[linux.git] / drivers / video / fb_ddc.c

/*
 * drivers/video/fb_ddc.c - DDC/EDID read support.
 *
 *  Copyright (C) 2006 Dennis Munsie <[email protected]>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/fb.h>
#include <linux/i2c-algo-bit.h>
#include <linux/slab.h>

#include "edid.h"

#define DDC_ADDR	0x50

static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter)
{
	unsigned char start = 0x0;
	unsigned char *buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
	struct i2c_msg msgs[] = {
		{
			.addr	= DDC_ADDR,
			.flags	= 0,
			.len	= 1,
			.buf	= &start,
		}, {
			.addr	= DDC_ADDR,
			.flags	= I2C_M_RD,
			.len	= EDID_LENGTH,
			.buf	= buf,
		}
	};

	if (!buf) {
		dev_warn(&adapter->dev, "unable to allocate memory for EDID "
			 "block.\n");
		return NULL;
	}

	if (i2c_transfer(adapter, msgs, 2) == 2)
		return buf;

	dev_warn(&adapter->dev, "unable to read EDID block.\n");
	kfree(buf);
	return NULL;
}

unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
{
	struct i2c_algo_bit_data *algo_data = adapter->algo_data;
	unsigned char *edid = NULL;
	int i, j;

	algo_data->setscl(algo_data->data, 1);

	for (i = 0; i < 3; i++) {
		/* For some old monitors we need the
		 * following process to initialize/stop DDC
		 */
		algo_data->setsda(algo_data->data, 1);
		msleep(13);

		algo_data->setscl(algo_data->data, 1);
		for (j = 0; j < 5; j++) {
			msleep(10);
			if (algo_data->getscl(algo_data->data))
				break;
		}
		if (j == 5)
			continue;

		algo_data->setsda(algo_data->data, 0);
		msleep(15);
		algo_data->setscl(algo_data->data, 0);
		msleep(15);
		algo_data->setsda(algo_data->data, 1);
		msleep(15);

		/* Do the real work */
		edid = fb_do_probe_ddc_edid(adapter);
		algo_data->setsda(algo_data->data, 0);
		algo_data->setscl(algo_data->data, 0);
		msleep(15);

		algo_data->setscl(algo_data->data, 1);
		for (j = 0; j < 10; j++) {
			msleep(10);
			if (algo_data->getscl(algo_data->data))
				break;
		}

		algo_data->setsda(algo_data->data, 1);
		msleep(15);
		algo_data->setscl(algo_data->data, 0);
		algo_data->setsda(algo_data->data, 0);
		if (edid)
			break;
	}
	/* Release the DDC lines when done or the Apple Cinema HD display
	 * will switch off
	 */
	algo_data->setsda(algo_data->data, 1);
	algo_data->setscl(algo_data->data, 1);

	adapter->class |= I2C_CLASS_DDC;
	return edid;
}

EXPORT_SYMBOL_GPL(fb_ddc_read);

MODULE_AUTHOR("Dennis Munsie <[email protected]>");
MODULE_DESCRIPTION("DDC/EDID reading support");
MODULE_LICENSE("GPL");
Commit	Line	Data
fc5891c8	1	/*
355b200b	2	* drivers/video/fb_ddc.c - DDC/EDID read support.
fc5891c8 DM	3	*
	4	* Copyright (C) 2006 Dennis Munsie <[email protected]>
	5	*
	6	* This file is subject to the terms and conditions of the GNU General Public
	7	* License. See the file COPYING in the main directory of this archive
	8	* for more details.
	9	*/
	10
	11	#include <linux/delay.h>
	12	#include <linux/device.h>
355b200b	13	#include <linux/module.h>
fc5891c8 DM	14	#include <linux/fb.h>
fc5891c8 DM	15	#include <linux/i2c-algo-bit.h>
5a0e3ad6	16	#include <linux/slab.h>
fc5891c8 DM	17
	18	#include "edid.h"
	19
	20	#define DDC_ADDR 0x50
	21
	22	static unsigned char fb_do_probe_ddc_edid(struct i2c_adapter adapter)
	23	{
	24	unsigned char start = 0x0;
4be70390	25	unsigned char *buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
fc5891c8 DM	26	struct i2c_msg msgs[] = {
	27	{
	28	.addr = DDC_ADDR,
4be70390	29	.flags = 0,
fc5891c8 DM	30	.len = 1,
	31	.buf = &start,
	32	}, {
	33	.addr = DDC_ADDR,
	34	.flags = I2C_M_RD,
	35	.len = EDID_LENGTH,
4be70390	36	.buf = buf,
fc5891c8 DM	37	}
fc5891c8 DM	38	};
fc5891c8	39
fc5891c8 DM	40	if (!buf) {
	41	dev_warn(&adapter->dev, "unable to allocate memory for EDID "
	42	"block.\n");
	43	return NULL;
	44	}
fc5891c8 DM	45
	46	if (i2c_transfer(adapter, msgs, 2) == 2)
	47	return buf;
	48
	49	dev_warn(&adapter->dev, "unable to read EDID block.\n");
	50	kfree(buf);
	51	return NULL;
	52	}
	53
	54	unsigned char fb_ddc_read(struct i2c_adapter adapter)
	55	{
	56	struct i2c_algo_bit_data *algo_data = adapter->algo_data;
	57	unsigned char *edid = NULL;
	58	int i, j;
	59
	60	algo_data->setscl(algo_data->data, 1);
fc5891c8 DM	61
	62	for (i = 0; i < 3; i++) {
	63	/* For some old monitors we need the
	64	* following process to initialize/stop DDC
	65	*/
b64d7082	66	algo_data->setsda(algo_data->data, 1);
fc5891c8 DM	67	msleep(13);
	68
	69	algo_data->setscl(algo_data->data, 1);
	70	for (j = 0; j < 5; j++) {
	71	msleep(10);
	72	if (algo_data->getscl(algo_data->data))
	73	break;
	74	}
	75	if (j == 5)
	76	continue;
	77
	78	algo_data->setsda(algo_data->data, 0);
	79	msleep(15);
	80	algo_data->setscl(algo_data->data, 0);
	81	msleep(15);
	82	algo_data->setsda(algo_data->data, 1);
	83	msleep(15);
	84
	85	/* Do the real work */
	86	edid = fb_do_probe_ddc_edid(adapter);
	87	algo_data->setsda(algo_data->data, 0);
	88	algo_data->setscl(algo_data->data, 0);
	89	msleep(15);
	90
	91	algo_data->setscl(algo_data->data, 1);
	92	for (j = 0; j < 10; j++) {
	93	msleep(10);
	94	if (algo_data->getscl(algo_data->data))
	95	break;
	96	}
	97
	98	algo_data->setsda(algo_data->data, 1);
	99	msleep(15);
	100	algo_data->setscl(algo_data->data, 0);
b64d7082	101	algo_data->setsda(algo_data->data, 0);
fc5891c8 DM	102	if (edid)
	103	break;
	104	}
	105	/* Release the DDC lines when done or the Apple Cinema HD display
	106	* will switch off
	107	*/
b64d7082 JD	108	algo_data->setsda(algo_data->data, 1);
b64d7082 JD	109	algo_data->setscl(algo_data->data, 1);
fc5891c8	110
c1b6b4f2	111	adapter->class \|= I2C_CLASS_DDC;
fc5891c8 DM	112	return edid;
	113	}
	114
	115	EXPORT_SYMBOL_GPL(fb_ddc_read);
	116
	117	MODULE_AUTHOR("Dennis Munsie <[email protected]>");
	118	MODULE_DESCRIPTION("DDC/EDID reading support");
	119	MODULE_LICENSE("GPL");