1 files changed, 83 insertions, 0 deletions
diff --git a/src/southbridge/intel/i82801cx/smbus.c b/src/southbridge/intel/i82801cx/smbus.c
new file mode 100644
index 0000000000..324f82f286
--- /dev/null
+++ b/src/southbridge/intel/i82801cx/smbus.c
@@ -0,0 +1,83 @@
+#include <smbus.h>
+#include <pci.h>
+#include <arch/io.h>
+#include "i82801cx.h"
+
+#define PM_BUS 0
+#define PM_DEVFN PCI_DEVFN(0x1f,3)
+
+void smbus_enable(void)
+{
+	/* iobase addr */
+	pcibios_write_config_dword(PM_BUS, PM_DEVFN, SMB_BASE,
+							   SMBUS_IO_BASE | PCI_BASE_ADDRESS_SPACE_IO);
+	/* smbus enable */
+	pcibios_write_config_byte(PM_BUS, PM_DEVFN, HOSTC, HST_EN);
+	/* iospace enable */
+	pcibios_write_config_word(PM_BUS, PM_DEVFN, PCI_COMMAND, PCI_COMMAND_IO);
+
+    /* Disable interrupt generation */
+    outb(0, SMBUS_IO_BASE + SMBHSTCTL);
+}
+
+static void smbus_wait_until_ready(void)
+{
+	// Loop while HOST_BUSY
+	while((inb(SMBUS_IO_BASE + SMBHSTSTAT) & 1) == 1) {
+		/* nop */
+	}
+}
+
+static void smbus_wait_until_done(void)
+{
+	unsigned char byte;
+
+	// Loop while HOST_BUSY
+	do {
+		byte = inb(SMBUS_IO_BASE + SMBHSTSTAT);
+	}
+	while((byte &1) == 1);
+
+	// Wait for SUCCESS or error or BYTE_DONE
+	while( (byte & ~1) == 0) {
+		byte = inb(SMBUS_IO_BASE + SMBHSTSTAT);
+	}
+}
+
+int smbus_read_byte(unsigned device, unsigned address, unsigned char *result)
+{
+	unsigned char host_status_register;
+	unsigned char byte;
+
+	smbus_wait_until_ready();
+
+	/* setup transaction */
+	/* disable interrupts */
+	outb(inb(SMBUS_IO_BASE + SMBHSTCTL) & (~1), SMBUS_IO_BASE + SMBHSTCTL);
+	/* set to read from the specified device  */
+	outb(((device & 0x7f) << 1) | 1, SMBUS_IO_BASE + SMBHSTADD);
+	/* set the command/address... */
+	outb(address & 0xFF, SMBUS_IO_BASE + SMBHSTCMD);
+	/* set up for a byte data read */
+	outb((inb(SMBUS_IO_BASE + SMBHSTCTL) & 0xE3) | (0x2 << 2), SMBUS_IO_BASE + SMBHSTCTL);
+
+	/* clear any lingering errors, so the transaction will run */
+	outb(inb(SMBUS_IO_BASE + SMBHSTSTAT), SMBUS_IO_BASE + SMBHSTSTAT);
+
+	/* clear the data byte...*/
+	outb(0, SMBUS_IO_BASE + SMBHSTDAT0);
+
+	/* start the command */
+	outb((inb(SMBUS_IO_BASE + SMBHSTCTL) | 0x40), SMBUS_IO_BASE + SMBHSTCTL);
+
+	/* poll for transaction completion */
+	smbus_wait_until_done();
+
+	host_status_register = inb(SMBUS_IO_BASE + SMBHSTSTAT);
+
+	/* read results of transaction */
+	byte = inb(SMBUS_IO_BASE + SMBHSTDAT0);
+
+	*result = byte;
+	return host_status_register != 0x02;		// return true if !SUCCESS
+}