/*
 * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
 *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 *                      - Added processor hotplug support
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sysdev.h>

#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#include <acpi/acpi_drivers.h>

#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_thermal");

/* --------------------------------------------------------------------------
                                 Limit Interface
   -------------------------------------------------------------------------- */
static int acpi_processor_apply_limit(struct acpi_processor *pr)
{
        int result = 0;
        u16 px = 0;
        u16 tx = 0;


        if (!pr)
                return -EINVAL;

        if (!pr->flags.limit)
                return -ENODEV;

        if (pr->flags.throttling) {
                if (pr->limit.user.tx > tx)
                        tx = pr->limit.user.tx;
                if (pr->limit.thermal.tx > tx)
                        tx = pr->limit.thermal.tx;

                result = acpi_processor_set_throttling(pr, tx);
                if (result)
                        goto end;
        }

        pr->limit.state.px = px;
        pr->limit.state.tx = tx;

        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                          "Processor [%d] limit set to (P%d:T%d)\n", pr->id,
                          pr->limit.state.px, pr->limit.state.tx));

      end:
        if (result)
                printk(KERN_ERR PREFIX "Unable to set limit\n");

        return result;
}

#ifdef CONFIG_CPU_FREQ

/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
 * offers (in most cases) voltage scaling in addition to frequency scaling, and
 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
 */

#define CPUFREQ_THERMAL_MIN_STEP 0
#define CPUFREQ_THERMAL_MAX_STEP 3

static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
static unsigned int acpi_thermal_cpufreq_is_init = 0;

static int cpu_has_cpufreq(unsigned int cpu)
{
        struct cpufreq_policy policy;
        if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
                return 0;
        return 1;
}

static int acpi_thermal_cpufreq_increase(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return -ENODEV;

        if (per_cpu(cpufreq_thermal_reduction_pctg, cpu) <
                CPUFREQ_THERMAL_MAX_STEP) {
                per_cpu(cpufreq_thermal_reduction_pctg, cpu)++;
                cpufreq_update_policy(cpu);
                return 0;
        }

        return -ERANGE;
}

static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return -ENODEV;

        if (per_cpu(cpufreq_thermal_reduction_pctg, cpu) >
                (CPUFREQ_THERMAL_MIN_STEP + 1))
                per_cpu(cpufreq_thermal_reduction_pctg, cpu)--;
        else
                per_cpu(cpufreq_thermal_reduction_pctg, cpu) = 0;
        cpufreq_update_policy(cpu);
        /* We reached max freq again and can leave passive mode */
        return !per_cpu(cpufreq_thermal_reduction_pctg, cpu);
}

static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
                                         unsigned long event, void *data)
{
        struct cpufreq_policy *policy = data;
        unsigned long max_freq = 0;

        if (event != CPUFREQ_ADJUST)
                goto out;

        max_freq = (
            policy->cpuinfo.max_freq *
            (100 - per_cpu(cpufreq_thermal_reduction_pctg, policy->cpu) * 20)
        ) / 100;

        cpufreq_verify_within_limits(policy, 0, max_freq);

      out:
        return 0;
}

static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
        .notifier_call = acpi_thermal_cpufreq_notifier,
};

static int cpufreq_get_max_state(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return 0;

        return CPUFREQ_THERMAL_MAX_STEP;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return 0;

        return per_cpu(cpufreq_thermal_reduction_pctg, cpu);
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
        if (!cpu_has_cpufreq(cpu))
                return 0;

        per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
        cpufreq_update_policy(cpu);
        return 0;
}

void acpi_thermal_cpufreq_init(void)
{
        int i;

        for (i = 0; i < nr_cpu_ids; i++)
                if (cpu_present(i))
                        per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;

        i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
                                      CPUFREQ_POLICY_NOTIFIER);
        if (!i)
                acpi_thermal_cpufreq_is_init = 1;
}

void acpi_thermal_cpufreq_exit(void)
{
        if (acpi_thermal_cpufreq_is_init)
                cpufreq_unregister_notifier
                    (&acpi_thermal_cpufreq_notifier_block,
                     CPUFREQ_POLICY_NOTIFIER);

        acpi_thermal_cpufreq_is_init = 0;
}

#else                           /* ! CONFIG_CPU_FREQ */
static int cpufreq_get_max_state(unsigned int cpu)
{
        return 0;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
        return 0;
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
        return 0;
}

static int acpi_thermal_cpufreq_increase(unsigned int cpu)
{
        return -ENODEV;
}
static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
{
        return -ENODEV;
}

#endif

int acpi_processor_set_thermal_limit(acpi_handle handle, int type)
{
        int result = 0;
        struct acpi_processor *pr = NULL;
        struct acpi_device *device = NULL;
        int tx = 0, max_tx_px = 0;


        if ((type < ACPI_PROCESSOR_LIMIT_NONE)
            || (type > ACPI_PROCESSOR_LIMIT_DECREMENT))
                return -EINVAL;

        result = acpi_bus_get_device(handle, &device);
        if (result)
                return result;

        pr = acpi_driver_data(device);
        if (!pr)
                return -ENODEV;

        /* Thermal limits are always relative to the current Px/Tx state. */
        if (pr->flags.throttling)
                pr->limit.thermal.tx = pr->throttling.state;

        /*
         * Our default policy is to only use throttling at the lowest
         * performance state.
         */

        tx = pr->limit.thermal.tx;

        switch (type) {

        case ACPI_PROCESSOR_LIMIT_NONE:
                do {
                        result = acpi_thermal_cpufreq_decrease(pr->id);
                } while (!result);
                tx = 0;
                break;

        case ACPI_PROCESSOR_LIMIT_INCREMENT:
                /* if going up: P-states first, T-states later */

                result = acpi_thermal_cpufreq_increase(pr->id);
                if (!result)
                        goto end;
                else if (result == -ERANGE)
                        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                          "At maximum performance state\n"));

                if (pr->flags.throttling) {
                        if (tx == (pr->throttling.state_count - 1))
                                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                                  "At maximum throttling state\n"));
                        else
                                tx++;
                }
                break;

        case ACPI_PROCESSOR_LIMIT_DECREMENT:
                /* if going down: T-states first, P-states later */

                if (pr->flags.throttling) {
                        if (tx == 0) {
                                max_tx_px = 1;
                                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                                  "At minimum throttling state\n"));
                        } else {
                                tx--;
                                goto end;
                        }
                }

                result = acpi_thermal_cpufreq_decrease(pr->id);
                if (result) {
                        /*
                         * We only could get -ERANGE, 1 or 0.
                         * In the first two cases we reached max freq again.
                         */
                        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                          "At minimum performance state\n"));
                        max_tx_px = 1;
                } else
                        max_tx_px = 0;

                break;
        }

      end:
        if (pr->flags.throttling) {
                pr->limit.thermal.px = 0;
                pr->limit.thermal.tx = tx;

                result = acpi_processor_apply_limit(pr);
                if (result)
                        printk(KERN_ERR PREFIX "Unable to set thermal limit\n");

                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Thermal limit now (P%d:T%d)\n",
                                  pr->limit.thermal.px, pr->limit.thermal.tx));
        } else
                result = 0;
        if (max_tx_px)
                return 1;
        else
                return result;
}

int acpi_processor_get_limit_info(struct acpi_processor *pr)
{

        if (!pr)
                return -EINVAL;

        if (pr->flags.throttling)
                pr->flags.limit = 1;

        return 0;
}

/* thermal coolign device callbacks */
static int acpi_processor_max_state(struct acpi_processor *pr)
{
        int max_state = 0;

        /*
         * There exists four states according to
         * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
         */
        max_state += cpufreq_get_max_state(pr->id);
        if (pr->flags.throttling)
                max_state += (pr->throttling.state_count -1);

        return max_state;
}
static int
processor_get_max_state(struct thermal_cooling_device *cdev,
                        unsigned long *state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr = acpi_driver_data(device);

        if (!device || !pr)
                return -EINVAL;

        *state = acpi_processor_max_state(pr);
        return 0;
}

static int
processor_get_cur_state(struct thermal_cooling_device *cdev,
                        unsigned long *cur_state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr = acpi_driver_data(device);

        if (!device || !pr)
                return -EINVAL;

        *cur_state = cpufreq_get_cur_state(pr->id);
        if (pr->flags.throttling)
                *cur_state += pr->throttling.state;
        return 0;
}

static int
processor_set_cur_state(struct thermal_cooling_device *cdev,
                        unsigned long state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr = acpi_driver_data(device);
        int result = 0;
        int max_pstate;

        if (!device || !pr)
                return -EINVAL;

        max_pstate = cpufreq_get_max_state(pr->id);

        if (state > acpi_processor_max_state(pr))
                return -EINVAL;

        if (state <= max_pstate) {
                if (pr->flags.throttling && pr->throttling.state)
                        result = acpi_processor_set_throttling(pr, 0);
                cpufreq_set_cur_state(pr->id, state);
        } else {
                cpufreq_set_cur_state(pr->id, max_pstate);
                result = acpi_processor_set_throttling(pr,
                                state - max_pstate);
        }
        return result;
}

struct thermal_cooling_device_ops processor_cooling_ops = {
        .get_max_state = processor_get_max_state,
        .get_cur_state = processor_get_cur_state,
        .set_cur_state = processor_set_cur_state,
};

/* /proc interface */

static int acpi_processor_limit_seq_show(struct seq_file *seq, void *offset)
{
        struct acpi_processor *pr = (struct acpi_processor *)seq->private;


        if (!pr)
                goto end;

        if (!pr->flags.limit) {
                seq_puts(seq, "<not supported>\n");
                goto end;
        }

        seq_printf(seq, "active limit:            P%d:T%d\n"
                   "user limit:              P%d:T%d\n"
                   "thermal limit:           P%d:T%d\n",
                   pr->limit.state.px, pr->limit.state.tx,
                   pr->limit.user.px, pr->limit.user.tx,
                   pr->limit.thermal.px, pr->limit.thermal.tx);

      end:
        return 0;
}

static int acpi_processor_limit_open_fs(struct inode *inode, struct file *file)
{
        return single_open(file, acpi_processor_limit_seq_show,
                           PDE(inode)->data);
}

static ssize_t acpi_processor_write_limit(struct file * file,
                                          const char __user * buffer,
                                          size_t count, loff_t * data)
{
        int result = 0;
        struct seq_file *m = file->private_data;
        struct acpi_processor *pr = m->private;
        char limit_string[25] = { '\0' };
        int px = 0;
        int tx = 0;


        if (!pr || (count > sizeof(limit_string) - 1)) {
                return -EINVAL;
        }

        if (copy_from_user(limit_string, buffer, count)) {
                return -EFAULT;
        }

        limit_string[count] = '\0';

        if (sscanf(limit_string, "%d:%d", &px, &tx) != 2) {
                printk(KERN_ERR PREFIX "Invalid data format\n");
                return -EINVAL;
        }

        if (pr->flags.throttling) {
                if ((tx < 0) || (tx > (pr->throttling.state_count - 1))) {
                        printk(KERN_ERR PREFIX "Invalid tx\n");
                        return -EINVAL;
                }
                pr->limit.user.tx = tx;
        }

        result = acpi_processor_apply_limit(pr);

        return count;
}

const struct file_operations acpi_processor_limit_fops = {
        .owner = THIS_MODULE,
        .open = acpi_processor_limit_open_fs,
        .read = seq_read,
        .write = acpi_processor_write_limit,
        .llseek = seq_lseek,
        .release = single_release,
};