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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (C) 2015 Broadcom Corporation
- *
- */
- /*
- * DESCRIPTION: The Broadcom iProc RNG200 Driver
- */
- #include <linux/hw_random.h>
- #include <linux/init.h>
- #include <linux/io.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/of_address.h>
- #include <linux/of_platform.h>
- #include <linux/platform_device.h>
- #include <linux/delay.h>
- /* Registers */
- #define RNG_CTRL_OFFSET 0x00
- #define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF
- #define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001
- #define RNG_SOFT_RESET_OFFSET 0x04
- #define RNG_SOFT_RESET 0x00000001
- #define RBG_SOFT_RESET_OFFSET 0x08
- #define RBG_SOFT_RESET 0x00000001
- #define RNG_INT_STATUS_OFFSET 0x18
- #define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x80000000
- #define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x00020000
- #define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x00000020
- #define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x00000001
- #define RNG_FIFO_DATA_OFFSET 0x20
- #define RNG_FIFO_COUNT_OFFSET 0x24
- #define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF
- struct iproc_rng200_dev {
- struct hwrng rng;
- void __iomem *base;
- };
- #define to_rng_priv(rng) container_of(rng, struct iproc_rng200_dev, rng)
- static void iproc_rng200_enable_set(void __iomem *rng_base, bool enable)
- {
- u32 val;
- val = ioread32(rng_base + RNG_CTRL_OFFSET);
- val &= ~RNG_CTRL_RNG_RBGEN_MASK;
- if (enable)
- val |= RNG_CTRL_RNG_RBGEN_ENABLE;
- iowrite32(val, rng_base + RNG_CTRL_OFFSET);
- }
- static void iproc_rng200_restart(void __iomem *rng_base)
- {
- uint32_t val;
- iproc_rng200_enable_set(rng_base, false);
- /* Clear all interrupt status */
- iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
- /* Reset RNG and RBG */
- val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
- val |= RBG_SOFT_RESET;
- iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
- val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
- val |= RNG_SOFT_RESET;
- iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
- val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
- val &= ~RNG_SOFT_RESET;
- iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
- val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
- val &= ~RBG_SOFT_RESET;
- iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
- iproc_rng200_enable_set(rng_base, true);
- }
- static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,
- bool wait)
- {
- struct iproc_rng200_dev *priv = to_rng_priv(rng);
- uint32_t num_remaining = max;
- uint32_t status;
- #define MAX_RESETS_PER_READ 1
- uint32_t num_resets = 0;
- #define MAX_IDLE_TIME (1 * HZ)
- unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;
- while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {
- /* Is RNG sane? If not, reset it. */
- status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);
- if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |
- RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {
- if (num_resets >= MAX_RESETS_PER_READ)
- return max - num_remaining;
- iproc_rng200_restart(priv->base);
- num_resets++;
- }
- /* Are there any random numbers available? */
- if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &
- RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
- if (num_remaining >= sizeof(uint32_t)) {
- /* Buffer has room to store entire word */
- *(uint32_t *)buf = ioread32(priv->base +
- RNG_FIFO_DATA_OFFSET);
- buf += sizeof(uint32_t);
- num_remaining -= sizeof(uint32_t);
- } else {
- /* Buffer can only store partial word */
- uint32_t rnd_number = ioread32(priv->base +
- RNG_FIFO_DATA_OFFSET);
- memcpy(buf, &rnd_number, num_remaining);
- buf += num_remaining;
- num_remaining = 0;
- }
- /* Reset the IDLE timeout */
- idle_endtime = jiffies + MAX_IDLE_TIME;
- } else {
- if (!wait)
- /* Cannot wait, return immediately */
- return max - num_remaining;
- /* Can wait, give others chance to run */
- usleep_range(min(num_remaining * 10, 500U), 500);
- }
- }
- return max - num_remaining;
- }
- static int iproc_rng200_init(struct hwrng *rng)
- {
- struct iproc_rng200_dev *priv = to_rng_priv(rng);
- iproc_rng200_enable_set(priv->base, true);
- return 0;
- }
- static void iproc_rng200_cleanup(struct hwrng *rng)
- {
- struct iproc_rng200_dev *priv = to_rng_priv(rng);
- iproc_rng200_enable_set(priv->base, false);
- }
- static int iproc_rng200_probe(struct platform_device *pdev)
- {
- struct iproc_rng200_dev *priv;
- struct device *dev = &pdev->dev;
- int ret;
- priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
- if (!priv)
- return -ENOMEM;
- /* Map peripheral */
- priv->base = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(priv->base)) {
- dev_err(dev, "failed to remap rng regs\n");
- return PTR_ERR(priv->base);
- }
- dev_set_drvdata(dev, priv);
- priv->rng.name = "iproc-rng200";
- priv->rng.read = iproc_rng200_read;
- priv->rng.init = iproc_rng200_init;
- priv->rng.cleanup = iproc_rng200_cleanup;
- /* Register driver */
- ret = devm_hwrng_register(dev, &priv->rng);
- if (ret) {
- dev_err(dev, "hwrng registration failed\n");
- return ret;
- }
- dev_info(dev, "hwrng registered\n");
- return 0;
- }
- static int __maybe_unused iproc_rng200_suspend(struct device *dev)
- {
- struct iproc_rng200_dev *priv = dev_get_drvdata(dev);
- iproc_rng200_cleanup(&priv->rng);
- return 0;
- }
- static int __maybe_unused iproc_rng200_resume(struct device *dev)
- {
- struct iproc_rng200_dev *priv = dev_get_drvdata(dev);
- iproc_rng200_init(&priv->rng);
- return 0;
- }
- static const struct dev_pm_ops iproc_rng200_pm_ops = {
- SET_SYSTEM_SLEEP_PM_OPS(iproc_rng200_suspend, iproc_rng200_resume)
- };
- static const struct of_device_id iproc_rng200_of_match[] = {
- { .compatible = "brcm,bcm2711-rng200", },
- { .compatible = "brcm,bcm7211-rng200", },
- { .compatible = "brcm,bcm7278-rng200", },
- { .compatible = "brcm,iproc-rng200", },
- {},
- };
- MODULE_DEVICE_TABLE(of, iproc_rng200_of_match);
- static struct platform_driver iproc_rng200_driver = {
- .driver = {
- .name = "iproc-rng200",
- .of_match_table = iproc_rng200_of_match,
- .pm = &iproc_rng200_pm_ops,
- },
- .probe = iproc_rng200_probe,
- };
- module_platform_driver(iproc_rng200_driver);
- MODULE_AUTHOR("Broadcom");
- MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver");
- MODULE_LICENSE("GPL v2");
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