From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:37544 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753050AbeDKS7z (ORCPT ); Wed, 11 Apr 2018 14:59:55 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gary Bisson , Alexandre Belloni , Sasha Levin Subject: [PATCH 4.9 160/310] rtc: m41t80: fix SQW dividers override when setting a date Date: Wed, 11 Apr 2018 20:34:59 +0200 Message-Id: <20180411183629.277414543@linuxfoundation.org> In-Reply-To: <20180411183622.305902791@linuxfoundation.org> References: <20180411183622.305902791@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gary Bisson [ Upstream commit 0f546b058b86ea2f661cc7a6e931cee5a29959ef ] This patch is only relevant for RTC with the SQ_ALT feature which means the clock output frequency divider is stored in the weekday register. Current implementation discards the previous dividers value and clear them as soon as the time is set. Signed-off-by: Gary Bisson Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/rtc/rtc-m41t80.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -168,6 +168,7 @@ static int m41t80_get_datetime(struct i2 /* Sets the given date and time to the real time clock. */ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) { + struct m41t80_data *clientdata = i2c_get_clientdata(client); unsigned char buf[8]; int err, flags; @@ -183,6 +184,17 @@ static int m41t80_set_datetime(struct i2 buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100); buf[M41T80_REG_WDAY] = tm->tm_wday; + /* If the square wave output is controlled in the weekday register */ + if (clientdata->features & M41T80_FEATURE_SQ_ALT) { + int val; + + val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY); + if (val < 0) + return val; + + buf[M41T80_REG_WDAY] |= (val & 0xf0); + } + err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC, sizeof(buf), buf); if (err < 0) {