// SPDX-License-Identifier: GPL-2.0
/*
 * Nuvoton NPCM Serial GPIO Driver
 *
 * Copyright (C) 2021 Nuvoton Technologies
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/gpio/driver.h>
#include <linux/hashtable.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/units.h>

#define MAX_NR_HW_SGPIO		64

#define  NPCM_IOXCFG1		0x2A
#define  NPCM_IOXCFG1_SFT_CLK	GENMASK(3, 0)
#define  NPCM_IOXCFG1_SCLK_POL	BIT(4)
#define  NPCM_IOXCFG1_LDSH_POL	BIT(5)

#define  NPCM_IOXCTS			0x28
#define  NPCM_IOXCTS_IOXIF_EN		BIT(7)
#define  NPCM_IOXCTS_RD_MODE		GENMASK(2, 1)
#define  NPCM_IOXCTS_RD_MODE_PERIODIC	BIT(2)

#define  NPCM_IOXCFG2		0x2B
#define  NPCM_IOXCFG2_PORT	GENMASK(3, 0)

#define  NPCM_IXOEVCFG_MASK	GENMASK(1, 0)
#define  NPCM_IXOEVCFG_FALLING	BIT(1)
#define  NPCM_IXOEVCFG_RISING	BIT(0)
#define  NPCM_IXOEVCFG_BOTH	(NPCM_IXOEVCFG_FALLING | NPCM_IXOEVCFG_RISING)

#define NPCM_CLK_MHZ	(8 * HZ_PER_MHZ)
#define NPCM_750_OPT	6
#define NPCM_845_OPT	5

#define GPIO_BANK(x)    ((x) / 8)
#define GPIO_BIT(x)     ((x) % 8)

/*
 * Select the frequency of shift clock.
 * The shift clock is a division of the APB clock.
 */
struct npcm_clk_cfg {
	unsigned int	*sft_clk;
	unsigned int	*clk_sel;
	unsigned int	cfg_opt;
};

struct npcm_sgpio {
	struct gpio_chip chip;
	struct clk *pclk;
	struct irq_chip intc;
	raw_spinlock_t lock;

	void __iomem *base;
	int irq;
	u8 nin_sgpio;
	u8 nout_sgpio;
	u8 in_port;
	u8 out_port;
	u8 int_type[MAX_NR_HW_SGPIO];
};

struct npcm_sgpio_bank {
	u8 rdata_reg;
	u8 wdata_reg;
	u8 event_config;
	u8 event_status;
};

enum npcm_sgpio_reg {
	READ_DATA,
	WRITE_DATA,
	EVENT_CFG,
	EVENT_STS,
};

static const struct npcm_sgpio_bank npcm_sgpio_banks[] = {
	{
		.wdata_reg = 0x00,
		.rdata_reg = 0x08,
		.event_config = 0x10,
		.event_status = 0x20,
	},
	{
		.wdata_reg = 0x01,
		.rdata_reg = 0x09,
		.event_config = 0x12,
		.event_status = 0x21,
	},
	{
		.wdata_reg = 0x02,
		.rdata_reg = 0x0a,
		.event_config = 0x14,
		.event_status = 0x22,
	},
	{
		.wdata_reg = 0x03,
		.rdata_reg = 0x0b,
		.event_config = 0x16,
		.event_status = 0x23,
	},
	{
		.wdata_reg = 0x04,
		.rdata_reg = 0x0c,
		.event_config = 0x18,
		.event_status = 0x24,
	},
	{
		.wdata_reg = 0x05,
		.rdata_reg = 0x0d,
		.event_config = 0x1a,
		.event_status = 0x25,
	},
	{
		.wdata_reg = 0x06,
		.rdata_reg = 0x0e,
		.event_config = 0x1c,
		.event_status = 0x26,
	},
	{
		.wdata_reg = 0x07,
		.rdata_reg = 0x0f,
		.event_config = 0x1e,
		.event_status = 0x27,
	},
};

static void __iomem *bank_reg(struct npcm_sgpio *gpio,
			      const struct npcm_sgpio_bank *bank,
			      const enum npcm_sgpio_reg reg)
{
	switch (reg) {
	case READ_DATA:
		return gpio->base + bank->rdata_reg;
	case WRITE_DATA:
		return gpio->base + bank->wdata_reg;
	case EVENT_CFG:
		return gpio->base + bank->event_config;
	case EVENT_STS:
		return gpio->base + bank->event_status;
	default:
		/* actually if code runs to here, it's an error case */
		dev_WARN(gpio->chip.parent, "Getting here is an error condition");
		return NULL;
	}
}

static const struct npcm_sgpio_bank *offset_to_bank(unsigned int offset)
{
	unsigned int bank = GPIO_BANK(offset);

	return &npcm_sgpio_banks[bank];
}

static void npcm_sgpio_irqd_to_data(struct irq_data *d,
				    struct npcm_sgpio **gpio,
				    const struct npcm_sgpio_bank **bank,
				    u8 *bit, unsigned int *offset)
{
	struct npcm_sgpio *internal;

	*offset = irqd_to_hwirq(d);
	internal = irq_data_get_irq_chip_data(d);

	*gpio = internal;
	*offset -= internal->nout_sgpio;
	*bank = offset_to_bank(*offset);
	*bit = GPIO_BIT(*offset);
}

static int npcm_sgpio_init_port(struct npcm_sgpio *gpio)
{
	u8 in_port, out_port, set_port, reg;

	in_port = GPIO_BANK(gpio->nin_sgpio);
	if (GPIO_BIT(gpio->nin_sgpio) > 0)
		in_port += 1;

	out_port = GPIO_BANK(gpio->nout_sgpio);
	if (GPIO_BIT(gpio->nout_sgpio) > 0)
		out_port += 1;

	gpio->in_port = in_port;
	gpio->out_port = out_port;
	set_port = (out_port & NPCM_IOXCFG2_PORT) << 4 |
		   (in_port & NPCM_IOXCFG2_PORT);
	iowrite8(set_port, gpio->base + NPCM_IOXCFG2);

	reg = ioread8(gpio->base + NPCM_IOXCFG2);

	return reg == set_port ? 0 : -EINVAL;

}

static int npcm_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
{
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);

	return offset <	gpio->nout_sgpio ? -EINVAL : 0;

}

static int npcm_sgpio_dir_out(struct gpio_chip *gc, unsigned int offset, int val)
{
	gc->set(gc, offset, val);

	return 0;
}

static int npcm_sgpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);

	if (offset < gpio->nout_sgpio)
		return GPIO_LINE_DIRECTION_OUT;

	return GPIO_LINE_DIRECTION_IN;
}

static void npcm_sgpio_set(struct gpio_chip *gc, unsigned int offset, int val)
{
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
	const struct  npcm_sgpio_bank *bank = offset_to_bank(offset);
	void __iomem *addr;
	u8 reg = 0;

	addr = bank_reg(gpio, bank, WRITE_DATA);
	reg = ioread8(addr);

	if (val)
		reg |= BIT(GPIO_BIT(offset));
	else
		reg &= ~BIT(GPIO_BIT(offset));

	iowrite8(reg, addr);
}

static int npcm_sgpio_get(struct gpio_chip *gc, unsigned int offset)
{
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
	const struct  npcm_sgpio_bank *bank;
	void __iomem *addr;
	u8 reg;

	if (offset < gpio->nout_sgpio) {
		bank = offset_to_bank(offset);
		addr = bank_reg(gpio, bank, WRITE_DATA);
	} else {
		offset -= gpio->nout_sgpio;
		bank = offset_to_bank(offset);
		addr = bank_reg(gpio, bank, READ_DATA);
	}

	reg = ioread8(addr);

	return !!(reg & BIT(GPIO_BIT(offset)));
}

static void npcm_sgpio_setup_enable(struct npcm_sgpio *gpio, bool enable)
{
	u8 reg;

	reg = ioread8(gpio->base + NPCM_IOXCTS);
	reg = (reg & ~NPCM_IOXCTS_RD_MODE) | NPCM_IOXCTS_RD_MODE_PERIODIC;

	if (enable)
		reg |= NPCM_IOXCTS_IOXIF_EN;
	else
		reg &= ~NPCM_IOXCTS_IOXIF_EN;

	iowrite8(reg, gpio->base + NPCM_IOXCTS);
}

static int npcm_sgpio_setup_clk(struct npcm_sgpio *gpio,
				const struct npcm_clk_cfg *clk_cfg)
{
	unsigned long apb_freq;
	u32 val;
	u8 tmp;
	int i;

	apb_freq = clk_get_rate(gpio->pclk);
	tmp = ioread8(gpio->base + NPCM_IOXCFG1) & ~NPCM_IOXCFG1_SFT_CLK;

	for (i = clk_cfg->cfg_opt-1; i > 0; i--) {
		val = apb_freq / clk_cfg->sft_clk[i];
		if (NPCM_CLK_MHZ > val) {
			iowrite8(clk_cfg->clk_sel[i] | tmp,
				 gpio->base + NPCM_IOXCFG1);
			return 0;
		}
	}

	return -EINVAL;
}

static void npcm_sgpio_irq_init_valid_mask(struct gpio_chip *gc,
					   unsigned long *valid_mask,
					   unsigned int ngpios)
{
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);

	/* input GPIOs in the high range */
	bitmap_set(valid_mask, gpio->nout_sgpio, gpio->nin_sgpio);
	bitmap_clear(valid_mask, 0, gpio->nout_sgpio);
}

static void npcm_sgpio_irq_set_mask(struct irq_data *d, bool set)
{
	const struct npcm_sgpio_bank *bank;
	struct npcm_sgpio *gpio;
	unsigned long flags;
	void __iomem *addr;
	unsigned int offset;
	u16 reg, type;
	u8 bit;

	npcm_sgpio_irqd_to_data(d, &gpio, &bank, &bit, &offset);
	addr = bank_reg(gpio, bank, EVENT_CFG);

	reg = ioread16(addr);
	if (set) {
		reg &= ~(NPCM_IXOEVCFG_MASK << (bit * 2));
	} else {
		type = gpio->int_type[offset];
		reg |= (type << (bit * 2));
	}

	raw_spin_lock_irqsave(&gpio->lock, flags);

	npcm_sgpio_setup_enable(gpio, false);

	iowrite16(reg, addr);

	npcm_sgpio_setup_enable(gpio, true);

	addr = bank_reg(gpio, bank, EVENT_STS);
	reg = ioread8(addr);
	reg |= BIT(bit);
	iowrite8(reg, addr);

	raw_spin_unlock_irqrestore(&gpio->lock, flags);
}

static void npcm_sgpio_irq_ack(struct irq_data *d)
{
	const struct npcm_sgpio_bank *bank;
	struct npcm_sgpio *gpio;
	unsigned long flags;
	void __iomem *status_addr;
	unsigned int offset;
	u8 bit;

	npcm_sgpio_irqd_to_data(d, &gpio, &bank, &bit, &offset);
	status_addr = bank_reg(gpio, bank, EVENT_STS);
	raw_spin_lock_irqsave(&gpio->lock, flags);
	iowrite8(BIT(bit), status_addr);
	raw_spin_unlock_irqrestore(&gpio->lock, flags);
}

static void npcm_sgpio_irq_mask(struct irq_data *d)
{
	npcm_sgpio_irq_set_mask(d, true);
}

static void npcm_sgpio_irq_unmask(struct irq_data *d)
{
	npcm_sgpio_irq_set_mask(d, false);
}

static int npcm_sgpio_set_type(struct irq_data *d, unsigned int type)
{
	const struct npcm_sgpio_bank *bank;
	irq_flow_handler_t handler;
	struct npcm_sgpio *gpio;
	unsigned long flags;
	void __iomem *addr;
	unsigned int offset;
	u16 reg, val;
	u8 bit;

	npcm_sgpio_irqd_to_data(d, &gpio, &bank, &bit, &offset);

	switch (type & IRQ_TYPE_SENSE_MASK) {
	case IRQ_TYPE_EDGE_BOTH:
		val = NPCM_IXOEVCFG_BOTH;
		break;
	case IRQ_TYPE_EDGE_RISING:
	case IRQ_TYPE_LEVEL_HIGH:
		val = NPCM_IXOEVCFG_RISING;
		break;
	case IRQ_TYPE_EDGE_FALLING:
	case IRQ_TYPE_LEVEL_LOW:
		val = NPCM_IXOEVCFG_FALLING;
		break;
	default:
		return -EINVAL;
	}

	if (type & IRQ_TYPE_LEVEL_MASK)
		handler = handle_level_irq;
	else
		handler = handle_edge_irq;

	gpio->int_type[offset] = val;

	raw_spin_lock_irqsave(&gpio->lock, flags);
	npcm_sgpio_setup_enable(gpio, false);
	addr = bank_reg(gpio, bank, EVENT_CFG);
	reg = ioread16(addr);

	reg |= (val << (bit * 2));

	iowrite16(reg, addr);
	npcm_sgpio_setup_enable(gpio, true);
	raw_spin_unlock_irqrestore(&gpio->lock, flags);

	irq_set_handler_locked(d, handler);

	return 0;
}

static void npcm_sgpio_irq_handler(struct irq_desc *desc)
{
	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
	struct irq_chip *ic = irq_desc_get_chip(desc);
	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
	unsigned int i, j, girq;
	unsigned long reg;

	chained_irq_enter(ic, desc);

	for (i = 0; i < ARRAY_SIZE(npcm_sgpio_banks); i++) {
		const struct npcm_sgpio_bank *bank = &npcm_sgpio_banks[i];

		reg = ioread8(bank_reg(gpio, bank, EVENT_STS));
		for_each_set_bit(j, &reg, 8) {
			girq = irq_find_mapping(gc->irq.domain,
						i * 8 + gpio->nout_sgpio + j);
			generic_handle_domain_irq(gc->irq.domain, girq);
		}
	}

	chained_irq_exit(ic, desc);
}

static const struct irq_chip sgpio_irq_chip = {
	.name = "sgpio-irq",
	.irq_ack = npcm_sgpio_irq_ack,
	.irq_mask = npcm_sgpio_irq_mask,
	.irq_unmask = npcm_sgpio_irq_unmask,
	.irq_set_type = npcm_sgpio_set_type,
	.flags	= IRQCHIP_IMMUTABLE | IRQCHIP_MASK_ON_SUSPEND,
	GPIOCHIP_IRQ_RESOURCE_HELPERS,
};

static int npcm_sgpio_setup_irqs(struct npcm_sgpio *gpio,
				 struct platform_device *pdev)
{
	int rc, i;
	struct gpio_irq_chip *irq;

	rc = platform_get_irq(pdev, 0);
	if (rc < 0)
		return rc;

	gpio->irq = rc;

	npcm_sgpio_setup_enable(gpio, false);

	/* Disable IRQ and clear Interrupt status registers for all SGPIO Pins. */
	for (i = 0; i < ARRAY_SIZE(npcm_sgpio_banks); i++) {
		const struct npcm_sgpio_bank *bank = &npcm_sgpio_banks[i];

		iowrite16(0, bank_reg(gpio, bank, EVENT_CFG));
		iowrite8(0xff, bank_reg(gpio, bank, EVENT_STS));
	}

	irq = &gpio->chip.irq;
	gpio_irq_chip_set_chip(irq, &sgpio_irq_chip);
	irq->init_valid_mask = npcm_sgpio_irq_init_valid_mask;
	irq->handler = handle_bad_irq;
	irq->default_type = IRQ_TYPE_NONE;
	irq->parent_handler = npcm_sgpio_irq_handler;
	irq->parent_handler_data = gpio;
	irq->parents = &gpio->irq;
	irq->num_parents = 1;

	return 0;
}

static int npcm_sgpio_probe(struct platform_device *pdev)
{
	struct npcm_sgpio *gpio;
	const struct npcm_clk_cfg *clk_cfg;
	int rc;
	u32 nin_gpios, nout_gpios;

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

	gpio->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(gpio->base))
		return PTR_ERR(gpio->base);

	clk_cfg = device_get_match_data(&pdev->dev);
	if (!clk_cfg)
		return -EINVAL;

	rc = device_property_read_u32(&pdev->dev, "nuvoton,input-ngpios",
				      &nin_gpios);
	if (rc < 0)
		return dev_err_probe(&pdev->dev, rc, "Could not read ngpios property\n");

	rc = device_property_read_u32(&pdev->dev, "nuvoton,output-ngpios",
				      &nout_gpios);
	if (rc < 0)
		return dev_err_probe(&pdev->dev, rc, "Could not read ngpios property\n");

	gpio->nin_sgpio = nin_gpios;
	gpio->nout_sgpio = nout_gpios;
	if (gpio->nin_sgpio > MAX_NR_HW_SGPIO ||
	    gpio->nout_sgpio > MAX_NR_HW_SGPIO)
		return dev_err_probe(&pdev->dev, -EINVAL, "Number of GPIOs exceeds the maximum of %d: input: %d output: %d\n", MAX_NR_HW_SGPIO, nin_gpios, nout_gpios);

	gpio->pclk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(gpio->pclk))
		return dev_err_probe(&pdev->dev, PTR_ERR(gpio->pclk), "Could not get pclk\n");

	rc = npcm_sgpio_setup_clk(gpio, clk_cfg);
	if (rc < 0)
		return dev_err_probe(&pdev->dev, rc, "Failed to setup clock\n");

	raw_spin_lock_init(&gpio->lock);
	gpio->chip.parent = &pdev->dev;
	gpio->chip.ngpio = gpio->nin_sgpio + gpio->nout_sgpio;
	gpio->chip.direction_input = npcm_sgpio_dir_in;
	gpio->chip.direction_output = npcm_sgpio_dir_out;
	gpio->chip.get_direction = npcm_sgpio_get_direction;
	gpio->chip.get = npcm_sgpio_get;
	gpio->chip.set = npcm_sgpio_set;
	gpio->chip.label = dev_name(&pdev->dev);
	gpio->chip.base = -1;

	rc = npcm_sgpio_init_port(gpio);
	if (rc < 0)
		return rc;

	rc = npcm_sgpio_setup_irqs(gpio, pdev);
	if (rc < 0)
		return rc;

	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
	if (rc)
		return dev_err_probe(&pdev->dev, rc, "GPIO registering failed\n");

	npcm_sgpio_setup_enable(gpio, true);

	return 0;
}

static unsigned int npcm750_SFT_CLK[NPCM_750_OPT] = {
	1024, 32, 8, 4, 3, 2,
};

static unsigned int npcm750_CLK_SEL[NPCM_750_OPT] = {
	0x00, 0x05, 0x07, 0x0C, 0x0D, 0x0E,
};

static unsigned int npcm845_SFT_CLK[NPCM_845_OPT] = {
	1024, 32, 16, 8, 4,
};

static unsigned int npcm845_CLK_SEL[NPCM_845_OPT] = {
	0x00, 0x05, 0x06, 0x07, 0x0C,
};

static struct npcm_clk_cfg npcm750_sgpio_pdata = {
	.sft_clk = npcm750_SFT_CLK,
	.clk_sel = npcm750_CLK_SEL,
	.cfg_opt = NPCM_750_OPT,
};

static const struct npcm_clk_cfg npcm845_sgpio_pdata = {
	.sft_clk = npcm845_SFT_CLK,
	.clk_sel = npcm845_CLK_SEL,
	.cfg_opt = NPCM_845_OPT,
};

static const struct of_device_id npcm_sgpio_of_table[] = {
	{ .compatible = "nuvoton,npcm750-sgpio", .data = &npcm750_sgpio_pdata, },
	{ .compatible = "nuvoton,npcm845-sgpio", .data = &npcm845_sgpio_pdata, },
	{}
};
MODULE_DEVICE_TABLE(of, npcm_sgpio_of_table);

static struct platform_driver npcm_sgpio_driver = {
	.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = npcm_sgpio_of_table,
	},
	.probe	= npcm_sgpio_probe,
};
module_platform_driver(npcm_sgpio_driver);

MODULE_AUTHOR("Jim Liu <jjliu0@nuvoton.com>");
MODULE_AUTHOR("Joseph Liu <kwliu@nuvoton.com>");
MODULE_DESCRIPTION("Nuvoton NPCM Serial GPIO Driver");
MODULE_LICENSE("GPL v2");