clocksource: arm_arch_timer: refactor arch_timer_needs_probing

When booting with DT, it's possible for timer nodes to be probed in any
order. Some common initialisation needs to occur after all nodes have
been probed, and arch_timer_common_init() has code to detect when this
has happened.

This logic is DT-specific, and it would be best to factor it out of the
common code that will be shared with ACPI.

This patch folds this into the existing arch_timer_needs_probing(),
which is renamed to arch_timer_needs_of_probing(), and no longer takes
any arguments. This is only called when using DT, and not when using
ACPI, which will have a deterministic probe order.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
[Mark: reword commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>

1 files changed, 19 insertions, 15 deletions

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 02c5cb86ca83..e38f4d4290ad 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1076,15 +1076,28 @@ static const struct of_device_id arch_timer_mem_of_match[] __initconst = {
         {},
 };
 
-static bool __init
-arch_timer_needs_probing(int type, const struct of_device_id *matches)
+static bool __init arch_timer_needs_of_probing(void)
 {
         struct device_node *dn;
         bool needs_probing = false;
+        unsigned int mask = ARCH_TIMER_TYPE_CP15 | ARCH_TIMER_TYPE_MEM;
 
-        dn = of_find_matching_node(NULL, matches);
-        if (dn && of_device_is_available(dn) && !(arch_timers_present & type))
+        /* We have two timers, and both device-tree nodes are probed. */
+        if ((arch_timers_present & mask) == mask)
+                return false;
+
+        /*
+         * Only one type of timer is probed,
+         * check if we have another type of timer node in device-tree.
+         */
+        if (arch_timers_present & ARCH_TIMER_TYPE_CP15)
+                dn = of_find_matching_node(NULL, arch_timer_mem_of_match);
+        else
+                dn = of_find_matching_node(NULL, arch_timer_of_match);
+
+        if (dn && of_device_is_available(dn))
                 needs_probing = true;
+
         of_node_put(dn);
 
         return needs_probing;
@@ -1092,17 +1105,8 @@ arch_timer_needs_probing(int type, const struct of_device_id *matches)
 
 static int __init arch_timer_common_init(void)
 {
-        unsigned mask = ARCH_TIMER_TYPE_CP15 | ARCH_TIMER_TYPE_MEM;
-
-        /* Wait until both nodes are probed if we have two timers */
-        if ((arch_timers_present & mask) != mask) {
-                if (arch_timer_needs_probing(ARCH_TIMER_TYPE_MEM,
-                                             arch_timer_mem_of_match))
-                        return 0;
-                if (arch_timer_needs_probing(ARCH_TIMER_TYPE_CP15,
-                                             arch_timer_of_match))
-                        return 0;
-        }
+        if (acpi_disabled && arch_timer_needs_of_probing())
+                return 0;
 
         arch_timer_banner(arch_timers_present);
         arch_counter_register(arch_timers_present);