From patchwork Tue Jan 29 07:51:05 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 2060261 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork1.kernel.org (Postfix) with ESMTP id 7D7E23FDD1 for ; Tue, 29 Jan 2013 07:59:04 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1U063s-00012Z-Gz; Tue, 29 Jan 2013 07:56:56 +0000 Received: from relais.videotron.ca ([24.201.245.36]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1U05yp-0005i3-25 for linux-arm-kernel@lists.infradead.org; Tue, 29 Jan 2013 07:51:45 +0000 Received: from yoda.home ([24.202.213.203]) by VL-VM-MR003.ip.videotron.ca (Oracle Communications Messaging Exchange Server 7u4-22.01 64bit (built Apr 21 2011)) with ESMTP id <0MHD000PGN5M8M90@VL-VM-MR003.ip.videotron.ca> for linux-arm-kernel@lists.infradead.org; Tue, 29 Jan 2013 02:51:22 -0500 (EST) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTP id 6C6752DA0142; Tue, 29 Jan 2013 02:51:22 -0500 (EST) From: Nicolas Pitre To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 10/15] ARM: vexpress/dcscb: add CPU use counts to the power up/down API implementation Date: Tue, 29 Jan 2013 02:51:05 -0500 Message-id: <1359445870-18925-11-git-send-email-nicolas.pitre@linaro.org> X-Mailer: git-send-email 1.8.1.2 In-reply-to: <1359445870-18925-1-git-send-email-nicolas.pitre@linaro.org> References: <1359445870-18925-1-git-send-email-nicolas.pitre@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130129_025143_279785_491A7FD1 X-CRM114-Status: GOOD ( 16.17 ) X-Spam-Score: -1.9 (-) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-1.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [24.201.245.36 listed in list.dnswl.org] -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Dave Martin , Lorenzo Pieralisi , Pawel Moll , Catalin Marinas , Will Deacon , Santosh Shilimkar 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 It is possible for a CPU to be told to power up before it managed to power itself down. Solve this race with a usage count as mandated by the API definition. Signed-off-by: nicolas Pitre Reviewed-by: Santosh Shilimkar --- arch/arm/mach-vexpress/dcscb.c | 77 +++++++++++++++++++++++++++++++++--------- 1 file changed, 61 insertions(+), 16 deletions(-) diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c index 677ced9efc..f993608944 100644 --- a/arch/arm/mach-vexpress/dcscb.c +++ b/arch/arm/mach-vexpress/dcscb.c @@ -45,6 +45,7 @@ static arch_spinlock_t dcscb_lock = __ARCH_SPIN_LOCK_UNLOCKED; static void __iomem *dcscb_base; +static int dcscb_use_count[4][2]; static int dcscb_power_up(unsigned int cpu, unsigned int cluster) { @@ -61,14 +62,27 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster) local_irq_disable(); arch_spin_lock(&dcscb_lock); - rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); - if (rst_hold & (1 << 8)) { - /* remove cluster reset and add individual CPU's reset */ - rst_hold &= ~(1 << 8); - rst_hold |= 0xf; + dcscb_use_count[cpu][cluster]++; + if (dcscb_use_count[cpu][cluster] == 1) { + rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); + if (rst_hold & (1 << 8)) { + /* remove cluster reset and add individual CPU's reset */ + rst_hold &= ~(1 << 8); + rst_hold |= 0xf; + } + rst_hold &= ~(cpumask | (cpumask << 4)); + writel(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + } else if (dcscb_use_count[cpu][cluster] != 2) { + /* + * The only possible values are: + * 0 = CPU down + * 1 = CPU (still) up + * 2 = CPU requested to be up before it had a chance + * to actually make itself down. + * Any other value is a bug. + */ + BUG(); } - rst_hold &= ~(cpumask | (cpumask << 4)); - writel(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); arch_spin_unlock(&dcscb_lock); local_irq_enable(); @@ -78,7 +92,8 @@ static int dcscb_power_up(unsigned int cpu, unsigned int cluster) static void dcscb_power_down(void) { - unsigned int mpidr, cpu, cluster, rst_hold, cpumask, last_man; + unsigned int mpidr, cpu, cluster, rst_hold, cpumask; + bool last_man = false, skip_wfi = false; mpidr = read_cpuid_mpidr(); cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); @@ -89,13 +104,26 @@ static void dcscb_power_down(void) BUG_ON(cpu >= 4 || cluster >= 2); arch_spin_lock(&dcscb_lock); - rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); - rst_hold |= cpumask; - if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf) - rst_hold |= (1 << 8); - writel(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + dcscb_use_count[cpu][cluster]--; + if (dcscb_use_count[cpu][cluster] == 0) { + rst_hold = readl_relaxed(dcscb_base + RST_HOLD0 + cluster * 4); + rst_hold |= cpumask; + if (((rst_hold | (rst_hold >> 4)) & 0xf) == 0xf) { + rst_hold |= (1 << 8); + last_man = true; + } + writel(rst_hold, dcscb_base + RST_HOLD0 + cluster * 4); + } else if (dcscb_use_count[cpu][cluster] == 1) { + /* + * A power_up request went ahead of us. + * Even if we do not want to shut this CPU down, + * the caller expects a certain state as if the WFI + * was aborted. So let's continue with cache cleaning. + */ + skip_wfi = true; + } else + BUG(); arch_spin_unlock(&dcscb_lock); - last_man = (rst_hold & (1 << 8)); /* * Now let's clean our L1 cache and shut ourself down. @@ -122,8 +150,10 @@ static void dcscb_power_down(void) set_auxcr(get_auxcr() & ~(1 << 6)); /* Now we are prepared for power-down, do it: */ - dsb(); - wfi(); + if (!skip_wfi) { + dsb(); + wfi(); + } /* Not dead at this point? Let our caller cope. */ } @@ -133,6 +163,19 @@ static const struct mcpm_platform_ops dcscb_power_ops = { .power_down = dcscb_power_down, }; +static void __init dcscb_usage_count_init(void) +{ + unsigned int mpidr, cpu, cluster; + + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); + BUG_ON(cpu >= 4 || cluster >= 2); + dcscb_use_count[cpu][cluster] = 1; +} + static int __init dcscb_init(void) { int ret; @@ -141,6 +184,8 @@ static int __init dcscb_init(void) if (!dcscb_base) return -EADDRNOTAVAIL; + dcscb_usage_count_init(); + ret = mcpm_platform_register(&dcscb_power_ops); if (ret) { iounmap(dcscb_base);