gpio: loongson-64bit: Add support for Loongson-2K0300 SoC

This controller's input and output logic is similar to previous
generations of SoCs. Additionally, it's capable of interrupt masking,
and could be configured to detect levels and edges, and is supplied with
a distinct reset signal.

The interrupt functionality is implemented through an irqchip, whose
operations are written with previous generation SoCs in mind and could
be reused. Since all Loongson SoCs with similar interrupt capability
(LS2K1500, LS2K2000) support byte-control mode, these operations are for
byte-control mode only for simplicity.

Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250904013438.2405-3-ziyao@disroot.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: ziyao233

drivers/gpio/Kconfig

@@ -436,6 +436,7 @@ config GPIO_LOONGSON_64BIT
 	depends on LOONGARCH || COMPILE_TEST
 	depends on OF_GPIO
 	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
 	help
 	  Say yes here to support the GPIO functionality of a number of
 	  Loongson series of chips. The Loongson GPIO controller supports

drivers/gpio/gpio-loongson-64bit.c

@@ -7,13 +7,16 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <linux/err.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/generic.h>
 #include <linux/platform_device.h>
 #include <linux/bitops.h>
+#include <linux/reset.h>
 #include <asm/types.h>
 
 enum loongson_gpio_mode {
@@ -28,6 +31,14 @@ struct loongson_gpio_chip_data {
 	unsigned int		out_offset;
 	unsigned int		in_offset;
 	unsigned int		inten_offset;
+	unsigned int		intpol_offset;
+	unsigned int		intedge_offset;
+	unsigned int		intclr_offset;
+	unsigned int		intsts_offset;
+	unsigned int		intdual_offset;
+	unsigned int		intr_num;
+	irq_flow_handler_t	irq_handler;
+	const struct irq_chip	*girqchip;
 };
 
 struct loongson_gpio_chip {
@@ -137,7 +148,140 @@ static int loongson_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
 	return platform_get_irq(pdev, offset);
 }
 
-static int loongson_gpio_init(struct device *dev, struct loongson_gpio_chip *lgpio,
+static void loongson_gpio_irq_ack(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct loongson_gpio_chip *lgpio = to_loongson_gpio_chip(chip);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	writeb(0x1, lgpio->reg_base + lgpio->chip_data->intclr_offset + hwirq);
+}
+
+static void loongson_gpio_irq_mask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct loongson_gpio_chip *lgpio = to_loongson_gpio_chip(chip);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	writeb(0x0, lgpio->reg_base + lgpio->chip_data->inten_offset + hwirq);
+}
+
+static void loongson_gpio_irq_unmask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct loongson_gpio_chip *lgpio = to_loongson_gpio_chip(chip);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	writeb(0x1, lgpio->reg_base + lgpio->chip_data->inten_offset + hwirq);
+}
+
+static int loongson_gpio_irq_set_type(struct irq_data *data, unsigned int type)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct loongson_gpio_chip *lgpio = to_loongson_gpio_chip(chip);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+	u8 pol = 0, edge = 0, dual = 0;
+
+	if ((type & IRQ_TYPE_SENSE_MASK) == IRQ_TYPE_EDGE_BOTH) {
+		edge = 1;
+		dual = 1;
+		irq_set_handler_locked(data, handle_edge_irq);
+	} else {
+		switch (type) {
+		case IRQ_TYPE_LEVEL_HIGH:
+			pol = 1;
+			fallthrough;
+		case IRQ_TYPE_LEVEL_LOW:
+			irq_set_handler_locked(data, handle_level_irq);
+			break;
+
+		case IRQ_TYPE_EDGE_RISING:
+			pol = 1;
+			fallthrough;
+		case IRQ_TYPE_EDGE_FALLING:
+			edge = 1;
+			irq_set_handler_locked(data, handle_edge_irq);
+			break;
+
+		default:
+			return -EINVAL;
+		};
+	}
+
+	writeb(pol, lgpio->reg_base + lgpio->chip_data->intpol_offset + hwirq);
+	writeb(edge, lgpio->reg_base + lgpio->chip_data->intedge_offset + hwirq);
+	writeb(dual, lgpio->reg_base + lgpio->chip_data->intdual_offset + hwirq);
+
+	return 0;
+}
+
+static void loongson_gpio_ls2k0300_irq_handler(struct irq_desc *desc)
+{
+	struct loongson_gpio_chip *lgpio = irq_desc_get_handler_data(desc);
+	struct irq_chip *girqchip = irq_desc_get_chip(desc);
+	int i;
+
+	chained_irq_enter(girqchip, desc);
+
+	for (i = 0; i < lgpio->chip.gc.ngpio; i++) {
+		/*
+		 * For the GPIO controller of LS2K0300, interrupts status bits
+		 * may be wrongly set even if the corresponding interrupt is
+		 * disabled. Thus interrupt enable bits are checked along with
+		 * status bits to detect interrupts reliably.
+		 */
+		if (readb(lgpio->reg_base + lgpio->chip_data->intsts_offset + i) &&
+		    readb(lgpio->reg_base + lgpio->chip_data->inten_offset + i))
+			generic_handle_domain_irq(lgpio->chip.gc.irq.domain, i);
+	}
+
+	chained_irq_exit(girqchip, desc);
+}
+
+static const struct irq_chip loongson_gpio_ls2k0300_irqchip = {
+	.irq_ack	= loongson_gpio_irq_ack,
+	.irq_mask	= loongson_gpio_irq_mask,
+	.irq_unmask	= loongson_gpio_irq_unmask,
+	.irq_set_type	= loongson_gpio_irq_set_type,
+	.flags		= IRQCHIP_IMMUTABLE | IRQCHIP_SKIP_SET_WAKE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+static int loongson_gpio_init_irqchip(struct platform_device *pdev,
+				      struct loongson_gpio_chip *lgpio)
+{
+	const struct loongson_gpio_chip_data *data = lgpio->chip_data;
+	struct gpio_chip *chip = &lgpio->chip.gc;
+	int i;
+
+	chip->irq.default_type = IRQ_TYPE_NONE;
+	chip->irq.handler = handle_bad_irq;
+	chip->irq.parent_handler = data->irq_handler;
+	chip->irq.parent_handler_data = lgpio;
+	gpio_irq_chip_set_chip(&chip->irq, data->girqchip);
+
+	chip->irq.num_parents = data->intr_num;
+	chip->irq.parents = devm_kcalloc(&pdev->dev, data->intr_num,
+					 sizeof(*chip->irq.parents), GFP_KERNEL);
+	if (!chip->parent)
+		return -ENOMEM;
+
+	for (i = 0; i < data->intr_num; i++) {
+		chip->irq.parents[i] = platform_get_irq(pdev, i);
+		if (chip->irq.parents[i] < 0)
+			return dev_err_probe(&pdev->dev, chip->irq.parents[i],
+					     "failed to get IRQ %d\n", i);
+	}
+
+	for (i = 0; i < data->intr_num; i++) {
+		writeb(0x0, lgpio->reg_base + data->inten_offset + i);
+		writeb(0x1, lgpio->reg_base + data->intclr_offset + i);
+	}
+
+	return 0;
+}
+
+static int loongson_gpio_init(struct platform_device *pdev, struct loongson_gpio_chip *lgpio,
 			      void __iomem *reg_base)
 {
 	struct gpio_generic_chip_config config;
@@ -146,7 +290,7 @@ static int loongson_gpio_init(struct device *dev, struct loongson_gpio_chip *lgp
 	lgpio->reg_base = reg_base;
 	if (lgpio->chip_data->mode == BIT_CTRL_MODE) {
 		config = (typeof(config)){
-			.dev = dev,
+			.dev = &pdev->dev,
 			.sz = 8,
 			.dat = lgpio->reg_base + lgpio->chip_data->in_offset,
 			.set = lgpio->reg_base + lgpio->chip_data->out_offset,
@@ -155,7 +299,7 @@ static int loongson_gpio_init(struct device *dev, struct loongson_gpio_chip *lgp
 
 		ret = gpio_generic_chip_init(&lgpio->chip, &config);
 		if (ret) {
-			dev_err(dev, "unable to init generic GPIO\n");
+			dev_err(&pdev->dev, "unable to init generic GPIO\n");
 			return ret;
 		}
 	} else {
@@ -164,23 +308,29 @@ static int loongson_gpio_init(struct device *dev, struct loongson_gpio_chip *lgp
 		lgpio->chip.gc.get_direction = loongson_gpio_get_direction;
 		lgpio->chip.gc.direction_output = loongson_gpio_direction_output;
 		lgpio->chip.gc.set = loongson_gpio_set;
-		lgpio->chip.gc.parent = dev;
+		lgpio->chip.gc.parent = &pdev->dev;
 		spin_lock_init(&lgpio->lock);
 	}
 
 	lgpio->chip.gc.label = lgpio->chip_data->label;
 	lgpio->chip.gc.can_sleep = false;
-	if (lgpio->chip_data->inten_offset)
+	if (lgpio->chip_data->girqchip) {
+		ret = loongson_gpio_init_irqchip(pdev, lgpio);
+		if (ret)
+			return dev_err_probe(&pdev->dev, ret, "failed to initialize irqchip\n");
+	} else if (lgpio->chip_data->inten_offset) {
 		lgpio->chip.gc.to_irq = loongson_gpio_to_irq;
+	}
 
-	return devm_gpiochip_add_data(dev, &lgpio->chip.gc, lgpio);
+	return devm_gpiochip_add_data(&pdev->dev, &lgpio->chip.gc, lgpio);
 }
 
 static int loongson_gpio_probe(struct platform_device *pdev)
 {
 	void __iomem *reg_base;
 	struct loongson_gpio_chip *lgpio;
 	struct device *dev = &pdev->dev;
+	struct reset_control *rst;
 
 	lgpio = devm_kzalloc(dev, sizeof(*lgpio), GFP_KERNEL);
 	if (!lgpio)
@@ -192,7 +342,11 @@ static int loongson_gpio_probe(struct platform_device *pdev)
 	if (IS_ERR(reg_base))
 		return PTR_ERR(reg_base);
 
-	return loongson_gpio_init(dev, lgpio, reg_base);
+	rst = devm_reset_control_get_optional_exclusive_deasserted(&pdev->dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(&pdev->dev, PTR_ERR(rst), "failed to get reset control\n");
+
+	return loongson_gpio_init(pdev, lgpio, reg_base);
 }
 
 static const struct loongson_gpio_chip_data loongson_gpio_ls2k_data = {
@@ -204,6 +358,23 @@ static const struct loongson_gpio_chip_data loongson_gpio_ls2k_data = {
 	.inten_offset = 0x30,
 };
 
+static const struct loongson_gpio_chip_data loongson_gpio_ls2k0300_data = {
+	.label = "ls2k0300_gpio",
+	.mode = BYTE_CTRL_MODE,
+	.conf_offset = 0x800,
+	.in_offset = 0xa00,
+	.out_offset = 0x900,
+	.inten_offset = 0xb00,
+	.intpol_offset = 0xc00,
+	.intedge_offset = 0xd00,
+	.intclr_offset = 0xe00,
+	.intsts_offset = 0xf00,
+	.intdual_offset = 0xf80,
+	.intr_num = 7,
+	.irq_handler = loongson_gpio_ls2k0300_irq_handler,
+	.girqchip = &loongson_gpio_ls2k0300_irqchip,
+};
+
 static const struct loongson_gpio_chip_data loongson_gpio_ls2k0500_data0 = {
 	.label = "ls2k0500_gpio",
 	.mode = BIT_CTRL_MODE,
@@ -300,6 +471,10 @@ static const struct of_device_id loongson_gpio_of_match[] = {
 		.compatible = "loongson,ls2k-gpio",
 		.data = &loongson_gpio_ls2k_data,
 	},
+	{
+		.compatible = "loongson,ls2k0300-gpio",
+		.data = &loongson_gpio_ls2k0300_data,
+	},
 	{
 		.compatible = "loongson,ls2k0500-gpio0",
 		.data = &loongson_gpio_ls2k0500_data0,