From patchwork Wed Apr 19 16:44:24 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 97652 Delivered-To: patch@linaro.org Received: by 10.182.246.10 with SMTP id xs10csp355045obc; Wed, 19 Apr 2017 09:45:43 -0700 (PDT) X-Received: by 10.84.230.131 with SMTP id e3mr5131838plk.100.1492620343847; Wed, 19 Apr 2017 09:45:43 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id z62si3255932pgd.263.2017.04.19.09.45.43; Wed, 19 Apr 2017 09:45:43 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966686AbdDSQpf (ORCPT + 16 others); Wed, 19 Apr 2017 12:45:35 -0400 Received: from foss.arm.com ([217.140.101.70]:43664 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966636AbdDSQpZ (ORCPT ); Wed, 19 Apr 2017 12:45:25 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B99A61A09; Wed, 19 Apr 2017 09:45:19 -0700 (PDT) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 51EFA3F4FF; Wed, 19 Apr 2017 09:45:18 -0700 (PDT) From: Mark Rutland To: daniel.lezcano@linaro.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tglx@linutronix.de, fu.wei@linaro.org, lorenzo.pieralisi@arm.com, hanjun.guo@linaro.org, marc.zyngier@arm.com Subject: [PATCH 07/16] clocksource: arm_arch_timer: split dt-only rate handling Date: Wed, 19 Apr 2017 17:44:24 +0100 Message-Id: <1492620273-30037-8-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1492620273-30037-1-git-send-email-mark.rutland@arm.com> References: <1492620273-30037-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fu Wei For historical reasons, rate detection when probing via DT is somewhat convoluted. We tried to package this up in arch_timer_detect_rate(), but with the addition of ACPI worse, and gets in the way of stringent rate checking when ACPI is used. This patch makes arch_timer_detect_rate() specific to DT, ripping out ACPI logic. In preparation for rework of the MMIO timer probing, the reading of the relevant CNTFRQ register is factored out to callers. The function is then renamed to arch_timer_of_configure_rate(), which better represents its new place in the world. Comments are added in the DT and ACPI probe paths to explain this. Signed-off-by: Fu Wei [Mark: reword commit message] Signed-off-by: Mark Rutland --- drivers/clocksource/arm_arch_timer.c | 41 ++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 18 deletions(-) -- 1.9.1 diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 94de018..02c5cb8 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -818,24 +818,19 @@ static int arch_timer_starting_cpu(unsigned int cpu) return 0; } -static void -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) +/* + * For historical reasons, when probing with DT we use whichever (non-zero) + * rate was probed first, and don't verify that others match. If the first node + * probed has a clock-frequency property, this overrides the HW register. + */ +static void arch_timer_of_configure_rate(u32 rate, struct device_node *np) { /* Who has more than one independent system counter? */ if (arch_timer_rate) return; - /* - * Try to determine the frequency from the device tree or CNTFRQ, - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. - */ - if (!acpi_disabled || - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { - if (cntbase) - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); - else - arch_timer_rate = arch_timer_get_cntfrq(); - } + if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_rate = rate; /* Check the timer frequency. */ if (arch_timer_rate == 0) @@ -1166,6 +1161,7 @@ static int __init arch_timer_init(void) static int __init arch_timer_of_init(struct device_node *np) { int i; + u32 rate; if (arch_timers_present & ARCH_TIMER_TYPE_CP15) { pr_warn("multiple nodes in dt, skipping\n"); @@ -1176,7 +1172,8 @@ static int __init arch_timer_of_init(struct device_node *np) for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) arch_timer_ppi[i] = irq_of_parse_and_map(np, i); - arch_timer_detect_rate(NULL, np); + rate = arch_timer_get_cntfrq; + arch_timer_of_configure_rate(rate, np); arch_timer_c3stop = !of_property_read_bool(np, "always-on"); @@ -1212,7 +1209,7 @@ static int __init arch_timer_mem_init(struct device_node *np) struct device_node *frame, *best_frame = NULL; void __iomem *cntctlbase, *base; unsigned int irq, ret = -EINVAL; - u32 cnttidr; + u32 cnttidr, rate; arch_timers_present |= ARCH_TIMER_TYPE_MEM; cntctlbase = of_iomap(np, 0); @@ -1278,7 +1275,8 @@ static int __init arch_timer_mem_init(struct device_node *np) goto out; } - arch_timer_detect_rate(base, np); + rate = readl(base + CNTFRQ); + arch_timer_of_configure_rate(rate, np); ret = arch_timer_mem_register(base, irq); if (ret) goto out; @@ -1339,8 +1337,15 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table) map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt, gtdt->non_secure_el2_flags); - /* Get the frequency from CNTFRQ */ - arch_timer_detect_rate(NULL, NULL); + /* + * When probing via ACPI, we have no mechanism to override the sysreg + * CNTFRQ value. This *must* be correct. + */ + arch_timer_rate = arch_timer_get_cntfrq(); + if (!arch_timer_rate) { + pr_err(FW_BUG "frequency not available.\n"); + return -EINVAL; + } arch_timer_uses_ppi = arch_timer_select_ppi(); if (!arch_timer_ppi[arch_timer_uses_ppi]) {