[PATCH 3/3] power: reset: add new gs101-poweroff driver

[Alexey Klimov <alexey.klimov@linaro.org>]

The driver allows switching off the Google gs101 SoC (Pixel6 family of
mobile phones). The syscon-poweroff cannot be used since gs101 requires
smc-based regmap i.e. a write to PMU register done from EL3 is required.
Additionally the power off write should be performed when power button
is not pressed.

When USB charging cable is connected then this leads to a reboot of
a device initiated by bootloader/firmware.

Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
---
 drivers/power/reset/Kconfig          |   7 ++
 drivers/power/reset/Makefile         |   1 +
 drivers/power/reset/gs101-poweroff.c | 157 +++++++++++++++++++++++++++
 3 files changed, 165 insertions(+)
 create mode 100644 drivers/power/reset/gs101-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index fece990af4a7..e7323b3b4a61 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -100,6 +100,13 @@ config POWER_RESET_GPIO_RESTART
 	  If your board needs a GPIO high/low to restart, say Y and
 	  create a binding in your devicetree.
 
+config POWER_RESET_GS101_POWEROFF
+	tristate "GS101 power-off driver"
+	depends on ARCH_EXYNOS || COMPILE_TEST
+	help
+	  This driver supports turning off the Google Tensor Pixel6 GS101 phones.
+	  Select this if you're building a kernel with Google Tensor SoC support.
+
 config POWER_RESET_HISI
 	bool "Hisilicon power-off driver"
 	depends on ARCH_HISI
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index a95d1bd275d1..7065b7e4ce77 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
 obj-$(CONFIG_POWER_RESET_GEMINI_POWEROFF) += gemini-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
+obj-$(CONFIG_POWER_RESET_GS101_POWEROFF) += gs101-poweroff.o
 obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
 obj-$(CONFIG_POWER_RESET_LINKSTATION) += linkstation-poweroff.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
diff --git a/drivers/power/reset/gs101-poweroff.c b/drivers/power/reset/gs101-poweroff.c
new file mode 100644
index 000000000000..2be903de16a1
--- /dev/null
+++ b/drivers/power/reset/gs101-poweroff.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GS101 Poweroff Driver
+ *
+ * Copyright (c) 2024, Linaro Ltd.
+ * Author: Alexey Klimov <alexey.klimov@linaro.org>
+ */
+
+#include <linux/delay.h>
+#include <linux/devm-helpers.h>
+#include <linux/input.h>
+#include <linux/io.h>
+#include <linux/keyboard.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/soc/samsung/exynos-pmu.h>
+
+#define shwork_to_poweroff(x)		\
+	container_of(x, struct gs101_poweroff, shutdown_work)
+
+#define keyboard_nb_to_poweroff(x)	\
+	container_of(x, struct gs101_poweroff, keyboard_nb)
+
+struct gs101_poweroff {
+	struct notifier_block keyboard_nb;
+	bool power_key_pressed;
+	struct work_struct shutdown_work;
+	struct regmap *map;
+	u32 offset;
+	u32 mask;
+};
+
+static struct gs101_poweroff *gs101_poweroff_ctx;
+
+static void gs101_shutdown_work_fn(struct work_struct *work)
+{
+	struct gs101_poweroff *gs101 = shwork_to_poweroff(work);
+
+	while (1) {
+		/* wait for power button release */
+		if (!gs101->power_key_pressed) {
+			/* Issue the poweroff */
+			regmap_update_bits(gs101->map,
+					   gs101->offset,
+					   gs101->mask, 0);
+		} else {
+			/*
+			 * if power button is not released,
+			 * wait and check TA again
+			 */
+			pr_info("power key is not released.\n");
+		}
+		mdelay(1000);
+	}
+}
+
+static int gs101_keyboard_notifier_call(struct notifier_block *nb,
+					unsigned long code, void *_param)
+{
+	struct keyboard_notifier_param *param = _param;
+
+	if (param->value == KEY_POWER) {
+		struct gs101_poweroff *gs101 = keyboard_nb_to_poweroff(nb);
+
+		gs101->power_key_pressed = param->down;
+	}
+
+	return NOTIFY_OK;
+}
+
+static void gs101_poweroff(void)
+{
+	schedule_work(&gs101_poweroff_ctx->shutdown_work);
+}
+
+static int gs101_poweroff_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gs101_poweroff *gs101;
+	int ret;
+
+	gs101 = devm_kzalloc(dev, sizeof(*gs101), GFP_KERNEL);
+	if (!gs101)
+		return -ENOMEM;
+
+	gs101->map = exynos_get_pmu_regmap_by_phandle(dev->of_node,
+						      "samsung,syscon-phandle");
+	if (IS_ERR(gs101->map))
+		return PTR_ERR(gs101->map);
+
+	if (of_property_read_u32(dev->of_node, "offset", &gs101->offset)) {
+		dev_err(dev, "unable to read 'offset' from DT\n");
+		return -EINVAL;
+	}
+
+	if (of_property_read_u32(dev->of_node, "mask", &gs101->mask)) {
+		dev_err(dev, "unable to read 'mask' from DT\n");
+		return -EINVAL;
+	}
+
+	gs101->keyboard_nb.notifier_call = gs101_keyboard_notifier_call;
+	ret = register_keyboard_notifier(&gs101->keyboard_nb);
+	if (ret) {
+		dev_err(dev, "failed to register keyboard notifier: %i\n", ret);
+		return ret;
+	}
+
+	ret = devm_work_autocancel(dev, &gs101->shutdown_work,
+				   gs101_shutdown_work_fn);
+	if (ret) {
+		dev_err(dev, "failed to register gs101 shutdown_work: %i\n", ret);
+		unregister_keyboard_notifier(&gs101->keyboard_nb);
+		return ret;
+	}
+
+	gs101_poweroff_ctx = gs101;
+	platform_set_drvdata(pdev, gs101);
+
+	/*
+	 * At this point there is a chance that psci_sys_poweroff already
+	 * registered as pm_power_off hook but unfortunately it cannot power
+	 * off the gs101 SoC hence we are rewriting it here just as is.
+	 */
+	pm_power_off = gs101_poweroff;
+
+	return 0;
+}
+
+static void gs101_poweroff_remove(struct platform_device *pdev)
+{
+	struct gs101_poweroff *gs101 = platform_get_drvdata(pdev);
+
+	if (pm_power_off == gs101_poweroff)
+		pm_power_off = NULL;
+
+	unregister_keyboard_notifier(&gs101->keyboard_nb);
+}
+
+static const struct of_device_id gs101_poweroff_of_match[] = {
+	{ .compatible = "google,gs101-poweroff" },
+	{}
+};
+
+static struct platform_driver gs101_poweroff_driver = {
+	.probe = gs101_poweroff_probe,
+	.remove_new = gs101_poweroff_remove,
+	.driver = {
+		.name = "gs101-poweroff",
+		.of_match_table = gs101_poweroff_of_match,
+	},
+};
+
+module_platform_driver(gs101_poweroff_driver);
+MODULE_AUTHOR("Alexey Klimov <alexey.klimov@linaro.org>");
+MODULE_DESCRIPTION("Google GS101 poweroff driver");
+MODULE_LICENSE("GPL v2");
-- 
2.43.0