x86: Force enable HPET for CK804 (nForce 4) chipsets

This patch adds a quirk from LinuxBIOS to force enable HPET on
the nVidia CK804 (nForce 4) chipset.

This quirk can very likely support more than just nForce 4
(LinuxBIOS use the same code for nForce 5), and possibly nForce 3,
but I don't have those chipsets, so cannot add and test them.

Tested on an Abit KN9 (CK804).

Signed-off-by: Carlos Corbacho <cathectic@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

 Documentation/kernel-parameters.txt |    3 +-
 arch/x86/kernel/quirks.c            |   37 +++++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 2 deletions(-)

2 files changed, 38 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b2361667839f..a13d69b2217d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -422,7 +422,8 @@ and is between 256 and 4096 characters. It is defined in the file
         hpet=           [X86-32,HPET] option to control HPET usage
                         Format: { enable (default) | disable | force }
                         disable: disable HPET and use PIT instead
-                        force: allow force enabled of undocumented chips (ICH4, VIA)
+                        force: allow force enabled of undocumented chips (ICH4,
+                        VIA, nVidia)
 
         com20020=       [HW,NET] ARCnet - COM20020 chipset
                         Format:
diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
index a4ce1911efdf..5317c40efd13 100644
--- a/arch/x86/kernel/quirks.c
+++ b/arch/x86/kernel/quirks.c
@@ -60,7 +60,8 @@ static enum {
         NONE_FORCE_HPET_RESUME,
         OLD_ICH_FORCE_HPET_RESUME,
         ICH_FORCE_HPET_RESUME,
-        VT8237_FORCE_HPET_RESUME
+        VT8237_FORCE_HPET_RESUME,
+        NVIDIA_FORCE_HPET_RESUME,
 } force_hpet_resume_type;
 
 static void __iomem *rcba_base;
@@ -321,6 +322,37 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235,
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8237,
                          vt8237_force_enable_hpet);
 
+/*
+ * Undocumented chipset feature taken from LinuxBIOS.
+ */
+static void nvidia_force_hpet_resume(void)
+{
+        pci_write_config_dword(cached_dev, 0x44, 0xfed00001);
+        printk(KERN_DEBUG "Force enabled HPET at resume\n");
+}
+
+static void nvidia_force_enable_hpet(struct pci_dev *dev)
+{
+        u32 uninitialized_var(val);
+
+        if (!hpet_force_user || hpet_address || force_hpet_address)
+                return;
+
+        pci_write_config_dword(dev, 0x44, 0xfed00001);
+        pci_read_config_dword(dev, 0x44, &val);
+        force_hpet_address = val & 0xfffffffe;
+        force_hpet_resume_type = NVIDIA_FORCE_HPET_RESUME;
+        printk(KERN_DEBUG "Force enabled HPET at base address 0x%lx\n",
+                force_hpet_address);
+        cached_dev = dev;
+        return;
+}
+
+/* ISA Bridges */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_NVIDIA, 0x0050,
+                        nvidia_force_enable_hpet);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_NVIDIA, 0x0051,
+                        nvidia_force_enable_hpet);
 
 void force_hpet_resume(void)
 {
@@ -334,6 +366,9 @@ void force_hpet_resume(void)
             case VT8237_FORCE_HPET_RESUME:
                 return vt8237_force_hpet_resume();
 
+            case NVIDIA_FORCE_HPET_RESUME:
+                return nvidia_force_hpet_resume();
+
             default:
                 break;
         }