From patchwork Mon Feb 6 16:47:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 93467 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp1785037qgi; Mon, 6 Feb 2017 08:49:05 -0800 (PST) X-Received: by 10.98.89.195 with SMTP id k64mr14088952pfj.126.1486399745312; Mon, 06 Feb 2017 08:49:05 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id i12si1190029plk.122.2017.02.06.08.49.05; Mon, 06 Feb 2017 08:49:05 -0800 (PST) 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 S1752207AbdBFQtD (ORCPT + 25 others); Mon, 6 Feb 2017 11:49:03 -0500 Received: from foss.arm.com ([217.140.101.70]:34534 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919AbdBFQs7 (ORCPT ); Mon, 6 Feb 2017 11:48:59 -0500 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 E617114F6; Mon, 6 Feb 2017 08:48:53 -0800 (PST) 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 C149C3F458; Mon, 6 Feb 2017 08:48:52 -0800 (PST) From: Mark Rutland To: daniel.lezcano@linaro.org Cc: tglx@linutronix.de, mark.rutland@arm.com, marc.zyngier@arm.com, dingtianhong@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/4] arm64: arch_timer: add dt binding for hisilicon-161010101 erratum Date: Mon, 6 Feb 2017 16:47:39 +0000 Message-Id: <1486399662-17601-2-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1486399662-17601-1-git-send-email-mark.rutland@arm.com> References: <1486399662-17601-1-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: Ding Tianhong This erratum describes a bug in logic outside the core, so MIDR can't be used to identify its presence, and reading an SoC-specific revision register from common arch timer code would be awkward. So, describe it in the device tree. Signed-off-by: Ding Tianhong Acked-by: Rob Herring Signed-off-by: Mark Rutland --- Documentation/devicetree/bindings/arm/arch_timer.txt | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.9.1 diff --git a/Documentation/devicetree/bindings/arm/arch_timer.txt b/Documentation/devicetree/bindings/arm/arch_timer.txt index ad440a2..e926aea 100644 --- a/Documentation/devicetree/bindings/arm/arch_timer.txt +++ b/Documentation/devicetree/bindings/arm/arch_timer.txt @@ -31,6 +31,12 @@ to deliver its interrupts via SPIs. This also affects writes to the tval register, due to the implicit counter read. +- hisilicon,erratum-161010101 : A boolean property. Indicates the + presence of Hisilicon erratum 161010101, which says that reading the + counters is unreliable in some cases, and reads may return a value 32 + beyond the correct value. This also affects writes to the tval + registers, due to the implicit counter read. + ** Optional properties: - arm,cpu-registers-not-fw-configured : Firmware does not initialize From patchwork Mon Feb 6 16:47:40 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 93466 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp1785008qgi; Mon, 6 Feb 2017 08:49:01 -0800 (PST) X-Received: by 10.98.74.84 with SMTP id x81mr14076926pfa.172.1486399741040; Mon, 06 Feb 2017 08:49:01 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id m2si1175211plk.231.2017.02.06.08.49.00; Mon, 06 Feb 2017 08:49:01 -0800 (PST) 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 S1751603AbdBFQs6 (ORCPT + 25 others); Mon, 6 Feb 2017 11:48:58 -0500 Received: from foss.arm.com ([217.140.101.70]:34542 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbdBFQs4 (ORCPT ); Mon, 6 Feb 2017 11:48:56 -0500 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 945A4152D; Mon, 6 Feb 2017 08:48:55 -0800 (PST) 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 6F2AE3F458; Mon, 6 Feb 2017 08:48:54 -0800 (PST) From: Mark Rutland To: daniel.lezcano@linaro.org Cc: tglx@linutronix.de, mark.rutland@arm.com, marc.zyngier@arm.com, dingtianhong@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/4] arm64: arm_arch_timer: remove fsl-a008585 parameter Date: Mon, 6 Feb 2017 16:47:40 +0000 Message-Id: <1486399662-17601-3-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1486399662-17601-1-git-send-email-mark.rutland@arm.com> References: <1486399662-17601-1-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: Ding Tianhong Having a command line option to flip the errata handling for a particular erratum is a little bit unusual, and it's vastly superior to pass this in the DT. By common consensus, it's best to kill off the command line parameter. Signed-off-by: Ding Tianhong [Mark: split patch, reword commit message] Signed-off-by: Mark Rutland Acked-by: Daniel Lezcano --- Documentation/admin-guide/kernel-parameters.txt | 9 --------- drivers/clocksource/arm_arch_timer.c | 14 -------------- 2 files changed, 23 deletions(-) -- 1.9.1 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index be7c0d9..d8fc55a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -549,15 +549,6 @@ loops can be debugged more effectively on production systems. - clocksource.arm_arch_timer.fsl-a008585= - [ARM64] - Format: - Enable/disable the workaround of Freescale/NXP - erratum A-008585. This can be useful for KVM - guests, if the guest device tree doesn't show the - erratum. If unspecified, the workaround is - enabled based on the device tree. - clearcpuid=BITNUM [X86] Disable CPUID feature X for the kernel. See arch/x86/include/asm/cpufeatures.h for the valid bit diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 4c8c3fb..6a9d031 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -101,20 +101,6 @@ static int __init early_evtstrm_cfg(char *buf) static int fsl_a008585_enable = -1; -static int __init early_fsl_a008585_cfg(char *buf) -{ - int ret; - bool val; - - ret = strtobool(buf, &val); - if (ret) - return ret; - - fsl_a008585_enable = val; - return 0; -} -early_param("clocksource.arm_arch_timer.fsl-a008585", early_fsl_a008585_cfg); - u32 __fsl_a008585_read_cntp_tval_el0(void) { return __fsl_a008585_read_reg(cntp_tval_el0); From patchwork Mon Feb 6 16:47:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 93468 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp1785113qgi; Mon, 6 Feb 2017 08:49:16 -0800 (PST) X-Received: by 10.99.45.3 with SMTP id t3mr14517037pgt.162.1486399756245; Mon, 06 Feb 2017 08:49:16 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id c21si1189987pgi.128.2017.02.06.08.49.15; Mon, 06 Feb 2017 08:49:16 -0800 (PST) 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 S1752252AbdBFQtJ (ORCPT + 25 others); Mon, 6 Feb 2017 11:49:09 -0500 Received: from foss.arm.com ([217.140.101.70]:34558 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbdBFQtC (ORCPT ); Mon, 6 Feb 2017 11:49:02 -0500 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 516141576; Mon, 6 Feb 2017 08:48:57 -0800 (PST) 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 290153F458; Mon, 6 Feb 2017 08:48:56 -0800 (PST) From: Mark Rutland To: daniel.lezcano@linaro.org Cc: tglx@linutronix.de, mark.rutland@arm.com, marc.zyngier@arm.com, dingtianhong@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 3/4] arm64: arch_timer: introduce generic errata handling infrastructure Date: Mon, 6 Feb 2017 16:47:41 +0000 Message-Id: <1486399662-17601-4-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1486399662-17601-1-git-send-email-mark.rutland@arm.com> References: <1486399662-17601-1-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: Ding Tianhong Currently we have code inline in the arch timer probe path to cater for Freescale erratum A-008585, complete with ifdeffery. This is a little ugly, and will get worse as we try to add more errata handling. This patch refactors the handling of Freescale erratum A-008585. Now the erratum is described in a generic arch_timer_erratum_workaround structure, and the probe path can iterate over these to detect errata and enable workarounds. This will simplify the addition and maintenance of code handling Hisilicon erratum 161010101. Signed-off-by: Ding Tianhong [Mark: split patch, correct Kconfig, reword commit message] Signed-off-by: Mark Rutland Acked-by: Daniel Lezcano --- arch/arm64/include/asm/arch_timer.h | 38 +++++---------- drivers/clocksource/Kconfig | 4 ++ drivers/clocksource/arm_arch_timer.c | 92 ++++++++++++++++++++++++------------ 3 files changed, 80 insertions(+), 54 deletions(-) -- 1.9.1 diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index eaa5bbe..b4b3400 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -29,41 +29,29 @@ #include -#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585) +#if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND) extern struct static_key_false arch_timer_read_ool_enabled; -#define needs_fsl_a008585_workaround() \ +#define needs_unstable_timer_counter_workaround() \ static_branch_unlikely(&arch_timer_read_ool_enabled) #else -#define needs_fsl_a008585_workaround() false +#define needs_unstable_timer_counter_workaround() false #endif -u32 __fsl_a008585_read_cntp_tval_el0(void); -u32 __fsl_a008585_read_cntv_tval_el0(void); -u64 __fsl_a008585_read_cntvct_el0(void); -/* - * The number of retries is an arbitrary value well beyond the highest number - * of iterations the loop has been observed to take. - */ -#define __fsl_a008585_read_reg(reg) ({ \ - u64 _old, _new; \ - int _retries = 200; \ - \ - do { \ - _old = read_sysreg(reg); \ - _new = read_sysreg(reg); \ - _retries--; \ - } while (unlikely(_old != _new) && _retries); \ - \ - WARN_ON_ONCE(!_retries); \ - _new; \ -}) +struct arch_timer_erratum_workaround { + const char *id; /* Indicate the Erratum ID */ + u32 (*read_cntp_tval_el0)(void); + u32 (*read_cntv_tval_el0)(void); + u64 (*read_cntvct_el0)(void); +}; + +extern const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround; #define arch_timer_reg_read_stable(reg) \ ({ \ u64 _val; \ - if (needs_fsl_a008585_workaround()) \ - _val = __fsl_a008585_read_##reg(); \ + if (needs_unstable_timer_counter_workaround()) \ + _val = timer_unstable_counter_workaround->read_##reg();\ else \ _val = read_sysreg(reg); \ _val; \ diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 4866f7a..e132bb3 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -325,10 +325,14 @@ config ARM_ARCH_TIMER_EVTSTREAM This must be disabled for hardware validation purposes to detect any hardware anomalies of missing events. +config ARM_ARCH_TIMER_OOL_WORKAROUND + bool + config FSL_ERRATUM_A008585 bool "Workaround for Freescale/NXP Erratum A-008585" default y depends on ARM_ARCH_TIMER && ARM64 + select ARM_ARCH_TIMER_OOL_WORKAROUND help This option enables a workaround for Freescale/NXP Erratum A-008585 ("ARM generic timer may contain an erroneous diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 6a9d031..2af0739 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -96,27 +96,58 @@ static int __init early_evtstrm_cfg(char *buf) */ #ifdef CONFIG_FSL_ERRATUM_A008585 -DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled); -EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled); - -static int fsl_a008585_enable = -1; - -u32 __fsl_a008585_read_cntp_tval_el0(void) +/* + * The number of retries is an arbitrary value well beyond the highest number + * of iterations the loop has been observed to take. + */ +#define __fsl_a008585_read_reg(reg) ({ \ + u64 _old, _new; \ + int _retries = 200; \ + \ + do { \ + _old = read_sysreg(reg); \ + _new = read_sysreg(reg); \ + _retries--; \ + } while (unlikely(_old != _new) && _retries); \ + \ + WARN_ON_ONCE(!_retries); \ + _new; \ +}) + +static u32 notrace fsl_a008585_read_cntp_tval_el0(void) { return __fsl_a008585_read_reg(cntp_tval_el0); } -u32 __fsl_a008585_read_cntv_tval_el0(void) +static u32 notrace fsl_a008585_read_cntv_tval_el0(void) { return __fsl_a008585_read_reg(cntv_tval_el0); } -u64 __fsl_a008585_read_cntvct_el0(void) +static u64 notrace fsl_a008585_read_cntvct_el0(void) { return __fsl_a008585_read_reg(cntvct_el0); } -EXPORT_SYMBOL(__fsl_a008585_read_cntvct_el0); -#endif /* CONFIG_FSL_ERRATUM_A008585 */ +#endif + +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND +const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL; +EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround); + +DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled); +EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled); + +static const struct arch_timer_erratum_workaround ool_workarounds[] = { +#ifdef CONFIG_FSL_ERRATUM_A008585 + { + .id = "fsl,erratum-a008585", + .read_cntp_tval_el0 = fsl_a008585_read_cntp_tval_el0, + .read_cntv_tval_el0 = fsl_a008585_read_cntv_tval_el0, + .read_cntvct_el0 = fsl_a008585_read_cntvct_el0, + }, +#endif +}; +#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */ static __always_inline void arch_timer_reg_write(int access, enum arch_timer_reg reg, u32 val, @@ -267,8 +298,8 @@ static __always_inline void set_next_event(const int access, unsigned long evt, arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk); } -#ifdef CONFIG_FSL_ERRATUM_A008585 -static __always_inline void fsl_a008585_set_next_event(const int access, +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND +static __always_inline void erratum_set_next_event_generic(const int access, unsigned long evt, struct clock_event_device *clk) { unsigned long ctrl; @@ -286,20 +317,20 @@ static __always_inline void fsl_a008585_set_next_event(const int access, arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk); } -static int fsl_a008585_set_next_event_virt(unsigned long evt, +static int erratum_set_next_event_virt(unsigned long evt, struct clock_event_device *clk) { - fsl_a008585_set_next_event(ARCH_TIMER_VIRT_ACCESS, evt, clk); + erratum_set_next_event_generic(ARCH_TIMER_VIRT_ACCESS, evt, clk); return 0; } -static int fsl_a008585_set_next_event_phys(unsigned long evt, +static int erratum_set_next_event_phys(unsigned long evt, struct clock_event_device *clk) { - fsl_a008585_set_next_event(ARCH_TIMER_PHYS_ACCESS, evt, clk); + erratum_set_next_event_generic(ARCH_TIMER_PHYS_ACCESS, evt, clk); return 0; } -#endif /* CONFIG_FSL_ERRATUM_A008585 */ +#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */ static int arch_timer_set_next_event_virt(unsigned long evt, struct clock_event_device *clk) @@ -329,16 +360,16 @@ static int arch_timer_set_next_event_phys_mem(unsigned long evt, return 0; } -static void fsl_a008585_set_sne(struct clock_event_device *clk) +static void erratum_workaround_set_sne(struct clock_event_device *clk) { -#ifdef CONFIG_FSL_ERRATUM_A008585 +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND if (!static_branch_unlikely(&arch_timer_read_ool_enabled)) return; if (arch_timer_uses_ppi == VIRT_PPI) - clk->set_next_event = fsl_a008585_set_next_event_virt; + clk->set_next_event = erratum_set_next_event_virt; else - clk->set_next_event = fsl_a008585_set_next_event_phys; + clk->set_next_event = erratum_set_next_event_phys; #endif } @@ -371,7 +402,7 @@ static void __arch_timer_setup(unsigned type, BUG(); } - fsl_a008585_set_sne(clk); + erratum_workaround_set_sne(clk); } else { clk->features |= CLOCK_EVT_FEAT_DYNIRQ; clk->name = "arch_mem_timer"; @@ -591,7 +622,7 @@ static void __init arch_counter_register(unsigned type) clocksource_counter.archdata.vdso_direct = true; -#ifdef CONFIG_FSL_ERRATUM_A008585 +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND /* * Don't use the vdso fastpath if errata require using * the out-of-line counter accessor. @@ -879,12 +910,15 @@ static int __init arch_timer_of_init(struct device_node *np) arch_timer_c3stop = !of_property_read_bool(np, "always-on"); -#ifdef CONFIG_FSL_ERRATUM_A008585 - if (fsl_a008585_enable < 0) - fsl_a008585_enable = of_property_read_bool(np, "fsl,erratum-a008585"); - if (fsl_a008585_enable) { - static_branch_enable(&arch_timer_read_ool_enabled); - pr_info("Enabling workaround for FSL erratum A-008585\n"); +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND + for (i = 0; i < ARRAY_SIZE(ool_workarounds); i++) { + if (of_property_read_bool(np, ool_workarounds[i].id)) { + timer_unstable_counter_workaround = &ool_workarounds[i]; + static_branch_enable(&arch_timer_read_ool_enabled); + pr_info("arch_timer: Enabling workaround for %s\n", + timer_unstable_counter_workaround->id); + break; + } } #endif From patchwork Mon Feb 6 16:47:42 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 93469 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp1785305qgi; Mon, 6 Feb 2017 08:49:45 -0800 (PST) X-Received: by 10.99.189.9 with SMTP id a9mr14223355pgf.190.1486399785127; Mon, 06 Feb 2017 08:49:45 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id f4si1194636plf.93.2017.02.06.08.49.44; Mon, 06 Feb 2017 08:49:45 -0800 (PST) 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 S1752133AbdBFQtB (ORCPT + 25 others); Mon, 6 Feb 2017 11:49:01 -0500 Received: from foss.arm.com ([217.140.101.70]:34568 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbdBFQs7 (ORCPT ); Mon, 6 Feb 2017 11:48:59 -0500 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 41A401596; Mon, 6 Feb 2017 08:48:59 -0800 (PST) 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 1D5973F458; Mon, 6 Feb 2017 08:48:57 -0800 (PST) From: Mark Rutland To: daniel.lezcano@linaro.org Cc: tglx@linutronix.de, mark.rutland@arm.com, marc.zyngier@arm.com, dingtianhong@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 4/4] arm64: arch_timer: work around Hisilicon erratum 161010101 Date: Mon, 6 Feb 2017 16:47:42 +0000 Message-Id: <1486399662-17601-5-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1486399662-17601-1-git-send-email-mark.rutland@arm.com> References: <1486399662-17601-1-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: Ding Tianhong Erratum Hisilicon-161010101 says that the ARM generic timer counter "has the potential to contain an erroneous value when the timer value changes". Accesses to TVAL (both read and write) are also affected due to the implicit counter read. Accesses to CVAL are not affected. The workaround is to reread the system count registers until the value of the second read is larger than the first one by less than 32, the system counter can be guaranteed not to return wrong value twice by back-to-back read and the error value is always larger than the correct one by 32. Writes to TVAL are replaced with an equivalent write to CVAL. Signed-off-by: Ding Tianhong [Mark: split patch, fix Kconfig, reword commit message] Signed-off-by: Mark Rutland Acked-by: Daniel Lezcano --- drivers/clocksource/Kconfig | 10 ++++++++ drivers/clocksource/arm_arch_timer.c | 49 ++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) -- 1.9.1 diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index e132bb3..17ee71c 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -339,6 +339,16 @@ config FSL_ERRATUM_A008585 value"). The workaround will only be active if the fsl,erratum-a008585 property is found in the timer node. +config HISILICON_ERRATUM_161010101 + bool "Workaround for Hisilicon Erratum 161010101" + default y + select ARM_ARCH_TIMER_OOL_WORKAROUND + depends on ARM_ARCH_TIMER && ARM64 + help + This option enables a workaround for Hisilicon Erratum + 161010101. The workaround will be active if the hisilicon,erratum-161010101 + property is found in the timer node. + config ARM_GLOBAL_TIMER bool "Support for the ARM global timer" if COMPILE_TEST select CLKSRC_OF if OF diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 2af0739..7b06aef 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -130,6 +130,47 @@ static u64 notrace fsl_a008585_read_cntvct_el0(void) } #endif +#ifdef CONFIG_HISILICON_ERRATUM_161010101 +/* + * Verify whether the value of the second read is larger than the first by + * less than 32 is the only way to confirm the value is correct, so clear the + * lower 5 bits to check whether the difference is greater than 32 or not. + * Theoretically the erratum should not occur more than twice in succession + * when reading the system counter, but it is possible that some interrupts + * may lead to more than twice read errors, triggering the warning, so setting + * the number of retries far beyond the number of iterations the loop has been + * observed to take. + */ +#define __hisi_161010101_read_reg(reg) ({ \ + u64 _old, _new; \ + int _retries = 50; \ + \ + do { \ + _old = read_sysreg(reg); \ + _new = read_sysreg(reg); \ + _retries--; \ + } while (unlikely((_new - _old) >> 5) && _retries); \ + \ + WARN_ON_ONCE(!_retries); \ + _new; \ +}) + +static u32 notrace hisi_161010101_read_cntp_tval_el0(void) +{ + return __hisi_161010101_read_reg(cntp_tval_el0); +} + +static u32 notrace hisi_161010101_read_cntv_tval_el0(void) +{ + return __hisi_161010101_read_reg(cntv_tval_el0); +} + +static u64 notrace hisi_161010101_read_cntvct_el0(void) +{ + return __hisi_161010101_read_reg(cntvct_el0); +} +#endif + #ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL; EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround); @@ -146,6 +187,14 @@ static u64 notrace fsl_a008585_read_cntvct_el0(void) .read_cntvct_el0 = fsl_a008585_read_cntvct_el0, }, #endif +#ifdef CONFIG_HISILICON_ERRATUM_161010101 + { + .id = "hisilicon,erratum-161010101", + .read_cntp_tval_el0 = hisi_161010101_read_cntp_tval_el0, + .read_cntv_tval_el0 = hisi_161010101_read_cntv_tval_el0, + .read_cntvct_el0 = hisi_161010101_read_cntvct_el0, + }, +#endif }; #endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */