[PATCH] Longhaul - Add voltage scaling to driver

["Rafał Bilski" <rafalbilski@interia.pl>]

Rename option "dont_scale_voltage" to "scale_voltage" because 
don't will be default.
Use "pos" for calculating voltage. In this way driver don't need 
to know mV value or low level value. Simply min U is one pos and 
max U is second pos. All pos between these two are used.
Assume that min U is for min f and max U for max f. For frequency 
between min and max calculate pos based on difference between 
current frequency and min f.
Values in mobile VRM table changed to values from 
C3-M datasheet.
 
Signed-off-by: Rafa³ Bilski <rafalbilski@interia.pl>

> =0 is unneeded for static vars.

Fixed.

> Either keep them on one line, or prepend unsigned int to all of them.
> Doing it the way you did it is annoying when you're grepping for a type.

Fixed.

> There also seemed to be some whitespace (using spaces instead of tabs?)
> problems in the longhaul.h diff, so give that a quick doublecheck too.
> 

I was using mcedit once. Looks like editor did it. Now this should be 
fixed by Vim.

> What CPUs have you tested this on so far btw ?
> 
> 		Dave

One only (mobile), thats why I'm setting "don't" as default. Other 
VIA processors on all mainboards seems to have CPU voltage constant.
They are reporting Mobile VRM, max as 1.75V, min as 0.6V and bit 0 
have clear. Value written to Longhaul MSR is left unchanged, but 
don't have any effect.

Rafa³

---

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -53,19 +53,26 @@ #define	CPU_EZRA_T	4
 #define	CPU_NEHEMIAH	5
 
 static int cpu_model;
-static unsigned int numscales=16, numvscales;
+static unsigned int numscales=16;
 static unsigned int fsb;
-static int minvid, maxvid;
+
+static struct mV_pos *vrm_mV_table;
+static unsigned char *mV_vrm_table;
+struct f_msr {
+	unsigned char vrm;
+};
+static struct f_msr f_msr_table[32];
+
+static unsigned int highest_speed, lowest_speed; /* kHz */
 static unsigned int minmult, maxmult;
 static int can_scale_voltage;
-static int vrmrev;
 static struct acpi_processor *pr = NULL;
 static struct acpi_processor_cx *cx = NULL;
-static int port22_en = 0;
+static int port22_en;
 
 /* Module parameters */
-static int dont_scale_voltage;
-static int ignore_latency = 0;
+static int scale_voltage;
+static int ignore_latency;
 
 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "longhaul", msg)
 
@@ -73,7 +80,6 @@ #define dprintk(msg...) cpufreq_debug_pr
 /* Clock ratios multiplied by 10 */
 static int clock_ratio[32];
 static int eblcr_table[32];
-static int voltage_table[32];
 static unsigned int highest_speed, lowest_speed; /* kHz */
 static int longhaul_version;
 static struct cpufreq_frequency_table *longhaul_table;
@@ -163,6 +169,11 @@ static void do_powersaver(int cx_address
 	longhaul.bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
 	longhaul.bits.EnableSoftBusRatio = 1;
 
+	if (can_scale_voltage) {
+		longhaul.bits.SoftVID = f_msr_table[clock_ratio_index].vrm;
+		longhaul.bits.EnableSoftVID = 1;
+	}
+
 	/* Sync to timer tick */
 	safe_halt();
 	/* Change frequency on next halt or sleep */
@@ -454,53 +465,57 @@ static int __init longhaul_get_ranges(vo
 static void __init longhaul_setup_voltagescaling(void)
 {
 	union msr_longhaul longhaul;
+	struct mV_pos minvid, maxvid;
+	unsigned int j, speed, pos, kHz_step, numvscales;
 
-	rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
-
-	if (!(longhaul.bits.RevisionID & 1))
+	rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);
+	if (!(longhaul.bits.RevisionID & 1)) {
+		printk(KERN_INFO PFX "Voltage scaling not supported by CPU.\n");
 		return;
+	}
+
+	if (!longhaul.bits.VRMRev) {
+		printk (KERN_INFO PFX "VRM 8.5\n");
+		vrm_mV_table = &vrm85_mV[0];
+		mV_vrm_table = &mV_vrm85[0];
+	} else {
+		printk (KERN_INFO PFX "Mobile VRM\n");
+		vrm_mV_table = &mobilevrm_mV[0];
+		mV_vrm_table = &mV_mobilevrm[0];
+	}
 
-	minvid = longhaul.bits.MinimumVID;
-	maxvid = longhaul.bits.MaximumVID;
-	vrmrev = longhaul.bits.VRMRev;
+	minvid = vrm_mV_table[longhaul.bits.MinimumVID];
+	maxvid = vrm_mV_table[longhaul.bits.MaximumVID];
+	numvscales = maxvid.pos - minvid.pos + 1;
+	kHz_step = (highest_speed - lowest_speed) / numvscales;
 
-	if (minvid == 0 || maxvid == 0) {
+	if (minvid.mV == 0 || maxvid.mV == 0 || minvid.mV > maxvid.mV) {
 		printk (KERN_INFO PFX "Bogus values Min:%d.%03d Max:%d.%03d. "
 					"Voltage scaling disabled.\n",
-					minvid/1000, minvid%1000, maxvid/1000, maxvid%1000);
+					minvid.mV/1000, minvid.mV%1000, maxvid.mV/1000, maxvid.mV%1000);
 		return;
 	}
 
-	if (minvid == maxvid) {
+	if (minvid.mV == maxvid.mV) {
 		printk (KERN_INFO PFX "Claims to support voltage scaling but min & max are "
 				"both %d.%03d. Voltage scaling disabled\n",
-				maxvid/1000, maxvid%1000);
+				maxvid.mV/1000, maxvid.mV%1000);
 		return;
 	}
 
-	if (vrmrev==0) {
-		dprintk ("VRM 8.5\n");
-		memcpy (voltage_table, vrm85scales, sizeof(voltage_table));
-		numvscales = (voltage_table[maxvid]-voltage_table[minvid])/25;
-	} else {
-		dprintk ("Mobile VRM\n");
-		memcpy (voltage_table, mobilevrmscales, sizeof(voltage_table));
-		numvscales = (voltage_table[maxvid]-voltage_table[minvid])/5;
+	printk(KERN_INFO PFX "Max VID=%d.%03d  Min VID=%d.%03d, %d possible voltage scales\n",
+		maxvid.mV/1000, maxvid.mV%1000,
+		minvid.mV/1000, minvid.mV%1000,
+		numvscales);
+	
+	j = 0;
+	while (longhaul_table[j].frequency != CPUFREQ_TABLE_END) {
+		speed = longhaul_table[j].frequency;
+		pos = (speed - lowest_speed) / kHz_step + minvid.pos;
+		f_msr_table[longhaul_table[j].index].vrm = mV_vrm_table[pos];
+		j++;
 	}
 
-	/* Current voltage isn't readable at first, so we need to
-	   set it to a known value. The spec says to use maxvid */
-	longhaul.bits.RevisionKey = longhaul.bits.RevisionID;	/* FIXME: This is bad. */
-	longhaul.bits.EnableSoftVID = 1;
-	longhaul.bits.SoftVID = maxvid;
-	wrmsrl (MSR_VIA_LONGHAUL, longhaul.val);
-
-	minvid = voltage_table[minvid];
-	maxvid = voltage_table[maxvid];
-
-	dprintk ("Min VID=%d.%03d Max VID=%d.%03d, %d possible voltage scales\n",
-		maxvid/1000, maxvid%1000, minvid/1000, minvid%1000, numvscales);
-
 	can_scale_voltage = 1;
 }
 
@@ -685,7 +700,7 @@ static int __init longhaul_cpu_init(stru
 		return ret;
 
 	if ((longhaul_version==TYPE_LONGHAUL_V2 || longhaul_version==TYPE_POWERSAVER) &&
-		 (dont_scale_voltage==0))
+		 (scale_voltage != 0))
 		longhaul_setup_voltagescaling();
 
 	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
@@ -773,8 +788,8 @@ static void __exit longhaul_exit(void)
 	kfree(longhaul_table);
 }
 
-module_param (dont_scale_voltage, int, 0644);
-MODULE_PARM_DESC(dont_scale_voltage, "Don't scale voltage of processor");
+module_param (scale_voltage, int, 0644);
+MODULE_PARM_DESC(scale_voltage, "Scale voltage of processor");
 module_param(ignore_latency, int, 0644);
 MODULE_PARM_DESC(ignore_latency, "Skip ACPI C3 latency test");
 
diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.h b/arch/i386/kernel/cpu/cpufreq/longhaul.h
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.h
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.h
@@ -450,17 +450,45 @@ static int __initdata nehemiah_c_eblcr[3
  * Voltage scales. Div/Mod by 1000 to get actual voltage.
  * Which scale to use depends on the VRM type in use.
  */
-static int __initdata vrm85scales[32] = {
-	1250, 1200, 1150, 1100, 1050, 1800, 1750, 1700,
-	1650, 1600, 1550, 1500, 1450, 1400, 1350, 1300,
-	1275, 1225, 1175, 1125, 1075, 1825, 1775, 1725,
-	1675, 1625, 1575, 1525, 1475, 1425, 1375, 1325,
+
+struct mV_pos {
+	unsigned short mV;
+	unsigned short pos;
+};
+
+static struct mV_pos __initdata vrm85_mV[32] = {
+	{1250, 8},	{1200, 6},	{1150, 4},	{1100, 2},
+	{1050, 0},	{1800, 30},	{1750, 28},	{1700, 26},
+	{1650, 24},	{1600, 22},	{1550, 20},	{1500, 18},
+	{1450, 16},	{1400, 14},	{1350, 12},	{1300, 10},
+	{1275, 9},	{1225, 7},	{1175, 5},	{1125, 3},
+	{1075, 1},	{1825, 31},	{1775, 29},	{1725, 27},
+	{1675, 25},	{1625, 23},	{1575, 21},	{1525, 19},
+	{1475, 17},	{1425, 15},	{1375, 13},	{1325, 11}
+};
+
+static unsigned char __initdata mV_vrm85[32] = {
+	0x04,	0x14,	0x03,	0x13,	0x02,	0x12,	0x01,	0x11,
+	0x00,	0x10,	0x0f,	0x1f,	0x0e,	0x1e,	0x0d,	0x1d,
+	0x0c,	0x1c,	0x0b,	0x1b,	0x0a,	0x1a,	0x09,	0x19,
+	0x08,	0x18,	0x07,	0x17,	0x06,	0x16,	0x05,	0x15
+};
+
+static struct mV_pos __initdata mobilevrm_mV[32] = {
+	{1750, 31},	{1700, 30},	{1650, 29},	{1600, 28},
+	{1550, 27},	{1500, 26},	{1450, 25},	{1400, 24},
+	{1350, 23},	{1300, 22},	{1250, 21},	{1200, 20},
+	{1150, 19},	{1100, 18},	{1050, 17},	{1000, 16},
+	{975, 15},	{950, 14},	{925, 13},	{900, 12},
+	{875, 11},	{850, 10},	{825, 9},	{800, 8},
+	{775, 7},	{750, 6},	{725, 5},	{700, 4},
+	{675, 3},	{650, 2},	{625, 1},	{600, 0}
 };
 
-static int __initdata mobilevrmscales[32] = {
-	2000, 1950, 1900, 1850, 1800, 1750, 1700, 1650,
-	1600, 1550, 1500, 1450, 1500, 1350, 1300, -1,
-	1275, 1250, 1225, 1200, 1175, 1150, 1125, 1100,
-	1075, 1050, 1025, 1000, 975, 950, 925, -1,
+static unsigned char __initdata mV_mobilevrm[32] = {
+	0x1f,	0x1e,	0x1d,	0x1c,	0x1b,	0x1a,	0x19,	0x18,
+	0x17,	0x16,	0x15,	0x14,	0x13,	0x12,	0x11,	0x10,
+	0x0f,	0x0e,	0x0d,	0x0c,	0x0b,	0x0a,	0x09,	0x08,
+	0x07,	0x06,	0x05,	0x04,	0x03,	0x02,	0x01,	0x00
 };