bcm2835-rng.c (5247B)
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#include <linux/reset.h> 17 18#define RNG_CTRL 0x0 19#define RNG_STATUS 0x4 20#define RNG_DATA 0x8 21#define RNG_INT_MASK 0x10 22 23/* enable rng */ 24#define RNG_RBGEN 0x1 25 26/* the initial numbers generated are "less random" so will be discarded */ 27#define RNG_WARMUP_COUNT 0x40000 28 29#define RNG_INT_OFF 0x1 30 31struct bcm2835_rng_priv { 32 struct hwrng rng; 33 void __iomem *base; 34 bool mask_interrupts; 35 struct clk *clk; 36 struct reset_control *reset; 37}; 38 39static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) 40{ 41 return container_of(rng, struct bcm2835_rng_priv, rng); 42} 43 44static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) 45{ 46 /* MIPS chips strapped for BE will automagically configure the 47 * peripheral registers for CPU-native byte order. 48 */ 49 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) 50 return __raw_readl(priv->base + offset); 51 else 52 return readl(priv->base + offset); 53} 54 55static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, 56 u32 offset) 57{ 58 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) 59 __raw_writel(val, priv->base + offset); 60 else 61 writel(val, priv->base + offset); 62} 63 64static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, 65 bool wait) 66{ 67 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 68 u32 max_words = max / sizeof(u32); 69 u32 num_words, count; 70 71 while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { 72 if (!wait) 73 return 0; 74 cpu_relax(); 75 } 76 77 num_words = rng_readl(priv, RNG_STATUS) >> 24; 78 if (num_words > max_words) 79 num_words = max_words; 80 81 for (count = 0; count < num_words; count++) 82 ((u32 *)buf)[count] = rng_readl(priv, RNG_DATA); 83 84 return num_words * sizeof(u32); 85} 86 87static int bcm2835_rng_init(struct hwrng *rng) 88{ 89 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 90 int ret = 0; 91 u32 val; 92 93 ret = clk_prepare_enable(priv->clk); 94 if (ret) 95 return ret; 96 97 ret = reset_control_reset(priv->reset); 98 if (ret) 99 return ret; 100 101 if (priv->mask_interrupts) { 102 /* mask the interrupt */ 103 val = rng_readl(priv, RNG_INT_MASK); 104 val |= RNG_INT_OFF; 105 rng_writel(priv, val, RNG_INT_MASK); 106 } 107 108 /* set warm-up count & enable */ 109 rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); 110 rng_writel(priv, RNG_RBGEN, RNG_CTRL); 111 112 return ret; 113} 114 115static void bcm2835_rng_cleanup(struct hwrng *rng) 116{ 117 struct bcm2835_rng_priv *priv = to_rng_priv(rng); 118 119 /* disable rng hardware */ 120 rng_writel(priv, 0, RNG_CTRL); 121 122 clk_disable_unprepare(priv->clk); 123} 124 125struct bcm2835_rng_of_data { 126 bool mask_interrupts; 127}; 128 129static const struct bcm2835_rng_of_data nsp_rng_of_data = { 130 .mask_interrupts = true, 131}; 132 133static const struct of_device_id bcm2835_rng_of_match[] = { 134 { .compatible = "brcm,bcm2835-rng"}, 135 { .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data }, 136 { .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data }, 137 { .compatible = "brcm,bcm6368-rng"}, 138 {}, 139}; 140 141static int bcm2835_rng_probe(struct platform_device *pdev) 142{ 143 const struct bcm2835_rng_of_data *of_data; 144 struct device *dev = &pdev->dev; 145 const struct of_device_id *rng_id; 146 struct bcm2835_rng_priv *priv; 147 int err; 148 149 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 150 if (!priv) 151 return -ENOMEM; 152 153 platform_set_drvdata(pdev, priv); 154 155 /* map peripheral */ 156 priv->base = devm_platform_ioremap_resource(pdev, 0); 157 if (IS_ERR(priv->base)) 158 return PTR_ERR(priv->base); 159 160 /* Clock is optional on most platforms */ 161 priv->clk = devm_clk_get_optional(dev, NULL); 162 if (IS_ERR(priv->clk)) 163 return PTR_ERR(priv->clk); 164 165 priv->reset = devm_reset_control_get_optional_exclusive(dev, NULL); 166 if (IS_ERR(priv->reset)) 167 return PTR_ERR(priv->reset); 168 169 priv->rng.name = pdev->name; 170 priv->rng.init = bcm2835_rng_init; 171 priv->rng.read = bcm2835_rng_read; 172 priv->rng.cleanup = bcm2835_rng_cleanup; 173 174 if (dev_of_node(dev)) { 175 rng_id = of_match_node(bcm2835_rng_of_match, dev->of_node); 176 if (!rng_id) 177 return -EINVAL; 178 179 /* Check for rng init function, execute it */ 180 of_data = rng_id->data; 181 if (of_data) 182 priv->mask_interrupts = of_data->mask_interrupts; 183 } 184 185 /* register driver */ 186 err = devm_hwrng_register(dev, &priv->rng); 187 if (err) 188 dev_err(dev, "hwrng registration failed\n"); 189 else 190 dev_info(dev, "hwrng registered\n"); 191 192 return err; 193} 194 195MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); 196 197static const struct platform_device_id bcm2835_rng_devtype[] = { 198 { .name = "bcm2835-rng" }, 199 { .name = "bcm63xx-rng" }, 200 { /* sentinel */ } 201}; 202MODULE_DEVICE_TABLE(platform, bcm2835_rng_devtype); 203 204static struct platform_driver bcm2835_rng_driver = { 205 .driver = { 206 .name = "bcm2835-rng", 207 .of_match_table = bcm2835_rng_of_match, 208 }, 209 .probe = bcm2835_rng_probe, 210 .id_table = bcm2835_rng_devtype, 211}; 212module_platform_driver(bcm2835_rng_driver); 213 214MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 215MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); 216MODULE_LICENSE("GPL v2");