i7300_idle driver v1.55

The Intel 7300 Memory Controller supports dynamic throttling of memory which can
be used to save power when system is idle. This driver does the memory
throttling when all CPUs are idle on such a system.

Refer to "Intel 7300 Memory Controller Hub (MCH)" datasheet
for the config space description.

Signed-off-by: Andy Henroid <[email protected]>
Signed-off-by: Len Brown <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>

Author: Andy Henroid

MAINTAINERS

@@ -2078,6 +2078,12 @@ L:	[email protected]
 L:	[email protected]
 S:	Orphan
 
+IDLE-I7300
+P:	Andy Henroid
+M:	[email protected]
+L:	[email protected]
+S:	Supported
+
 IEEE 1394 SUBSYSTEM (drivers/ieee1394)
 P:	Ben Collins
 M:	[email protected]

arch/x86/Kconfig

@@ -1536,6 +1536,8 @@ source "arch/x86/kernel/cpu/cpufreq/Kconfig"
 
 source "drivers/cpuidle/Kconfig"
 
+source "drivers/idle/Kconfig"
+
 endmenu
 
 

drivers/Makefile

@@ -82,6 +82,7 @@ obj-$(CONFIG_EISA)		+= eisa/
 obj-y				+= lguest/
 obj-$(CONFIG_CPU_FREQ)		+= cpufreq/
 obj-$(CONFIG_CPU_IDLE)		+= cpuidle/
+obj-y				+= idle/
 obj-$(CONFIG_MMC)		+= mmc/
 obj-$(CONFIG_MEMSTICK)		+= memstick/
 obj-$(CONFIG_NEW_LEDS)		+= leds/

drivers/dma/ioat_dma.c

@@ -171,6 +171,9 @@ static int ioat_dma_enumerate_channels(struct ioatdma_device *device)
 	xfercap_scale = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
 	xfercap = (xfercap_scale == 0 ? -1 : (1UL << xfercap_scale));
 
+#if CONFIG_I7300_IDLE_IOAT_CHANNEL
+	device->common.chancnt--;
+#endif
 	for (i = 0; i < device->common.chancnt; i++) {
 		ioat_chan = kzalloc(sizeof(*ioat_chan), GFP_KERNEL);
 		if (!ioat_chan) {

drivers/idle/Kconfig

@@ -0,0 +1,16 @@
+
+menu "Memory power savings"
+
+config I7300_IDLE_IOAT_CHANNEL
+	bool
+
+config I7300_IDLE
+	tristate "Intel chipset idle power saving driver"
+	select I7300_IDLE_IOAT_CHANNEL
+	depends on X86_64
+	help
+	  Enable idle power savings with certain Intel server chipsets.
+	  The chipset must have I/O AT support, such as the Intel 7300.
+	  The power savings depends on the type and quantity of DRAM devices.
+
+endmenu

drivers/idle/Makefile

@@ -0,0 +1,2 @@
+obj-$(CONFIG_I7300_IDLE)			+= i7300_idle.o
+