/*
 *
 * Programmable Interrupt Controller functions for the Freescale MPC52xx.
 *
 * Copyright (C) 2008 Secret Lab Technologies Ltd.
 * Copyright (C) 2006 bplan GmbH
 * Copyright (C) 2004 Sylvain Munaut <tnt@246tNt.com>
 * Copyright (C) 2003 Montavista Software, Inc
 *
 * Based on the code from the 2.4 kernel by
 * Dale Farnsworth <dfarnsworth@mvista.com> and Kent Borg.
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 *
 */

/*
 * This is the device driver for the MPC5200 interrupt controller.
 *
 * hardware overview
 * -----------------
 * The MPC5200 interrupt controller groups the all interrupt sources into
 * three groups called 'critical', 'main', and 'peripheral'.  The critical
 * group has 3 irqs, External IRQ0, slice timer 0 irq, and wake from deep
 * sleep.  Main group include the other 3 external IRQs, slice timer 1, RTC,
 * gpios, and the general purpose timers.  Peripheral group contains the
 * remaining irq sources from all of the on-chip peripherals (PSCs, Ethernet,
 * USB, DMA, etc).
 *
 * virqs
 * -----
 * The Linux IRQ subsystem requires that each irq source be assigned a
 * system wide unique IRQ number starting at 1 (0 means no irq).  Since
 * systems can have multiple interrupt controllers, the virtual IRQ (virq)
 * infrastructure lets each interrupt controller to define a local set
 * of IRQ numbers and the virq infrastructure maps those numbers into
 * a unique range of the global IRQ# space.
 *
 * To define a range of virq numbers for this controller, this driver first
 * assigns a number to each of the irq groups (called the level 1 or L1
 * value).  Within each group individual irq sources are also assigned a
 * number, as defined by the MPC5200 user guide, and refers to it as the
 * level 2 or L2 value.  The virq number is determined by shifting up the
 * L1 value by MPC52xx_IRQ_L1_OFFSET and ORing it with the L2 value.
 *
 * For example, the TMR0 interrupt is irq 9 in the main group.  The
 * virq for TMR0 is calculated by ((1 << MPC52xx_IRQ_L1_OFFSET) | 9).
 *
 * The observant reader will also notice that this driver defines a 4th
 * interrupt group called 'bestcomm'.  The bestcomm group isn't physically
 * part of the MPC5200 interrupt controller, but it is used here to assign
 * a separate virq number for each bestcomm task (since any of the 16
 * bestcomm tasks can cause the bestcomm interrupt to be raised).  When a
 * bestcomm interrupt occurs (peripheral group, irq 0) this driver determines
 * which task needs servicing and returns the irq number for that task.  This
 * allows drivers which use bestcomm to define their own interrupt handlers.
 *
 * irq_chip structures
 * -------------------
 * For actually manipulating IRQs (masking, enabling, clearing, etc) this
 * driver defines four separate 'irq_chip' structures, one for the main
 * group, one for the peripherals group, one for the bestcomm group and one
 * for external interrupts.  The irq_chip structures provide the hooks needed
 * to manipulate each IRQ source, and since each group is has a separate set
 * of registers for controlling the irq, it makes sense to divide up the
 * hooks along those lines.
 *
 * You'll notice that there is not an irq_chip for the critical group and
 * you'll also notice that there is an irq_chip defined for external
 * interrupts even though there is no external interrupt group.  The reason
 * for this is that the four external interrupts are all managed with the same
 * register even though one of the external IRQs is in the critical group and
 * the other three are in the main group.  For this reason it makes sense for
 * the 4 external irqs to be managed using a separate set of hooks.  The
 * reason there is no crit irq_chip is that of the 3 irqs in the critical
 * group, only external interrupt is actually support at this time by this
 * driver and since external interrupt is the only one used, it can just
 * be directed to make use of the external irq irq_chip.
 *
 * device tree bindings
 * --------------------
 * The device tree bindings for this controller reflect the two level
 * organization of irqs in the device.  #interrupt-cells = <3> where the
 * first cell is the group number [0..3], the second cell is the irq
 * number in the group, and the third cell is the sense type (level/edge).
 * For reference, the following is a list of the interrupt property values
 * associated with external interrupt sources on the MPC5200 (just because
 * it is non-obvious to determine what the interrupts property should be
 * when reading the mpc5200 manual and it is a frequently asked question).
 *
 * External interrupts:
 * <0 0 n>      external irq0, n is sense       (n=0: level high,
 * <1 1 n>      external irq1, n is sense        n=1: edge rising,
 * <1 2 n>      external irq2, n is sense        n=2: edge falling,
 * <1 3 n>      external irq3, n is sense        n=3: level low)
 */
#undef DEBUG

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/mpc52xx.h>

/* HW IRQ mapping */
#define MPC52xx_IRQ_L1_CRIT     (0)
#define MPC52xx_IRQ_L1_MAIN     (1)
#define MPC52xx_IRQ_L1_PERP     (2)
#define MPC52xx_IRQ_L1_SDMA     (3)

#define MPC52xx_IRQ_L1_OFFSET   (6)
#define MPC52xx_IRQ_L1_MASK     (0x00c0)
#define MPC52xx_IRQ_L2_MASK     (0x003f)

#define MPC52xx_IRQ_HIGHTESTHWIRQ (0xd0)


/* MPC5200 device tree match tables */
static const struct of_device_id mpc52xx_pic_ids[] __initconst = {
        { .compatible = "fsl,mpc5200-pic", },
        { .compatible = "mpc5200-pic", },
        {}
};
static const struct of_device_id mpc52xx_sdma_ids[] __initconst = {
        { .compatible = "fsl,mpc5200-bestcomm", },
        { .compatible = "mpc5200-bestcomm", },
        {}
};

static struct mpc52xx_intr __iomem *intr;
static struct mpc52xx_sdma __iomem *sdma;
static struct irq_domain *mpc52xx_irqhost = NULL;

static unsigned char mpc52xx_map_senses[4] = {
        IRQ_TYPE_LEVEL_HIGH,
        IRQ_TYPE_EDGE_RISING,
        IRQ_TYPE_EDGE_FALLING,
        IRQ_TYPE_LEVEL_LOW,
};

/* Utility functions */
static inline void io_be_setbit(u32 __iomem *addr, int bitno)
{
        out_be32(addr, in_be32(addr) | (1 << bitno));
}

static inline void io_be_clrbit(u32 __iomem *addr, int bitno)
{
        out_be32(addr, in_be32(addr) & ~(1 << bitno));
}

/*
 * IRQ[0-3] interrupt irq_chip
 */
static void mpc52xx_extirq_mask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_clrbit(&intr->ctrl, 11 - l2irq);
}

static void mpc52xx_extirq_unmask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_setbit(&intr->ctrl, 11 - l2irq);
}

static void mpc52xx_extirq_ack(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_setbit(&intr->ctrl, 27-l2irq);
}

static int mpc52xx_extirq_set_type(struct irq_data *d, unsigned int flow_type)
{
        u32 ctrl_reg, type;
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        void *handler = handle_level_irq;

        pr_debug("%s: irq=%x. l2=%d flow_type=%d\n", __func__,
                (int) irqd_to_hwirq(d), l2irq, flow_type);

        switch (flow_type) {
        case IRQF_TRIGGER_HIGH: type = 0; break;
        case IRQF_TRIGGER_RISING: type = 1; handler = handle_edge_irq; break;
        case IRQF_TRIGGER_FALLING: type = 2; handler = handle_edge_irq; break;
        case IRQF_TRIGGER_LOW: type = 3; break;
        default:
                type = 0;
        }

        ctrl_reg = in_be32(&intr->ctrl);
        ctrl_reg &= ~(0x3 << (22 - (l2irq * 2)));
        ctrl_reg |= (type << (22 - (l2irq * 2)));
        out_be32(&intr->ctrl, ctrl_reg);

        irq_set_handler_locked(d, handler);

        return 0;
}

static struct irq_chip mpc52xx_extirq_irqchip = {
        .name = "MPC52xx External",
        .irq_mask = mpc52xx_extirq_mask,
        .irq_unmask = mpc52xx_extirq_unmask,
        .irq_ack = mpc52xx_extirq_ack,
        .irq_set_type = mpc52xx_extirq_set_type,
};

/*
 * Main interrupt irq_chip
 */
static int mpc52xx_null_set_type(struct irq_data *d, unsigned int flow_type)
{
        return 0; /* Do nothing so that the sense mask will get updated */
}

static void mpc52xx_main_mask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_setbit(&intr->main_mask, 16 - l2irq);
}

static void mpc52xx_main_unmask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_clrbit(&intr->main_mask, 16 - l2irq);
}

static struct irq_chip mpc52xx_main_irqchip = {
        .name = "MPC52xx Main",
        .irq_mask = mpc52xx_main_mask,
        .irq_mask_ack = mpc52xx_main_mask,
        .irq_unmask = mpc52xx_main_unmask,
        .irq_set_type = mpc52xx_null_set_type,
};

/*
 * Peripherals interrupt irq_chip
 */
static void mpc52xx_periph_mask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_setbit(&intr->per_mask, 31 - l2irq);
}

static void mpc52xx_periph_unmask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_clrbit(&intr->per_mask, 31 - l2irq);
}

static struct irq_chip mpc52xx_periph_irqchip = {
        .name = "MPC52xx Peripherals",
        .irq_mask = mpc52xx_periph_mask,
        .irq_mask_ack = mpc52xx_periph_mask,
        .irq_unmask = mpc52xx_periph_unmask,
        .irq_set_type = mpc52xx_null_set_type,
};

/*
 * SDMA interrupt irq_chip
 */
static void mpc52xx_sdma_mask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_setbit(&sdma->IntMask, l2irq);
}

static void mpc52xx_sdma_unmask(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        io_be_clrbit(&sdma->IntMask, l2irq);
}

static void mpc52xx_sdma_ack(struct irq_data *d)
{
        int l2irq = irqd_to_hwirq(d) & MPC52xx_IRQ_L2_MASK;
        out_be32(&sdma->IntPend, 1 << l2irq);
}

static struct irq_chip mpc52xx_sdma_irqchip = {
        .name = "MPC52xx SDMA",
        .irq_mask = mpc52xx_sdma_mask,
        .irq_unmask = mpc52xx_sdma_unmask,
        .irq_ack = mpc52xx_sdma_ack,
        .irq_set_type = mpc52xx_null_set_type,
};

/**
 * mpc52xx_is_extirq - Returns true if hwirq number is for an external IRQ
 */
static int mpc52xx_is_extirq(int l1, int l2)
{
        return ((l1 == 0) && (l2 == 0)) ||
               ((l1 == 1) && (l2 >= 1) && (l2 <= 3));
}

/**
 * mpc52xx_irqhost_xlate - translate virq# from device tree interrupts property
 */
static int mpc52xx_irqhost_xlate(struct irq_domain *h, struct device_node *ct,
                                 const u32 *intspec, unsigned int intsize,
                                 irq_hw_number_t *out_hwirq,
                                 unsigned int *out_flags)
{
        int intrvect_l1;
        int intrvect_l2;
        int intrvect_type;
        int intrvect_linux;

        if (intsize != 3)
                return -1;

        intrvect_l1 = (int)intspec[0];
        intrvect_l2 = (int)intspec[1];
        intrvect_type = (int)intspec[2] & 0x3;

        intrvect_linux = (intrvect_l1 << MPC52xx_IRQ_L1_OFFSET) &
                         MPC52xx_IRQ_L1_MASK;
        intrvect_linux |= intrvect_l2 & MPC52xx_IRQ_L2_MASK;

        *out_hwirq = intrvect_linux;
        *out_flags = IRQ_TYPE_LEVEL_LOW;
        if (mpc52xx_is_extirq(intrvect_l1, intrvect_l2))
                *out_flags = mpc52xx_map_senses[intrvect_type];

        pr_debug("return %x, l1=%d, l2=%d\n", intrvect_linux, intrvect_l1,
                 intrvect_l2);
        return 0;
}

/**
 * mpc52xx_irqhost_map - Hook to map from virq to an irq_chip structure
 */
static int mpc52xx_irqhost_map(struct irq_domain *h, unsigned int virq,
                               irq_hw_number_t irq)
{
        int l1irq;
        int l2irq;
        struct irq_chip *uninitialized_var(irqchip);
        void *hndlr;
        int type;
        u32 reg;

        l1irq = (irq & MPC52xx_IRQ_L1_MASK) >> MPC52xx_IRQ_L1_OFFSET;
        l2irq = irq & MPC52xx_IRQ_L2_MASK;

        /*
         * External IRQs are handled differently by the hardware so they are
         * handled by a dedicated irq_chip structure.
         */
        if (mpc52xx_is_extirq(l1irq, l2irq)) {
                reg = in_be32(&intr->ctrl);
                type = mpc52xx_map_senses[(reg >> (22 - l2irq * 2)) & 0x3];
                if ((type == IRQ_TYPE_EDGE_FALLING) ||
                    (type == IRQ_TYPE_EDGE_RISING))
                        hndlr = handle_edge_irq;
                else
                        hndlr = handle_level_irq;

                irq_set_chip_and_handler(virq, &mpc52xx_extirq_irqchip, hndlr);
                pr_debug("%s: External IRQ%i virq=%x, hw=%x. type=%x\n",
                         __func__, l2irq, virq, (int)irq, type);
                return 0;
        }

        /* It is an internal SOC irq.  Choose the correct irq_chip */
        switch (l1irq) {
        case MPC52xx_IRQ_L1_MAIN: irqchip = &mpc52xx_main_irqchip; break;
        case MPC52xx_IRQ_L1_PERP: irqchip = &mpc52xx_periph_irqchip; break;
        case MPC52xx_IRQ_L1_SDMA: irqchip = &mpc52xx_sdma_irqchip; break;
        case MPC52xx_IRQ_L1_CRIT:
                pr_warn("%s: Critical IRQ #%d is unsupported! Nopping it.\n",
                        __func__, l2irq);
                irq_set_chip(virq, &no_irq_chip);
                return 0;
        }

        irq_set_chip_and_handler(virq, irqchip, handle_level_irq);
        pr_debug("%s: virq=%x, l1=%i, l2=%i\n", __func__, virq, l1irq, l2irq);

        return 0;
}

static const struct irq_domain_ops mpc52xx_irqhost_ops = {
        .xlate = mpc52xx_irqhost_xlate,
        .map = mpc52xx_irqhost_map,
};

/**
 * mpc52xx_init_irq - Initialize and register with the virq subsystem
 *
 * Hook for setting up IRQs on an mpc5200 system.  A pointer to this function
 * is to be put into the machine definition structure.
 *
 * This function searches the device tree for an MPC5200 interrupt controller,
 * initializes it, and registers it with the virq subsystem.
 */
void __init mpc52xx_init_irq(void)
{
        u32 intr_ctrl;
        struct device_node *picnode;
        struct device_node *np;

        /* Remap the necessary zones */
        picnode = of_find_matching_node(NULL, mpc52xx_pic_ids);
        intr = of_iomap(picnode, 0);
        if (!intr)
                panic(__FILE__  ": find_and_map failed on 'mpc5200-pic'. "
                                "Check node !");

        np = of_find_matching_node(NULL, mpc52xx_sdma_ids);
        sdma = of_iomap(np, 0);
        of_node_put(np);
        if (!sdma)
                panic(__FILE__  ": find_and_map failed on 'mpc5200-bestcomm'. "
                                "Check node !");

        pr_debug("MPC5200 IRQ controller mapped to 0x%p\n", intr);

        /* Disable all interrupt sources. */
        out_be32(&sdma->IntPend, 0xffffffff);   /* 1 means clear pending */
        out_be32(&sdma->IntMask, 0xffffffff);   /* 1 means disabled */
        out_be32(&intr->per_mask, 0x7ffffc00);  /* 1 means disabled */
        out_be32(&intr->main_mask, 0x00010fff); /* 1 means disabled */
        intr_ctrl = in_be32(&intr->ctrl);
        intr_ctrl &= 0x00ff0000;        /* Keeps IRQ[0-3] config */
        intr_ctrl |=    0x0f000000 |    /* clear IRQ 0-3 */
                        0x00001000 |    /* MEE master external enable */
                        0x00000000 |    /* 0 means disable IRQ 0-3 */
                        0x00000001;     /* CEb route critical normally */
        out_be32(&intr->ctrl, intr_ctrl);

        /* Zero a bunch of the priority settings. */
        out_be32(&intr->per_pri1, 0);
        out_be32(&intr->per_pri2, 0);
        out_be32(&intr->per_pri3, 0);
        out_be32(&intr->main_pri1, 0);
        out_be32(&intr->main_pri2, 0);

        /*
         * As last step, add an irq host to translate the real
         * hw irq information provided by the ofw to linux virq
         */
        mpc52xx_irqhost = irq_domain_add_linear(picnode,
                                         MPC52xx_IRQ_HIGHTESTHWIRQ,
                                         &mpc52xx_irqhost_ops, NULL);

        if (!mpc52xx_irqhost)
                panic(__FILE__ ": Cannot allocate the IRQ host\n");

        irq_set_default_host(mpc52xx_irqhost);

        pr_info("MPC52xx PIC is up and running!\n");
}

/**
 * mpc52xx_get_irq - Get pending interrupt number hook function
 *
 * Called by the interrupt handler to determine what IRQ handler needs to be
 * executed.
 *
 * Status of pending interrupts is determined by reading the encoded status
 * register.  The encoded status register has three fields; one for each of the
 * types of interrupts defined by the controller - 'critical', 'main' and
 * 'peripheral'.  This function reads the status register and returns the IRQ
 * number associated with the highest priority pending interrupt.  'Critical'
 * interrupts have the highest priority, followed by 'main' interrupts, and
 * then 'peripheral'.
 *
 * The mpc5200 interrupt controller can be configured to boost the priority
 * of individual 'peripheral' interrupts.  If this is the case then a special
 * value will appear in either the crit or main fields indicating a high
 * or medium priority peripheral irq has occurred.
 *
 * This function checks each of the 3 irq request fields and returns the
 * first pending interrupt that it finds.
 *
 * This function also identifies a 4th type of interrupt; 'bestcomm'.  Each
 * bestcomm DMA task can raise the bestcomm peripheral interrupt.  When this
 * occurs at task-specific IRQ# is decoded so that each task can have its
 * own IRQ handler.
 */
unsigned int mpc52xx_get_irq(void)
{
        u32 status;
        int irq;

        status = in_be32(&intr->enc_status);
        if (status & 0x00000400) {      /* critical */
                irq = (status >> 8) & 0x3;
                if (irq == 2)   /* high priority peripheral */
                        goto peripheral;
                irq |= (MPC52xx_IRQ_L1_CRIT << MPC52xx_IRQ_L1_OFFSET);
        } else if (status & 0x00200000) {       /* main */
                irq = (status >> 16) & 0x1f;
                if (irq == 4)   /* low priority peripheral */
                        goto peripheral;
                irq |= (MPC52xx_IRQ_L1_MAIN << MPC52xx_IRQ_L1_OFFSET);
        } else if (status & 0x20000000) {       /* peripheral */
              peripheral:
                irq = (status >> 24) & 0x1f;
                if (irq == 0) { /* bestcomm */
                        status = in_be32(&sdma->IntPend);
                        irq = ffs(status) - 1;
                        irq |= (MPC52xx_IRQ_L1_SDMA << MPC52xx_IRQ_L1_OFFSET);
                } else {
                        irq |= (MPC52xx_IRQ_L1_PERP << MPC52xx_IRQ_L1_OFFSET);
                }
        } else {
                return 0;
        }

        return irq_linear_revmap(mpc52xx_irqhost, irq);
}