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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by CY4PEPF0000EE3E.mail.protection.outlook.com (10.167.242.18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7025.12 via Frontend Transport; Mon, 20 Nov 2023 14:16:20 +0000 Received: from AUS-P9-MLIMONCI.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Mon, 20 Nov 2023 08:16:18 -0600 From: Mario Limonciello To: =?utf-8?q?Mateusz_Jo=C5=84czyk?= , Alessandro Zummo , Alexandre Belloni CC: "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" , open list , , , , , , , , "Mario Limonciello" Subject: [PATCH v2 3/4] rtc: Add support for configuring the UIP timeout for RTC reads Date: Mon, 20 Nov 2023 08:15:54 -0600 Message-ID: <20231120141555.458-4-mario.limonciello@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231120141555.458-1-mario.limonciello@amd.com> References: <20231120141555.458-1-mario.limonciello@amd.com> Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000EE3E:EE_|PH8PR12MB7376:EE_ X-MS-Office365-Filtering-Correlation-Id: e92f08f4-55fa-4f48-9611-08dbe9d344ac X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Nov 2023 14:16:20.1495 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e92f08f4-55fa-4f48-9611-08dbe9d344ac X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000EE3E.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB7376 The UIP timeout is hardcoded to 10ms for all RTC reads, but in some contexts this might not be enough time. Add a timeout parameter to mc146818_get_time() and mc146818_get_time_callback(). If UIP timeout is configured by caller to be >=100 ms and a call takes this long, log a warning. Make all callers use 10ms to ensure no functional changes. Cc: stable@vger.kernel.org # 6.1.y: commit d2a632a8a117 ("rtc: mc146818-lib: reduce RTC_UIP polling period") Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") Signed-off-by: Mario Limonciello --- v1->v2: * Add a warning if 100ms or more * Add stable and fixes tags --- arch/alpha/kernel/rtc.c | 2 +- arch/x86/kernel/hpet.c | 2 +- arch/x86/kernel/rtc.c | 2 +- drivers/base/power/trace.c | 2 +- drivers/rtc/rtc-cmos.c | 6 +++--- drivers/rtc/rtc-mc146818-lib.c | 35 ++++++++++++++++++++++++++-------- include/linux/mc146818rtc.h | 3 ++- 7 files changed, 36 insertions(+), 16 deletions(-) diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c index fb3025396ac9..cfdf90bc8b3f 100644 --- a/arch/alpha/kernel/rtc.c +++ b/arch/alpha/kernel/rtc.c @@ -80,7 +80,7 @@ init_rtc_epoch(void) static int alpha_rtc_read_time(struct device *dev, struct rtc_time *tm) { - int ret = mc146818_get_time(tm); + int ret = mc146818_get_time(tm, 10); if (ret < 0) { dev_err_ratelimited(dev, "unable to read current time\n"); diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 41eecf180b7f..17adad4cbe78 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -1438,7 +1438,7 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id) memset(&curr_time, 0, sizeof(struct rtc_time)); if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) { - if (unlikely(mc146818_get_time(&curr_time) < 0)) { + if (unlikely(mc146818_get_time(&curr_time, 10) < 0)) { pr_err_ratelimited("unable to read current time from RTC\n"); return IRQ_HANDLED; } diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 1309b9b05338..961ebc7f1872 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -67,7 +67,7 @@ void mach_get_cmos_time(struct timespec64 *now) return; } - if (mc146818_get_time(&tm)) { + if (mc146818_get_time(&tm, 10)) { pr_err("Unable to read current time from RTC\n"); now->tv_sec = now->tv_nsec = 0; return; diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c index 72b7a92337b1..c2e925357474 100644 --- a/drivers/base/power/trace.c +++ b/drivers/base/power/trace.c @@ -120,7 +120,7 @@ static unsigned int read_magic_time(void) struct rtc_time time; unsigned int val; - if (mc146818_get_time(&time) < 0) { + if (mc146818_get_time(&time, 10) < 0) { pr_err("Unable to read current time from RTC\n"); return 0; } diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 391f91d3d144..d278b085821e 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -231,7 +231,7 @@ static int cmos_read_time(struct device *dev, struct rtc_time *t) if (!pm_trace_rtc_valid()) return -EIO; - ret = mc146818_get_time(t); + ret = mc146818_get_time(t, 10); if (ret < 0) { dev_err_ratelimited(dev, "unable to read current time\n"); return ret; @@ -307,7 +307,7 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t) * * Use the mc146818_avoid_UIP() function to avoid this. */ - if (!mc146818_avoid_UIP(cmos_read_alarm_callback, &p)) + if (!mc146818_avoid_UIP(cmos_read_alarm_callback, 10, &p)) return -EIO; if (!(p.rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { @@ -556,7 +556,7 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t) * * Use mc146818_avoid_UIP() to avoid this. */ - if (!mc146818_avoid_UIP(cmos_set_alarm_callback, &p)) + if (!mc146818_avoid_UIP(cmos_set_alarm_callback, 10, &p)) return -ETIMEDOUT; cmos->alarm_expires = rtc_tm_to_time64(&t->time); diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index 43a28e82674e..5abb925da4fa 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -8,26 +8,30 @@ #include #endif +#define UIP_RECHECK_DELAY 100 /* usec */ +#define UIP_RECHECK_TIMEOUT_MS(x) (USEC_PER_MSEC / UIP_RECHECK_DELAY * x) + /* * Execute a function while the UIP (Update-in-progress) bit of the RTC is - * unset. + * unset. The timeout is configurable by the caller in ms. * * Warning: callback may be executed more then once. */ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), + int timeout, void *param) { int i; unsigned long flags; unsigned char seconds; - for (i = 0; i < 100; i++) { + for (i = 0; i < UIP_RECHECK_TIMEOUT_MS(timeout); i++) { spin_lock_irqsave(&rtc_lock, flags); /* * Check whether there is an update in progress during which the * readout is unspecified. The maximum update time is ~2ms. Poll - * every 100 usec for completion. + * for completion. * * Store the second value before checking UIP so a long lasting * NMI which happens to hit after the UIP check cannot make @@ -37,7 +41,7 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { spin_unlock_irqrestore(&rtc_lock, flags); - udelay(100); + udelay(UIP_RECHECK_DELAY); continue; } @@ -56,7 +60,7 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), */ if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { spin_unlock_irqrestore(&rtc_lock, flags); - udelay(100); + udelay(UIP_RECHECK_DELAY); continue; } @@ -72,6 +76,9 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), } spin_unlock_irqrestore(&rtc_lock, flags); + if (i >= UIP_RECHECK_TIMEOUT_MS(100)) + pr_warn("RTC took %d iterations to clear UIP\n", i); + return true; } return false; @@ -84,7 +91,7 @@ EXPORT_SYMBOL_GPL(mc146818_avoid_UIP); */ bool mc146818_does_rtc_work(void) { - return mc146818_avoid_UIP(NULL, NULL); + return mc146818_avoid_UIP(NULL, 10, NULL); } EXPORT_SYMBOL_GPL(mc146818_does_rtc_work); @@ -130,13 +137,25 @@ static void mc146818_get_time_callback(unsigned char seconds, void *param_in) p->ctrl = CMOS_READ(RTC_CONTROL); } -int mc146818_get_time(struct rtc_time *time) +/** + * mc146818_get_time - Get the current time from the RTC + * @time: pointer to struct rtc_time to store the current time + * @timeout: timeout value in ms + * + * This function reads the current time from the RTC and stores it in the + * provided struct rtc_time. The timeout parameter specifies the maximum + * time to wait for the RTC to become ready. + * + * Return: 0 on success, -ETIMEDOUT if the RTC did not become ready within + * the specified timeout, or another error code if an error occurred. + */ +int mc146818_get_time(struct rtc_time *time, int timeout) { struct mc146818_get_time_callback_param p = { .time = time }; - if (!mc146818_avoid_UIP(mc146818_get_time_callback, &p)) { + if (!mc146818_avoid_UIP(mc146818_get_time_callback, timeout, &p)) { memset(time, 0, sizeof(*time)); return -ETIMEDOUT; } diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h index b0da04fe087b..34dfcc77f505 100644 --- a/include/linux/mc146818rtc.h +++ b/include/linux/mc146818rtc.h @@ -126,10 +126,11 @@ struct cmos_rtc_board_info { #endif /* ARCH_RTC_LOCATION */ bool mc146818_does_rtc_work(void); -int mc146818_get_time(struct rtc_time *time); +int mc146818_get_time(struct rtc_time *time, int timeout); int mc146818_set_time(struct rtc_time *time); bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), + int timeout, void *param); #endif /* _MC146818RTC_H */