This driver implements the shutdown function of Photonicat PMU:

- Host notifies PMU to shutdown:
  When powering off, a shutdown command (0x0F) needs to be sent
  to the MCU.

- PMU notifies host to shutdown:
  If the power button is long pressed, the MCU will send a shutdown
  command (0x0D) to the system.
  If system does not shutdown within 60 seconds,
  the power will be turned off directly.

Signed-off-by: Junhao Xie <redacted>
---
 drivers/power/reset/Kconfig               | 12 +++
 drivers/power/reset/Makefile              |  1 +
 drivers/power/reset/photonicat-poweroff.c | 95 +++++++++++++++++++++++
 3 files changed, 108 insertions(+)
 create mode 100644 drivers/power/reset/photonicat-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index fece990af4a7..c59529ce25a2 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig

@@ -148,6 +148,18 @@ config POWER_RESET_ODROID_GO_ULTRA_POWEROFF
 	help
 	  This driver supports Power off for Odroid Go Ultra device.
 
+config POWER_RESET_PHOTONICAT_POWEROFF
+	tristate "Photonicat PMU power-off driver"
+	depends on MFD_PHOTONICAT_PMU

+	help
+	  This driver supports Power off for Photonicat PMU device.
+
+	  Supports operations:
+	    Host notifies PMU to shutdown
+	    PMU notifies host to shutdown
+
+	  Say Y if you have a Photonicat board.
+
 config POWER_RESET_PIIX4_POWEROFF
 	tristate "Intel PIIX4 power-off driver"
 	depends on PCI

diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index a95d1bd275d1..339b36812b95 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile

@@ -17,6 +17,7 @@ obj-$(CONFIG_POWER_RESET_MT6323) += mt6323-poweroff.o
 obj-$(CONFIG_POWER_RESET_QCOM_PON) += qcom-pon.o
 obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
 obj-$(CONFIG_POWER_RESET_ODROID_GO_ULTRA_POWEROFF) += odroid-go-ultra-poweroff.o
+obj-$(CONFIG_POWER_RESET_PHOTONICAT_POWEROFF) += photonicat-poweroff.o
 obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o

diff --git a/drivers/power/reset/photonicat-poweroff.c b/drivers/power/reset/photonicat-poweroff.c
new file mode 100644
index 000000000000..f9f1ea179247
--- /dev/null
+++ b/drivers/power/reset/photonicat-poweroff.c

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024 Junhao Xie <bigfoot@classfun.cn>
+ */
+
+#include <linux/mfd/photonicat-pmu.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+struct pcat_poweroff {
+	struct device *dev;
+	struct pcat_pmu *pmu;
+	struct notifier_block nb;
+};
+
+static int pcat_do_poweroff(struct sys_off_data *data)
+{
+	struct pcat_poweroff *poweroff = data->cb_data;
+
+	dev_info(poweroff->dev, "Host request PMU shutdown\n");
+	pcat_pmu_write_data(poweroff->pmu, PCAT_CMD_HOST_REQUEST_SHUTDOWN,
+			    NULL, 0);
+
+	return NOTIFY_DONE;
+}
+
+static int pcat_poweroff_notify(struct notifier_block *nb, unsigned long action,
+				void *data)
+{
+	struct pcat_poweroff *poweroff =
+		container_of(nb, struct pcat_poweroff, nb);
+
+	if (action != PCAT_CMD_PMU_REQUEST_SHUTDOWN)
+		return NOTIFY_DONE;
+
+	dev_info(poweroff->dev, "PMU request host shutdown\n");