Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755222Ab3EMT0X (ORCPT ); Mon, 13 May 2013 15:26:23 -0400 Received: from wolverine01.qualcomm.com ([199.106.114.254]:47450 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754194Ab3EMT0R (ORCPT ); Mon, 13 May 2013 15:26:17 -0400 X-IronPort-AV: E=Sophos;i="4.87,663,1363158000"; d="scan'208";a="46754205" From: Stephen Boyd To: John Stultz , Thomas Gleixner Cc: Mark Rutland , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCHv6 02/11] clocksource: add generic dummy timer driver Date: Mon, 13 May 2013 12:26:06 -0700 Message-Id: <1368473175-4841-3-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 1.8.3.rc1.25.g423ecb0.dirty In-Reply-To: <1368473175-4841-1-git-send-email-sboyd@codeaurora.org> References: <1368473175-4841-1-git-send-email-sboyd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3987 Lines: 120 From: Mark Rutland 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 Cc: John Stultz Cc: Thomas Gleixner [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 --- 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 +#include +#include +#include +#include + +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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/