From patchwork Thu Mar 7 00:03:57 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 2229041 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id C1A3BDF23A for ; Thu, 7 Mar 2013 00:08:59 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UDOKE-0007Tt-31; Thu, 07 Mar 2013 00:04:47 +0000 Received: from wolverine01.qualcomm.com ([199.106.114.254]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UDOJf-0007L1-Rb for linux-arm-kernel@lists.infradead.org; Thu, 07 Mar 2013 00:04:13 +0000 X-IronPort-AV: E=Sophos;i="4.84,798,1355126400"; d="scan'208";a="27738007" Received: from pdmz-ns-mip.qualcomm.com (HELO mostmsg01.qualcomm.com) ([199.106.114.10]) by wolverine01.qualcomm.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 06 Mar 2013 16:04:08 -0800 Received: from sboyd-linux.qualcomm.com (pdmz-ns-snip_218_1.qualcomm.com [192.168.218.1]) by mostmsg01.qualcomm.com (Postfix) with ESMTPA id 4C21D10004DF; Wed, 6 Mar 2013 16:04:08 -0800 (PST) From: Stephen Boyd To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 01/10] clocksource: add generic dummy timer driver Date: Wed, 6 Mar 2013 16:03:57 -0800 Message-Id: <1362614646-24113-2-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 1.8.2.rc2.4.g7799588 In-Reply-To: <1362614646-24113-1-git-send-email-sboyd@codeaurora.org> References: <1362614646-24113-1-git-send-email-sboyd@codeaurora.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130306_190412_202828_DFF37632 X-CRM114-Status: GOOD ( 17.07 ) X-Spam-Score: -4.2 (----) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-4.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [199.106.114.254 listed in list.dnswl.org] -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Mark Rutland , linux-arm-msm@vger.kernel.org, Thomas Gleixner , John Stultz , linux-kernel@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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(), s/dummy/dummy_timer/] Signed-off-by: Stephen Boyd --- drivers/clocksource/Makefile | 1 + drivers/clocksource/dummy_timer.c | 67 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) create mode 100644 drivers/clocksource/dummy_timer.c diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index 4d8283a..655d718 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -22,3 +22,4 @@ obj-$(CONFIG_VT8500_TIMER) += vt8500_timer.o obj-$(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..7e1ce45 --- /dev/null +++ b/drivers/clocksource/dummy_timer.c @@ -0,0 +1,67 @@ +/* + * 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 + +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 */ + dummy_timer_setup(); + + return 0; +} +device_initcall(dummy_timer_register);