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

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