// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Platform energy and frequency attributes driver
 *
 * This driver creates a sys file at /sys/firmware/papr/ which encapsulates a
 * directory structure containing files in keyword - value pairs that specify
 * energy and frequency configuration of the system.
 *
 * The format of exposing the sysfs information is as follows:
 * /sys/firmware/papr/energy_scale_info/
 *  |-- <id>/
 *    |-- desc
 *    |-- value
 *    |-- value_desc (if exists)
 *  |-- <id>/
 *    |-- desc
 *    |-- value
 *    |-- value_desc (if exists)
 *
 * Copyright 2022 IBM Corp.
 */

#include <asm/hvcall.h>
#include <asm/machdep.h>
#include <asm/firmware.h>

#include "pseries.h"

/*
 * Flag attributes to fetch either all or one attribute from the HCALL
 * flag = BE(0) => fetch all attributes with firstAttributeId = 0
 * flag = BE(1) => fetch a single attribute with firstAttributeId = id
 */
#define ESI_FLAGS_ALL           0
#define ESI_FLAGS_SINGLE        (1ull << 63)

#define KOBJ_MAX_ATTRS          3

#define ESI_HDR_SIZE            sizeof(struct h_energy_scale_info_hdr)
#define ESI_ATTR_SIZE           sizeof(struct energy_scale_attribute)
#define CURR_MAX_ESI_ATTRS      8

struct energy_scale_attribute {
        __be64 id;
        __be64 val;
        u8 desc[64];
        u8 value_desc[64];
} __packed;

struct h_energy_scale_info_hdr {
        __be64 num_attrs;
        __be64 array_offset;
        u8 data_header_version;
} __packed;

struct papr_attr {
        u64 id;
        struct kobj_attribute kobj_attr;
};

struct papr_group {
        struct attribute_group pg;
        struct papr_attr pgattrs[KOBJ_MAX_ATTRS];
};

static struct papr_group *papr_groups;
/* /sys/firmware/papr */
static struct kobject *papr_kobj;
/* /sys/firmware/papr/energy_scale_info */
static struct kobject *esi_kobj;

/*
 * Energy modes can change dynamically hence making a new hcall each time the
 * information needs to be retrieved
 */
static int papr_get_attr(u64 id, struct energy_scale_attribute *esi)
{
        int esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * ESI_ATTR_SIZE);
        int ret, max_esi_attrs = CURR_MAX_ESI_ATTRS;
        struct energy_scale_attribute *curr_esi;
        struct h_energy_scale_info_hdr *hdr;
        char *buf;

        buf = kmalloc(esi_buf_size, GFP_KERNEL);
        if (buf == NULL)
                return -ENOMEM;

retry:
        ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
                                 id, virt_to_phys(buf),
                                 esi_buf_size);

        /*
         * If the hcall fails with not enough memory for either the
         * header or data, attempt to allocate more
         */
        if (ret == H_PARTIAL || ret == H_P4) {
                char *temp_buf;

                max_esi_attrs += 4;
                esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * max_esi_attrs);

                temp_buf = krealloc(buf, esi_buf_size, GFP_KERNEL);
                if (temp_buf) {
                        buf = temp_buf;
                } else {
                        ret = -ENOMEM;
                        goto out_buf;
                }

                goto retry;
        }

        if (ret != H_SUCCESS) {
                pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
                ret = -EIO;
                goto out_buf;
        }

        hdr = (struct h_energy_scale_info_hdr *) buf;
        curr_esi = (struct energy_scale_attribute *)
                (buf + be64_to_cpu(hdr->array_offset));

        if (esi_buf_size <
            be64_to_cpu(hdr->array_offset) + (be64_to_cpu(hdr->num_attrs)
            * sizeof(struct energy_scale_attribute))) {
                ret = -EIO;
                goto out_buf;
        }

        *esi = *curr_esi;

out_buf:
        kfree(buf);

        return ret;
}

/*
 * Extract and export the description of the energy scale attributes
 */
static ssize_t desc_show(struct kobject *kobj,
                          struct kobj_attribute *kobj_attr,
                          char *buf)
{
        struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
                                               kobj_attr);
        struct energy_scale_attribute esi;
        int ret;

        ret = papr_get_attr(pattr->id, &esi);
        if (ret)
                return ret;

        return sysfs_emit(buf, "%s\n", esi.desc);
}

/*
 * Extract and export the numeric value of the energy scale attributes
 */
static ssize_t val_show(struct kobject *kobj,
                         struct kobj_attribute *kobj_attr,
                         char *buf)
{
        struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
                                               kobj_attr);
        struct energy_scale_attribute esi;
        int ret;

        ret = papr_get_attr(pattr->id, &esi);
        if (ret)
                return ret;

        return sysfs_emit(buf, "%llu\n", be64_to_cpu(esi.val));
}

/*
 * Extract and export the value description in string format of the energy
 * scale attributes
 */
static ssize_t val_desc_show(struct kobject *kobj,
                              struct kobj_attribute *kobj_attr,
                              char *buf)
{
        struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
                                               kobj_attr);
        struct energy_scale_attribute esi;
        int ret;

        ret = papr_get_attr(pattr->id, &esi);
        if (ret)
                return ret;

        return sysfs_emit(buf, "%s\n", esi.value_desc);
}

static struct papr_ops_info {
        const char *attr_name;
        ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *kobj_attr,
                        char *buf);
} ops_info[KOBJ_MAX_ATTRS] = {
        { "desc", desc_show },
        { "value", val_show },
        { "value_desc", val_desc_show },
};

static void add_attr(u64 id, int index, struct papr_attr *attr)
{
        attr->id = id;
        sysfs_attr_init(&attr->kobj_attr.attr);
        attr->kobj_attr.attr.name = ops_info[index].attr_name;
        attr->kobj_attr.attr.mode = 0444;
        attr->kobj_attr.show = ops_info[index].show;
}

static int add_attr_group(u64 id, struct papr_group *pg, bool show_val_desc)
{
        int i;

        for (i = 0; i < KOBJ_MAX_ATTRS; i++) {
                if (!strcmp(ops_info[i].attr_name, "value_desc") &&
                    !show_val_desc) {
                        continue;
                }
                add_attr(id, i, &pg->pgattrs[i]);
                pg->pg.attrs[i] = &pg->pgattrs[i].kobj_attr.attr;
        }

        return sysfs_create_group(esi_kobj, &pg->pg);
}


static int __init papr_init(void)
{
        int esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * ESI_ATTR_SIZE);
        int ret, idx, i, max_esi_attrs = CURR_MAX_ESI_ATTRS;
        struct h_energy_scale_info_hdr *esi_hdr;
        struct energy_scale_attribute *esi_attrs;
        uint64_t num_attrs;
        char *esi_buf;

        if (!firmware_has_feature(FW_FEATURE_LPAR) ||
            !firmware_has_feature(FW_FEATURE_ENERGY_SCALE_INFO)) {
                return -ENXIO;
        }

        esi_buf = kmalloc(esi_buf_size, GFP_KERNEL);
        if (esi_buf == NULL)
                return -ENOMEM;
        /*
         * hcall(
         * uint64 H_GET_ENERGY_SCALE_INFO,  // Get energy scale info
         * uint64 flags,            // Per the flag request
         * uint64 firstAttributeId, // The attribute id
         * uint64 bufferAddress,    // Guest physical address of the output buffer
         * uint64 bufferSize);      // The size in bytes of the output buffer
         */
retry:

        ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_ALL, 0,
                                 virt_to_phys(esi_buf), esi_buf_size);

        /*
         * If the hcall fails with not enough memory for either the
         * header or data, attempt to allocate more
         */
        if (ret == H_PARTIAL || ret == H_P4) {
                char *temp_esi_buf;

                max_esi_attrs += 4;
                esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * max_esi_attrs);

                temp_esi_buf = krealloc(esi_buf, esi_buf_size, GFP_KERNEL);
                if (temp_esi_buf)
                        esi_buf = temp_esi_buf;
                else
                        return -ENOMEM;

                goto retry;
        }

        if (ret != H_SUCCESS) {
                pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO, ret: %d\n", ret);
                goto out_free_esi_buf;
        }

        esi_hdr = (struct h_energy_scale_info_hdr *) esi_buf;
        num_attrs = be64_to_cpu(esi_hdr->num_attrs);
        esi_attrs = (struct energy_scale_attribute *)
                    (esi_buf + be64_to_cpu(esi_hdr->array_offset));

        if (esi_buf_size <
            be64_to_cpu(esi_hdr->array_offset) +
            (num_attrs * sizeof(struct energy_scale_attribute))) {
                goto out_free_esi_buf;
        }

        papr_groups = kzalloc_objs(*papr_groups, num_attrs);
        if (!papr_groups)
                goto out_free_esi_buf;

        papr_kobj = kobject_create_and_add("papr", firmware_kobj);
        if (!papr_kobj) {
                pr_warn("kobject_create_and_add papr failed\n");
                goto out_papr_groups;
        }

        esi_kobj = kobject_create_and_add("energy_scale_info", papr_kobj);
        if (!esi_kobj) {
                pr_warn("kobject_create_and_add energy_scale_info failed\n");
                goto out_kobj;
        }

        /* Allocate the groups before registering */
        for (idx = 0; idx < num_attrs; idx++) {
                papr_groups[idx].pg.attrs = kzalloc_objs(*papr_groups[idx].pg.attrs,
                                                         KOBJ_MAX_ATTRS + 1);
                if (!papr_groups[idx].pg.attrs)
                        goto out_pgattrs;

                papr_groups[idx].pg.name = kasprintf(GFP_KERNEL, "%lld",
                                             be64_to_cpu(esi_attrs[idx].id));
                if (papr_groups[idx].pg.name == NULL)
                        goto out_pgattrs;
        }

        for (idx = 0; idx < num_attrs; idx++) {
                bool show_val_desc = true;

                /* Do not add the value desc attr if it does not exist */
                if (strnlen(esi_attrs[idx].value_desc,
                            sizeof(esi_attrs[idx].value_desc)) == 0)
                        show_val_desc = false;

                if (add_attr_group(be64_to_cpu(esi_attrs[idx].id),
                                   &papr_groups[idx],
                                   show_val_desc)) {
                        pr_warn("Failed to create papr attribute group %s\n",
                                papr_groups[idx].pg.name);
                        idx = num_attrs;
                        goto out_pgattrs;
                }
        }

        kfree(esi_buf);
        return 0;
out_pgattrs:
        for (i = 0; i < idx ; i++) {
                kfree(papr_groups[i].pg.attrs);
                kfree(papr_groups[i].pg.name);
        }
        kobject_put(esi_kobj);
out_kobj:
        kobject_put(papr_kobj);
out_papr_groups:
        kfree(papr_groups);
out_free_esi_buf:
        kfree(esi_buf);

        return -ENOMEM;
}

machine_device_initcall(pseries, papr_init);