Implement the core infrastructure to allow MMC bus types to handle
REGULATOR_EVENT_UNDER_VOLTAGE events from power regulators. This is
primarily aimed at allowing devices like eMMC to perform an emergency
shutdown to prevent data corruption when a power failure is imminent.
This patch introduces:
- A new 'handle_undervoltage' function pointer to 'struct mmc_bus_ops'.
Bus drivers (e.g., for eMMC) can implement this to define their
emergency procedures.
- A workqueue ('uv_work') in 'struct mmc_supply' to handle the event
asynchronously in a high-priority context.
- A new function 'mmc_handle_undervoltage()' which is called from the
workqueue. It stops the host queue to prevent races with card removal,
checks for the bus op, and invokes the handler.
- Functions to register and unregister the regulator notifier, intended
to be called by bus drivers like 'mmc_attach_mmc' when a compatible
card is detected.
The notifier is only registered for the main vmmc supply, as
undervoltage handling for vqmmc or vqmmc2 is not required at this
time.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20250821130751.2089587-2-o.rempel@pengutronix.de
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>
#include "core.h"
#include "card.h"
mmc_card_set_present(card);
+ /*
+ * Register for undervoltage notification if the card supports
+ * power-off notification, enabling emergency shutdowns.
+ */
+ if (mmc_card_mmc(card) &&
+ card->ext_csd.power_off_notification == EXT_CSD_POWER_ON)
+ mmc_regulator_register_undervoltage_notifier(card->host);
+
return 0;
}
{
struct mmc_host *host = card->host;
+ if (mmc_card_present(card))
+ mmc_regulator_unregister_undervoltage_notifier(host);
+
mmc_remove_card_debugfs(card);
if (mmc_card_present(card)) {
mmc_power_up(host, ocr);
}
+/**
+ * mmc_handle_undervoltage - Handle an undervoltage event on the MMC bus
+ * @host: The MMC host that detected the undervoltage condition
+ *
+ * This function is called when an undervoltage event is detected on one of
+ * the MMC regulators.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int mmc_handle_undervoltage(struct mmc_host *host)
+{
+ /* Stop the host to prevent races with card removal */
+ __mmc_stop_host(host);
+
+ if (!host->bus_ops || !host->bus_ops->handle_undervoltage)
+ return 0;
+
+ dev_warn(mmc_dev(host), "%s: Undervoltage detected, initiating emergency stop\n",
+ mmc_hostname(host));
+
+ return host->bus_ops->handle_undervoltage(host);
+}
+
/*
* Assign a mmc bus handler to a host. Only one bus handler may control a
* host at any given time.
int (*sw_reset)(struct mmc_host *);
bool (*cache_enabled)(struct mmc_host *);
int (*flush_cache)(struct mmc_host *);
+ int (*handle_undervoltage)(struct mmc_host *host);
};
void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
void mmc_power_cycle(struct mmc_host *host, u32 ocr);
void mmc_set_initial_state(struct mmc_host *host);
u32 mmc_vddrange_to_ocrmask(int vdd_min, int vdd_max);
+int mmc_handle_undervoltage(struct mmc_host *host);
+void mmc_regulator_register_undervoltage_notifier(struct mmc_host *host);
+void mmc_regulator_unregister_undervoltage_notifier(struct mmc_host *host);
+void mmc_undervoltage_workfn(struct work_struct *work);
static inline void mmc_delay(unsigned int ms)
{
INIT_WORK(&host->sdio_irq_work, sdio_irq_work);
timer_setup(&host->retune_timer, mmc_retune_timer, 0);
+ INIT_WORK(&host->supply.uv_work, mmc_undervoltage_workfn);
+
/*
* By default, hosts do not support SGIO or large requests.
* They have to set these according to their abilities.
#include <linux/err.h>
#include <linux/log2.h>
#include <linux/regulator/consumer.h>
+#include <linux/workqueue.h>
#include <linux/mmc/host.h>
#endif /* CONFIG_REGULATOR */
+/* To be called from a high-priority workqueue */
+void mmc_undervoltage_workfn(struct work_struct *work)
+{
+ struct mmc_supply *supply;
+ struct mmc_host *host;
+
+ supply = container_of(work, struct mmc_supply, uv_work);
+ host = container_of(supply, struct mmc_host, supply);
+
+ mmc_handle_undervoltage(host);
+}
+
+static int mmc_handle_regulator_event(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct mmc_supply *supply = container_of(nb, struct mmc_supply,
+ vmmc_nb);
+ struct mmc_host *host = container_of(supply, struct mmc_host, supply);
+ unsigned long flags;
+
+ switch (event) {
+ case REGULATOR_EVENT_UNDER_VOLTAGE:
+ spin_lock_irqsave(&host->lock, flags);
+ if (host->undervoltage) {
+ spin_unlock_irqrestore(&host->lock, flags);
+ return NOTIFY_OK;
+ }
+
+ host->undervoltage = true;
+ spin_unlock_irqrestore(&host->lock, flags);
+
+ queue_work(system_highpri_wq, &host->supply.uv_work);
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ return NOTIFY_OK;
+}
+
+/**
+ * mmc_regulator_register_undervoltage_notifier - Register for undervoltage
+ * events
+ * @host: MMC host
+ *
+ * To be called by a bus driver when a card supporting graceful shutdown
+ * is attached.
+ */
+void mmc_regulator_register_undervoltage_notifier(struct mmc_host *host)
+{
+ int ret;
+
+ if (IS_ERR_OR_NULL(host->supply.vmmc))
+ return;
+
+ host->supply.vmmc_nb.notifier_call = mmc_handle_regulator_event;
+ ret = regulator_register_notifier(host->supply.vmmc,
+ &host->supply.vmmc_nb);
+ if (ret)
+ dev_warn(mmc_dev(host), "Failed to register vmmc notifier: %d\n", ret);
+}
+
+/**
+ * mmc_regulator_unregister_undervoltage_notifier - Unregister undervoltage
+ * notifier
+ * @host: MMC host
+ */
+void mmc_regulator_unregister_undervoltage_notifier(struct mmc_host *host)
+{
+ if (IS_ERR_OR_NULL(host->supply.vmmc))
+ return;
+
+ regulator_unregister_notifier(host->supply.vmmc, &host->supply.vmmc_nb);
+ cancel_work_sync(&host->supply.uv_work);
+}
+
/**
* mmc_regulator_get_supply - try to get VMMC and VQMMC regulators for a host
* @mmc: the host to regulate
struct regulator;
struct mmc_pwrseq;
+struct notifier_block;
struct mmc_supply {
struct regulator *vmmc; /* Card power supply */
struct regulator *vqmmc; /* Optional Vccq supply */
struct regulator *vqmmc2; /* Optional supply for phy */
+
+ struct notifier_block vmmc_nb; /* Notifier for vmmc */
+ struct work_struct uv_work; /* Undervoltage work */
};
struct mmc_ctx {
unsigned int can_dma_map_merge:1; /* merging can be used */
unsigned int vqmmc_enabled:1; /* vqmmc regulator is enabled */
+ /*
+ * Indicates if an undervoltage event has already been handled.
+ * This prevents repeated regulator notifiers from triggering
+ * multiple REGULATOR_EVENT_UNDER_VOLTAGE events.
+ */
+ unsigned int undervoltage:1; /* Undervoltage state */
+
int rescan_disable; /* disable card detection */
int rescan_entered; /* used with nonremovable devices */
projects / thirdparty / kernel / stable.git / commitdiff
