/*
 * POWER platform energy management driver
 * Copyright (C) 2010 IBM Corporation
 *
 * 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.
 *
 * This pseries platform device driver provides access to
 * platform energy management capabilities.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/of.h>
#include <asm/cputhreads.h>
#include <asm/page.h>
#include <asm/hvcall.h>
#include <asm/firmware.h>


#define MODULE_VERS "1.0"
#define MODULE_NAME "pseries_energy"

/* Driver flags */

static int sysfs_entries;

/* Helper routines */

/* Helper Routines to convert between drc_index to cpu numbers */

static u32 cpu_to_drc_index(int cpu)
{
        struct device_node *dn = NULL;
        const int *indexes;
        int i;
        int rc = 1;
        u32 ret = 0;

        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;
        indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
        if (indexes == NULL)
                goto err_of_node_put;
        /* Convert logical cpu number to core number */
        i = cpu_core_index_of_thread(cpu);
        /*
         * The first element indexes[0] is the number of drc_indexes
         * returned in the list.  Hence i+1 will get the drc_index
         * corresponding to core number i.
         */
        WARN_ON(i > indexes[0]);
        ret = indexes[i + 1];
        rc = 0;

err_of_node_put:
        of_node_put(dn);
err:
        if (rc)
                printk(KERN_WARNING "cpu_to_drc_index(%d) failed", cpu);
        return ret;
}

static int drc_index_to_cpu(u32 drc_index)
{
        struct device_node *dn = NULL;
        const int *indexes;
        int i, cpu = 0;
        int rc = 1;

        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;
        indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
        if (indexes == NULL)
                goto err_of_node_put;
        /*
         * First element in the array is the number of drc_indexes
         * returned.  Search through the list to find the matching
         * drc_index and get the core number
         */
        for (i = 0; i < indexes[0]; i++) {
                if (indexes[i + 1] == drc_index)
                        break;
        }
        /* Convert core number to logical cpu number */
        cpu = cpu_first_thread_of_core(i);
        rc = 0;

err_of_node_put:
        of_node_put(dn);
err:
        if (rc)
                printk(KERN_WARNING "drc_index_to_cpu(%d) failed", drc_index);
        return cpu;
}

/*
 * pseries hypervisor call H_BEST_ENERGY provides hints to OS on
 * preferred logical cpus to activate or deactivate for optimized
 * energy consumption.
 */

#define FLAGS_MODE1     0x004E200000080E01UL
#define FLAGS_MODE2     0x004E200000080401UL
#define FLAGS_ACTIVATE  0x100

static ssize_t get_best_energy_list(char *page, int activate)
{
        int rc, cnt, i, cpu;
        unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
        unsigned long flags = 0;
        u32 *buf_page;
        char *s = page;

        buf_page = (u32 *) get_zeroed_page(GFP_KERNEL);
        if (!buf_page)
                return -ENOMEM;

        flags = FLAGS_MODE1;
        if (activate)
                flags |= FLAGS_ACTIVATE;

        rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags, 0, __pa(buf_page),
                                0, 0, 0, 0, 0, 0);
        if (rc != H_SUCCESS) {
                free_page((unsigned long) buf_page);
                return -EINVAL;
        }

        cnt = retbuf[0];
        for (i = 0; i < cnt; i++) {
                cpu = drc_index_to_cpu(buf_page[2*i+1]);
                if ((cpu_online(cpu) && !activate) ||
                    (!cpu_online(cpu) && activate))
                        s += sprintf(s, "%d,", cpu);
        }
        if (s > page) { /* Something to show */
                s--; /* Suppress last comma */
                s += sprintf(s, "\n");
        }

        free_page((unsigned long) buf_page);
        return s-page;
}

static ssize_t get_best_energy_data(struct device *dev,
                                        char *page, int activate)
{
        int rc;
        unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
        unsigned long flags = 0;

        flags = FLAGS_MODE2;
        if (activate)
                flags |= FLAGS_ACTIVATE;

        rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags,
                                cpu_to_drc_index(dev->id),
                                0, 0, 0, 0, 0, 0, 0);

        if (rc != H_SUCCESS)
                return -EINVAL;

        return sprintf(page, "%lu\n", retbuf[1] >> 32);
}

/* Wrapper functions */

static ssize_t cpu_activate_hint_list_show(struct device *dev,
                        struct device_attribute *attr, char *page)
{
        return get_best_energy_list(page, 1);
}

static ssize_t cpu_deactivate_hint_list_show(struct device *dev,
                        struct device_attribute *attr, char *page)
{
        return get_best_energy_list(page, 0);
}

static ssize_t percpu_activate_hint_show(struct device *dev,
                        struct device_attribute *attr, char *page)
{
        return get_best_energy_data(dev, page, 1);
}

static ssize_t percpu_deactivate_hint_show(struct device *dev,
                        struct device_attribute *attr, char *page)
{
        return get_best_energy_data(dev, page, 0);
}

/*
 * Create sysfs interface:
 * /sys/devices/system/cpu/pseries_activate_hint_list
 * /sys/devices/system/cpu/pseries_deactivate_hint_list
 *      Comma separated list of cpus to activate or deactivate
 * /sys/devices/system/cpu/cpuN/pseries_activate_hint
 * /sys/devices/system/cpu/cpuN/pseries_deactivate_hint
 *      Per-cpu value of the hint
 */

struct device_attribute attr_cpu_activate_hint_list =
                __ATTR(pseries_activate_hint_list, 0444,
                cpu_activate_hint_list_show, NULL);

struct device_attribute attr_cpu_deactivate_hint_list =
                __ATTR(pseries_deactivate_hint_list, 0444,
                cpu_deactivate_hint_list_show, NULL);

struct device_attribute attr_percpu_activate_hint =
                __ATTR(pseries_activate_hint, 0444,
                percpu_activate_hint_show, NULL);

struct device_attribute attr_percpu_deactivate_hint =
                __ATTR(pseries_deactivate_hint, 0444,
                percpu_deactivate_hint_show, NULL);

static int __init pseries_energy_init(void)
{
        int cpu, err;
        struct device *cpu_dev;

        if (!firmware_has_feature(FW_FEATURE_BEST_ENERGY)) {
                printk(KERN_INFO "Hypercall H_BEST_ENERGY not supported\n");
                return 0;
        }
        /* Create the sysfs files */
        err = device_create_file(cpu_subsys.dev_root,
                                &attr_cpu_activate_hint_list);
        if (!err)
                err = device_create_file(cpu_subsys.dev_root,
                                &attr_cpu_deactivate_hint_list);

        if (err)
                return err;
        for_each_possible_cpu(cpu) {
                cpu_dev = get_cpu_device(cpu);
                err = device_create_file(cpu_dev,
                                &attr_percpu_activate_hint);
                if (err)
                        break;
                err = device_create_file(cpu_dev,
                                &attr_percpu_deactivate_hint);
                if (err)
                        break;
        }

        if (err)
                return err;

        sysfs_entries = 1; /* Removed entries on cleanup */
        return 0;

}

static void __exit pseries_energy_cleanup(void)
{
        int cpu;
        struct device *cpu_dev;

        if (!sysfs_entries)
                return;

        /* Remove the sysfs files */
        device_remove_file(cpu_subsys.dev_root, &attr_cpu_activate_hint_list);
        device_remove_file(cpu_subsys.dev_root, &attr_cpu_deactivate_hint_list);

        for_each_possible_cpu(cpu) {
                cpu_dev = get_cpu_device(cpu);
                sysfs_remove_file(&cpu_dev->kobj,
                                &attr_percpu_activate_hint.attr);
                sysfs_remove_file(&cpu_dev->kobj,
                                &attr_percpu_deactivate_hint.attr);
        }
}

module_init(pseries_energy_init);
module_exit(pseries_energy_cleanup);
MODULE_DESCRIPTION("Driver for pSeries platform energy management");
MODULE_AUTHOR("Vaidyanathan Srinivasan");
MODULE_LICENSE("GPL");