x86: force enable HPET on VT8235/8237 chipsets

This patch adds quirks to force enable HPET on Via VT8235 and
VT8237 chipsets. The datasheet for 8237 documents HPET
functionality (although wrongly) whereas HPET is undocumented
for 8235.

Tested on A7V880 (8237) and K7VT4A+ (8235) boards.

tglx: depends on the force_hept commandline option
Signed-off-by: Udo A. Steinberg <us15@os.inf.tu-dresden.de>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/quirks.c

@@ -59,7 +59,8 @@ unsigned long force_hpet_address;
 static enum {
 	NONE_FORCE_HPET_RESUME,
 	OLD_ICH_FORCE_HPET_RESUME,
-	ICH_FORCE_HPET_RESUME
+	ICH_FORCE_HPET_RESUME,
+	VT8237_FORCE_HPET_RESUME
 } force_hpet_resume_type;
 
 static void __iomem *rcba_base;
@@ -240,6 +241,69 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801EB_0,
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801EB_12,
 			 old_ich_force_enable_hpet);
 
+
+static void vt8237_force_hpet_resume(void)
+{
+	u32 val;
+
+	if (!force_hpet_address || !cached_dev)
+		return;
+
+	val = 0xfed00000 | 0x80;
+	pci_write_config_dword(cached_dev, 0x68, val);
+
+	pci_read_config_dword(cached_dev, 0x68, &val);
+	if (val & 0x80)
+		printk(KERN_DEBUG "Force enabled HPET at resume\n");
+	else
+		BUG();
+}
+
+static void vt8237_force_enable_hpet(struct pci_dev *dev)
+{
+	u32 uninitialized_var(val);
+
+	if (!hpet_force_user || hpet_address || force_hpet_address)
+		return;
+
+	pci_read_config_dword(dev, 0x68, &val);
+	/*
+	 * Bit 7 is HPET enable bit.
+	 * Bit 31:10 is HPET base address (contrary to what datasheet claims)
+	 */
+	if (val & 0x80) {
+		force_hpet_address = (val & ~0x3ff);
+		printk(KERN_DEBUG "HPET at base address 0x%lx\n",
+			       force_hpet_address);
+		return;
+	}
+
+	/*
+	 * HPET is disabled. Trying enabling at FED00000 and check
+	 * whether it sticks
+	 */
+	val = 0xfed00000 | 0x80;
+	pci_write_config_dword(dev, 0x68, val);
+
+	pci_read_config_dword(dev, 0x68, &val);
+	if (val & 0x80) {
+		force_hpet_address = (val & ~0x3ff);
+		printk(KERN_DEBUG "Force enabled HPET at base address 0x%lx\n",
+			       force_hpet_address);
+		cached_dev = dev;
+		force_hpet_resume_type = VT8237_FORCE_HPET_RESUME;
+		return;
+	}
+
+	printk(KERN_DEBUG "Failed to force enable HPET\n");
+}
+
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235,
+			 vt8237_force_enable_hpet);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8237,
+			 vt8237_force_enable_hpet);
+
+
 void force_hpet_resume(void)
 {
 	switch (force_hpet_resume_type) {
@@ -249,6 +313,9 @@ void force_hpet_resume(void)
 	    case OLD_ICH_FORCE_HPET_RESUME:
 		return old_ich_force_hpet_resume();
 
+	    case VT8237_FORCE_HPET_RESUME:
+		return vt8237_force_hpet_resume();
+
 	    default:
 		break;
 	}