linux-kernel - [PATCH 1/4] rtc: mcp795: fix invalid month setting.

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Date:   Mon,  5 Dec 2016 14:11:50 +0100
From:   Emil Bartczak <emilbart@...il.com>
To:     a.zummo@...ertech.it
Cc:     alexandre.belloni@...e-electrons.com, rtc-linux@...glegroups.com,
        linux-kernel@...r.kernel.org, Emil Bartczak <emilbart@...il.com>
Subject: [PATCH 1/4] rtc: mcp795: fix invalid month setting.

The 10 month register was always set to value 0 in the RTC hardware.
Due to the bug month November or December became February.
---
 drivers/rtc/rtc-mcp795.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-mcp795.c b/drivers/rtc/rtc-mcp795.c
index 4021fd0..266328b 100644
--- a/drivers/rtc/rtc-mcp795.c
+++ b/drivers/rtc/rtc-mcp795.c
@@ -29,7 +29,7 @@
 #define MCP795_EEWREN	0x06
 #define MCP795_SRREAD	0x05
 #define MCP795_SRWRITE	0x01
-#define MCP795_READ		0x13
+#define MCP795_READ	0x13
 #define MCP795_WRITE	0x12
 #define MCP795_UNLOCK	0x14
 #define MCP795_IDWRITE	0x32
@@ -39,6 +39,7 @@
 
 #define MCP795_ST_BIT	0x80
 #define MCP795_24_BIT	0x40
+#define MCP795_LP_BIT	0x20
 
 static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
 {
@@ -108,7 +109,8 @@ static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
 	data[1] = (data[1] & 0x80) | ((tim->tm_min / 10) << 4) | (tim->tm_min % 10);
 	data[2] = ((tim->tm_hour / 10) << 4) | (tim->tm_hour % 10);
 	data[4] = ((tim->tm_mday / 10) << 4) | ((tim->tm_mday) % 10);
-	data[5] = (data[5] & 0x10) | (tim->tm_mon / 10) | (tim->tm_mon % 10);
+	data[5] = (data[5] & MCP795_LP_BIT) |
+			((tim->tm_mon / 10) << 4) | (tim->tm_mon % 10);
 
 	if (tim->tm_year > 100)
 		tim->tm_year -= 100;
@@ -137,11 +139,11 @@ static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
 	if (ret)
 		return ret;
 
-	tim->tm_sec		= ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
-	tim->tm_min		= ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
+	tim->tm_sec	= ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
+	tim->tm_min	= ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
 	tim->tm_hour	= ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
 	tim->tm_mday	= ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
-	tim->tm_mon		= ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
+	tim->tm_mon	= ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
 	tim->tm_year	= ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 100; /* Assume we are in 20xx */
 
 	dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
-- 
2.7.4