power: reset: pwr-mlxbf: add BlueField SoC power control driver

This driver supports handling 2 BlueField power states controlled by
GPIO interrupts:

1) chip reset and
2) low power mode
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/reset/Kconfig

@@ -297,4 +297,10 @@ config NVMEM_REBOOT_MODE
 	  then the bootloader can read it and take different
 	  action according to the mode.
 
+config POWER_MLXBF
+	tristate "Mellanox BlueField power handling driver"
+	depends on (GPIO_MLXBF2 && ACPI)
+	help
+	  This driver supports reset or low power mode handling for Mellanox BlueField.
+
 endif

drivers/power/reset/Makefile

@@ -35,3 +35,4 @@ obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
 obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
 obj-$(CONFIG_POWER_RESET_SC27XX) += sc27xx-poweroff.o
 obj-$(CONFIG_NVMEM_REBOOT_MODE) += nvmem-reboot-mode.o
+obj-$(CONFIG_POWER_MLXBF) += pwr-mlxbf.o

drivers/power/reset/pwr-mlxbf.c

+// SPDX-License-Identifier: GPL-2.0-only or BSD-3-Clause
+
+/*
+ *  Copyright (c) 2022 NVIDIA CORPORATION & AFFILIATES.
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/reboot.h>
+#include <linux/types.h>
+
+const char *rst_pwr_hid = "MLNXBF24";
+const char *low_pwr_hid = "MLNXBF29";
+
+struct pwr_mlxbf {
+	struct work_struct send_work;
+	const char *hid;
+};
+
+static void pwr_mlxbf_send_work(struct work_struct *work)
+{
+	acpi_bus_generate_netlink_event("button/power.*", "Power Button", 0x80, 1);
+}
+
+static irqreturn_t pwr_mlxbf_irq(int irq, void *ptr)
+{
+	struct pwr_mlxbf *priv = ptr;
+
+	if (!strncmp(priv->hid, rst_pwr_hid, 8))
+		emergency_restart();
+
+	if (!strncmp(priv->hid, low_pwr_hid, 8))
+		schedule_work(&priv->send_work);
+
+	return IRQ_HANDLED;
+}
+
+static int pwr_mlxbf_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct acpi_device *adev;
+	struct pwr_mlxbf *priv;
+	const char *hid;
+	int irq, err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	adev = ACPI_COMPANION(dev);
+	if (!adev)
+		return -ENXIO;
+
+	hid = acpi_device_hid(adev);
+	priv->hid = hid;
+
+	irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Error getting %s irq.\n", priv->hid);
+
+	err = devm_work_autocancel(dev, &priv->send_work, pwr_mlxbf_send_work);
+	if (err)
+		return err;
+
+	err = devm_request_irq(dev, irq, pwr_mlxbf_irq, 0, hid, priv);
+	if (err)
+		dev_err(dev, "Failed request of %s irq\n", priv->hid);
+
+	return err;
+}
+
+static const struct acpi_device_id __maybe_unused pwr_mlxbf_acpi_match[] = {
+	{ "MLNXBF24", 0 },
+	{ "MLNXBF29", 0 },
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, pwr_mlxbf_acpi_match);
+
+static struct platform_driver pwr_mlxbf_driver = {
+	.driver = {
+		.name = "pwr_mlxbf",
+		.acpi_match_table = pwr_mlxbf_acpi_match,
+	},
+	.probe    = pwr_mlxbf_probe,
+};
+
+module_platform_driver(pwr_mlxbf_driver);
+
+MODULE_DESCRIPTION("Mellanox BlueField power driver");
+MODULE_AUTHOR("Asmaa Mnebhi <asmaa@nvidia.com>");
+MODULE_LICENSE("Dual BSD/GPL");