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1// SPDX-License-Identifier: GPL-2.0-only2/*3* Copyright (C) 2015 Broadcom Corporation4*5*/6/*7 * DESCRIPTION: The Broadcom iProc RNG200 Driver8 */9 10#include <linux/hw_random.h>11#include <linux/init.h>12#include <linux/io.h>13#include <linux/kernel.h>14#include <linux/module.h>15#include <linux/mod_devicetable.h>16#include <linux/platform_device.h>17#include <linux/delay.h>18 19/* Registers */20#define RNG_CTRL_OFFSET 0x0021#define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF22#define RNG_CTRL_RNG_RBGEN_ENABLE 0x0000000123 24#define RNG_SOFT_RESET_OFFSET 0x0425#define RNG_SOFT_RESET 0x0000000126 27#define RBG_SOFT_RESET_OFFSET 0x0828#define RBG_SOFT_RESET 0x0000000129 30#define RNG_INT_STATUS_OFFSET 0x1831#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x8000000032#define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x0002000033#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x0000002034#define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x0000000135 36#define RNG_FIFO_DATA_OFFSET 0x2037 38#define RNG_FIFO_COUNT_OFFSET 0x2439#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF40 41struct iproc_rng200_dev {42 struct hwrng rng;43 void __iomem *base;44};45 46#define to_rng_priv(rng) container_of(rng, struct iproc_rng200_dev, rng)47 48static void iproc_rng200_enable_set(void __iomem *rng_base, bool enable)49{50 u32 val;51 52 val = ioread32(rng_base + RNG_CTRL_OFFSET);53 val &= ~RNG_CTRL_RNG_RBGEN_MASK;54 55 if (enable)56 val |= RNG_CTRL_RNG_RBGEN_ENABLE;57 58 iowrite32(val, rng_base + RNG_CTRL_OFFSET);59}60 61static void iproc_rng200_restart(void __iomem *rng_base)62{63 uint32_t val;64 65 iproc_rng200_enable_set(rng_base, false);66 67 /* Clear all interrupt status */68 iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);69 70 /* Reset RNG and RBG */71 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);72 val |= RBG_SOFT_RESET;73 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);74 75 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);76 val |= RNG_SOFT_RESET;77 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);78 79 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);80 val &= ~RNG_SOFT_RESET;81 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);82 83 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);84 val &= ~RBG_SOFT_RESET;85 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);86 87 iproc_rng200_enable_set(rng_base, true);88}89 90static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,91 bool wait)92{93 struct iproc_rng200_dev *priv = to_rng_priv(rng);94 uint32_t num_remaining = max;95 uint32_t status;96 97 #define MAX_RESETS_PER_READ 198 uint32_t num_resets = 0;99 100 #define MAX_IDLE_TIME (1 * HZ)101 unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;102 103 while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {104 105 /* Is RNG sane? If not, reset it. */106 status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);107 if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |108 RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {109 110 if (num_resets >= MAX_RESETS_PER_READ)111 return max - num_remaining;112 113 iproc_rng200_restart(priv->base);114 num_resets++;115 }116 117 /* Are there any random numbers available? */118 if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &119 RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {120 121 if (num_remaining >= sizeof(uint32_t)) {122 /* Buffer has room to store entire word */123 *(uint32_t *)buf = ioread32(priv->base +124 RNG_FIFO_DATA_OFFSET);125 buf += sizeof(uint32_t);126 num_remaining -= sizeof(uint32_t);127 } else {128 /* Buffer can only store partial word */129 uint32_t rnd_number = ioread32(priv->base +130 RNG_FIFO_DATA_OFFSET);131 memcpy(buf, &rnd_number, num_remaining);132 buf += num_remaining;133 num_remaining = 0;134 }135 136 /* Reset the IDLE timeout */137 idle_endtime = jiffies + MAX_IDLE_TIME;138 } else {139 if (!wait)140 /* Cannot wait, return immediately */141 return max - num_remaining;142 143 /* Can wait, give others chance to run */144 usleep_range(min(num_remaining * 10, 500U), 500);145 }146 }147 148 return max - num_remaining;149}150 151static int iproc_rng200_init(struct hwrng *rng)152{153 struct iproc_rng200_dev *priv = to_rng_priv(rng);154 155 iproc_rng200_enable_set(priv->base, true);156 157 return 0;158}159 160static void iproc_rng200_cleanup(struct hwrng *rng)161{162 struct iproc_rng200_dev *priv = to_rng_priv(rng);163 164 iproc_rng200_enable_set(priv->base, false);165}166 167static int iproc_rng200_probe(struct platform_device *pdev)168{169 struct iproc_rng200_dev *priv;170 struct device *dev = &pdev->dev;171 int ret;172 173 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);174 if (!priv)175 return -ENOMEM;176 177 /* Map peripheral */178 priv->base = devm_platform_ioremap_resource(pdev, 0);179 if (IS_ERR(priv->base)) {180 dev_err(dev, "failed to remap rng regs\n");181 return PTR_ERR(priv->base);182 }183 184 dev_set_drvdata(dev, priv);185 186 priv->rng.name = "iproc-rng200";187 priv->rng.read = iproc_rng200_read;188 priv->rng.init = iproc_rng200_init;189 priv->rng.cleanup = iproc_rng200_cleanup;190 191 /* Register driver */192 ret = devm_hwrng_register(dev, &priv->rng);193 if (ret) {194 dev_err(dev, "hwrng registration failed\n");195 return ret;196 }197 198 dev_info(dev, "hwrng registered\n");199 200 return 0;201}202 203static int __maybe_unused iproc_rng200_suspend(struct device *dev)204{205 struct iproc_rng200_dev *priv = dev_get_drvdata(dev);206 207 iproc_rng200_cleanup(&priv->rng);208 209 return 0;210}211 212static int __maybe_unused iproc_rng200_resume(struct device *dev)213{214 struct iproc_rng200_dev *priv = dev_get_drvdata(dev);215 216 iproc_rng200_init(&priv->rng);217 218 return 0;219}220 221static const struct dev_pm_ops iproc_rng200_pm_ops = {222 SET_SYSTEM_SLEEP_PM_OPS(iproc_rng200_suspend, iproc_rng200_resume)223};224 225static const struct of_device_id iproc_rng200_of_match[] = {226 { .compatible = "brcm,bcm2711-rng200", },227 { .compatible = "brcm,bcm7211-rng200", },228 { .compatible = "brcm,bcm7278-rng200", },229 { .compatible = "brcm,iproc-rng200", },230 {},231};232MODULE_DEVICE_TABLE(of, iproc_rng200_of_match);233 234static struct platform_driver iproc_rng200_driver = {235 .driver = {236 .name = "iproc-rng200",237 .of_match_table = iproc_rng200_of_match,238 .pm = &iproc_rng200_pm_ops,239 },240 .probe = iproc_rng200_probe,241};242module_platform_driver(iproc_rng200_driver);243 244MODULE_AUTHOR("Broadcom");245MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver");246MODULE_LICENSE("GPL v2");247