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Diffstat (limited to 'src/southbridge/intel/i82801cx/smbus.c')
-rw-r--r--src/southbridge/intel/i82801cx/smbus.c83
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
+}