| Dennis Munsie | fc5891c | 2006-10-03 01:14:42 -0700 | [diff] [blame] | 1 | /* |
| 2 | * driver/vide/fb_ddc.c - DDC/EDID read support. |
| 3 | * |
| 4 | * Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com> |
| 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> |
| 15 | |
| 16 | #include "edid.h" |
| 17 | |
| 18 | #define DDC_ADDR 0x50 |
| 19 | |
| 20 | static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter) |
| 21 | { |
| 22 | unsigned char start = 0x0; |
| 23 | struct i2c_msg msgs[] = { |
| 24 | { |
| 25 | .addr = DDC_ADDR, |
| 26 | .len = 1, |
| 27 | .buf = &start, |
| 28 | }, { |
| 29 | .addr = DDC_ADDR, |
| 30 | .flags = I2C_M_RD, |
| 31 | .len = EDID_LENGTH, |
| 32 | } |
| 33 | }; |
| 34 | unsigned char *buf; |
| 35 | |
| 36 | buf = kmalloc(EDID_LENGTH, GFP_KERNEL); |
| 37 | if (!buf) { |
| 38 | dev_warn(&adapter->dev, "unable to allocate memory for EDID " |
| 39 | "block.\n"); |
| 40 | return NULL; |
| 41 | } |
| 42 | msgs[1].buf = buf; |
| 43 | |
| 44 | if (i2c_transfer(adapter, msgs, 2) == 2) |
| 45 | return buf; |
| 46 | |
| 47 | dev_warn(&adapter->dev, "unable to read EDID block.\n"); |
| 48 | kfree(buf); |
| 49 | return NULL; |
| 50 | } |
| 51 | |
| 52 | unsigned char *fb_ddc_read(struct i2c_adapter *adapter) |
| 53 | { |
| 54 | struct i2c_algo_bit_data *algo_data = adapter->algo_data; |
| 55 | unsigned char *edid = NULL; |
| 56 | int i, j; |
| 57 | |
| 58 | algo_data->setscl(algo_data->data, 1); |
| 59 | algo_data->setscl(algo_data->data, 0); |
| 60 | |
| 61 | for (i = 0; i < 3; i++) { |
| 62 | /* For some old monitors we need the |
| 63 | * following process to initialize/stop DDC |
| 64 | */ |
| 65 | algo_data->setsda(algo_data->data, 0); |
| 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); |
| 100 | if (edid) |
| 101 | break; |
| 102 | } |
| 103 | /* Release the DDC lines when done or the Apple Cinema HD display |
| 104 | * will switch off |
| 105 | */ |
| 106 | algo_data->setsda(algo_data->data, 0); |
| 107 | algo_data->setscl(algo_data->data, 0); |
| 108 | |
| 109 | return edid; |
| 110 | } |
| 111 | |
| 112 | EXPORT_SYMBOL_GPL(fb_ddc_read); |
| 113 | |
| 114 | MODULE_AUTHOR("Dennis Munsie <dmunsie@cecropia.com>"); |
| 115 | MODULE_DESCRIPTION("DDC/EDID reading support"); |
| 116 | MODULE_LICENSE("GPL"); |