[v16,14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

Message ID 1479304148-2965-15-git-send-email-fu.wei@linaro.org
State New
Headers show

Commit Message

Fu Wei Nov. 16, 2016, 1:49 p.m.
From: Fu Wei <fu.wei@linaro.org>


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>

---
 drivers/clocksource/arm_arch_timer.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

-- 
2.7.4

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Comments

Mark Rutland Nov. 18, 2016, 8:20 p.m. | #1
On Wed, Nov 16, 2016 at 09:49:07PM +0800, fu.wei@linaro.org wrote:
> From: Fu Wei <fu.wei@linaro.org>

> 

> 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>

> ---

>  drivers/clocksource/arm_arch_timer.c | 26 +++++++++++++++++++++++++-

>  1 file changed, 25 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c

> index c494ca8..0aad60a 100644

> --- a/drivers/clocksource/arm_arch_timer.c

> +++ b/drivers/clocksource/arm_arch_timer.c

> @@ -1067,7 +1067,28 @@ 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_acpi_init(void)

> +{

> +	struct arch_timer_mem *timer_mem;

> +	int ret = 0;

> +	int i = 0;

> +

> +	timer_mem = kzalloc(sizeof(*timer_mem), GFP_KERNEL);


Why do you need it zeroed? You don't clear it between iterations, so
either you don't need this, or you have a bug in the loop.

> +	if (!timer_mem)

> +		return -ENOMEM;

> +

> +	while (!gtdt_arch_timer_mem_init(timer_mem, i)) {


Huh?

Why doesn't GTDT expose a function to fill in the entire arch_timer_mem
in one go?

There shouldn't be multiple instances, as far as I am aware. Am I
mistaken?

> +		ret = arch_timer_mem_init(timer_mem);

> +		if (ret)

> +			break;

> +		i++;

> +	}

> +

> +	kfree(timer_mem);

> +	return ret;

> +}



Regardless, arch_timer_mem is small enough that you don't need dynamic
allocaiton. Just put it on the stack, e.g.

static int __init arch_timer_mem_acpi_init(void)
{
	int i = 0;
	struct arch_timer_mem timer_mem;

	while (!gtdt_arch_timer_mem_init(timer_mem, i)) {
		int ret = arch_timer_mem_init();
		if (ret)
			return ret;
		i++
	}

	return 0;
}

Thanks,
Mark.
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Patch hide | download patch | download mbox

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index c494ca8..0aad60a 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1067,7 +1067,28 @@  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_acpi_init(void)
+{
+	struct arch_timer_mem *timer_mem;
+	int ret = 0;
+	int i = 0;
+
+	timer_mem = kzalloc(sizeof(*timer_mem), GFP_KERNEL);
+	if (!timer_mem)
+		return -ENOMEM;
+
+	while (!gtdt_arch_timer_mem_init(timer_mem, i)) {
+		ret = arch_timer_mem_init(timer_mem);
+		if (ret)
+			break;
+		i++;
+	}
+
+	kfree(timer_mem);
+	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;
@@ -1104,6 +1125,9 @@  static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 	/* Get the frequency from CNTFRQ */
 	arch_timer_detect_rate(NULL);
 
+	if (arch_timer_mem_acpi_init())
+		pr_err("Failed to initialize memory-mapped timer.\n");
+
 	ret = arch_timer_init();
 
 error: