Merge branch 'clocksource/physical-timers' into next/dt

These are a pre-req to get rk3288 SMP to work with some firmwares, so merge
it in here as well as in next/drivers.

* clocksource/physical-timers:
  clocksource: arch_timer: Allow the device tree to specify uninitialized timer registers
  clocksource: arch_timer: Fix code to use physical timers when requested

Documentation/devicetree/bindings/arm/arch_timer.txt

@@ -22,6 +22,14 @@ to deliver its interrupts via SPIs.
 - always-on : a boolean property. If present, the timer is powered through an
   always-on power domain, therefore it never loses context.
 
+** Optional properties:
+
+- arm,cpu-registers-not-fw-configured : Firmware does not initialize
+  any of the generic timer CPU registers, which contain their
+  architecturally-defined reset values. Only supported for 32-bit
+  systems which follow the ARMv7 architected reset values.
+
+
 Example:
 
 	timer {

arch/arm/include/asm/arch_timer.h

@@ -78,6 +78,15 @@ static inline u32 arch_timer_get_cntfrq(void)
 	return val;
 }
 
+static inline u64 arch_counter_get_cntpct(void)
+{
+	u64 cval;
+
+	isb();
+	asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval));
+	return cval;
+}
+
 static inline u64 arch_counter_get_cntvct(void)
 {
 	u64 cval;

arch/arm64/include/asm/arch_timer.h

@@ -104,6 +104,15 @@ static inline void arch_timer_set_cntkctl(u32 cntkctl)
 	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
 }
 
+static inline u64 arch_counter_get_cntpct(void)
+{
+	/*
+	 * AArch64 kernel and user space mandate the use of CNTVCT.
+	 */
+	BUG();
+	return 0;
+}
+
 static inline u64 arch_counter_get_cntvct(void)
 {
 	u64 cval;

drivers/clocksource/arm_arch_timer.c

@@ -462,7 +462,10 @@ static void __init arch_counter_register(unsigned type)
 
 	/* Register the CP15 based counter if we have one */
 	if (type & ARCH_CP15_TIMER) {
-		arch_timer_read_counter = arch_counter_get_cntvct;
+		if (arch_timer_use_virtual)
+			arch_timer_read_counter = arch_counter_get_cntvct;
+		else
+			arch_timer_read_counter = arch_counter_get_cntpct;
 	} else {
 		arch_timer_read_counter = arch_counter_get_cntvct_mem;
 
@@ -701,6 +704,14 @@ static void __init arch_timer_init(struct device_node *np)
 		arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
 	arch_timer_detect_rate(NULL, np);
 
+	/*
+	 * If we cannot rely on firmware initializing the timer registers then
+	 * we should use the physical timers instead.
+	 */
+	if (IS_ENABLED(CONFIG_ARM) &&
+	    of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
+			arch_timer_use_virtual = false;
+
 	/*
 	 * If HYP mode is available, we know that the physical timer
 	 * has been configured to be accessible from PL1. Use it, so