Hello all,
This patch series introduces the Power State Change Reasons (PSCR)
tracking framework and its related components into the kernel. The PSCR
framework is designed for systems where traditional methods of storing
power state change reasons, like PMICs or watchdogs, are inadequate. It
provides a structured way to store reasons for system shutdowns and
reboots, such as under-voltage or software-triggered events, in
non-volatile hardware storage.
These changes are critical for systems requiring detailed postmortem
analysis and where immediate power-down scenarios limit traditional
storage options. The framework also assists bootloaders and early-stage
system components in making informed recovery decisions.
Oleksij Rempel (7):
dt-bindings: power: reset: add generic PSCR binding trackers
power: reset: Introduce PSCR Tracking Framework for Non-Volatile
Storage
dt-bindings: power: reset: add bindings for NVMEM hardware storing
PSCR Data
nvmem: provide consumer access to cell size metrics
power: reset: add PSCR NVMEM Driver for Storing Power State Change
Reasons
regulator: set Power State Change Reason before
hw_protection_shutdown()
thermal: core: set Power State Change Reason before
hw_protection_shutdown()
.../bindings/power/reset/pscr-nvmem.yaml | 54 ++++
.../devicetree/bindings/power/reset/pscr.yaml | 51 ++++
drivers/nvmem/core.c | 25 ++
drivers/power/reset/Kconfig | 30 ++
drivers/power/reset/Makefile | 2 +
drivers/power/reset/pscr-nvmem.c | 100 +++++++
drivers/power/reset/pscr.c | 259 ++++++++++++++++++
drivers/regulator/core.c | 6 +
drivers/thermal/thermal_core.c | 2 +
include/linux/nvmem-consumer.h | 7 +
include/linux/pscr.h | 40 +++
11 files changed, 576 insertions(+)
create mode 100644 Documentation/devicetree/bindings/power/reset/pscr-nvmem.yaml
create mode 100644 Documentation/devicetree/bindings/power/reset/pscr.yaml
create mode 100644 drivers/power/reset/pscr-nvmem.c
create mode 100644 drivers/power/reset/pscr.c
create mode 100644 include/linux/pscr.h
--
2.39.2
This commit introduces the Power State Change Reasons (PSCR) tracking
framework into the kernel. The framework is vital for systems where
PMICs or watchdogs cannot provide information on power state changes. It
stores reasons for system shutdowns and reboots, like under-voltage or
software-triggered events, in non-volatile hardware storage. This
approach is essential for postmortem analysis in scenarios where
traditional storage methods (block devices, RAM) are not feasible. The
framework aids bootloaders and early-stage system components in recovery
decision-making, although it does not cover resets caused by hardware
issues like system freezes or watchdog timeouts.
Signed-off-by: Oleksij Rempel <[email protected]>
---
drivers/power/reset/Kconfig | 19 +++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/pscr.c | 259 +++++++++++++++++++++++++++++++++++
include/linux/pscr.h | 40 ++++++
4 files changed, 319 insertions(+)
create mode 100644 drivers/power/reset/pscr.c
create mode 100644 include/linux/pscr.h
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index fece990af4a7..da76e84302b9 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -305,3 +305,22 @@ config POWER_MLXBF
This driver supports reset or low power mode handling for Mellanox BlueField.
endif
+
+menuconfig PSCR
+ bool "Power State Change Reasons (PSCR) Tracking Framework"
+ help
+ Enables the Power State Change Reasons (PSCR) tracking framework.
+
+ This framework is designed to store reasons for system shutdowns or
+ reboots, like under voltage or software-triggered events, in non-volatile
+ hardware storage. It is particularly useful for postmortem analysis, where
+ traditional storage methods (like block devices or RAM) are not feasible
+ due to immediate power-down requirements or insufficient power to retain
+ data.
+
+ This is useful for bootloaders or other early-stage system components to
+ make recovery decisions based on the last known system state. Note that it
+ does not cover hardware-induced resets like system freezes or watchdog
+ timeouts.
+
+ If unsure, say N.
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index a95d1bd275d1..d9d744302c68 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_POWER_RESET_KEYSTONE) += keystone-reset.o
obj-$(CONFIG_POWER_RESET_SYSCON) += syscon-reboot.o
obj-$(CONFIG_POWER_RESET_SYSCON_POWEROFF) += syscon-poweroff.o
obj-$(CONFIG_POWER_RESET_RMOBILE) += rmobile-reset.o
+obj-$(CONFIG_PSCR) += pscr.o
obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
obj-$(CONFIG_POWER_RESET_SC27XX) += sc27xx-poweroff.o
diff --git a/drivers/power/reset/pscr.c b/drivers/power/reset/pscr.c
new file mode 100644
index 000000000000..7506ecbe1aad
--- /dev/null
+++ b/drivers/power/reset/pscr.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2016, Fuzhou Rockchip Electronics Co., Ltd
+// Copyright (c) 2024 Pengutronix, Oleksij Rempel <[email protected]>
+/*
+ * Based on drivers/power/reset/reboot-mode.c
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/reboot.h>
+#include <linux/pscr.h>
+
+#define PREFIX "pscr-"
+
+struct reason_info {
+ enum power_state_change_reason pscr;
+ u32 magic;
+ struct list_head list;
+};
+
+enum power_state_change_reason system_pscr;
+
+struct pscr_map {
+ const char *reason;
+ enum power_state_change_reason pscr;
+};
+
+struct pscr_map pscr_map_table[] = {
+ { "unknown", PSCR_UNKNOWN },
+ { "under-voltage", PSCR_UNDER_VOLTAGE },
+ { "over-current", PSCR_OVER_CURRENT },
+ { "regulator-failure", PSCR_REGULATOR_FAILURE },
+ { "over-temperature", PSCR_OVERTEMPERATURE },
+};
+
+static int find_reason_by_string(const char *reason)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(pscr_map_table); i++) {
+ if (!strcmp(reason, pscr_map_table[i].reason))
+ return pscr_map_table[i].pscr;
+ }
+
+ return -ENOENT;
+}
+
+/**
+ * set_power_state_change_reason() - Set the system's power state change reason
+ * @reason: The enum value representing the power state change reason
+ *
+ * This function sets the system's power state change reason based on the
+ * provided enum value.
+ */
+void set_power_state_change_reason(enum power_state_change_reason reason)
+{
+ system_pscr = reason;
+}
+EXPORT_SYMBOL_GPL(set_power_state_change_reason);
+
+static unsigned int get_pscr_magic(struct pscr_driver *pscr_drv,
+ const char *cmd)
+{
+ struct reason_info *info;
+
+ list_for_each_entry(info, &pscr_drv->head, list) {
+ if (info->pscr == system_pscr)
+ return info->magic;
+ }
+
+ return 0;
+}
+
+static int pscr_notify(struct notifier_block *this,
+ unsigned long reason, void *cmd)
+{
+ struct pscr_driver *pscr_drv = container_of(this, struct pscr_driver,
+ reboot_notifier);
+ unsigned int magic;
+
+ magic = get_pscr_magic(pscr_drv, cmd);
+ if (magic)
+ pscr_drv->write(pscr_drv, magic);
+
+ return NOTIFY_DONE;
+}
+
+/**
+ * pscr_process_property() - Process a power state change reason property
+ * @pscr_drv: Pointer to the pscr_driver structure
+ * @prop: Pointer to the property structure to be processed
+ *
+ * This function processes a device tree property representing a power state
+ * change reason and initializes the relevant data structures.
+ *
+ * Returns: 0 on success, -ENOMEM on memory allocation failure.
+ */
+static int pscr_process_property(struct pscr_driver *pscr_drv,
+ struct property *prop)
+{
+ struct device *dev = pscr_drv->dev;
+ size_t len = strlen(PREFIX);
+ struct reason_info *info;
+ int ret;
+
+ if (strncmp(prop->name, PREFIX, len))
+ return 0;
+
+ info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ ret = of_property_read_u32(dev->of_node, prop->name, &info->magic);
+ if (ret) {
+ dev_err(dev, "Can't read magic number for %s: %pe\n",
+ prop->name, ERR_PTR(ret));
+ devm_kfree(dev, info);
+ return 0;
+ }
+
+ if (!info->magic) {
+ dev_err(dev, "%s with magic number == 0\n", prop->name);
+ devm_kfree(dev, info);
+ return 0;
+ }
+
+ info->pscr = find_reason_by_string(prop->name + len);
+ if (info->pscr < 0) {
+ dev_err(dev, "unsupported reason name(%s): %pe\n",
+ prop->name, ERR_PTR(info->pscr));
+ devm_kfree(dev, info);
+ return 0;
+ }
+
+ if (info->magic > pscr_drv->max_magic)
+ pscr_drv->max_magic = info->magic;
+
+ dev_dbg(dev, "registering reason = %s, magic = %d, pscr = %d\n",
+ prop->name, info->magic, info->pscr);
+ list_add_tail(&info->list, &pscr_drv->head);
+
+ return 0;
+}
+
+/*
+ * pscr_register() - Register the pscr driver and initialize power state change
+ * reasons
+ * @pscr_drv: Pointer to the pscr_driver structure
+ *
+ * This function registers the pscr driver and initializes power state change
+ * reasons based on device tree properties.
+ *
+ * Returns: 0 on success, -ENOMEM on memory allocation failure
+ */
+int pscr_register(struct pscr_driver *pscr_drv)
+{
+ struct device_node *np = pscr_drv->dev->of_node;
+ struct property *prop;
+
+ INIT_LIST_HEAD(&pscr_drv->head);
+
+ for_each_property_of_node(np, prop) {
+ int ret = pscr_process_property(pscr_drv, prop);
+ if (ret)
+ return ret;
+ }
+
+ pscr_drv->reboot_notifier.notifier_call = pscr_notify;
+ register_reboot_notifier(&pscr_drv->reboot_notifier);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pscr_register);
+
+/*
+ * pscr_unregister() - Unregister the pscr driver's reboot notifier
+ * @pscr_drv: Pointer to the pscr_driver structure
+ *
+ * This function unregisters the reboot notifier for the pscr driver.
+ */
+void pscr_unregister(struct pscr_driver *pscr_drv)
+{
+ unregister_reboot_notifier(&pscr_drv->reboot_notifier);
+}
+EXPORT_SYMBOL_GPL(pscr_unregister);
+
+static void devm_pscr_release(struct device *dev, void *res)
+{
+ pscr_unregister(*(struct pscr_driver **)res);
+}
+
+/**
+ * devm_pscr_register - Register a device-managed PSCR driver
+ * @dev: Device to associate the PSCR driver with
+ * @pscr_drv: Pointer to the PSCR driver to be registered
+ *
+ * Registers a Power State Change Reason (PSCR) driver as a device-managed
+ * resource.
+ *
+ * Returns: 0 on successful registration or a negative error code on failure.
+ */
+int devm_pscr_register(struct device *dev,
+ struct pscr_driver *pscr_drv)
+{
+ struct pscr_driver **dr;
+ int rc;
+
+ dr = devres_alloc(devm_pscr_release, sizeof(*dr), GFP_KERNEL);
+ if (!dr)
+ return -ENOMEM;
+
+ rc = pscr_register(pscr_drv);
+ if (rc) {
+ devres_free(dr);
+ return rc;
+ }
+
+ *dr = pscr_drv;
+ devres_add(dev, dr);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_pscr_register);
+
+static int devm_pscr_match(struct device *dev, void *res, void *data)
+{
+ struct pscr_driver **p = res;
+
+ if (WARN_ON(!p || !*p))
+ return 0;
+
+ return *p == data;
+}
+
+/**
+ * devm_pscr_unregister - Unregister a managed PSCR driver
+ * @dev: Device associated with the PSCR driver
+ * @pscr_drv: Pointer to the PSCR driver to unregister
+ *
+ * Unregisters a device-managed Power State Change Reason (PSCR) driver.
+ * It handles the cleanup and release of resources associated with the PSCR
+ * driver which was previously registered.
+ */
+void devm_pscr_unregister(struct device *dev,
+ struct pscr_driver *pscr_drv)
+{
+ WARN_ON(devres_release(dev,
+ devm_pscr_release,
+ devm_pscr_match, pscr_drv));
+}
+EXPORT_SYMBOL_GPL(devm_pscr_unregister);
+
+MODULE_AUTHOR("Oleksij Rempel <[email protected]>");
+MODULE_DESCRIPTION("Power State Change Reason (PSCR) tracking framework");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/pscr.h b/include/linux/pscr.h
new file mode 100644
index 000000000000..bf66dd69d96d
--- /dev/null
+++ b/include/linux/pscr.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PSCR_H__
+#define __PSCR_H__
+
+enum power_state_change_reason {
+ PSCR_UNKNOWN,
+ PSCR_UNDER_VOLTAGE,
+ PSCR_OVER_CURRENT,
+ PSCR_REGULATOR_FAILURE,
+ PSCR_OVERTEMPERATURE,
+};
+
+struct pscr_driver {
+ struct device *dev;
+ struct list_head head;
+ int (*write)(struct pscr_driver *pscr_drv, u32 magic);
+ struct notifier_block reboot_notifier;
+ u32 max_magic;
+};
+
+int pscr_register(struct pscr_driver *pscr_drv);
+void pscr_unregister(struct pscr_driver *pscr_drv);
+int devm_pscr_register(struct device *dev,
+ struct pscr_driver *pscr_drv);
+void devm_pscr_unregister(struct device *dev,
+ struct pscr_driver *pscr_drv);
+
+
+#if IS_ENABLED(CONFIG_PSCR)
+
+void set_power_state_change_reason(enum power_state_change_reason reason);
+
+#else
+
+static inline void set_power_state_change_reason(enum power_state_change_reason reason)
+{
+}
+#endif
+
+#endif
--
2.39.2
Hi,
On Fri, Jan 19, 2024 at 02:25:14PM +0100, Oleksij Rempel wrote:
> This patch series introduces the Power State Change Reasons (PSCR)
> tracking framework and its related components into the kernel. The PSCR
> framework is designed for systems where traditional methods of storing
> power state change reasons, like PMICs or watchdogs, are inadequate. It
> provides a structured way to store reasons for system shutdowns and
> reboots, such as under-voltage or software-triggered events, in
> non-volatile hardware storage.
>
> These changes are critical for systems requiring detailed postmortem
> analysis and where immediate power-down scenarios limit traditional
> storage options. The framework also assists bootloaders and early-stage
> system components in making informed recovery decisions.
A couple of things come to my mind:
1. Do we need the DT based reason-string-to-integer mapping? Can we
just use a fixed mapping instead? It simplifies the binding a
lot. With that the generic part could be dropped completely.
2. I would expect the infrastructure to read and clear the reason
during boot. If e.g. a watchdog triggers a reset you will otherwise
get an incorrect value.
3. The reason is only stored, but not used? We have a sysfs ABI to
expose the reboot reason to userspace since half a year ago, see
d40befed9a58 (power: reset: at91-reset: add sysfs interface to
the power on reason).
4. Available options should be synced with the list in
include/linux/power/power_on_reason.h
-- Sebastian
Hi,
On Sat, Jan 20, 2024 at 12:19:09AM +0100, Sebastian Reichel wrote:
> Hi,
>
> On Fri, Jan 19, 2024 at 02:25:14PM +0100, Oleksij Rempel wrote:
> > This patch series introduces the Power State Change Reasons (PSCR)
> > tracking framework and its related components into the kernel. The PSCR
> > framework is designed for systems where traditional methods of storing
> > power state change reasons, like PMICs or watchdogs, are inadequate. It
> > provides a structured way to store reasons for system shutdowns and
> > reboots, such as under-voltage or software-triggered events, in
> > non-volatile hardware storage.
> >
> > These changes are critical for systems requiring detailed postmortem
> > analysis and where immediate power-down scenarios limit traditional
> > storage options. The framework also assists bootloaders and early-stage
> > system components in making informed recovery decisions.
>
> A couple of things come to my mind:
>
> 1. Do we need the DT based reason-string-to-integer mapping? Can we
> just use a fixed mapping instead? It simplifies the binding a
> lot. With that the generic part could be dropped completely.
The project I'm working is using RTC for storage. The RTC device in
question provides 8 bits, 3 bits are assigned for PSCR.
Currently all reasons provided in this patch set would fit int to 3 bits,
but soon or later it may expand.
> 2. I would expect the infrastructure to read and clear the reason
> during boot. If e.g. a watchdog triggers a reset you will otherwise
> get an incorrect value.
Hm.. good point. I'll set a value on the boot that there is currently no
attempt to shutdown at all. PSCR works only for software assisted
shutdown/reboot. It should extend, not replace PMIC or watchdog detected
reasons.
> 3. The reason is only stored, but not used? We have a sysfs ABI to
> expose the reboot reason to userspace since half a year ago, see
> d40befed9a58 (power: reset: at91-reset: add sysfs interface to
> the power on reason).
ACK. I'll add sysfs support.
For my use case, the user is the bootloader. The is one of reasons why
DT is used for mappings, this is the stable ABI between this systems.
> 4. Available options should be synced with the list in
> include/linux/power/power_on_reason.h
ACK
Regards,
Oleksij
--
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