resets >= MAX_RESETS_PER_READ) 115 return max - num_remaining; 116 117 iproc_rng200_restart(priv->base); 118 num_resets++; 119 } 120 121 /* Are there any random numbers available? */ 122 if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) & 123 RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) { 124 125 if (num_remaining >= sizeof(uint32_t)) { 126 /* Buffer has room to store entire word */ 127 *(uint32_t *)buf = ioread32(priv->base + 128 RNG_FIFO_DATA_OFFSET); 129 buf += sizeof(uint32_t); 130 num_remaining -= sizeof(uint32_t); 131 } else { 132 /* Buffer can only store partial word */ 133 uint32_t rnd_number = ioread32(priv->base + 134 RNG_FIFO_DATA_OFFSET); 135 memcpy(buf, &rnd_number, num_remaining); 136 buf += num_remaining; 137 num_remaining = 0; 138 } 139 140 /* Reset the IDLE timeout */ 141 idle_endtime = jiffies + MAX_IDLE_TIME; 142 } else { 143 if (!wait) 144 /* Cannot wait, return immediately */ 145 return max - num_remaining; 146 147 /* Can wait, give others chance to run */ 148 usleep_range(min(num_remaining * 10, 500U), 500); 149 } 150 } 151 152 return max - num_remaining; 153 } 154 155 static int iproc_rng200_init(struct hwrng *rng) 156 { 157 struct iproc_rng200_dev *priv = to_rng_priv(rng); 158 uint32_t val; 159 160 /* Setup RNG. */ 161 val = ioread32(priv->base + RNG_CTRL_OFFSET); 162 val &= ~RNG_CTRL_RNG_RBGEN_MASK; 163 val |= RNG_CTRL_RNG_RBGEN_ENABLE; 164 iowrite32(val, priv->base + RNG_CTRL_OFFSET); 165 166 return 0; 167 } 168 169 static void iproc_rng200_cleanup(struct hwrng *rng) 170 { 171 struct iproc_rng200_dev *priv = to_rng_priv(rng); 172 uint32_t val; 173 174 /* Disable RNG hardware */ 175 val = ioread32(priv->base + RNG_CTRL_OFFSET); 176 val &= ~RNG_CTRL_RNG_RBGEN_MASK; 177 val |= RNG_CTRL_RNG_RBGEN_DISABLE; 178 iowrite32(val, priv->base + RNG_CTRL_OFFSET); 179 } 180 181 static int iproc_rng200_probe(struct platform_device *pdev) 182 { 183 struct iproc_rng200_dev *priv; 184 struct resource *res; 185 struct device *dev = &pdev->dev; 186 int ret; 187 188 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 189 if (!priv) 190 return -ENOMEM; 191 192 /* Map peripheral */ 193 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 194 if (!res) { 195 dev_err(dev, "failed to get rng resources\n"); 196 return -EINVAL; 197 } 198 199 priv->base = devm_ioremap_resource(dev, res); 200 if (IS_ERR(priv->base)) { 201 dev_err(dev, "failed to remap rng regs\n"); 202 return PTR_ERR(priv->base); 203 } 204 205 priv->rng.name = "iproc-rng200", 206 priv->rng.read = iproc_rng200_read, 207 priv->rng.init = iproc_rng200_init, 208 priv->rng.cleanup = iproc_rng200_cleanup, 209 210 /* Register driver */ 211 ret = devm_hwrng_register(dev, &priv->rng); 212 if (ret) { 213 dev_err(dev, "hwrng registration failed\n"); 214 return ret; 215 } 216 217 dev_info(dev, "hwrng registered\n"); 218 219 return 0; 220 } 221 222 static const struct of_device_id iproc_rng200_of_match[] = { 223 { .compatible = "brcm,bcm7278-rng200", }, 224 { .compatible = "brcm,iproc-rng200", }, 225 {}, 226 }; 227 MODULE_DEVICE_TABLE(of, iproc_rng200_of_match); 228 229 static struct platform_driver iproc_rng200_driver = { 230 .driver = { 231 .name = "iproc-rng200", 232 .of_match_table = iproc_rng200_of_match, 233 }, 234 .probe = iproc_rng200_probe, 235 }; 236 module_platform_driver(iproc_rng200_driver); 237 238 MODULE_AUTHOR("Broadcom"); 239 MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver"); 240 MODULE_LICENSE("GPL v2"); 241