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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /drivers/video/fbdev/core/fb_ddc.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/video/fbdev/core/fb_ddc.c')
-rw-r--r-- | drivers/video/fbdev/core/fb_ddc.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fb_ddc.c b/drivers/video/fbdev/core/fb_ddc.c new file mode 100644 index 000000000..8bf5f2f54 --- /dev/null +++ b/drivers/video/fbdev/core/fb_ddc.c @@ -0,0 +1,127 @@ +/* + * drivers/video/fb_ddc.c - DDC/EDID read support. + * + * Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com> + * + * 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); + if (algo_data->getscl) { + for (j = 0; j < 5; j++) { + msleep(10); + if (algo_data->getscl(algo_data->data)) + break; + } + if (j == 5) + continue; + } else { + udelay(algo_data->udelay); + } + + 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); + if (algo_data->getscl) { + for (j = 0; j < 10; j++) { + msleep(10); + if (algo_data->getscl(algo_data->data)) + break; + } + } else { + udelay(algo_data->udelay); + } + + 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 <dmunsie@cecropia.com>"); +MODULE_DESCRIPTION("DDC/EDID reading support"); +MODULE_LICENSE("GPL"); |