ARM: vexpress: TC2 use sp804 timer as sched_clock

Use SP804 timer as sched_clock instead of arch timers as work-around
until the arch timers have been fixed.

Inspired by patch from Morten Rasmussen <Morten.Rasmussen@arm.com>
with the same description but made configurable by a device tree hack,
to enable a single kernel binary to be used with multiple CoreTiles.

Signed-off-by: Jon Medhurst <tixy@linaro.org>

4 files changed, 26 insertions, 5 deletions

diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15-tc2.dts b/arch/arm/boot/dts/vexpress-v2p-ca15-tc2.dts
index 2d94277251b2..958e8f710c1a 100644
--- a/arch/arm/boot/dts/vexpress-v2p-ca15-tc2.dts
+++ b/arch/arm/boot/dts/vexpress-v2p-ca15-tc2.dts
@@ -211,6 +211,7 @@
 			     <1 14 0xf08>,
 			     <1 11 0xf08>,
 			     <1 10 0xf08>;
+		broken-for-sched-clock = <1>;
 	};
 
 	pmu {
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 62e75475e57e..beceba4de355 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -7,6 +7,7 @@
 #define ARCH_HAS_READ_CURRENT_TIMER
 int arch_timer_of_register(void);
 int arch_timer_sched_clock_init(void);
+bool arch_timer_broken_for_sched_clock(void);
 #else
 static inline int arch_timer_of_register(void)
 {
@@ -17,6 +18,10 @@ static inline int arch_timer_sched_clock_init(void)
 {
 	return -ENXIO;
 }
+static inline  bool arch_timer_broken_for_sched_clock(void)
+{
+	return false;
+}
 #endif
 
 #endif
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index cf258807160d..16fd0fd122af 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -325,6 +325,16 @@ static const struct of_device_id arch_timer_of_match[] __initconst = {
 	{},
 };
 
+bool __init arch_timer_broken_for_sched_clock(void)
+{
+	u32 broken = false;
+	struct device_node *np;
+	np = of_find_matching_node(NULL, arch_timer_of_match);
+	if (np)
+		of_property_read_u32(np, "broken-for-sched-clock", &broken);
+	return broken;
+}
+
 int __init arch_timer_of_register(void)
 {
 	struct device_node *np;
diff --git a/arch/arm/mach-vexpress/v2m.c b/arch/arm/mach-vexpress/v2m.c
index 37608f22ee31..7732d8b795fb 100644
--- a/arch/arm/mach-vexpress/v2m.c
+++ b/arch/arm/mach-vexpress/v2m.c
@@ -72,7 +72,8 @@ static void __init v2m_sysctl_init(void __iomem *base)
 	writel(scctrl, base + SCCTRL);
 }
 
-static void __init v2m_sp804_init(void __iomem *base, unsigned int irq)
+static void __init v2m_sp804_init(void __iomem *base, unsigned int irq,
+				  int use_sched_clock)
 {
 	if (WARN_ON(!base || irq == NO_IRQ))
 		return;
@@ -80,7 +81,10 @@ static void __init v2m_sp804_init(void __iomem *base, unsigned int irq)
 	writel(0, base + TIMER_1_BASE + TIMER_CTRL);
 	writel(0, base + TIMER_2_BASE + TIMER_CTRL);
 
-	sp804_clocksource_init(base + TIMER_2_BASE, "v2m-timer1");
+	if (use_sched_clock)
+		sp804_clocksource_and_sched_clock_init(base + TIMER_2_BASE, "v2m-timer1");
+	else
+		sp804_clocksource_init(base + TIMER_2_BASE, "v2m-timer1");
 	sp804_clockevents_init(base + TIMER_1_BASE, irq, "v2m-timer0");
 }
 
@@ -440,7 +444,7 @@ static void __init v2m_timer_init(void)
 {
 	v2m_sysctl_init(ioremap(V2M_SYSCTL, SZ_4K));
 	v2m_clk_init();
-	v2m_sp804_init(ioremap(V2M_TIMER01, SZ_4K), IRQ_V2M_TIMER0);
+	v2m_sp804_init(ioremap(V2M_TIMER01, SZ_4K), IRQ_V2M_TIMER0, 0);
 }
 
 static struct sys_timer v2m_timer = {
@@ -612,6 +616,7 @@ static void __init v2m_dt_init_irq(void)
 
 static void __init v2m_dt_timer_init(void)
 {
+	int sp804_sched_clock = arch_timer_broken_for_sched_clock();
 	struct device_node *node;
 	const char *path;
 	int err;
@@ -625,11 +630,11 @@ static void __init v2m_dt_timer_init(void)
 	if (WARN_ON(err))
 		return;
 	node = of_find_node_by_path(path);
-	v2m_sp804_init(of_iomap(node, 0), irq_of_parse_and_map(node, 0));
+	v2m_sp804_init(of_iomap(node, 0), irq_of_parse_and_map(node, 0), sp804_sched_clock);
 	if (arch_timer_of_register() != 0)
 		twd_local_timer_of_register();
 
-	if (arch_timer_sched_clock_init() != 0)
+	if (!sp804_sched_clock && arch_timer_sched_clock_init() != 0)
 		versatile_sched_clock_init(v2m_sysreg_base + V2M_SYS_24MHZ, 24000000);
 }