// SPDX-License-Identifier: GPL-2.0-only
/*
 * Power capping class
 * Copyright (c) 2013, Intel Corporation.
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/kstrtox.h>
#include <linux/slab.h>
#include <linux/powercap.h>

#define to_powercap_zone(n) container_of(n, struct powercap_zone, dev)
#define to_powercap_control_type(n) \
                        container_of(n, struct powercap_control_type, dev)

/* Power zone show function */
#define define_power_zone_show(_attr)           \
static ssize_t _attr##_show(struct device *dev, \
                                        struct device_attribute *dev_attr,\
                                        char *buf) \
{ \
        u64 value; \
        ssize_t len = -EINVAL; \
        struct powercap_zone *power_zone = to_powercap_zone(dev); \
        \
        if (power_zone->ops->get_##_attr) { \
                if (!power_zone->ops->get_##_attr(power_zone, &value)) \
                        len = sysfs_emit(buf, "%lld\n", value); \
        } \
        \
        return len; \
}

/* The only meaningful input is 0 (reset), others are silently ignored */
#define define_power_zone_store(_attr)          \
static ssize_t _attr##_store(struct device *dev,\
                                struct device_attribute *dev_attr, \
                                const char *buf, size_t count) \
{ \
        int err; \
        struct powercap_zone *power_zone = to_powercap_zone(dev); \
        u64 value; \
        \
        err = kstrtoull(buf, 10, &value); \
        if (err) \
                return -EINVAL; \
        if (value) \
                return count; \
        if (power_zone->ops->reset_##_attr) { \
                if (!power_zone->ops->reset_##_attr(power_zone)) \
                        return count; \
        } \
        \
        return -EINVAL; \
}

/* Power zone constraint show function */
#define define_power_zone_constraint_show(_attr) \
static ssize_t show_constraint_##_attr(struct device *dev, \
                                struct device_attribute *dev_attr,\
                                char *buf) \
{ \
        u64 value; \
        ssize_t len = -ENODATA; \
        struct powercap_zone *power_zone = to_powercap_zone(dev); \
        int id; \
        struct powercap_zone_constraint *pconst;\
        \
        if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \
                return -EINVAL; \
        if (id >= power_zone->const_id_cnt)     \
                return -EINVAL; \
        pconst = &power_zone->constraints[id]; \
        if (pconst && pconst->ops && pconst->ops->get_##_attr) { \
                if (!pconst->ops->get_##_attr(power_zone, id, &value)) \
                        len = sysfs_emit(buf, "%lld\n", value); \
        } \
        \
        return len; \
}

/* Power zone constraint store function */
#define define_power_zone_constraint_store(_attr) \
static ssize_t store_constraint_##_attr(struct device *dev,\
                                struct device_attribute *dev_attr, \
                                const char *buf, size_t count) \
{ \
        int err; \
        u64 value; \
        struct powercap_zone *power_zone = to_powercap_zone(dev); \
        int id; \
        struct powercap_zone_constraint *pconst;\
        \
        if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \
                return -EINVAL; \
        if (id >= power_zone->const_id_cnt)     \
                return -EINVAL; \
        pconst = &power_zone->constraints[id]; \
        err = kstrtoull(buf, 10, &value); \
        if (err) \
                return -EINVAL; \
        if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
                if (!pconst->ops->set_##_attr(power_zone, id, value)) \
                        return count; \
        } \
        \
        return -ENODATA; \
}

/* Power zone information callbacks */
define_power_zone_show(power_uw);
define_power_zone_show(max_power_range_uw);
define_power_zone_show(energy_uj);
define_power_zone_store(energy_uj);
define_power_zone_show(max_energy_range_uj);

/* Power zone attributes */
static DEVICE_ATTR_RO(max_power_range_uw);
static DEVICE_ATTR_RO(power_uw);
static DEVICE_ATTR_RO(max_energy_range_uj);
static DEVICE_ATTR_RW(energy_uj);

/* Power zone constraint attributes callbacks */
define_power_zone_constraint_show(power_limit_uw);
define_power_zone_constraint_store(power_limit_uw);
define_power_zone_constraint_show(time_window_us);
define_power_zone_constraint_store(time_window_us);
define_power_zone_constraint_show(max_power_uw);
define_power_zone_constraint_show(min_power_uw);
define_power_zone_constraint_show(max_time_window_us);
define_power_zone_constraint_show(min_time_window_us);

/* For one time seeding of constraint device attributes */
struct powercap_constraint_attr {
        struct device_attribute power_limit_attr;
        struct device_attribute time_window_attr;
        struct device_attribute max_power_attr;
        struct device_attribute min_power_attr;
        struct device_attribute max_time_window_attr;
        struct device_attribute min_time_window_attr;
        struct device_attribute name_attr;
};

static struct powercap_constraint_attr
                                constraint_attrs[MAX_CONSTRAINTS_PER_ZONE];

/* A list of powercap control_types */
static LIST_HEAD(powercap_cntrl_list);
/* Mutex to protect list of powercap control_types */
static DEFINE_MUTEX(powercap_cntrl_list_lock);

#define POWERCAP_CONSTRAINT_NAME_LEN    30 /* Some limit to avoid overflow */
static ssize_t show_constraint_name(struct device *dev,
                                struct device_attribute *dev_attr,
                                char *buf)
{
        const char *name;
        struct powercap_zone *power_zone = to_powercap_zone(dev);
        int id;
        ssize_t len = -ENODATA;
        struct powercap_zone_constraint *pconst;

        if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1)
                return -EINVAL;
        if (id >= power_zone->const_id_cnt)
                return -EINVAL;
        pconst = &power_zone->constraints[id];

        if (pconst && pconst->ops && pconst->ops->get_name) {
                name = pconst->ops->get_name(power_zone, id);
                if (name) {
                        len = sysfs_emit(buf, "%.*s\n",
                                         POWERCAP_CONSTRAINT_NAME_LEN - 1, name);
                }
        }

        return len;
}

static int create_constraint_attribute(int id, const char *name,
                                int mode,
                                struct device_attribute *dev_attr,
                                ssize_t (*show)(struct device *,
                                        struct device_attribute *, char *),
                                ssize_t (*store)(struct device *,
                                        struct device_attribute *,
                                const char *, size_t)
                                )
{

        dev_attr->attr.name = kasprintf(GFP_KERNEL, "constraint_%d_%s",
                                                                id, name);
        if (!dev_attr->attr.name)
                return -ENOMEM;
        dev_attr->attr.mode = mode;
        dev_attr->show = show;
        dev_attr->store = store;

        return 0;
}

static void free_constraint_attributes(void)
{
        int i;

        for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
                kfree(constraint_attrs[i].power_limit_attr.attr.name);
                kfree(constraint_attrs[i].time_window_attr.attr.name);
                kfree(constraint_attrs[i].name_attr.attr.name);
                kfree(constraint_attrs[i].max_power_attr.attr.name);
                kfree(constraint_attrs[i].min_power_attr.attr.name);
                kfree(constraint_attrs[i].max_time_window_attr.attr.name);
                kfree(constraint_attrs[i].min_time_window_attr.attr.name);
        }
}

static int seed_constraint_attributes(void)
{
        int i;
        int ret;

        for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
                ret = create_constraint_attribute(i, "power_limit_uw",
                                        S_IWUSR | S_IRUGO,
                                        &constraint_attrs[i].power_limit_attr,
                                        show_constraint_power_limit_uw,
                                        store_constraint_power_limit_uw);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "time_window_us",
                                        S_IWUSR | S_IRUGO,
                                        &constraint_attrs[i].time_window_attr,
                                        show_constraint_time_window_us,
                                        store_constraint_time_window_us);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "name", S_IRUGO,
                                &constraint_attrs[i].name_attr,
                                show_constraint_name,
                                NULL);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "max_power_uw", S_IRUGO,
                                &constraint_attrs[i].max_power_attr,
                                show_constraint_max_power_uw,
                                NULL);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "min_power_uw", S_IRUGO,
                                &constraint_attrs[i].min_power_attr,
                                show_constraint_min_power_uw,
                                NULL);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "max_time_window_us",
                                S_IRUGO,
                                &constraint_attrs[i].max_time_window_attr,
                                show_constraint_max_time_window_us,
                                NULL);
                if (ret)
                        goto err_alloc;
                ret = create_constraint_attribute(i, "min_time_window_us",
                                S_IRUGO,
                                &constraint_attrs[i].min_time_window_attr,
                                show_constraint_min_time_window_us,
                                NULL);
                if (ret)
                        goto err_alloc;

        }

        return 0;

err_alloc:
        free_constraint_attributes();

        return ret;
}

static int create_constraints(struct powercap_zone *power_zone,
                        int nr_constraints,
                        const struct powercap_zone_constraint_ops *const_ops)
{
        int i;
        int ret = 0;
        int count;
        struct powercap_zone_constraint *pconst;

        if (!power_zone || !const_ops || !const_ops->get_power_limit_uw ||
                                        !const_ops->set_power_limit_uw ||
                                        !const_ops->get_time_window_us ||
                                        !const_ops->set_time_window_us)
                return -EINVAL;

        count = power_zone->zone_attr_count;
        for (i = 0; i < nr_constraints; ++i) {
                pconst = &power_zone->constraints[i];
                pconst->ops = const_ops;
                pconst->id = power_zone->const_id_cnt;
                power_zone->const_id_cnt++;
                power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].power_limit_attr.attr;
                power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].time_window_attr.attr;
                if (pconst->ops->get_name)
                        power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].name_attr.attr;
                if (pconst->ops->get_max_power_uw)
                        power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].max_power_attr.attr;
                if (pconst->ops->get_min_power_uw)
                        power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].min_power_attr.attr;
                if (pconst->ops->get_max_time_window_us)
                        power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].max_time_window_attr.attr;
                if (pconst->ops->get_min_time_window_us)
                        power_zone->zone_dev_attrs[count++] =
                                &constraint_attrs[i].min_time_window_attr.attr;
        }
        power_zone->zone_attr_count = count;

        return ret;
}

static bool control_type_valid(void *control_type)
{
        struct powercap_control_type *pos = NULL;
        bool found = false;

        mutex_lock(&powercap_cntrl_list_lock);

        list_for_each_entry(pos, &powercap_cntrl_list, node) {
                if (pos == control_type) {
                        found = true;
                        break;
                }
        }
        mutex_unlock(&powercap_cntrl_list_lock);

        return found;
}

static ssize_t name_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf)
{
        struct powercap_zone *power_zone = to_powercap_zone(dev);

        return sysfs_emit(buf, "%s\n", power_zone->name);
}

static DEVICE_ATTR_RO(name);

/* Create zone and attributes in sysfs */
static void create_power_zone_common_attributes(
                                        struct powercap_zone *power_zone)
{
        int count = 0;

        power_zone->zone_dev_attrs[count++] = &dev_attr_name.attr;
        if (power_zone->ops->get_max_energy_range_uj)
                power_zone->zone_dev_attrs[count++] =
                                        &dev_attr_max_energy_range_uj.attr;
        if (power_zone->ops->get_energy_uj) {
                if (power_zone->ops->reset_energy_uj)
                        dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUSR;
                else
                        dev_attr_energy_uj.attr.mode = S_IRUSR;
                power_zone->zone_dev_attrs[count++] =
                                        &dev_attr_energy_uj.attr;
        }
        if (power_zone->ops->get_power_uw)
                power_zone->zone_dev_attrs[count++] =
                                        &dev_attr_power_uw.attr;
        if (power_zone->ops->get_max_power_range_uw)
                power_zone->zone_dev_attrs[count++] =
                                        &dev_attr_max_power_range_uw.attr;
        power_zone->zone_dev_attrs[count] = NULL;
        power_zone->zone_attr_count = count;
}

static void powercap_release(struct device *dev)
{
        bool allocated;

        if (dev->parent) {
                struct powercap_zone *power_zone = to_powercap_zone(dev);

                /* Store flag as the release() may free memory */
                allocated = power_zone->allocated;
                /* Remove id from parent idr struct */
                idr_remove(power_zone->parent_idr, power_zone->id);
                /* Destroy idrs allocated for this zone */
                idr_destroy(&power_zone->idr);
                kfree(power_zone->name);
                kfree(power_zone->zone_dev_attrs);
                kfree(power_zone->constraints);
                if (power_zone->ops->release)
                        power_zone->ops->release(power_zone);
                if (allocated)
                        kfree(power_zone);
        } else {
                struct powercap_control_type *control_type =
                                                to_powercap_control_type(dev);

                /* Store flag as the release() may free memory */
                allocated = control_type->allocated;
                idr_destroy(&control_type->idr);
                mutex_destroy(&control_type->lock);
                if (control_type->ops && control_type->ops->release)
                        control_type->ops->release(control_type);
                if (allocated)
                        kfree(control_type);
        }
}

static ssize_t enabled_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf)
{
        bool mode = true;

        /* Default is enabled */
        if (dev->parent) {
                struct powercap_zone *power_zone = to_powercap_zone(dev);
                if (power_zone->ops->get_enable)
                        if (power_zone->ops->get_enable(power_zone, &mode))
                                mode = false;
        } else {
                struct powercap_control_type *control_type =
                                                to_powercap_control_type(dev);
                if (control_type->ops && control_type->ops->get_enable)
                        if (control_type->ops->get_enable(control_type, &mode))
                                mode = false;
        }

        return sysfs_emit(buf, "%d\n", mode);
}

static ssize_t enabled_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf,  size_t len)
{
        bool mode;

        if (kstrtobool(buf, &mode))
                return -EINVAL;
        if (dev->parent) {
                struct powercap_zone *power_zone = to_powercap_zone(dev);
                if (power_zone->ops->set_enable)
                        if (!power_zone->ops->set_enable(power_zone, mode))
                                return len;
        } else {
                struct powercap_control_type *control_type =
                                                to_powercap_control_type(dev);
                if (control_type->ops && control_type->ops->set_enable)
                        if (!control_type->ops->set_enable(control_type, mode))
                                return len;
        }

        return -ENOSYS;
}

static DEVICE_ATTR_RW(enabled);

static struct attribute *powercap_attrs[] = {
        &dev_attr_enabled.attr,
        NULL,
};
ATTRIBUTE_GROUPS(powercap);

static struct class powercap_class = {
        .name = "powercap",
        .dev_release = powercap_release,
        .dev_groups = powercap_groups,
};

struct powercap_zone *powercap_register_zone(
                        struct powercap_zone *power_zone,
                        struct powercap_control_type *control_type,
                        const char *name,
                        struct powercap_zone *parent,
                        const struct powercap_zone_ops *ops,
                        int nr_constraints,
                        const struct powercap_zone_constraint_ops *const_ops)
{
        int result;
        int nr_attrs;

        if (!name || !control_type || !ops ||
                        nr_constraints > MAX_CONSTRAINTS_PER_ZONE ||
                        (!ops->get_energy_uj && !ops->get_power_uw) ||
                        !control_type_valid(control_type))
                return ERR_PTR(-EINVAL);

        if (power_zone) {
                if (!ops->release)
                        return ERR_PTR(-EINVAL);
                memset(power_zone, 0, sizeof(*power_zone));
        } else {
                power_zone = kzalloc_obj(*power_zone);
                if (!power_zone)
                        return ERR_PTR(-ENOMEM);
                power_zone->allocated = true;
        }
        power_zone->ops = ops;
        power_zone->control_type_inst = control_type;
        if (!parent) {
                power_zone->dev.parent = &control_type->dev;
                power_zone->parent_idr = &control_type->idr;
        } else {
                power_zone->dev.parent = &parent->dev;
                power_zone->parent_idr = &parent->idr;
        }
        power_zone->dev.class = &powercap_class;

        mutex_lock(&control_type->lock);
        /* Using idr to get the unique id */
        result = idr_alloc(power_zone->parent_idr, NULL, 0, 0, GFP_KERNEL);
        if (result < 0)
                goto err_idr_alloc;

        power_zone->id = result;
        idr_init(&power_zone->idr);
        result = -ENOMEM;
        power_zone->name = kstrdup(name, GFP_KERNEL);
        if (!power_zone->name)
                goto err_name_alloc;
        power_zone->constraints = kzalloc_objs(*power_zone->constraints,
                                               nr_constraints);
        if (!power_zone->constraints)
                goto err_const_alloc;

        nr_attrs = nr_constraints * POWERCAP_CONSTRAINTS_ATTRS +
                                                POWERCAP_ZONE_MAX_ATTRS + 1;
        power_zone->zone_dev_attrs = kcalloc(nr_attrs, sizeof(void *),
                                             GFP_KERNEL);
        if (!power_zone->zone_dev_attrs)
                goto err_attr_alloc;
        create_power_zone_common_attributes(power_zone);
        result = create_constraints(power_zone, nr_constraints, const_ops);
        if (result)
                goto err_dev_ret;

        power_zone->zone_dev_attrs[power_zone->zone_attr_count] = NULL;
        power_zone->dev_zone_attr_group.attrs = power_zone->zone_dev_attrs;
        power_zone->dev_attr_groups[0] = &power_zone->dev_zone_attr_group;
        power_zone->dev_attr_groups[1] = NULL;
        power_zone->dev.groups = power_zone->dev_attr_groups;
        dev_set_name(&power_zone->dev, "%s:%x",
                                        dev_name(power_zone->dev.parent),
                                        power_zone->id);
        result = device_register(&power_zone->dev);
        if (result) {
                put_device(&power_zone->dev);
                mutex_unlock(&control_type->lock);

                return ERR_PTR(result);
        }

        control_type->nr_zones++;
        mutex_unlock(&control_type->lock);

        return power_zone;

err_dev_ret:
        kfree(power_zone->zone_dev_attrs);
err_attr_alloc:
        kfree(power_zone->constraints);
err_const_alloc:
        kfree(power_zone->name);
err_name_alloc:
        idr_remove(power_zone->parent_idr, power_zone->id);
err_idr_alloc:
        if (power_zone->allocated)
                kfree(power_zone);
        mutex_unlock(&control_type->lock);

        return ERR_PTR(result);
}
EXPORT_SYMBOL_GPL(powercap_register_zone);

int powercap_unregister_zone(struct powercap_control_type *control_type,
                                struct powercap_zone *power_zone)
{
        if (!power_zone || !control_type)
                return -EINVAL;

        mutex_lock(&control_type->lock);
        control_type->nr_zones--;
        mutex_unlock(&control_type->lock);

        device_unregister(&power_zone->dev);

        return 0;
}
EXPORT_SYMBOL_GPL(powercap_unregister_zone);

struct powercap_control_type *powercap_register_control_type(
                                struct powercap_control_type *control_type,
                                const char *name,
                                const struct powercap_control_type_ops *ops)
{
        int result;

        if (!name)
                return ERR_PTR(-EINVAL);
        if (control_type) {
                if (!ops || !ops->release)
                        return ERR_PTR(-EINVAL);
                memset(control_type, 0, sizeof(*control_type));
        } else {
                control_type = kzalloc_obj(*control_type);
                if (!control_type)
                        return ERR_PTR(-ENOMEM);
                control_type->allocated = true;
        }
        mutex_init(&control_type->lock);
        control_type->ops = ops;
        INIT_LIST_HEAD(&control_type->node);
        control_type->dev.class = &powercap_class;
        dev_set_name(&control_type->dev, "%s", name);
        idr_init(&control_type->idr);

        mutex_lock(&powercap_cntrl_list_lock);
        list_add_tail(&control_type->node, &powercap_cntrl_list);
        mutex_unlock(&powercap_cntrl_list_lock);

        result = device_register(&control_type->dev);
        if (result) {
                mutex_lock(&powercap_cntrl_list_lock);
                list_del(&control_type->node);
                mutex_unlock(&powercap_cntrl_list_lock);

                idr_destroy(&control_type->idr);
                put_device(&control_type->dev);
                return ERR_PTR(result);
        }

        return control_type;
}
EXPORT_SYMBOL_GPL(powercap_register_control_type);

int powercap_unregister_control_type(struct powercap_control_type *control_type)
{
        struct powercap_control_type *pos = NULL;

        if (control_type->nr_zones) {
                dev_err(&control_type->dev, "Zones of this type still not freed\n");
                return -EINVAL;
        }
        mutex_lock(&powercap_cntrl_list_lock);
        list_for_each_entry(pos, &powercap_cntrl_list, node) {
                if (pos == control_type) {
                        list_del(&control_type->node);
                        mutex_unlock(&powercap_cntrl_list_lock);
                        device_unregister(&control_type->dev);
                        return 0;
                }
        }
        mutex_unlock(&powercap_cntrl_list_lock);

        return -ENODEV;
}
EXPORT_SYMBOL_GPL(powercap_unregister_control_type);

static int __init powercap_init(void)
{
        int result;

        result = seed_constraint_attributes();
        if (result)
                return result;

        return class_register(&powercap_class);
}

fs_initcall(powercap_init);

MODULE_DESCRIPTION("PowerCap sysfs Driver");
MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");