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1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2020 Silex Insight3 4#include <linux/delay.h>5#include <linux/hw_random.h>6#include <linux/io.h>7#include <linux/iopoll.h>8#include <linux/kernel.h>9#include <linux/mod_devicetable.h>10#include <linux/module.h>11#include <linux/platform_device.h>12#include <linux/workqueue.h>13 14#define BA431_RESET_DELAY 1 /* usec */15#define BA431_RESET_READ_STATUS_TIMEOUT 1000 /* usec */16#define BA431_RESET_READ_STATUS_INTERVAL 10 /* usec */17#define BA431_READ_RETRY_INTERVAL 1 /* usec */18 19#define BA431_REG_CTRL 0x0020#define BA431_REG_FIFO_LEVEL 0x0421#define BA431_REG_STATUS 0x3022#define BA431_REG_FIFODATA 0x8023 24#define BA431_CTRL_ENABLE BIT(0)25#define BA431_CTRL_SOFTRESET BIT(8)26 27#define BA431_STATUS_STATE_MASK (BIT(1) | BIT(2) | BIT(3))28#define BA431_STATUS_STATE_OFFSET 129 30enum ba431_state {31 BA431_STATE_RESET,32 BA431_STATE_STARTUP,33 BA431_STATE_FIFOFULLON,34 BA431_STATE_FIFOFULLOFF,35 BA431_STATE_RUNNING,36 BA431_STATE_ERROR37};38 39struct ba431_trng {40 struct device *dev;41 void __iomem *base;42 struct hwrng rng;43 atomic_t reset_pending;44 struct work_struct reset_work;45};46 47static inline u32 ba431_trng_read_reg(struct ba431_trng *ba431, u32 reg)48{49 return ioread32(ba431->base + reg);50}51 52static inline void ba431_trng_write_reg(struct ba431_trng *ba431, u32 reg,53 u32 val)54{55 iowrite32(val, ba431->base + reg);56}57 58static inline enum ba431_state ba431_trng_get_state(struct ba431_trng *ba431)59{60 u32 status = ba431_trng_read_reg(ba431, BA431_REG_STATUS);61 62 return (status & BA431_STATUS_STATE_MASK) >> BA431_STATUS_STATE_OFFSET;63}64 65static int ba431_trng_is_in_error(struct ba431_trng *ba431)66{67 enum ba431_state state = ba431_trng_get_state(ba431);68 69 if ((state < BA431_STATE_STARTUP) ||70 (state >= BA431_STATE_ERROR))71 return 1;72 73 return 0;74}75 76static int ba431_trng_reset(struct ba431_trng *ba431)77{78 int ret;79 80 /* Disable interrupts, random generation and enable the softreset */81 ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_SOFTRESET);82 udelay(BA431_RESET_DELAY);83 ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_ENABLE);84 85 /* Wait until the state changed */86 if (readx_poll_timeout(ba431_trng_is_in_error, ba431, ret, !ret,87 BA431_RESET_READ_STATUS_INTERVAL,88 BA431_RESET_READ_STATUS_TIMEOUT)) {89 dev_err(ba431->dev, "reset failed (state: %d)\n",90 ba431_trng_get_state(ba431));91 return -ETIMEDOUT;92 }93 94 dev_info(ba431->dev, "reset done\n");95 96 return 0;97}98 99static void ba431_trng_reset_work(struct work_struct *work)100{101 struct ba431_trng *ba431 = container_of(work, struct ba431_trng,102 reset_work);103 ba431_trng_reset(ba431);104 atomic_set(&ba431->reset_pending, 0);105}106 107static void ba431_trng_schedule_reset(struct ba431_trng *ba431)108{109 if (atomic_cmpxchg(&ba431->reset_pending, 0, 1))110 return;111 112 schedule_work(&ba431->reset_work);113}114 115static int ba431_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)116{117 struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);118 u32 *data = buf;119 unsigned int level, i;120 int n = 0;121 122 while (max > 0) {123 level = ba431_trng_read_reg(ba431, BA431_REG_FIFO_LEVEL);124 if (!level) {125 if (ba431_trng_is_in_error(ba431)) {126 ba431_trng_schedule_reset(ba431);127 break;128 }129 130 if (!wait)131 break;132 133 udelay(BA431_READ_RETRY_INTERVAL);134 continue;135 }136 137 i = level;138 do {139 data[n++] = ba431_trng_read_reg(ba431,140 BA431_REG_FIFODATA);141 max -= sizeof(*data);142 } while (--i && (max > 0));143 144 if (ba431_trng_is_in_error(ba431)) {145 n -= (level - i);146 ba431_trng_schedule_reset(ba431);147 break;148 }149 }150 151 n *= sizeof(data);152 return (n || !wait) ? n : -EIO;153}154 155static void ba431_trng_cleanup(struct hwrng *rng)156{157 struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);158 159 ba431_trng_write_reg(ba431, BA431_REG_CTRL, 0);160 cancel_work_sync(&ba431->reset_work);161}162 163static int ba431_trng_init(struct hwrng *rng)164{165 struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);166 167 return ba431_trng_reset(ba431);168}169 170static int ba431_trng_probe(struct platform_device *pdev)171{172 struct ba431_trng *ba431;173 int ret;174 175 ba431 = devm_kzalloc(&pdev->dev, sizeof(*ba431), GFP_KERNEL);176 if (!ba431)177 return -ENOMEM;178 179 ba431->dev = &pdev->dev;180 181 ba431->base = devm_platform_ioremap_resource(pdev, 0);182 if (IS_ERR(ba431->base))183 return PTR_ERR(ba431->base);184 185 atomic_set(&ba431->reset_pending, 0);186 INIT_WORK(&ba431->reset_work, ba431_trng_reset_work);187 ba431->rng.name = pdev->name;188 ba431->rng.init = ba431_trng_init;189 ba431->rng.cleanup = ba431_trng_cleanup;190 ba431->rng.read = ba431_trng_read;191 192 ret = devm_hwrng_register(&pdev->dev, &ba431->rng);193 if (ret)194 return dev_err_probe(&pdev->dev, ret, "BA431 registration failed\n");195 196 dev_info(&pdev->dev, "BA431 TRNG registered\n");197 198 return 0;199}200 201static const struct of_device_id ba431_trng_dt_ids[] = {202 { .compatible = "silex-insight,ba431-rng" },203 { /* sentinel */ }204};205MODULE_DEVICE_TABLE(of, ba431_trng_dt_ids);206 207static struct platform_driver ba431_trng_driver = {208 .driver = {209 .name = "ba431-rng",210 .of_match_table = ba431_trng_dt_ids,211 },212 .probe = ba431_trng_probe,213};214 215module_platform_driver(ba431_trng_driver);216 217MODULE_AUTHOR("Olivier Sobrie <olivier@sobrie.be>");218MODULE_DESCRIPTION("TRNG driver for Silex Insight BA431");219MODULE_LICENSE("GPL");220