irqchip: mips-gic: Export function to read counter width

Export the function gic_get_count_width to read the width of
the GIC global counter from GIC_SH_CONFIG.  Update the GIC
clocksource driver to use this new function.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8124/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/gic.h

@@ -370,6 +370,7 @@ extern void gic_init(unsigned long gic_base_addr,
 	unsigned int irqbase);
 extern void gic_clocksource_init(unsigned int);
 extern cycle_t gic_read_count(void);
+extern unsigned int gic_get_count_width(void);
 extern cycle_t gic_read_compare(void);
 extern void gic_write_compare(cycle_t cnt);
 extern void gic_write_cpu_compare(cycle_t cnt, int cpu);

arch/mips/kernel/csrc-gic.c

@@ -23,15 +23,8 @@ static struct clocksource gic_clocksource = {
 
 void __init gic_clocksource_init(unsigned int frequency)
 {
-	unsigned int config, bits;
-
-	/* Calculate the clocksource mask. */
-	GICREAD(GIC_REG(SHARED, GIC_SH_CONFIG), config);
-	bits = 32 + ((config & GIC_SH_CONFIG_COUNTBITS_MSK) >>
-		(GIC_SH_CONFIG_COUNTBITS_SHF - 2));
-
 	/* Set clocksource mask. */
-	gic_clocksource.mask = CLOCKSOURCE_MASK(bits);
+	gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
 
 	/* Calculate a somewhat reasonable rating value. */
 	gic_clocksource.rating = 200 + frequency / 10000000;

drivers/irqchip/irq-mips-gic.c

@@ -63,6 +63,17 @@ cycle_t gic_read_count(void)
 	return (((cycle_t) hi) << 32) + lo;
 }
 
+unsigned int gic_get_count_width(void)
+{
+	unsigned int bits, config;
+
+	GICREAD(GIC_REG(SHARED, GIC_SH_CONFIG), config);
+	bits = 32 + 4 * ((config & GIC_SH_CONFIG_COUNTBITS_MSK) >>
+			 GIC_SH_CONFIG_COUNTBITS_SHF);
+
+	return bits;
+}
+
 void gic_write_compare(cycle_t cnt)
 {
 	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_HI),