/*
 * System Control Driver
 *
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 * Copyright (C) 2012 Linaro Ltd.
 *
 * Author: Dong Aisheng <dong.aisheng@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/err.h>
#include <linux/hwspinlock.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_data/syscon.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>
#include <linux/slab.h>

static struct platform_driver syscon_driver;

static DEFINE_SPINLOCK(syscon_list_slock);
static LIST_HEAD(syscon_list);

struct syscon {
        struct device_node *np;
        struct regmap *regmap;
        struct list_head list;
};

static const struct regmap_config syscon_regmap_config = {
        .reg_bits = 32,
        .val_bits = 32,
        .reg_stride = 4,
};

static struct syscon *of_syscon_register(struct device_node *np)
{
        struct syscon *syscon;
        struct regmap *regmap;
        void __iomem *base;
        u32 reg_io_width;
        int ret;
        struct regmap_config syscon_config = syscon_regmap_config;
        struct resource res;

        if (!of_device_is_compatible(np, "syscon"))
                return ERR_PTR(-EINVAL);

        syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
        if (!syscon)
                return ERR_PTR(-ENOMEM);

        if (of_address_to_resource(np, 0, &res)) {
                ret = -ENOMEM;
                goto err_map;
        }

        base = ioremap(res.start, resource_size(&res));
        if (!base) {
                ret = -ENOMEM;
                goto err_map;
        }

        /* Parse the device's DT node for an endianness specification */
        if (of_property_read_bool(np, "big-endian"))
                syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
        else if (of_property_read_bool(np, "little-endian"))
                syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
        else if (of_property_read_bool(np, "native-endian"))
                syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;

        /*
         * search for reg-io-width property in DT. If it is not provided,
         * default to 4 bytes. regmap_init_mmio will return an error if values
         * are invalid so there is no need to check them here.
         */
        ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
        if (ret)
                reg_io_width = 4;

        ret = of_hwspin_lock_get_id(np, 0);
        if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
                syscon_config.use_hwlock = true;
                syscon_config.hwlock_id = ret;
                syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
        } else if (ret < 0) {
                switch (ret) {
                case -ENOENT:
                        /* Ignore missing hwlock, it's optional. */
                        break;
                default:
                        pr_err("Failed to retrieve valid hwlock: %d\n", ret);
                        /* fall-through */
                case -EPROBE_DEFER:
                        goto err_regmap;
                }
        }

        syscon_config.name = of_node_full_name(np);
        syscon_config.reg_stride = reg_io_width;
        syscon_config.val_bits = reg_io_width * 8;
        syscon_config.max_register = resource_size(&res) - reg_io_width;
        syscon_config.name = of_node_full_name(np);

        regmap = regmap_init_mmio(NULL, base, &syscon_config);
        if (IS_ERR(regmap)) {
                pr_err("regmap init failed\n");
                ret = PTR_ERR(regmap);
                goto err_regmap;
        }

        syscon->regmap = regmap;
        syscon->np = np;

        spin_lock(&syscon_list_slock);
        list_add_tail(&syscon->list, &syscon_list);
        spin_unlock(&syscon_list_slock);

        return syscon;

err_regmap:
        iounmap(base);
err_map:
        kfree(syscon);
        return ERR_PTR(ret);
}

struct regmap *syscon_node_to_regmap(struct device_node *np)
{
        struct syscon *entry, *syscon = NULL;

        spin_lock(&syscon_list_slock);

        list_for_each_entry(entry, &syscon_list, list)
                if (entry->np == np) {
                        syscon = entry;
                        break;
                }

        spin_unlock(&syscon_list_slock);

        if (!syscon)
                syscon = of_syscon_register(np);

        if (IS_ERR(syscon))
                return ERR_CAST(syscon);

        return syscon->regmap;
}
EXPORT_SYMBOL_GPL(syscon_node_to_regmap);

struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
{
        struct device_node *syscon_np;
        struct regmap *regmap;

        syscon_np = of_find_compatible_node(NULL, NULL, s);
        if (!syscon_np)
                return ERR_PTR(-ENODEV);

        regmap = syscon_node_to_regmap(syscon_np);
        of_node_put(syscon_np);

        return regmap;
}
EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);

static int syscon_match_pdevname(struct device *dev, void *data)
{
        return !strcmp(dev_name(dev), (const char *)data);
}

struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
{
        struct device *dev;
        struct syscon *syscon;

        dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
                                 syscon_match_pdevname);
        if (!dev)
                return ERR_PTR(-EPROBE_DEFER);

        syscon = dev_get_drvdata(dev);

        return syscon->regmap;
}
EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);

struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
                                        const char *property)
{
        struct device_node *syscon_np;
        struct regmap *regmap;

        if (property)
                syscon_np = of_parse_phandle(np, property, 0);
        else
                syscon_np = np;

        if (!syscon_np)
                return ERR_PTR(-ENODEV);

        regmap = syscon_node_to_regmap(syscon_np);
        of_node_put(syscon_np);

        return regmap;
}
EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);

static int syscon_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct syscon_platform_data *pdata = dev_get_platdata(dev);
        struct syscon *syscon;
        struct regmap_config syscon_config = syscon_regmap_config;
        struct resource *res;
        void __iomem *base;

        syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
        if (!syscon)
                return -ENOMEM;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENOENT;

        base = devm_ioremap(dev, res->start, resource_size(res));
        if (!base)
                return -ENOMEM;

        syscon_config.max_register = res->end - res->start - 3;
        if (pdata)
                syscon_config.name = pdata->label;
        syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
        if (IS_ERR(syscon->regmap)) {
                dev_err(dev, "regmap init failed\n");
                return PTR_ERR(syscon->regmap);
        }

        platform_set_drvdata(pdev, syscon);

        dev_dbg(dev, "regmap %pR registered\n", res);

        return 0;
}

static const struct platform_device_id syscon_ids[] = {
        { "syscon", },
        { }
};

static struct platform_driver syscon_driver = {
        .driver = {
                .name = "syscon",
        },
        .probe          = syscon_probe,
        .id_table       = syscon_ids,
};

static int __init syscon_init(void)
{
        return platform_driver_register(&syscon_driver);
}
postcore_initcall(syscon_init);

static void __exit syscon_exit(void)
{
        platform_driver_unregister(&syscon_driver);
}
module_exit(syscon_exit);

MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
MODULE_DESCRIPTION("System Control driver");
MODULE_LICENSE("GPL v2");