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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (c) 2010-2012 Broadcom. All rights reserved.4 * Copyright (c) 2013 Lubomir Rintel5 */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 0x018#define RNG_STATUS 0x419#define RNG_DATA 0x820#define RNG_INT_MASK 0x1021 22/* enable rng */23#define RNG_RBGEN 0x124 25/* the initial numbers generated are "less random" so will be discarded */26#define RNG_WARMUP_COUNT 0x4000027 28#define RNG_INT_OFF 0x129 30struct 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 38static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)39{40 return container_of(rng, struct bcm2835_rng_priv, rng);41}42 43static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset)44{45 /* MIPS chips strapped for BE will automagically configure the46 * 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 else51 return readl(priv->base + offset);52}53 54static 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 else60 writel(val, priv->base + offset);61}62 63static 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 86static 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 clk_disable_unprepare(priv->clk);99 return ret;100 }101 102 if (priv->mask_interrupts) {103 /* mask the interrupt */104 val = rng_readl(priv, RNG_INT_MASK);105 val |= RNG_INT_OFF;106 rng_writel(priv, val, RNG_INT_MASK);107 }108 109 /* set warm-up count & enable */110 rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);111 rng_writel(priv, RNG_RBGEN, RNG_CTRL);112 113 return ret;114}115 116static void bcm2835_rng_cleanup(struct hwrng *rng)117{118 struct bcm2835_rng_priv *priv = to_rng_priv(rng);119 120 /* disable rng hardware */121 rng_writel(priv, 0, RNG_CTRL);122 123 clk_disable_unprepare(priv->clk);124}125 126struct bcm2835_rng_of_data {127 bool mask_interrupts;128};129 130static const struct bcm2835_rng_of_data nsp_rng_of_data = {131 .mask_interrupts = true,132};133 134static const struct of_device_id bcm2835_rng_of_match[] = {135 { .compatible = "brcm,bcm2835-rng"},136 { .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data },137 { .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data },138 { .compatible = "brcm,bcm6368-rng"},139 {},140};141 142static int bcm2835_rng_probe(struct platform_device *pdev)143{144 const struct bcm2835_rng_of_data *of_data;145 struct device *dev = &pdev->dev;146 const struct of_device_id *rng_id;147 struct bcm2835_rng_priv *priv;148 int err;149 150 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);151 if (!priv)152 return -ENOMEM;153 154 /* map peripheral */155 priv->base = devm_platform_ioremap_resource(pdev, 0);156 if (IS_ERR(priv->base))157 return PTR_ERR(priv->base);158 159 /* Clock is optional on most platforms */160 priv->clk = devm_clk_get_optional(dev, NULL);161 if (IS_ERR(priv->clk))162 return PTR_ERR(priv->clk);163 164 priv->reset = devm_reset_control_get_optional_exclusive(dev, NULL);165 if (IS_ERR(priv->reset))166 return PTR_ERR(priv->reset);167 168 priv->rng.name = pdev->name;169 priv->rng.init = bcm2835_rng_init;170 priv->rng.read = bcm2835_rng_read;171 priv->rng.cleanup = bcm2835_rng_cleanup;172 173 if (dev_of_node(dev)) {174 rng_id = of_match_node(bcm2835_rng_of_match, dev->of_node);175 if (!rng_id)176 return -EINVAL;177 178 /* Check for rng init function, execute it */179 of_data = rng_id->data;180 if (of_data)181 priv->mask_interrupts = of_data->mask_interrupts;182 }183 184 /* register driver */185 err = devm_hwrng_register(dev, &priv->rng);186 if (err)187 dev_err(dev, "hwrng registration failed\n");188 else189 dev_info(dev, "hwrng registered\n");190 191 return err;192}193 194MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);195 196static const struct platform_device_id bcm2835_rng_devtype[] = {197 { .name = "bcm2835-rng" },198 { .name = "bcm63xx-rng" },199 { /* sentinel */ }200};201MODULE_DEVICE_TABLE(platform, bcm2835_rng_devtype);202 203static struct platform_driver bcm2835_rng_driver = {204 .driver = {205 .name = "bcm2835-rng",206 .of_match_table = bcm2835_rng_of_match,207 },208 .probe = bcm2835_rng_probe,209 .id_table = bcm2835_rng_devtype,210};211module_platform_driver(bcm2835_rng_driver);212 213MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");214MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");215MODULE_LICENSE("GPL v2");216