drivers/media/i2c/max9271.c

Source file repositories/reference/linux-study-clean/drivers/media/i2c/max9271.c

File Facts

System
Linux kernel
Corpus path
drivers/media/i2c/max9271.c
Extension
.c
Size
8226 bytes
Lines
375
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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+
/*
 * Copyright (C) 2017-2020 Jacopo Mondi
 * Copyright (C) 2017-2020 Kieran Bingham
 * Copyright (C) 2017-2020 Laurent Pinchart
 * Copyright (C) 2017-2020 Niklas Söderlund
 * Copyright (C) 2016 Renesas Electronics Corporation
 * Copyright (C) 2015 Cogent Embedded, Inc.
 *
 * This file exports functions to control the Maxim MAX9271 GMSL serializer
 * chip. This is not a self-contained driver, as MAX9271 is usually embedded in
 * camera modules with at least one image sensor and optional additional
 * components, such as uController units or ISPs/DSPs.
 *
 * Drivers for the camera modules (i.e. rdacm20/21) are expected to use
 * functions exported from this library driver to maximize code re-use.
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>

#include "max9271.h"

static int max9271_read(struct max9271_device *dev, u8 reg)
{
	int ret;

	dev_dbg(&dev->client->dev, "%s(0x%02x)\n", __func__, reg);

	ret = i2c_smbus_read_byte_data(dev->client, reg);
	if (ret < 0)
		dev_dbg(&dev->client->dev,
			"%s: register 0x%02x read failed (%d)\n",
			__func__, reg, ret);

	return ret;
}

static int max9271_write(struct max9271_device *dev, u8 reg, u8 val)
{
	int ret;

	dev_dbg(&dev->client->dev, "%s(0x%02x, 0x%02x)\n", __func__, reg, val);

	ret = i2c_smbus_write_byte_data(dev->client, reg, val);
	if (ret < 0)
		dev_err(&dev->client->dev,
			"%s: register 0x%02x write failed (%d)\n",
			__func__, reg, ret);

	return ret;
}

/*
 * max9271_pclk_detect() - Detect valid pixel clock from image sensor
 *
 * Wait up to 10ms for a valid pixel clock.
 *
 * Returns 0 for success, < 0 for pixel clock not properly detected
 */
static int max9271_pclk_detect(struct max9271_device *dev)
{
	unsigned int i;
	int ret;

	for (i = 0; i < 100; i++) {
		ret = max9271_read(dev, 0x15);
		if (ret < 0)
			return ret;

		if (ret & MAX9271_PCLKDET)
			return 0;

		usleep_range(50, 100);
	}

	dev_err(&dev->client->dev, "Unable to detect valid pixel clock\n");

	return -EIO;
}

void max9271_wake_up(struct max9271_device *dev)
{
	/*
	 * Use the chip default address as this function has to be called
	 * before any other one.
	 */
	dev->client->addr = MAX9271_DEFAULT_ADDR;
	i2c_smbus_read_byte(dev->client);

Annotation

Implementation Notes