linux-kernel - [PATCH 1/3] irqchip: irq-mips-gic: Add new functions to start/stop the GIC counter

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Date:	Mon, 23 Mar 2015 12:32:01 +0000
From:	Markos Chandras <markos.chandras@...tec.com>
To:	<linux-mips@...ux-mips.org>
CC:	Markos Chandras <markos.chandras@...tec.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Andrew Bresticker <abrestic@...omium.org>,
	Qais Yousef <qais.yousef@...tec.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 1/3] irqchip: irq-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@...utronix.de>
Cc: Jason Cooper <jason@...edaemon.net>
Cc: Andrew Bresticker <abrestic@...omium.org>
Cc: Qais Yousef <qais.yousef@...tec.com>
Cc: <linux-kernel@...r.kernel.org>
Signed-off-by: Markos Chandras <markos.chandras@...tec.com>
---
 drivers/irqchip/irq-mips-gic.c   | 21 +++++++++++++++++++++
 include/linux/irqchip/mips-gic.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 9acdc080e7ec..f2d269bca789 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/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)
diff --git a/include/linux/irqchip/mips-gic.h b/include/linux/irqchip/mips-gic.h
index e6a6aac451db..3ea2e4754c40 100644
--- a/include/linux/irqchip/mips-gic.h
+++ b/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);
-- 
2.3.3

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