sb/intel/i82801gx: Add i2c_block_read to smbus.h

Using i2c_block_read speeds up reading SPD four to fivefold compared
to sequential byte read.

TESTED on Intel D945GCLF.

Change-Id: I6d768a2ba128329168f26445a4fca6921c0c8642
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/18927
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/southbridge/intel/i82801gx/early_smbus.c b/src/southbridge/intel/i82801gx/early_smbus.c
index 93e9d6a6b5af..b8852e91ab1b 100644
--- a/src/southbridge/intel/i82801gx/early_smbus.c
+++ b/src/southbridge/intel/i82801gx/early_smbus.c
@@ -54,3 +54,55 @@ int smbus_read_byte(unsigned int device, unsigned int address)
 {
 	return do_smbus_read_byte(SMBUS_IO_BASE, device, address);
 }
+
+int i2c_block_read(unsigned int device, unsigned int offset, u32 bytes, u8 *buf)
+{
+	u8 status;
+	int bytes_read = 0;
+	if (smbus_wait_until_ready(SMBUS_IO_BASE) < 0)
+		return SMBUS_WAIT_UNTIL_READY_TIMEOUT;
+
+	/* Setup transaction */
+	/* Disable interrupts */
+	outb(inb(SMBUS_IO_BASE + SMBHSTCTL) & (~1), SMBUS_IO_BASE + SMBHSTCTL);
+	/* Set the device I'm talking to */
+	outb((device & 0x7f) << 1, SMBUS_IO_BASE + SMBXMITADD);
+
+	/* SPD offset */
+	outb(offset, SMBUS_IO_BASE + SMBHSTDAT1);
+
+	/* Set up for a i2c block data read */
+	outb((inb(SMBUS_IO_BASE + SMBHSTCTL) & 0xc3) | (0x6 << 2),
+		(SMBUS_IO_BASE + SMBHSTCTL));
+
+	/* Clear any lingering errors, so the transaction will run */
+	outb(inb(SMBUS_IO_BASE + SMBHSTSTAT), SMBUS_IO_BASE + SMBHSTSTAT);
+	/* Start the command */
+	outb((inb(SMBUS_IO_BASE + SMBHSTCTL) | 0x40),
+	     SMBUS_IO_BASE + SMBHSTCTL);
+
+	while (!(inb(SMBUS_IO_BASE + SMBHSTSTAT) & 1))
+		;
+	/* Poll for transaction completion */
+	do {
+		status = inb(SMBUS_IO_BASE + SMBHSTSTAT);
+		if (status & ((1 << 4) | /* FAILED */
+			      (1 << 3) | /* BUS ERR */
+			      (1 << 2))) /* DEV ERR */
+			return SMBUS_ERROR;
+
+		if (status & 0x80) { /* Byte done */
+			*buf = inb(SMBUS_IO_BASE + SMBBLKDAT);
+			buf++;
+			bytes_read++;
+			if (--bytes == 1) {
+				/* indicate that next byte is the last one */
+				outb(inb(SMBUS_IO_BASE + SMBHSTCTL) | 0x20,
+					 SMBUS_IO_BASE + SMBHSTCTL);
+			}
+			outb(status, SMBUS_IO_BASE + SMBHSTSTAT);
+		}
+	} while (status & 0x01);
+
+	return bytes_read;
+}