1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2010-2012 Broadcom. All rights reserved. 4 * Copyright (c) 2013 Lubomir Rintel 5 */ 6 7 #include <linux/hw_random.h> 8 #include <linux/io.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/of.h> 12 #include <linux/platform_device.h> 13 #include <linux/printk.h> 14 #include <linux/clk.h> 15 #include <linux/reset.h> 16 17 #define RNG_CTRL 0x0 18 #define RNG_STATUS 0x4 19 #define RNG_DATA 0x8 20 #define RNG_INT_MASK 0x10 21 22 /* enable rng */ 23 #define RNG_RBGEN 0x1 24 25 /* the initial numbers generated are "less random" so will be discarded */ 26 #define RNG_WARMUP_COUNT 0x40000 27 28 #define RNG_INT_OFF 0x1 29 30 struct bcm2835_rng_priv { 31 struct hwrng rng; 32 void __iomem *base; 33 bool mask_interrupts; 34 struct clk *clk; 35 struct reset_control *reset; 36 }; 37 38 static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) 39 { 40 return container_of(rng, struct bcm2835_rng_priv, rng); 41 } 42 43 static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) 44 { 45 /* MIPS chips strapped for BE will automagically configure the 46 * peripheral registers for CPU-native byte order. 47 */ 48 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) 49 return __raw_readl(priv->base + offset); 50 else 51 return readl(priv->base + offset); 52 } 53 54 static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, 55 u32 offset) 56 { 57 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) 58 __raw_writel(val, priv->base + offset); 59 else 60 writel(val, priv->base + offset); 61 } 62 63 static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, 64 bool wait) 65 { 66 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 67 u32 max_words = max / sizeof(u32); 68 u32 num_words, count; 69 70 while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { 71 if (!wait) 72 return 0; 73 hwrng_yield(rng); 74 } 75 76 num_words = rng_readl(priv, RNG_STATUS) >> 24; 77 if (num_words > max_words) 78 num_words = max_words; 79 80 for (count = 0; count < num_words; count++) 81 ((u32 *)buf)[count] = rng_readl(priv, RNG_DATA); 82 83 return num_words * sizeof(u32); 84 } 85 86 static int bcm2835_rng_init(struct hwrng *rng) 87 { 88 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 89 int ret = 0; 90 u32 val; 91 92 ret = clk_prepare_enable(priv->clk); 93 if (ret) 94 return ret; 95 96 ret = reset_control_reset(priv->reset); 97 if (ret) 98 return ret; 99 100 if (priv->mask_interrupts) { 101 /* mask the interrupt */ 102 val = rng_readl(priv, RNG_INT_MASK); 103 val |= RNG_INT_OFF; 104 rng_writel(priv, val, RNG_INT_MASK); 105 } 106 107 /* set warm-up count & enable */ 108 rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); 109 rng_writel(priv, RNG_RBGEN, RNG_CTRL); 110 111 return ret; 112 } 113 114 static void bcm2835_rng_cleanup(struct hwrng *rng) 115 { 116 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 117 118 /* disable rng hardware */ 119 rng_writel(priv, 0, RNG_CTRL); 120 121 clk_disable_unprepare(priv->clk); 122 } 123 124 struct bcm2835_rng_of_data { 125 bool mask_interrupts; 126 }; 127 128 static const struct bcm2835_rng_of_data nsp_rng_of_data = { 129 .mask_interrupts = true, 130 }; 131 132 static const struct of_device_id bcm2835_rng_of_match[] = { 133 { .compatible = "brcm,bcm2835-rng"}, 134 { .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data }, 135 { .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data }, 136 { .compatible = "brcm,bcm6368-rng"}, 137 {}, 138 }; 139 140 static int bcm2835_rng_probe(struct platform_device *pdev) 141 { 142 const struct bcm2835_rng_of_data *of_data; 143 struct device *dev = &pdev->dev; 144 const struct of_device_id *rng_id; 145 struct bcm2835_rng_priv *priv; 146 int err; 147 148 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 149 if (!priv) 150 return -ENOMEM; 151 152 /* map peripheral */ 153 priv->base = devm_platform_ioremap_resource(pdev, 0); 154 if (IS_ERR(priv->base)) 155 return PTR_ERR(priv->base); 156 157 /* Clock is optional on most platforms */ 158 priv->clk = devm_clk_get_optional(dev, NULL); 159 if (IS_ERR(priv->clk)) 160 return PTR_ERR(priv->clk); 161 162 priv->reset = devm_reset_control_get_optional_exclusive(dev, NULL); 163 if (IS_ERR(priv->reset)) 164 return PTR_ERR(priv->reset); 165 166 priv->rng.name = pdev->name; 167 priv->rng.init = bcm2835_rng_init; 168 priv->rng.read = bcm2835_rng_read; 169 priv->rng.cleanup = bcm2835_rng_cleanup; 170 171 if (dev_of_node(dev)) { 172 rng_id = of_match_node(bcm2835_rng_of_match, dev->of_node); 173 if (!rng_id) 174 return -EINVAL; 175 176 /* Check for rng init function, execute it */ 177 of_data = rng_id->data; 178 if (of_data) 179 priv->mask_interrupts = of_data->mask_interrupts; 180 } 181 182 /* register driver */ 183 err = devm_hwrng_register(dev, &priv->rng); 184 if (err) 185 dev_err(dev, "hwrng registration failed\n"); 186 else 187 dev_info(dev, "hwrng registered\n"); 188 189 return err; 190 } 191 192 MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); 193 194 static const struct platform_device_id bcm2835_rng_devtype[] = { 195 { .name = "bcm2835-rng" }, 196 { .name = "bcm63xx-rng" }, 197 { /* sentinel */ } 198 }; 199 MODULE_DEVICE_TABLE(platform, bcm2835_rng_devtype); 200 201 static struct platform_driver bcm2835_rng_driver = { 202 .driver = { 203 .name = "bcm2835-rng", 204 .of_match_table = bcm2835_rng_of_match, 205 }, 206 .probe = bcm2835_rng_probe, 207 .id_table = bcm2835_rng_devtype, 208 }; 209 module_platform_driver(bcm2835_rng_driver); 210 211 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 212 MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); 213 MODULE_LICENSE("GPL v2"); 214