[PATCH v8 17/21] clocksource / arch_timer: Parse GTDT to initialize arch timer

Rafael J. Wysocki
2015-02-02T22:23:58Z

On Monday, February 02, 2015 08:45:45 PM Hanjun Guo wrote:
> 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>
> 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>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
> arch/arm64/kernel/time.c | 7 ++
> drivers/clocksource/arm_arch_timer.c | 132 ++++++++++++++++++++++++++++-------

An ACK from Thomas Gleixner is necessary for that.

> include/linux/clocksource.h | 6 ++
> 3 files changed, 118 insertions(+), 27 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 095c177..407aa63 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>
> @@ -370,8 +371,12 @@ 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
> @@ -690,28 +695,8 @@ 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
> @@ -730,13 +715,39 @@ 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)
> {
> @@ -803,3 +814,70 @@ 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 abcafaa..af6155a 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 */
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.