// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) ST-Ericsson SA 2011
 *
 * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.
 */

#include <linux/sysfs.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/spinlock.h>
#include <linux/sys_soc.h>
#include <linux/err.h>
#include <linux/glob.h>

static DEFINE_IDA(soc_ida);

/* Prototype to allow declarations of DEVICE_ATTR(<foo>) before soc_info_show */
static ssize_t soc_info_show(struct device *dev, struct device_attribute *attr,
                             char *buf);

struct soc_device {
        struct device dev;
        struct soc_device_attribute *attr;
        int soc_dev_num;
};

static const struct bus_type soc_bus_type = {
        .name  = "soc",
};
static bool soc_bus_registered;

static DEVICE_ATTR(machine,             0444, soc_info_show,  NULL);
static DEVICE_ATTR(family,              0444, soc_info_show,  NULL);
static DEVICE_ATTR(serial_number,       0444, soc_info_show,  NULL);
static DEVICE_ATTR(soc_id,              0444, soc_info_show,  NULL);
static DEVICE_ATTR(revision,            0444, soc_info_show,  NULL);

struct device *soc_device_to_device(struct soc_device *soc_dev)
{
        return &soc_dev->dev;
}

static umode_t soc_attribute_mode(struct kobject *kobj,
                                struct attribute *attr,
                                int index)
{
        struct device *dev = kobj_to_dev(kobj);
        struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

        if ((attr == &dev_attr_machine.attr) && soc_dev->attr->machine)
                return attr->mode;
        if ((attr == &dev_attr_family.attr) && soc_dev->attr->family)
                return attr->mode;
        if ((attr == &dev_attr_revision.attr) && soc_dev->attr->revision)
                return attr->mode;
        if ((attr == &dev_attr_serial_number.attr) && soc_dev->attr->serial_number)
                return attr->mode;
        if ((attr == &dev_attr_soc_id.attr) && soc_dev->attr->soc_id)
                return attr->mode;

        /* Unknown or unfilled attribute */
        return 0;
}

static ssize_t soc_info_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
        const char *output;

        if (attr == &dev_attr_machine)
                output = soc_dev->attr->machine;
        else if (attr == &dev_attr_family)
                output = soc_dev->attr->family;
        else if (attr == &dev_attr_revision)
                output = soc_dev->attr->revision;
        else if (attr == &dev_attr_serial_number)
                output = soc_dev->attr->serial_number;
        else if (attr == &dev_attr_soc_id)
                output = soc_dev->attr->soc_id;
        else
                return -EINVAL;

        return sysfs_emit(buf, "%s\n", output);
}

static struct attribute *soc_attr[] = {
        &dev_attr_machine.attr,
        &dev_attr_family.attr,
        &dev_attr_serial_number.attr,
        &dev_attr_soc_id.attr,
        &dev_attr_revision.attr,
        NULL,
};

static const struct attribute_group soc_attr_group = {
        .attrs = soc_attr,
        .is_visible = soc_attribute_mode,
};

static void soc_release(struct device *dev)
{
        struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

        ida_free(&soc_ida, soc_dev->soc_dev_num);
        kfree(soc_dev->dev.groups);
        kfree(soc_dev);
}

static void soc_device_get_machine(struct soc_device_attribute *soc_dev_attr)
{
        struct device_node *np;

        if (soc_dev_attr->machine)
                return;

        np = of_find_node_by_path("/");
        of_property_read_string(np, "model", &soc_dev_attr->machine);
        of_node_put(np);
}

static struct soc_device_attribute *early_soc_dev_attr;

struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
{
        struct soc_device *soc_dev;
        const struct attribute_group **soc_attr_groups;
        int ret;

        soc_device_get_machine(soc_dev_attr);

        if (!soc_bus_registered) {
                if (early_soc_dev_attr)
                        return ERR_PTR(-EBUSY);
                early_soc_dev_attr = soc_dev_attr;
                return NULL;
        }

        soc_dev = kzalloc_obj(*soc_dev);
        if (!soc_dev) {
                ret = -ENOMEM;
                goto out1;
        }

        soc_attr_groups = kzalloc_objs(*soc_attr_groups, 3);
        if (!soc_attr_groups) {
                ret = -ENOMEM;
                goto out2;
        }
        soc_attr_groups[0] = &soc_attr_group;
        soc_attr_groups[1] = soc_dev_attr->custom_attr_group;

        /* Fetch a unique (reclaimable) SOC ID. */
        ret = ida_alloc(&soc_ida, GFP_KERNEL);
        if (ret < 0)
                goto out3;
        soc_dev->soc_dev_num = ret;

        soc_dev->attr = soc_dev_attr;
        soc_dev->dev.bus = &soc_bus_type;
        soc_dev->dev.groups = soc_attr_groups;
        soc_dev->dev.release = soc_release;

        dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);

        ret = device_register(&soc_dev->dev);
        if (ret) {
                put_device(&soc_dev->dev);
                return ERR_PTR(ret);
        }

        return soc_dev;

out3:
        kfree(soc_attr_groups);
out2:
        kfree(soc_dev);
out1:
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(soc_device_register);

/* Ensure soc_dev->attr is freed after calling soc_device_unregister. */
void soc_device_unregister(struct soc_device *soc_dev)
{
        device_unregister(&soc_dev->dev);
        early_soc_dev_attr = NULL;
}
EXPORT_SYMBOL_GPL(soc_device_unregister);

static int __init soc_bus_register(void)
{
        int ret;

        ret = bus_register(&soc_bus_type);
        if (ret)
                return ret;
        soc_bus_registered = true;

        if (early_soc_dev_attr)
                return PTR_ERR(soc_device_register(early_soc_dev_attr));

        return 0;
}
core_initcall(soc_bus_register);

static int soc_device_match_attr(const struct soc_device_attribute *attr,
                                 const struct soc_device_attribute *match)
{
        if (match->machine &&
            (!attr->machine || !glob_match(match->machine, attr->machine)))
                return 0;

        if (match->family &&
            (!attr->family || !glob_match(match->family, attr->family)))
                return 0;

        if (match->revision &&
            (!attr->revision || !glob_match(match->revision, attr->revision)))
                return 0;

        if (match->soc_id &&
            (!attr->soc_id || !glob_match(match->soc_id, attr->soc_id)))
                return 0;

        return 1;
}

static int soc_device_match_one(struct device *dev, void *arg)
{
        struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

        return soc_device_match_attr(soc_dev->attr, arg);
}

/*
 * soc_device_match - identify the SoC in the machine
 * @matches: zero-terminated array of possible matches
 *
 * returns the first matching entry of the argument array, or NULL
 * if none of them match.
 *
 * This function is meant as a helper in place of of_match_node()
 * in cases where either no device tree is available or the information
 * in a device node is insufficient to identify a particular variant
 * by its compatible strings or other properties. For new devices,
 * the DT binding should always provide unique compatible strings
 * that allow the use of of_match_node() instead.
 *
 * The calling function can use the .data entry of the
 * soc_device_attribute to pass a structure or function pointer for
 * each entry.
 */
const struct soc_device_attribute *soc_device_match(
        const struct soc_device_attribute *matches)
{
        int ret;

        if (!matches)
                return NULL;

        while (matches->machine || matches->family || matches->revision ||
               matches->soc_id) {
                ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
                                       soc_device_match_one);
                if (ret < 0 && early_soc_dev_attr)
                        ret = soc_device_match_attr(early_soc_dev_attr,
                                                    matches);
                if (ret < 0)
                        return NULL;
                if (ret)
                        return matches;

                matches++;
        }
        return NULL;
}
EXPORT_SYMBOL_GPL(soc_device_match);