drivers/gpu/drm/gma500/intel_i2c.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/gma500/intel_i2c.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/gma500/intel_i2c.c
Extension
.c
Size
3631 bytes
Lines
159
Domain
Driver Families
Bucket
drivers/gpu
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-only
/*
 * Copyright © 2006-2007 Intel Corporation
 *
 * Authors:
 *	Eric Anholt <eric@anholt.net>
 */

#include <linux/delay.h>
#include <linux/export.h>
#include <linux/i2c-algo-bit.h>
#include <linux/i2c.h>

#include "psb_drv.h"
#include "psb_intel_reg.h"

/*
 * Intel GPIO access functions
 */

#define I2C_RISEFALL_TIME 20

static int get_clock(void *data)
{
	struct gma_i2c_chan *chan = data;
	struct drm_device *dev = chan->drm_dev;
	u32 val;

	val = REG_READ(chan->reg);
	return (val & GPIO_CLOCK_VAL_IN) != 0;
}

static int get_data(void *data)
{
	struct gma_i2c_chan *chan = data;
	struct drm_device *dev = chan->drm_dev;
	u32 val;

	val = REG_READ(chan->reg);
	return (val & GPIO_DATA_VAL_IN) != 0;
}

static void set_clock(void *data, int state_high)
{
	struct gma_i2c_chan *chan = data;
	struct drm_device *dev = chan->drm_dev;
	u32 reserved = 0, clock_bits;

	/* On most chips, these bits must be preserved in software. */
	reserved =
		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
					   GPIO_CLOCK_PULLUP_DISABLE);

	if (state_high)
		clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
	else
		clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
		    GPIO_CLOCK_VAL_MASK;
	REG_WRITE(chan->reg, reserved | clock_bits);
	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
}

static void set_data(void *data, int state_high)
{
	struct gma_i2c_chan *chan = data;
	struct drm_device *dev = chan->drm_dev;
	u32 reserved = 0, data_bits;

	/* On most chips, these bits must be preserved in software. */
	reserved =
		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
					   GPIO_CLOCK_PULLUP_DISABLE);

	if (state_high)
		data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
	else
		data_bits =
		    GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
		    GPIO_DATA_VAL_MASK;

	REG_WRITE(chan->reg, reserved | data_bits);
	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
}

/**
 * gma_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
 * @dev: DRM device
 * @reg: GPIO reg to use
 * @name: name for this bus
 *

Annotation

Implementation Notes