// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

#define PDC_MAX_IRQS		126

#define CLEAR_INTR(reg, intr)	(reg & ~(1 << intr))
#define ENABLE_INTR(reg, intr)	(reg | (1 << intr))

#define IRQ_ENABLE_BANK		0x10
#define IRQ_i_CFG		0x110

struct pdc_pin_region {
	u32 pin_base;
	u32 parent_base;
	u32 cnt;
};

static DEFINE_RAW_SPINLOCK(pdc_lock);
static void __iomem *pdc_base;
static struct pdc_pin_region *pdc_region;
static int pdc_region_cnt;

static void pdc_reg_write(int reg, u32 i, u32 val)
{
	writel_relaxed(val, pdc_base + reg + i * sizeof(u32));
}

static u32 pdc_reg_read(int reg, u32 i)
{
	return readl_relaxed(pdc_base + reg + i * sizeof(u32));
}

static void pdc_enable_intr(struct irq_data *d, bool on)
{
	int pin_out = d->hwirq;
	unsigned long flags;
	u32 index, mask;
	u32 enable;

	index = pin_out / 32;
	mask = pin_out % 32;

	raw_spin_lock_irqsave(&pdc_lock, flags);
	enable = pdc_reg_read(IRQ_ENABLE_BANK, index);
	enable = on ? ENABLE_INTR(enable, mask) : CLEAR_INTR(enable, mask);
	pdc_reg_write(IRQ_ENABLE_BANK, index, enable);
	raw_spin_unlock_irqrestore(&pdc_lock, flags);
}

static void qcom_pdc_gic_mask(struct irq_data *d)
{
	pdc_enable_intr(d, false);
	irq_chip_mask_parent(d);
}

static void qcom_pdc_gic_unmask(struct irq_data *d)
{
	pdc_enable_intr(d, true);
	irq_chip_unmask_parent(d);
}

/*
 * GIC does not handle falling edge or active low. To allow falling edge and
 * active low interrupts to be handled at GIC, PDC has an inverter that inverts
 * falling edge into a rising edge and active low into an active high.
 * For the inverter to work, the polarity bit in the IRQ_CONFIG register has to
 * set as per the table below.
 * Level sensitive active low    LOW
 * Rising edge sensitive         NOT USED
 * Falling edge sensitive        LOW
 * Dual Edge sensitive           NOT USED
 * Level sensitive active High   HIGH
 * Falling Edge sensitive        NOT USED
 * Rising edge sensitive         HIGH
 * Dual Edge sensitive           HIGH
 */
enum pdc_irq_config_bits {
	PDC_LEVEL_LOW		= 0b000,
	PDC_EDGE_FALLING	= 0b010,
	PDC_LEVEL_HIGH		= 0b100,
	PDC_EDGE_RISING		= 0b110,
	PDC_EDGE_DUAL		= 0b111,
};

/**
 * qcom_pdc_gic_set_type: Configure PDC for the interrupt
 *
 * @d: the interrupt data
 * @type: the interrupt type
 *
 * If @type is edge triggered, forward that as Rising edge as PDC
 * takes care of converting falling edge to rising edge signal
 * If @type is level, then forward that as level high as PDC
 * takes care of converting falling edge to rising edge signal
 */
static int qcom_pdc_gic_set_type(struct irq_data *d, unsigned int type)
{
	int pin_out = d->hwirq;
	enum pdc_irq_config_bits pdc_type;

	switch (type) {
	case IRQ_TYPE_EDGE_RISING:
		pdc_type = PDC_EDGE_RISING;
		break;
	case IRQ_TYPE_EDGE_FALLING:
		pdc_type = PDC_EDGE_FALLING;
		type = IRQ_TYPE_EDGE_RISING;
		break;
	case IRQ_TYPE_EDGE_BOTH:
		pdc_type = PDC_EDGE_DUAL;
		type = IRQ_TYPE_EDGE_RISING;
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		pdc_type = PDC_LEVEL_HIGH;
		break;
	case IRQ_TYPE_LEVEL_LOW:
		pdc_type = PDC_LEVEL_LOW;
		type = IRQ_TYPE_LEVEL_HIGH;
		break;
	default:
		WARN_ON(1);
		return -EINVAL;
	}

	pdc_reg_write(IRQ_i_CFG, pin_out, pdc_type);

	return irq_chip_set_type_parent(d, type);
}

static struct irq_chip qcom_pdc_gic_chip = {
	.name			= "PDC",
	.irq_eoi		= irq_chip_eoi_parent,
	.irq_mask		= qcom_pdc_gic_mask,
	.irq_unmask		= qcom_pdc_gic_unmask,
	.irq_retrigger		= irq_chip_retrigger_hierarchy,
	.irq_set_type		= qcom_pdc_gic_set_type,
	.flags			= IRQCHIP_MASK_ON_SUSPEND |
				  IRQCHIP_SET_TYPE_MASKED |
				  IRQCHIP_SKIP_SET_WAKE,
	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
	.irq_set_affinity	= irq_chip_set_affinity_parent,
};

static irq_hw_number_t get_parent_hwirq(int pin)
{
	int i;
	struct pdc_pin_region *region;

	for (i = 0; i < pdc_region_cnt; i++) {
		region = &pdc_region[i];
		if (pin >= region->pin_base &&
		    pin < region->pin_base + region->cnt)
			return (region->parent_base + pin - region->pin_base);
	}

	WARN_ON(1);
	return ~0UL;
}

static int qcom_pdc_translate(struct irq_domain *d, struct irq_fwspec *fwspec,
			      unsigned long *hwirq, unsigned int *type)
{
	if (is_of_node(fwspec->fwnode)) {
		if (fwspec->param_count != 2)
			return -EINVAL;

		*hwirq = fwspec->param[0];
		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
		return 0;
	}

	return -EINVAL;
}

static int qcom_pdc_alloc(struct irq_domain *domain, unsigned int virq,
			  unsigned int nr_irqs, void *data)
{
	struct irq_fwspec *fwspec = data;
	struct irq_fwspec parent_fwspec;
	irq_hw_number_t hwirq, parent_hwirq;
	unsigned int type;
	int ret;

	ret = qcom_pdc_translate(domain, fwspec, &hwirq, &type);
	if (ret)
		return -EINVAL;

	parent_hwirq = get_parent_hwirq(hwirq);
	if (parent_hwirq == ~0UL)
		return -EINVAL;

	ret  = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
					     &qcom_pdc_gic_chip, NULL);
	if (ret)
		return ret;

	if (type & IRQ_TYPE_EDGE_BOTH)
		type = IRQ_TYPE_EDGE_RISING;

	if (type & IRQ_TYPE_LEVEL_MASK)
		type = IRQ_TYPE_LEVEL_HIGH;

	parent_fwspec.fwnode      = domain->parent->fwnode;
	parent_fwspec.param_count = 3;
	parent_fwspec.param[0]    = 0;
	parent_fwspec.param[1]    = parent_hwirq;
	parent_fwspec.param[2]    = type;

	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs,
					    &parent_fwspec);
}

static const struct irq_domain_ops qcom_pdc_ops = {
	.translate	= qcom_pdc_translate,
	.alloc		= qcom_pdc_alloc,
	.free		= irq_domain_free_irqs_common,
};

static int pdc_setup_pin_mapping(struct device_node *np)
{
	int ret, n;

	n = of_property_count_elems_of_size(np, "qcom,pdc-ranges", sizeof(u32));
	if (n <= 0 || n % 3)
		return -EINVAL;

	pdc_region_cnt = n / 3;
	pdc_region = kcalloc(pdc_region_cnt, sizeof(*pdc_region), GFP_KERNEL);
	if (!pdc_region) {
		pdc_region_cnt = 0;
		return -ENOMEM;
	}

	for (n = 0; n < pdc_region_cnt; n++) {
		ret = of_property_read_u32_index(np, "qcom,pdc-ranges",
						 n * 3 + 0,
						 &pdc_region[n].pin_base);
		if (ret)
			return ret;
		ret = of_property_read_u32_index(np, "qcom,pdc-ranges",
						 n * 3 + 1,
						 &pdc_region[n].parent_base);
		if (ret)
			return ret;
		ret = of_property_read_u32_index(np, "qcom,pdc-ranges",
						 n * 3 + 2,
						 &pdc_region[n].cnt);
		if (ret)
			return ret;
	}

	return 0;
}

static int qcom_pdc_init(struct device_node *node, struct device_node *parent)
{
	struct irq_domain *parent_domain, *pdc_domain;
	int ret;

	pdc_base = of_iomap(node, 0);
	if (!pdc_base) {
		pr_err("%pOF: unable to map PDC registers\n", node);
		return -ENXIO;
	}

	parent_domain = irq_find_host(parent);
	if (!parent_domain) {
		pr_err("%pOF: unable to find PDC's parent domain\n", node);
		ret = -ENXIO;
		goto fail;
	}

	ret = pdc_setup_pin_mapping(node);
	if (ret) {
		pr_err("%pOF: failed to init PDC pin-hwirq mapping\n", node);
		goto fail;
	}

	pdc_domain = irq_domain_create_hierarchy(parent_domain, 0, PDC_MAX_IRQS,
						 of_fwnode_handle(node),
						 &qcom_pdc_ops, NULL);
	if (!pdc_domain) {
		pr_err("%pOF: GIC domain add failed\n", node);
		ret = -ENOMEM;
		goto fail;
	}

	return 0;

fail:
	kfree(pdc_region);
	iounmap(pdc_base);
	return ret;
}

IRQCHIP_DECLARE(pdc_sdm845, "qcom,sdm845-pdc", qcom_pdc_init);