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drivers: rng: add support for Meson S4

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For some Amlogic SOC's, mechanism to obtain random number
has been changed. For example, S4 now uses status bit waiting algo.

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231012075828.22685-2-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
This commit is contained in:
Alexey Romanov 2023-10-12 10:58:25 +03:00 committed by Neil Armstrong
parent 7b4116f8f7
commit a92345610e
1 changed files with 71 additions and 1 deletions
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72
drivers/rng/meson-rng.c
View file

@ -10,10 +10,23 @@
#include <dm.h>
#include <rng.h>
#include <asm/io.h>
#include <linux/iopoll.h>
#define RNG_DATA 0x00
#define RNG_S4_DATA 0x08
#define RNG_S4_CFG 0x00
#define RUN_BIT BIT(0)
#define SEED_READY_STS_BIT BIT(31)
struct meson_rng_priv {
u32 (*read)(fdt_addr_t base);
};
struct meson_rng_plat {
fdt_addr_t base;
struct clk clk;
struct meson_rng_priv *priv;
};
/**
@ -27,10 +40,11 @@ struct meson_rng_plat {
static int meson_rng_read(struct udevice *dev, void *data, size_t len)
{
struct meson_rng_plat *pdata = dev_get_plat(dev);
struct meson_rng_priv *priv = pdata->priv;
char *buffer = (char *)data;
while (len) {
u32 rand = readl(pdata->base);
u32 rand = priv->read(pdata->base);
size_t step;
if (len >= 4)
@ -44,6 +58,47 @@ static int meson_rng_read(struct udevice *dev, void *data, size_t len)
return 0;
}
static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
{
u32 status = 0;
int ret;
ret = readl_relaxed_poll_timeout(cfg_addr,
status, !(status & bit),
10000);
if (ret)
return -EBUSY;
return 0;
}
static u32 meson_common_rng_read(fdt_addr_t base)
{
return readl(base);
}
static u32 meson_s4_rng_read(fdt_addr_t base)
{
void __iomem *cfg_addr = (void *)base + RNG_S4_CFG;
int err;
writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);
err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
if (err) {
pr_err("Seed isn't ready, try again\n");
return err;
}
err = meson_rng_wait_status(cfg_addr, RUN_BIT);
if (err) {
pr_err("Can't get random number, try again\n");
return err;
}
return readl_relaxed(base + RNG_S4_DATA);
}
/**
* meson_rng_probe() - probe rng device
*
@ -59,6 +114,8 @@ static int meson_rng_probe(struct udevice *dev)
if (err)
return err;
pdata->priv = (struct meson_rng_priv *)dev_get_driver_data(dev);
return 0;
}
@ -102,9 +159,22 @@ static const struct dm_rng_ops meson_rng_ops = {
.read = meson_rng_read,
};
static const struct meson_rng_priv meson_rng_priv = {
.read = meson_common_rng_read,
};
static const struct meson_rng_priv meson_rng_priv_s4 = {
.read = meson_s4_rng_read,
};
static const struct udevice_id meson_rng_match[] = {
{
.compatible = "amlogic,meson-rng",
.data = (ulong)&meson_rng_priv,
},
{
.compatible = "amlogic,meson-s4-rng",
.data = (ulong)&meson_rng_priv_s4,
},
{},
};