/*
 * Copyright (c) 2011 Jamie Iles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * All enquiries to support@picochip.com
 */
#include <linux/gpio/driver.h>
/* FIXME: for gpio_get_value(), replace this with direct register read */
#include <linux/gpio.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/platform_data/gpio-dwapb.h>
#include <linux/slab.h>

#define GPIO_SWPORTA_DR		0x00
#define GPIO_SWPORTA_DDR	0x04
#define GPIO_SWPORTB_DR		0x0c
#define GPIO_SWPORTB_DDR	0x10
#define GPIO_SWPORTC_DR		0x18
#define GPIO_SWPORTC_DDR	0x1c
#define GPIO_SWPORTD_DR		0x24
#define GPIO_SWPORTD_DDR	0x28
#define GPIO_INTEN		0x30
#define GPIO_INTMASK		0x34
#define GPIO_INTTYPE_LEVEL	0x38
#define GPIO_INT_POLARITY	0x3c
#define GPIO_INTSTATUS		0x40
#define GPIO_PORTA_DEBOUNCE	0x48
#define GPIO_PORTA_EOI		0x4c
#define GPIO_EXT_PORTA		0x50
#define GPIO_EXT_PORTB		0x54
#define GPIO_EXT_PORTC		0x58
#define GPIO_EXT_PORTD		0x5c

#define DWAPB_MAX_PORTS		4
#define GPIO_EXT_PORT_SIZE	(GPIO_EXT_PORTB - GPIO_EXT_PORTA)
#define GPIO_SWPORT_DR_SIZE	(GPIO_SWPORTB_DR - GPIO_SWPORTA_DR)
#define GPIO_SWPORT_DDR_SIZE	(GPIO_SWPORTB_DDR - GPIO_SWPORTA_DDR)

struct dwapb_gpio;

#ifdef CONFIG_PM_SLEEP
/* Store GPIO context across system-wide suspend/resume transitions */
struct dwapb_context {
	u32 data;
	u32 dir;
	u32 ext;
	u32 int_en;
	u32 int_mask;
	u32 int_type;
	u32 int_pol;
	u32 int_deb;
};
#endif

struct dwapb_gpio_port {
	struct gpio_chip	gc;
	bool			is_registered;
	struct dwapb_gpio	*gpio;
#ifdef CONFIG_PM_SLEEP
	struct dwapb_context	*ctx;
#endif
	unsigned int		idx;
};

struct dwapb_gpio {
	struct	device		*dev;
	void __iomem		*regs;
	struct dwapb_gpio_port	*ports;
	unsigned int		nr_ports;
	struct irq_domain	*domain;
};

static inline u32 dwapb_read(struct dwapb_gpio *gpio, unsigned int offset)
{
	struct gpio_chip *gc	= &gpio->ports[0].gc;
	void __iomem *reg_base	= gpio->regs;

	return gc->read_reg(reg_base + offset);
}

static inline void dwapb_write(struct dwapb_gpio *gpio, unsigned int offset,
			       u32 val)
{
	struct gpio_chip *gc	= &gpio->ports[0].gc;
	void __iomem *reg_base	= gpio->regs;

	gc->write_reg(reg_base + offset, val);
}

static int dwapb_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
{
	struct dwapb_gpio_port *port = gpiochip_get_data(gc);
	struct dwapb_gpio *gpio = port->gpio;

	return irq_find_mapping(gpio->domain, offset);
}

static void dwapb_toggle_trigger(struct dwapb_gpio *gpio, unsigned int offs)
{
	u32 v = dwapb_read(gpio, GPIO_INT_POLARITY);

	if (gpio_get_value(gpio->ports[0].gc.base + offs))
		v &= ~BIT(offs);
	else
		v |= BIT(offs);

	dwapb_write(gpio, GPIO_INT_POLARITY, v);
}

static u32 dwapb_do_irq(struct dwapb_gpio *gpio)
{
	u32 irq_status = readl_relaxed(gpio->regs + GPIO_INTSTATUS);
	u32 ret = irq_status;

	while (irq_status) {
		int hwirq = fls(irq_status) - 1;
		int gpio_irq = irq_find_mapping(gpio->domain, hwirq);

		generic_handle_irq(gpio_irq);
		irq_status &= ~BIT(hwirq);

		if ((irq_get_trigger_type(gpio_irq) & IRQ_TYPE_SENSE_MASK)
			== IRQ_TYPE_EDGE_BOTH)
			dwapb_toggle_trigger(gpio, hwirq);
	}

	return ret;
}

static void dwapb_irq_handler(struct irq_desc *desc)
{
	struct dwapb_gpio *gpio = irq_desc_get_handler_data(desc);
	struct irq_chip *chip = irq_desc_get_chip(desc);

	dwapb_do_irq(gpio);

	if (chip->irq_eoi)
		chip->irq_eoi(irq_desc_get_irq_data(desc));
}

static void dwapb_irq_enable(struct irq_data *d)
{
	struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
	struct dwapb_gpio *gpio = igc->private;
	struct gpio_chip *gc = &gpio->ports[0].gc;
	unsigned long flags;
	u32 val;

	spin_lock_irqsave(&gc->bgpio_lock, flags);
	val = dwapb_read(gpio, GPIO_INTEN);
	val |= BIT(d->hwirq);
	dwapb_write(gpio, GPIO_INTEN, val);
	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
}

static void dwapb_irq_disable(struct irq_data *d)
{
	struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
	struct dwapb_gpio *gpio = igc->private;
	struct gpio_chip *gc = &gpio->ports[0].gc;
	unsigned long flags;
	u32 val;

	spin_lock_irqsave(&gc->bgpio_lock, flags);
	val = dwapb_read(gpio, GPIO_INTEN);
	val &= ~BIT(d->hwirq);
	dwapb_write(gpio, GPIO_INTEN, val);
	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
}

static int dwapb_irq_reqres(struct irq_data *d)
{
	struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
	struct dwapb_gpio *gpio = igc->private;
	struct gpio_chip *gc = &gpio->ports[0].gc;

	if (gpiochip_lock_as_irq(gc, irqd_to_hwirq(d))) {
		dev_err(gpio->dev, "unable to lock HW IRQ %lu for IRQ\n",
			irqd_to_hwirq(d));
		return -EINVAL;
	}
	return 0;
}

static void dwapb_irq_relres(struct irq_data *d)
{
	struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
	struct dwapb_gpio *gpio = igc->private;
	struct gpio_chip *gc = &gpio->ports[0].gc;

	gpiochip_unlock_as_irq(gc, irqd_to_hwirq(d));
}

static int dwapb_irq_set_type(struct irq_data *d, u32 type)
{
	struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
	struct dwapb_gpio *gpio = igc->private;
	struct gpio_chip *gc = &gpio->ports[0].gc;
	int bit = d->hwirq;
	unsigned long level, polarity, flags;

	if (type & ~(IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING |
		     IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW))
		return -EINVAL;

	spin_lock_irqsave(&gc->bgpio_lock, flags);
	level = dwapb_read(gpio, GPIO_INTTYPE_LEVEL);
	polarity = dwapb_read(gpio, GPIO_INT_POLARITY);

	switch (type) {
	case IRQ_TYPE_EDGE_BOTH:
		level |= BIT(bit);
		dwapb_toggle_trigger(gpio, bit);
		break;
	case IRQ_TYPE_EDGE_RISING:
		level |= BIT(bit);
		polarity |= BIT(bit);
		break;
	case IRQ_TYPE_EDGE_FALLING:
		level |= BIT(bit);
		polarity &= ~BIT(bit);
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		level &= ~BIT(bit);
		polarity |= BIT(bit);
		break;
	case IRQ_TYPE_LEVEL_LOW:
		level &= ~BIT(bit);
		polarity &= ~BIT(bit);
		break;
	}

	irq_setup_alt_chip(d, type);

	dwapb_write(gpio, GPIO_INTTYPE_LEVEL, level);
	dwapb_write(gpio, GPIO_INT_POLARITY, polarity);
	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

	return 0;
}

static int dwapb_gpio_set_debounce(struct gpio_chip *gc,
				   unsigned offset, unsigned debounce)
{
	struct dwapb_gpio_port *port = gpiochip_get_data(gc);
	struct dwapb_gpio *gpio = port->gpio;
	unsigned long flags, val_deb;
	unsigned long mask = gc->pin2mask(gc, offset);

	spin_lock_irqsave(&gc->bgpio_lock, flags);

	val_deb = dwapb_read(gpio, GPIO_PORTA_DEBOUNCE);
	if (debounce)
		dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, val_deb | mask);
	else
		dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, val_deb & ~mask);

	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

	return 0;
}

static irqreturn_t dwapb_irq_handler_mfd(int irq, void *dev_id)
{
	u32 worked;
	struct dwapb_gpio *gpio = dev_id;

	worked = dwapb_do_irq(gpio);

	return worked ? IRQ_HANDLED : IRQ_NONE;
}

static void dwapb_configure_irqs(struct dwapb_gpio *gpio,
				 struct dwapb_gpio_port *port,
				 struct dwapb_port_property *pp)
{
	struct gpio_chip *gc = &port->gc;
	struct device_node *node = pp->node;
	struct irq_chip_generic	*irq_gc = NULL;
	unsigned int hwirq, ngpio = gc->ngpio;
	struct irq_chip_type *ct;
	int err, i;

	gpio->domain = irq_domain_add_linear(node, ngpio,
					     &irq_generic_chip_ops, gpio);
	if (!gpio->domain)
		return;

	err = irq_alloc_domain_generic_chips(gpio->domain, ngpio, 2,
					     "gpio-dwapb", handle_level_irq,
					     IRQ_NOREQUEST, 0,
					     IRQ_GC_INIT_NESTED_LOCK);
	if (err) {
		dev_info(gpio->dev, "irq_alloc_domain_generic_chips failed\n");
		irq_domain_remove(gpio->domain);
		gpio->domain = NULL;
		return;
	}

	irq_gc = irq_get_domain_generic_chip(gpio->domain, 0);
	if (!irq_gc) {
		irq_domain_remove(gpio->domain);
		gpio->domain = NULL;
		return;
	}

	irq_gc->reg_base = gpio->regs;
	irq_gc->private = gpio;

	for (i = 0; i < 2; i++) {
		ct = &irq_gc->chip_types[i];
		ct->chip.irq_ack = irq_gc_ack_set_bit;
		ct->chip.irq_mask = irq_gc_mask_set_bit;
		ct->chip.irq_unmask = irq_gc_mask_clr_bit;
		ct->chip.irq_set_type = dwapb_irq_set_type;
		ct->chip.irq_enable = dwapb_irq_enable;
		ct->chip.irq_disable = dwapb_irq_disable;
		ct->chip.irq_request_resources = dwapb_irq_reqres;
		ct->chip.irq_release_resources = dwapb_irq_relres;
		ct->regs.ack = GPIO_PORTA_EOI;
		ct->regs.mask = GPIO_INTMASK;
		ct->type = IRQ_TYPE_LEVEL_MASK;
	}

	irq_gc->chip_types[0].type = IRQ_TYPE_LEVEL_MASK;
	irq_gc->chip_types[1].type = IRQ_TYPE_EDGE_BOTH;
	irq_gc->chip_types[1].handler = handle_edge_irq;

	if (!pp->irq_shared) {
		irq_set_chained_handler_and_data(pp->irq, dwapb_irq_handler,
						 gpio);
	} else {
		/*
		 * Request a shared IRQ since where MFD would have devices
		 * using the same irq pin
		 */
		err = devm_request_irq(gpio->dev, pp->irq,
				       dwapb_irq_handler_mfd,
				       IRQF_SHARED, "gpio-dwapb-mfd", gpio);
		if (err) {
			dev_err(gpio->dev, "error requesting IRQ\n");
			irq_domain_remove(gpio->domain);
			gpio->domain = NULL;
			return;
		}
	}

	for (hwirq = 0 ; hwirq < ngpio ; hwirq++)
		irq_create_mapping(gpio->domain, hwirq);

	port->gc.to_irq = dwapb_gpio_to_irq;
}

static void dwapb_irq_teardown(struct dwapb_gpio *gpio)
{
	struct dwapb_gpio_port *port = &gpio->ports[0];
	struct gpio_chip *gc = &port->gc;
	unsigned int ngpio = gc->ngpio;
	irq_hw_number_t hwirq;

	if (!gpio->domain)
		return;

	for (hwirq = 0 ; hwirq < ngpio ; hwirq++)
		irq_dispose_mapping(irq_find_mapping(gpio->domain, hwirq));

	irq_domain_remove(gpio->domain);
	gpio->domain = NULL;
}

static int dwapb_gpio_add_port(struct dwapb_gpio *gpio,
			       struct dwapb_port_property *pp,
			       unsigned int offs)
{
	struct dwapb_gpio_port *port;
	void __iomem *dat, *set, *dirout;
	int err;

	port = &gpio->ports[offs];
	port->gpio = gpio;
	port->idx = pp->idx;

#ifdef CONFIG_PM_SLEEP
	port->ctx = devm_kzalloc(gpio->dev, sizeof(*port->ctx), GFP_KERNEL);
	if (!port->ctx)
		return -ENOMEM;
#endif

	dat = gpio->regs + GPIO_EXT_PORTA + (pp->idx * GPIO_EXT_PORT_SIZE);
	set = gpio->regs + GPIO_SWPORTA_DR + (pp->idx * GPIO_SWPORT_DR_SIZE);
	dirout = gpio->regs + GPIO_SWPORTA_DDR +
		(pp->idx * GPIO_SWPORT_DDR_SIZE);

	err = bgpio_init(&port->gc, gpio->dev, 4, dat, set, NULL, dirout,
			 NULL, false);
	if (err) {
		dev_err(gpio->dev, "failed to init gpio chip for port%d\n",
			port->idx);
		return err;
	}

#ifdef CONFIG_OF_GPIO
	port->gc.of_node = pp->node;
#endif
	port->gc.ngpio = pp->ngpio;
	port->gc.base = pp->gpio_base;

	/* Only port A support debounce */
	if (pp->idx == 0)
		port->gc.set_debounce = dwapb_gpio_set_debounce;

	if (pp->irq)
		dwapb_configure_irqs(gpio, port, pp);

	err = gpiochip_add_data(&port->gc, port);
	if (err)
		dev_err(gpio->dev, "failed to register gpiochip for port%d\n",
			port->idx);
	else
		port->is_registered = true;

	return err;
}

static void dwapb_gpio_unregister(struct dwapb_gpio *gpio)
{
	unsigned int m;

	for (m = 0; m < gpio->nr_ports; ++m)
		if (gpio->ports[m].is_registered)
			gpiochip_remove(&gpio->ports[m].gc);
}

static struct dwapb_platform_data *
dwapb_gpio_get_pdata_of(struct device *dev)
{
	struct device_node *node, *port_np;
	struct dwapb_platform_data *pdata;
	struct dwapb_port_property *pp;
	int nports;
	int i;

	node = dev->of_node;
	if (!IS_ENABLED(CONFIG_OF_GPIO) || !node)
		return ERR_PTR(-ENODEV);

	nports = of_get_child_count(node);
	if (nports == 0)
		return ERR_PTR(-ENODEV);

	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
		return ERR_PTR(-ENOMEM);

	pdata->properties = devm_kcalloc(dev, nports, sizeof(*pp), GFP_KERNEL);
	if (!pdata->properties)
		return ERR_PTR(-ENOMEM);

	pdata->nports = nports;

	i = 0;
	for_each_child_of_node(node, port_np) {
		pp = &pdata->properties[i++];
		pp->node = port_np;

		if (of_property_read_u32(port_np, "reg", &pp->idx) ||
		    pp->idx >= DWAPB_MAX_PORTS) {
			dev_err(dev,
				"missing/invalid port index for port%d\n", i);
			return ERR_PTR(-EINVAL);
		}

		if (of_property_read_u32(port_np, "snps,nr-gpios",
					 &pp->ngpio)) {
			dev_info(dev,
				 "failed to get number of gpios for port%d\n",
				 i);
			pp->ngpio = 32;
		}

		/*
		 * Only port A can provide interrupts in all configurations of
		 * the IP.
		 */
		if (pp->idx == 0 &&
		    of_property_read_bool(port_np, "interrupt-controller")) {
			pp->irq = irq_of_parse_and_map(port_np, 0);
			if (!pp->irq)
				dev_warn(dev, "no irq for port%d\n", pp->idx);
		}

		pp->irq_shared	= false;
		pp->gpio_base	= -1;
	}

	return pdata;
}

static int dwapb_gpio_probe(struct platform_device *pdev)
{
	unsigned int i;
	struct resource *res;
	struct dwapb_gpio *gpio;
	int err;
	struct device *dev = &pdev->dev;
	struct dwapb_platform_data *pdata = dev_get_platdata(dev);

	if (!pdata) {
		pdata = dwapb_gpio_get_pdata_of(dev);
		if (IS_ERR(pdata))
			return PTR_ERR(pdata);
	}

	if (!pdata->nports)
		return -ENODEV;

	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
	if (!gpio)
		return -ENOMEM;

	gpio->dev = &pdev->dev;
	gpio->nr_ports = pdata->nports;

	gpio->ports = devm_kcalloc(&pdev->dev, gpio->nr_ports,
				   sizeof(*gpio->ports), GFP_KERNEL);
	if (!gpio->ports)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gpio->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(gpio->regs))
		return PTR_ERR(gpio->regs);

	for (i = 0; i < gpio->nr_ports; i++) {
		err = dwapb_gpio_add_port(gpio, &pdata->properties[i], i);
		if (err)
			goto out_unregister;
	}
	platform_set_drvdata(pdev, gpio);

	return 0;

out_unregister:
	dwapb_gpio_unregister(gpio);
	dwapb_irq_teardown(gpio);

	return err;
}

static int dwapb_gpio_remove(struct platform_device *pdev)
{
	struct dwapb_gpio *gpio = platform_get_drvdata(pdev);

	dwapb_gpio_unregister(gpio);
	dwapb_irq_teardown(gpio);

	return 0;
}

static const struct of_device_id dwapb_of_match[] = {
	{ .compatible = "snps,dw-apb-gpio" },
	{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, dwapb_of_match);

#ifdef CONFIG_PM_SLEEP
static int dwapb_gpio_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
	struct gpio_chip *gc	= &gpio->ports[0].gc;
	unsigned long flags;
	int i;

	spin_lock_irqsave(&gc->bgpio_lock, flags);
	for (i = 0; i < gpio->nr_ports; i++) {
		unsigned int offset;
		unsigned int idx = gpio->ports[i].idx;
		struct dwapb_context *ctx = gpio->ports[i].ctx;

		BUG_ON(!ctx);

		offset = GPIO_SWPORTA_DDR + idx * GPIO_SWPORT_DDR_SIZE;
		ctx->dir = dwapb_read(gpio, offset);

		offset = GPIO_SWPORTA_DR + idx * GPIO_SWPORT_DR_SIZE;
		ctx->data = dwapb_read(gpio, offset);

		offset = GPIO_EXT_PORTA + idx * GPIO_EXT_PORT_SIZE;
		ctx->ext = dwapb_read(gpio, offset);

		/* Only port A can provide interrupts */
		if (idx == 0) {
			ctx->int_mask	= dwapb_read(gpio, GPIO_INTMASK);
			ctx->int_en	= dwapb_read(gpio, GPIO_INTEN);
			ctx->int_pol	= dwapb_read(gpio, GPIO_INT_POLARITY);
			ctx->int_type	= dwapb_read(gpio, GPIO_INTTYPE_LEVEL);
			ctx->int_deb	= dwapb_read(gpio, GPIO_PORTA_DEBOUNCE);

			/* Mask out interrupts */
			dwapb_write(gpio, GPIO_INTMASK, 0xffffffff);
		}
	}
	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

	return 0;
}

static int dwapb_gpio_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
	struct gpio_chip *gc	= &gpio->ports[0].gc;
	unsigned long flags;
	int i;

	spin_lock_irqsave(&gc->bgpio_lock, flags);
	for (i = 0; i < gpio->nr_ports; i++) {
		unsigned int offset;
		unsigned int idx = gpio->ports[i].idx;
		struct dwapb_context *ctx = gpio->ports[i].ctx;

		BUG_ON(!ctx);

		offset = GPIO_SWPORTA_DR + idx * GPIO_SWPORT_DR_SIZE;
		dwapb_write(gpio, offset, ctx->data);

		offset = GPIO_SWPORTA_DDR + idx * GPIO_SWPORT_DDR_SIZE;
		dwapb_write(gpio, offset, ctx->dir);

		offset = GPIO_EXT_PORTA + idx * GPIO_EXT_PORT_SIZE;
		dwapb_write(gpio, offset, ctx->ext);

		/* Only port A can provide interrupts */
		if (idx == 0) {
			dwapb_write(gpio, GPIO_INTTYPE_LEVEL, ctx->int_type);
			dwapb_write(gpio, GPIO_INT_POLARITY, ctx->int_pol);
			dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, ctx->int_deb);
			dwapb_write(gpio, GPIO_INTEN, ctx->int_en);
			dwapb_write(gpio, GPIO_INTMASK, ctx->int_mask);

			/* Clear out spurious interrupts */
			dwapb_write(gpio, GPIO_PORTA_EOI, 0xffffffff);
		}
	}
	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(dwapb_gpio_pm_ops, dwapb_gpio_suspend,
			 dwapb_gpio_resume);

static struct platform_driver dwapb_gpio_driver = {
	.driver		= {
		.name	= "gpio-dwapb",
		.pm	= &dwapb_gpio_pm_ops,
		.of_match_table = of_match_ptr(dwapb_of_match),
	},
	.probe		= dwapb_gpio_probe,
	.remove		= dwapb_gpio_remove,
};

module_platform_driver(dwapb_gpio_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver");