Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932679AbaLBQz7 (ORCPT ); Tue, 2 Dec 2014 11:55:59 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:43313 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754102AbaLBQz5 (ORCPT ); Tue, 2 Dec 2014 11:55:57 -0500 Date: Tue, 2 Dec 2014 16:55:56 +0000 From: Will Deacon To: Mitchel Humpherys Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux-foundation.org" , Thierry Reding , Arnd Bergmann , Andrew Morton , Matt Wagantall Subject: Re: [PATCH RESEND v8] iopoll: Introduce memory-mapped IO polling macros Message-ID: <20141202165556.GH9917@arm.com> References: <1416860092-11620-1-git-send-email-mitchelh@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1416860092-11620-1-git-send-email-mitchelh@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 24, 2014 at 08:14:52PM +0000, Mitchel Humpherys wrote: > From: Matt Wagantall > > It is sometimes necessary to poll a memory-mapped register until its value > satisfies some condition. Introduce a family of convenience macros that do > this. Tight-looping, sleeping, and timing out can all be accomplished using > these macros. > > Cc: Thierry Reding > Cc: Will Deacon > Cc: Arnd Bergmann > Cc: Andrew Morton > Signed-off-by: Matt Wagantall > Signed-off-by: Mitchel Humpherys > --- > This patch was originally part of a series [1] for adding support for IOMMU > address translations through an ARM SMMU hardware register. The other > patch in the series (the one that actually uses these macros and implements > said hardware address translations) was Ack'd by the driver maintainer > there (Will Deacon) so I've pulled this patch out to avoid resending an > already Ack'd patch over and over again. > > In short, please see [1] for previous discussion and the first user of > these macros. > > This patch has been resent previously here [2], here [3], and here [4] on > 2014-10-30, 2014-11-06, and 2014-11-17, respectively. It has not changed > since [2] and has not received any comments since [1] on 2014-10-19. > Thanks to everyone who has taken a look at this. > > [1] http://thread.gmane.org/gmane.linux.kernel.iommu/7140 > [2] http://thread.gmane.org/gmane.linux.kernel/1818213 > [3] http://thread.gmane.org/gmane.linux.kernel/1823422 > [4] http://thread.gmane.org/gmane.linux.kernel.iommu/7394 Did this ever get queued? It would be pretty useful for a bunch of drivers that seem to copy-paste this sort of code. If it helps: Acked-by: Will Deacon Will > Changes since v7: > - sorted helper macros by size (b, w, l, q) > - removed some of the more esoteric (or flat-out bogus) helper macros > --- > include/linux/iopoll.h | 140 +++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 140 insertions(+) > create mode 100644 include/linux/iopoll.h > > diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h > new file mode 100644 > index 0000000000..bd161dae2d > --- /dev/null > +++ b/include/linux/iopoll.h > @@ -0,0 +1,140 @@ > +/* > + * Copyright (c) 2012-2014 The Linux Foundation. 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 and > + * only version 2 as published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + */ > + > +#ifndef _LINUX_IOPOLL_H > +#define _LINUX_IOPOLL_H > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +/** > + * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs > + * @op: accessor function (takes @addr as its only argument) > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops) > + * @timeout_us: Timeout in us, 0 means never timeout > + * > + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either > + * case, the last read value at @addr is stored in @val. Must not > + * be called from atomic context if sleep_us or timeout_us are used. > + * > + * When available, you'll probably want to use one of the specialized > + * macros defined below rather than this macro directly. > + */ > +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + might_sleep_if(sleep_us); \ > + for (;;) { \ > + (val) = op(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = op(addr); \ > + break; \ > + } \ > + if (sleep_us) \ > + usleep_range((sleep_us >> 2) + 1, sleep_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > +/** > + * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs > + * @op: accessor function (takes @addr as its only argument) > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @delay_us: Time to udelay between reads in us (0 tight-loops) > + * @timeout_us: Timeout in us, 0 means never timeout > + * > + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either > + * case, the last read value at @addr is stored in @val. > + * > + * When available, you'll probably want to use one of the specialized > + * macros defined below rather than this macro directly. > + */ > +#define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + for (;;) { \ > + (val) = op(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = op(addr); \ > + break; \ > + } \ > + if (delay_us) \ > + udelay(delay_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > + > +#define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us) > + > +#define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us) > + > +#define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us) > + > +#define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us) > + > +#define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us) > + > +#define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us) > + > +#define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us) > + > +#define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us) > + > +#define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#endif /* _LINUX_IOPOLL_H */ > -- > Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project > > -- 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/