amd76x_pm: C2 powersaving for AMD K7

diff -Nru linux-2.6.14/Documentation/amd76x_pm.txt linux-2.6.14-jo/Documentation/amd76x_pm.txt
@@ -0,0 +1,341 @@
+	ACPI style power management for SMP AMD-760MP(X) based systems
+	==============================================================
+
+For use until the ACPI project catches up. :-)
+
+Using this module saves about 70 - 90W of energy in the idle mode compared
+to the default idle mode. Waking up from the idle mode is fast to keep the
+system response time good. Currently no CPU load calculation is done, the
+system exits the idle mode after every C2 call.
+
+Known issues:
+-------------
+- Currently there's a bug somewhere where the reading the
+  P_LVL2 for the first time causes the system to sleep instead of 
+  idling. This means that you need to hit the power button once to
+  wake the system after loading the module for the first time after
+  reboot. After that the system idles as supposed.
+  (Only observed on Tony's system.)
+
+- On kernel up to and including 2.6.13 there might appear a weird
+  keyboard repeating after an uptime of 1-2 days.  This seems to
+  coincide with IRQ 0 being routed to CPU1: setting smp_affinity to 1 for
+  IRQ 0 soon after booting circumvents the problem.  On 2.6.14 interrupt
+  routing has changed and I didn't watch the problem anymore.
+
+- There might be reduced throughput of disk or network devices.  See
+  below for how to configure the "irq rate watcher" to avoid this.
+
+- I have a report of occasional hard lockups that might be caused by
+  amd76x_pm.
+
+Influenced by Vcool, and LVCool. Rewrote everything from scratch to
+use the PCI features in Linux, and to support SMP systems.
+
+Currently tested amongst others on a TYAN S2460 (760MP) system (Tony), an
+ASUS A7M266-D (760MPX) system (Johnathan) and a TYAN S2466 (760MPX)
+system (Jo). Adding support for other Athlon SMP or single processor
+systems should be easy if desired.  
+
+The file /sys/devices/pci0000:00/0000:00:00.0/C2_cnt shows the number of
+C2 calls since module load.
+
+There are some parameters for tuning the behaviour of amd76x_pm:
+lazy_idle, spin_idle, watch_irqs, watch_int and min_C1
+
+lazy_idle and spin_idle are closely related:
+
+- lazy_idle defines the number of idle calls into amd76x_smp_idle that are
+  needed to *enable* C2 mode.  This parameter is the maximum loop counter
+  for an outer loop with interrupts enabled that guarantees low latencies. 
+  The default for lazy_idle is 512.
+
+- spin_idle defines the maximum number of spin cycles in an inner idle loop
+  where one CPU waits for all others to get into C2-enabled mode. When all
+  CPUs are in C2-enable mode they (more ore less) simultaneously *enter* C2
+  mode. In this inner loop interrupts are disabled.  The loop is left
+  immediatly if there is something waiting to be scheduled.  The default
+  for spin_idle is 2*lazy_idle.
+
+lazy_idle and spin_idle define a "rubber measure" for the idling
+behaviour: lazy_idle defines the minimum "idling" needed to enter C2 and
+spin_idle defines when to give up.
+
+Low values for lazy_idle and high values for spin_idle give better
+cooling.  Higher values for lazy_idle simply give less cooling.  spin_idle
+is a kind of emergency break to leave C2-enable mode if CPUs don't
+synchronize.
+
+irq rate watcher:
+-----------------
+Interrupts are disabled in C2 mode.  The CPUs are woken up by timer
+interrups or by NMIs.  This causes a high interrupt latency for other
+interrupts that leads to a significant reduction in io or network
+throughput.  There has been introduced a "irq rate watcher" to reduce
+this effect.  If the irq rate watcher detects that an interrupt has a
+rate above a given limit, C2 idling is disabled and a low latency C1
+idling mode is used instead. The parameters watch_irqs, watch_int and
+min_C1 control this irq rate watcher:
+
+- watch_irqs defines which interrupts are to be watched and optionally
+  at which interrupt rate C2 mode shall be disabled.  The syntax for 
+  watch_irqs is irq1[:rate1],irq2[:rate2],...  The rate is measured in
+  interrupts per second and defaults to 128.  There is no default for
+  watch_irqs.  To enable the irq rate watcher you must specify this
+  parameter.  Enter the interrupts used by disk controllers or network
+  adapters here.
+  
+- watch_int defines the time interval (in milliseconds) at which the
+  interrupt rate is checked.  Too low values may result in an overhead
+  and too high values cause the C1 mode to "kick in" later.  The default
+  for watch_int is 1 second.
+
+- min_C1 defines the mininum number of check intervals with low
+  interrupt rates that are needed to leave the forced C1 mode.
+
+All parameters lazy_idle, spin_idle, watch_irqs and watch_int may be
+given as module parameters to amd76x_pm.  Furthermore, they may be
+queried or changed via their sysfs entries in
+/sys/module/amd76x_pm/parameters.  (The file location in sysfs has
+changed from earlier versions!)
+
+Setting watch_int to zero or removing all interrupts from watch_irqs
+causes the irq rate watcher to stop.  The module needs to be reloaded to
+start the watcher again.
+
+NB: In the past there was a major impact from amd76x_pm on the system
+clock stability.  At least on my box this effect has been reduced
+noticable.  This is caused by two changes:
+
+- The redesign of the idle function lead to a reduced time spent in
+  amd76x_smp_idle() and this propably caused lower latencies.
+  
+- The introduction of the irq rate watcher significantly reduced
+  latencies under load.
+
+Some hints on tuning lazy_idle and spin_idle:
+Watch the rate of C2 calls per second.  Anything below HZ seems to be
+completely useless.  Start with a moderate low value for lazy_idle, e.g.
+2^5 and a very high value for spin_idle, e.g. 2^20.  Then double lazy_idle
+until you see a significant increase in core temperature or C2 rate. 
+Go back to the last "good" value.  Then halve spin_idle until you see
+a decrease in C2 rate or a raising core temperature again and go back
+to the previous value.  There's a small program c2rate.c attached at the
+end of this file that you may use to watch the C2 rate.  The rtc driver
+must be enabled to use it.
+
+There is an -extra patch available that adds some optional features:
+- C3 idling: this works but is not well tested.
+- normal throttling: untested for a long time.
+- Power On Suspend: very experimental and untested.
+
+This software is licensed under GNU General Public License Version 2 
+as specified in file COPYING in the Linux kernel source tree main 
+directory.
+
+Copyright (C) 2002 - 2005	Johnathan Hicks <[email protected]>
+				Tony Lindgren <[email protected]>
+				Joerg Sommrey <[email protected]>
+
+History:
+
+  20020702 - amd-smp-idle: Tony Lindgren <[email protected]>
+Influenced by Vcool, and LVCool. Rewrote everything from scratch to
+use the PCI features in Linux, and to support SMP systems. Provides
+C2 idling on SMP AMD-760MP systems.
+
+  20020722: JH
+  	I adapted Tony's code for the AMD-765/766 southbridge and adapted it
+  	according to the AMD-768 data sheet to provide the same capability for
+  	SMP AMD-760MPX systems. Posted to acpi-devel list.
+  	
+  20020722: Alan Cox
+  	Replaces non-functional amd76x_pm code in -ac tree.
+  	
+  20020730: JH
+  	Added ability to do normal throttling (the non-thermal kind), C3 idling
+  	and Power On Suspend (S1 sleep). It would be very easy to tie swsusp
+  	into activate_amd76x_SLP(). C3 idling doesn't happen yet; see my note
+  	in amd76x_smp_idle(). I've noticed that when NTH and idling are both
+  	enabled, my hardware locks and requires a hard reset, so I have
+  	#ifndefed around the idle loop setting to prevent this. POS locks it up
+  	too, both ought to be fixable. I've also noticed that idling and NTH
+  	make some interference that is picked up by the onboard sound chip on
+  	my ASUS A7M266-D motherboard.
+
+  20030601: Pasi Savolainen
+     Simple port to 2.5
+     Added sysfs interface for making nice graphs with mrtg.
+     Look for /sys/devices/pci0/00:00.0/C2_cnt & lazy_idle (latter writable)
+
+  20050601: Joerg Sommrey (jo)
+     2.6 stuff
+     redesigned amd76x_smp_idle.  The algorithm is basically the same
+        but the implementation has changed.  This part is now independent
+        from the number of CPUs and data is locked against concurrent
+        updates from different CPUs.
+     use _smp_processor_id()
+     use cpu_idle_wait()
+     NTH and POS code not touched and not tested.
+
+  20050621: jo
+     separated C3, NTH and POS code into extra patch
+
+  20050812: jo
+     rewritten amd76x_smp_idle completely. It's much simpler now but
+     does a good job - the KISS approach.  Introduced a new tunable
+     spin_idle.
+
+  20050819: jo
+     new irq rate watcher task that forces C1-idling if irq-rate exceeds a
+     given limit.
+
+  20050820: jo
+     make all modules parameters r/w in sysfs.
+
+  20050906: jo
+     avoid some local_irq_disable/enable
+  
+TODO: Thermal throttling (TTH).
+	 /proc interface for normal throttling level.
+	 /proc interface for POS.
+
+---- c2rate.c ---- snip here ----------------------------------------
+/* c2rate.c
+ * usage: c2rate [interval]
+ * interval is the time in seconds between two calculations and defaults
+ * to 16
+ * You may #define C3 if you're playing with C3 mode.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <linux/rtc.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define C2_CNT "/sys/devices/pci0000:00/0000:00:00.0/C2_cnt"
+#define C3_CNT "/sys/devices/pci0000:00/0000:00:00.0/C3_cnt"
+// #define C3
+int fd;
+
+void
+disable_rtc(void) {
+	int retval;
+	/* Disable alarm interrupts */
+	retval = ioctl(fd, RTC_UIE_OFF, 0);
+	if (retval == -1) {
+		perror("ioctl(RTC_UIE_OFF)");
+		_exit(errno);
+	}
+	close(fd);
+}
+
+int
+main(int argc, char **argv)
+{
+	int retval;
+	unsigned long data;
+	char idlebuffer[64];
+	int idlefd;
+	ssize_t bytes;
+	unsigned long  lastcount;
+	unsigned long  irqcount;
+	unsigned long c2_old, c2_new;
+#ifdef C3
+	unsigned long c3_old, c3_new;
+#endif
+	int rate = 0;
+	int firstloop = 1;
+
+	if(argc > 1)
+		rate = atoi(argv[1]);
+	if (rate <= 0)
+		rate = 16;
+
+	fd = open ("/dev/rtc", O_RDONLY);
+
+	if (fd ==  -1) {
+		perror("/dev/rtc");
+		exit(errno);
+	}
+
+	/* Set the alarm to every second */
+
+	retval = ioctl(fd, RTC_UIE_ON, 0);
+	if (retval == -1) {
+		perror("ioctl(RTC_UIE_ON)");
+		exit(errno);
+	}
+	atexit(disable_rtc);
+
+	irqcount = 0;
+	while (1) {
+		/* This blocks until the alarm ring causes an interrupt */
+		retval = read(fd, &data, sizeof data);
+		if (retval == -1) {
+			perror("read");
+			exit(errno);
+		}
+		if (firstloop) {
+			idlebuffer[0] = '\0';
+			idlefd = open(C2_CNT, O_RDONLY);
+			if (idlefd != -1) {
+				bytes = read(idlefd, idlebuffer, sizeof idlebuffer);
+				close(idlefd);
+				idlebuffer[bytes] = '\0';
+			}
+			c2_old = strtoul(idlebuffer, NULL, 10);
+#ifdef C3
+			idlebuffer[0] = '\0';
+			idlefd = open(C3_CNT, O_RDONLY);
+			if (idlefd != -1) {
+				bytes = read(idlefd, idlebuffer, sizeof idlebuffer);
+				close(idlefd);
+				idlebuffer[bytes] = '\0';
+			}
+			c3_old = strtoul(idlebuffer, NULL, 10);
+#endif
+			firstloop = 0;
+			continue;
+		}
+		lastcount = data >> 8;
+		irqcount += lastcount;
+
+		if (irqcount >= rate) {
+			idlebuffer[0] = '\0';
+			idlefd = open(C2_CNT, O_RDONLY);
+			if (idlefd != -1) {
+				bytes = read(idlefd, idlebuffer, sizeof idlebuffer);
+				close(idlefd);
+				idlebuffer[bytes] = '\0';
+			}
+			c2_new = strtoul(idlebuffer, NULL, 10);
+#ifdef C3
+			idlebuffer[0] = '\0';
+			idlefd = open(C3_CNT, O_RDONLY);
+			if (idlefd != -1) {
+				bytes = read(idlefd, idlebuffer, sizeof idlebuffer);
+				close(idlefd);
+				idlebuffer[bytes] = '\0';
+			}
+			c3_new = strtoul(idlebuffer, NULL, 10);
+			printf("%lu\t%lu\n", (c2_new - c2_old) / irqcount,
+					(c3_new - c3_old) / irqcount);
+			c3_old = c3_new;
+#else
+			printf("%lu\n", (c2_new - c2_old) / irqcount);
+#endif
+			c2_old = c2_new;
+			irqcount = 0;
+		}
+
+	}
+	
+	return 0;
+
+} /* end main */
+---- c2rate.c ---- snip here ----------------------------------------

diff -Nru linux-2.6.14/drivers/acpi/Kconfig linux-2.6.14-jo/drivers/acpi/Kconfig
@@ -341,4 +341,18 @@
 		$>modprobe acpi_memhotplug 
 endif	# ACPI
 
+config AMD76X_PM
+        tristate "AMD76x Native Power Management support"
+        default n
+        depends on X86 && PCI
+        ---help---
+          This driver enables Power Management on AMD760MP & AMD760MPX chipsets.          This is about same as ACPI C2, except that ACPI folks don't do SMP ATM.
+          See Documentation/amd76x_pm.txt for further details.
+
+          To compile this driver as a module ( = code which can be inserted in
+          and removed from the running kernel whenever you want), say M
+          here.  The module will be called amd76x_pm.
+
+          If unsure, say N.
+
 endmenu

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diff -Nru linux-2.6.14/drivers/acpi/Makefile linux-2.6.14-jo/drivers/acpi/Makefile
@@ -57,3 +57,8 @@
 obj-$(CONFIG_ACPI_TOSHIBA)	+= toshiba_acpi.o
 obj-y				+= scan.o motherboard.o
 obj-$(CONFIG_ACPI_HOTPLUG_MEMORY)	+= acpi_memhotplug.o
+
+#
+# not really ACPI thing, until they handle SMP.
+#
+obj-$(CONFIG_AMD76X_PM)               += amd76x_pm.o

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