/*
 * IMG PowerDown Controller (PDC)
 *
 * Copyright 2010-2013 Imagination Technologies Ltd.
 *
 * Exposes the syswake and PDC peripheral wake interrupts to the system.
 *
 */

#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/irqdomain.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

/* PDC interrupt register numbers */

#define PDC_IRQ_STATUS                  0x310
#define PDC_IRQ_ENABLE                  0x314
#define PDC_IRQ_CLEAR                   0x318
#define PDC_IRQ_ROUTE                   0x31c
#define PDC_SYS_WAKE_BASE               0x330
#define PDC_SYS_WAKE_STRIDE             0x8
#define PDC_SYS_WAKE_CONFIG_BASE        0x334
#define PDC_SYS_WAKE_CONFIG_STRIDE      0x8

/* PDC interrupt register field masks */

#define PDC_IRQ_SYS3                    0x08
#define PDC_IRQ_SYS2                    0x04
#define PDC_IRQ_SYS1                    0x02
#define PDC_IRQ_SYS0                    0x01
#define PDC_IRQ_ROUTE_WU_EN_SYS3        0x08000000
#define PDC_IRQ_ROUTE_WU_EN_SYS2        0x04000000
#define PDC_IRQ_ROUTE_WU_EN_SYS1        0x02000000
#define PDC_IRQ_ROUTE_WU_EN_SYS0        0x01000000
#define PDC_IRQ_ROUTE_WU_EN_WD          0x00040000
#define PDC_IRQ_ROUTE_WU_EN_IR          0x00020000
#define PDC_IRQ_ROUTE_WU_EN_RTC         0x00010000
#define PDC_IRQ_ROUTE_EXT_EN_SYS3       0x00000800
#define PDC_IRQ_ROUTE_EXT_EN_SYS2       0x00000400
#define PDC_IRQ_ROUTE_EXT_EN_SYS1       0x00000200
#define PDC_IRQ_ROUTE_EXT_EN_SYS0       0x00000100
#define PDC_IRQ_ROUTE_EXT_EN_WD         0x00000004
#define PDC_IRQ_ROUTE_EXT_EN_IR         0x00000002
#define PDC_IRQ_ROUTE_EXT_EN_RTC        0x00000001
#define PDC_SYS_WAKE_RESET              0x00000010
#define PDC_SYS_WAKE_INT_MODE           0x0000000e
#define PDC_SYS_WAKE_INT_MODE_SHIFT     1
#define PDC_SYS_WAKE_PIN_VAL            0x00000001

/* PDC interrupt constants */

#define PDC_SYS_WAKE_INT_LOW            0x0
#define PDC_SYS_WAKE_INT_HIGH           0x1
#define PDC_SYS_WAKE_INT_DOWN           0x2
#define PDC_SYS_WAKE_INT_UP             0x3
#define PDC_SYS_WAKE_INT_CHANGE         0x6
#define PDC_SYS_WAKE_INT_NONE           0x4

/**
 * struct pdc_intc_priv - private pdc interrupt data.
 * @nr_perips:          Number of peripheral interrupt signals.
 * @nr_syswakes:        Number of syswake signals.
 * @perip_irqs:         List of peripheral IRQ numbers handled.
 * @syswake_irq:        Shared PDC syswake IRQ number.
 * @domain:             IRQ domain for PDC peripheral and syswake IRQs.
 * @pdc_base:           Base of PDC registers.
 * @irq_route:          Cached version of PDC_IRQ_ROUTE register.
 * @lock:               Lock to protect the PDC syswake registers and the cached
 *                      values of those registers in this struct.
 */
struct pdc_intc_priv {
        unsigned int            nr_perips;
        unsigned int            nr_syswakes;
        unsigned int            *perip_irqs;
        unsigned int            syswake_irq;
        struct irq_domain       *domain;
        void __iomem            *pdc_base;

        u32                     irq_route;
        raw_spinlock_t          lock;
};

static void pdc_write(struct pdc_intc_priv *priv, unsigned int reg_offs,
                      unsigned int data)
{
        iowrite32(data, priv->pdc_base + reg_offs);
}

static unsigned int pdc_read(struct pdc_intc_priv *priv,
                             unsigned int reg_offs)
{
        return ioread32(priv->pdc_base + reg_offs);
}

/* Generic IRQ callbacks */

#define SYS0_HWIRQ      8

static unsigned int hwirq_is_syswake(irq_hw_number_t hw)
{
        return hw >= SYS0_HWIRQ;
}

static unsigned int hwirq_to_syswake(irq_hw_number_t hw)
{
        return hw - SYS0_HWIRQ;
}

static irq_hw_number_t syswake_to_hwirq(unsigned int syswake)
{
        return SYS0_HWIRQ + syswake;
}

static struct pdc_intc_priv *irqd_to_priv(struct irq_data *data)
{
        return (struct pdc_intc_priv *)data->domain->host_data;
}

/*
 * perip_irq_mask() and perip_irq_unmask() use IRQ_ROUTE which also contains
 * wake bits, therefore we cannot use the generic irqchip mask callbacks as they
 * cache the mask.
 */

static void perip_irq_mask(struct irq_data *data)
{
        struct pdc_intc_priv *priv = irqd_to_priv(data);

        raw_spin_lock(&priv->lock);
        priv->irq_route &= ~data->mask;
        pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
        raw_spin_unlock(&priv->lock);
}

static void perip_irq_unmask(struct irq_data *data)
{
        struct pdc_intc_priv *priv = irqd_to_priv(data);

        raw_spin_lock(&priv->lock);
        priv->irq_route |= data->mask;
        pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
        raw_spin_unlock(&priv->lock);
}

static int syswake_irq_set_type(struct irq_data *data, unsigned int flow_type)
{
        struct pdc_intc_priv *priv = irqd_to_priv(data);
        unsigned int syswake = hwirq_to_syswake(data->hwirq);
        unsigned int irq_mode;
        unsigned int soc_sys_wake_regoff, soc_sys_wake;

        /* translate to syswake IRQ mode */
        switch (flow_type) {
        case IRQ_TYPE_EDGE_BOTH:
                irq_mode = PDC_SYS_WAKE_INT_CHANGE;
                break;
        case IRQ_TYPE_EDGE_RISING:
                irq_mode = PDC_SYS_WAKE_INT_UP;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                irq_mode = PDC_SYS_WAKE_INT_DOWN;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                irq_mode = PDC_SYS_WAKE_INT_HIGH;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                irq_mode = PDC_SYS_WAKE_INT_LOW;
                break;
        default:
                return -EINVAL;
        }

        raw_spin_lock(&priv->lock);

        /* set the IRQ mode */
        soc_sys_wake_regoff = PDC_SYS_WAKE_BASE + syswake*PDC_SYS_WAKE_STRIDE;
        soc_sys_wake = pdc_read(priv, soc_sys_wake_regoff);
        soc_sys_wake &= ~PDC_SYS_WAKE_INT_MODE;
        soc_sys_wake |= irq_mode << PDC_SYS_WAKE_INT_MODE_SHIFT;
        pdc_write(priv, soc_sys_wake_regoff, soc_sys_wake);

        /* and update the handler */
        irq_setup_alt_chip(data, flow_type);

        raw_spin_unlock(&priv->lock);

        return 0;
}

/* applies to both peripheral and syswake interrupts */
static int pdc_irq_set_wake(struct irq_data *data, unsigned int on)
{
        struct pdc_intc_priv *priv = irqd_to_priv(data);
        irq_hw_number_t hw = data->hwirq;
        unsigned int mask = (1 << 16) << hw;
        unsigned int dst_irq;

        raw_spin_lock(&priv->lock);
        if (on)
                priv->irq_route |= mask;
        else
                priv->irq_route &= ~mask;
        pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
        raw_spin_unlock(&priv->lock);

        /* control the destination IRQ wakeup too for standby mode */
        if (hwirq_is_syswake(hw))
                dst_irq = priv->syswake_irq;
        else
                dst_irq = priv->perip_irqs[hw];
        irq_set_irq_wake(dst_irq, on);

        return 0;
}

static void pdc_intc_perip_isr(unsigned int irq, struct irq_desc *desc)
{
        struct pdc_intc_priv *priv;
        unsigned int i, irq_no;

        priv = (struct pdc_intc_priv *)irq_desc_get_handler_data(desc);

        /* find the peripheral number */
        for (i = 0; i < priv->nr_perips; ++i)
                if (irq == priv->perip_irqs[i])
                        goto found;

        /* should never get here */
        return;
found:

        /* pass on the interrupt */
        irq_no = irq_linear_revmap(priv->domain, i);
        generic_handle_irq(irq_no);
}

static void pdc_intc_syswake_isr(unsigned int irq, struct irq_desc *desc)
{
        struct pdc_intc_priv *priv;
        unsigned int syswake, irq_no;
        unsigned int status;

        priv = (struct pdc_intc_priv *)irq_desc_get_handler_data(desc);

        status = pdc_read(priv, PDC_IRQ_STATUS) &
                 pdc_read(priv, PDC_IRQ_ENABLE);
        status &= (1 << priv->nr_syswakes) - 1;

        for (syswake = 0; status; status >>= 1, ++syswake) {
                /* Has this sys_wake triggered? */
                if (!(status & 1))
                        continue;

                irq_no = irq_linear_revmap(priv->domain,
                                           syswake_to_hwirq(syswake));
                generic_handle_irq(irq_no);
        }
}

static void pdc_intc_setup(struct pdc_intc_priv *priv)
{
        int i;
        unsigned int soc_sys_wake_regoff;
        unsigned int soc_sys_wake;

        /*
         * Mask all syswake interrupts before routing, or we could receive an
         * interrupt before we're ready to handle it.
         */
        pdc_write(priv, PDC_IRQ_ENABLE, 0);

        /*
         * Enable routing of all syswakes
         * Disable all wake sources
         */
        priv->irq_route = ((PDC_IRQ_ROUTE_EXT_EN_SYS0 << priv->nr_syswakes) -
                                PDC_IRQ_ROUTE_EXT_EN_SYS0);
        pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);

        /* Initialise syswake IRQ */
        for (i = 0; i < priv->nr_syswakes; ++i) {
                /* set the IRQ mode to none */
                soc_sys_wake_regoff = PDC_SYS_WAKE_BASE + i*PDC_SYS_WAKE_STRIDE;
                soc_sys_wake = PDC_SYS_WAKE_INT_NONE
                                << PDC_SYS_WAKE_INT_MODE_SHIFT;
                pdc_write(priv, soc_sys_wake_regoff, soc_sys_wake);
        }
}

static int pdc_intc_probe(struct platform_device *pdev)
{
        struct pdc_intc_priv *priv;
        struct device_node *node = pdev->dev.of_node;
        struct resource *res_regs;
        struct irq_chip_generic *gc;
        unsigned int i;
        int irq, ret;
        u32 val;

        if (!node)
                return -ENOENT;

        /* Get registers */
        res_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res_regs == NULL) {
                dev_err(&pdev->dev, "cannot find registers resource\n");
                return -ENOENT;
        }

        /* Allocate driver data */
        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv) {
                dev_err(&pdev->dev, "cannot allocate device data\n");
                return -ENOMEM;
        }
        raw_spin_lock_init(&priv->lock);
        platform_set_drvdata(pdev, priv);

        /* Ioremap the registers */
        priv->pdc_base = devm_ioremap(&pdev->dev, res_regs->start,
                                      res_regs->end - res_regs->start);
        if (!priv->pdc_base)
                return -EIO;

        /* Get number of peripherals */
        ret = of_property_read_u32(node, "num-perips", &val);
        if (ret) {
                dev_err(&pdev->dev, "No num-perips node property found\n");
                return -EINVAL;
        }
        if (val > SYS0_HWIRQ) {
                dev_err(&pdev->dev, "num-perips (%u) out of range\n", val);
                return -EINVAL;
        }
        priv->nr_perips = val;

        /* Get number of syswakes */
        ret = of_property_read_u32(node, "num-syswakes", &val);
        if (ret) {
                dev_err(&pdev->dev, "No num-syswakes node property found\n");
                return -EINVAL;
        }
        if (val > SYS0_HWIRQ) {
                dev_err(&pdev->dev, "num-syswakes (%u) out of range\n", val);
                return -EINVAL;
        }
        priv->nr_syswakes = val;

        /* Get peripheral IRQ numbers */
        priv->perip_irqs = devm_kzalloc(&pdev->dev, 4 * priv->nr_perips,
                                        GFP_KERNEL);
        if (!priv->perip_irqs) {
                dev_err(&pdev->dev, "cannot allocate perip IRQ list\n");
                return -ENOMEM;
        }
        for (i = 0; i < priv->nr_perips; ++i) {
                irq = platform_get_irq(pdev, 1 + i);
                if (irq < 0) {
                        dev_err(&pdev->dev, "cannot find perip IRQ #%u\n", i);
                        return irq;
                }
                priv->perip_irqs[i] = irq;
        }
        /* check if too many were provided */
        if (platform_get_irq(pdev, 1 + i) >= 0) {
                dev_err(&pdev->dev, "surplus perip IRQs detected\n");
                return -EINVAL;
        }

        /* Get syswake IRQ number */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "cannot find syswake IRQ\n");
                return irq;
        }
        priv->syswake_irq = irq;

        /* Set up an IRQ domain */
        priv->domain = irq_domain_add_linear(node, 16, &irq_generic_chip_ops,
                                             priv);
        if (unlikely(!priv->domain)) {
                dev_err(&pdev->dev, "cannot add IRQ domain\n");
                return -ENOMEM;
        }

        /*
         * Set up 2 generic irq chips with 2 chip types.
         * The first one for peripheral irqs (only 1 chip type used)
         * The second one for syswake irqs (edge and level chip types)
         */
        ret = irq_alloc_domain_generic_chips(priv->domain, 8, 2, "pdc",
                                             handle_level_irq, 0, 0,
                                             IRQ_GC_INIT_NESTED_LOCK);
        if (ret)
                goto err_generic;

        /* peripheral interrupt chip */

        gc = irq_get_domain_generic_chip(priv->domain, 0);
        gc->unused      = ~(BIT(priv->nr_perips) - 1);
        gc->reg_base    = priv->pdc_base;
        /*
         * IRQ_ROUTE contains wake bits, so we can't use the generic versions as
         * they cache the mask
         */
        gc->chip_types[0].regs.mask             = PDC_IRQ_ROUTE;
        gc->chip_types[0].chip.irq_mask         = perip_irq_mask;
        gc->chip_types[0].chip.irq_unmask       = perip_irq_unmask;
        gc->chip_types[0].chip.irq_set_wake     = pdc_irq_set_wake;

        /* syswake interrupt chip */

        gc = irq_get_domain_generic_chip(priv->domain, 8);
        gc->unused      = ~(BIT(priv->nr_syswakes) - 1);
        gc->reg_base    = priv->pdc_base;

        /* edge interrupts */
        gc->chip_types[0].type                  = IRQ_TYPE_EDGE_BOTH;
        gc->chip_types[0].handler               = handle_edge_irq;
        gc->chip_types[0].regs.ack              = PDC_IRQ_CLEAR;
        gc->chip_types[0].regs.mask             = PDC_IRQ_ENABLE;
        gc->chip_types[0].chip.irq_ack          = irq_gc_ack_set_bit;
        gc->chip_types[0].chip.irq_mask         = irq_gc_mask_clr_bit;
        gc->chip_types[0].chip.irq_unmask       = irq_gc_mask_set_bit;
        gc->chip_types[0].chip.irq_set_type     = syswake_irq_set_type;
        gc->chip_types[0].chip.irq_set_wake     = pdc_irq_set_wake;
        /* for standby we pass on to the shared syswake IRQ */
        gc->chip_types[0].chip.flags            = IRQCHIP_MASK_ON_SUSPEND;

        /* level interrupts */
        gc->chip_types[1].type                  = IRQ_TYPE_LEVEL_MASK;
        gc->chip_types[1].handler               = handle_level_irq;
        gc->chip_types[1].regs.ack              = PDC_IRQ_CLEAR;
        gc->chip_types[1].regs.mask             = PDC_IRQ_ENABLE;
        gc->chip_types[1].chip.irq_ack          = irq_gc_ack_set_bit;
        gc->chip_types[1].chip.irq_mask         = irq_gc_mask_clr_bit;
        gc->chip_types[1].chip.irq_unmask       = irq_gc_mask_set_bit;
        gc->chip_types[1].chip.irq_set_type     = syswake_irq_set_type;
        gc->chip_types[1].chip.irq_set_wake     = pdc_irq_set_wake;
        /* for standby we pass on to the shared syswake IRQ */
        gc->chip_types[1].chip.flags            = IRQCHIP_MASK_ON_SUSPEND;

        /* Set up the hardware to enable interrupt routing */
        pdc_intc_setup(priv);

        /* Setup chained handlers for the peripheral IRQs */
        for (i = 0; i < priv->nr_perips; ++i) {
                irq = priv->perip_irqs[i];
                irq_set_handler_data(irq, priv);
                irq_set_chained_handler(irq, pdc_intc_perip_isr);
        }

        /* Setup chained handler for the syswake IRQ */
        irq_set_handler_data(priv->syswake_irq, priv);
        irq_set_chained_handler(priv->syswake_irq, pdc_intc_syswake_isr);

        dev_info(&pdev->dev,
                 "PDC IRQ controller initialised (%u perip IRQs, %u syswake IRQs)\n",
                 priv->nr_perips,
                 priv->nr_syswakes);

        return 0;
err_generic:
        irq_domain_remove(priv->domain);
        return ret;
}

static int pdc_intc_remove(struct platform_device *pdev)
{
        struct pdc_intc_priv *priv = platform_get_drvdata(pdev);

        irq_domain_remove(priv->domain);
        return 0;
}

static const struct of_device_id pdc_intc_match[] = {
        { .compatible = "img,pdc-intc" },
        {}
};

static struct platform_driver pdc_intc_driver = {
        .driver = {
                .name           = "pdc-intc",
                .of_match_table = pdc_intc_match,
        },
        .probe = pdc_intc_probe,
        .remove = pdc_intc_remove,
};

static int __init pdc_intc_init(void)
{
        return platform_driver_register(&pdc_intc_driver);
}
core_initcall(pdc_intc_init);