drivers/media/i2c/cs3308.c

Source file repositories/reference/linux-study-clean/drivers/media/i2c/cs3308.c

File Facts

System
Linux kernel
Corpus path
drivers/media/i2c/cs3308.c
Extension
.c
Size
3281 bytes
Lines
127
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Cirrus Logic cs3308 8-Channel Analog Volume Control
 *
 * Copyright (C) 2010 Devin Heitmueller <dheitmueller@kernellabs.com>
 * Copyright (C) 2012 Steven Toth <stoth@kernellabs.com>
 *
 * Derived from cs5345.c Copyright (C) 2007 Hans Verkuil
 */


#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>

MODULE_DESCRIPTION("i2c device driver for cs3308 8-channel volume control");
MODULE_AUTHOR("Devin Heitmueller");
MODULE_LICENSE("GPL");

static inline int cs3308_write(struct v4l2_subdev *sd, u8 reg, u8 value)
{
	struct i2c_client *client = v4l2_get_subdevdata(sd);

	return i2c_smbus_write_byte_data(client, reg, value);
}

static inline int cs3308_read(struct v4l2_subdev *sd, u8 reg)
{
	struct i2c_client *client = v4l2_get_subdevdata(sd);

	return i2c_smbus_read_byte_data(client, reg);
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int cs3308_g_register(struct v4l2_subdev *sd, struct v4l2_dbg_register *reg)
{
	reg->val = cs3308_read(sd, reg->reg & 0xffff);
	reg->size = 1;
	return 0;
}

static int cs3308_s_register(struct v4l2_subdev *sd, const struct v4l2_dbg_register *reg)
{
	cs3308_write(sd, reg->reg & 0xffff, reg->val & 0xff);
	return 0;
}
#endif

/* ----------------------------------------------------------------------- */

static const struct v4l2_subdev_core_ops cs3308_core_ops = {
#ifdef CONFIG_VIDEO_ADV_DEBUG
	.g_register = cs3308_g_register,
	.s_register = cs3308_s_register,
#endif
};

static const struct v4l2_subdev_ops cs3308_ops = {
	.core = &cs3308_core_ops,
};

/* ----------------------------------------------------------------------- */

static int cs3308_probe(struct i2c_client *client)
{
	struct v4l2_subdev *sd;
	unsigned i;

	/* Check if the adapter supports the needed features */
	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -EIO;

	if ((i2c_smbus_read_byte_data(client, 0x1c) & 0xf0) != 0xe0)
		return -ENODEV;

	v4l_info(client, "chip found @ 0x%x (%s)\n",
		 client->addr << 1, client->adapter->name);

	sd = kzalloc_obj(struct v4l2_subdev);
	if (sd == NULL)
		return -ENOMEM;

	v4l2_i2c_subdev_init(sd, client, &cs3308_ops);

	/* Set some reasonable defaults */
	cs3308_write(sd, 0x0d, 0x00); /* Power up all channels */
	cs3308_write(sd, 0x0e, 0x00); /* Master Power */

Annotation

Implementation Notes