For some Amlogic SOC's, the mechanism for obtain a random number has been changed. For example, S4 now uses a status bit wait algo.
Signed-off-by: Alexey Romanov avromanov@sberdevices.ru --- drivers/rng/meson-rng.c | 73 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 67 insertions(+), 6 deletions(-)
diff --git a/drivers/rng/meson-rng.c b/drivers/rng/meson-rng.c index e0a1e8c7e04..3bf2eb9cf87 100644 --- a/drivers/rng/meson-rng.c +++ b/drivers/rng/meson-rng.c @@ -11,36 +11,82 @@ #include <rng.h> #include <asm/io.h>
+struct meson_rng_data { + bool check_status_bit; +}; + struct meson_rng_plat { fdt_addr_t base; struct clk clk; + struct meson_rng_data *data; };
+#define RETRY_CNT 100 +#define RNG_OUT_OFFSET 0x08 + +#define SEED_READY_STS_BIT 0 +#define RUN_BIT 31 + +static int meson_rng_wait_status(struct meson_rng_plat *pdata, int bit) +{ + u32 status; + u32 cnt = 0; + + pr_debug("Poll status of bit: %d\n", bit); + + do { + status = readl(pdata->base) & BIT(bit); + } while (status && (cnt++ < RETRY_CNT)); + + if (cnt == RETRY_CNT) { + pr_err("Can't get random number, try again"); + return -EBUSY; + } + + return 0; +} + /** * meson_rng_read() - fill buffer with random bytes * * @buffer: buffer to receive data * @size: size of buffer * - * Return: 0 + * Return: 0 on success or -errno in failure */ 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_data *rng_data = pdata->data; char *buffer = (char *)data; + int err;
while (len) { - u32 rand = readl(pdata->base); + u32 rand; size_t step;
- if (len >= 4) - step = 4; - else - step = len; + if (rng_data->check_status_bit) { + writel(readl(pdata->base) | BIT(SEED_READY_STS_BIT), pdata->base); + + err = meson_rng_wait_status(pdata, SEED_READY_STS_BIT); + if (err) + return err; + + err = meson_rng_wait_status(pdata, RUN_BIT); + if (err) + return err; + + rand = readl(pdata->base + RNG_OUT_OFFSET); + } else { + rand = readl(pdata->base); + } + + step = min_t(u32, len, 4); memcpy(buffer, &rand, step); buffer += step; len -= step; } + return 0; }
@@ -90,6 +136,8 @@ static int meson_rng_of_to_plat(struct udevice *dev) if (!pdata->base) return -ENODEV;
+ pdata->data = (struct meson_rng_data *)dev_get_driver_data(dev); + /* Get optional "core" clock */ err = clk_get_by_name_optional(dev, "core", &pdata->clk); if (err) @@ -102,9 +150,22 @@ static const struct dm_rng_ops meson_rng_ops = { .read = meson_rng_read, };
+static const struct meson_rng_data meson_rng_data = { + .check_status_bit = false, +}; + +static const struct meson_rng_data meson_rng_data_s4 = { + .check_status_bit = true, +}; + static const struct udevice_id meson_rng_match[] = { { .compatible = "amlogic,meson-rng", + .data = (ulong)&meson_rng_data, + }, + { + .compatible = "amlogic,meson-rng-s4", + .data = (ulong)&meson_rng_data_s4, }, {}, };