This is based on the old code on arch/x86/kernel/mfgpt_32.c, except it's

not x86 specific, it's modular, and it makes use of a PCI BAR rather than
a random MSR.  Currently module unloading is not supported; it's uncertain
whether or not it can be made work with the hardware.
Signed-off-by: Andres Salomon <dilinger@collabora.co.uk>
Cc: Jordan Crouse <jordan@cosmicpenguin.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Chris Ball <cjb@laptop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/x86/include/asm/geode.h

@@ -47,16 +47,6 @@ extern int geode_get_dev_base(unsigned int dev);
 
 #define MSR_DIVIL_SOFT_RESET	0x51400017
 
-#define MSR_PIC_YSEL_LOW	0x51400020
-#define MSR_PIC_YSEL_HIGH	0x51400021
-#define MSR_PIC_ZSEL_LOW	0x51400022
-#define MSR_PIC_ZSEL_HIGH	0x51400023
-#define MSR_PIC_IRQM_LPC	0x51400025
-
-#define MSR_MFGPT_IRQ		0x51400028
-#define MSR_MFGPT_NR		0x51400029
-#define MSR_MFGPT_SETUP		0x5140002B
-
 #define MSR_LX_SPARE_MSR	0x80000011	/* DC-specific */
 
 #define MSR_GX_GLD_MSR_CONFIG	0xC0002001
@@ -169,36 +159,6 @@ static inline int geode_has_vsa2(void)
 }
 #endif
 
-/* MFGPTs */
-
-#define MFGPT_MAX_TIMERS	8
-#define MFGPT_TIMER_ANY		(-1)
-
-#define MFGPT_DOMAIN_WORKING	1
-#define MFGPT_DOMAIN_STANDBY	2
-#define MFGPT_DOMAIN_ANY	(MFGPT_DOMAIN_WORKING | MFGPT_DOMAIN_STANDBY)
-
-#define MFGPT_CMP1		0
-#define MFGPT_CMP2		1
-
-#define MFGPT_EVENT_IRQ		0
-#define MFGPT_EVENT_NMI		1
-#define MFGPT_EVENT_RESET	3
-
-#define MFGPT_REG_CMP1		0
-#define MFGPT_REG_CMP2		2
-#define MFGPT_REG_COUNTER	4
-#define MFGPT_REG_SETUP		6
-
-#define MFGPT_SETUP_CNTEN	(1 << 15)
-#define MFGPT_SETUP_CMP2	(1 << 14)
-#define MFGPT_SETUP_CMP1	(1 << 13)
-#define MFGPT_SETUP_SETUP	(1 << 12)
-#define MFGPT_SETUP_STOPEN	(1 << 11)
-#define MFGPT_SETUP_EXTEN	(1 << 10)
-#define MFGPT_SETUP_REVEN	(1 << 5)
-#define MFGPT_SETUP_CLKSEL	(1 << 4)
-
 static inline void geode_mfgpt_write(int timer, u16 reg, u16 value)
 {
 	u32 base = geode_get_dev_base(GEODE_DEV_MFGPT);

drivers/misc/Kconfig

@@ -215,6 +215,29 @@ config SGI_XP
 	  this feature will allow for direct communication between SSIs
 	  based on a network adapter and DMA messaging.
 
+config CS5535_MFGPT
+	tristate "CS5535/CS5536 Geode Multi-Function General Purpose Timer (MFGPT) support"
+	depends on PCI && !MGEODE_LX
+	default n
+	help
+	  This driver provides access to MFGPT functionality for other
+	  drivers that need timers.  MFGPTs are available in the CS5535 and
+	  CS5536 companion chips that are found in AMD Geode and several
+	  other platforms.  They have a better resolution and max interval
+	  than the generic PIT, and are suitable for use as high-res timers.
+	  You probably don't want to enable this manually; other drivers that
+	  make use of it should enable it.
+
+config CS5535_MFGPT_DEFAULT_IRQ
+	int
+	default 7
+	help
+	  MFGPTs on the CS5535 require an interrupt.  The selected IRQ
+	  can be overridden as a module option as well as by driver that
+	  use the cs5535_mfgpt_ API; however, different architectures might
+	  want to use a different IRQ by default.  This is here for
+	  architectures to set as necessary.
+
 config HP_ILO
 	tristate "Channel interface driver for HP iLO/iLO2 processor"
 	depends on PCI

drivers/misc/Makefile

@@ -18,6 +18,7 @@ obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
 obj-$(CONFIG_KGDB_TESTS)	+= kgdbts.o
 obj-$(CONFIG_SGI_XP)		+= sgi-xp/
 obj-$(CONFIG_SGI_GRU)		+= sgi-gru/
+obj-$(CONFIG_CS5535_MFGPT)	+= cs5535-mfgpt.o
 obj-$(CONFIG_HP_ILO)		+= hpilo.o
 obj-$(CONFIG_ISL29003)		+= isl29003.o
 obj-$(CONFIG_EP93XX_PWM)	+= ep93xx_pwm.o

include/linux/cs5535.h

@@ -18,6 +18,16 @@
 #define MSR_LBAR_ACPI		0x5140000E
 #define MSR_LBAR_PMS		0x5140000F
 
+#define MSR_PIC_YSEL_LOW	0x51400020
+#define MSR_PIC_YSEL_HIGH	0x51400021
+#define MSR_PIC_ZSEL_LOW	0x51400022
+#define MSR_PIC_ZSEL_HIGH	0x51400023
+#define MSR_PIC_IRQM_LPC	0x51400025
+
+#define MSR_MFGPT_IRQ		0x51400028
+#define MSR_MFGPT_NR		0x51400029
+#define MSR_MFGPT_SETUP		0x5140002B
+
 /* resource sizes */
 #define LBAR_GPIO_SIZE		0xFF
 #define LBAR_MFGPT_SIZE		0x40
@@ -55,4 +65,61 @@ void cs5535_gpio_set(unsigned offset, unsigned int reg);
 void cs5535_gpio_clear(unsigned offset, unsigned int reg);
 int cs5535_gpio_isset(unsigned offset, unsigned int reg);
 
+/* MFGPTs */
+
+#define MFGPT_MAX_TIMERS	8
+#define MFGPT_TIMER_ANY		(-1)
+
+#define MFGPT_DOMAIN_WORKING	1
+#define MFGPT_DOMAIN_STANDBY	2
+#define MFGPT_DOMAIN_ANY	(MFGPT_DOMAIN_WORKING | MFGPT_DOMAIN_STANDBY)
+
+#define MFGPT_CMP1		0
+#define MFGPT_CMP2		1
+
+#define MFGPT_EVENT_IRQ		0
+#define MFGPT_EVENT_NMI		1
+#define MFGPT_EVENT_RESET	3
+
+#define MFGPT_REG_CMP1		0
+#define MFGPT_REG_CMP2		2
+#define MFGPT_REG_COUNTER	4
+#define MFGPT_REG_SETUP		6
+
+#define MFGPT_SETUP_CNTEN	(1 << 15)
+#define MFGPT_SETUP_CMP2	(1 << 14)
+#define MFGPT_SETUP_CMP1	(1 << 13)
+#define MFGPT_SETUP_SETUP	(1 << 12)
+#define MFGPT_SETUP_STOPEN	(1 << 11)
+#define MFGPT_SETUP_EXTEN	(1 << 10)
+#define MFGPT_SETUP_REVEN	(1 << 5)
+#define MFGPT_SETUP_CLKSEL	(1 << 4)
+
+struct cs5535_mfgpt_timer;
+
+extern uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer,
+		uint16_t reg);
+extern void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
+		uint16_t value);
+
+extern int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
+		int event, int enable);
+extern int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp,
+		int *irq, int enable);
+extern struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer,
+		int domain);
+extern void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer);
+
+static inline int cs5535_mfgpt_setup_irq(struct cs5535_mfgpt_timer *timer,
+		int cmp, int *irq)
+{
+	return cs5535_mfgpt_set_irq(timer, cmp, irq, 1);
+}
+
+static inline int cs5535_mfgpt_release_irq(struct cs5535_mfgpt_timer *timer,
+		int cmp, int *irq)
+{
+	return cs5535_mfgpt_set_irq(timer, cmp, irq, 0);
+}
+
 #endif