MIPS: Refactor GIC clocksource code.

Reorganize some of the GIC clocksource driver code. Below is a list of
the various changes.

  * No longer select CSRC_GIC by default for Malta platform.
  * Limit choice for either the GIC or R4K clocksource, not both.
  * Change location in Makefile.
  * Created new 'gic_read_count' function in common 'irq-gic.c' file.
  * Change 'git_hpt_read' function in 'csrc-gic.c' to use new function.
  * Surround GIC specific code in Malta platform code with #ifdef's.
  * Only initialize the GIC clocksource if it was selected. Original
    code called it unconditionally if a GIC was found.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

arch/mips/Kconfig

@@ -337,6 +337,7 @@ config MIPS_SEAD3
 	select BOOT_RAW
 	select CEVT_R4K
 	select CSRC_R4K
+	select CSRC_GIC
 	select CPU_MIPSR2_IRQ_VI
 	select CPU_MIPSR2_IRQ_EI
 	select DMA_NONCOHERENT

arch/mips/include/asm/gic.h

@@ -359,6 +359,9 @@ struct gic_shared_intr_map {
 /* Mapped interrupt to pin X, then GIC will generate the vector (X+1). */
 #define GIC_PIN_TO_VEC_OFFSET	(1)
 
+#include <linux/clocksource.h>
+#include <linux/irq.h>
+
 extern unsigned int gic_present;
 extern unsigned int gic_frequency;
 extern unsigned long _gic_base;
@@ -372,6 +375,7 @@ extern void gic_init(unsigned long gic_base_addr,
 
 extern void gic_clocksource_init(unsigned int);
 extern unsigned int gic_get_int(void);
+extern cycle_t gic_read_count(void);
 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/kernel/Makefile

@@ -23,11 +23,11 @@ obj-$(CONFIG_CEVT_GT641XX)	+= cevt-gt641xx.o
 obj-$(CONFIG_CEVT_SB1250)	+= cevt-sb1250.o
 obj-$(CONFIG_CEVT_TXX9)		+= cevt-txx9.o
 obj-$(CONFIG_CSRC_BCM1480)	+= csrc-bcm1480.o
+obj-$(CONFIG_CSRC_GIC)		+= csrc-gic.o
 obj-$(CONFIG_CSRC_IOASIC)	+= csrc-ioasic.o
 obj-$(CONFIG_CSRC_POWERTV)	+= csrc-powertv.o
 obj-$(CONFIG_CSRC_R4K)		+= csrc-r4k.o
 obj-$(CONFIG_CSRC_SB1250)	+= csrc-sb1250.o
-obj-$(CONFIG_CSRC_GIC)		+= csrc-gic.o
 obj-$(CONFIG_SYNC_R4K)		+= sync-r4k.o
 
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

arch/mips/kernel/csrc-gic.c

@@ -5,23 +5,14 @@
  *
  * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
  */
-#include <linux/clocksource.h>
 #include <linux/init.h>
+#include <linux/time.h>
 
-#include <asm/time.h>
 #include <asm/gic.h>
 
 static cycle_t gic_hpt_read(struct clocksource *cs)
 {
-	unsigned int hi, hi2, lo;
-
-	do {
-		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi);
-		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), lo);
-		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi2);
-	} while (hi2 != hi);
-
-	return (((cycle_t) hi) << 32) + lo;
+	return gic_read_count();
 }
 
 static struct clocksource gic_clocksource = {

arch/mips/kernel/irq-gic.c

@@ -10,6 +10,7 @@
 #include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/irq.h>
+#include <linux/clocksource.h>
 
 #include <asm/io.h>
 #include <asm/gic.h>
@@ -32,6 +33,21 @@ 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
+cycle_t gic_read_count(void)
+{
+	unsigned int hi, hi2, lo;
+
+	do {
+		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi);
+		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), lo);
+		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi2);
+	} while (hi2 != hi);
+
+	return (((cycle_t) hi) << 32) + lo;
+}
+#endif
+
 unsigned int gic_get_timer_pending(void)
 {
 	unsigned int vpe_pending;

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

@@ -71,7 +71,9 @@ static void __init estimate_frequencies(void)
 {
 	unsigned long flags;
 	unsigned int count, start;
+#ifdef CONFIG_IRQ_GIC
 	unsigned int giccount = 0, gicstart = 0;
+#endif
 
 	local_irq_save(flags);
 
@@ -81,26 +83,32 @@ static void __init estimate_frequencies(void)
 
 	/* Initialize counters. */
 	start = read_c0_count();
+#ifdef CONFIG_IRQ_GIC
 	if (gic_present)
 		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), gicstart);
+#endif
 
 	/* Read counter exactly on falling edge of update flag. */
 	while (CMOS_READ(RTC_REG_A) & RTC_UIP);
 	while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
 
 	count = read_c0_count();
+#ifdef CONFIG_IRQ_GIC
 	if (gic_present)
 		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), giccount);
+#endif
 
 	local_irq_restore(flags);
 
 	count -= start;
-	if (gic_present)
-		giccount -= gicstart;
-
 	mips_hpt_frequency = count;
-	if (gic_present)
+
+#ifdef CONFIG_IRQ_GIC
+	if (gic_present) {
+		giccount -= gicstart;
 		gic_frequency = giccount;
+	}
+#endif
 }
 
 void read_persistent_clock(struct timespec *ts)
@@ -156,24 +164,27 @@ void __init plat_time_init(void)
 	    (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
 		freq *= 2;
 	freq = freqround(freq, 5000);
-	pr_debug("CPU frequency %d.%02d MHz\n", freq/1000000,
+	printk("CPU frequency %d.%02d MHz\n", freq/1000000,
 	       (freq%1000000)*100/1000000);
 	cpu_khz = freq / 1000;
 
-	if (gic_present) {
-		freq = freqround(gic_frequency, 5000);
-		pr_debug("GIC frequency %d.%02d MHz\n", freq/1000000,
-		       (freq%1000000)*100/1000000);
-		gic_clocksource_init(gic_frequency);
-	} else
-		init_r4k_clocksource();
+	mips_scroll_message();
 
 #ifdef CONFIG_I8253
 	/* Only Malta has a PIT. */
 	setup_pit_timer();
 #endif
 
-	mips_scroll_message();
+#ifdef CONFIG_IRQ_GIC
+	if (gic_present) {
+		freq = freqround(gic_frequency, 5000);
+		printk("GIC frequency %d.%02d MHz\n", freq/1000000,
+		       (freq%1000000)*100/1000000);
+#ifdef CONFIG_CSRC_GIC
+		gic_clocksource_init(gic_frequency);
+#endif
+	}
+#endif
 
 	plat_perf_setup();
 }