[PATCH v24 10/11] clocksource: arm_arch_timer: add GTDT support for memory-mapped timer

fu.wei at linaro.org
2017-04-14T18:40:13Z

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>
---
drivers/clocksource/arm_arch_timer.c | 78 ++++++++++++++++++++++++++++++++++--
1 file changed, 75 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 05f2f7a..8981173 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1385,10 +1385,78 @@ 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");
@@ -1397,7 +1465,7 @@ 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;
@@ -1440,6 +1508,10 @@ 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);
--
2.9.3