/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/spmi.h>
#include <linux/pm_runtime.h>

#include <dt-bindings/spmi/spmi.h>

static DEFINE_IDA(ctrl_ida);

static void spmi_dev_release(struct device *dev)
{
        struct spmi_device *sdev = to_spmi_device(dev);
        kfree(sdev);
}

static const struct device_type spmi_dev_type = {
        .release        = spmi_dev_release,
};

static void spmi_ctrl_release(struct device *dev)
{
        struct spmi_controller *ctrl = to_spmi_controller(dev);
        ida_simple_remove(&ctrl_ida, ctrl->nr);
        kfree(ctrl);
}

static const struct device_type spmi_ctrl_type = {
        .release        = spmi_ctrl_release,
};

static int spmi_device_match(struct device *dev, struct device_driver *drv)
{
        if (of_driver_match_device(dev, drv))
                return 1;

        if (drv->name)
                return strncmp(dev_name(dev), drv->name,
                               SPMI_NAME_SIZE) == 0;

        return 0;
}

/**
 * spmi_device_add() - add a device previously constructed via spmi_device_alloc()
 * @sdev:       spmi_device to be added
 */
int spmi_device_add(struct spmi_device *sdev)
{
        struct spmi_controller *ctrl = sdev->ctrl;
        int err;

        dev_set_name(&sdev->dev, "%d-%02x", ctrl->nr, sdev->usid);

        err = device_add(&sdev->dev);
        if (err < 0) {
                dev_err(&sdev->dev, "Can't add %s, status %d\n",
                        dev_name(&sdev->dev), err);
                goto err_device_add;
        }

        dev_dbg(&sdev->dev, "device %s registered\n", dev_name(&sdev->dev));

err_device_add:
        return err;
}
EXPORT_SYMBOL_GPL(spmi_device_add);

/**
 * spmi_device_remove(): remove an SPMI device
 * @sdev:       spmi_device to be removed
 */
void spmi_device_remove(struct spmi_device *sdev)
{
        device_unregister(&sdev->dev);
}
EXPORT_SYMBOL_GPL(spmi_device_remove);

static inline int
spmi_cmd(struct spmi_controller *ctrl, u8 opcode, u8 sid)
{
        if (!ctrl || !ctrl->cmd || ctrl->dev.type != &spmi_ctrl_type)
                return -EINVAL;

        return ctrl->cmd(ctrl, opcode, sid);
}

static inline int spmi_read_cmd(struct spmi_controller *ctrl, u8 opcode,
                                u8 sid, u16 addr, u8 *buf, size_t len)
{
        if (!ctrl || !ctrl->read_cmd || ctrl->dev.type != &spmi_ctrl_type)
                return -EINVAL;

        return ctrl->read_cmd(ctrl, opcode, sid, addr, buf, len);
}

static inline int spmi_write_cmd(struct spmi_controller *ctrl, u8 opcode,
                                 u8 sid, u16 addr, const u8 *buf, size_t len)
{
        if (!ctrl || !ctrl->write_cmd || ctrl->dev.type != &spmi_ctrl_type)
                return -EINVAL;

        return ctrl->write_cmd(ctrl, opcode, sid, addr, buf, len);
}

/**
 * spmi_register_read() - register read
 * @sdev:       SPMI device.
 * @addr:       slave register address (5-bit address).
 * @buf:        buffer to be populated with data from the Slave.
 *
 * Reads 1 byte of data from a Slave device register.
 */
int spmi_register_read(struct spmi_device *sdev, u8 addr, u8 *buf)
{
        /* 5-bit register address */
        if (addr > 0x1F)
                return -EINVAL;

        return spmi_read_cmd(sdev->ctrl, SPMI_CMD_READ, sdev->usid, addr,
                             buf, 1);
}
EXPORT_SYMBOL_GPL(spmi_register_read);

/**
 * spmi_ext_register_read() - extended register read
 * @sdev:       SPMI device.
 * @addr:       slave register address (8-bit address).
 * @buf:        buffer to be populated with data from the Slave.
 * @len:        the request number of bytes to read (up to 16 bytes).
 *
 * Reads up to 16 bytes of data from the extended register space on a
 * Slave device.
 */
int spmi_ext_register_read(struct spmi_device *sdev, u8 addr, u8 *buf,
                           size_t len)
{
        /* 8-bit register address, up to 16 bytes */
        if (len == 0 || len > 16)
                return -EINVAL;

        return spmi_read_cmd(sdev->ctrl, SPMI_CMD_EXT_READ, sdev->usid, addr,
                             buf, len);
}
EXPORT_SYMBOL_GPL(spmi_ext_register_read);

/**
 * spmi_ext_register_readl() - extended register read long
 * @sdev:       SPMI device.
 * @addr:       slave register address (16-bit address).
 * @buf:        buffer to be populated with data from the Slave.
 * @len:        the request number of bytes to read (up to 8 bytes).
 *
 * Reads up to 8 bytes of data from the extended register space on a
 * Slave device using 16-bit address.
 */
int spmi_ext_register_readl(struct spmi_device *sdev, u16 addr, u8 *buf,
                            size_t len)
{
        /* 16-bit register address, up to 8 bytes */
        if (len == 0 || len > 8)
                return -EINVAL;

        return spmi_read_cmd(sdev->ctrl, SPMI_CMD_EXT_READL, sdev->usid, addr,
                             buf, len);
}
EXPORT_SYMBOL_GPL(spmi_ext_register_readl);

/**
 * spmi_register_write() - register write
 * @sdev:       SPMI device
 * @addr:       slave register address (5-bit address).
 * @data:       buffer containing the data to be transferred to the Slave.
 *
 * Writes 1 byte of data to a Slave device register.
 */
int spmi_register_write(struct spmi_device *sdev, u8 addr, u8 data)
{
        /* 5-bit register address */
        if (addr > 0x1F)
                return -EINVAL;

        return spmi_write_cmd(sdev->ctrl, SPMI_CMD_WRITE, sdev->usid, addr,
                              &data, 1);
}
EXPORT_SYMBOL_GPL(spmi_register_write);

/**
 * spmi_register_zero_write() - register zero write
 * @sdev:       SPMI device.
 * @data:       the data to be written to register 0 (7-bits).
 *
 * Writes data to register 0 of the Slave device.
 */
int spmi_register_zero_write(struct spmi_device *sdev, u8 data)
{
        return spmi_write_cmd(sdev->ctrl, SPMI_CMD_ZERO_WRITE, sdev->usid, 0,
                              &data, 1);
}
EXPORT_SYMBOL_GPL(spmi_register_zero_write);

/**
 * spmi_ext_register_write() - extended register write
 * @sdev:       SPMI device.
 * @addr:       slave register address (8-bit address).
 * @buf:        buffer containing the data to be transferred to the Slave.
 * @len:        the request number of bytes to read (up to 16 bytes).
 *
 * Writes up to 16 bytes of data to the extended register space of a
 * Slave device.
 */
int spmi_ext_register_write(struct spmi_device *sdev, u8 addr, const u8 *buf,
                            size_t len)
{
        /* 8-bit register address, up to 16 bytes */
        if (len == 0 || len > 16)
                return -EINVAL;

        return spmi_write_cmd(sdev->ctrl, SPMI_CMD_EXT_WRITE, sdev->usid, addr,
                              buf, len);
}
EXPORT_SYMBOL_GPL(spmi_ext_register_write);

/**
 * spmi_ext_register_writel() - extended register write long
 * @sdev:       SPMI device.
 * @addr:       slave register address (16-bit address).
 * @buf:        buffer containing the data to be transferred to the Slave.
 * @len:        the request number of bytes to read (up to 8 bytes).
 *
 * Writes up to 8 bytes of data to the extended register space of a
 * Slave device using 16-bit address.
 */
int spmi_ext_register_writel(struct spmi_device *sdev, u16 addr, const u8 *buf,
                             size_t len)
{
        /* 4-bit Slave Identifier, 16-bit register address, up to 8 bytes */
        if (len == 0 || len > 8)
                return -EINVAL;

        return spmi_write_cmd(sdev->ctrl, SPMI_CMD_EXT_WRITEL, sdev->usid,
                              addr, buf, len);
}
EXPORT_SYMBOL_GPL(spmi_ext_register_writel);

/**
 * spmi_command_reset() - sends RESET command to the specified slave
 * @sdev:       SPMI device.
 *
 * The Reset command initializes the Slave and forces all registers to
 * their reset values. The Slave shall enter the STARTUP state after
 * receiving a Reset command.
 */
int spmi_command_reset(struct spmi_device *sdev)
{
        return spmi_cmd(sdev->ctrl, SPMI_CMD_RESET, sdev->usid);
}
EXPORT_SYMBOL_GPL(spmi_command_reset);

/**
 * spmi_command_sleep() - sends SLEEP command to the specified SPMI device
 * @sdev:       SPMI device.
 *
 * The Sleep command causes the Slave to enter the user defined SLEEP state.
 */
int spmi_command_sleep(struct spmi_device *sdev)
{
        return spmi_cmd(sdev->ctrl, SPMI_CMD_SLEEP, sdev->usid);
}
EXPORT_SYMBOL_GPL(spmi_command_sleep);

/**
 * spmi_command_wakeup() - sends WAKEUP command to the specified SPMI device
 * @sdev:       SPMI device.
 *
 * The Wakeup command causes the Slave to move from the SLEEP state to
 * the ACTIVE state.
 */
int spmi_command_wakeup(struct spmi_device *sdev)
{
        return spmi_cmd(sdev->ctrl, SPMI_CMD_WAKEUP, sdev->usid);
}
EXPORT_SYMBOL_GPL(spmi_command_wakeup);

/**
 * spmi_command_shutdown() - sends SHUTDOWN command to the specified SPMI device
 * @sdev:       SPMI device.
 *
 * The Shutdown command causes the Slave to enter the SHUTDOWN state.
 */
int spmi_command_shutdown(struct spmi_device *sdev)
{
        return spmi_cmd(sdev->ctrl, SPMI_CMD_SHUTDOWN, sdev->usid);
}
EXPORT_SYMBOL_GPL(spmi_command_shutdown);

static int spmi_drv_probe(struct device *dev)
{
        const struct spmi_driver *sdrv = to_spmi_driver(dev->driver);
        struct spmi_device *sdev = to_spmi_device(dev);
        int err;

        /* Ensure the slave is in ACTIVE state */
        err = spmi_command_wakeup(sdev);
        if (err)
                goto fail_wakeup;

        pm_runtime_get_noresume(dev);
        pm_runtime_set_active(dev);
        pm_runtime_enable(dev);

        err = sdrv->probe(sdev);
        if (err)
                goto fail_probe;

        return 0;

fail_probe:
        pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);
        pm_runtime_put_noidle(dev);
fail_wakeup:
        return err;
}

static int spmi_drv_remove(struct device *dev)
{
        const struct spmi_driver *sdrv = to_spmi_driver(dev->driver);

        pm_runtime_get_sync(dev);
        sdrv->remove(to_spmi_device(dev));
        pm_runtime_put_noidle(dev);

        pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);
        pm_runtime_put_noidle(dev);
        return 0;
}

static struct bus_type spmi_bus_type = {
        .name           = "spmi",
        .match          = spmi_device_match,
        .probe          = spmi_drv_probe,
        .remove         = spmi_drv_remove,
};

/**
 * spmi_controller_alloc() - Allocate a new SPMI device
 * @ctrl:       associated controller
 *
 * Caller is responsible for either calling spmi_device_add() to add the
 * newly allocated controller, or calling spmi_device_put() to discard it.
 */
struct spmi_device *spmi_device_alloc(struct spmi_controller *ctrl)
{
        struct spmi_device *sdev;

        sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
        if (!sdev)
                return NULL;

        sdev->ctrl = ctrl;
        device_initialize(&sdev->dev);
        sdev->dev.parent = &ctrl->dev;
        sdev->dev.bus = &spmi_bus_type;
        sdev->dev.type = &spmi_dev_type;
        return sdev;
}
EXPORT_SYMBOL_GPL(spmi_device_alloc);

/**
 * spmi_controller_alloc() - Allocate a new SPMI controller
 * @parent:     parent device
 * @size:       size of private data
 *
 * Caller is responsible for either calling spmi_controller_add() to add the
 * newly allocated controller, or calling spmi_controller_put() to discard it.
 * The allocated private data region may be accessed via
 * spmi_controller_get_drvdata()
 */
struct spmi_controller *spmi_controller_alloc(struct device *parent,
                                              size_t size)
{
        struct spmi_controller *ctrl;
        int id;

        if (WARN_ON(!parent))
                return NULL;

        ctrl = kzalloc(sizeof(*ctrl) + size, GFP_KERNEL);
        if (!ctrl)
                return NULL;

        device_initialize(&ctrl->dev);
        ctrl->dev.type = &spmi_ctrl_type;
        ctrl->dev.bus = &spmi_bus_type;
        ctrl->dev.parent = parent;
        ctrl->dev.of_node = parent->of_node;
        spmi_controller_set_drvdata(ctrl, &ctrl[1]);

        id = ida_simple_get(&ctrl_ida, 0, 0, GFP_KERNEL);
        if (id < 0) {
                dev_err(parent,
                        "unable to allocate SPMI controller identifier.\n");
                spmi_controller_put(ctrl);
                return NULL;
        }

        ctrl->nr = id;
        dev_set_name(&ctrl->dev, "spmi-%d", id);

        dev_dbg(&ctrl->dev, "allocated controller 0x%p id %d\n", ctrl, id);
        return ctrl;
}
EXPORT_SYMBOL_GPL(spmi_controller_alloc);

static void of_spmi_register_devices(struct spmi_controller *ctrl)
{
        struct device_node *node;
        int err;

        if (!ctrl->dev.of_node)
                return;

        for_each_available_child_of_node(ctrl->dev.of_node, node) {
                struct spmi_device *sdev;
                u32 reg[2];

                dev_dbg(&ctrl->dev, "adding child %s\n", node->full_name);

                err = of_property_read_u32_array(node, "reg", reg, 2);
                if (err) {
                        dev_err(&ctrl->dev,
                                "node %s err (%d) does not have 'reg' property\n",
                                node->full_name, err);
                        continue;
                }

                if (reg[1] != SPMI_USID) {
                        dev_err(&ctrl->dev,
                                "node %s contains unsupported 'reg' entry\n",
                                node->full_name);
                        continue;
                }

                if (reg[0] >= SPMI_MAX_SLAVE_ID) {
                        dev_err(&ctrl->dev,
                                "invalid usid on node %s\n",
                                node->full_name);
                        continue;
                }

                dev_dbg(&ctrl->dev, "read usid %02x\n", reg[0]);

                sdev = spmi_device_alloc(ctrl);
                if (!sdev)
                        continue;

                sdev->dev.of_node = node;
                sdev->usid = (u8) reg[0];

                err = spmi_device_add(sdev);
                if (err) {
                        dev_err(&sdev->dev,
                                "failure adding device. status %d\n", err);
                        spmi_device_put(sdev);
                }
        }
}

/**
 * spmi_controller_add() - Add an SPMI controller
 * @ctrl:       controller to be registered.
 *
 * Register a controller previously allocated via spmi_controller_alloc() with
 * the SPMI core.
 */
int spmi_controller_add(struct spmi_controller *ctrl)
{
        int ret;

        /* Can't register until after driver model init */
        if (WARN_ON(!spmi_bus_type.p))
                return -EAGAIN;

        ret = device_add(&ctrl->dev);
        if (ret)
                return ret;

        if (IS_ENABLED(CONFIG_OF))
                of_spmi_register_devices(ctrl);

        dev_dbg(&ctrl->dev, "spmi-%d registered: dev:%p\n",
                ctrl->nr, &ctrl->dev);

        return 0;
};
EXPORT_SYMBOL_GPL(spmi_controller_add);

/* Remove a device associated with a controller */
static int spmi_ctrl_remove_device(struct device *dev, void *data)
{
        struct spmi_device *spmidev = to_spmi_device(dev);
        if (dev->type == &spmi_dev_type)
                spmi_device_remove(spmidev);
        return 0;
}

/**
 * spmi_controller_remove(): remove an SPMI controller
 * @ctrl:       controller to remove
 *
 * Remove a SPMI controller.  Caller is responsible for calling
 * spmi_controller_put() to discard the allocated controller.
 */
void spmi_controller_remove(struct spmi_controller *ctrl)
{
        int dummy;

        if (!ctrl)
                return;

        dummy = device_for_each_child(&ctrl->dev, NULL,
                                      spmi_ctrl_remove_device);
        device_del(&ctrl->dev);
}
EXPORT_SYMBOL_GPL(spmi_controller_remove);

/**
 * spmi_driver_register() - Register client driver with SPMI core
 * @sdrv:       client driver to be associated with client-device.
 *
 * This API will register the client driver with the SPMI framework.
 * It is typically called from the driver's module-init function.
 */
int spmi_driver_register(struct spmi_driver *sdrv)
{
        sdrv->driver.bus = &spmi_bus_type;
        return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(spmi_driver_register);

static void __exit spmi_exit(void)
{
        bus_unregister(&spmi_bus_type);
}
module_exit(spmi_exit);

static int __init spmi_init(void)
{
        return bus_register(&spmi_bus_type);
}
postcore_initcall(spmi_init);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("SPMI module");
MODULE_ALIAS("platform:spmi");