[CPUFREQ] Longhaul - Fix up powersaver assumptions.

ACPI PM2 register was fallback for "Longhaul ver. 1" CPU's.
My assumption that this register isn't present at
"PowerSaver" motherboards is so far true, but current code
will not work correctly in other case. There are three possible
supports: ACPI C3, PM2 and northbridge. That was my assumption
that ACPI C3 and northbridge is for PS and northbridge and PM2
is for V1. In current code we can only check if it is ACPI
support or not by port22_en. So remove port22_en and add
longhaul_flags. If USE_ACPI_C3 and USE_NORTHBRIDGE are both
clear then it means ACPI PM2 support. Also change order of
support probe from ACPI C3, PM2, northbridge to ACPI C3,
northbridge, ACPI PM2. Paranoid protection against port 0x22
cast as ACPI PM2 register. Bit 1 clear in such case - lockup
on AGP DMA. And obvious (now) fixup for do_powersaver. Use
cx->address only for ACPI C3 ("PowerSaver" processor using
PM2 support).
Signed-off-by: Rafa Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>

arch/i386/kernel/cpu/cpufreq/longhaul.c

@@ -52,6 +52,10 @@
 #define	CPU_EZRA_T	4
 #define	CPU_NEHEMIAH	5
 
+/* Flags */
+#define USE_ACPI_C3		(1 << 1)
+#define USE_NORTHBRIDGE		(1 << 2)
+
 static int cpu_model;
 static unsigned int numscales=16;
 static unsigned int fsb;
@@ -68,7 +72,7 @@ static unsigned int minmult, maxmult;
 static int can_scale_voltage;
 static struct acpi_processor *pr = NULL;
 static struct acpi_processor_cx *cx = NULL;
-static int port22_en;
+static u8 longhaul_flags;
 
 /* Module parameters */
 static int scale_voltage;
@@ -80,7 +84,6 @@ static int ignore_latency;
 /* Clock ratios multiplied by 10 */
 static int clock_ratio[32];
 static int eblcr_table[32];
-static unsigned int highest_speed, lowest_speed; /* kHz */
 static int longhaul_version;
 static struct cpufreq_frequency_table *longhaul_table;
 
@@ -178,7 +181,7 @@ static void do_powersaver(int cx_address, unsigned int clock_ratio_index)
 	safe_halt();
 	/* Change frequency on next halt or sleep */
 	wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
-	if (port22_en) {
+	if (!cx_address) {
 		ACPI_FLUSH_CPU_CACHE();
 		/* Invoke C1 */
 		halt();
@@ -189,7 +192,6 @@ static void do_powersaver(int cx_address, unsigned int clock_ratio_index)
 		/* Dummy op - must do something useless after P_LVL3 read */
 		t = inl(acpi_fadt.xpm_tmr_blk.address);
 	}
-
 	/* Disable bus ratio bit */
 	local_irq_disable();
 	longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
@@ -243,15 +245,14 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
 	outb(0xFF,0xA1);	/* Overkill */
 	outb(0xFE,0x21);	/* TMR0 only */
 
-	if (pr->flags.bm_control) {
+	if (longhaul_flags & USE_NORTHBRIDGE) {
+		/* Disable AGP and PCI arbiters */
+		outb(3, 0x22);
+	} else if ((pr != NULL) && pr->flags.bm_control) {
  		/* Disable bus master arbitration */
 		acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1,
 				  ACPI_MTX_DO_NOT_LOCK);
-	} else if (port22_en) {
-		/* Disable AGP and PCI arbiters */
-		outb(3, 0x22);
 	}
-
 	switch (longhaul_version) {
 
 	/*
@@ -278,22 +279,25 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
 	 * to work in practice.
 	 */
 	case TYPE_POWERSAVER:
-		/* Don't allow wakeup */
-		acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0,
-				  ACPI_MTX_DO_NOT_LOCK);
-		do_powersaver(cx->address, clock_ratio_index);
+		if (longhaul_flags & USE_ACPI_C3) {
+			/* Don't allow wakeup */
+			acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0,
+					  ACPI_MTX_DO_NOT_LOCK);
+			do_powersaver(cx->address, clock_ratio_index);
+		} else {
+			do_powersaver(0, clock_ratio_index);
+		}
 		break;
 	}
 
-	if (pr->flags.bm_control) {
+	if (longhaul_flags & USE_NORTHBRIDGE) {
+		/* Enable arbiters */
+		outb(0, 0x22);
+	} else if ((pr != NULL) && pr->flags.bm_control) {
 		/* Enable bus master arbitration */
 		acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0,
 				  ACPI_MTX_DO_NOT_LOCK);
-	} else if (port22_en) {
-		/* Enable arbiters */
-		outb(0, 0x22);
 	}
-
 	outb(pic2_mask,0xA1);	/* restore mask */
 	outb(pic1_mask,0x21);
 
@@ -691,27 +695,32 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 	/* Find ACPI data for processor */
 	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
 			    &longhaul_walk_callback, NULL, (void *)&pr);
-	if (pr == NULL)
-		goto err_acpi;
 
-	if (longhaul_version == TYPE_POWERSAVER) {
-		/* Check ACPI support for C3 state */
+	/* Check ACPI support for C3 state */
+	if ((pr != NULL) && (longhaul_version == TYPE_POWERSAVER)) {
 		cx = &pr->power.states[ACPI_STATE_C3];
 		if (cx->address > 0 &&
 		   (cx->latency <= 1000 || ignore_latency != 0) ) {
+			longhaul_flags |= USE_ACPI_C3;
 			goto print_support_type;
 		}
 	}
+	/* Check if northbridge is friendly */
+	if (enable_arbiter_disable()) {
+		longhaul_flags |= USE_NORTHBRIDGE;
+		goto print_support_type;
+	}
+
+	/* No ACPI C3 or we can't use it */
 	/* Check ACPI support for bus master arbiter disable */
-	if (!pr->flags.bm_control) {
-		if (enable_arbiter_disable()) {
-			port22_en = 1;
-		} else {
-			goto err_acpi;
-		}
+	if ((pr == NULL) || !(pr->flags.bm_control)) {
+		printk(KERN_ERR PFX
+			"No ACPI support. Unsupported northbridge.\n");
+		return -ENODEV;
 	}
+
 print_support_type:
-	if (!port22_en) {
+	if (!(longhaul_flags & USE_NORTHBRIDGE)) {
 		printk (KERN_INFO PFX "Using ACPI support.\n");
 	} else {
 		printk (KERN_INFO PFX "Using northbridge support.\n");
@@ -736,10 +745,6 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 	cpufreq_frequency_table_get_attr(longhaul_table, policy->cpu);
 
 	return 0;
-
-err_acpi:
-	printk(KERN_ERR PFX "No ACPI support. Unsupported northbridge. Aborting.\n");
-	return -ENODEV;
 }
 
 static int __devexit longhaul_cpu_exit(struct cpufreq_policy *policy)