MIPS: Add new GIC clockevent driver.

Add new clockevent driver that uses the counter present on the MIPS
Global Interrupt Controller.
Signed-off-by: Raghu Gandham <Raghu.Gandham@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

arch/mips/Kconfig

@@ -912,6 +912,9 @@ config CEVT_GT641XX
 config CEVT_R4K
 	bool
 
+config CEVT_GIC
+	bool
+
 config CEVT_SB1250
 	bool
 
@@ -1819,6 +1822,15 @@ config FORCE_MAX_ZONEORDER
 	  The page size is not necessarily 4KB.  Keep this in mind
 	  when choosing a value for this option.
 
+config CEVT_GIC
+	bool "Use GIC global counter for clock events"
+	depends on IRQ_GIC && !(MIPS_SEAD3 || MIPS_MT_SMTC)
+	help
+	  Use the GIC global counter for the clock events. The R4K clock
+	  event driver is always present, so if the platform ends up not
+	  detecting a GIC, it will fall back to the R4K timer for the
+	  generation of clock events.
+
 config BOARD_SCACHE
 	bool
 

arch/mips/include/asm/gic.h

@@ -202,7 +202,7 @@
 #define GIC_VPE_WD_COUNT0_OFS		0x0094
 #define GIC_VPE_WD_INITIAL0_OFS		0x0098
 #define GIC_VPE_COMPARE_LO_OFS		0x00a0
-#define GIC_VPE_COMPARE_HI		0x00a4
+#define GIC_VPE_COMPARE_HI_OFS		0x00a4
 
 #define GIC_VPE_EIC_SHADOW_SET_BASE	0x0100
 #define GIC_VPE_EIC_SS(intr) \
@@ -373,7 +373,10 @@ extern void gic_init(unsigned long gic_base_addr,
 	unsigned long gic_addrspace_size, struct gic_intr_map *intrmap,
 	unsigned int intrmap_size, unsigned int irqbase);
 extern void gic_clocksource_init(unsigned int);
+extern unsigned int gic_compare_int (void);
 extern cycle_t gic_read_count(void);
+extern cycle_t gic_read_compare(void);
+extern void gic_write_compare(cycle_t cnt);
 extern void gic_send_ipi(unsigned int intr);
 extern unsigned int plat_ipi_call_int_xlate(unsigned int);
 extern unsigned int plat_ipi_resched_int_xlate(unsigned int);

arch/mips/include/asm/time.h

@@ -53,11 +53,14 @@ extern int (*perf_irq)(void);
 extern unsigned int __weak get_c0_compare_int(void);
 extern int r4k_clockevent_init(void);
 extern int smtc_clockevent_init(void);
+extern int gic_clockevent_init(void);
 
 static inline int mips_clockevent_init(void)
 {
 #ifdef CONFIG_MIPS_MT_SMTC
 	return smtc_clockevent_init();
+#elif defined(CONFIG_CEVT_GIC)
+	return (gic_clockevent_init() | r4k_clockevent_init());
 #elif defined(CONFIG_CEVT_R4K)
 	return r4k_clockevent_init();
 #else

arch/mips/kernel/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_CEVT_BCM1480)	+= cevt-bcm1480.o
 obj-$(CONFIG_CEVT_R4K)		+= cevt-r4k.o
 obj-$(CONFIG_MIPS_MT_SMTC)	+= cevt-smtc.o
 obj-$(CONFIG_CEVT_DS1287)	+= cevt-ds1287.o
+obj-$(CONFIG_CEVT_GIC)		+= cevt-gic.o
 obj-$(CONFIG_CEVT_GT641XX)	+= cevt-gt641xx.o
 obj-$(CONFIG_CEVT_SB1250)	+= cevt-sb1250.o
 obj-$(CONFIG_CEVT_TXX9)		+= cevt-txx9.o

arch/mips/kernel/cevt-gic.c

+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013  Imagination Technologies Ltd.
+ */
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+#include <linux/irq.h>
+
+#include <asm/time.h>
+#include <asm/gic.h>
+#include <asm/mips-boards/maltaint.h>
+
+DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
+int gic_timer_irq_installed;
+
+
+static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
+{
+	u64 cnt;
+	int res;
+
+	cnt = gic_read_count();
+	cnt += (u64)delta;
+	gic_write_compare(cnt);
+	res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
+	return res;
+}
+
+void gic_set_clock_mode(enum clock_event_mode mode,
+				struct clock_event_device *evt)
+{
+	/* Nothing to do ...  */
+}
+
+irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *cd;
+	int cpu = smp_processor_id();
+
+	gic_write_compare(gic_read_compare());
+	cd = &per_cpu(gic_clockevent_device, cpu);
+	cd->event_handler(cd);
+	return IRQ_HANDLED;
+}
+
+struct irqaction gic_compare_irqaction = {
+	.handler = gic_compare_interrupt,
+	.flags = IRQF_PERCPU | IRQF_TIMER,
+	.name = "timer",
+};
+
+
+void gic_event_handler(struct clock_event_device *dev)
+{
+}
+
+int __cpuinit gic_clockevent_init(void)
+{
+	unsigned int cpu = smp_processor_id();
+	struct clock_event_device *cd;
+	unsigned int irq;
+
+	if (!cpu_has_counter || !gic_frequency)
+		return -ENXIO;
+
+	irq = MIPS_GIC_IRQ_BASE;
+
+	cd = &per_cpu(gic_clockevent_device, cpu);
+
+	cd->name		= "MIPS GIC";
+	cd->features		= CLOCK_EVT_FEAT_ONESHOT;
+
+	clockevent_set_clock(cd, gic_frequency);
+
+	/* Calculate the min / max delta */
+	cd->max_delta_ns	= clockevent_delta2ns(0x7fffffff, cd);
+	cd->min_delta_ns	= clockevent_delta2ns(0x300, cd);
+
+	cd->rating		= 300;
+	cd->irq			= irq;
+	cd->cpumask		= cpumask_of(cpu);
+	cd->set_next_event	= gic_next_event;
+	cd->set_mode		= gic_set_clock_mode;
+	cd->event_handler	= gic_event_handler;
+
+	clockevents_register_device(cd);
+
+	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_MAP), 0x80000002);
+	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_SMASK), GIC_VPE_SMASK_CMP_MSK);
+
+	if (gic_timer_irq_installed)
+		return 0;
+
+	gic_timer_irq_installed = 1;
+
+	setup_irq(irq, &gic_compare_irqaction);
+	irq_set_handler(irq, handle_percpu_irq);
+	return 0;
+}

arch/mips/kernel/cevt-r4k.c

@@ -72,6 +72,9 @@ irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
 		/* Clear Count/Compare Interrupt */
 		write_c0_compare(read_c0_compare());
 		cd = &per_cpu(mips_clockevent_device, cpu);
+#ifdef CONFIG_CEVT_GIC
+		if (!gic_present)
+#endif
 		cd->event_handler(cd);
 	}
 
@@ -203,6 +206,9 @@ int __cpuinit r4k_clockevent_init(void)
 	cd->set_mode		= mips_set_clock_mode;
 	cd->event_handler	= mips_event_handler;
 
+#ifdef CONFIG_CEVT_GIC
+	if (!gic_present)
+#endif
 	clockevents_register_device(cd);
 
 	if (cp0_timer_irq_installed)

arch/mips/kernel/irq-gic.c

@@ -33,7 +33,7 @@ static struct gic_pcpu_mask pcpu_masks[NR_CPUS];
 static struct gic_pending_regs pending_regs[NR_CPUS];
 static struct gic_intrmask_regs intrmask_regs[NR_CPUS];
 
-#ifdef CONFIG_CSRC_GIC
+#if defined(CONFIG_CSRC_GIC) || defined(CONFIG_CEVT_GIC)
 cycle_t gic_read_count(void)
 {
 	unsigned int hi, hi2, lo;
@@ -46,6 +46,24 @@ cycle_t gic_read_count(void)
 
 	return (((cycle_t) hi) << 32) + lo;
 }
+
+void gic_write_compare(cycle_t cnt)
+{
+	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_HI),
+				(int)(cnt >> 32));
+	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_LO),
+				(int)(cnt & 0xffffffff));
+}
+
+cycle_t gic_read_compare(void)
+{
+	unsigned int hi, lo;
+
+	GICREAD(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_HI), hi);
+	GICREAD(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_LO), lo);
+
+	return (((cycle_t) hi) << 32) + lo;
+}
 #endif
 
 unsigned int gic_get_timer_pending(void)
@@ -134,6 +152,17 @@ static void __init vpe_local_setup(unsigned int numvpes)
 	}
 }
 
+unsigned int gic_compare_int(void)
+{
+	unsigned int pending;
+
+	GICREAD(GIC_REG(VPE_LOCAL, GIC_VPE_PEND), pending);
+	if (pending & GIC_VPE_PEND_CMP_MSK)
+		return 1;
+	else
+		return 0;
+}
+
 unsigned int gic_get_int(void)
 {
 	unsigned int i;

arch/mips/mti-malta/malta-int.c

@@ -133,6 +133,9 @@ static void malta_ipi_irqdispatch(void)
 {
 	int irq;
 
+	if (gic_compare_int())
+		do_IRQ(MIPS_GIC_IRQ_BASE);
+
 	irq = gic_get_int();
 	if (irq < 0)
 		return;	 /* interrupt has already been cleared */