From patchwork Mon Jan 4 18:31:24 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joshua Clayton X-Patchwork-Id: 562642 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from mail-qk0-x23b.google.com (mail-qk0-x23b.google.com [IPv6:2607:f8b0:400d:c09::23b]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id E06801402EC for ; Tue, 5 Jan 2016 05:31:45 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=googlegroups.com header.i=@googlegroups.com header.b=hyAcH1FI; dkim-atps=neutral Received: by mail-qk0-x23b.google.com with SMTP id p187sf99457526qkd.0 for ; Mon, 04 Jan 2016 10:31:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=20120806; h=mime-version:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references:x-original-sender :x-original-authentication-results:reply-to:content-type:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:sender:list-subscribe:list-unsubscribe; bh=KSPqBhkdjydq5t+lJ1ix/FaIi1jjSB9q8uFMnoG28Fs=; b=hyAcH1FIwwfthtIpcWkhffCwke8QYP/wz0F9A3YqitL69HNsMwFK6i3GevlHbKD1c9 LsIqn7uH3aOXSnZLkOzTNcXjfRIee/qIx6pCxp2Xjgsj0t/9TNN5qtbZo0WrvBkM7CYw pdCywp1TYbq3wRG1cJT6wZxEXKLLtQ0UmBs/nC8OohChriSbNIZd9aRfTk0VAcM+8uBi FTN+ZlHH/Td8rp4NlvgLBTcW9qyHoXM5tRtKW4tRm+GWtN8P9ZS6ts/i7SQWqwkZO+MP y6UJGQwoU1OjmIgKXpQZyZxgZhN3C2CfaGIxjiMDqNXYp/91fkGh3X1In0TtACMRY7gh EUQg== X-Received: by 10.182.142.7 with SMTP id rs7mr711332obb.2.1451932303993; Mon, 04 Jan 2016 10:31:43 -0800 (PST) MIME-Version: 1.0 X-BeenThere: rtc-linux@googlegroups.com Received: by 10.182.196.105 with SMTP id il9ls4027455obc.50.gmail; Mon, 04 Jan 2016 10:31:43 -0800 (PST) X-Received: by 10.182.63.17 with SMTP id c17mr17492840obs.7.1451932303758; Mon, 04 Jan 2016 10:31:43 -0800 (PST) Received: from mail-pf0-x241.google.com (mail-pf0-x241.google.com. [2607:f8b0:400e:c00::241]) by gmr-mx.google.com with ESMTPS id p88si8636056pfi.0.2016.01.04.10.31.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Jan 2016 10:31:43 -0800 (PST) Received-SPF: pass (google.com: domain of stillcompiling@gmail.com designates 2607:f8b0:400e:c00::241 as permitted sender) client-ip=2607:f8b0:400e:c00::241; Received: by mail-pf0-x241.google.com with SMTP id 78so20481790pfw.0 for ; Mon, 04 Jan 2016 10:31:43 -0800 (PST) X-Received: by 10.98.75.90 with SMTP id y87mr127227545pfa.94.1451932303651; Mon, 04 Jan 2016 10:31:43 -0800 (PST) Received: from localhost.localdomain (68-185-59-186.static.knwc.wa.charter.com. [68.185.59.186]) by smtp.gmail.com with ESMTPSA id 70sm72728356pfa.3.2016.01.04.10.31.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 04 Jan 2016 10:31:42 -0800 (PST) From: Joshua Clayton To: Alexandre Belloni , Alessandro Zummo Cc: rtc-linux@googlegroups.com, linux-kernel@vger.kernel.org, Joshua Clayton Subject: [rtc-linux] [PATCH v2 6/8] rtc: Add functions to set and read clock offset Date: Mon, 4 Jan 2016 10:31:24 -0800 Message-Id: X-Mailer: git-send-email 2.5.0 In-Reply-To: References: In-Reply-To: <0000-cover-letter.patch> References: <0000-cover-letter.patch> X-Original-Sender: stillcompiling@gmail.com X-Original-Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of stillcompiling@gmail.com designates 2607:f8b0:400e:c00::241 as permitted sender) smtp.mailfrom=stillcompiling@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Reply-To: rtc-linux@googlegroups.com Precedence: list Mailing-list: list rtc-linux@googlegroups.com; contact rtc-linux+owners@googlegroups.com List-ID: X-Spam-Checked-In-Group: rtc-linux@googlegroups.com X-Google-Group-Id: 712029733259 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , A number of rtc devices, such as the NXP pcf2123 include a facility to adjust the clock in order to compensate for temperature or a crystal, capacitor, etc, that results in the rtc clock not running at exactly 32.768 kHz. Data sheets I have seen refer to this as a clock offset, and measure it in parts per million (ppm), however they often reference ppm to 2 digits of precision, which makes integer ppm less than ideal. We use parts per billion, which more than covers the precision needed and works nicely within 32 bits Signed-off-by: Joshua Clayton --- drivers/rtc/interface.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/rtc.h | 4 ++++ 2 files changed, 61 insertions(+) diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index 5836751..57cd928 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -939,4 +939,61 @@ void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer) mutex_unlock(&rtc->ops_lock); } +/** + * rtc_read_offset - Read the amount of rtc offset in parts per billion + * @ rtc: rtc device to be used + * @ offset: the offset in parts per billion + * + * see below for details. + * + * Kernel interface to read rtc clock offset + * Returns 0 on success, or a negative number on error. + * If the rtc offset is not setable (or not implemented), return 0 and put + * 0 in the offset value; + */ +int rtc_read_offset(struct rtc_device *rtc, long *offset) +{ + int ret = 0; + + if (!rtc->ops) + return -ENODEV; + + if (!rtc->ops->set_offset) { + offset = 0; + return 0; + } + + mutex_lock(&rtc->ops_lock); + ret = rtc->ops->read_offset(rtc->dev.parent, offset); + mutex_unlock(&rtc->ops_lock); + return ret; +} +/** + * rtc_set_offset - Adjusts the duration of the average second + * @ rtc: rtc device to be used + * @ offset: the offset in parts per billion + * + * Some rtc's allow an adjustment to the average duration of a second + * to compensate for differences in the actual clock rate due to temperature, + * the crystal, capacitor, etc. + * + * Kernel interface to adjust an rtc clock offset. + * Return 0 on success, or a negative number on error. + * If the rtc offset is not setable (or not implemented), return -EINVAL + */ +int rtc_set_offset(struct rtc_device *rtc, long offset) +{ + int ret = 0; + + if (!rtc->ops) + return -ENODEV; + + if (!rtc->ops->set_offset) + return -EINVAL; + + mutex_lock(&rtc->ops_lock); + ret = rtc->ops->set_offset(rtc->dev.parent, offset); + mutex_unlock(&rtc->ops_lock); + return ret; +} diff --git a/include/linux/rtc.h b/include/linux/rtc.h index 3359f04..b693ada 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -89,6 +89,8 @@ struct rtc_class_ops { int (*set_mmss)(struct device *, unsigned long secs); int (*read_callback)(struct device *, int data); int (*alarm_irq_enable)(struct device *, unsigned int enabled); + int (*read_offset)(struct device *, long *offset); + int (*set_offset)(struct device *, long offset); }; #define RTC_DEVICE_NAME_SIZE 20 @@ -208,6 +210,8 @@ void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data); int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer, ktime_t expires, ktime_t period); void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer); +int rtc_read_offset(struct rtc_device *rtc, long *offset); +int rtc_set_offset(struct rtc_device *rtc, long offset); void rtc_timer_do_work(struct work_struct *work); static inline bool is_leap_year(unsigned int year)