From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F646C4332F for ; Wed, 22 Sep 2021 21:20:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A3A160EDF for ; Wed, 22 Sep 2021 21:20:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238114AbhIVVVq (ORCPT ); Wed, 22 Sep 2021 17:21:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:40544 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238015AbhIVVVZ (ORCPT ); Wed, 22 Sep 2021 17:21:25 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7AC51611C6; Wed, 22 Sep 2021 21:19:55 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mT9ej-00CPSk-Rr; Wed, 22 Sep 2021 22:19:53 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Mark Rutland , Daniel Lezcano , Thomas Gleixner , Peter Shier , Raghavendra Rao Ananta , Ricardo Koller , Oliver Upton , Will Deacon , Catalin Marinas , Linus Walleij , kernel-team@android.com Subject: [PATCH v2 09/16] clocksource/arm_arch_timer: Work around broken CVAL implementations Date: Wed, 22 Sep 2021 22:19:34 +0100 Message-Id: <20210922211941.2756270-10-maz@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210922211941.2756270-1-maz@kernel.org> References: <20210922211941.2756270-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, daniel.lezcano@linaro.org, tglx@linutronix.de, pshier@google.com, rananta@google.com, ricarkol@google.com, oupton@google.com, will@kernel.org, catalin.marinas@arm.com, linus.walleij@linaro.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The Applied Micro XGene-1 SoC has a busted implementation of the CVAL register: it looks like it is based on TVAL instead of the other way around. The net effect of this implementation blunder is that the maximum deadline you can program in the timer is 32bit wide. Use a MIDR check to notice the broken CPU, and reduce the width of the timer to 32bit. Signed-off-by: Marc Zyngier --- drivers/clocksource/arm_arch_timer.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 36e091412151..ef3f83865dcd 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -780,9 +780,32 @@ static int arch_timer_set_next_event_phys_mem(unsigned long evt, return 0; } +static u64 __arch_timer_check_delta(void) +{ +#ifdef CONFIG_ARM64 + const struct midr_range broken_cval_midrs[] = { + /* + * XGene-1 implements CVAL in terms of TVAL, meaning + * that the maximum timer range is 32bit. Shame on them. + */ + MIDR_ALL_VERSIONS(MIDR_CPU_MODEL(ARM_CPU_IMP_APM, + APM_CPU_PART_POTENZA)), + {}, + }; + + if (is_midr_in_range_list(read_cpuid_id(), broken_cval_midrs)) { + pr_warn_once("Broken CNTx_CVAL_EL1, limiting width to 32bits"); + return CLOCKSOURCE_MASK(32); + } +#endif + return CLOCKSOURCE_MASK(56); +} + static void __arch_timer_setup(unsigned type, struct clock_event_device *clk) { + u64 max_delta; + clk->features = CLOCK_EVT_FEAT_ONESHOT; if (type == ARCH_TIMER_TYPE_CP15) { @@ -814,6 +837,7 @@ static void __arch_timer_setup(unsigned type, } clk->set_next_event = sne; + max_delta = __arch_timer_check_delta(); } else { clk->features |= CLOCK_EVT_FEAT_DYNIRQ; clk->name = "arch_mem_timer"; @@ -830,11 +854,13 @@ static void __arch_timer_setup(unsigned type, clk->set_next_event = arch_timer_set_next_event_phys_mem; } + + max_delta = CLOCKSOURCE_MASK(56); } clk->set_state_shutdown(clk); - clockevents_config_and_register(clk, arch_timer_rate, 0xf, CLOCKSOURCE_MASK(56)); + clockevents_config_and_register(clk, arch_timer_rate, 0xf, max_delta); } static void arch_timer_evtstrm_enable(int divider) -- 2.30.2