On Wed, 2025-02-26 at 16:44 +0000, André Draszik wrote:
> Linux supports a couple different reset modes, but this driver here
> doesn't distinguish between them and issues the same syscon register
> write irrespective of the reset mode requested by the kernel.
>
> Update this driver to support most of Linux' reset modes: cold, hard,
> warm, and soft.
>
> The actions to take for these are taken from DT, and are all new
> optional properties. The property names match the existing properties
> supported but should be prefixed with the reset mode.
>
> This change is meant to be backwards compatible with existing DTs, and
> if Linux requests a reset mode that this driver doesn't support, or
> that the DT doesn't specify, the reset is triggered using the fallback
> / default entry.
>
> As an example why this is useful, other than properly supporting the
> Linux reboot= kernel command line option or sysfs entry, this change
> allows platforms to e.g. default to a more secure cold-reset, but
> also to do a warm-reset in case RAM contents needs to be retained
> across the reset.
>
> Signed-off-by: André Draszik <andre.draszik@xxxxxxxxxx>
> ---
> drivers/power/reset/syscon-reboot.c | 88 ++++++++++++++++++++++++++++++++-----
> 1 file changed, 77 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/power/reset/syscon-reboot.c b/drivers/power/reset/syscon-reboot.c
> index d623d77e657e4c233d8ae88bb099bee13c48a9ef..1d3d8a3265ae8005c685b42d3e554bd8bb0047ea 100644
> --- a/drivers/power/reset/syscon-reboot.c
> +++ b/drivers/power/reset/syscon-reboot.c
> @@ -14,11 +14,29 @@
> #include <linux/reboot.h>
> #include <linux/regmap.h>
>
> -struct syscon_reboot_context {
> - struct regmap *map;
> +/* REBOOT_GPIO doesn't make sense for syscon-reboot */
> +static const struct {
> + enum reboot_mode mode;
> + const char *prefix;
> +} prefix_map[] = {
> + { .mode = REBOOT_COLD, .prefix = "cold" },
> + { .mode = REBOOT_WARM, .prefix = "warm" },
> + { .mode = REBOOT_HARD, .prefix = "hard" },
> + { .mode = REBOOT_SOFT, .prefix = "soft" },
> +};
> +
> +struct reboot_mode_bits {
> u32 offset;
> u32 value;
> u32 mask;
> + bool valid;
> +};
> +
> +struct syscon_reboot_context {
> + struct regmap *map;
> +
> + struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1];
> + struct reboot_mode_bits catchall;
> struct notifier_block restart_handler;
> };
>
> @@ -28,9 +46,16 @@ static int syscon_restart_handle(struct notifier_block *this,
> struct syscon_reboot_context *ctx =
> container_of(this, struct syscon_reboot_context,
> restart_handler);
> + const struct reboot_mode_bits *mode_bits;
> +
> + if (mode < ARRAY_SIZE(ctx->mode_bits) && ctx->mode_bits[mode].valid)
> + mode_bits = &ctx->mode_bits[mode];
> + else
> + mode_bits = &ctx->catchall;
>
> /* Issue the reboot */
> - regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
> + regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask,
> + mode_bits->value);
>
> mdelay(1000);
>
> @@ -45,6 +70,7 @@ static int syscon_reboot_probe(struct platform_device *pdev)
> int mask_err, value_err;
> int priority;
> int err;
> + char prop[32];
>
> ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
> if (!ctx)
> @@ -60,12 +86,52 @@ static int syscon_reboot_probe(struct platform_device *pdev)
> if (of_property_read_s32(pdev->dev.of_node, "priority", &priority))
> priority = 192;
>
> - if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
> - if (of_property_read_u32(pdev->dev.of_node, "reg", &ctx->offset))
> + BUILD_BUG_ON(ARRAY_SIZE(prefix_map) != ARRAY_SIZE(ctx->mode_bits));
> + BUILD_BUG_ON(ARRAY_SIZE(ctx->mode_bits) <= REBOOT_COLD);
> + BUILD_BUG_ON(ARRAY_SIZE(ctx->mode_bits) <= REBOOT_WARM);
> + BUILD_BUG_ON(ARRAY_SIZE(ctx->mode_bits) <= REBOOT_HARD);
> + BUILD_BUG_ON(ARRAY_SIZE(ctx->mode_bits) <= REBOOT_SOFT);
> +
> + for (int i = 0; i < ARRAY_SIZE(prefix_map); ++i) {
> + const char * const prefix = prefix_map[i].prefix;
> + struct reboot_mode_bits * const mode_bits =
> + &ctx->mode_bits[prefix_map[i].mode];
> +
> + snprintf(prop, sizeof(prop), "%s-offset", prefix);
> + if (of_property_read_u32(pdev->dev.of_node, "offset",
> + &mode_bits->offset))
> + continue;
It should also check the %-reg property, and it needs
to use prop instead of "offset" in of_property_read_u32().
A.
