From patchwork Mon Jan 27 15:27:01 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ezequiel Garcia X-Patchwork-Id: 3542661 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id DE2DC9F381 for ; Mon, 27 Jan 2014 15:27:59 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 434B820121 for ; Mon, 27 Jan 2014 15:27:55 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6E2CB200D4 for ; Mon, 27 Jan 2014 15:27:50 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W7o6E-0002nM-K2; Mon, 27 Jan 2014 15:27:46 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W7o6C-0000lY-77; Mon, 27 Jan 2014 15:27:44 +0000 Received: from top.free-electrons.com ([176.31.233.9] helo=mail.free-electrons.com) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W7o68-0000k7-Uk for linux-arm-kernel@lists.infradead.org; Mon, 27 Jan 2014 15:27:41 +0000 Received: by mail.free-electrons.com (Postfix, from userid 106) id 9C7BF812; Mon, 27 Jan 2014 16:27:20 +0100 (CET) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.7 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from localhost.localdomain (unknown [190.2.98.212]) by mail.free-electrons.com (Postfix) with ESMTPA id 29FDF7B2; Mon, 27 Jan 2014 16:27:15 +0100 (CET) From: Ezequiel Garcia To: , , Subject: [PATCH v5 01/20] ARM: Introduce atomic MMIO modify Date: Mon, 27 Jan 2014 12:27:01 -0300 Message-Id: <1390836440-12744-2-git-send-email-ezequiel.garcia@free-electrons.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1390836440-12744-1-git-send-email-ezequiel.garcia@free-electrons.com> References: <1390836440-12744-1-git-send-email-ezequiel.garcia@free-electrons.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140127_102741_221702_8624A345 X-CRM114-Status: GOOD ( 12.27 ) X-Spam-Score: -1.7 (-) Cc: Lior Amsalem , Andrew Lunn , Russell King - ARM Linux , Jason Cooper , Tawfik Bayouk , Daniel Lezcano , Wim Van Sebroeck , Arnd Bergmann , Ezequiel Garcia , Gregory Clement , Guenter Roeck , Sebastian Hesselbarth 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 X-Virus-Scanned: ClamAV using ClamSMTP Some SoC have MMIO regions that are shared across orthogonal subsystems. This commit implements a possible solution for the thread-safe access of such regions through a spinlock-protected API. Concurrent access is protected with a single spinlock for the entire MMIO address space. While this protects shared-registers, it also serializes access to unrelated/unshared registers. We add relaxed and non-relaxed variants, by using writel_relaxed and writel, respectively. The rationale for this is that some users may not require register write completion but only thread-safe access to a register. Cc: Russell King - ARM Linux Tested-by: Sebastian Hesselbarth Signed-off-by: Ezequiel Garcia --- Russell, Can you confirm this patch is on its way to v3.14? arch/arm/include/asm/io.h | 6 ++++++ arch/arm/kernel/io.c | 35 +++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index fbeb39c..8aa4cca 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -38,6 +38,12 @@ #define isa_bus_to_virt phys_to_virt /* + * Atomic MMIO-wide IO modify + */ +extern void atomic_io_modify(void __iomem *reg, u32 mask, u32 set); +extern void atomic_io_modify_relaxed(void __iomem *reg, u32 mask, u32 set); + +/* * Generic IO read/write. These perform native-endian accesses. Note * that some architectures will want to re-define __raw_{read,write}w. */ diff --git a/arch/arm/kernel/io.c b/arch/arm/kernel/io.c index dcd5b4d..9203cf8 100644 --- a/arch/arm/kernel/io.c +++ b/arch/arm/kernel/io.c @@ -1,6 +1,41 @@ #include #include #include +#include + +static DEFINE_RAW_SPINLOCK(__io_lock); + +/* + * Generic atomic MMIO modify. + * + * Allows thread-safe access to registers shared by unrelated subsystems. + * The access is protected by a single MMIO-wide lock. + */ +void atomic_io_modify_relaxed(void __iomem *reg, u32 mask, u32 set) +{ + unsigned long flags; + u32 value; + + raw_spin_lock_irqsave(&__io_lock, flags); + value = readl_relaxed(reg) & ~mask; + value |= (set & mask); + writel_relaxed(value, reg); + raw_spin_unlock_irqrestore(&__io_lock, flags); +} +EXPORT_SYMBOL(atomic_io_modify_relaxed); + +void atomic_io_modify(void __iomem *reg, u32 mask, u32 set) +{ + unsigned long flags; + u32 value; + + raw_spin_lock_irqsave(&__io_lock, flags); + value = readl_relaxed(reg) & ~mask; + value |= (set & mask); + writel(value, reg); + raw_spin_unlock_irqrestore(&__io_lock, flags); +} +EXPORT_SYMBOL(atomic_io_modify); /* * Copy data from IO memory space to "real" memory space.