// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2016-2017 Linaro Ltd., Rob Herring <robh@kernel.org>
 *
 * Based on drivers/spmi/spmi.c:
 * Copyright (c) 2012-2015, The Linux Foundation. All rights reserved.
 */

#include <linux/acpi.h>
#include <linux/errno.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/serdev.h>
#include <linux/slab.h>

static bool is_registered;
static DEFINE_IDA(ctrl_ida);

static ssize_t modalias_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        int len;

        len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
        if (len != -ENODEV)
                return len;

        return of_device_modalias(dev, buf, PAGE_SIZE);
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *serdev_device_attrs[] = {
        &dev_attr_modalias.attr,
        NULL,
};
ATTRIBUTE_GROUPS(serdev_device);

static int serdev_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        int rc;

        /* TODO: platform modalias */

        rc = acpi_device_uevent_modalias(dev, env);
        if (rc != -ENODEV)
                return rc;

        return of_device_uevent_modalias(dev, env);
}

static void serdev_device_release(struct device *dev)
{
        struct serdev_device *serdev = to_serdev_device(dev);
        kfree(serdev);
}

static const struct device_type serdev_device_type = {
        .groups         = serdev_device_groups,
        .uevent         = serdev_device_uevent,
        .release        = serdev_device_release,
};

static bool is_serdev_device(const struct device *dev)
{
        return dev->type == &serdev_device_type;
}

static void serdev_ctrl_release(struct device *dev)
{
        struct serdev_controller *ctrl = to_serdev_controller(dev);
        ida_simple_remove(&ctrl_ida, ctrl->nr);
        kfree(ctrl);
}

static const struct device_type serdev_ctrl_type = {
        .release        = serdev_ctrl_release,
};

static int serdev_device_match(struct device *dev, struct device_driver *drv)
{
        if (!is_serdev_device(dev))
                return 0;

        /* TODO: platform matching */
        if (acpi_driver_match_device(dev, drv))
                return 1;

        return of_driver_match_device(dev, drv);
}

/**
 * serdev_device_add() - add a device previously constructed via serdev_device_alloc()
 * @serdev:     serdev_device to be added
 */
int serdev_device_add(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;
        struct device *parent = serdev->dev.parent;
        int err;

        dev_set_name(&serdev->dev, "%s-%d", dev_name(parent), serdev->nr);

        /* Only a single slave device is currently supported. */
        if (ctrl->serdev) {
                dev_err(&serdev->dev, "controller busy\n");
                return -EBUSY;
        }
        ctrl->serdev = serdev;

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

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

        return 0;

err_clear_serdev:
        ctrl->serdev = NULL;
        return err;
}
EXPORT_SYMBOL_GPL(serdev_device_add);

/**
 * serdev_device_remove(): remove an serdev device
 * @serdev:     serdev_device to be removed
 */
void serdev_device_remove(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        device_unregister(&serdev->dev);
        ctrl->serdev = NULL;
}
EXPORT_SYMBOL_GPL(serdev_device_remove);

int serdev_device_open(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;
        int ret;

        if (!ctrl || !ctrl->ops->open)
                return -EINVAL;

        ret = ctrl->ops->open(ctrl);
        if (ret)
                return ret;

        ret = pm_runtime_get_sync(&ctrl->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(&ctrl->dev);
                goto err_close;
        }

        return 0;

err_close:
        if (ctrl->ops->close)
                ctrl->ops->close(ctrl);

        return ret;
}
EXPORT_SYMBOL_GPL(serdev_device_open);

void serdev_device_close(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->close)
                return;

        pm_runtime_put(&ctrl->dev);

        ctrl->ops->close(ctrl);
}
EXPORT_SYMBOL_GPL(serdev_device_close);

static void devm_serdev_device_release(struct device *dev, void *dr)
{
        serdev_device_close(*(struct serdev_device **)dr);
}

int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
{
        struct serdev_device **dr;
        int ret;

        dr = devres_alloc(devm_serdev_device_release, sizeof(*dr), GFP_KERNEL);
        if (!dr)
                return -ENOMEM;

        ret = serdev_device_open(serdev);
        if (ret) {
                devres_free(dr);
                return ret;
        }

        *dr = serdev;
        devres_add(dev, dr);

        return 0;
}
EXPORT_SYMBOL_GPL(devm_serdev_device_open);

void serdev_device_write_wakeup(struct serdev_device *serdev)
{
        complete(&serdev->write_comp);
}
EXPORT_SYMBOL_GPL(serdev_device_write_wakeup);

/**
 * serdev_device_write_buf() - write data asynchronously
 * @serdev:     serdev device
 * @buf:        data to be written
 * @count:      number of bytes to write
 *
 * Write data to the device asynchronously.
 *
 * Note that any accepted data has only been buffered by the controller; use
 * serdev_device_wait_until_sent() to make sure the controller write buffer
 * has actually been emptied.
 *
 * Return: The number of bytes written (less than count if not enough room in
 * the write buffer), or a negative errno on errors.
 */
int serdev_device_write_buf(struct serdev_device *serdev,
                            const unsigned char *buf, size_t count)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->write_buf)
                return -EINVAL;

        return ctrl->ops->write_buf(ctrl, buf, count);
}
EXPORT_SYMBOL_GPL(serdev_device_write_buf);

/**
 * serdev_device_write() - write data synchronously
 * @serdev:     serdev device
 * @buf:        data to be written
 * @count:      number of bytes to write
 * @timeout:    timeout in jiffies, or 0 to wait indefinitely
 *
 * Write data to the device synchronously by repeatedly calling
 * serdev_device_write() until the controller has accepted all data (unless
 * interrupted by a timeout or a signal).
 *
 * Note that any accepted data has only been buffered by the controller; use
 * serdev_device_wait_until_sent() to make sure the controller write buffer
 * has actually been emptied.
 *
 * Note that this function depends on serdev_device_write_wakeup() being
 * called in the serdev driver write_wakeup() callback.
 *
 * Return: The number of bytes written (less than count if interrupted),
 * -ETIMEDOUT or -ERESTARTSYS if interrupted before any bytes were written, or
 * a negative errno on errors.
 */
int serdev_device_write(struct serdev_device *serdev,
                        const unsigned char *buf, size_t count,
                        long timeout)
{
        struct serdev_controller *ctrl = serdev->ctrl;
        int written = 0;
        int ret;

        if (!ctrl || !ctrl->ops->write_buf || !serdev->ops->write_wakeup)
                return -EINVAL;

        if (timeout == 0)
                timeout = MAX_SCHEDULE_TIMEOUT;

        mutex_lock(&serdev->write_lock);
        do {
                reinit_completion(&serdev->write_comp);

                ret = ctrl->ops->write_buf(ctrl, buf, count);
                if (ret < 0)
                        break;

                written += ret;
                buf += ret;
                count -= ret;

                if (count == 0)
                        break;

                timeout = wait_for_completion_interruptible_timeout(&serdev->write_comp,
                                                                    timeout);
        } while (timeout > 0);
        mutex_unlock(&serdev->write_lock);

        if (ret < 0)
                return ret;

        if (timeout <= 0 && written == 0) {
                if (timeout == -ERESTARTSYS)
                        return -ERESTARTSYS;
                else
                        return -ETIMEDOUT;
        }

        return written;
}
EXPORT_SYMBOL_GPL(serdev_device_write);

void serdev_device_write_flush(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->write_flush)
                return;

        ctrl->ops->write_flush(ctrl);
}
EXPORT_SYMBOL_GPL(serdev_device_write_flush);

int serdev_device_write_room(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->write_room)
                return 0;

        return serdev->ctrl->ops->write_room(ctrl);
}
EXPORT_SYMBOL_GPL(serdev_device_write_room);

unsigned int serdev_device_set_baudrate(struct serdev_device *serdev, unsigned int speed)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->set_baudrate)
                return 0;

        return ctrl->ops->set_baudrate(ctrl, speed);

}
EXPORT_SYMBOL_GPL(serdev_device_set_baudrate);

void serdev_device_set_flow_control(struct serdev_device *serdev, bool enable)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->set_flow_control)
                return;

        ctrl->ops->set_flow_control(ctrl, enable);
}
EXPORT_SYMBOL_GPL(serdev_device_set_flow_control);

int serdev_device_set_parity(struct serdev_device *serdev,
                             enum serdev_parity parity)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->set_parity)
                return -ENOTSUPP;

        return ctrl->ops->set_parity(ctrl, parity);
}
EXPORT_SYMBOL_GPL(serdev_device_set_parity);

void serdev_device_wait_until_sent(struct serdev_device *serdev, long timeout)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->wait_until_sent)
                return;

        ctrl->ops->wait_until_sent(ctrl, timeout);
}
EXPORT_SYMBOL_GPL(serdev_device_wait_until_sent);

int serdev_device_get_tiocm(struct serdev_device *serdev)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->get_tiocm)
                return -ENOTSUPP;

        return ctrl->ops->get_tiocm(ctrl);
}
EXPORT_SYMBOL_GPL(serdev_device_get_tiocm);

int serdev_device_set_tiocm(struct serdev_device *serdev, int set, int clear)
{
        struct serdev_controller *ctrl = serdev->ctrl;

        if (!ctrl || !ctrl->ops->set_tiocm)
                return -ENOTSUPP;

        return ctrl->ops->set_tiocm(ctrl, set, clear);
}
EXPORT_SYMBOL_GPL(serdev_device_set_tiocm);

static int serdev_drv_probe(struct device *dev)
{
        const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
        int ret;

        ret = dev_pm_domain_attach(dev, true);
        if (ret)
                return ret;

        ret = sdrv->probe(to_serdev_device(dev));
        if (ret)
                dev_pm_domain_detach(dev, true);

        return ret;
}

static int serdev_drv_remove(struct device *dev)
{
        const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
        if (sdrv->remove)
                sdrv->remove(to_serdev_device(dev));

        dev_pm_domain_detach(dev, true);

        return 0;
}

static struct bus_type serdev_bus_type = {
        .name           = "serial",
        .match          = serdev_device_match,
        .probe          = serdev_drv_probe,
        .remove         = serdev_drv_remove,
};

/**
 * serdev_device_alloc() - Allocate a new serdev device
 * @ctrl:       associated controller
 *
 * Caller is responsible for either calling serdev_device_add() to add the
 * newly allocated controller, or calling serdev_device_put() to discard it.
 */
struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
{
        struct serdev_device *serdev;

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

        serdev->ctrl = ctrl;
        device_initialize(&serdev->dev);
        serdev->dev.parent = &ctrl->dev;
        serdev->dev.bus = &serdev_bus_type;
        serdev->dev.type = &serdev_device_type;
        init_completion(&serdev->write_comp);
        mutex_init(&serdev->write_lock);
        return serdev;
}
EXPORT_SYMBOL_GPL(serdev_device_alloc);

/**
 * serdev_controller_alloc() - Allocate a new serdev controller
 * @parent:     parent device
 * @size:       size of private data
 *
 * Caller is responsible for either calling serdev_controller_add() to add the
 * newly allocated controller, or calling serdev_controller_put() to discard it.
 * The allocated private data region may be accessed via
 * serdev_controller_get_drvdata()
 */
struct serdev_controller *serdev_controller_alloc(struct device *parent,
                                              size_t size)
{
        struct serdev_controller *ctrl;
        int id;

        if (WARN_ON(!parent))
                return NULL;

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

        id = ida_simple_get(&ctrl_ida, 0, 0, GFP_KERNEL);
        if (id < 0) {
                dev_err(parent,
                        "unable to allocate serdev controller identifier.\n");
                goto err_free;
        }

        ctrl->nr = id;

        device_initialize(&ctrl->dev);
        ctrl->dev.type = &serdev_ctrl_type;
        ctrl->dev.bus = &serdev_bus_type;
        ctrl->dev.parent = parent;
        ctrl->dev.of_node = parent->of_node;
        serdev_controller_set_drvdata(ctrl, &ctrl[1]);

        dev_set_name(&ctrl->dev, "serial%d", id);

        pm_runtime_no_callbacks(&ctrl->dev);
        pm_suspend_ignore_children(&ctrl->dev, true);

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

err_free:
        kfree(ctrl);

        return NULL;
}
EXPORT_SYMBOL_GPL(serdev_controller_alloc);

static int of_serdev_register_devices(struct serdev_controller *ctrl)
{
        struct device_node *node;
        struct serdev_device *serdev = NULL;
        int err;
        bool found = false;

        for_each_available_child_of_node(ctrl->dev.of_node, node) {
                if (!of_get_property(node, "compatible", NULL))
                        continue;

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

                serdev = serdev_device_alloc(ctrl);
                if (!serdev)
                        continue;

                serdev->dev.of_node = node;

                err = serdev_device_add(serdev);
                if (err) {
                        dev_err(&serdev->dev,
                                "failure adding device. status %d\n", err);
                        serdev_device_put(serdev);
                } else
                        found = true;
        }
        if (!found)
                return -ENODEV;

        return 0;
}

#ifdef CONFIG_ACPI
static acpi_status acpi_serdev_register_device(struct serdev_controller *ctrl,
                                            struct acpi_device *adev)
{
        struct serdev_device *serdev = NULL;
        int err;

        if (acpi_bus_get_status(adev) || !adev->status.present ||
            acpi_device_enumerated(adev))
                return AE_OK;

        serdev = serdev_device_alloc(ctrl);
        if (!serdev) {
                dev_err(&ctrl->dev, "failed to allocate serdev device for %s\n",
                        dev_name(&adev->dev));
                return AE_NO_MEMORY;
        }

        ACPI_COMPANION_SET(&serdev->dev, adev);
        acpi_device_set_enumerated(adev);

        err = serdev_device_add(serdev);
        if (err) {
                dev_err(&serdev->dev,
                        "failure adding ACPI serdev device. status %d\n", err);
                serdev_device_put(serdev);
        }

        return AE_OK;
}

static acpi_status acpi_serdev_add_device(acpi_handle handle, u32 level,
                                       void *data, void **return_value)
{
        struct serdev_controller *ctrl = data;
        struct acpi_device *adev;

        if (acpi_bus_get_device(handle, &adev))
                return AE_OK;

        return acpi_serdev_register_device(ctrl, adev);
}

static int acpi_serdev_register_devices(struct serdev_controller *ctrl)
{
        acpi_status status;
        acpi_handle handle;

        handle = ACPI_HANDLE(ctrl->dev.parent);
        if (!handle)
                return -ENODEV;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
                                     acpi_serdev_add_device, NULL, ctrl, NULL);
        if (ACPI_FAILURE(status))
                dev_dbg(&ctrl->dev, "failed to enumerate serdev slaves\n");

        if (!ctrl->serdev)
                return -ENODEV;

        return 0;
}
#else
static inline int acpi_serdev_register_devices(struct serdev_controller *ctrl)
{
        return -ENODEV;
}
#endif /* CONFIG_ACPI */

/**
 * serdev_controller_add() - Add an serdev controller
 * @ctrl:       controller to be registered.
 *
 * Register a controller previously allocated via serdev_controller_alloc() with
 * the serdev core.
 */
int serdev_controller_add(struct serdev_controller *ctrl)
{
        int ret_of, ret_acpi, ret;

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

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

        pm_runtime_enable(&ctrl->dev);

        ret_of = of_serdev_register_devices(ctrl);
        ret_acpi = acpi_serdev_register_devices(ctrl);
        if (ret_of && ret_acpi) {
                dev_dbg(&ctrl->dev, "no devices registered: of:%d acpi:%d\n",
                        ret_of, ret_acpi);
                ret = -ENODEV;
                goto err_rpm_disable;
        }

        dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n",
                ctrl->nr, &ctrl->dev);
        return 0;

err_rpm_disable:
        pm_runtime_disable(&ctrl->dev);
        device_del(&ctrl->dev);
        return ret;
};
EXPORT_SYMBOL_GPL(serdev_controller_add);

/* Remove a device associated with a controller */
static int serdev_remove_device(struct device *dev, void *data)
{
        struct serdev_device *serdev = to_serdev_device(dev);
        if (dev->type == &serdev_device_type)
                serdev_device_remove(serdev);
        return 0;
}

/**
 * serdev_controller_remove(): remove an serdev controller
 * @ctrl:       controller to remove
 *
 * Remove a serdev controller.  Caller is responsible for calling
 * serdev_controller_put() to discard the allocated controller.
 */
void serdev_controller_remove(struct serdev_controller *ctrl)
{
        int dummy;

        if (!ctrl)
                return;

        dummy = device_for_each_child(&ctrl->dev, NULL,
                                      serdev_remove_device);
        pm_runtime_disable(&ctrl->dev);
        device_del(&ctrl->dev);
}
EXPORT_SYMBOL_GPL(serdev_controller_remove);

/**
 * serdev_driver_register() - Register client driver with serdev core
 * @sdrv:       client driver to be associated with client-device.
 *
 * This API will register the client driver with the serdev framework.
 * It is typically called from the driver's module-init function.
 */
int __serdev_device_driver_register(struct serdev_device_driver *sdrv, struct module *owner)
{
        sdrv->driver.bus = &serdev_bus_type;
        sdrv->driver.owner = owner;

        /* force drivers to async probe so I/O is possible in probe */
        sdrv->driver.probe_type = PROBE_PREFER_ASYNCHRONOUS;

        return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(__serdev_device_driver_register);

static void __exit serdev_exit(void)
{
        bus_unregister(&serdev_bus_type);
        ida_destroy(&ctrl_ida);
}
module_exit(serdev_exit);

static int __init serdev_init(void)
{
        int ret;

        ret = bus_register(&serdev_bus_type);
        if (ret)
                return ret;

        is_registered = true;
        return 0;
}
/* Must be before serial drivers register */
postcore_initcall(serdev_init);

MODULE_AUTHOR("Rob Herring <robh@kernel.org>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Serial attached device bus");