power: reset: Add qcom reboot reason driver

Add support for setting reboot reason on Qualcomm boards. This driver
uses reboot notifier chain to support commands such as "reboot
bootloader" to boot board to fastboot mode.

Change-Id: I3ccaa926dc92df9d0acd4261c79ff7f3c9e1c438
Signed-off-by: Elliot Berman <eberman@codeaurora.org>

drivers/power/reset/Kconfig

@@ -135,6 +135,15 @@ config POWER_RESET_QCOM_PON
 	  power-on and reboot reason, Say Y.
 	  If unsure, Say N.
 
+config POWER_RESET_QCOM_REBOOT_REASON
+	tristate "MSM reboot mode driver"
+	depends on ARCH_QCOM
+	help
+	  Support for setting reboot reason on MSM boards.
+	  This feature supports commands such as "reboot bootloader"
+	  to boot the MSM board to fastboot mode.
+	  If unsure, say Y.
+
 config POWER_RESET_OCELOT_RESET
 	bool "Microsemi Ocelot reset driver"
 	depends on MSCC_OCELOT || COMPILE_TEST

drivers/power/reset/Makefile

@@ -13,6 +13,7 @@ obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
 obj-$(CONFIG_POWER_RESET_QCOM_DOWNLOAD_MODE) += qcom-dload-mode.o
 obj-$(CONFIG_POWER_RESET_QCOM_PON) += qcom-pon.o
+obj-$(CONFIG_POWER_RESET_QCOM_REBOOT_REASON) += qcom-reboot-reason.o
 obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
 obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o

drivers/power/reset/qcom-reboot-reason.c

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2019 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/pm.h>
+#include <linux/of_address.h>
+#include <linux/nvmem-consumer.h>
+
+struct qcom_reboot_reason {
+	struct device *dev;
+	struct notifier_block reboot_nb;
+	struct nvmem_cell *nvmem_cell;
+};
+
+struct poweroff_reason {
+	const char *cmd;
+	unsigned char pon_reason;
+};
+
+static struct poweroff_reason reasons[] = {
+	{ "recovery",			0x01 },
+	{ "bootloader",			0x02 },
+	{ "rtc",			0x03 },
+	{ "dm-verity device corrupted",	0x04 },
+	{ "dm-verity enforcing",	0x05 },
+	{ "keys clear",			0x06 },
+	{}
+};
+
+static int qcom_reboot_reason_reboot(struct notifier_block *this,
+				     unsigned long event, void *ptr)
+{
+	char *cmd = ptr;
+	struct qcom_reboot_reason *reboot = container_of(this,
+		struct qcom_reboot_reason, reboot_nb);
+	struct poweroff_reason *reason;
+
+	if (!cmd)
+		return NOTIFY_OK;
+	for (reason = reasons; reason->cmd; reason++) {
+		if (!strcmp(cmd, reason->cmd)) {
+			nvmem_cell_write(reboot->nvmem_cell,
+					 &reason->pon_reason,
+					 sizeof(reason->pon_reason));
+			break;
+		}
+	}
+
+	return NOTIFY_OK;
+}
+
+static int qcom_reboot_reason_probe(struct platform_device *pdev)
+{
+	struct qcom_reboot_reason *reboot;
+
+	reboot = devm_kzalloc(&pdev->dev, sizeof(*reboot), GFP_KERNEL);
+	if (!reboot)
+		return -ENOMEM;
+
+	reboot->dev = &pdev->dev;
+
+	reboot->nvmem_cell = nvmem_cell_get(reboot->dev, "restart_reason");
+
+	if (IS_ERR(reboot->nvmem_cell))
+		return PTR_ERR(reboot->nvmem_cell);
+
+	reboot->reboot_nb.notifier_call = qcom_reboot_reason_reboot;
+	reboot->reboot_nb.priority = 255;
+	register_reboot_notifier(&reboot->reboot_nb);
+
+	platform_set_drvdata(pdev, reboot);
+
+	return 0;
+}
+
+static int qcom_reboot_reason_remove(struct platform_device *pdev)
+{
+	struct qcom_reboot_reason *reboot = platform_get_drvdata(pdev);
+
+	unregister_reboot_notifier(&reboot->reboot_nb);
+
+	return 0;
+}
+
+static const struct of_device_id of_qcom_reboot_reason_match[] = {
+	{ .compatible = "qcom,reboot-reason", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_qcom_reboot_reason_match);
+
+static struct platform_driver qcom_reboot_reason_driver = {
+	.probe = qcom_reboot_reason_probe,
+	.remove = qcom_reboot_reason_remove,
+	.driver = {
+		.name = "qcom-reboot-reason",
+		.of_match_table = of_match_ptr(of_qcom_reboot_reason_match),
+	},
+};
+
+module_platform_driver(qcom_reboot_reason_driver);
+
+MODULE_DESCRIPTION("MSM Reboot Reason Driver");
+MODULE_LICENSE("GPL v2");