From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: [PATCH V4 1/5] The macro spin_event_timeout() takes a condition and timeout value Date: Mon, 25 May 2009 18:15:07 -0400 Message-ID: <20090525221507.21370.68301.stgit@terra> References: <20090525221406.21370.30326.stgit@terra> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-gx0-f158.google.com (mail-gx0-f158.google.com [209.85.217.158]) by alsa0.perex.cz (Postfix) with ESMTP id A2BB12434C for ; Tue, 26 May 2009 00:15:07 +0200 (CEST) Received: by mail-gx0-f158.google.com with SMTP id 2so6650923gxk.8 for ; Mon, 25 May 2009 15:15:07 -0700 (PDT) In-Reply-To: <20090525221406.21370.30326.stgit@terra> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: grant.likely@secretlab.ca, linuxppc-dev@ozlabs.org, alsa-devel@alsa-project.org, broonie@sirena.org.uk, timur@freescale.com List-Id: alsa-devel@alsa-project.org (in microseconds) as parameters. It spins until either the condition is true or the timeout expires. It returns the result of the condition when the loop was terminated. This primary purpose of this macro is to poll on a hardware register until a status bit changes. The timeout ensures that the loop still terminates if the bit doesn't change as expected. This macro makes it easier for driver developers to perform this kind of operation properly. Signed-off-by: Timur Tabi --- arch/powerpc/include/asm/delay.h | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/include/asm/delay.h b/arch/powerpc/include/asm/delay.h index f9200a6..fedf037 100644 --- a/arch/powerpc/include/asm/delay.h +++ b/arch/powerpc/include/asm/delay.h @@ -2,8 +2,11 @@ #define _ASM_POWERPC_DELAY_H #ifdef __KERNEL__ +#include + /* * Copyright 1996, Paul Mackerras. + * Copyright (C) 2009 Freescale Semiconductor, Inc. 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 @@ -30,5 +33,35 @@ extern void udelay(unsigned long usecs); #define mdelay(n) udelay((n) * 1000) #endif +/** + * spin_event_timeout - spin until a condition gets true or a timeout elapses + * @condition: a C expression to evalate + * @timeout: timeout, in microseconds + * @delay: the number of microseconds to delay between eache evaluation of + * @condition + * @rc: the last value of the condition + * + * The process spins until the condition evaluates to true (non-zero) or the + * timeout elapses. Upon exit, @rc contains the value of the condition. This + * allows you to test the condition without incurring any side effects. + * + * This primary purpose of this macro is to poll on a hardware register + * until a status bit changes. The timeout ensures that the loop still + * terminates even if the bit never changes. The delay is for devices that + * need a delay in between successive reads. + * + * gcc will optimize out the if-statement if @delay is a constant. + */ +#define spin_event_timeout(condition, timeout, delay, rc) \ +{ \ + unsigned long __loops = tb_ticks_per_usec * timeout; \ + unsigned long __start = get_tbl(); \ + while ((rc = (condition)) && (tb_ticks_since(__start) <= __loops)) \ + if (delay) \ + udelay(delay); \ + else \ + cpu_relax(); \ +} + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_DELAY_H */ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-gx0-f220.google.com (mail-gx0-f220.google.com [209.85.217.220]) by ozlabs.org (Postfix) with ESMTP id 76226DE0B2 for ; Tue, 26 May 2009 08:15:09 +1000 (EST) Received: by gxk20 with SMTP id 20so2168464gxk.9 for ; Mon, 25 May 2009 15:15:07 -0700 (PDT) Subject: [PATCH V4 1/5] The macro spin_event_timeout() takes a condition and timeout value To: grant.likely@secretlab.ca, linuxppc-dev@ozlabs.org, alsa-devel@alsa-project.org, broonie@sirena.org.uk, timur@freescale.com From: Jon Smirl Date: Mon, 25 May 2009 18:15:07 -0400 Message-ID: <20090525221507.21370.68301.stgit@terra> In-Reply-To: <20090525221406.21370.30326.stgit@terra> References: <20090525221406.21370.30326.stgit@terra> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , (in microseconds) as parameters. It spins until either the condition is true or the timeout expires. It returns the result of the condition when the loop was terminated. This primary purpose of this macro is to poll on a hardware register until a status bit changes. The timeout ensures that the loop still terminates if the bit doesn't change as expected. This macro makes it easier for driver developers to perform this kind of operation properly. Signed-off-by: Timur Tabi --- arch/powerpc/include/asm/delay.h | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/include/asm/delay.h b/arch/powerpc/include/asm/delay.h index f9200a6..fedf037 100644 --- a/arch/powerpc/include/asm/delay.h +++ b/arch/powerpc/include/asm/delay.h @@ -2,8 +2,11 @@ #define _ASM_POWERPC_DELAY_H #ifdef __KERNEL__ +#include + /* * Copyright 1996, Paul Mackerras. + * Copyright (C) 2009 Freescale Semiconductor, Inc. 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 @@ -30,5 +33,35 @@ extern void udelay(unsigned long usecs); #define mdelay(n) udelay((n) * 1000) #endif +/** + * spin_event_timeout - spin until a condition gets true or a timeout elapses + * @condition: a C expression to evalate + * @timeout: timeout, in microseconds + * @delay: the number of microseconds to delay between eache evaluation of + * @condition + * @rc: the last value of the condition + * + * The process spins until the condition evaluates to true (non-zero) or the + * timeout elapses. Upon exit, @rc contains the value of the condition. This + * allows you to test the condition without incurring any side effects. + * + * This primary purpose of this macro is to poll on a hardware register + * until a status bit changes. The timeout ensures that the loop still + * terminates even if the bit never changes. The delay is for devices that + * need a delay in between successive reads. + * + * gcc will optimize out the if-statement if @delay is a constant. + */ +#define spin_event_timeout(condition, timeout, delay, rc) \ +{ \ + unsigned long __loops = tb_ticks_per_usec * timeout; \ + unsigned long __start = get_tbl(); \ + while ((rc = (condition)) && (tb_ticks_since(__start) <= __loops)) \ + if (delay) \ + udelay(delay); \ + else \ + cpu_relax(); \ +} + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_DELAY_H */