// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2015-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.

#include <nvidia/conftest.h>

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/i2c.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/version.h>
#include <media/isc-dev.h>
#include <uapi/media/isc-mgr.h>

#include "isc-dev-priv.h"
#include "isc-mgr-priv.h"

/* i2c payload size is only 12 bit */
#define MAX_MSG_SIZE	(0xFFF - 1)

/*#define DEBUG_I2C_TRAFFIC*/

/* ISC Dev Debugfs functions
 *
 *    - isc_dev_debugfs_init
 *    - isc_dev_debugfs_remove
 *    - i2c_oft_get
 *    - i2c_oft_set
 *    - i2c_val_get
 *    - i2c_oft_set
 */
static int i2c_val_get(void *data, u64 *val)
{
	struct isc_dev_info *isc_dev = data;
	u8 temp = 0;

	if (isc_dev_raw_rd(isc_dev, isc_dev->reg_off, 0, &temp, 1)) {
		dev_err(isc_dev->dev, "ERR:%s failed\n", __func__);
		return -EIO;
	}
	*val = (u64)temp;
	return 0;
}

static int i2c_val_set(void *data, u64 val)
{
	struct isc_dev_info *isc_dev = data;
	u8 temp[3];

	temp[2] = val & 0xff;
	if (isc_dev_raw_wr(isc_dev, isc_dev->reg_off, temp, 1)) {
		dev_err(isc_dev->dev, "ERR:%s failed\n", __func__);
		return -EIO;
	}
	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(isc_val_fops, i2c_val_get, i2c_val_set, "0x%02llx\n");

static int i2c_oft_get(void *data, u64 *val)
{
	struct isc_dev_info *isc_dev = data;

	*val = (u64)isc_dev->reg_off;
	return 0;
}

static int i2c_oft_set(void *data, u64 val)
{
	struct isc_dev_info *isc_dev = data;

	isc_dev->reg_off = (typeof(isc_dev->reg_off))val;
	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(isc_oft_fops, i2c_oft_get, i2c_oft_set, "0x%02llx\n");

int isc_dev_debugfs_init(struct isc_dev_info *isc_dev)
{
	struct isc_mgr_priv *isc_mgr = NULL;
	struct dentry *d;

	dev_dbg(isc_dev->dev, "%s %s\n", __func__, isc_dev->devname);

	if (isc_dev->pdata)
		isc_mgr = dev_get_drvdata(isc_dev->pdata->pdev);

	isc_dev->d_entry = debugfs_create_dir(
		isc_dev->devname,
		isc_mgr ? isc_mgr->d_entry : NULL);
	if (isc_dev->d_entry == NULL) {
		dev_err(isc_dev->dev, "%s: create dir failed\n", __func__);
		return -ENOMEM;
	}

	d = debugfs_create_file("val", S_IRUGO|S_IWUSR, isc_dev->d_entry,
		(void *)isc_dev, &isc_val_fops);
	if (!d) {
		dev_err(isc_dev->dev, "%s: create file failed\n", __func__);
		debugfs_remove_recursive(isc_dev->d_entry);
		isc_dev->d_entry = NULL;
	}

	d = debugfs_create_file("offset", S_IRUGO|S_IWUSR, isc_dev->d_entry,
		(void *)isc_dev, &isc_oft_fops);
	if (!d) {
		dev_err(isc_dev->dev, "%s: create file failed\n", __func__);
		debugfs_remove_recursive(isc_dev->d_entry);
		isc_dev->d_entry = NULL;
	}

	return 0;
}

int isc_dev_debugfs_remove(struct isc_dev_info *isc_dev)
{
	if (isc_dev->d_entry == NULL)
		return 0;
	debugfs_remove_recursive(isc_dev->d_entry);
	isc_dev->d_entry = NULL;
	return 0;
}

static void isc_dev_dump(
	const char *str,
	struct isc_dev_info *info,
	unsigned int offset,
	u8 *buf, size_t size)
{
#if (defined(DEBUG) || defined(DEBUG_I2C_TRAFFIC))
	char *dump_buf;
	int len, i, off;

	/* alloc enough memory for function name + offset + data */
	len = strlen(str) + size * 3 + 10;
	dump_buf = kzalloc(len, GFP_KERNEL);
	if (dump_buf == NULL) {
		dev_err(info->dev, "%s: Memory alloc ERROR!\n", __func__);
		return;
	}

	off = sprintf(dump_buf, "%s %04x =", str, offset);
	for (i = 0; i < size && off < len - 1; i++)
		off += sprintf(dump_buf + off, " %02x", buf[i]);
	dump_buf[off] = 0;
	dev_notice(info->dev, "%s\n", dump_buf);
	kfree(dump_buf);
#endif
}

/* i2c read from device.
 *  val    - buffer contains data to write.
 *  size   - number of bytes to be written to device.
 *  offset - address in the device's register space to start with.
 */
int isc_dev_raw_rd(
	struct isc_dev_info *info, unsigned int offset,
	unsigned int offset_len, u8 *val, size_t size)
{
	int ret = -ENODEV;
	u8 data[2];
	struct i2c_msg i2cmsg[2];

	dev_dbg(info->dev, "%s\n", __func__);
	mutex_lock(&info->mutex);
	if (!info->power_is_on) {
		dev_err(info->dev, "%s: power is off.\n", __func__);
		mutex_unlock(&info->mutex);
		return ret;
	}

	/* when user read device from debugfs, the offset_len will be 0.
	 * And the offset_len should come from device info
	 */
	if (!offset_len)
		offset_len = info->reg_len;

	if (offset_len == 2) {
		data[0] = (u8)((offset >> 8) & 0xff);
		data[1] = (u8)(offset & 0xff);
	} else if (offset_len == 1)
		data[0] = (u8)(offset & 0xff);

	i2cmsg[0].addr = info->i2c_client->addr;
	i2cmsg[0].len = offset_len;
	i2cmsg[0].buf = (__u8 *)data;
	i2cmsg[0].flags = I2C_M_NOSTART;

	i2cmsg[1].addr = info->i2c_client->addr;
	i2cmsg[1].flags = I2C_M_RD;
	i2cmsg[1].len = size;
	i2cmsg[1].buf = (__u8 *)val;

	ret = i2c_transfer(info->i2c_client->adapter, i2cmsg, 2);
	if (ret > 0)
		ret = 0;
	mutex_unlock(&info->mutex);

	if (!ret)
		isc_dev_dump(__func__, info, offset, val, size);

	return ret;
}

/* i2c write to device.
 * val    - buffer contains data to write.
 * size   - number of bytes to be written to device.
 * offset - address in the device's register space to start with.
 *		if offset == -1, it will be ignored and no offset
 *		value will be integrated into the data buffer.
 */
int isc_dev_raw_wr(
	struct isc_dev_info *info, unsigned int offset, u8 *val, size_t size)
{
	int ret = -ENODEV;
	u8 *buf_start = NULL;
	struct i2c_msg *i2cmsg;
	unsigned int num_msgs = 0, total_size, i;

	dev_dbg(info->dev, "%s\n", __func__);
	mutex_lock(&info->mutex);

	if (size == 0) {
		dev_dbg(info->dev, "%s: size is 0.\n", __func__);
		mutex_unlock(&info->mutex);
		return 0;
	}

	if (!info->power_is_on) {
		dev_err(info->dev, "%s: power is off.\n", __func__);
		mutex_unlock(&info->mutex);
		return ret;
	}

	if (offset != (unsigned int)-1) { /* offset is valid */
		if (info->reg_len == 2) {
			val[0] = (u8)((offset >> 8) & 0xff);
			val[1] = (u8)(offset & 0xff);
			size += 2;
		} else if (info->reg_len == 1) {
			val++;
			val[0] = (u8)(offset & 0xff);
			size += 1;
		} else
			val += 2;
	}

	isc_dev_dump(__func__, info, offset, val, size);

	num_msgs = size / MAX_MSG_SIZE;
	num_msgs += (size % MAX_MSG_SIZE) ? 1 : 0;

	i2cmsg = kzalloc((sizeof(struct i2c_msg)*num_msgs), GFP_KERNEL);
	if (!i2cmsg) {
		dev_err(info->dev, "%s: failed to allocate memory\n",
			__func__);
		mutex_unlock(&info->mutex);
		return -ENOMEM;
	}

	buf_start = val;
	total_size = size;

	dev_dbg(info->dev, "%s: num_msgs: %d\n", __func__, num_msgs);
	for (i = 0; i < num_msgs; i++) {
		i2cmsg[i].addr = info->i2c_client->addr;
		i2cmsg[i].buf = (__u8 *)buf_start;

		if (i > 0)
			i2cmsg[i].flags = I2C_M_NOSTART;
		else
			i2cmsg[i].flags = 0;

		if (total_size > MAX_MSG_SIZE) {
			i2cmsg[i].len = MAX_MSG_SIZE;
			buf_start += MAX_MSG_SIZE;
			total_size -= MAX_MSG_SIZE;
		} else {
			i2cmsg[i].len = total_size;
		}
		dev_dbg(info->dev, "%s: addr:%x buf:%p, flags:%u len:%u\n",
			__func__, i2cmsg[i].addr, (void *)i2cmsg[i].buf,
			i2cmsg[i].flags, i2cmsg[i].len);
	}

	ret = i2c_transfer(info->i2c_client->adapter, i2cmsg, num_msgs);
	if (ret > 0)
		ret = 0;

	kfree(i2cmsg);
	mutex_unlock(&info->mutex);
	return ret;
}

static int isc_dev_raw_rw(struct isc_dev_info *info)
{
	struct isc_dev_package *pkg = &info->rw_pkg;
	void *u_ptr = (void *)pkg->buffer;
	u8 *buf;
	int ret = -ENODEV;

	dev_dbg(info->dev, "%s\n", __func__);

	buf = kzalloc(pkg->size, GFP_KERNEL);
	if (buf == NULL) {
		dev_err(info->dev, "%s: Unable to allocate memory!\n",
			__func__);
		return -ENOMEM;
	}
	if (pkg->flags & ISC_DEV_PKG_FLAG_WR) {
		/* write to device */
		if (copy_from_user(buf,
			(const void __user *)u_ptr, pkg->size)) {
			dev_err(info->dev, "%s copy_from_user err line %d\n",
				__func__, __LINE__);
			kfree(buf);
			return -EFAULT;
		}
		/* in the user access case, the offset is integrated in the
		 * buffer to be transferred, so pass -1 as the offset
		 */
		ret = isc_dev_raw_wr(info, -1, buf, pkg->size);
	} else {
		/* read from device */
		ret = isc_dev_raw_rd(info, pkg->offset,
				pkg->offset_len, buf, pkg->size);
		if (!ret && copy_to_user(
			(void __user *)u_ptr, buf, pkg->size)) {
			dev_err(info->dev, "%s copy_to_user err line %d\n",
				__func__, __LINE__);
			ret = -EINVAL;
		}
	}

	kfree(buf);
	return ret;
}

static int isc_dev_get_package(
	struct isc_dev_info *info, unsigned long arg)
{
	struct isc_dev_package pkg;

	if (copy_from_user(&pkg,
		(const void __user *)arg, sizeof(pkg))) {
		dev_err(info->dev, "%s copy_from_user err line %d\n",
			__func__, __LINE__);
		return -EFAULT;
	}
	info->rw_pkg.offset = pkg.offset;
	info->rw_pkg.offset_len = pkg.offset_len;
	info->rw_pkg.size = pkg.size;
	info->rw_pkg.flags = pkg.flags;
	info->rw_pkg.buffer = pkg.buffer;

	if ((void __user *)info->rw_pkg.buffer == NULL) {
		dev_err(info->dev, "%s package buffer NULL\n", __func__);
		return -EINVAL;
	}

	if (!info->rw_pkg.size) {
		dev_err(info->dev, "%s invalid package size %d\n",
			__func__, info->rw_pkg.size);
		return -EINVAL;
	}

	return 0;
}

static long isc_dev_ioctl(struct file *file,
			unsigned int cmd, unsigned long arg)
{
	struct isc_dev_info *info = file->private_data;
	int err = 0;

	switch (cmd) {
	case ISC_DEV_IOCTL_RW:
		err = isc_dev_get_package(info, arg);
		if (err)
			break;

		err = isc_dev_raw_rw(info);
		break;
	default:
		dev_dbg(info->dev, "%s: invalid cmd %x\n", __func__, cmd);
		return -EINVAL;
	}

	return err;
}

static int isc_dev_open(struct inode *inode, struct file *file)
{
	struct isc_dev_info *info;

	if (inode == NULL)
		return -ENODEV;

	info = container_of(inode->i_cdev, struct isc_dev_info, cdev);

	if (atomic_xchg(&info->in_use, 1))
		return -EBUSY;

	file->private_data = info;
	dev_dbg(info->dev, "%s\n", __func__);
	return 0;
}

static int isc_dev_release(struct inode *inode, struct file *file)
{
	struct isc_dev_info *info = file->private_data;

	dev_dbg(info->dev, "%s\n", __func__);
	file->private_data = NULL;
	WARN_ON(!atomic_xchg(&info->in_use, 0));
	return 0;
}

static const struct file_operations isc_dev_fileops = {
	.owner = THIS_MODULE,
	.open = isc_dev_open,
	.unlocked_ioctl = isc_dev_ioctl,
	.release = isc_dev_release,
};

#if defined(NV_I2C_DRIVER_STRUCT_PROBE_WITHOUT_I2C_DEVICE_ID_ARG) /* Linux 6.3 */
static int isc_dev_probe(struct i2c_client *client)
#else
static int isc_dev_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
#endif
{
	struct isc_dev_info *info;
	struct device *pdev;
	int err;

	dev_dbg(&client->dev, "%s: initializing link @%x-%04x\n",
		__func__, client->adapter->nr, client->addr);

	info = devm_kzalloc(
		&client->dev, sizeof(struct isc_dev_info), GFP_KERNEL);
	if (!info) {
		pr_err("%s: Unable to allocate memory!\n", __func__);
		return -ENOMEM;
	}

	mutex_init(&info->mutex);

	if (client->dev.platform_data) {
		info->pdata = client->dev.platform_data;
		dev_dbg(&client->dev, "pdata: %p\n", info->pdata);
	} else {
		dev_notice(&client->dev, "%s NO platform data\n", __func__);
		return -ENODEV;
	}

	if (info->pdata->reg_bits)
		info->reg_len = info->pdata->reg_bits / 8;
	else
		info->reg_len = 2;

	if (info->reg_len > 2) {
		dev_err(&client->dev,
			"device offset length invalid: %d\n", info->reg_len);
		devm_kfree(&client->dev, info);
		return -ENODEV;
	}
	info->i2c_client = client;
	info->dev = &client->dev;

	if (info->pdata)
		snprintf(info->devname, sizeof(info->devname),
			"%s", info->pdata->drv_name);
	else
		snprintf(info->devname, sizeof(info->devname),
			"isc-dev.%u.%02x", client->adapter->nr, client->addr);

	if (info->pdata->pdev == NULL)
		return -ENODEV;

	cdev_init(&info->cdev, &isc_dev_fileops);
	info->cdev.owner = THIS_MODULE;
	pdev = info->pdata->pdev;

	err = cdev_add(&info->cdev, MKDEV(MAJOR(pdev->devt), client->addr), 1);
	if (err < 0) {
		dev_err(&client->dev,
			"%s: Could not add cdev for %d\n", __func__,
			MKDEV(MAJOR(pdev->devt), client->addr));
		devm_kfree(&client->dev, info);
		return err;
	}

	/* send uevents to udev, it will create /dev node for isc-mgr */
	info->dev = device_create(pdev->class, &client->dev,
				  info->cdev.dev,
				  info, info->devname);
	if (IS_ERR(info->dev)) {
		info->dev = NULL;
		cdev_del(&info->cdev);
		devm_kfree(&client->dev, info);
		return PTR_ERR(info->dev);
	}

	info->power_is_on = 1;
	i2c_set_clientdata(client, info);
	isc_dev_debugfs_init(info);
	return 0;
}

#if KERNEL_VERSION(6, 1, 0) > LINUX_VERSION_CODE
static int isc_dev_remove(struct i2c_client *client)
#else
static void isc_dev_remove(struct i2c_client *client)
#endif
{
	struct isc_dev_info *info = i2c_get_clientdata(client);
	struct device *pdev;

	dev_dbg(&client->dev, "%s\n", __func__);
	isc_dev_debugfs_remove(info);

	/* remove only isc_dev_info not i2c_client itself */
	pdev = info->pdata->pdev;

	if (info->dev)
		device_destroy(pdev->class, info->cdev.dev);

	if (info->cdev.dev)
		cdev_del(&info->cdev);

#if KERNEL_VERSION(6, 1, 0) > LINUX_VERSION_CODE
	return 0;
#endif
}

#ifdef CONFIG_PM
static int isc_dev_suspend(struct device *dev)
{
	struct isc_dev_info *isc = (struct isc_dev_info *)dev_get_drvdata(dev);

	dev_info(dev, "Suspending\n");
	mutex_lock(&isc->mutex);
	isc->power_is_on = 0;
	mutex_unlock(&isc->mutex);

	return 0;
}

static int isc_dev_resume(struct device *dev)
{
	struct isc_dev_info *isc = (struct isc_dev_info *)dev_get_drvdata(dev);

	dev_info(dev, "Resuming\n");
	mutex_lock(&isc->mutex);
	isc->power_is_on = 1;
	mutex_unlock(&isc->mutex);

	return 0;
}
#endif

static const struct i2c_device_id isc_dev_id[] = {
	{ "isc-dev", 0 },
	{ },
};

static const struct dev_pm_ops isc_dev_pm_ops = {
	SET_RUNTIME_PM_OPS(isc_dev_suspend,
			isc_dev_resume, NULL)
	SET_SYSTEM_SLEEP_PM_OPS(isc_dev_suspend,
			isc_dev_resume)
};

static struct i2c_driver isc_dev_drv = {
	.driver = {
		.name = "isc-dev",
		.owner = THIS_MODULE,
		.pm = &isc_dev_pm_ops,
	},
	.id_table = isc_dev_id,
	.probe = isc_dev_probe,
	.remove = isc_dev_remove,
};

module_i2c_driver(isc_dev_drv);

MODULE_DESCRIPTION("ISC Generic I2C driver");
MODULE_AUTHOR("Charlie Huang <chahuang@nvidia.com>");
MODULE_LICENSE("GPL v2");
MODULE_SOFTDEP("pre: isc_gpio");