Allow the user to override FWH IDSEL on ICH6 and later

Usage:
flashrom -p internal=fwh_idsel=0

Corresponding to flashrom svn r685.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

Log:
flashrom v0.9.0-r670
coreboot table found at 0xcf7f3c00.
Vendor ID: KONTRON, part ID: 986LCD-M
Found chipset "Intel ICH7/ICH7R", enabling flash write...
Setting IDSEL=0 for top 8 MBOK.
This chipset supports the following protocols: LPC,FWH.
Disabling flash write protection for board "Kontron 986LCD-M"... OK.
Calibrating delay loop... OK.
Found chip "SST SST49LF016C" (2048 KB, FWH) at physical address
0xffe00000.
No operations were specified.
Acked-by: Chris Kinney <cmkinne@sandia.gov>

chipset_enable.c

@@ -203,6 +203,7 @@ static int enable_flash_ich_dc(struct pci_dev *dev, const char *name)
 {
 	uint32_t fwh_conf;
 	int i;
+	char *idsel = NULL;
 
 	/* Ignore all legacy ranges below 1 MB. */
 	/* FWH_SEL1 */
@@ -232,6 +233,19 @@ static int enable_flash_ich_dc(struct pci_dev *dev, const char *name)
 			     (0xff0 + i) * 0x100000,
 			     (fwh_conf >> i) & 0x1 ? "en" : "dis");
 
+	if (programmer_param)
+		idsel = strstr(programmer_param, "fwh_idsel=");
+
+	if (idsel) {
+		idsel += strlen("fwh_idsel=");
+		fwh_conf = (uint32_t)strtoul(idsel, NULL, 0);
+
+		/* FIXME: Need to undo this on shutdown. */
+		printf("\nSetting IDSEL=0x%x for top 16 MB", fwh_conf);
+		pci_write_long(dev, 0xd0, fwh_conf);
+		pci_write_word(dev, 0xd4, fwh_conf);
+	}
+
 	return enable_flash_ich(dev, name, 0xdc);
 }