clocksource: arm_arch_timer: add GTDT support for memory-mapped timer

The patch add memory-mapped timer register support by using the
information provided by the new GTDT driver of ACPI.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
[Mark: verify CNTFRQ, only register the first frame]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>

1 files changed, 76 insertions, 3 deletions

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index e398228d60b2..2208fa4eafee 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1386,10 +1386,79 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
                        arch_timer_mem_of_init);
 
 #ifdef CONFIG_ACPI_GTDT
-/* Initialize per-processor generic timer */
+static int __init
+arch_timer_mem_verify_cntfrq(struct arch_timer_mem *timer_mem)
+{
+        struct arch_timer_mem_frame *frame;
+        u32 rate;
+        int i;
+
+        for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
+                frame = &timer_mem->frame[i];
+
+                if (!frame->valid)
+                        continue;
+
+                rate = arch_timer_mem_frame_get_cntfrq(frame);
+                if (rate == arch_timer_rate)
+                        continue;
+
+                pr_err(FW_BUG "CNTFRQ mismatch: frame @ %pa: (0x%08lx), CPU: (0x%08lx)\n",
+                        &frame->cntbase,
+                        (unsigned long)rate, (unsigned long)arch_timer_rate);
+
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int __init arch_timer_mem_acpi_init(int platform_timer_count)
+{
+        struct arch_timer_mem *timers, *timer;
+        struct arch_timer_mem_frame *frame;
+        int timer_count, i, ret = 0;
+
+        timers = kcalloc(platform_timer_count, sizeof(*timers),
+                            GFP_KERNEL);
+        if (!timers)
+                return -ENOMEM;
+
+        ret = acpi_arch_timer_mem_init(timers, &timer_count);
+        if (ret || !timer_count)
+                goto out;
+
+        for (i = 0; i < timer_count; i++) {
+                ret = arch_timer_mem_verify_cntfrq(&timers[i]);
+                if (ret) {
+                        pr_err("Disabling MMIO timers due to CNTFRQ mismatch\n");
+                        goto out;
+                }
+        }
+
+        /*
+         * While unlikely, it's theoretically possible that none of the frames
+         * in a timer expose the combination of feature we want.
+         */
+        for (i = i; i < timer_count; i++) {
+                timer = &timers[i];
+
+                frame = arch_timer_mem_find_best_frame(timer);
+                if (frame)
+                        break;
+        }
+
+        if (frame)
+                ret = arch_timer_mem_frame_register(frame);
+out:
+        kfree(timers);
+        return ret;
+}
+
+/* Initialize per-processor generic timer and memory-mapped timer(if present) */
 static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 {
-        int ret;
+        int ret, platform_timer_count;
 
         if (arch_timers_present & ARCH_TIMER_TYPE_CP15) {
                 pr_warn("already initialized, skipping\n");
@@ -1398,7 +1467,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 
         arch_timers_present |= ARCH_TIMER_TYPE_CP15;
 
-        ret = acpi_gtdt_init(table, NULL);
+        ret = acpi_gtdt_init(table, &platform_timer_count);
         if (ret) {
                 pr_err("Failed to init GTDT table.\n");
                 return ret;
@@ -1441,6 +1510,10 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
         if (ret)
                 return ret;
 
+        if (platform_timer_count &&
+            arch_timer_mem_acpi_init(platform_timer_count))
+                pr_err("Failed to initialize memory-mapped timer.\n");
+
         return arch_timer_common_init();
 }
 CLOCKSOURCE_ACPI_DECLARE(arch_timer, ACPI_SIG_GTDT, arch_timer_acpi_init);