[CPUFREQ] longhaul - disable PCI mastering around transition.

The spec states that we have to do this, which is *horrid*.

Based on code from: Ken Staton <ken_staton@agilent.com>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 45 insertions, 4 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
index ab0f9f5aac11..8ea545e35b3a 100644
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -29,6 +29,7 @@
 #include <linux/cpufreq.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/pci.h>
 
 #include <asm/msr.h>
 #include <asm/timex.h>
@@ -120,6 +121,11 @@ static void do_powersaver(union msr_longhaul *longhaul,
                         unsigned int clock_ratio_index)
 {
         int version;
+        unsigned long flags;
+        struct pci_dev *dev;
+        int i;
+        u16 pci_cmd;
+        u16 cmd_state[64];
 
         switch (cpu_model) {
         case CPU_EZRA_T:
@@ -137,17 +143,52 @@ static void do_powersaver(union msr_longhaul *longhaul,
         longhaul->bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
         longhaul->bits.EnableSoftBusRatio = 1;
         longhaul->bits.RevisionKey = 0;
-        local_irq_disable();
-        wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
+
+        preempt_disable();
+        local_irq_save(flags);
+
+        /*
+         * get current pci bus master state for all devices
+         * and clear bus master bit
+         */
+        dev = NULL;
+        i = 0;
+        do {
+                dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
+                if (dev != NULL) {
+                        pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
+                        cmd_state[i++] = pci_cmd;
+                        pci_cmd &= ~PCI_COMMAND_MASTER;
+                        pci_write_config_word(dev, PCI_COMMAND, pci_cmd);
+                }
+        } while (dev != NULL);
+
         local_irq_enable();
+
+        __hlt();
+        wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
         __hlt();
 
+        local_irq_disable();
+
+        /* restore pci bus master state for all devices */
+        dev = NULL;
+        i = 0;
+        do {
+                dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
+                if (dev != NULL) {
+                        pci_cmd = cmd_state[i++];
+                        pci_write_config_byte(dev, PCI_COMMAND, pci_cmd);
+                }
+        } while (dev != NULL);
+        local_irq_restore(flags);
+        preempt_enable();
+
+        /* disable bus ratio bit */
         rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);
         longhaul->bits.EnableSoftBusRatio = 0;
         longhaul->bits.RevisionKey = version;
-        local_irq_disable();
         wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
-        local_irq_enable();
 }
 
 /**