coreboot-kgpe-d16/src/southbridge/nvidia/ck804/ck804_smbus.h

/*
 * Copyright 2004 Tyan Computer
 *  by yhlu@tyan.com
 */
#include <device/smbus_def.h>

#define SMBHSTSTAT 0x1
#define SMBHSTPRTCL  0x0
#define SMBHSTCMD  0x3
#define SMBXMITADD 0x2
#define SMBHSTDAT0 0x4
#define SMBHSTDAT1 0x5

/* Between 1-10 seconds, We should never timeout normally 
 * Longer than this is just painful when a timeout condition occurs.
 */
#define SMBUS_TIMEOUT (100*1000*10)

static inline void smbus_delay(void)
{
	outb(0x80, 0x80);
}

static int smbus_wait_until_ready(unsigned smbus_io_base)
{
	unsigned long loops;
	loops = SMBUS_TIMEOUT;
	do {
		unsigned char val;
		smbus_delay();
		val = inb(smbus_io_base + SMBHSTSTAT);
		if ((val & 0x1f) == 0) {
			break;
		}
		if(loops == (SMBUS_TIMEOUT / 2)) {
			outb((val & 0x1f),smbus_io_base + SMBHSTSTAT);
		}
	} while(--loops);
	return loops?0:-2;
}

static int smbus_wait_until_done(unsigned smbus_io_base)
{
	unsigned long loops;
	loops = SMBUS_TIMEOUT;
	do {
		unsigned char val;
		smbus_delay();
		
		val = inb(smbus_io_base + SMBHSTSTAT);
		if ( (val & 0xff) != 0) {
			break;
		}
	} while(--loops);
	return loops?0:-3;
}
static int do_smbus_recv_byte(unsigned smbus_io_base, unsigned device)
{
        unsigned char global_status_register;
        unsigned char byte;
#if 0 
// Don't need, when you write to PRTCL, the status will be cleared automatically
        if (smbus_wait_until_ready(smbus_io_base) < 0) {
                return -2;
        }
#endif

        /* set the device I'm talking too */
        outb(((device & 0x7f) << 1)|1 , smbus_io_base + SMBXMITADD);
        smbus_delay();
        /* set the command/address... */
        outb(0, smbus_io_base + SMBHSTCMD);
        smbus_delay();
        /* byte data recv */
        outb(0x05, smbus_io_base + SMBHSTPRTCL);
        smbus_delay();

        /* poll for transaction completion */
        if (smbus_wait_until_done(smbus_io_base) < 0) {
                return -3;
        }

        global_status_register = inb(smbus_io_base + SMBHSTSTAT) & 0x80; /* lose check */

        /* read results of transaction */
        byte = inb(smbus_io_base + SMBHSTDAT0);

        if (global_status_register != 0x80) { // lose check, otherwise it should be 0
                return -1;
        }
        return byte;
}
static int do_smbus_send_byte(unsigned smbus_io_base, unsigned device, unsigned char val)
{
        unsigned global_status_register;

#if 0
// Don't need, when you write to PRTCL, the status will be cleared automatically
        if (smbus_wait_until_ready(smbus_io_base) < 0) {
                return -2;
        }
#endif

        outb(val, smbus_io_base + SMBHSTDAT0);
        smbus_delay();

        /* set the device I'm talking too */
        outb(((device & 0x7f) << 1) | 0, smbus_io_base + SMBXMITADD);
        smbus_delay();

        outb(0, smbus_io_base + SMBHSTCMD);
        smbus_delay();

        /* set up for a byte data write */
        outb(0x04, smbus_io_base + SMBHSTPRTCL);
        smbus_delay();

        /* poll for transaction completion */
        if (smbus_wait_until_done(smbus_io_base) < 0) {
                return -3;
        }
        global_status_register = inb(smbus_io_base + SMBHSTSTAT) & 0x80; /* lose check */;

        if (global_status_register != 0x80) {
                return -1;
        }
        return 0;
}
static int do_smbus_read_byte(unsigned smbus_io_base, unsigned device, unsigned address)
{
	unsigned char global_status_register;
	unsigned char byte;
#if 0 
// Don't need, when you write to PRTCL, the status will be cleared automatically
	if (smbus_wait_until_ready(smbus_io_base) < 0) {
		return -2;
	}
#endif
	
	/* set the device I'm talking too */
	outb(((device & 0x7f) << 1)|1 , smbus_io_base + SMBXMITADD);
	smbus_delay();
	/* set the command/address... */
	outb(address & 0xff, smbus_io_base + SMBHSTCMD);
	smbus_delay();
	/* byte data read */
	outb(0x07, smbus_io_base + SMBHSTPRTCL);
	smbus_delay();

	/* poll for transaction completion */
	if (smbus_wait_until_done(smbus_io_base) < 0) {
		return -3;
	}

	global_status_register = inb(smbus_io_base + SMBHSTSTAT) & 0x80; /* lose check */

	/* read results of transaction */
	byte = inb(smbus_io_base + SMBHSTDAT0);

	if (global_status_register != 0x80) { // lose check, otherwise it should be 0
		return -1;
	}
	return byte;
}


static int do_smbus_write_byte(unsigned smbus_io_base, unsigned device, unsigned address, unsigned char val)
{
        unsigned global_status_register;

#if 0
// Don't need, when you write to PRTCL, the status will be cleared automatically
        if (smbus_wait_until_ready(smbus_io_base) < 0) {
                return -2;
        }
#endif

	outb(val, smbus_io_base + SMBHSTDAT0);
	smbus_delay();

        /* set the device I'm talking too */
        outb(((device & 0x7f) << 1) | 0, smbus_io_base + SMBXMITADD);
	smbus_delay();

        outb(address & 0xff, smbus_io_base + SMBHSTCMD);
	smbus_delay();

        /* set up for a byte data write */ 
        outb(0x06, smbus_io_base + SMBHSTPRTCL);
	smbus_delay();

        /* poll for transaction completion */
        if (smbus_wait_until_done(smbus_io_base) < 0) {
                return -3;
        }
        global_status_register = inb(smbus_io_base + SMBHSTSTAT) & 0x80; /* lose check */;

        if (global_status_register != 0x80) {
                return -1;
        }
        return 0;
}