Re: [PATCH v1 09/16] reset: starfive-jh7100: Add StarFive JH7100 reset driver

Philipp Zabel
2021-10-12T14:31:50Z

On Tue, 2021-10-12 at 15:40 +0200, Emil Renner Berthing wrote:
> Add a driver for the StarFive JH7100 reset controller.
>
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> ---
> MAINTAINERS | 7 ++
> drivers/reset/Kconfig | 8 ++
> drivers/reset/Makefile | 1 +
> drivers/reset/reset-starfive-jh7100.c | 164 ++++++++++++++++++++++++++
> 4 files changed, 180 insertions(+)
> create mode 100644 drivers/reset/reset-starfive-jh7100.c
>
[...]
> diff --git a/drivers/reset/reset-starfive-jh7100.c b/drivers/reset/reset-starfive-jh7100.c
> new file mode 100644
> index 000000000000..26bc5b59c1f3
> --- /dev/null
> +++ b/drivers/reset/reset-starfive-jh7100.c
> @@ -0,0 +1,164 @@
[...]
> +static int jh7100_reset_update(struct reset_controller_dev *rcdev,
> + unsigned long id, bool assert)
> +{
> + struct jh7100_reset *data = jh7100_reset_from(rcdev);
> + unsigned long offset = id / 32;
> + void __iomem *reg_assert = data->base + JH7100_RESET_ASSERT0 + 4 * offset;
> + void __iomem *reg_status = data->base + JH7100_RESET_STATUS0 + 4 * offset;
> + u32 mask = BIT(id % 32);
> + u32 done = jh7100_reset_asserted[offset] & mask;
> + unsigned long flags;
> + u32 value;
> +
> + if (!assert)
> + done ^= mask;
> +
> + spin_lock_irqsave(&data->lock, flags);
> +
> + value = readl(reg_assert);
> + if (assert)
> + value |= mask;
> + else
> + value &= ~mask;
> + writel(value, reg_assert);
> +
> + do {
> + value = readl(reg_status) & mask;
> + } while (value != done);

Looking at the barebox driver, this could loop indefinitely if the
caller forgets to enable the corresponding peripheral clock. Maybe
use readl_poll_timeout() as a safety net.

regards
Philipp