Add DCON support.

git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2409 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

src/mainboard/olpc/rev_a/cmos.layout

@@ -36,6 +36,7 @@ entries
 424          4       e       7        boot_third
 428          4       h       0        boot_index
 432	     8       h       0        boot_countdown
+440	     1	     e	     0	      dcon_present
 1008         16      h       0        check_sum
 
 enumerations

src/mainboard/olpc/rev_a/mainboard.c

@@ -4,9 +4,69 @@
 #include <device/pci_ids.h>
 #include <device/pci_ops.h>
 #include <arch/io.h>
+#include <pc80/mc146818rtc.h>
 #include "chip.h"
+#include "../southbridge/amd/cs5536/cs5536_smbus2.h"
 
+/* Borrowed from mc146818rtc.c */
 
+#define CMOS_READ(addr) ({ \
+		outb((addr),RTC_PORT(0)); \
+		inb(RTC_PORT(1)); \
+		})
+
+#define CMOS_WRITE(val, addr) ({ \
+		outb((addr),RTC_PORT(0)); \
+		outb((val),RTC_PORT(1)); \
+		})
+
+static void write_bit(unsigned char val) {
+
+	unsigned char byte = CMOS_READ(440 / 8);
+
+	/* Don't change it if its already set */
+
+	if ((byte & 1) == (val & 1))
+		return;
+
+	byte &= ~1;
+	byte |= val & 1;
+	CMOS_WRITE(val, 440/8);
+}
+
+static unsigned short _getsmbusbase(void) {
+	unsigned devfn = PCI_DEVFN(0xf, 0);
+	device_t dev = dev_find_slot(0x0, devfn);
+	unsigned long addr = pci_read_config32(dev, PCI_BASE_ADDRESS_0);
+
+	return (unsigned short) (addr & ~1);
+}
+
+static void init_dcon(void) {
+
+  int ret = 1;
+  unsigned short rev = 0;
+  unsigned short iobase = _getsmbusbase();
+
+  printk_debug("CHECKING FOR DCON (%x)\n", iobase);
+
+  /* Get the IO base for the SMBUS */
+
+  rev = do_smbus_read_word(iobase, 0x0D << 1, 0x00);
+
+  if (rev & 0xDC00) {
+	printk_debug("DCON FOUND - REV %x\n", rev);
+
+	/* Enable the DCON */
+	ret = do_smbus_write_word(iobase, 0x0D << 1, 0x01, 0x0069);
+	if (ret != 0)
+		printk_debug("DCON ENABLE FAILED\n", ret);
+  }
+  else
+	  printk_debug("DCON NOT FOUND (%x)\n", rev);
+
+  write_bit(rev > 0 ? 1 : 0);
+}
 
 static void init(struct device *dev) {
 /*
@@ -32,6 +92,8 @@ static void init(struct device *dev) {
 		pci_write_config8(usb, PCI_INTERRUPT_LINE, usbirq);
 	}
 #endif
+
+	init_dcon();
 	printk_debug("OLPC REVA EXIT %s\n", __FUNCTION__);
 }