// SPDX-License-Identifier: GPL-2.0-only
/*
 * POWER platform energy management driver
 * Copyright (C) 2010 IBM Corporation
 *
 * 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>
#include <asm/prom.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;
        struct property *info;
        int thread_index;
        int rc = 1;
        u32 ret = 0;

        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;

        /* Convert logical cpu number to core number */
        thread_index = cpu_core_index_of_thread(cpu);

        info = of_find_property(dn, "ibm,drc-info", NULL);
        if (info) {
                struct of_drc_info drc;
                int j;
                u32 num_set_entries;
                const __be32 *value;

                value = of_prop_next_u32(info, NULL, &num_set_entries);
                if (!value)
                        goto err_of_node_put;
                else
                        value++;

                for (j = 0; j < num_set_entries; j++) {

                        of_read_drc_info_cell(&info, &value, &drc);
                        if (strncmp(drc.drc_type, "CPU", 3))
                                goto err;

                        if (thread_index < drc.last_drc_index)
                                break;
                }

                ret = drc.drc_index_start + (thread_index * drc.sequential_inc);
        } else {
                u32 nr_drc_indexes, thread_drc_index;

                /*
                 * The first element of ibm,drc-indexes array is the
                 * number of drc_indexes returned in the list.  Hence
                 * thread_index+1 will get the drc_index corresponding
                 * to core number thread_index.
                 */
                rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
                                                0, &nr_drc_indexes);
                if (rc)
                        goto err_of_node_put;

                WARN_ON_ONCE(thread_index > nr_drc_indexes);
                rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
                                                thread_index + 1,
                                                &thread_drc_index);
                if (rc)
                        goto err_of_node_put;

                ret = thread_drc_index;
        }

        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;
        struct property *info;
        const int *indexes;
        int thread_index = 0, cpu = 0;
        int rc = 1;

        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;
        info = of_find_property(dn, "ibm,drc-info", NULL);
        if (info) {
                struct of_drc_info drc;
                int j;
                u32 num_set_entries;
                const __be32 *value;

                value = of_prop_next_u32(info, NULL, &num_set_entries);
                if (!value)
                        goto err_of_node_put;
                else
                        value++;

                for (j = 0; j < num_set_entries; j++) {

                        of_read_drc_info_cell(&info, &value, &drc);
                        if (strncmp(drc.drc_type, "CPU", 3))
                                goto err;

                        if (drc_index > drc.last_drc_index) {
                                cpu += drc.num_sequential_elems;
                                continue;
                        }
                        cpu += ((drc_index - drc.drc_index_start) /
                                drc.sequential_inc);

                        thread_index = cpu_first_thread_of_core(cpu);
                        rc = 0;
                        break;
                }
        } else {
                unsigned long int i;

                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 */
                thread_index = 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 thread_index;
}

/*
 * 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
 */

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

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

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

static 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, *dev_root;

        if (!firmware_has_feature(FW_FEATURE_BEST_ENERGY))
                return 0; /* H_BEST_ENERGY hcall not supported */

        /* Create the sysfs files */
        dev_root = bus_get_dev_root(&cpu_subsys);
        if (dev_root) {
                err = device_create_file(dev_root, &attr_cpu_activate_hint_list);
                if (!err)
                        err = device_create_file(dev_root, &attr_cpu_deactivate_hint_list);
                put_device(dev_root);
                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, *dev_root;

        if (!sysfs_entries)
                return;

        /* Remove the sysfs files */
        dev_root = bus_get_dev_root(&cpu_subsys);
        if (dev_root) {
                device_remove_file(dev_root, &attr_cpu_activate_hint_list);
                device_remove_file(dev_root, &attr_cpu_deactivate_hint_list);
                put_device(dev_root);
        }

        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");