From: Stephen Boyd <sboyd@codeaurora.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: [PATCHv7 02/11] clocksource: add generic dummy timer driver
Date: Mon, 3 Jun 2013 13:33:53 -0700 [thread overview]
Message-ID: <1370291642-13259-3-git-send-email-sboyd@codeaurora.org> (raw)
In-Reply-To: <1370291642-13259-1-git-send-email-sboyd@codeaurora.org>
From: Mark Rutland <mark.rutland@arm.com>
Several architectures have a dummy timer driver tightly coupled with
their broadcast code to support machines without cpu-local timers (or
where there is a lack of driver support).
Since 12ad100046: "clockevents: Add generic timer broadcast function"
it's been possible to write broadcast-capable timer drivers decoupled
from the broadcast mechanism. We can use this functionality to implement
a generic dummy timer driver that can be shared by all architectures
with generic tick broadcast (ARCH_HAS_TICK_BROADCAST).
This patch implements a generic dummy timer using this facility.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>,
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
[sboyd: Make percpu data static, use __this_cpu_ptr(), move to
early_initcall to properly register on each CPU, only
register if more than one CPU possible]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
drivers/clocksource/Makefile | 1 +
drivers/clocksource/dummy_timer.c | 69 +++++++++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+)
create mode 100644 drivers/clocksource/dummy_timer.c
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 8d979c7..1a17d76 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o
obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o
+obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o
diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/dummy_timer.c
new file mode 100644
index 0000000..1f55f96
--- /dev/null
+++ b/drivers/clocksource/dummy_timer.c
@@ -0,0 +1,69 @@
+/*
+ * linux/drivers/clocksource/dummy_timer.c
+ *
+ * Copyright (C) 2013 ARM Ltd.
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+
+static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt);
+
+static void dummy_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ /*
+ * Core clockevents code will call this when exchanging timer devices.
+ * We don't need to do anything here.
+ */
+}
+
+static void __cpuinit dummy_timer_setup(void)
+{
+ int cpu = smp_processor_id();
+ struct clock_event_device *evt = __this_cpu_ptr(&dummy_timer_evt);
+
+ evt->name = "dummy_timer";
+ evt->features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT |
+ CLOCK_EVT_FEAT_DUMMY;
+ evt->rating = 100;
+ evt->set_mode = dummy_timer_set_mode;
+ evt->cpumask = cpumask_of(cpu);
+
+ clockevents_register_device(evt);
+}
+
+static int __cpuinit dummy_timer_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
+ dummy_timer_setup();
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block dummy_timer_cpu_nb __cpuinitdata = {
+ .notifier_call = dummy_timer_cpu_notify,
+};
+
+static int __init dummy_timer_register(void)
+{
+ int err = register_cpu_notifier(&dummy_timer_cpu_nb);
+ if (err)
+ return err;
+
+ /* We won't get a call on the boot CPU, so register immediately */
+ if (num_possible_cpus() > 1)
+ dummy_timer_setup();
+
+ return 0;
+}
+early_initcall(dummy_timer_register);
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation
next prev parent reply other threads:[~2013-06-03 20:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-03 20:33 [PATCHv7 00/11] Remove ARM local timer API Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 01/11] clockevents: Prefer CPU local devices over global devices Stephen Boyd
2013-06-06 15:12 ` Daniel Lezcano
2013-06-06 18:04 ` Stephen Boyd
2013-06-06 22:30 ` Daniel Lezcano
2013-06-06 22:38 ` Stephen Boyd
2013-06-12 21:44 ` Stephen Boyd
2013-06-13 9:33 ` Daniel Lezcano
2013-06-13 13:15 ` Thomas Gleixner
2013-06-13 18:39 ` Stephen Boyd
2013-06-13 20:16 ` Sören Brinkmann
2013-06-18 10:22 ` Mark Rutland
2013-06-19 16:30 ` Stephen Boyd
2013-06-21 17:07 ` Stephen Boyd
2013-06-24 20:07 ` Stephen Boyd
2013-06-24 20:30 ` [tip:timers/core] " tip-bot for Stephen Boyd
2013-06-03 20:33 ` Stephen Boyd [this message]
2013-06-06 16:23 ` [PATCHv7 02/11] clocksource: add generic dummy timer driver Daniel Lezcano
2013-06-24 20:30 ` [tip:timers/core] clocksource: Add " tip-bot for Mark Rutland
2013-06-03 20:33 ` [PATCHv7 03/11] ARM: smp: Remove duplicate dummy timer implementation Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 04/11] ARM: smp_twd: Divorce smp_twd from local timer API Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 05/11] ARM: OMAP2+: Divorce " Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 06/11] ARM: EXYNOS4: Divorce mct " Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 07/11] ARM: PRIMA2: Divorce timer-marco " Stephen Boyd
2013-06-03 20:33 ` [PATCHv7 08/11] ARM: msm: Divorce msm_timer " Stephen Boyd
2013-06-03 20:34 ` [PATCHv7 09/11] clocksource: time-armada-370-xp: Fix sparse warning Stephen Boyd
2013-06-03 20:34 ` [PATCHv7 10/11] clocksource: time-armada-370-xp: Divorce from local timer API Stephen Boyd
2013-06-03 20:34 ` [PATCHv7 11/11] ARM: smp: Remove " Stephen Boyd
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