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