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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Copyright 2020, Matthias Brugger <mbrugger@suse.com>
- *
- * Driver for Raspberry Pi hardware random number generator
- */
- #include <common.h>
- #include <dm.h>
- #include <linux/delay.h>
- #include <rng.h>
- #include <asm/io.h>
- #define usleep_range(a, b) udelay((b))
- #define RNG_CTRL_OFFSET 0x00
- #define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF
- #define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001
- #define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000
- #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_NIST_FAIL_IRQ_MASK 0x00000020
- #define RNG_FIFO_DATA_OFFSET 0x20
- #define RNG_FIFO_COUNT_OFFSET 0x24
- #define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF
- struct iproc_rng200_plat {
- void __iomem *base;
- };
- static void iproc_rng200_enable(struct iproc_rng200_plat *pdata, bool enable)
- {
- void __iomem *rng_base = pdata->base;
- u32 val;
- val = readl(rng_base + RNG_CTRL_OFFSET);
- val &= ~RNG_CTRL_RNG_RBGEN_MASK;
- if (enable)
- val |= RNG_CTRL_RNG_RBGEN_ENABLE;
- else
- val &= ~RNG_CTRL_RNG_RBGEN_ENABLE;
- writel(val, rng_base + RNG_CTRL_OFFSET);
- }
- static void iproc_rng200_restart(struct iproc_rng200_plat *pdata)
- {
- void __iomem *rng_base = pdata->base;
- u32 val;
- iproc_rng200_enable(pdata, false);
- /* Clear all interrupt status */
- writel(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
- /* Reset RNG and RBG */
- val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
- val |= RBG_SOFT_RESET;
- writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
- val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
- val |= RNG_SOFT_RESET;
- writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
- val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
- val &= ~RNG_SOFT_RESET;
- writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
- val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
- val &= ~RBG_SOFT_RESET;
- writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
- iproc_rng200_enable(pdata, true);
- }
- static int iproc_rng200_read(struct udevice *dev, void *data, size_t len)
- {
- struct iproc_rng200_plat *priv = dev_get_plat(dev);
- char *buf = (char *)data;
- u32 num_remaining = len;
- u32 status;
- #define MAX_RESETS_PER_READ 1
- u32 num_resets = 0;
- while (num_remaining > 0) {
- /* Is RNG sane? If not, reset it. */
- status = readl(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 len - num_remaining;
- iproc_rng200_restart(priv);
- num_resets++;
- }
- /* Are there any random numbers available? */
- if ((readl(priv->base + RNG_FIFO_COUNT_OFFSET) &
- RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
- if (num_remaining >= sizeof(u32)) {
- /* Buffer has room to store entire word */
- *(u32 *)buf = readl(priv->base +
- RNG_FIFO_DATA_OFFSET);
- buf += sizeof(u32);
- num_remaining -= sizeof(u32);
- } else {
- /* Buffer can only store partial word */
- u32 rnd_number = readl(priv->base +
- RNG_FIFO_DATA_OFFSET);
- memcpy(buf, &rnd_number, num_remaining);
- buf += num_remaining;
- num_remaining = 0;
- }
- } else {
- /* Can wait, give others chance to run */
- usleep_range(min(num_remaining * 10, 500U), 500);
- }
- }
- return 0;
- }
- static int iproc_rng200_probe(struct udevice *dev)
- {
- struct iproc_rng200_plat *priv = dev_get_plat(dev);
- iproc_rng200_enable(priv, true);
- return 0;
- }
- static int iproc_rng200_remove(struct udevice *dev)
- {
- struct iproc_rng200_plat *priv = dev_get_plat(dev);
- iproc_rng200_enable(priv, false);
- return 0;
- }
- static int iproc_rng200_of_to_plat(struct udevice *dev)
- {
- struct iproc_rng200_plat *pdata = dev_get_plat(dev);
- pdata->base = devfdt_map_physmem(dev, sizeof(void *));
- if (!pdata->base)
- return -ENODEV;
- return 0;
- }
- static const struct dm_rng_ops iproc_rng200_ops = {
- .read = iproc_rng200_read,
- };
- static const struct udevice_id iproc_rng200_rng_match[] = {
- { .compatible = "brcm,bcm2711-rng200", },
- { .compatible = "brcm,iproc-rng200", },
- {},
- };
- U_BOOT_DRIVER(iproc_rng200_rng) = {
- .name = "iproc_rng200-rng",
- .id = UCLASS_RNG,
- .of_match = iproc_rng200_rng_match,
- .ops = &iproc_rng200_ops,
- .probe = iproc_rng200_probe,
- .remove = iproc_rng200_remove,
- .priv_auto = sizeof(struct iproc_rng200_plat),
- .of_to_plat = iproc_rng200_of_to_plat,
- };
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