irqchip: mips-gic: Add new functions to start/stop the GIC counter

We add new functions to start and stop the GIC counter since there are no
guarantees the counter will be running after a CPU reset. The GIC counter
is stopped by setting the 29th bit on the GIC Config register and it is
started by clearing that bit.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Link: https://lkml.kernel.org/r/1427113923-9840-2-git-send-email-markos.chandras@imgtec.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-mips-gic.c

@@ -166,6 +166,27 @@ cycle_t gic_read_compare(void)
 
 	return (((cycle_t) hi) << 32) + lo;
 }
+
+void gic_start_count(void)
+{
+	u32 gicconfig;
+
+	/* Start the counter */
+	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
+	gicconfig &= ~(1 << GIC_SH_CONFIG_COUNTSTOP_SHF);
+	gic_write(GIC_REG(SHARED, GIC_SH_CONFIG), gicconfig);
+}
+
+void gic_stop_count(void)
+{
+	u32 gicconfig;
+
+	/* Stop the counter */
+	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
+	gicconfig |= 1 << GIC_SH_CONFIG_COUNTSTOP_SHF;
+	gic_write(GIC_REG(SHARED, GIC_SH_CONFIG), gicconfig);
+}
+
 #endif
 
 static bool gic_local_irq_is_routable(int intr)

include/linux/irqchip/mips-gic.h

@@ -240,6 +240,8 @@ 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);
+extern void gic_start_count(void);
+extern void gic_stop_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);