path: root/hw/xfree86/ddc/ddc.c

/* xf86DDC.c 
 * 
 * Copyright 1998,1999 by Egbert Eich <Egbert.Eich@Physik.TU-Darmstadt.DE>
 */

/*
 * A note on terminology.  DDC1 is the original dumb serial protocol, and
 * can only do up to 128 bytes of EDID.  DDC2 is I2C-encapsulated and
 * introduces extension blocks.  EDID is the old display identification
 * block, DisplayID is the new one.
 */

#ifdef HAVE_XORG_CONFIG_H
#include <xorg-config.h>
#endif

#include "misc.h"
#include "xf86.h"
#include "xf86_OSproc.h"
#include "xf86DDC.h"
#include <string.h>

#define RETRIES 4

typedef enum {
    DDCOPT_NODDC1,
    DDCOPT_NODDC2,
    DDCOPT_NODDC
} DDCOpts;

static const OptionInfoRec DDCOptions[] = {
    { DDCOPT_NODDC1,	"NoDDC1",	OPTV_BOOLEAN,	{0},	FALSE },
    { DDCOPT_NODDC2,	"NoDDC2",	OPTV_BOOLEAN,	{0},	FALSE },
    { DDCOPT_NODDC,	"NoDDC",	OPTV_BOOLEAN,	{0},	FALSE },
    { -1,		NULL,		OPTV_NONE,	{0},	FALSE },
};

/* DDC1 */

static int
find_start(unsigned int *ptr)
{
    unsigned int comp[9], test[9];
    int i,j;
  
    for (i=0;i<9;i++){
	comp[i] = *(ptr++);
	test[i] = 1;
    }
    for (i=0;i<127;i++){
	for (j=0;j<9;j++){
	    test[j] = test[j] & !(comp[j] ^ *(ptr++));
	}
    }
    for (i=0;i<9;i++)
	if (test[i]) return i+1;
    return -1;
}

static unsigned char *
find_header(unsigned char *block)
{
    unsigned char *ptr, *head_ptr, *end;
    unsigned char header[]={0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00};
 
    ptr = block;
    end = block + EDID1_LEN;
    while (ptr<end) {
	int i;
	head_ptr = ptr;
	for (i=0;i<8;i++){
	    if (header[i] != *(head_ptr++)) break;
	    if (head_ptr == end) head_ptr = block;
	}
	if (i==8) break;
	ptr++; 
    }
    if (ptr == end) return NULL;
    return ptr;
}

static unsigned char *
resort(unsigned char *s_block)
{
    unsigned char *d_new, *d_ptr, *d_end, *s_ptr, *s_end;
    unsigned char tmp;

    s_end = s_block + EDID1_LEN;
    d_new = malloc(EDID1_LEN);
    if (!d_new) return NULL;
    d_end = d_new + EDID1_LEN;

    s_ptr = find_header(s_block);
    if (!s_ptr) return NULL;
    for (d_ptr=d_new;d_ptr<d_end;d_ptr++){
	tmp = *(s_ptr++);
	*d_ptr = tmp; 
	if (s_ptr == s_end) s_ptr = s_block;
    }
    free(s_block);
    return d_new;
}

static int
DDC_checksum(const unsigned char *block, int len)
{
    int i, result = 0;
    int not_null = 0;
    
    for (i=0;i<len;i++) {
	not_null |= block[i];
	result += block[i];
    }
    
#ifdef DEBUG
    if (result & 0xFF) ErrorF("DDC checksum not correct\n");
    if (!not_null) ErrorF("DDC read all Null\n");
#endif

    /* catch the trivial case where all bytes are 0 */
    if (!not_null) return 1;

    return result&0xFF;
}

static unsigned char *
GetEDID_DDC1(unsigned int *s_ptr)
{
    unsigned char *d_block, *d_pos;
    unsigned int *s_pos, *s_end;
    int s_start;
    int i,j;
    s_start = find_start(s_ptr);
    if (s_start==-1) return NULL;
    s_end = s_ptr + NUM;
    s_pos = s_ptr + s_start;
    d_block=malloc(EDID1_LEN);
    if (!d_block) return NULL;
    d_pos = d_block;
    for (i=0;i<EDID1_LEN;i++) {
	for (j=0;j<8;j++) {
	    *d_pos <<= 1;
	    if (*s_pos) {
		*d_pos |= 0x01;
	    }
	    s_pos++; if (s_pos == s_end) s_pos=s_ptr;
	};
	s_pos++; if (s_pos == s_end) s_pos=s_ptr;
	d_pos++;
    }
    free(s_ptr);
    if (d_block && DDC_checksum(d_block,EDID1_LEN)) {
	free(d_block);
	return NULL;
    }
    return (resort(d_block));
}

/* fetch entire EDID record; DDC bit needs to be masked */
static unsigned int * 
FetchEDID_DDC1(register ScrnInfoPtr pScrn,
	       register unsigned int (*read_DDC)(ScrnInfoPtr))
{
    int count = NUM;
    unsigned int *ptr, *xp;

    ptr=xp=malloc(sizeof(int)*NUM);

    if (!ptr)  return NULL;
    do {
	/* wait for next retrace */
	*xp = read_DDC(pScrn);
	xp++;
    } while(--count);
    return ptr;
}

/* test if DDC1  return 0 if not */
static Bool
TestDDC1(ScrnInfoPtr pScrn, unsigned int (*read_DDC)(ScrnInfoPtr))
{
    int old, count;

    old = read_DDC(pScrn);
    count = HEADER * BITS_PER_BYTE;
    do {
	/* wait for next retrace */
	if (old != read_DDC(pScrn)) break;
    } while(count--);
    return count;
}

/* 
 * read EDID record , pass it to callback function to interpret.
 * callback function will store it for further use by calling
 * function; it will also decide if we need to reread it 
 */
static unsigned char *
EDIDRead_DDC1(ScrnInfoPtr pScrn, DDC1SetSpeedProc DDCSpeed, 
              unsigned int (*read_DDC)(ScrnInfoPtr))
{
    unsigned char *EDID_block = NULL;
    int count = RETRIES;

    if (!read_DDC) { 
	xf86DrvMsg(pScrn->scrnIndex, X_PROBED, 
		   "chipset doesn't support DDC1\n");
	return NULL; 
    };

    if (TestDDC1(pScrn,read_DDC)==-1) { 
	xf86DrvMsg(pScrn->scrnIndex, X_PROBED, "No DDC signal\n"); 
	return NULL; 
    };

    if (DDCSpeed) DDCSpeed(pScrn,DDC_FAST);
    do {
	EDID_block = GetEDID_DDC1(FetchEDID_DDC1(pScrn,read_DDC)); 
	count --;
    } while (!EDID_block && count);
    if (DDCSpeed) DDCSpeed(pScrn,DDC_SLOW);

    return EDID_block;
}

/**
 * Attempts to probe the monitor for EDID information, if NoDDC and NoDDC1 are
 * unset.  EDID information blocks are interpreted and the results returned in
 * an xf86MonPtr.
 *
 * This function does not affect the list of modes used by drivers -- it is up
 * to the driver to decide policy on what to do with EDID information.
 *
 * @return pointer to a new xf86MonPtr containing the EDID information.
 * @return NULL if no monitor attached or failure to interpret the EDID.
 */
xf86MonPtr
xf86DoEDID_DDC1(
    int scrnIndex, DDC1SetSpeedProc DDC1SetSpeed, 
    unsigned int (*DDC1Read)(ScrnInfoPtr)
)
{
    ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
    unsigned char *EDID_block = NULL;
    xf86MonPtr tmp = NULL;
    int sigio;
    /* Default DDC and DDC1 to enabled. */
    Bool noddc = FALSE, noddc1 = FALSE;
    OptionInfoPtr options;

    options = xnfalloc(sizeof(DDCOptions));
    (void)memcpy(options, DDCOptions, sizeof(DDCOptions));
    xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, options);

    xf86GetOptValBool(options, DDCOPT_NODDC, &noddc);
    xf86GetOptValBool(options, DDCOPT_NODDC1, &noddc1);
    free(options);
    
    if (noddc || noddc1)
	return NULL;
    
    sigio = xf86BlockSIGIO();
    EDID_block = EDIDRead_DDC1(pScrn,DDC1SetSpeed,DDC1Read);
    xf86UnblockSIGIO(sigio);

    if (EDID_block){
	tmp = xf86InterpretEDID(scrnIndex,EDID_block);
    }
#ifdef DEBUG
	else ErrorF("No EDID block returned\n");
    if (!tmp)
	ErrorF("Cannot interpret EDID block\n");
#endif
	return tmp;
}

/* DDC2 */

static I2CDevPtr
DDC2MakeDevice(I2CBusPtr pBus, int address, char *name)
{
    I2CDevPtr dev = NULL;

    if (!(dev = xf86I2CFindDev(pBus, address))) {
	dev = xf86CreateI2CDevRec();
	dev->DevName = name;
	dev->SlaveAddr = address;
	dev->ByteTimeout = 2200; /* VESA DDC spec 3 p. 43 (+10 %) */
	dev->StartTimeout = 550;
	dev->BitTimeout = 40;
	dev->AcknTimeout = 40;

	dev->pI2CBus = pBus;
	if (!xf86I2CDevInit(dev)) {
	    xf86DrvMsg(pBus->scrnIndex, X_PROBED, "No DDC2 device\n");
	    return NULL;
	}
    }

    return dev;
}

static I2CDevPtr
DDC2Init(int scrnIndex, I2CBusPtr pBus)
{
    I2CDevPtr dev = NULL;

    /*
     * Slow down the bus so that older monitors don't 
     * miss things.
     */
    pBus->RiseFallTime = 20;
 
    dev = DDC2MakeDevice(pBus, 0x00A0, "ddc2");
    if (xf86I2CProbeAddress(pBus, 0x0060))
	DDC2MakeDevice(pBus, 0x0060, "E-EDID segment register");

    return dev;
}

/* Mmmm, smell the hacks */
static void
EEDIDStop(I2CDevPtr d)
{
}

/* block is the EDID block number.  a segment is two blocks. */
static Bool
DDC2Read(I2CDevPtr dev, int block, unsigned char *R_Buffer)
{
    unsigned char W_Buffer[1];
    int i, segment;
    I2CDevPtr seg;
    void (*stop)(I2CDevPtr);

    for (i = 0; i < RETRIES; i++) {
	/* Stop bits reset the segment pointer to 0, so be careful here. */
	segment = block >> 1;
	if (segment) {
	    Bool b;
	    
	    if (!(seg = xf86I2CFindDev(dev->pI2CBus, 0x0060)))
		return FALSE;

	    W_Buffer[0] = segment;

	    stop = dev->pI2CBus->I2CStop;
	    dev->pI2CBus->I2CStop = EEDIDStop;

	    b = xf86I2CWriteRead(seg, W_Buffer, 1, NULL, 0);

	    dev->pI2CBus->I2CStop = stop;
	    if (!b) {
		dev->pI2CBus->I2CStop(dev);
		continue;
	    }
	}

	W_Buffer[0] = (block & 0x01) * EDID1_LEN;

	if (xf86I2CWriteRead(dev, W_Buffer, 1, R_Buffer, EDID1_LEN)) {
	    if (!DDC_checksum(R_Buffer, EDID1_LEN))
		return TRUE;
	}
    }
 
    return FALSE;
}

/**
 * Attempts to probe the monitor for EDID information, if NoDDC and NoDDC2 are
 * unset.  EDID information blocks are interpreted and the results returned in
 * an xf86MonPtr.  Unlike xf86DoEDID_DDC[12](), this function will return
 * the complete EDID data, including all extension blocks, if the 'complete'
 * parameter is TRUE;
 *
 * This function does not affect the list of modes used by drivers -- it is up
 * to the driver to decide policy on what to do with EDID information.
 *
 * @return pointer to a new xf86MonPtr containing the EDID information.
 * @return NULL if no monitor attached or failure to interpret the EDID.
 */
xf86MonPtr
xf86DoEEDID(int scrnIndex, I2CBusPtr pBus, Bool complete)
{
    ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
    unsigned char *EDID_block = NULL;
    xf86MonPtr tmp = NULL;
    I2CDevPtr dev = NULL;
    /* Default DDC and DDC2 to enabled. */
    Bool noddc = FALSE, noddc2 = FALSE;
    OptionInfoPtr options;

    options = malloc(sizeof(DDCOptions));
    if (!options)
	return NULL;
    memcpy(options, DDCOptions, sizeof(DDCOptions));
    xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, options);

    xf86GetOptValBool(options, DDCOPT_NODDC, &noddc);
    xf86GetOptValBool(options, DDCOPT_NODDC2, &noddc2);
    free(options);

    if (noddc || noddc2)
	return NULL;

    if (!(dev = DDC2Init(scrnIndex, pBus)))
	return NULL;

    EDID_block = calloc(1, EDID1_LEN);
    if (!EDID_block)
	return NULL;

    if (DDC2Read(dev, 0, EDID_block)) {
	int i, n = EDID_block[0x7e];

	if (complete && n) {
	    EDID_block = realloc(EDID_block, EDID1_LEN * (1+n));

	    for (i = 0; i < n; i++)
		DDC2Read(dev, i+1, EDID_block + (EDID1_LEN * (1+i)));
	}

	tmp = xf86InterpretEEDID(scrnIndex, EDID_block);
    }

    if (tmp && complete)
	tmp->flags |= MONITOR_EDID_COMPLETE_RAWDATA;

    return tmp;
}

/**
 * Attempts to probe the monitor for EDID information, if NoDDC and NoDDC2 are
 * unset.  EDID information blocks are interpreted and the results returned in
 * an xf86MonPtr.
 *
 * This function does not affect the list of modes used by drivers -- it is up
 * to the driver to decide policy on what to do with EDID information.
 *
 * @return pointer to a new xf86MonPtr containing the EDID information.
 * @return NULL if no monitor attached or failure to interpret the EDID.
 */
xf86MonPtr
xf86DoEDID_DDC2(int scrnIndex, I2CBusPtr pBus)
{
    return xf86DoEEDID(scrnIndex, pBus, FALSE);
}

/* XXX write me */
static void *
DDC2ReadDisplayID(void)
{
    return FALSE;
}

/**
 * Attempts to probe the monitor for DisplayID information, if NoDDC and
 * NoDDC2 are unset.  DisplayID blocks are interpreted and the results
 * returned in an xf86MonPtr.
 *
 * This function does not affect the list of modes used by drivers -- it is up
 * to the driver to decide policy on what to do with DisplayID information.
 *
 * @return pointer to a new xf86MonPtr containing the DisplayID information.
 * @return NULL if no monitor attached or failure to interpret the DisplayID.
 */
xf86MonPtr
xf86DoDisplayID(int scrnIndex, I2CBusPtr pBus)
{
    ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
    unsigned char *did = NULL;
    xf86MonPtr tmp = NULL;
    I2CDevPtr dev = NULL;
    /* Default DDC and DDC2 to enabled. */
    Bool noddc = FALSE, noddc2 = FALSE;
    OptionInfoPtr options;

    options = malloc(sizeof(DDCOptions));
    if (!options)
	return NULL;
    memcpy(options, DDCOptions, sizeof(DDCOptions));
    xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, options);

    xf86GetOptValBool(options, DDCOPT_NODDC, &noddc);
    xf86GetOptValBool(options, DDCOPT_NODDC2, &noddc2);
    free(options);

    if (noddc || noddc2)
	return NULL;

    if (!(dev = DDC2Init(scrnIndex, pBus)))
	return NULL;

    if ((did = DDC2ReadDisplayID())) {
	tmp = calloc(1, sizeof(*tmp));
	if (!tmp)
	    return NULL;

	tmp->scrnIndex = scrnIndex;
	tmp->flags |= MONITOR_DISPLAYID;
	tmp->rawData = did;
    }

    return tmp;
}