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Message-Id: <20250227-syscon-reboot-reset-mode-v3-2-959ac53c338a@linaro.org>
Date: Thu, 27 Feb 2025 10:46:14 +0000
From: André Draszik <andre.draszik@...aro.org>
To: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>
Cc: Peter Griffin <peter.griffin@...aro.org>,
Tudor Ambarus <tudor.ambarus@...aro.org>,
Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com,
linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
André Draszik <andre.draszik@...aro.org>
Subject: [PATCH v3 2/2] power: reset: syscon-reboot: support different
reset modes
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@...aro.org>
---
drivers/power/reset/syscon-reboot.c | 96 ++++++++++++++++++++++++++++++++-----
1 file changed, 85 insertions(+), 11 deletions(-)
diff --git a/drivers/power/reset/syscon-reboot.c b/drivers/power/reset/syscon-reboot.c
index d623d77e657e4c233d8ae88bb099bee13c48a9ef..81b917a531b8bf04d7c5e7027bdc3290f2183eb0 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);
@@ -60,12 +85,61 @@ 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))
+ /* try to catch enum reboot_mode changing in any incompatible way */
+ 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];
+ char prop[32];
+
+ snprintf(prop, sizeof(prop), "%s-offset", prefix);
+ if (of_property_read_u32(pdev->dev.of_node, prop,
+ &mode_bits->offset)) {
+ snprintf(prop, sizeof(prop), "%s-reg", prefix);
+ if (of_property_read_u32(pdev->dev.of_node, prop,
+ &mode_bits->offset))
+ continue;
+ }
+
+ snprintf(prop, sizeof(prop), "%s-value", prefix);
+ if (of_property_read_u32(pdev->dev.of_node, prop,
+ &mode_bits->value)) {
+ /*
+ * unlike catchall below, don't support old binding
+ * here
+ */
+ dev_err(dev, "'%s' is mandatory\n", prop);
+ continue;
+ }
+
+ snprintf(prop, sizeof(prop), "%s-mask", prefix);
+ mask_err = of_property_read_u32(pdev->dev.of_node, prop,
+ &mode_bits->mask);
+
+ if (mask_err)
+ /* support value without mask */
+ mode_bits->mask = 0XFFFFFFFF;
+
+ mode_bits->valid = true;
+ }
+
+ /* catch-all entry */
+ if (of_property_read_u32(pdev->dev.of_node, "offset",
+ &ctx->catchall.offset))
+ if (of_property_read_u32(pdev->dev.of_node, "reg",
+ &ctx->catchall.offset))
return -EINVAL;
- value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
- mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
+ value_err = of_property_read_u32(pdev->dev.of_node, "value",
+ &ctx->catchall.value);
+ mask_err = of_property_read_u32(pdev->dev.of_node, "mask",
+ &ctx->catchall.mask);
if (value_err && mask_err) {
dev_err(dev, "unable to read 'value' and 'mask'");
return -EINVAL;
@@ -73,11 +147,11 @@ static int syscon_reboot_probe(struct platform_device *pdev)
if (value_err) {
/* support old binding */
- ctx->value = ctx->mask;
- ctx->mask = 0xFFFFFFFF;
+ ctx->catchall.value = ctx->catchall.mask;
+ ctx->catchall.mask = 0xFFFFFFFF;
} else if (mask_err) {
- /* support value without mask*/
- ctx->mask = 0xFFFFFFFF;
+ /* support value without mask */
+ ctx->catchall.mask = 0xFFFFFFFF;
}
ctx->restart_handler.notifier_call = syscon_restart_handle;
--
2.48.1.711.g2feabab25a-goog
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