soc: loongson2_pm: add power management support

The Loongson-2's power management controller was ACPI, supports ACPI
S2Idle (Suspend To Idle), ACPI S3 (Suspend To RAM), ACPI S4 (Suspend To
Disk), ACPI S5 (Soft Shutdown) and supports multiple wake-up methods
(USB, GMAC, PWRBTN, etc.). This driver was to add power management
controller support that base on dts for Loongson-2 series SoCs.

Co-developed-by: Liu Yun <liuyun@loongson.cn>
Signed-off-by: Liu Yun <liuyun@loongson.cn>
Co-developed-by: Liu Peibao <liupeibao@loongson.cn>
Signed-off-by: Liu Peibao <liupeibao@loongson.cn>
Cc: soc@kernel.org
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
Link: https://lore.kernel.org/r/20230803063703.5659-3-zhuyinbo@loongson.cn
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

MAINTAINERS

@@ -12287,6 +12287,7 @@ M:	Yinbo Zhu <zhuyinbo@loongson.cn>
 L:	linux-pm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/soc/loongson/loongson,ls2k-pmc.yaml
+F:	drivers/soc/loongson/loongson2_pm.c
 
 LOONGSON-2 SOC SERIES PINCTRL DRIVER
 M:	zhanghongchen <zhanghongchen@loongson.cn>

drivers/soc/loongson/Kconfig

@@ -16,3 +16,13 @@ config LOONGSON2_GUTS
 	 SoCs. Initially only reading SVR and registering soc device are
 	 supported. Other guts accesses, such as reading firmware configuration
 	 by default, should eventually be added into this driver as well.
+
+config LOONGSON2_PM
+	bool "Loongson-2 SoC Power Management Controller Driver"
+	depends on LOONGARCH && OF
+	help
+	  The Loongson-2's power management controller was ACPI, supports ACPI
+	  S2Idle (Suspend To Idle), ACPI S3 (Suspend To RAM), ACPI S4 (Suspend To
+	  Disk), ACPI S5 (Soft Shutdown) and supports multiple wake-up methods
+	  (USB, GMAC, PWRBTN, etc.). This driver was to add power management
+	  controller support that base on dts for Loongson-2 series SoCs.

drivers/soc/loongson/Makefile

@@ -4,3 +4,4 @@
 #
 
 obj-$(CONFIG_LOONGSON2_GUTS)		+= loongson2_guts.o
+obj-$(CONFIG_LOONGSON2_PM)		+= loongson2_pm.o

drivers/soc/loongson/loongson2_pm.c

@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Loongson-2 PM Support
+ *
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/suspend.h>
+#include <linux/interrupt.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/platform_device.h>
+#include <asm/bootinfo.h>
+#include <asm/suspend.h>
+
+#define LOONGSON2_PM1_CNT_REG		0x14
+#define LOONGSON2_PM1_STS_REG		0x0c
+#define LOONGSON2_PM1_ENA_REG		0x10
+#define LOONGSON2_GPE0_STS_REG		0x28
+#define LOONGSON2_GPE0_ENA_REG		0x2c
+
+#define LOONGSON2_PM1_PWRBTN_STS	BIT(8)
+#define LOONGSON2_PM1_PCIEXP_WAKE_STS	BIT(14)
+#define LOONGSON2_PM1_WAKE_STS		BIT(15)
+#define LOONGSON2_PM1_CNT_INT_EN	BIT(0)
+#define LOONGSON2_PM1_PWRBTN_EN		LOONGSON2_PM1_PWRBTN_STS
+
+static struct loongson2_pm {
+	void __iomem			*base;
+	struct input_dev		*dev;
+	bool				suspended;
+} loongson2_pm;
+
+#define loongson2_pm_readw(reg)		readw(loongson2_pm.base + reg)
+#define loongson2_pm_readl(reg)		readl(loongson2_pm.base + reg)
+#define loongson2_pm_writew(val, reg)	writew(val, loongson2_pm.base + reg)
+#define loongson2_pm_writel(val, reg)	writel(val, loongson2_pm.base + reg)
+
+static void loongson2_pm_status_clear(void)
+{
+	u16 value;
+
+	value = loongson2_pm_readw(LOONGSON2_PM1_STS_REG);
+	value |= (LOONGSON2_PM1_PWRBTN_STS | LOONGSON2_PM1_PCIEXP_WAKE_STS |
+		  LOONGSON2_PM1_WAKE_STS);
+	loongson2_pm_writew(value, LOONGSON2_PM1_STS_REG);
+	loongson2_pm_writel(loongson2_pm_readl(LOONGSON2_GPE0_STS_REG), LOONGSON2_GPE0_STS_REG);
+}
+
+static void loongson2_pm_irq_enable(void)
+{
+	u16 value;
+
+	value = loongson2_pm_readw(LOONGSON2_PM1_CNT_REG);
+	value |= LOONGSON2_PM1_CNT_INT_EN;
+	loongson2_pm_writew(value, LOONGSON2_PM1_CNT_REG);
+
+	value = loongson2_pm_readw(LOONGSON2_PM1_ENA_REG);
+	value |= LOONGSON2_PM1_PWRBTN_EN;
+	loongson2_pm_writew(value, LOONGSON2_PM1_ENA_REG);
+}
+
+static int loongson2_suspend_enter(suspend_state_t state)
+{
+	loongson2_pm_status_clear();
+	loongarch_common_suspend();
+	loongarch_suspend_enter();
+	loongarch_common_resume();
+	loongson2_pm_irq_enable();
+	pm_set_resume_via_firmware();
+
+	return 0;
+}
+
+static int loongson2_suspend_begin(suspend_state_t state)
+{
+	pm_set_suspend_via_firmware();
+
+	return 0;
+}
+
+static int loongson2_suspend_valid_state(suspend_state_t state)
+{
+	return (state == PM_SUSPEND_MEM);
+}
+
+static const struct platform_suspend_ops loongson2_suspend_ops = {
+	.valid	= loongson2_suspend_valid_state,
+	.begin	= loongson2_suspend_begin,
+	.enter	= loongson2_suspend_enter,
+};
+
+static int loongson2_power_button_init(struct device *dev, int irq)
+{
+	int ret;
+	struct input_dev *button;
+
+	button = input_allocate_device();
+	if (!dev)
+		return -ENOMEM;
+
+	button->name = "Power Button";
+	button->phys = "pm/button/input0";
+	button->id.bustype = BUS_HOST;
+	button->dev.parent = NULL;
+	input_set_capability(button, EV_KEY, KEY_POWER);
+
+	ret = input_register_device(button);
+	if (ret)
+		goto free_dev;
+
+	dev_pm_set_wake_irq(&button->dev, irq);
+	device_set_wakeup_capable(&button->dev, true);
+	device_set_wakeup_enable(&button->dev, true);
+
+	loongson2_pm.dev = button;
+	dev_info(dev, "Power Button: Init successful!\n");
+
+	return 0;
+
+free_dev:
+	input_free_device(button);
+
+	return ret;
+}
+
+static irqreturn_t loongson2_pm_irq_handler(int irq, void *dev_id)
+{
+	u16 status = loongson2_pm_readw(LOONGSON2_PM1_STS_REG);
+
+	if (!loongson2_pm.suspended && (status & LOONGSON2_PM1_PWRBTN_STS)) {
+		pr_info("Power Button pressed...\n");
+		input_report_key(loongson2_pm.dev, KEY_POWER, 1);
+		input_sync(loongson2_pm.dev);
+		input_report_key(loongson2_pm.dev, KEY_POWER, 0);
+		input_sync(loongson2_pm.dev);
+	}
+
+	loongson2_pm_status_clear();
+
+	return IRQ_HANDLED;
+}
+
+static int __maybe_unused loongson2_pm_suspend(struct device *dev)
+{
+	loongson2_pm.suspended = true;
+
+	return 0;
+}
+
+static int __maybe_unused loongson2_pm_resume(struct device *dev)
+{
+	loongson2_pm.suspended = false;
+
+	return 0;
+}
+static SIMPLE_DEV_PM_OPS(loongson2_pm_ops, loongson2_pm_suspend, loongson2_pm_resume);
+
+static int loongson2_pm_probe(struct platform_device *pdev)
+{
+	int irq, retval;
+	u64 suspend_addr;
+	struct device *dev = &pdev->dev;
+
+	loongson2_pm.base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(loongson2_pm.base))
+		return PTR_ERR(loongson2_pm.base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	if (!device_property_read_u64(dev, "loongson,suspend-address", &suspend_addr))
+		loongson_sysconf.suspend_addr = (u64)phys_to_virt(suspend_addr);
+	else
+		dev_err(dev, "No loongson,suspend-address, could not support S3!\n");
+
+	if (loongson2_power_button_init(dev, irq))
+		return -EINVAL;
+
+	retval = devm_request_irq(&pdev->dev, irq, loongson2_pm_irq_handler,
+				  IRQF_SHARED, "pm_irq", &loongson2_pm);
+	if (retval)
+		return retval;
+
+	loongson2_pm_irq_enable();
+	loongson2_pm_status_clear();
+
+	if (loongson_sysconf.suspend_addr)
+		suspend_set_ops(&loongson2_suspend_ops);
+
+	return 0;
+}
+
+static const struct of_device_id loongson2_pm_match[] = {
+	{ .compatible = "loongson,ls2k0500-pmc", },
+	{ .compatible = "loongson,ls2k1000-pmc", },
+	{},
+};
+
+static struct platform_driver loongson2_pm_driver = {
+	.driver = {
+		.name = "ls2k-pm",
+		.pm = &loongson2_pm_ops,
+		.of_match_table = loongson2_pm_match,
+	},
+	.probe = loongson2_pm_probe,
+};
+module_platform_driver(loongson2_pm_driver);
+
+MODULE_DESCRIPTION("Loongson-2 PM driver");
+MODULE_LICENSE("GPL");