[CPUFREQ] Longhaul - Add VT8235 support

I don't know why it is working and how, but it is working. On my
Epia transition time is by default set to 100us. I'm changing it to
200us. After that I can change frequency from min (x4.0) to max (x7.5)
without lockup. Many times.
There is a paranoid check at a beginning of a patch. Probably dead
code, but I don't have better ideas for CL10000 case at the moment.
Only way to to detect broken chip seems to be looking in log for
spurious interrupts.

Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 50 insertions, 12 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
index 8b5ad308d656..98fbe28affff 100644
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -56,6 +56,7 @@
 /* Flags */
 #define USE_ACPI_C3             (1 << 1)
 #define USE_NORTHBRIDGE         (1 << 2)
+#define USE_VT8235              (1 << 3)
 
 static int cpu_model;
 static unsigned int numscales=16;
@@ -544,20 +545,50 @@ static int enable_arbiter_disable(void)
         if (dev != NULL) {
                 /* Enable access to port 0x22 */
                 pci_read_config_byte(dev, reg, &pci_cmd);
-                if ( !(pci_cmd & 1<<7) ) {
+                if (!(pci_cmd & 1<<7)) {
                         pci_cmd |= 1<<7;
                         pci_write_config_byte(dev, reg, pci_cmd);
+                        pci_read_config_byte(dev, reg, &pci_cmd);
+                        if (!(pci_cmd & 1<<7)) {
+                                printk(KERN_ERR PFX
+                                        "Can't enable access to port 0x22.\n");
+                                return 0;
+                        }
                 }
                 return 1;
         }
         return 0;
 }
 
+static int longhaul_setup_vt8235(void)
+{
+        struct pci_dev *dev;
+        u8 pci_cmd;
+
+        /* Find VT8235 southbridge */
+        dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235, NULL);
+        if (dev != NULL) {
+                /* Set transition time to max */
+                pci_read_config_byte(dev, 0xec, &pci_cmd);
+                pci_cmd &= ~(1 << 2);
+                pci_write_config_byte(dev, 0xec, pci_cmd);
+                pci_read_config_byte(dev, 0xe4, &pci_cmd);
+                pci_cmd &= ~(1 << 7);
+                pci_write_config_byte(dev, 0xe4, pci_cmd);
+                pci_read_config_byte(dev, 0xe5, &pci_cmd);
+                pci_cmd |= 1 << 7;
+                pci_write_config_byte(dev, 0xe5, pci_cmd);
+                return 1;
+        }
+        return 0;
+}
+
 static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 {
         struct cpuinfo_x86 *c = cpu_data;
         char *cpuname=NULL;
         int ret;
+        int vt8235_present;
 
         /* Check what we have on this motherboard */
         switch (c->x86_model) {
@@ -641,12 +672,16 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
                 break;
         };
 
+        /* Doesn't hurt */
+        vt8235_present = longhaul_setup_vt8235();
+
         /* Find ACPI data for processor */
-        acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
-                            &longhaul_walk_callback, NULL, (void *)&pr);
+        acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+                                ACPI_UINT32_MAX, &longhaul_walk_callback,
+                                NULL, (void *)&pr);
 
         /* Check ACPI support for C3 state */
-        if ((pr != NULL) && (longhaul_version == TYPE_POWERSAVER)) {
+        if (pr != NULL && longhaul_version == TYPE_POWERSAVER) {
                 cx = &pr->power.states[ACPI_STATE_C3];
                 if (cx->address > 0 && cx->latency <= 1000) {
                         longhaul_flags |= USE_ACPI_C3;
@@ -658,8 +693,11 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
                 longhaul_flags |= USE_NORTHBRIDGE;
                 goto print_support_type;
         }
-
-        /* No ACPI C3 or we can't use it */
+        /* Use VT8235 southbridge if present */
+        if (longhaul_version == TYPE_POWERSAVER && vt8235_present) {
+                longhaul_flags |= USE_VT8235;
+                goto print_support_type;
+        }
         /* Check ACPI support for bus master arbiter disable */
         if ((pr == NULL) || !(pr->flags.bm_control)) {
                 printk(KERN_ERR PFX
@@ -668,18 +706,18 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
         }
 
 print_support_type:
-        if (!(longhaul_flags & USE_NORTHBRIDGE)) {
-                printk (KERN_INFO PFX "Using ACPI support.\n");
-        } else {
+        if (longhaul_flags & USE_NORTHBRIDGE)
                 printk (KERN_INFO PFX "Using northbridge support.\n");
-        }
+        else if (longhaul_flags & USE_VT8235)
+                printk (KERN_INFO PFX "Using VT8235 support.\n");
+        else
+                printk (KERN_INFO PFX "Using ACPI support.\n");
 
         ret = longhaul_get_ranges();
         if (ret != 0)
                 return ret;
 
-        if ((longhaul_version==TYPE_LONGHAUL_V2 || longhaul_version==TYPE_POWERSAVER) &&
-                 (scale_voltage != 0))
+        if ((longhaul_version != TYPE_LONGHAUL_V1) && (scale_voltage != 0))
                 longhaul_setup_voltagescaling();
 
         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;