[PATCH/RFC] Enable HPET on VIA8237 southbridge

[Karsten Wiese <annabellesgarden@yahoo.de>]

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Hi,

if you have that chip on your mainboard and want to play with it's
hpet, this might get you going.

   Karsten

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Enable HPET on VIA8237 southbridge

Some BIOSs don't enable the hpet on that chip.
The patch enables it before all the other pci devices.

The hpet's hardware address is set to 0xFED00000,
if the VIA8237 has been identified.

This IS DANGEROUS.
I.e. because the hardware address might be assigned
later in the boot process to somthing else.

Tested succesfully on an K8T800/AMD64 Mobo.
One exception: Timer1 says it can do PERIODIC mode,
but this doesn't work here. One shot is ok.

Signed-off-by: Karsten Wiese <annabellesgraden@yahoo.de>


diff -ur linux-2.6.13-RT/arch/i386/kernel/time_hpet.c linux-2.6.13-RT-kw/arch/i386/kernel/time_hpet.c
--- linux-2.6.13-RT/arch/i386/kernel/time_hpet.c	2005-09-19 15:49:17.000000000 +0200
+++ linux-2.6.13-RT-kw/arch/i386/kernel/time_hpet.c	2005-09-24 00:58:37.000000000 +0200
@@ -223,11 +223,74 @@
 	return use_hpet;
 }
 
+#define HPET_HACK_ENABLE_DANGEROUS 1
+
+#ifdef HPET_HACK_ENABLE_DANGEROUS
+union conf_address {
+	struct {
+		u8	reg;
+		u8	func:	3;
+		u8	dev:	5;
+		u8	bus;
+		u8	reserved:7;
+		u8	enable:	1;
+	} bits;
+	u32	dword;
+};
+
+#include <linux/pci_ids.h>
+
+static void is_hpet_via8237(void)
+{
+	union conf_address ca = {
+		.bits.reg = 0,
+		.bits.dev = 17,
+		.bits.enable = 1
+	};
+	union {
+		struct {
+			u8 control;
+			u8 address[3];
+		} hpet;
+		unsigned raw;
+	} hpet;
+	u32 vendor_id, control;
+
+	control = inl(0xcf8);
+	printk("%X\n", control);
+	outl(ca.dword, 0xcf8);
+	vendor_id = inl(0xcfc);
+	if (vendor_id == (PCI_VENDOR_ID_VIA + (PCI_DEVICE_ID_VIA_8237 << 16))) {
+		hpet.raw = 0xFED00000;
+		hpet.hpet.control = 0x80;
+		ca.bits.reg = 0x68;
+		outl(ca.dword, 0xcf8);
+		outl(hpet.raw, 0xcfc);
+		outl(ca.dword, 0xcf8);
+		hpet_address = (inl(0xcfc) & 0xFFFFFF00);
+		printk(KERN_WARNING "time.c: WARNING: Enabled VIA8237 HPET "
+		       "at %#lx.\n", hpet_address);
+	}
+}
+
+#else
+
+static void is_hpet_via8237(void)
+{
+}
+
+#endif
+
+
 int is_hpet_capable(void)
 {
-	if (!boot_hpet_disable && hpet_address)
-		return 1;
-	return 0;
+	if (boot_hpet_disable)
+		return 0;
+
+        if (!hpet_address)
+		is_hpet_via8237();
+
+	return hpet_address;
 }
 
 static int __init hpet_setup(char* str)