From patchwork Wed Dec 21 10:28:16 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gregory CLEMENT X-Patchwork-Id: 9482849 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9E57A60487 for ; Wed, 21 Dec 2016 10:30:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98A162841B for ; Wed, 21 Dec 2016 10:30:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 89DEC2844B; Wed, 21 Dec 2016 10:30:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id DD7932841B for ; Wed, 21 Dec 2016 10:30:34 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1cJe8y-00040I-2P; Wed, 21 Dec 2016 10:29:08 +0000 Received: from mail.free-electrons.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1cJe8a-0003Xb-IZ for linux-arm-kernel@lists.infradead.org; Wed, 21 Dec 2016 10:28:49 +0000 Received: by mail.free-electrons.com (Postfix, from userid 110) id 9DC77206E8; Wed, 21 Dec 2016 11:28:24 +0100 (CET) Received: from localhost (83.146.29.93.rev.sfr.net [93.29.146.83]) by mail.free-electrons.com (Postfix) with ESMTPSA id 6AA4520693; Wed, 21 Dec 2016 11:28:24 +0100 (CET) From: Gregory CLEMENT To: Alessandro Zummo , Alexandre Belloni , rtc-linux@googlegroups.com Subject: [PATCH v3] rtc: armada38x: Follow the new recommendation for errata implementation Date: Wed, 21 Dec 2016 11:28:16 +0100 Message-Id: <20161221102816.6939-1-gregory.clement@free-electrons.com> X-Mailer: git-send-email 2.11.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161221_022845_381174_43A791F2 X-CRM114-Status: GOOD ( 21.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Petazzoni , Andrew Lunn , Jason Cooper , Haim Boot , Gregory CLEMENT , linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP According to RES-3124064: The device supports CPU write and read access to the RTC time register. However, due to this restriction, read and write from/to internal RTC register may fail. Workaround: General setup: 1. Configure the RTC Mbus Bridge Timing Control register (offset 0x184A0) to value 0xFD4D4FFF Write RTC WRCLK Period to its maximum value (0x3FF) Write RTC WRCLK setup to 0x29 Write RTC WRCLK High Time to 0x53 (default value) Write RTC Read Output Delay to its maximum value (0x1F) Mbus - Read All Byte Enable to 0x1 (default value) 2. Configure the RTC Test Configuration Register (offset 0xA381C) bit3 to '1' (Reserved, Marvell internal) For any RTC register read operation: 1. Read the requested register 100 times. 2. Find the result that appears most frequently and use this result as the correct value. For any RTC register write operation: 1. Issue two dummy writes of 0x0 to the RTC Status register (offset 0xA3800). 2. Write the time to the RTC Time register (offset 0xA380C). This patch is based on the work of Shaker Daibes Signed-off-by: Gregory CLEMENT --- Hi, this patch followed the patch series sent here: http://lists.infradead.org/pipermail/linux-arm-kernel/2016-December/473232.html For now I kept the patch 2 converting to time64_t apart after Russell King feedback. Changelog: v2 -> v3: - Removed unrelated change - Remove Unnecessary blank line - Used u32 instead of uint32_t - use the new errata name: RES-3124064 instead of FE-3124064 v1 -> v2: - merged the patch 1 and 3 - substantially modified the 1st patch with I think a better implementation: - First I do not put anymore more a big array onto the stack as suggested by Andrew Lunn. - Then I optimize the way to find the correct value. Gregory drivers/rtc/rtc-armada38x.c | 118 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 95 insertions(+), 23 deletions(-) diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c index 9a3f2a6f512e..6c9a2cbdc1a9 100644 --- a/drivers/rtc/rtc-armada38x.c +++ b/drivers/rtc/rtc-armada38x.c @@ -29,50 +29,118 @@ #define RTC_TIME 0xC #define RTC_ALARM1 0x10 +#define SOC_RTC_BRIDGE_TIMING_CTL 0x0 +#define SOC_RTC_PERIOD_OFFS 0 +#define SOC_RTC_PERIOD_MASK (0x3FF << SOC_RTC_PERIOD_OFFS) +#define SOC_RTC_READ_DELAY_OFFS 26 +#define SOC_RTC_READ_DELAY_MASK (0x1F << SOC_RTC_READ_DELAY_OFFS) + #define SOC_RTC_INTERRUPT 0x8 #define SOC_RTC_ALARM1 BIT(0) #define SOC_RTC_ALARM2 BIT(1) #define SOC_RTC_ALARM1_MASK BIT(2) #define SOC_RTC_ALARM2_MASK BIT(3) +#define SAMPLE_NR 100 + +struct value_to_freq { + u32 value; + u8 freq; +}; + struct armada38x_rtc { struct rtc_device *rtc_dev; void __iomem *regs; void __iomem *regs_soc; spinlock_t lock; int irq; + struct value_to_freq *val_to_freq; }; /* * According to the datasheet, the OS should wait 5us after every * register write to the RTC hard macro so that the required update * can occur without holding off the system bus + * According to errata RES-3124064, Write to any RTC register + * may fail. As a workaround, before writing to RTC + * register, issue a dummy write of 0x0 twice to RTC Status + * register. */ + static void rtc_delayed_write(u32 val, struct armada38x_rtc *rtc, int offset) { + writel(0, rtc->regs + RTC_STATUS); + writel(0, rtc->regs + RTC_STATUS); writel(val, rtc->regs + offset); udelay(5); } +/* Update RTC-MBUS bridge timing parameters */ +static void rtc_update_mbus_timing_params(struct armada38x_rtc *rtc) +{ + u32 reg; + + reg = readl(rtc->regs_soc + SOC_RTC_BRIDGE_TIMING_CTL); + reg &= ~SOC_RTC_PERIOD_MASK; + reg |= 0x3FF << SOC_RTC_PERIOD_OFFS; /* Maximum value */ + reg &= ~SOC_RTC_READ_DELAY_MASK; + reg |= 0x1F << SOC_RTC_READ_DELAY_OFFS; /* Maximum value */ + writel(reg, rtc->regs_soc + SOC_RTC_BRIDGE_TIMING_CTL); +} + +static u32 read_rtc_register_wa(struct armada38x_rtc *rtc, u8 rtc_reg) +{ + int i, index_max, max = 0; + + for (i = 0; i < SAMPLE_NR; i++) { + rtc->val_to_freq[i].value = readl(rtc->regs + rtc_reg); + rtc->val_to_freq[i].freq = 0; + } + + for (i = 0; i < SAMPLE_NR; i++) { + int j = 0; + u32 value = rtc->val_to_freq[i].value; + + while (rtc->val_to_freq[j].freq) { + if (rtc->val_to_freq[j].value == value) { + rtc->val_to_freq[j].freq++; + break; + } + j++; + } + + if (!rtc->val_to_freq[j].freq) { + rtc->val_to_freq[j].value = value; + rtc->val_to_freq[j].freq = 1; + } + + if (rtc->val_to_freq[j].freq > max) { + index_max = j; + max = rtc->val_to_freq[j].freq; + } + + /* + * If a value have already half of the sample this is + * the most frequent one and we can stop the research + * right now + */ + if (max > SAMPLE_NR / 2) + break; + } + + return rtc->val_to_freq[index_max].value; +} + static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm) { struct armada38x_rtc *rtc = dev_get_drvdata(dev); - unsigned long time, time_check, flags; + unsigned long time, flags; spin_lock_irqsave(&rtc->lock, flags); - time = readl(rtc->regs + RTC_TIME); - /* - * WA for failing time set attempts. As stated in HW ERRATA if - * more than one second between two time reads is detected - * then read once again. - */ - time_check = readl(rtc->regs + RTC_TIME); - if ((time_check - time) > 1) - time_check = readl(rtc->regs + RTC_TIME); - + time = read_rtc_register_wa(rtc, RTC_TIME); spin_unlock_irqrestore(&rtc->lock, flags); - rtc_time_to_tm(time_check, tm); + rtc_time_to_tm(time, tm); return 0; } @@ -87,16 +155,9 @@ static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm) if (ret) goto out; - /* - * According to errata FE-3124064, Write to RTC TIME register - * may fail. As a workaround, after writing to RTC TIME - * register, issue a dummy write of 0x0 twice to RTC Status - * register. - */ + spin_lock_irqsave(&rtc->lock, flags); rtc_delayed_write(time, rtc, RTC_TIME); - rtc_delayed_write(0, rtc, RTC_STATUS); - rtc_delayed_write(0, rtc, RTC_STATUS); spin_unlock_irqrestore(&rtc->lock, flags); out: @@ -111,8 +172,8 @@ static int armada38x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) spin_lock_irqsave(&rtc->lock, flags); - time = readl(rtc->regs + RTC_ALARM1); - val = readl(rtc->regs + RTC_IRQ1_CONF) & RTC_IRQ1_AL_EN; + time = read_rtc_register_wa(rtc, RTC_ALARM1); + val = read_rtc_register_wa(rtc, RTC_IRQ1_CONF) & RTC_IRQ1_AL_EN; spin_unlock_irqrestore(&rtc->lock, flags); @@ -182,7 +243,7 @@ static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data) val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT); writel(val & ~SOC_RTC_ALARM1, rtc->regs_soc + SOC_RTC_INTERRUPT); - val = readl(rtc->regs + RTC_IRQ1_CONF); + val = read_rtc_register_wa(rtc, RTC_IRQ1_CONF); /* disable all the interrupts for alarm 1 */ rtc_delayed_write(0, rtc, RTC_IRQ1_CONF); /* Ack the event */ @@ -221,6 +282,11 @@ static __init int armada38x_rtc_probe(struct platform_device *pdev) if (!rtc) return -ENOMEM; + rtc->val_to_freq = devm_kcalloc(&pdev->dev, SAMPLE_NR, + sizeof(struct value_to_freq), GFP_KERNEL); + if (!rtc->val_to_freq) + return -ENOMEM; + spin_lock_init(&rtc->lock); res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rtc"); @@ -253,6 +319,9 @@ static __init int armada38x_rtc_probe(struct platform_device *pdev) if (rtc->irq != -1) device_init_wakeup(&pdev->dev, 1); + /* Update RTC-MBUS bridge timing parameters */ + rtc_update_mbus_timing_params(rtc); + rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name, &armada38x_rtc_ops, THIS_MODULE); if (IS_ERR(rtc->rtc_dev)) { @@ -280,6 +349,9 @@ static int armada38x_rtc_resume(struct device *dev) if (device_may_wakeup(dev)) { struct armada38x_rtc *rtc = dev_get_drvdata(dev); + /* Update RTC-MBUS bridge timing parameters */ + rtc_update_mbus_timing_params(rtc); + return disable_irq_wake(rtc->irq); }