/*
 * cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
 *
 * Copyright (C) 2014 Google, Inc.
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>

#include "cros_ec_dev.h"

/* Device variables */
#define CROS_MAX_DEV 128
static struct class *cros_class;
static int ec_major;

/* Basic communication */
static int ec_get_version(struct cros_ec_device *ec, char *str, int maxlen)
{
        struct ec_response_get_version *resp;
        static const char * const current_image_name[] = {
                "unknown", "read-only", "read-write", "invalid",
        };
        struct cros_ec_command msg = {
                .version = 0,
                .command = EC_CMD_GET_VERSION,
                .outdata = { 0 },
                .outsize = 0,
                .indata = { 0 },
                .insize = sizeof(*resp),
        };
        int ret;

        ret = cros_ec_cmd_xfer(ec, &msg);
        if (ret < 0)
                return ret;

        if (msg.result != EC_RES_SUCCESS) {
                snprintf(str, maxlen,
                         "%s\nUnknown EC version: EC returned %d\n",
                         CROS_EC_DEV_VERSION, msg.result);
                return 0;
        }

        resp = (struct ec_response_get_version *)msg.indata;
        if (resp->current_image >= ARRAY_SIZE(current_image_name))
                resp->current_image = 3; /* invalid */

        snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
                 resp->version_string_ro, resp->version_string_rw,
                 current_image_name[resp->current_image]);

        return 0;
}

/* Device file ops */
static int ec_device_open(struct inode *inode, struct file *filp)
{
        filp->private_data = container_of(inode->i_cdev,
                                          struct cros_ec_device, cdev);
        return 0;
}

static int ec_device_release(struct inode *inode, struct file *filp)
{
        return 0;
}

static ssize_t ec_device_read(struct file *filp, char __user *buffer,
                              size_t length, loff_t *offset)
{
        struct cros_ec_device *ec = filp->private_data;
        char msg[sizeof(struct ec_response_get_version) +
                 sizeof(CROS_EC_DEV_VERSION)];
        size_t count;
        int ret;

        if (*offset != 0)
                return 0;

        ret = ec_get_version(ec, msg, sizeof(msg));
        if (ret)
                return ret;

        count = min(length, strlen(msg));

        if (copy_to_user(buffer, msg, count))
                return -EFAULT;

        *offset = count;
        return count;
}

/* Ioctls */
static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
{
        long ret;
        struct cros_ec_command s_cmd = { };

        if (copy_from_user(&s_cmd, arg, sizeof(s_cmd)))
                return -EFAULT;

        ret = cros_ec_cmd_xfer(ec, &s_cmd);
        /* Only copy data to userland if data was received. */
        if (ret < 0)
                return ret;

        if (copy_to_user(arg, &s_cmd, sizeof(s_cmd)))
                return -EFAULT;

        return 0;
}

static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user *arg)
{
        struct cros_ec_readmem s_mem = { };
        long num;

        /* Not every platform supports direct reads */
        if (!ec->cmd_readmem)
                return -ENOTTY;

        if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
                return -EFAULT;

        num = ec->cmd_readmem(ec, s_mem.offset, s_mem.bytes, s_mem.buffer);
        if (num <= 0)
                return num;

        if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
                return -EFAULT;

        return 0;
}

static long ec_device_ioctl(struct file *filp, unsigned int cmd,
                            unsigned long arg)
{
        struct cros_ec_device *ec = filp->private_data;

        if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
                return -ENOTTY;

        switch (cmd) {
        case CROS_EC_DEV_IOCXCMD:
                return ec_device_ioctl_xcmd(ec, (void __user *)arg);
        case CROS_EC_DEV_IOCRDMEM:
                return ec_device_ioctl_readmem(ec, (void __user *)arg);
        }

        return -ENOTTY;
}

/* Module initialization */
static const struct file_operations fops = {
        .open = ec_device_open,
        .release = ec_device_release,
        .read = ec_device_read,
        .unlocked_ioctl = ec_device_ioctl,
};

static int ec_device_probe(struct platform_device *pdev)
{
        struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
        int retval = -ENOTTY;
        dev_t devno = MKDEV(ec_major, 0);

        /* Instantiate it (and remember the EC) */
        cdev_init(&ec->cdev, &fops);

        retval = cdev_add(&ec->cdev, devno, 1);
        if (retval) {
                dev_err(&pdev->dev, ": failed to add character device\n");
                return retval;
        }

        ec->vdev = device_create(cros_class, NULL, devno, ec,
                                 CROS_EC_DEV_NAME);
        if (IS_ERR(ec->vdev)) {
                retval = PTR_ERR(ec->vdev);
                dev_err(&pdev->dev, ": failed to create device\n");
                cdev_del(&ec->cdev);
                return retval;
        }

        /* Initialize extra interfaces */
        ec_dev_sysfs_init(ec);
        ec_dev_lightbar_init(ec);

        return 0;
}

static int ec_device_remove(struct platform_device *pdev)
{
        struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);

        ec_dev_lightbar_remove(ec);
        ec_dev_sysfs_remove(ec);
        device_destroy(cros_class, MKDEV(ec_major, 0));
        cdev_del(&ec->cdev);
        return 0;
}

static struct platform_driver cros_ec_dev_driver = {
        .driver = {
                .name = "cros-ec-ctl",
        },
        .probe = ec_device_probe,
        .remove = ec_device_remove,
};

static int __init cros_ec_dev_init(void)
{
        int ret;
        dev_t dev = 0;

        cros_class = class_create(THIS_MODULE, "chromeos");
        if (IS_ERR(cros_class)) {
                pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
                return PTR_ERR(cros_class);
        }

        /* Get a range of minor numbers (starting with 0) to work with */
        ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
        if (ret < 0) {
                pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
                goto failed_chrdevreg;
        }
        ec_major = MAJOR(dev);

        /* Register the driver */
        ret = platform_driver_register(&cros_ec_dev_driver);
        if (ret < 0) {
                pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
                goto failed_devreg;
        }
        return 0;

failed_devreg:
        unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
failed_chrdevreg:
        class_destroy(cros_class);
        return ret;
}

static void __exit cros_ec_dev_exit(void)
{
        platform_driver_unregister(&cros_ec_dev_driver);
        unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
        class_destroy(cros_class);
}

module_init(cros_ec_dev_init);
module_exit(cros_ec_dev_exit);

MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
MODULE_VERSION("1.0");
MODULE_LICENSE("GPL");