/*
 * linux/arch/arm/mach-omap2/cpuidle34xx.c
 *
 * OMAP3 CPU IDLE Routines
 *
 * Copyright (C) 2008 Texas Instruments, Inc.
 * Rajendra Nayak <rnayak@ti.com>
 *
 * Copyright (C) 2007 Texas Instruments, Inc.
 * Karthik Dasu <karthik-dp@ti.com>
 *
 * Copyright (C) 2006 Nokia Corporation
 * Tony Lindgren <tony@atomide.com>
 *
 * Copyright (C) 2005 Texas Instruments, Inc.
 * Richard Woodruff <r-woodruff2@ti.com>
 *
 * Based on pm.c for omap2
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/sched.h>
#include <linux/cpuidle.h>
#include <linux/export.h>
#include <linux/cpu_pm.h>
#include <asm/cpuidle.h>

#include "powerdomain.h"
#include "clockdomain.h"

#include "pm.h"
#include "control.h"
#include "common.h"

/* Mach specific information to be recorded in the C-state driver_data */
struct omap3_idle_statedata {
        u8 mpu_state;
        u8 core_state;
        u8 per_min_state;
        u8 flags;
};

static struct powerdomain *mpu_pd, *core_pd, *per_pd, *cam_pd;

/*
 * Possible flag bits for struct omap3_idle_statedata.flags:
 *
 * OMAP_CPUIDLE_CX_NO_CLKDM_IDLE: don't allow the MPU clockdomain to go
 *    inactive.  This in turn prevents the MPU DPLL from entering autoidle
 *    mode, so wakeup latency is greatly reduced, at the cost of additional
 *    energy consumption.  This also prevents the CORE clockdomain from
 *    entering idle.
 */
#define OMAP_CPUIDLE_CX_NO_CLKDM_IDLE           BIT(0)

/*
 * Prevent PER OFF if CORE is not in RETention or OFF as this would
 * disable PER wakeups completely.
 */
static struct omap3_idle_statedata omap3_idle_data[] = {
        {
                .mpu_state = PWRDM_POWER_ON,
                .core_state = PWRDM_POWER_ON,
                /* In C1 do not allow PER state lower than CORE state */
                .per_min_state = PWRDM_POWER_ON,
                .flags = OMAP_CPUIDLE_CX_NO_CLKDM_IDLE,
        },
        {
                .mpu_state = PWRDM_POWER_ON,
                .core_state = PWRDM_POWER_ON,
                .per_min_state = PWRDM_POWER_RET,
        },
        {
                .mpu_state = PWRDM_POWER_RET,
                .core_state = PWRDM_POWER_ON,
                .per_min_state = PWRDM_POWER_RET,
        },
        {
                .mpu_state = PWRDM_POWER_OFF,
                .core_state = PWRDM_POWER_ON,
                .per_min_state = PWRDM_POWER_RET,
        },
        {
                .mpu_state = PWRDM_POWER_RET,
                .core_state = PWRDM_POWER_RET,
                .per_min_state = PWRDM_POWER_OFF,
        },
        {
                .mpu_state = PWRDM_POWER_OFF,
                .core_state = PWRDM_POWER_RET,
                .per_min_state = PWRDM_POWER_OFF,
        },
        {
                .mpu_state = PWRDM_POWER_OFF,
                .core_state = PWRDM_POWER_OFF,
                .per_min_state = PWRDM_POWER_OFF,
        },
};

/**
 * omap3_enter_idle - Programs OMAP3 to enter the specified state
 * @dev: cpuidle device
 * @drv: cpuidle driver
 * @index: the index of state to be entered
 */
static int omap3_enter_idle(struct cpuidle_device *dev,
                            struct cpuidle_driver *drv,
                            int index)
{
        struct omap3_idle_statedata *cx = &omap3_idle_data[index];

        if (omap_irq_pending() || need_resched())
                goto return_sleep_time;

        /* Deny idle for C1 */
        if (cx->flags & OMAP_CPUIDLE_CX_NO_CLKDM_IDLE) {
                clkdm_deny_idle(mpu_pd->pwrdm_clkdms[0]);
        } else {
                pwrdm_set_next_pwrst(mpu_pd, cx->mpu_state);
                pwrdm_set_next_pwrst(core_pd, cx->core_state);
        }

        /*
         * Call idle CPU PM enter notifier chain so that
         * VFP context is saved.
         */
        if (cx->mpu_state == PWRDM_POWER_OFF)
                cpu_pm_enter();

        /* Execute ARM wfi */
        omap_sram_idle();

        /*
         * Call idle CPU PM enter notifier chain to restore
         * VFP context.
         */
        if (cx->mpu_state == PWRDM_POWER_OFF &&
            pwrdm_read_prev_pwrst(mpu_pd) == PWRDM_POWER_OFF)
                cpu_pm_exit();

        /* Re-allow idle for C1 */
        if (cx->flags & OMAP_CPUIDLE_CX_NO_CLKDM_IDLE)
                clkdm_allow_idle(mpu_pd->pwrdm_clkdms[0]);

return_sleep_time:

        return index;
}

/**
 * next_valid_state - Find next valid C-state
 * @dev: cpuidle device
 * @drv: cpuidle driver
 * @index: Index of currently selected c-state
 *
 * If the state corresponding to index is valid, index is returned back
 * to the caller. Else, this function searches for a lower c-state which is
 * still valid (as defined in omap3_power_states[]) and returns its index.
 *
 * A state is valid if the 'valid' field is enabled and
 * if it satisfies the enable_off_mode condition.
 */
static int next_valid_state(struct cpuidle_device *dev,
                            struct cpuidle_driver *drv, int index)
{
        struct omap3_idle_statedata *cx = &omap3_idle_data[index];
        u32 mpu_deepest_state = PWRDM_POWER_RET;
        u32 core_deepest_state = PWRDM_POWER_RET;
        int idx;
        int next_index = 0; /* C1 is the default value */

        if (enable_off_mode) {
                mpu_deepest_state = PWRDM_POWER_OFF;
                /*
                 * Erratum i583: valable for ES rev < Es1.2 on 3630.
                 * CORE OFF mode is not supported in a stable form, restrict
                 * instead the CORE state to RET.
                 */
                if (!IS_PM34XX_ERRATUM(PM_SDRC_WAKEUP_ERRATUM_i583))
                        core_deepest_state = PWRDM_POWER_OFF;
        }

        /* Check if current state is valid */
        if ((cx->mpu_state >= mpu_deepest_state) &&
            (cx->core_state >= core_deepest_state))
                return index;

        /*
         * Drop to next valid state.
         * Start search from the next (lower) state.
         */
        for (idx = index - 1; idx >= 0; idx--) {
                cx = &omap3_idle_data[idx];
                if ((cx->mpu_state >= mpu_deepest_state) &&
                    (cx->core_state >= core_deepest_state)) {
                        next_index = idx;
                        break;
                }
        }

        return next_index;
}

/**
 * omap3_enter_idle_bm - Checks for any bus activity
 * @dev: cpuidle device
 * @drv: cpuidle driver
 * @index: array index of target state to be programmed
 *
 * This function checks for any pending activity and then programs
 * the device to the specified or a safer state.
 */
static int omap3_enter_idle_bm(struct cpuidle_device *dev,
                               struct cpuidle_driver *drv,
                               int index)
{
        int new_state_idx, ret;
        u8 per_next_state, per_saved_state;
        struct omap3_idle_statedata *cx;

        /*
         * Use only C1 if CAM is active.
         * CAM does not have wakeup capability in OMAP3.
         */
        if (pwrdm_read_pwrst(cam_pd) == PWRDM_POWER_ON)
                new_state_idx = drv->safe_state_index;
        else
                new_state_idx = next_valid_state(dev, drv, index);

        /*
         * FIXME: we currently manage device-specific idle states
         *        for PER and CORE in combination with CPU-specific
         *        idle states.  This is wrong, and device-specific
         *        idle management needs to be separated out into
         *        its own code.
         */

        /* Program PER state */
        cx = &omap3_idle_data[new_state_idx];

        per_next_state = pwrdm_read_next_pwrst(per_pd);
        per_saved_state = per_next_state;
        if (per_next_state < cx->per_min_state) {
                per_next_state = cx->per_min_state;
                pwrdm_set_next_pwrst(per_pd, per_next_state);
        }

        ret = omap3_enter_idle(dev, drv, new_state_idx);

        /* Restore original PER state if it was modified */
        if (per_next_state != per_saved_state)
                pwrdm_set_next_pwrst(per_pd, per_saved_state);

        return ret;
}

static struct cpuidle_driver omap3_idle_driver = {
        .name             = "omap3_idle",
        .owner            = THIS_MODULE,
        .states = {
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 2 + 2,
                        .target_residency = 5,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C1",
                        .desc             = "MPU ON + CORE ON",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 10 + 10,
                        .target_residency = 30,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C2",
                        .desc             = "MPU ON + CORE ON",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 50 + 50,
                        .target_residency = 300,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C3",
                        .desc             = "MPU RET + CORE ON",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 1500 + 1800,
                        .target_residency = 4000,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C4",
                        .desc             = "MPU OFF + CORE ON",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 2500 + 7500,
                        .target_residency = 12000,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C5",
                        .desc             = "MPU RET + CORE RET",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 3000 + 8500,
                        .target_residency = 15000,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C6",
                        .desc             = "MPU OFF + CORE RET",
                },
                {
                        .enter            = omap3_enter_idle_bm,
                        .exit_latency     = 10000 + 30000,
                        .target_residency = 30000,
                        .flags            = CPUIDLE_FLAG_TIME_VALID,
                        .name             = "C7",
                        .desc             = "MPU OFF + CORE OFF",
                },
        },
        .state_count = ARRAY_SIZE(omap3_idle_data),
        .safe_state_index = 0,
};

/* Public functions */

/**
 * omap3_idle_init - Init routine for OMAP3 idle
 *
 * Registers the OMAP3 specific cpuidle driver to the cpuidle
 * framework with the valid set of states.
 */
int __init omap3_idle_init(void)
{
        mpu_pd = pwrdm_lookup("mpu_pwrdm");
        core_pd = pwrdm_lookup("core_pwrdm");
        per_pd = pwrdm_lookup("per_pwrdm");
        cam_pd = pwrdm_lookup("cam_pwrdm");

        if (!mpu_pd || !core_pd || !per_pd || !cam_pd)
                return -ENODEV;

        return cpuidle_register(&omap3_idle_driver, NULL);
}