From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752527AbbDTX4G (ORCPT ); Mon, 20 Apr 2015 19:56:06 -0400 Received: from bear.ext.ti.com ([192.94.94.41]:47413 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbbDTX4D (ORCPT ); Mon, 20 Apr 2015 19:56:03 -0400 From: Nishanth Menon To: Alexandre Belloni , Alessandro Zummo CC: , , , Subject: [PATCH] drivers/rtc/rtc-ds1307.c: Enable the mcp794xx alarm after programming time Date: Mon, 20 Apr 2015 18:55:22 -0500 Message-ID: <1429574122-4284-1-git-send-email-nm@ti.com> X-Mailer: git-send-email 1.7.9.5 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Alarm interrupt enable register is at offset 0x7, while the time registers for the alarm follow that. When we program Alarm interrupt enable prior to programming the time, it is possible that previous time value could be close or match at the time of alarm enable resulting in interrupt trigger which is unexpected (and does not match the time we expect it to trigger). To prevent this scenario from occurring, program the ALM0_EN bit only after the alarm time is appropriately programmed. Of course, I2C programming is non-atomic, so there are loopholes where the interrupt wont trigger if the time requested is in the past at the time of programming the ALM0_EN bit. However, we will not have unexpected interrupts while the time is programmed after the interrupt are enabled. Signed-off-by: Nishanth Menon --- drivers/rtc/rtc-ds1307.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 4ffabb322a9a..59f9ecf323d5 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -742,17 +742,17 @@ static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t) regs[6] &= ~MCP794XX_BIT_ALMX_IF; /* Set alarm match: second, minute, hour, day, date, month. */ regs[6] |= MCP794XX_MSK_ALMX_MATCH; - - if (t->enabled) - regs[0] |= MCP794XX_BIT_ALM0_EN; - else - regs[0] &= ~MCP794XX_BIT_ALM0_EN; + /* Disable interrupt. We will not enable until completely programed */ + regs[0] &= ~MCP794XX_BIT_ALM0_EN; ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs); if (ret < 0) return ret; - return 0; + if (!t->enabled) + return 0; + regs[0] |= MCP7941X_BIT_ALM0_EN; + return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]); } static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled) -- 1.7.9.5 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bear.ext.ti.com ([192.94.94.41]) by gmr-mx.google.com with ESMTPS id t6si6800igz.3.2015.04.20.16.55.30 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 20 Apr 2015 16:55:30 -0700 (PDT) From: Nishanth Menon To: Alexandre Belloni , Alessandro Zummo CC: , , , Subject: [rtc-linux] [PATCH] drivers/rtc/rtc-ds1307.c: Enable the mcp794xx alarm after programming time Date: Mon, 20 Apr 2015 18:55:22 -0500 Message-ID: <1429574122-4284-1-git-send-email-nm@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Reply-To: rtc-linux@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , Alarm interrupt enable register is at offset 0x7, while the time registers for the alarm follow that. When we program Alarm interrupt enable prior to programming the time, it is possible that previous time value could be close or match at the time of alarm enable resulting in interrupt trigger which is unexpected (and does not match the time we expect it to trigger). To prevent this scenario from occurring, program the ALM0_EN bit only after the alarm time is appropriately programmed. Of course, I2C programming is non-atomic, so there are loopholes where the interrupt wont trigger if the time requested is in the past at the time of programming the ALM0_EN bit. However, we will not have unexpected interrupts while the time is programmed after the interrupt are enabled. Signed-off-by: Nishanth Menon --- drivers/rtc/rtc-ds1307.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 4ffabb322a9a..59f9ecf323d5 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -742,17 +742,17 @@ static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t) regs[6] &= ~MCP794XX_BIT_ALMX_IF; /* Set alarm match: second, minute, hour, day, date, month. */ regs[6] |= MCP794XX_MSK_ALMX_MATCH; - - if (t->enabled) - regs[0] |= MCP794XX_BIT_ALM0_EN; - else - regs[0] &= ~MCP794XX_BIT_ALM0_EN; + /* Disable interrupt. We will not enable until completely programed */ + regs[0] &= ~MCP794XX_BIT_ALM0_EN; ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs); if (ret < 0) return ret; - return 0; + if (!t->enabled) + return 0; + regs[0] |= MCP7941X_BIT_ALM0_EN; + return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]); } static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled) -- 1.7.9.5 -- -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/d/optout. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: [PATCH] drivers/rtc/rtc-ds1307.c: Enable the mcp794xx alarm after programming time Date: Mon, 20 Apr 2015 18:55:22 -0500 Message-ID: <1429574122-4284-1-git-send-email-nm@ti.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Alexandre Belloni , Alessandro Zummo Cc: nm@ti.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com List-Id: linux-omap@vger.kernel.org Alarm interrupt enable register is at offset 0x7, while the time registers for the alarm follow that. When we program Alarm interrupt enable prior to programming the time, it is possible that previous time value could be close or match at the time of alarm enable resulting in interrupt trigger which is unexpected (and does not match the time we expect it to trigger). To prevent this scenario from occurring, program the ALM0_EN bit only after the alarm time is appropriately programmed. Of course, I2C programming is non-atomic, so there are loopholes where the interrupt wont trigger if the time requested is in the past at the time of programming the ALM0_EN bit. However, we will not have unexpected interrupts while the time is programmed after the interrupt are enabled. Signed-off-by: Nishanth Menon --- drivers/rtc/rtc-ds1307.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 4ffabb322a9a..59f9ecf323d5 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -742,17 +742,17 @@ static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t) regs[6] &= ~MCP794XX_BIT_ALMX_IF; /* Set alarm match: second, minute, hour, day, date, month. */ regs[6] |= MCP794XX_MSK_ALMX_MATCH; - - if (t->enabled) - regs[0] |= MCP794XX_BIT_ALM0_EN; - else - regs[0] &= ~MCP794XX_BIT_ALM0_EN; + /* Disable interrupt. We will not enable until completely programed */ + regs[0] &= ~MCP794XX_BIT_ALM0_EN; ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs); if (ret < 0) return ret; - return 0; + if (!t->enabled) + return 0; + regs[0] |= MCP7941X_BIT_ALM0_EN; + return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]); } static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled) -- 1.7.9.5