clocksource / arch_timer: Parse GTDT to initialize arch timer

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

CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: Thomas Gleixner <tglx@linutronix.de>
Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Yijing Wang <wangyijing@huawei.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
Tested-by: Timur Tabi <timur@codeaurora.org>
Tested-by: Robert Richter <rrichter@cavium.com>
Acked-by: Robert Richter <rrichter@cavium.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

3 files changed, 118 insertions, 27 deletions

diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index 1a7125c3099b..42f9195cf2f8 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 a3025e7ae35f..ea62fc79e1e8 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -22,6 +22,7 @@
 #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>
@@ -371,8 +372,12 @@ 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
@@ -691,28 +696,8 @@ 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 we cannot rely on firmware initializing the timer registers then
-         * we should use the physical timers instead.
-         */
-        if (IS_ENABLED(CONFIG_ARM) &&
-            of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
-                        arch_timer_use_virtual = false;
-
         /*
          * If HYP mode is available, we know that the physical timer
          * has been configured to be accessible from PL1. Use it, so
@@ -731,13 +716,39 @@ 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");
+
+        /*
+         * If we cannot rely on firmware initializing the timer registers then
+         * we should use the physical timers instead.
+         */
+        if (IS_ENABLED(CONFIG_ARM) &&
+            of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
+                        arch_timer_use_virtual = false;
+
+        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)
 {
@@ -804,3 +815,70 @@ 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 9c78d15d33e4..2b2e1f80c519 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -244,4 +244,10 @@ 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 */