On Fri, Jan 17, 2014 at 12:25:11PM +0000, Hanjun Guo wrote:

ACPI GTDT (Generic Timer Description Table) contains information for
arch timer initialization, this patch use this table to probe arm timer.

GTDT table is used for ARM/ARM64 only, please refer to chapter 5.2.24
of ACPI 5.0 spec for detailed inforamtion

Signed-off-by: Amit Daniel Kachhap <redacted>
Signed-off-by: Hanjun Guo <redacted>
---
 drivers/clocksource/arm_arch_timer.c |  100 +++++++++++++++++++++++++++++-----
 1 file changed, 85 insertions(+), 15 deletions(-)

[...]

+static void __init register_arch_interrupt(u32 interrupt, u32 flags,
+					int *arch_timer_ppi)
+{
+	int trigger, polarity;
+
+	if (!interrupt || !arch_timer_ppi)
+		return;
+
+	trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
+			: ACPI_LEVEL_SENSITIVE;
+
+	polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
+			: ACPI_ACTIVE_HIGH;
+
+	*arch_timer_ppi = acpi_register_gsi(NULL, interrupt, trigger,
+						polarity);
+}

Why does this take a pointer to the irq rather than returning the irq
(as with irq_of_parse_and_map)?

This looks awfully generic. Are the timer interrupts encoded specially
or is this useful for parsing other interrupts?

+
+static int __init acpi_parse_gtdt(struct acpi_table_header *table)
+{
+	struct acpi_table_gtdt *gtdt;
+
+	gtdt = (struct acpi_table_gtdt *)table;
+	if (!gtdt)
+		return -EINVAL;
+
+	arch_timer_rate = arch_timer_get_cntfrq();
+
+	if (!arch_timer_rate) {
+		pr_warn("arch_timer: Could not get frequency from CNTFREG\n");

s/CNTFREG/CNTFREQ/

This is probably worth a pr_err at least, the system is unlikely to get
very far if the timers don't work.

Thanks,
Mark.