[PATCH v4 15/18] ARM64 / ACPI: Parse GTDT to initialize arch timer

Hanjun Guo
2014-09-12T14:00:13Z

Using the information presented by GTDT to initialize the arch
timer (not memory-mapped).

Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
arch/arm64/kernel/time.c | 7 ++
drivers/clocksource/arm_arch_timer.c | 117 ++++++++++++++++++++++++++++------
include/linux/clocksource.h | 6 ++
3 files changed, 111 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index 1a7125c..42f9195 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -35,6 +35,7 @@
#include <linux/delay.h>
#include <linux/clocksource.h>
#include <linux/clk-provider.h>
+#include <linux/acpi.h>

#include <clocksource/arm_arch_timer.h>

@@ -72,6 +73,12 @@ void __init time_init(void)

tick_setup_hrtimer_broadcast();

+ /*
+ * Since ACPI or FDT will only one be available in the system,
+ * we can use acpi_generic_timer_init() here safely
+ */
+ acpi_generic_timer_init();
+
arch_timer_rate = arch_timer_get_rate();
if (!arch_timer_rate)
panic("Unable to initialise architected timer.\n");
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5163ec1..397783f 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -21,6 +21,7 @@
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/sched_clock.h>
+#include <linux/acpi.h>

#include <asm/arch_timer.h>
#include <asm/virt.h>
@@ -338,8 +339,12 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
if (arch_timer_rate)
return;

- /* Try to determine the frequency from the device tree or CNTFRQ */
- if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
+ /*
+ * Try to determine the frequency from the device tree or CNTFRQ,
+ * if ACPI is enabled, get the frequency from CNTFRQ ONLY.
+ */
+ if (!acpi_disabled ||
+ of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
if (cntbase)
arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
else
@@ -635,20 +640,8 @@ static void __init arch_timer_common_init(void)
arch_timer_arch_init();
}

-static void __init arch_timer_init(struct device_node *np)
+static void __init arch_timer_init(void)
{
- int i;
-
- if (arch_timers_present & ARCH_CP15_TIMER) {
- pr_warn("arch_timer: multiple nodes in dt, skipping\n");
- return;
- }
-
- arch_timers_present |= ARCH_CP15_TIMER;
- for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
- arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
- arch_timer_detect_rate(NULL, np);
-
/*
* If HYP mode is available, we know that the physical timer
* has been configured to be accessible from PL1. Use it, so
@@ -667,13 +660,31 @@ static void __init arch_timer_init(struct device_node *np)
}
}

- arch_timer_c3stop = !of_property_read_bool(np, "always-on");
-
arch_timer_register();
arch_timer_common_init();
}
-CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_init);
-CLOCKSOURCE_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_init);
+
+static void __init arch_timer_of_init(struct device_node *np)
+{
+ int i;
+
+ if (arch_timers_present & ARCH_CP15_TIMER) {
+ pr_warn("arch_timer: multiple nodes in dt, skipping\n");
+ return;
+ }
+
+ arch_timers_present |= ARCH_CP15_TIMER;
+ for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
+ arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
+
+ arch_timer_detect_rate(NULL, np);
+
+ arch_timer_c3stop = !of_property_read_bool(np, "always-on");
+
+ arch_timer_init();
+}
+CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_of_init);
+CLOCKSOURCE_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_of_init);

static void __init arch_timer_mem_init(struct device_node *np)
{
@@ -740,3 +751,71 @@ static void __init arch_timer_mem_init(struct device_node *np)
}
CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
arch_timer_mem_init);
+
+#ifdef CONFIG_ACPI
+static int __init
+map_generic_timer_interrupt(u32 interrupt, u32 flags)
+{
+ int trigger, polarity;
+
+ if (!interrupt)
+ return 0;
+
+ trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
+ : ACPI_LEVEL_SENSITIVE;
+
+ polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
+ : ACPI_ACTIVE_HIGH;
+
+ return acpi_register_gsi(NULL, interrupt, trigger, polarity);
+}
+
+/* Initialize per-processor generic timer */
+static int __init arch_timer_acpi_init(struct acpi_table_header *table)
+{
+ struct acpi_table_gtdt *gtdt;
+
+ if (arch_timers_present & ARCH_CP15_TIMER) {
+ pr_warn("arch_timer: already initialized, skipping\n");
+ return -EINVAL;
+ }
+
+ gtdt = container_of(table, struct acpi_table_gtdt, header);
+
+ arch_timers_present |= ARCH_CP15_TIMER;
+
+ arch_timer_ppi[PHYS_SECURE_PPI] =
+ map_generic_timer_interrupt(gtdt->secure_el1_interrupt,
+ gtdt->secure_el1_flags);
+
+ arch_timer_ppi[PHYS_NONSECURE_PPI] =
+ map_generic_timer_interrupt(gtdt->non_secure_el1_interrupt,
+ gtdt->non_secure_el1_flags);
+
+ arch_timer_ppi[VIRT_PPI] =
+ map_generic_timer_interrupt(gtdt->virtual_timer_interrupt,
+ gtdt->virtual_timer_flags);
+
+ arch_timer_ppi[HYP_PPI] =
+ map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt,
+ gtdt->non_secure_el2_flags);
+
+ /* Get the frequency from CNTFRQ */
+ arch_timer_detect_rate(NULL, NULL);
+
+ /* Always-on capability */
+ arch_timer_c3stop = !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);
+
+ arch_timer_init();
+ return 0;
+}
+
+/* Initialize all the generic timers presented in GTDT */
+void __init acpi_generic_timer_init(void)
+{
+ if (acpi_disabled)
+ return;
+
+ acpi_table_parse(ACPI_SIG_GTDT, arch_timer_acpi_init);
+}
+#endif
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 653f0e2..5839f98 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -346,4 +346,10 @@ extern void clocksource_of_init(void);
static inline void clocksource_of_init(void) {}
#endif

+#ifdef CONFIG_ACPI
+void acpi_generic_timer_init(void);
+#else
+static inline void acpi_generic_timer_init(void) {}
+#endif
+
#endif /* _LINUX_CLOCKSOURCE_H */
--
1.7.9.5