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c1b6b4f234
Let framebuffer drivers set their I2C bus class to DDC. Once this is done, we will be able to tell the eeprom driver to only probe for EDID EEPROMs on these buses. Signed-off-by: Jean Delvare <khali@linux-fr.org>
118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
/*
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* driver/vide/fb_ddc.c - DDC/EDID read support.
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*
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* Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com>
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*/
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/fb.h>
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#include <linux/i2c-algo-bit.h>
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#include "edid.h"
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#define DDC_ADDR 0x50
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static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter)
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{
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unsigned char start = 0x0;
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unsigned char *buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
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struct i2c_msg msgs[] = {
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{
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.addr = DDC_ADDR,
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.flags = 0,
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.len = 1,
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.buf = &start,
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}, {
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.addr = DDC_ADDR,
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.flags = I2C_M_RD,
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.len = EDID_LENGTH,
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.buf = buf,
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}
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};
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if (!buf) {
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dev_warn(&adapter->dev, "unable to allocate memory for EDID "
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"block.\n");
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return NULL;
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}
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if (i2c_transfer(adapter, msgs, 2) == 2)
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return buf;
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dev_warn(&adapter->dev, "unable to read EDID block.\n");
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kfree(buf);
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return NULL;
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}
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unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
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{
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struct i2c_algo_bit_data *algo_data = adapter->algo_data;
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unsigned char *edid = NULL;
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int i, j;
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algo_data->setscl(algo_data->data, 1);
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for (i = 0; i < 3; i++) {
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/* For some old monitors we need the
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* following process to initialize/stop DDC
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*/
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algo_data->setsda(algo_data->data, 1);
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msleep(13);
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algo_data->setscl(algo_data->data, 1);
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for (j = 0; j < 5; j++) {
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msleep(10);
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if (algo_data->getscl(algo_data->data))
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break;
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}
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if (j == 5)
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continue;
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algo_data->setsda(algo_data->data, 0);
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msleep(15);
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algo_data->setscl(algo_data->data, 0);
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msleep(15);
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algo_data->setsda(algo_data->data, 1);
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msleep(15);
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/* Do the real work */
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edid = fb_do_probe_ddc_edid(adapter);
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algo_data->setsda(algo_data->data, 0);
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algo_data->setscl(algo_data->data, 0);
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msleep(15);
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algo_data->setscl(algo_data->data, 1);
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for (j = 0; j < 10; j++) {
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msleep(10);
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if (algo_data->getscl(algo_data->data))
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break;
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}
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algo_data->setsda(algo_data->data, 1);
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msleep(15);
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algo_data->setscl(algo_data->data, 0);
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algo_data->setsda(algo_data->data, 0);
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if (edid)
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break;
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}
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/* Release the DDC lines when done or the Apple Cinema HD display
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* will switch off
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*/
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algo_data->setsda(algo_data->data, 1);
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algo_data->setscl(algo_data->data, 1);
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adapter->class |= I2C_CLASS_DDC;
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return edid;
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}
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EXPORT_SYMBOL_GPL(fb_ddc_read);
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MODULE_AUTHOR("Dennis Munsie <dmunsie@cecropia.com>");
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MODULE_DESCRIPTION("DDC/EDID reading support");
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MODULE_LICENSE("GPL");
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