Re: [PATCH v1] drivers: rng: add check status bit feature

Hi,

On 21/06/2023 12:24, Alexey Romanov wrote:

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.

Thanks for the change, but could you add this first in Linux with the associated bindings update and DT changes then port it to U-boot ?

Thanks, Neil

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,
  

  }, {}, };