/*
 *  Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 *  Copyright (C) 2004        John Steele Scott <toojays@toojays.net>
 *
 * 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.
 *
 * TODO: Need a big cleanup here. Basically, we need to have different
 * cpufreq_driver structures for the different type of HW instead of the
 * current mess. We also need to better deal with the detection of the
 * type of machine.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/hardirq.h>
#include <linux/of_device.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/irq.h>
#include <asm/pmac_feature.h>
#include <asm/mmu_context.h>
#include <asm/sections.h>
#include <asm/cputable.h>
#include <asm/time.h>
#include <asm/mpic.h>
#include <asm/keylargo.h>
#include <asm/switch_to.h>

/* WARNING !!! This will cause calibrate_delay() to be called,
 * but this is an __init function ! So you MUST go edit
 * init/main.c to make it non-init before enabling DEBUG_FREQ
 */
#undef DEBUG_FREQ

extern void low_choose_7447a_dfs(int dfs);
extern void low_choose_750fx_pll(int pll);
extern void low_sleep_handler(void);

/*
 * Currently, PowerMac cpufreq supports only high & low frequencies
 * that are set by the firmware
 */
static unsigned int low_freq;
static unsigned int hi_freq;
static unsigned int cur_freq;
static unsigned int sleep_freq;
static unsigned long transition_latency;

/*
 * Different models uses different mechanisms to switch the frequency
 */
static int (*set_speed_proc)(int low_speed);
static unsigned int (*get_speed_proc)(void);

/*
 * Some definitions used by the various speedprocs
 */
static u32 voltage_gpio;
static u32 frequency_gpio;
static u32 slew_done_gpio;
static int no_schedule;
static int has_cpu_l2lve;
static int is_pmu_based;

/* There are only two frequency states for each processor. Values
 * are in kHz for the time being.
 */
#define CPUFREQ_HIGH                  0
#define CPUFREQ_LOW                   1

static struct cpufreq_frequency_table pmac_cpu_freqs[] = {
        {0, CPUFREQ_HIGH,       0},
        {0, CPUFREQ_LOW,        0},
        {0, 0,                  CPUFREQ_TABLE_END},
};

static inline void local_delay(unsigned long ms)
{
        if (no_schedule)
                mdelay(ms);
        else
                msleep(ms);
}

#ifdef DEBUG_FREQ
static inline void debug_calc_bogomips(void)
{
        /* This will cause a recalc of bogomips and display the
         * result. We backup/restore the value to avoid affecting the
         * core cpufreq framework's own calculation.
         */
        unsigned long save_lpj = loops_per_jiffy;
        calibrate_delay();
        loops_per_jiffy = save_lpj;
}
#endif /* DEBUG_FREQ */

/* Switch CPU speed under 750FX CPU control
 */
static int cpu_750fx_cpu_speed(int low_speed)
{
        u32 hid2;

        if (low_speed == 0) {
                /* ramping up, set voltage first */
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x05);
                /* Make sure we sleep for at least 1ms */
                local_delay(10);

                /* tweak L2 for high voltage */
                if (has_cpu_l2lve) {
                        hid2 = mfspr(SPRN_HID2);
                        hid2 &= ~0x2000;
                        mtspr(SPRN_HID2, hid2);
                }
        }
#ifdef CONFIG_6xx
        low_choose_750fx_pll(low_speed);
#endif
        if (low_speed == 1) {
                /* tweak L2 for low voltage */
                if (has_cpu_l2lve) {
                        hid2 = mfspr(SPRN_HID2);
                        hid2 |= 0x2000;
                        mtspr(SPRN_HID2, hid2);
                }

                /* ramping down, set voltage last */
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x04);
                local_delay(10);
        }

        return 0;
}

static unsigned int cpu_750fx_get_cpu_speed(void)
{
        if (mfspr(SPRN_HID1) & HID1_PS)
                return low_freq;
        else
                return hi_freq;
}

/* Switch CPU speed using DFS */
static int dfs_set_cpu_speed(int low_speed)
{
        if (low_speed == 0) {
                /* ramping up, set voltage first */
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x05);
                /* Make sure we sleep for at least 1ms */
                local_delay(1);
        }

        /* set frequency */
#ifdef CONFIG_6xx
        low_choose_7447a_dfs(low_speed);
#endif
        udelay(100);

        if (low_speed == 1) {
                /* ramping down, set voltage last */
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x04);
                local_delay(1);
        }

        return 0;
}

static unsigned int dfs_get_cpu_speed(void)
{
        if (mfspr(SPRN_HID1) & HID1_DFS)
                return low_freq;
        else
                return hi_freq;
}


/* Switch CPU speed using slewing GPIOs
 */
static int gpios_set_cpu_speed(int low_speed)
{
        int gpio, timeout = 0;

        /* If ramping up, set voltage first */
        if (low_speed == 0) {
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x05);
                /* Delay is way too big but it's ok, we schedule */
                local_delay(10);
        }

        /* Set frequency */
        gpio =  pmac_call_feature(PMAC_FTR_READ_GPIO, NULL, frequency_gpio, 0);
        if (low_speed == ((gpio & 0x01) == 0))
                goto skip;

        pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, frequency_gpio,
                          low_speed ? 0x04 : 0x05);
        udelay(200);
        do {
                if (++timeout > 100)
                        break;
                local_delay(1);
                gpio = pmac_call_feature(PMAC_FTR_READ_GPIO, NULL, slew_done_gpio, 0);
        } while((gpio & 0x02) == 0);
 skip:
        /* If ramping down, set voltage last */
        if (low_speed == 1) {
                pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, voltage_gpio, 0x04);
                /* Delay is way too big but it's ok, we schedule */
                local_delay(10);
        }

#ifdef DEBUG_FREQ
        debug_calc_bogomips();
#endif

        return 0;
}

/* Switch CPU speed under PMU control
 */
static int pmu_set_cpu_speed(int low_speed)
{
        struct adb_request req;
        unsigned long save_l2cr;
        unsigned long save_l3cr;
        unsigned int pic_prio;
        unsigned long flags;

        preempt_disable();

#ifdef DEBUG_FREQ
        printk(KERN_DEBUG "HID1, before: %x\n", mfspr(SPRN_HID1));
#endif
        pmu_suspend();

        /* Disable all interrupt sources on openpic */
        pic_prio = mpic_cpu_get_priority();
        mpic_cpu_set_priority(0xf);

        /* Make sure the decrementer won't interrupt us */
        asm volatile("mtdec %0" : : "r" (0x7fffffff));
        /* Make sure any pending DEC interrupt occurring while we did
         * the above didn't re-enable the DEC */
        mb();
        asm volatile("mtdec %0" : : "r" (0x7fffffff));

        /* We can now disable MSR_EE */
        local_irq_save(flags);

        /* Giveup the FPU & vec */
        enable_kernel_fp();

#ifdef CONFIG_ALTIVEC
        if (cpu_has_feature(CPU_FTR_ALTIVEC))
                enable_kernel_altivec();
#endif /* CONFIG_ALTIVEC */

        /* Save & disable L2 and L3 caches */
        save_l3cr = _get_L3CR();        /* (returns -1 if not available) */
        save_l2cr = _get_L2CR();        /* (returns -1 if not available) */

        /* Send the new speed command. My assumption is that this command
         * will cause PLL_CFG[0..3] to be changed next time CPU goes to sleep
         */
        pmu_request(&req, NULL, 6, PMU_CPU_SPEED, 'W', 'O', 'O', 'F', low_speed);
        while (!req.complete)
                pmu_poll();

        /* Prepare the northbridge for the speed transition */
        pmac_call_feature(PMAC_FTR_SLEEP_STATE,NULL,1,1);

        /* Call low level code to backup CPU state and recover from
         * hardware reset
         */
        low_sleep_handler();

        /* Restore the northbridge */
        pmac_call_feature(PMAC_FTR_SLEEP_STATE,NULL,1,0);

        /* Restore L2 cache */
        if (save_l2cr != 0xffffffff && (save_l2cr & L2CR_L2E) != 0)
                _set_L2CR(save_l2cr);
        /* Restore L3 cache */
        if (save_l3cr != 0xffffffff && (save_l3cr & L3CR_L3E) != 0)
                _set_L3CR(save_l3cr);

        /* Restore userland MMU context */
        switch_mmu_context(NULL, current->active_mm, NULL);

#ifdef DEBUG_FREQ
        printk(KERN_DEBUG "HID1, after: %x\n", mfspr(SPRN_HID1));
#endif

        /* Restore low level PMU operations */
        pmu_unlock();

        /*
         * Restore decrementer; we'll take a decrementer interrupt
         * as soon as interrupts are re-enabled and the generic
         * clockevents code will reprogram it with the right value.
         */
        set_dec(1);

        /* Restore interrupts */
        mpic_cpu_set_priority(pic_prio);

        /* Let interrupts flow again ... */
        local_irq_restore(flags);

#ifdef DEBUG_FREQ
        debug_calc_bogomips();
#endif

        pmu_resume();

        preempt_enable();

        return 0;
}

static int do_set_cpu_speed(struct cpufreq_policy *policy, int speed_mode)
{
        unsigned long l3cr;
        static unsigned long prev_l3cr;

        if (speed_mode == CPUFREQ_LOW &&
            cpu_has_feature(CPU_FTR_L3CR)) {
                l3cr = _get_L3CR();
                if (l3cr & L3CR_L3E) {
                        prev_l3cr = l3cr;
                        _set_L3CR(0);
                }
        }
        set_speed_proc(speed_mode == CPUFREQ_LOW);
        if (speed_mode == CPUFREQ_HIGH &&
            cpu_has_feature(CPU_FTR_L3CR)) {
                l3cr = _get_L3CR();
                if ((prev_l3cr & L3CR_L3E) && l3cr != prev_l3cr)
                        _set_L3CR(prev_l3cr);
        }
        cur_freq = (speed_mode == CPUFREQ_HIGH) ? hi_freq : low_freq;

        return 0;
}

static unsigned int pmac_cpufreq_get_speed(unsigned int cpu)
{
        return cur_freq;
}

static int pmac_cpufreq_target( struct cpufreq_policy *policy,
                                        unsigned int index)
{
        int             rc;

        rc = do_set_cpu_speed(policy, index);

        ppc_proc_freq = cur_freq * 1000ul;
        return rc;
}

static int pmac_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
        return cpufreq_generic_init(policy, pmac_cpu_freqs, transition_latency);
}

static u32 read_gpio(struct device_node *np)
{
        const u32 *reg = of_get_property(np, "reg", NULL);
        u32 offset;

        if (reg == NULL)
                return 0;
        /* That works for all keylargos but shall be fixed properly
         * some day... The problem is that it seems we can't rely
         * on the "reg" property of the GPIO nodes, they are either
         * relative to the base of KeyLargo or to the base of the
         * GPIO space, and the device-tree doesn't help.
         */
        offset = *reg;
        if (offset < KEYLARGO_GPIO_LEVELS0)
                offset += KEYLARGO_GPIO_LEVELS0;
        return offset;
}

static int pmac_cpufreq_suspend(struct cpufreq_policy *policy)
{
        /* Ok, this could be made a bit smarter, but let's be robust for now. We
         * always force a speed change to high speed before sleep, to make sure
         * we have appropriate voltage and/or bus speed for the wakeup process,
         * and to make sure our loops_per_jiffies are "good enough", that is will
         * not cause too short delays if we sleep in low speed and wake in high
         * speed..
         */
        no_schedule = 1;
        sleep_freq = cur_freq;
        if (cur_freq == low_freq && !is_pmu_based)
                do_set_cpu_speed(policy, CPUFREQ_HIGH);
        return 0;
}

static int pmac_cpufreq_resume(struct cpufreq_policy *policy)
{
        /* If we resume, first check if we have a get() function */
        if (get_speed_proc)
                cur_freq = get_speed_proc();
        else
                cur_freq = 0;

        /* We don't, hrm... we don't really know our speed here, best
         * is that we force a switch to whatever it was, which is
         * probably high speed due to our suspend() routine
         */
        do_set_cpu_speed(policy, sleep_freq == low_freq ?
                         CPUFREQ_LOW : CPUFREQ_HIGH);

        ppc_proc_freq = cur_freq * 1000ul;

        no_schedule = 0;
        return 0;
}

static struct cpufreq_driver pmac_cpufreq_driver = {
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = pmac_cpufreq_target,
        .get            = pmac_cpufreq_get_speed,
        .init           = pmac_cpufreq_cpu_init,
        .suspend        = pmac_cpufreq_suspend,
        .resume         = pmac_cpufreq_resume,
        .flags          = CPUFREQ_PM_NO_WARN,
        .attr           = cpufreq_generic_attr,
        .name           = "powermac",
};


static int pmac_cpufreq_init_MacRISC3(struct device_node *cpunode)
{
        struct device_node *volt_gpio_np = of_find_node_by_name(NULL,
                                                                "voltage-gpio");
        struct device_node *freq_gpio_np = of_find_node_by_name(NULL,
                                                                "frequency-gpio");
        struct device_node *slew_done_gpio_np = of_find_node_by_name(NULL,
                                                                     "slewing-done");
        const u32 *value;

        /*
         * Check to see if it's GPIO driven or PMU only
         *
         * The way we extract the GPIO address is slightly hackish, but it
         * works well enough for now. We need to abstract the whole GPIO
         * stuff sooner or later anyway
         */

        if (volt_gpio_np)
                voltage_gpio = read_gpio(volt_gpio_np);
        if (freq_gpio_np)
                frequency_gpio = read_gpio(freq_gpio_np);
        if (slew_done_gpio_np)
                slew_done_gpio = read_gpio(slew_done_gpio_np);

        /* If we use the frequency GPIOs, calculate the min/max speeds based
         * on the bus frequencies
         */
        if (frequency_gpio && slew_done_gpio) {
                int lenp, rc;
                const u32 *freqs, *ratio;

                freqs = of_get_property(cpunode, "bus-frequencies", &lenp);
                lenp /= sizeof(u32);
                if (freqs == NULL || lenp != 2) {
                        pr_err("bus-frequencies incorrect or missing\n");
                        return 1;
                }
                ratio = of_get_property(cpunode, "processor-to-bus-ratio*2",
                                                NULL);
                if (ratio == NULL) {
                        pr_err("processor-to-bus-ratio*2 missing\n");
                        return 1;
                }

                /* Get the min/max bus frequencies */
                low_freq = min(freqs[0], freqs[1]);
                hi_freq = max(freqs[0], freqs[1]);

                /* Grrrr.. It _seems_ that the device-tree is lying on the low bus
                 * frequency, it claims it to be around 84Mhz on some models while
                 * it appears to be approx. 101Mhz on all. Let's hack around here...
                 * fortunately, we don't need to be too precise
                 */
                if (low_freq < 98000000)
                        low_freq = 101000000;

                /* Convert those to CPU core clocks */
                low_freq = (low_freq * (*ratio)) / 2000;
                hi_freq = (hi_freq * (*ratio)) / 2000;

                /* Now we get the frequencies, we read the GPIO to see what is out current
                 * speed
                 */
                rc = pmac_call_feature(PMAC_FTR_READ_GPIO, NULL, frequency_gpio, 0);
                cur_freq = (rc & 0x01) ? hi_freq : low_freq;

                set_speed_proc = gpios_set_cpu_speed;
                return 1;
        }

        /* If we use the PMU, look for the min & max frequencies in the
         * device-tree
         */
        value = of_get_property(cpunode, "min-clock-frequency", NULL);
        if (!value)
                return 1;
        low_freq = (*value) / 1000;
        /* The PowerBook G4 12" (PowerBook6,1) has an error in the device-tree
         * here */
        if (low_freq < 100000)
                low_freq *= 10;

        value = of_get_property(cpunode, "max-clock-frequency", NULL);
        if (!value)
                return 1;
        hi_freq = (*value) / 1000;
        set_speed_proc = pmu_set_cpu_speed;
        is_pmu_based = 1;

        return 0;
}

static int pmac_cpufreq_init_7447A(struct device_node *cpunode)
{
        struct device_node *volt_gpio_np;

        if (of_get_property(cpunode, "dynamic-power-step", NULL) == NULL)
                return 1;

        volt_gpio_np = of_find_node_by_name(NULL, "cpu-vcore-select");
        if (volt_gpio_np)
                voltage_gpio = read_gpio(volt_gpio_np);
        if (!voltage_gpio){
                pr_err("missing cpu-vcore-select gpio\n");
                return 1;
        }

        /* OF only reports the high frequency */
        hi_freq = cur_freq;
        low_freq = cur_freq/2;

        /* Read actual frequency from CPU */
        cur_freq = dfs_get_cpu_speed();
        set_speed_proc = dfs_set_cpu_speed;
        get_speed_proc = dfs_get_cpu_speed;

        return 0;
}

static int pmac_cpufreq_init_750FX(struct device_node *cpunode)
{
        struct device_node *volt_gpio_np;
        u32 pvr;
        const u32 *value;

        if (of_get_property(cpunode, "dynamic-power-step", NULL) == NULL)
                return 1;

        hi_freq = cur_freq;
        value = of_get_property(cpunode, "reduced-clock-frequency", NULL);
        if (!value)
                return 1;
        low_freq = (*value) / 1000;

        volt_gpio_np = of_find_node_by_name(NULL, "cpu-vcore-select");
        if (volt_gpio_np)
                voltage_gpio = read_gpio(volt_gpio_np);

        pvr = mfspr(SPRN_PVR);
        has_cpu_l2lve = !((pvr & 0xf00) == 0x100);

        set_speed_proc = cpu_750fx_cpu_speed;
        get_speed_proc = cpu_750fx_get_cpu_speed;
        cur_freq = cpu_750fx_get_cpu_speed();

        return 0;
}

/* Currently, we support the following machines:
 *
 *  - Titanium PowerBook 1Ghz (PMU based, 667Mhz & 1Ghz)
 *  - Titanium PowerBook 800 (PMU based, 667Mhz & 800Mhz)
 *  - Titanium PowerBook 400 (PMU based, 300Mhz & 400Mhz)
 *  - Titanium PowerBook 500 (PMU based, 300Mhz & 500Mhz)
 *  - iBook2 500/600 (PMU based, 400Mhz & 500/600Mhz)
 *  - iBook2 700 (CPU based, 400Mhz & 700Mhz, support low voltage)
 *  - Recent MacRISC3 laptops
 *  - All new machines with 7447A CPUs
 */
static int __init pmac_cpufreq_setup(void)
{
        struct device_node      *cpunode;
        const u32               *value;

        if (strstr(boot_command_line, "nocpufreq"))
                return 0;

        /* Get first CPU node */
        cpunode = of_cpu_device_node_get(0);
        if (!cpunode)
                goto out;

        /* Get current cpu clock freq */
        value = of_get_property(cpunode, "clock-frequency", NULL);
        if (!value)
                goto out;
        cur_freq = (*value) / 1000;
        transition_latency = CPUFREQ_ETERNAL;

        /*  Check for 7447A based MacRISC3 */
        if (of_machine_is_compatible("MacRISC3") &&
            of_get_property(cpunode, "dynamic-power-step", NULL) &&
            PVR_VER(mfspr(SPRN_PVR)) == 0x8003) {
                pmac_cpufreq_init_7447A(cpunode);
                transition_latency = 8000000;
        /* Check for other MacRISC3 machines */
        } else if (of_machine_is_compatible("PowerBook3,4") ||
                   of_machine_is_compatible("PowerBook3,5") ||
                   of_machine_is_compatible("MacRISC3")) {
                pmac_cpufreq_init_MacRISC3(cpunode);
        /* Else check for iBook2 500/600 */
        } else if (of_machine_is_compatible("PowerBook4,1")) {
                hi_freq = cur_freq;
                low_freq = 400000;
                set_speed_proc = pmu_set_cpu_speed;
                is_pmu_based = 1;
        }
        /* Else check for TiPb 550 */
        else if (of_machine_is_compatible("PowerBook3,3") && cur_freq == 550000) {
                hi_freq = cur_freq;
                low_freq = 500000;
                set_speed_proc = pmu_set_cpu_speed;
                is_pmu_based = 1;
        }
        /* Else check for TiPb 400 & 500 */
        else if (of_machine_is_compatible("PowerBook3,2")) {
                /* We only know about the 400 MHz and the 500Mhz model
                 * they both have 300 MHz as low frequency
                 */
                if (cur_freq < 350000 || cur_freq > 550000)
                        goto out;
                hi_freq = cur_freq;
                low_freq = 300000;
                set_speed_proc = pmu_set_cpu_speed;
                is_pmu_based = 1;
        }
        /* Else check for 750FX */
        else if (PVR_VER(mfspr(SPRN_PVR)) == 0x7000)
                pmac_cpufreq_init_750FX(cpunode);
out:
        of_node_put(cpunode);
        if (set_speed_proc == NULL)
                return -ENODEV;

        pmac_cpu_freqs[CPUFREQ_LOW].frequency = low_freq;
        pmac_cpu_freqs[CPUFREQ_HIGH].frequency = hi_freq;
        ppc_proc_freq = cur_freq * 1000ul;

        pr_info("Registering PowerMac CPU frequency driver\n");
        pr_info("Low: %d Mhz, High: %d Mhz, Boot: %d Mhz\n",
                low_freq/1000, hi_freq/1000, cur_freq/1000);

        return cpufreq_register_driver(&pmac_cpufreq_driver);
}

module_init(pmac_cpufreq_setup);