/*
 * twl4030-irq.c - TWL4030/TPS659x0 irq support
 *
 * Copyright (C) 2005-2006 Texas Instruments, Inc.
 *
 * Modifications to defer interrupt handling to a kernel thread:
 * Copyright (C) 2006 MontaVista Software, Inc.
 *
 * Based on tlv320aic23.c:
 * Copyright (c) by Kai Svahn <kai.svahn@nokia.com>
 *
 * Code cleanup and modifications to IRQ handler.
 * by syed khasim <x0khasim@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kthread.h>

#include <linux/i2c/twl4030.h>


/*
 * TWL4030 IRQ handling has two stages in hardware, and thus in software.
 * The Primary Interrupt Handler (PIH) stage exposes status bits saying
 * which Secondary Interrupt Handler (SIH) stage is raising an interrupt.
 * SIH modules are more traditional IRQ components, which support per-IRQ
 * enable/disable and trigger controls; they do most of the work.
 *
 * These chips are designed to support IRQ handling from two different
 * I2C masters.  Each has a dedicated IRQ line, and dedicated IRQ status
 * and mask registers in the PIH and SIH modules.
 *
 * We set up IRQs starting at a platform-specified base, always starting
 * with PIH and the SIH for PWR_INT and then usually adding GPIO:
 *      base + 0  .. base + 7   PIH
 *      base + 8  .. base + 15  SIH for PWR_INT
 *      base + 16 .. base + 33  SIH for GPIO
 */

/* PIH register offsets */
#define REG_PIH_ISR_P1                  0x01
#define REG_PIH_ISR_P2                  0x02
#define REG_PIH_SIR                     0x03    /* for testing */


/* Linux could (eventually) use either IRQ line */
static int irq_line;

struct sih {
        char    name[8];
        u8      module;                 /* module id */
        u8      control_offset;         /* for SIH_CTRL */
        bool    set_cor;

        u8      bits;                   /* valid in isr/imr */
        u8      bytes_ixr;              /* bytelen of ISR/IMR/SIR */

        u8      edr_offset;
        u8      bytes_edr;              /* bytelen of EDR */

        /* SIR ignored -- set interrupt, for testing only */
        struct irq_data {
                u8      isr_offset;
                u8      imr_offset;
        } mask[2];
        /* + 2 bytes padding */
};

#define SIH_INITIALIZER(modname, nbits) \
        .module         = TWL4030_MODULE_ ## modname, \
        .control_offset = TWL4030_ ## modname ## _SIH_CTRL, \
        .bits           = nbits, \
        .bytes_ixr      = DIV_ROUND_UP(nbits, 8), \
        .edr_offset     = TWL4030_ ## modname ## _EDR, \
        .bytes_edr      = DIV_ROUND_UP((2*(nbits)), 8), \
        .mask = { { \
                .isr_offset     = TWL4030_ ## modname ## _ISR1, \
                .imr_offset     = TWL4030_ ## modname ## _IMR1, \
        }, \
        { \
                .isr_offset     = TWL4030_ ## modname ## _ISR2, \
                .imr_offset     = TWL4030_ ## modname ## _IMR2, \
        }, },

/* register naming policies are inconsistent ... */
#define TWL4030_INT_PWR_EDR             TWL4030_INT_PWR_EDR1
#define TWL4030_MODULE_KEYPAD_KEYP      TWL4030_MODULE_KEYPAD
#define TWL4030_MODULE_INT_PWR          TWL4030_MODULE_INT


/* Order in this table matches order in PIH_ISR.  That is,
 * BIT(n) in PIH_ISR is sih_modules[n].
 */
static const struct sih sih_modules[6] = {
        [0] = {
                .name           = "gpio",
                .module         = TWL4030_MODULE_GPIO,
                .control_offset = REG_GPIO_SIH_CTRL,
                .set_cor        = true,
                .bits           = TWL4030_GPIO_MAX,
                .bytes_ixr      = 3,
                /* Note: *all* of these IRQs default to no-trigger */
                .edr_offset     = REG_GPIO_EDR1,
                .bytes_edr      = 5,
                .mask = { {
                        .isr_offset     = REG_GPIO_ISR1A,
                        .imr_offset     = REG_GPIO_IMR1A,
                }, {
                        .isr_offset     = REG_GPIO_ISR1B,
                        .imr_offset     = REG_GPIO_IMR1B,
                }, },
        },
        [1] = {
                .name           = "keypad",
                .set_cor        = true,
                SIH_INITIALIZER(KEYPAD_KEYP, 4)
        },
        [2] = {
                .name           = "bci",
                .module         = TWL4030_MODULE_INTERRUPTS,
                .control_offset = TWL4030_INTERRUPTS_BCISIHCTRL,
                .bits           = 12,
                .bytes_ixr      = 2,
                .edr_offset     = TWL4030_INTERRUPTS_BCIEDR1,
                /* Note: most of these IRQs default to no-trigger */
                .bytes_edr      = 3,
                .mask = { {
                        .isr_offset     = TWL4030_INTERRUPTS_BCIISR1A,
                        .imr_offset     = TWL4030_INTERRUPTS_BCIIMR1A,
                }, {
                        .isr_offset     = TWL4030_INTERRUPTS_BCIISR1B,
                        .imr_offset     = TWL4030_INTERRUPTS_BCIIMR1B,
                }, },
        },
        [3] = {
                .name           = "madc",
                SIH_INITIALIZER(MADC, 4)
        },
        [4] = {
                /* USB doesn't use the same SIH organization */
                .name           = "usb",
        },
        [5] = {
                .name           = "power",
                .set_cor        = true,
                SIH_INITIALIZER(INT_PWR, 8)
        },
                /* there are no SIH modules #6 or #7 ... */
};

#undef TWL4030_MODULE_KEYPAD_KEYP
#undef TWL4030_MODULE_INT_PWR
#undef TWL4030_INT_PWR_EDR

/*----------------------------------------------------------------------*/

static unsigned twl4030_irq_base;

static struct completion irq_event;

/*
 * This thread processes interrupts reported by the Primary Interrupt Handler.
 */
static int twl4030_irq_thread(void *data)
{
        long irq = (long)data;
        static unsigned i2c_errors;
        static const unsigned max_i2c_errors = 100;


        current->flags |= PF_NOFREEZE;

        while (!kthread_should_stop()) {
                int ret;
                int module_irq;
                u8 pih_isr;

                /* Wait for IRQ, then read PIH irq status (also blocking) */
                wait_for_completion_interruptible(&irq_event);

                ret = twl4030_i2c_read_u8(TWL4030_MODULE_PIH, &pih_isr,
                                          REG_PIH_ISR_P1);
                if (ret) {
                        pr_warning("twl4030: I2C error %d reading PIH ISR\n",
                                        ret);
                        if (++i2c_errors >= max_i2c_errors) {
                                printk(KERN_ERR "Maximum I2C error count"
                                                " exceeded.  Terminating %s.\n",
                                                __func__);
                                break;
                        }
                        complete(&irq_event);
                        continue;
                }

                /* these handlers deal with the relevant SIH irq status */
                local_irq_disable();
                for (module_irq = twl4030_irq_base;
                                pih_isr;
                                pih_isr >>= 1, module_irq++) {
                        if (pih_isr & 0x1) {
                                struct irq_desc *d = irq_to_desc(module_irq);

                                if (!d) {
                                        pr_err("twl4030: Invalid SIH IRQ: %d\n",
                                               module_irq);
                                        return -EINVAL;
                                }

                                /* These can't be masked ... always warn
                                 * if we get any surprises.
                                 */
                                if (d->status & IRQ_DISABLED)
                                        note_interrupt(module_irq, d,
                                                        IRQ_NONE);
                                else
                                        d->handle_irq(module_irq, d);
                        }
                }
                local_irq_enable();

                enable_irq(irq);
        }

        return 0;
}

/*
 * handle_twl4030_pih() is the desc->handle method for the twl4030 interrupt.
 * This is a chained interrupt, so there is no desc->action method for it.
 * Now we need to query the interrupt controller in the twl4030 to determine
 * which module is generating the interrupt request.  However, we can't do i2c
 * transactions in interrupt context, so we must defer that work to a kernel
 * thread.  All we do here is acknowledge and mask the interrupt and wakeup
 * the kernel thread.
 */
static irqreturn_t handle_twl4030_pih(int irq, void *devid)
{
        /* Acknowledge, clear *AND* mask the interrupt... */
        disable_irq_nosync(irq);
        complete(devid);
        return IRQ_HANDLED;
}
/*----------------------------------------------------------------------*/

/*
 * twl4030_init_sih_modules() ... start from a known state where no
 * IRQs will be coming in, and where we can quickly enable them then
 * handle them as they arrive.  Mask all IRQs: maybe init SIH_CTRL.
 *
 * NOTE:  we don't touch EDR registers here; they stay with hardware
 * defaults or whatever the last value was.  Note that when both EDR
 * bits for an IRQ are clear, that's as if its IMR bit is set...
 */
static int twl4030_init_sih_modules(unsigned line)
{
        const struct sih *sih;
        u8 buf[4];
        int i;
        int status;

        /* line 0 == int1_n signal; line 1 == int2_n signal */
        if (line > 1)
                return -EINVAL;

        irq_line = line;

        /* disable all interrupts on our line */
        memset(buf, 0xff, sizeof buf);
        sih = sih_modules;
        for (i = 0; i < ARRAY_SIZE(sih_modules); i++, sih++) {

                /* skip USB -- it's funky */
                if (!sih->bytes_ixr)
                        continue;

                status = twl4030_i2c_write(sih->module, buf,
                                sih->mask[line].imr_offset, sih->bytes_ixr);
                if (status < 0)
                        pr_err("twl4030: err %d initializing %s %s\n",
                                        status, sih->name, "IMR");

                /* Maybe disable "exclusive" mode; buffer second pending irq;
                 * set Clear-On-Read (COR) bit.
                 *
                 * NOTE that sometimes COR polarity is documented as being
                 * inverted:  for MADC and BCI, COR=1 means "clear on write".
                 * And for PWR_INT it's not documented...
                 */
                if (sih->set_cor) {
                        status = twl4030_i2c_write_u8(sih->module,
                                        TWL4030_SIH_CTRL_COR_MASK,
                                        sih->control_offset);
                        if (status < 0)
                                pr_err("twl4030: err %d initializing %s %s\n",
                                                status, sih->name, "SIH_CTRL");
                }
        }

        sih = sih_modules;
        for (i = 0; i < ARRAY_SIZE(sih_modules); i++, sih++) {
                u8 rxbuf[4];
                int j;

                /* skip USB */
                if (!sih->bytes_ixr)
                        continue;

                /* Clear pending interrupt status.  Either the read was
                 * enough, or we need to write those bits.  Repeat, in
                 * case an IRQ is pending (PENDDIS=0) ... that's not
                 * uncommon with PWR_INT.PWRON.
                 */
                for (j = 0; j < 2; j++) {
                        status = twl4030_i2c_read(sih->module, rxbuf,
                                sih->mask[line].isr_offset, sih->bytes_ixr);
                        if (status < 0)
                                pr_err("twl4030: err %d initializing %s %s\n",
                                        status, sih->name, "ISR");

                        if (!sih->set_cor)
                                status = twl4030_i2c_write(sih->module, buf,
                                        sih->mask[line].isr_offset,
                                        sih->bytes_ixr);
                        /* else COR=1 means read sufficed.
                         * (for most SIH modules...)
                         */
                }
        }

        return 0;
}

static inline void activate_irq(int irq)
{
#ifdef CONFIG_ARM
        /* ARM requires an extra step to clear IRQ_NOREQUEST, which it
         * sets on behalf of every irq_chip.  Also sets IRQ_NOPROBE.
         */
        set_irq_flags(irq, IRQF_VALID);
#else
        /* same effect on other architectures */
        set_irq_noprobe(irq);
#endif
}

/*----------------------------------------------------------------------*/

static DEFINE_SPINLOCK(sih_agent_lock);

static struct workqueue_struct *wq;

struct sih_agent {
        int                     irq_base;
        const struct sih        *sih;

        u32                     imr;
        bool                    imr_change_pending;
        struct work_struct      mask_work;

        u32                     edge_change;
        struct work_struct      edge_work;
};

static void twl4030_sih_do_mask(struct work_struct *work)
{
        struct sih_agent        *agent;
        const struct sih        *sih;
        union {
                u8      bytes[4];
                u32     word;
        }                       imr;
        int                     status;

        agent = container_of(work, struct sih_agent, mask_work);

        /* see what work we have */
        spin_lock_irq(&sih_agent_lock);
        if (agent->imr_change_pending) {
                sih = agent->sih;
                /* byte[0] gets overwritten as we write ... */
                imr.word = cpu_to_le32(agent->imr << 8);
                agent->imr_change_pending = false;
        } else
                sih = NULL;
        spin_unlock_irq(&sih_agent_lock);
        if (!sih)
                return;

        /* write the whole mask ... simpler than subsetting it */
        status = twl4030_i2c_write(sih->module, imr.bytes,
                        sih->mask[irq_line].imr_offset, sih->bytes_ixr);
        if (status)
                pr_err("twl4030: %s, %s --> %d\n", __func__,
                                "write", status);
}

static void twl4030_sih_do_edge(struct work_struct *work)
{
        struct sih_agent        *agent;
        const struct sih        *sih;
        u8                      bytes[6];
        u32                     edge_change;
        int                     status;

        agent = container_of(work, struct sih_agent, edge_work);

        /* see what work we have */
        spin_lock_irq(&sih_agent_lock);
        edge_change = agent->edge_change;
        agent->edge_change = 0;
        sih = edge_change ? agent->sih : NULL;
        spin_unlock_irq(&sih_agent_lock);
        if (!sih)
                return;

        /* Read, reserving first byte for write scratch.  Yes, this
         * could be cached for some speedup ... but be careful about
         * any processor on the other IRQ line, EDR registers are
         * shared.
         */
        status = twl4030_i2c_read(sih->module, bytes + 1,
                        sih->edr_offset, sih->bytes_edr);
        if (status) {
                pr_err("twl4030: %s, %s --> %d\n", __func__,
                                "read", status);
                return;
        }

        /* Modify only the bits we know must change */
        while (edge_change) {
                int             i = fls(edge_change) - 1;
                struct irq_desc *d = irq_to_desc(i + agent->irq_base);
                int             byte = 1 + (i >> 2);
                int             off = (i & 0x3) * 2;

                if (!d) {
                        pr_err("twl4030: Invalid IRQ: %d\n",
                               i + agent->irq_base);
                        return;
                }

                bytes[byte] &= ~(0x03 << off);

                spin_lock_irq(&d->lock);
                if (d->status & IRQ_TYPE_EDGE_RISING)
                        bytes[byte] |= BIT(off + 1);
                if (d->status & IRQ_TYPE_EDGE_FALLING)
                        bytes[byte] |= BIT(off + 0);
                spin_unlock_irq(&d->lock);

                edge_change &= ~BIT(i);
        }

        /* Write */
        status = twl4030_i2c_write(sih->module, bytes,
                        sih->edr_offset, sih->bytes_edr);
        if (status)
                pr_err("twl4030: %s, %s --> %d\n", __func__,
                                "write", status);
}

/*----------------------------------------------------------------------*/

/*
 * All irq_chip methods get issued from code holding irq_desc[irq].lock,
 * which can't perform the underlying I2C operations (because they sleep).
 * So we must hand them off to a thread (workqueue) and cope with asynch
 * completion, potentially including some re-ordering, of these requests.
 */

static void twl4030_sih_mask(unsigned irq)
{
        struct sih_agent *sih = get_irq_chip_data(irq);
        unsigned long flags;

        spin_lock_irqsave(&sih_agent_lock, flags);
        sih->imr |= BIT(irq - sih->irq_base);
        sih->imr_change_pending = true;
        queue_work(wq, &sih->mask_work);
        spin_unlock_irqrestore(&sih_agent_lock, flags);
}

static void twl4030_sih_unmask(unsigned irq)
{
        struct sih_agent *sih = get_irq_chip_data(irq);
        unsigned long flags;

        spin_lock_irqsave(&sih_agent_lock, flags);
        sih->imr &= ~BIT(irq - sih->irq_base);
        sih->imr_change_pending = true;
        queue_work(wq, &sih->mask_work);
        spin_unlock_irqrestore(&sih_agent_lock, flags);
}

static int twl4030_sih_set_type(unsigned irq, unsigned trigger)
{
        struct sih_agent *sih = get_irq_chip_data(irq);
        struct irq_desc *desc = irq_to_desc(irq);
        unsigned long flags;

        if (!desc) {
                pr_err("twl4030: Invalid IRQ: %d\n", irq);
                return -EINVAL;
        }

        if (trigger & ~(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
                return -EINVAL;

        spin_lock_irqsave(&sih_agent_lock, flags);
        if ((desc->status & IRQ_TYPE_SENSE_MASK) != trigger) {
                desc->status &= ~IRQ_TYPE_SENSE_MASK;
                desc->status |= trigger;
                sih->edge_change |= BIT(irq - sih->irq_base);
                queue_work(wq, &sih->edge_work);
        }
        spin_unlock_irqrestore(&sih_agent_lock, flags);
        return 0;
}

static struct irq_chip twl4030_sih_irq_chip = {
        .name           = "twl4030",
        .mask           = twl4030_sih_mask,
        .unmask         = twl4030_sih_unmask,
        .set_type       = twl4030_sih_set_type,
};

/*----------------------------------------------------------------------*/

static inline int sih_read_isr(const struct sih *sih)
{
        int status;
        union {
                u8 bytes[4];
                u32 word;
        } isr;

        /* FIXME need retry-on-error ... */

        isr.word = 0;
        status = twl4030_i2c_read(sih->module, isr.bytes,
                        sih->mask[irq_line].isr_offset, sih->bytes_ixr);

        return (status < 0) ? status : le32_to_cpu(isr.word);
}

/*
 * Generic handler for SIH interrupts ... we "know" this is called
 * in task context, with IRQs enabled.
 */
static void handle_twl4030_sih(unsigned irq, struct irq_desc *desc)
{
        struct sih_agent *agent = get_irq_data(irq);
        const struct sih *sih = agent->sih;
        int isr;

        /* reading ISR acks the IRQs, using clear-on-read mode */
        local_irq_enable();
        isr = sih_read_isr(sih);
        local_irq_disable();

        if (isr < 0) {
                pr_err("twl4030: %s SIH, read ISR error %d\n",
                        sih->name, isr);
                /* REVISIT:  recover; eventually mask it all, etc */
                return;
        }

        while (isr) {
                irq = fls(isr);
                irq--;
                isr &= ~BIT(irq);

                if (irq < sih->bits)
                        generic_handle_irq(agent->irq_base + irq);
                else
                        pr_err("twl4030: %s SIH, invalid ISR bit %d\n",
                                sih->name, irq);
        }
}

static unsigned twl4030_irq_next;

/* returns the first IRQ used by this SIH bank,
 * or negative errno
 */
int twl4030_sih_setup(int module)
{
        int                     sih_mod;
        const struct sih        *sih = NULL;
        struct sih_agent        *agent;
        int                     i, irq;
        int                     status = -EINVAL;
        unsigned                irq_base = twl4030_irq_next;

        /* only support modules with standard clear-on-read for now */
        for (sih_mod = 0, sih = sih_modules;
                        sih_mod < ARRAY_SIZE(sih_modules);
                        sih_mod++, sih++) {
                if (sih->module == module && sih->set_cor) {
                        if (!WARN((irq_base + sih->bits) > NR_IRQS,
                                        "irq %d for %s too big\n",
                                        irq_base + sih->bits,
                                        sih->name))
                                status = 0;
                        break;
                }
        }
        if (status < 0)
                return status;

        agent = kzalloc(sizeof *agent, GFP_KERNEL);
        if (!agent)
                return -ENOMEM;

        status = 0;

        agent->irq_base = irq_base;
        agent->sih = sih;
        agent->imr = ~0;
        INIT_WORK(&agent->mask_work, twl4030_sih_do_mask);
        INIT_WORK(&agent->edge_work, twl4030_sih_do_edge);

        for (i = 0; i < sih->bits; i++) {
                irq = irq_base + i;

                set_irq_chip_and_handler(irq, &twl4030_sih_irq_chip,
                                handle_edge_irq);
                set_irq_chip_data(irq, agent);
                activate_irq(irq);
        }

        status = irq_base;
        twl4030_irq_next += i;

        /* replace generic PIH handler (handle_simple_irq) */
        irq = sih_mod + twl4030_irq_base;
        set_irq_data(irq, agent);
        set_irq_chained_handler(irq, handle_twl4030_sih);

        pr_info("twl4030: %s (irq %d) chaining IRQs %d..%d\n", sih->name,
                        irq, irq_base, twl4030_irq_next - 1);

        return status;
}

/* FIXME need a call to reverse twl4030_sih_setup() ... */


/*----------------------------------------------------------------------*/

/* FIXME pass in which interrupt line we'll use ... */
#define twl_irq_line    0

int twl_init_irq(int irq_num, unsigned irq_base, unsigned irq_end)
{
        static struct irq_chip  twl4030_irq_chip;

        int                     status;
        int                     i;
        struct task_struct      *task;

        /*
         * Mask and clear all TWL4030 interrupts since initially we do
         * not have any TWL4030 module interrupt handlers present
         */
        status = twl4030_init_sih_modules(twl_irq_line);
        if (status < 0)
                return status;

        wq = create_singlethread_workqueue("twl4030-irqchip");
        if (!wq) {
                pr_err("twl4030: workqueue FAIL\n");
                return -ESRCH;
        }

        twl4030_irq_base = irq_base;

        /* install an irq handler for each of the SIH modules;
         * clone dummy irq_chip since PIH can't *do* anything
         */
        twl4030_irq_chip = dummy_irq_chip;
        twl4030_irq_chip.name = "twl4030";

        twl4030_sih_irq_chip.ack = dummy_irq_chip.ack;

        for (i = irq_base; i < irq_end; i++) {
                set_irq_chip_and_handler(i, &twl4030_irq_chip,
                                handle_simple_irq);
                activate_irq(i);
        }
        twl4030_irq_next = i;
        pr_info("twl4030: %s (irq %d) chaining IRQs %d..%d\n", "PIH",
                        irq_num, irq_base, twl4030_irq_next - 1);

        /* ... and the PWR_INT module ... */
        status = twl4030_sih_setup(TWL4030_MODULE_INT);
        if (status < 0) {
                pr_err("twl4030: sih_setup PWR INT --> %d\n", status);
                goto fail;
        }

        /* install an irq handler to demultiplex the TWL4030 interrupt */


        init_completion(&irq_event);

        status = request_irq(irq_num, handle_twl4030_pih, IRQF_DISABLED,
                                "TWL4030-PIH", &irq_event);
        if (status < 0) {
                pr_err("twl4030: could not claim irq%d: %d\n", irq_num, status);
                goto fail_rqirq;
        }

        task = kthread_run(twl4030_irq_thread, (void *)irq_num, "twl4030-irq");
        if (IS_ERR(task)) {
                pr_err("twl4030: could not create irq %d thread!\n", irq_num);
                status = PTR_ERR(task);
                goto fail_kthread;
        }
        return status;
fail_kthread:
        free_irq(irq_num, &irq_event);
fail_rqirq:
        /* clean up twl4030_sih_setup */
fail:
        for (i = irq_base; i < irq_end; i++)
                set_irq_chip_and_handler(i, NULL, NULL);
        destroy_workqueue(wq);
        wq = NULL;
        return status;
}

int twl_exit_irq(void)
{
        /* FIXME undo twl_init_irq() */
        if (twl4030_irq_base) {
                pr_err("twl4030: can't yet clean up IRQs?\n");
                return -ENOSYS;
        }
        return 0;
}