MIPS: handle write_combine in pci_mmap_page_range

[linux-2.6/linux-loongson.git] / drivers / gpu / drm / drm_edid.c

/*
 * Copyright (c) 2006 Luc Verhaegen (quirks list)
 * Copyright (c) 2007-2008 Intel Corporation
 *   Jesse Barnes <jesse.barnes@intel.com>
 *
 * DDC probing routines (drm_ddc_read & drm_do_probe_ddc_edid) originally from
 * FB layer.
 *   Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include "drmP.h"
#include "drm_edid.h"

/*
 * TODO:
 *   - support EDID 1.4 (incl. CE blocks)
 */

/*
 * EDID blocks out in the wild have a variety of bugs, try to collect
 * them here (note that userspace may work around broken monitors first,
 * but fixes should make their way here so that the kernel "just works"
 * on as many displays as possible).
 */

/* First detailed mode wrong, use largest 60Hz mode */
#define EDID_QUIRK_PREFER_LARGE_60              (1 << 0)
/* Reported 135MHz pixel clock is too high, needs adjustment */
#define EDID_QUIRK_135_CLOCK_TOO_HIGH           (1 << 1)
/* Prefer the largest mode at 75 Hz */
#define EDID_QUIRK_PREFER_LARGE_75              (1 << 2)
/* Detail timing is in cm not mm */
#define EDID_QUIRK_DETAILED_IN_CM               (1 << 3)
/* Detailed timing descriptors have bogus size values, so just take the
 * maximum size and use that.
 */
#define EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE    (1 << 4)
/* Monitor forgot to set the first detailed is preferred bit. */
#define EDID_QUIRK_FIRST_DETAILED_PREFERRED     (1 << 5)
/* use +hsync +vsync for detailed mode */
#define EDID_QUIRK_DETAILED_SYNC_PP             (1 << 6)

static struct edid_quirk {
        char *vendor;
        int product_id;
        u32 quirks;
} edid_quirk_list[] = {
        /* Acer AL1706 */
        { "ACR", 44358, EDID_QUIRK_PREFER_LARGE_60 },
        /* Acer F51 */
        { "API", 0x7602, EDID_QUIRK_PREFER_LARGE_60 },
        /* Unknown Acer */
        { "ACR", 2423, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Belinea 10 15 55 */
        { "MAX", 1516, EDID_QUIRK_PREFER_LARGE_60 },
        { "MAX", 0x77e, EDID_QUIRK_PREFER_LARGE_60 },

        /* Envision Peripherals, Inc. EN-7100e */
        { "EPI", 59264, EDID_QUIRK_135_CLOCK_TOO_HIGH },

        /* Funai Electronics PM36B */
        { "FCM", 13600, EDID_QUIRK_PREFER_LARGE_75 |
          EDID_QUIRK_DETAILED_IN_CM },

        /* LG Philips LCD LP154W01-A5 */
        { "LPL", 0, EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE },
        { "LPL", 0x2a00, EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE },

        /* Philips 107p5 CRT */
        { "PHL", 57364, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Proview AY765C */
        { "PTS", 765, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Samsung SyncMaster 205BW.  Note: irony */
        { "SAM", 541, EDID_QUIRK_DETAILED_SYNC_PP },
        /* Samsung SyncMaster 22[5-6]BW */
        { "SAM", 596, EDID_QUIRK_PREFER_LARGE_60 },
        { "SAM", 638, EDID_QUIRK_PREFER_LARGE_60 },
};


/* Valid EDID header has these bytes */
static u8 edid_header[] = { 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00 };

/**
 * edid_is_valid - sanity check EDID data
 * @edid: EDID data
 *
 * Sanity check the EDID block by looking at the header, the version number
 * and the checksum.  Return 0 if the EDID doesn't check out, or 1 if it's
 * valid.
 */
static bool edid_is_valid(struct edid *edid)
{
        int i;
        u8 csum = 0;
        u8 *raw_edid = (u8 *)edid;

        if (memcmp(edid->header, edid_header, sizeof(edid_header)))
                goto bad;
        if (edid->version != 1) {
                DRM_ERROR("EDID has major version %d, instead of 1\n", edid->version);
                goto bad;
        }
        if (edid->revision > 4)
                DRM_DEBUG("EDID minor > 4, assuming backward compatibility\n");

        for (i = 0; i < EDID_LENGTH; i++)
                csum += raw_edid[i];
        if (csum) {
                DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum);
                goto bad;
        }

        return 1;

bad:
        if (raw_edid) {
                DRM_ERROR("Raw EDID:\n");
                print_hex_dump_bytes(KERN_ERR, DUMP_PREFIX_NONE, raw_edid, EDID_LENGTH);
                printk("\n");
        }
        return 0;
}

/**
 * edid_vendor - match a string against EDID's obfuscated vendor field
 * @edid: EDID to match
 * @vendor: vendor string
 *
 * Returns true if @vendor is in @edid, false otherwise
 */
static bool edid_vendor(struct edid *edid, char *vendor)
{
        char edid_vendor[3];

        edid_vendor[0] = ((edid->mfg_id[0] & 0x7c) >> 2) + '@';
        edid_vendor[1] = (((edid->mfg_id[0] & 0x3) << 3) |
                          ((edid->mfg_id[1] & 0xe0) >> 5)) + '@';
        edid_vendor[2] = (edid->mfg_id[1] & 0x1f) + '@';

        return !strncmp(edid_vendor, vendor, 3);
}

/**
 * edid_get_quirks - return quirk flags for a given EDID
 * @edid: EDID to process
 *
 * This tells subsequent routines what fixes they need to apply.
 */
static u32 edid_get_quirks(struct edid *edid)
{
        struct edid_quirk *quirk;
        int i;

        for (i = 0; i < ARRAY_SIZE(edid_quirk_list); i++) {
                quirk = &edid_quirk_list[i];

                if (edid_vendor(edid, quirk->vendor) &&
                    (EDID_PRODUCT_ID(edid) == quirk->product_id))
                        return quirk->quirks;
        }

        return 0;
}

#define MODE_SIZE(m) ((m)->hdisplay * (m)->vdisplay)
#define MODE_REFRESH_DIFF(m,r) (abs((m)->vrefresh - target_refresh))


/**
 * edid_fixup_preferred - set preferred modes based on quirk list
 * @connector: has mode list to fix up
 * @quirks: quirks list
 *
 * Walk the mode list for @connector, clearing the preferred status
 * on existing modes and setting it anew for the right mode ala @quirks.
 */
static void edid_fixup_preferred(struct drm_connector *connector,
                                 u32 quirks)
{
        struct drm_display_mode *t, *cur_mode, *preferred_mode;
        int target_refresh = 0;

        if (list_empty(&connector->probed_modes))
                return;

        if (quirks & EDID_QUIRK_PREFER_LARGE_60)
                target_refresh = 60;
        if (quirks & EDID_QUIRK_PREFER_LARGE_75)
                target_refresh = 75;

        preferred_mode = list_first_entry(&connector->probed_modes,
                                          struct drm_display_mode, head);

        list_for_each_entry_safe(cur_mode, t, &connector->probed_modes, head) {
                cur_mode->type &= ~DRM_MODE_TYPE_PREFERRED;

                if (cur_mode == preferred_mode)
                        continue;

                /* Largest mode is preferred */
                if (MODE_SIZE(cur_mode) > MODE_SIZE(preferred_mode))
                        preferred_mode = cur_mode;

                /* At a given size, try to get closest to target refresh */
                if ((MODE_SIZE(cur_mode) == MODE_SIZE(preferred_mode)) &&
                    MODE_REFRESH_DIFF(cur_mode, target_refresh) <
                    MODE_REFRESH_DIFF(preferred_mode, target_refresh)) {
                        preferred_mode = cur_mode;
                }
        }

        preferred_mode->type |= DRM_MODE_TYPE_PREFERRED;
}

/**
 * drm_mode_std - convert standard mode info (width, height, refresh) into mode
 * @t: standard timing params
 *
 * Take the standard timing params (in this case width, aspect, and refresh)
 * and convert them into a real mode using CVT.
 *
 * Punts for now, but should eventually use the FB layer's CVT based mode
 * generation code.
 */
struct drm_display_mode *drm_mode_std(struct drm_device *dev,
                                      struct std_timing *t)
{
        struct drm_display_mode *mode;
        int hsize = t->hsize * 8 + 248, vsize;

        mode = drm_mode_create(dev);
        if (!mode)
                return NULL;

        if (t->aspect_ratio == 0)
                vsize = (hsize * 10) / 16;
        else if (t->aspect_ratio == 1)
                vsize = (hsize * 3) / 4;
        else if (t->aspect_ratio == 2)
                vsize = (hsize * 4) / 5;
        else
                vsize = (hsize * 9) / 16;

        drm_mode_set_name(mode);

        return mode;
}

/**
 * drm_mode_detailed - create a new mode from an EDID detailed timing section
 * @dev: DRM device (needed to create new mode)
 * @edid: EDID block
 * @timing: EDID detailed timing info
 * @quirks: quirks to apply
 *
 * An EDID detailed timing block contains enough info for us to create and
 * return a new struct drm_display_mode.
 */
static struct drm_display_mode *drm_mode_detailed(struct drm_device *dev,
                                                  struct edid *edid,
                                                  struct detailed_timing *timing,
                                                  u32 quirks)
{
        struct drm_display_mode *mode;
        struct detailed_pixel_timing *pt = &timing->data.pixel_data;

        if (pt->stereo) {
                printk(KERN_WARNING "stereo mode not supported\n");
                return NULL;
        }
        if (!pt->separate_sync) {
                printk(KERN_WARNING "integrated sync not supported\n");
                return NULL;
        }

        mode = drm_mode_create(dev);
        if (!mode)
                return NULL;

        mode->type = DRM_MODE_TYPE_DRIVER;

        if (quirks & EDID_QUIRK_135_CLOCK_TOO_HIGH)
                timing->pixel_clock = 1088;

        mode->clock = timing->pixel_clock * 10;

        mode->hdisplay = (pt->hactive_hi << 8) | pt->hactive_lo;
        mode->hsync_start = mode->hdisplay + ((pt->hsync_offset_hi << 8) |
                                              pt->hsync_offset_lo);
        mode->hsync_end = mode->hsync_start +
                ((pt->hsync_pulse_width_hi << 8) |
                 pt->hsync_pulse_width_lo);
        mode->htotal = mode->hdisplay + ((pt->hblank_hi << 8) | pt->hblank_lo);

        mode->vdisplay = (pt->vactive_hi << 8) | pt->vactive_lo;
        mode->vsync_start = mode->vdisplay + ((pt->vsync_offset_hi << 4) |
                                              pt->vsync_offset_lo);
        mode->vsync_end = mode->vsync_start +
                ((pt->vsync_pulse_width_hi << 4) |
                 pt->vsync_pulse_width_lo);
        mode->vtotal = mode->vdisplay + ((pt->vblank_hi << 8) | pt->vblank_lo);

        drm_mode_set_name(mode);

        if (pt->interlaced)
                mode->flags |= DRM_MODE_FLAG_INTERLACE;

        if (quirks & EDID_QUIRK_DETAILED_SYNC_PP) {
                pt->hsync_positive = 1;
                pt->vsync_positive = 1;
        }

        mode->flags |= pt->hsync_positive ? DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC;
        mode->flags |= pt->vsync_positive ? DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC;

        mode->width_mm = pt->width_mm_lo | (pt->width_mm_hi << 8);
        mode->height_mm = pt->height_mm_lo | (pt->height_mm_hi << 8);

        if (quirks & EDID_QUIRK_DETAILED_IN_CM) {
                mode->width_mm *= 10;
                mode->height_mm *= 10;
        }

        if (quirks & EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE) {
                mode->width_mm = edid->width_cm * 10;
                mode->height_mm = edid->height_cm * 10;
        }

        return mode;
}

/*
 * Detailed mode info for the EDID "established modes" data to use.
 */
static struct drm_display_mode edid_est_modes[] = {
        { DRM_MODE("800x600", DRM_MODE_TYPE_DRIVER, 40000, 800, 840,
                   968, 1056, 0, 600, 601, 605, 628, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 800x600@60Hz */
        { DRM_MODE("800x600", DRM_MODE_TYPE_DRIVER, 36000, 800, 824,
                   896, 1024, 0, 600, 601, 603,  625, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 800x600@56Hz */
        { DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 31500, 640, 656,
                   720, 840, 0, 480, 481, 484, 500, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 640x480@75Hz */
        { DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 31500, 640, 664,
                   704,  832, 0, 480, 489, 491, 520, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 640x480@72Hz */
        { DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 30240, 640, 704,
                   768,  864, 0, 480, 483, 486, 525, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 640x480@67Hz */
        { DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 25200, 640, 656,
                   752, 800, 0, 480, 490, 492, 525, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 640x480@60Hz */
        { DRM_MODE("720x400", DRM_MODE_TYPE_DRIVER, 35500, 720, 738,
                   846, 900, 0, 400, 421, 423,  449, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 720x400@88Hz */
        { DRM_MODE("720x400", DRM_MODE_TYPE_DRIVER, 28320, 720, 738,
                   846,  900, 0, 400, 412, 414, 449, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 720x400@70Hz */
        { DRM_MODE("1280x1024", DRM_MODE_TYPE_DRIVER, 135000, 1280, 1296,
                   1440, 1688, 0, 1024, 1025, 1028, 1066, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 1280x1024@75Hz */
        { DRM_MODE("1024x768", DRM_MODE_TYPE_DRIVER, 78800, 1024, 1040,
                   1136, 1312, 0,  768, 769, 772, 800, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 1024x768@75Hz */
        { DRM_MODE("1024x768", DRM_MODE_TYPE_DRIVER, 75000, 1024, 1048,
                   1184, 1328, 0,  768, 771, 777, 806, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 1024x768@70Hz */
        { DRM_MODE("1024x768", DRM_MODE_TYPE_DRIVER, 65000, 1024, 1048,
                   1184, 1344, 0,  768, 771, 777, 806, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 1024x768@60Hz */
        { DRM_MODE("1024x768", DRM_MODE_TYPE_DRIVER,44900, 1024, 1032,
                   1208, 1264, 0, 768, 768, 776, 817, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_INTERLACE) }, /* 1024x768@43Hz */
        { DRM_MODE("832x624", DRM_MODE_TYPE_DRIVER, 57284, 832, 864,
                   928, 1152, 0, 624, 625, 628, 667, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, /* 832x624@75Hz */
        { DRM_MODE("800x600", DRM_MODE_TYPE_DRIVER, 49500, 800, 816,
                   896, 1056, 0, 600, 601, 604,  625, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 800x600@75Hz */
        { DRM_MODE("800x600", DRM_MODE_TYPE_DRIVER, 50000, 800, 856,
                   976, 1040, 0, 600, 637, 643, 666, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 800x600@72Hz */
        { DRM_MODE("1152x864", DRM_MODE_TYPE_DRIVER, 108000, 1152, 1216,
                   1344, 1600, 0,  864, 865, 868, 900, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) }, /* 1152x864@75Hz */
};

#define EDID_EST_TIMINGS 16
#define EDID_STD_TIMINGS 8
#define EDID_DETAILED_TIMINGS 4

/**
 * add_established_modes - get est. modes from EDID and add them
 * @edid: EDID block to scan
 *
 * Each EDID block contains a bitmap of the supported "established modes" list
 * (defined above).  Tease them out and add them to the global modes list.
 */
static int add_established_modes(struct drm_connector *connector, struct edid *edid)
{
        struct drm_device *dev = connector->dev;
        unsigned long est_bits = edid->established_timings.t1 |
                (edid->established_timings.t2 << 8) |
                ((edid->established_timings.mfg_rsvd & 0x80) << 9);
        int i, modes = 0;

        for (i = 0; i <= EDID_EST_TIMINGS; i++)
                if (est_bits & (1<<i)) {
                        struct drm_display_mode *newmode;
                        newmode = drm_mode_duplicate(dev, &edid_est_modes[i]);
                        if (newmode) {
                                drm_mode_probed_add(connector, newmode);
                                modes++;
                        }
                }

        return modes;
}

/**
 * add_standard_modes - get std. modes from EDID and add them
 * @edid: EDID block to scan
 *
 * Standard modes can be calculated using the CVT standard.  Grab them from
 * @edid, calculate them, and add them to the list.
 */
static int add_standard_modes(struct drm_connector *connector, struct edid *edid)
{
        struct drm_device *dev = connector->dev;
        int i, modes = 0;

        for (i = 0; i < EDID_STD_TIMINGS; i++) {
                struct std_timing *t = &edid->standard_timings[i];
                struct drm_display_mode *newmode;

                /* If std timings bytes are 1, 1 it's empty */
                if (t->hsize == 1 && (t->aspect_ratio | t->vfreq) == 1)
                        continue;

                newmode = drm_mode_std(dev, &edid->standard_timings[i]);
                if (newmode) {
                        drm_mode_probed_add(connector, newmode);
                        modes++;
                }
        }

        return modes;
}

/**
 * add_detailed_modes - get detailed mode info from EDID data
 * @connector: attached connector
 * @edid: EDID block to scan
 * @quirks: quirks to apply
 *
 * Some of the detailed timing sections may contain mode information.  Grab
 * it and add it to the list.
 */
static int add_detailed_info(struct drm_connector *connector,
                             struct edid *edid, u32 quirks)
{
        struct drm_device *dev = connector->dev;
        int i, j, modes = 0;

        for (i = 0; i < EDID_DETAILED_TIMINGS; i++) {
                struct detailed_timing *timing = &edid->detailed_timings[i];
                struct detailed_non_pixel *data = &timing->data.other_data;
                struct drm_display_mode *newmode;

                /* EDID up to and including 1.2 may put monitor info here */
                if (edid->version == 1 && edid->revision < 3)
                        continue;

                /* Detailed mode timing */
                if (timing->pixel_clock) {
                        newmode = drm_mode_detailed(dev, edid, timing, quirks);
                        if (!newmode)
                                continue;

                        /* First detailed mode is preferred */
                        if (i == 0 && edid->preferred_timing)
                                newmode->type |= DRM_MODE_TYPE_PREFERRED;
                        drm_mode_probed_add(connector, newmode);

                        modes++;
                        continue;
                }

                /* Other timing or info */
                switch (data->type) {
                case EDID_DETAIL_MONITOR_SERIAL:
                        break;
                case EDID_DETAIL_MONITOR_STRING:
                        break;
                case EDID_DETAIL_MONITOR_RANGE:
                        /* Get monitor range data */
                        break;
                case EDID_DETAIL_MONITOR_NAME:
                        break;
                case EDID_DETAIL_MONITOR_CPDATA:
                        break;
                case EDID_DETAIL_STD_MODES:
                        /* Five modes per detailed section */
                        for (j = 0; j < 5; i++) {
                                struct std_timing *std;
                                struct drm_display_mode *newmode;

                                std = &data->data.timings[j];
                                newmode = drm_mode_std(dev, std);
                                if (newmode) {
                                        drm_mode_probed_add(connector, newmode);
                                        modes++;
                                }
                        }
                        break;
                default:
                        break;
                }
        }

        return modes;
}

#define DDC_ADDR 0x50
/**
 * Get EDID information via I2C.
 *
 * \param adapter : i2c device adaptor
 * \param buf     : EDID data buffer to be filled
 * \param len     : EDID data buffer length
 * \return 0 on success or -1 on failure.
 *
 * Try to fetch EDID information by calling i2c driver function.
 */
int drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
                          unsigned char *buf, int len)
{
        unsigned char start = 0x0;
        struct i2c_msg msgs[] = {
                {
                        .addr   = DDC_ADDR,
                        .flags  = 0,
                        .len    = 1,
                        .buf    = &start,
                }, {
                        .addr   = DDC_ADDR,
                        .flags  = I2C_M_RD,
                        .len    = len,
                        .buf    = buf,
                }
        };

        if (i2c_transfer(adapter, msgs, 2) == 2)
                return 0;

        dev_info(&adapter->dev, "unable to read EDID block.\n");
        return -1;
}
EXPORT_SYMBOL(drm_do_probe_ddc_edid);

/**
 * Get EDID information.
 *
 * \param adapter : i2c device adaptor.
 * \param buf     : EDID data buffer to be filled
 * \param len     : EDID data buffer length
 * \return 0 on success or -1 on failure.
 *
 * Initialize DDC, then fetch EDID information
 * by calling drm_do_probe_ddc_edid function.
 */
static int drm_ddc_read(struct i2c_adapter *adapter,
                        unsigned char *buf, int len)
{
        struct i2c_algo_bit_data *algo_data = adapter->algo_data;
        int i, j;
        int ret = -1;

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

        for (i = 0; i < 1; 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 */
                ret = drm_do_probe_ddc_edid(adapter, buf, len);
                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 (ret == 0)
                        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);

        return ret;
}

static int drm_ddc_read_edid(struct drm_connector *connector,
                             struct i2c_adapter *adapter,
                             char *buf, int len)
{
        int ret;

        ret = drm_ddc_read(adapter, buf, len);
        if (ret != 0) {
                dev_info(&connector->dev->pdev->dev, "%s: no EDID data\n",
                         drm_get_connector_name(connector));
                goto end;
        }
        if (!edid_is_valid((struct edid *)buf)) {
                dev_warn(&connector->dev->pdev->dev, "%s: EDID invalid.\n",
                         drm_get_connector_name(connector));
                ret = -1;
        }
end:
        return ret;
}

#define MAX_EDID_EXT_NUM 4
/**
 * drm_get_edid - get EDID data, if available
 * @connector: connector we're probing
 * @adapter: i2c adapter to use for DDC
 *
 * Poke the given connector's i2c channel to grab EDID data if possible.
 *
 * Return edid data or NULL if we couldn't find any.
 */
struct edid *drm_get_edid(struct drm_connector *connector,
                          struct i2c_adapter *adapter)
{
        int ret;
        struct edid *edid;

        edid = kmalloc(EDID_LENGTH * (MAX_EDID_EXT_NUM + 1),
                       GFP_KERNEL);
        if (edid == NULL) {
                dev_warn(&connector->dev->pdev->dev,
                         "Failed to allocate EDID\n");
                goto end;
        }

        /* Read first EDID block */
        ret = drm_ddc_read_edid(connector, adapter,
                                (unsigned char *)edid, EDID_LENGTH);
        if (ret != 0)
                goto clean_up;

        /* There are EDID extensions to be read */
        if (edid->extensions != 0) {
                int edid_ext_num = edid->extensions;

                if (edid_ext_num > MAX_EDID_EXT_NUM) {
                        dev_warn(&connector->dev->pdev->dev,
                                 "The number of extension(%d) is "
                                 "over max (%d), actually read number (%d)\n",
                                 edid_ext_num, MAX_EDID_EXT_NUM,
                                 MAX_EDID_EXT_NUM);
                        /* Reset EDID extension number to be read */
                        edid_ext_num = MAX_EDID_EXT_NUM;
                }
                /* Read EDID including extensions too */
                ret = drm_ddc_read_edid(connector, adapter, (char *)edid,
                                        EDID_LENGTH * (edid_ext_num + 1));
                if (ret != 0)
                        goto clean_up;

        }

        connector->display_info.raw_edid = (char *)edid;
        goto end;

clean_up:
        kfree(edid);
        edid = NULL;
end:
        return edid;

}
EXPORT_SYMBOL(drm_get_edid);

#define HDMI_IDENTIFIER 0x000C03
#define VENDOR_BLOCK    0x03
/**
 * drm_detect_hdmi_monitor - detect whether monitor is hdmi.
 * @edid: monitor EDID information
 *
 * Parse the CEA extension according to CEA-861-B.
 * Return true if HDMI, false if not or unknown.
 */
bool drm_detect_hdmi_monitor(struct edid *edid)
{
        char *edid_ext = NULL;
        int i, hdmi_id, edid_ext_num;
        int start_offset, end_offset;
        bool is_hdmi = false;

        /* No EDID or EDID extensions */
        if (edid == NULL || edid->extensions == 0)
                goto end;

        /* Chose real EDID extension number */
        edid_ext_num = edid->extensions > MAX_EDID_EXT_NUM ?
                       MAX_EDID_EXT_NUM : edid->extensions;

        /* Find CEA extension */
        for (i = 0; i < edid_ext_num; i++) {
                edid_ext = (char *)edid + EDID_LENGTH * (i + 1);
                /* This block is CEA extension */
                if (edid_ext[0] == 0x02)
                        break;
        }

        if (i == edid_ext_num)
                goto end;

        /* Data block offset in CEA extension block */
        start_offset = 4;
        end_offset = edid_ext[2];

        /*
         * Because HDMI identifier is in Vendor Specific Block,
         * search it from all data blocks of CEA extension.
         */
        for (i = start_offset; i < end_offset;
                /* Increased by data block len */
                i += ((edid_ext[i] & 0x1f) + 1)) {
                /* Find vendor specific block */
                if ((edid_ext[i] >> 5) == VENDOR_BLOCK) {
                        hdmi_id = edid_ext[i + 1] | (edid_ext[i + 2] << 8) |
                                  edid_ext[i + 3] << 16;
                        /* Find HDMI identifier */
                        if (hdmi_id == HDMI_IDENTIFIER)
                                is_hdmi = true;
                        break;
                }
        }

end:
        return is_hdmi;
}
EXPORT_SYMBOL(drm_detect_hdmi_monitor);

/**
 * drm_add_edid_modes - add modes from EDID data, if available
 * @connector: connector we're probing
 * @edid: edid data
 *
 * Add the specified modes to the connector's mode list.
 *
 * Return number of modes added or 0 if we couldn't find any.
 */
int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
{
        int num_modes = 0;
        u32 quirks;

        if (edid == NULL) {
                return 0;
        }
        if (!edid_is_valid(edid)) {
                dev_warn(&connector->dev->pdev->dev, "%s: EDID invalid.\n",
                         drm_get_connector_name(connector));
                return 0;
        }

        quirks = edid_get_quirks(edid);

        num_modes += add_established_modes(connector, edid);
        num_modes += add_standard_modes(connector, edid);
        num_modes += add_detailed_info(connector, edid, quirks);

        if (quirks & (EDID_QUIRK_PREFER_LARGE_60 | EDID_QUIRK_PREFER_LARGE_75))
                edid_fixup_preferred(connector, quirks);

        connector->display_info.serration_vsync = edid->serration_vsync;
        connector->display_info.sync_on_green = edid->sync_on_green;
        connector->display_info.composite_sync = edid->composite_sync;
        connector->display_info.separate_syncs = edid->separate_syncs;
        connector->display_info.blank_to_black = edid->blank_to_black;
        connector->display_info.video_level = edid->video_level;
        connector->display_info.digital = edid->digital;
        connector->display_info.width_mm = edid->width_cm * 10;
        connector->display_info.height_mm = edid->height_cm * 10;
        connector->display_info.gamma = edid->gamma;
        connector->display_info.gtf_supported = edid->default_gtf;
        connector->display_info.standard_color = edid->standard_color;
        connector->display_info.display_type = edid->display_type;
        connector->display_info.active_off_supported = edid->pm_active_off;
        connector->display_info.suspend_supported = edid->pm_suspend;
        connector->display_info.standby_supported = edid->pm_standby;
        connector->display_info.gamma = edid->gamma;

        return num_modes;
}
EXPORT_SYMBOL(drm_add_edid_modes);