From patchwork Wed Aug 29 21:25:24 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 1385921 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 E8BE1DF2AB for ; Wed, 29 Aug 2012 21:28:59 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1T6plv-0006o5-W0; Wed, 29 Aug 2012 21:26:00 +0000 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1T6plt-0006nU-4J for linux-arm-kernel@lists.infradead.org; Wed, 29 Aug 2012 21:25:57 +0000 Received: from mudshark.cambridge.arm.com (mudshark.cambridge.arm.com [10.1.79.58]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id q7TLPVE7022419; Wed, 29 Aug 2012 22:25:31 +0100 (BST) Received: by mudshark.cambridge.arm.com (Postfix, from userid 1000) id D9A74C02E8; Wed, 29 Aug 2012 22:25:30 +0100 (BST) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 2/2] ARM: delay: add registration mechanism for delay timer sources Date: Wed, 29 Aug 2012 22:25:24 +0100 Message-Id: <1346275524-13817-2-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1346275524-13817-1-git-send-email-will.deacon@arm.com> References: <1346275524-13817-1-git-send-email-will.deacon@arm.com> X-Spam-Note: CRM114 invocation failed X-Spam-Score: -7.1 (-------) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-7.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [217.140.96.50 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.2 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Will Deacon , sboyd@codeaurora.org, Jonathan Austin X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Jonathan Austin The current timer-based delay loop relies on the architected timer to initiate the switch away from the polling-based implementation. This is unfortunate for platforms without the architected timers but with a suitable delay source (that is, constant frequency, always powered-up and ticking as long as the CPUs are online). This patch introduces a registration mechanism for the delay timer (which provides an unconditional read_current_timer implementation) and updates the architected timer code to use the new interface. Signed-off-by: Jonathan Austin Signed-off-by: Will Deacon Reviewed-by: Stephen Boyd --- v2: Changed prototype for low-level read_current_timer to return the timer value directly. arch/arm/include/asm/arch_timer.h | 1 - arch/arm/include/asm/delay.h | 9 +++++++++ arch/arm/include/asm/timex.h | 6 ------ arch/arm/kernel/arch_timer.c | 17 ++++++++--------- arch/arm/lib/delay.c | 31 ++++++++++++++++++++++--------- 5 files changed, 39 insertions(+), 25 deletions(-) diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 62e7547..88401c2 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -4,7 +4,6 @@ #include #ifdef CONFIG_ARM_ARCH_TIMER -#define ARCH_HAS_READ_CURRENT_TIMER int arch_timer_of_register(void); int arch_timer_sched_clock_init(void); #else diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h index dc61451..50928e8 100644 --- a/arch/arm/include/asm/delay.h +++ b/arch/arm/include/asm/delay.h @@ -15,6 +15,11 @@ #ifndef __ASSEMBLY__ +struct delay_timer { + unsigned long (*read_current_timer)(void); + unsigned long freq; +}; + extern struct arm_delay_ops { void (*delay)(unsigned long); void (*const_udelay)(unsigned long); @@ -56,6 +61,10 @@ extern void __loop_delay(unsigned long loops); extern void __loop_udelay(unsigned long usecs); extern void __loop_const_udelay(unsigned long); +/* Delay-loop timer registration. */ +#define ARCH_HAS_READ_CURRENT_TIMER +extern void register_current_timer_delay(struct delay_timer *timer); + #endif /* __ASSEMBLY__ */ #endif /* defined(_ARM_DELAY_H) */ diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h index ce11944..9acc135 100644 --- a/arch/arm/include/asm/timex.h +++ b/arch/arm/include/asm/timex.h @@ -12,15 +12,9 @@ #ifndef _ASMARM_TIMEX_H #define _ASMARM_TIMEX_H -#include #include typedef unsigned long cycles_t; - -#ifdef ARCH_HAS_READ_CURRENT_TIMER #define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; }) -#else -#define get_cycles() (0) -#endif #endif diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c index cf25880..700917a 100644 --- a/arch/arm/kernel/arch_timer.c +++ b/arch/arm/kernel/arch_timer.c @@ -21,6 +21,7 @@ #include #include +#include #include #include #include @@ -31,8 +32,7 @@ static int arch_timer_ppi; static int arch_timer_ppi2; static struct clock_event_device __percpu **arch_timer_evt; - -extern void init_current_timer_delay(unsigned long freq); +static struct delay_timer arch_delay_timer; /* * Architected system timer support. @@ -225,12 +225,9 @@ static cycle_t arch_counter_read(struct clocksource *cs) return arch_counter_get_cntpct(); } -int read_current_timer(unsigned long *timer_val) +static unsigned long arch_timer_read_current_timer(void) { - if (!arch_timer_rate) - return -ENXIO; - *timer_val = arch_counter_get_cntpct(); - return 0; + return arch_counter_get_cntpct(); } static struct clocksource clocksource_counter = { @@ -302,11 +299,13 @@ static int __init arch_timer_register(void) arch_timer_global_evt.cpumask = cpumask_of(0); err = arch_timer_setup(&arch_timer_global_evt); } - if (err) goto out_free_irq; - init_current_timer_delay(arch_timer_rate); + /* Use the architected timer for the delay loop. */ + arch_delay_timer.read_current_timer = &arch_timer_read_current_timer; + arch_delay_timer.freq = arch_timer_rate; + register_current_timer_delay(&arch_delay_timer); return 0; out_free_irq: diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c index 395d5fb..fe6f4fb 100644 --- a/arch/arm/lib/delay.c +++ b/arch/arm/lib/delay.c @@ -34,7 +34,14 @@ struct arm_delay_ops arm_delay_ops = { .udelay = __loop_udelay, }; -#ifdef ARCH_HAS_READ_CURRENT_TIMER +static struct delay_timer *delay_timer; +static bool delay_calibrated; + +int read_current_timer(unsigned long *timer_val) +{ + return delay_timer ? delay_timer->read_current_timer() : -ENXIO; +} + static void __timer_delay(unsigned long cycles) { cycles_t start = get_cycles(); @@ -55,18 +62,24 @@ static void __timer_udelay(unsigned long usecs) __timer_const_udelay(usecs * UDELAY_MULT); } -void __init init_current_timer_delay(unsigned long freq) +void __init register_current_timer_delay(struct delay_timer *timer) { - pr_info("Switching to timer-based delay loop\n"); - lpj_fine = freq / HZ; - loops_per_jiffy = lpj_fine; - arm_delay_ops.delay = __timer_delay; - arm_delay_ops.const_udelay = __timer_const_udelay; - arm_delay_ops.udelay = __timer_udelay; + if (!delay_calibrated) { + pr_info("Switching to timer-based delay loop\n"); + delay_timer = timer; + lpj_fine = timer->freq / HZ; + loops_per_jiffy = lpj_fine; + arm_delay_ops.delay = __timer_delay; + arm_delay_ops.const_udelay = __timer_const_udelay; + arm_delay_ops.udelay = __timer_udelay; + delay_calibrated = true; + } else { + pr_info("Ignoring duplicate/late registration of read_current_timer delay\n"); + } } unsigned long __cpuinit calibrate_delay_is_known(void) { + delay_calibrated = true; return lpj_fine; } -#endif