linux-kernel - [PATCH] rtc: rs5c372: fix incorrect oscillation value on r2221tl

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Date:   Mon, 6 Dec 2021 13:58:31 +0100
From:   Camel Guo <camel.guo@...s.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     <kernel@...s.com>, Camel Guo <camelg@...s.com>,
        <linux-rtc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] rtc: rs5c372: fix incorrect oscillation value on r2221tl

From: Camel Guo <camelg@...s.com>

The XSL bit only exists in RS5C372A/B. On other Ricoh RTC chips
supported in rs5c372, this bit has different meaning. For example, on
R2221x and R2223x, this bit of oscillation adjustment register
determines the operation frequency of oscillation adjustment circuit and
the oscillation is always 32768HZ. But rs5c372_get_trim gives 32000HZ to
osc when DEV is 1.

Signed-off-by: Camel Guo <camelg@...s.com>
---
 drivers/rtc/rtc-rs5c372.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 80980414890c..f031f83fa1a2 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -28,7 +28,7 @@
 #define RS5C372_REG_MONTH	5
 #define RS5C372_REG_YEAR	6
 #define RS5C372_REG_TRIM	7
-#	define RS5C372_TRIM_XSL		0x80
+#	define RS5C372_TRIM_XSL		0x80		/* only if RS5C372[a|b] */
 #	define RS5C372_TRIM_MASK	0x7F
 
 #define RS5C_REG_ALARM_A_MIN	8			/* or ALARM_W */
@@ -324,8 +324,12 @@ static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
 	struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
 	u8 tmp = rs5c372->regs[RS5C372_REG_TRIM];
 
-	if (osc)
-		*osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
+	if (osc) {
+		if (rs5c372->type == rtc_rs5c372a || rs5c372->type == rtc_rs5c372b)
+			*osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
+		else
+			*osc = 32768;
+	}
 
 	if (trim) {
 		dev_dbg(&client->dev, "%s: raw trim=%x\n", __func__, tmp);
-- 
2.20.1