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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Chu Lin <linchuyuan@google.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 19/36] hwmon: (max6697) Make sure the OVERT mask is set correctly
Date:   Tue,  7 Jul 2020 17:17:11 +0200
Message-Id: <20200707145750.053560653@linuxfoundation.org>
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From: Chu Lin <linchuyuan@google.com>

[ Upstream commit 016983d138cbe99a5c0aaae0103ee88f5300beb3 ]

Per the datasheet for max6697, OVERT mask and ALERT mask are different.
For example, the 7th bit of OVERT is the local channel but for alert
mask, the 6th bit is the local channel. Therefore, we can't apply the
same mask for both registers. In addition to that, the max6697 driver
is supposed to be compatibale with different models. I manually went over
all the listed chips and made sure all chip types have the same layout.

Testing;
    mask value of 0x9 should map to 0x44 for ALERT and 0x84 for OVERT.
    I used iotool to read the reg value back to verify. I only tested this
    change on max6581.

Reference:
https://datasheets.maximintegrated.com/en/ds/MAX6581.pdf
https://datasheets.maximintegrated.com/en/ds/MAX6697.pdf
https://datasheets.maximintegrated.com/en/ds/MAX6699.pdf

Signed-off-by: Chu Lin <linchuyuan@google.com>
Fixes: 5372d2d71c46e ("hwmon: Driver for Maxim MAX6697 and compatibles")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/max6697.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/max6697.c b/drivers/hwmon/max6697.c
index 221fd14920576..6df28fe0577da 100644
--- a/drivers/hwmon/max6697.c
+++ b/drivers/hwmon/max6697.c
@@ -47,8 +47,9 @@ static const u8 MAX6697_REG_CRIT[] = {
  * Map device tree / platform data register bit map to chip bit map.
  * Applies to alert register and over-temperature register.
  */
-#define MAX6697_MAP_BITS(reg)	((((reg) & 0x7e) >> 1) | \
+#define MAX6697_ALERT_MAP_BITS(reg)	((((reg) & 0x7e) >> 1) | \
 				 (((reg) & 0x01) << 6) | ((reg) & 0x80))
+#define MAX6697_OVERT_MAP_BITS(reg) (((reg) >> 1) | (((reg) & 0x01) << 7))
 
 #define MAX6697_REG_STAT(n)		(0x44 + (n))
 
@@ -587,12 +588,12 @@ static int max6697_init_chip(struct max6697_data *data,
 		return ret;
 
 	ret = i2c_smbus_write_byte_data(client, MAX6697_REG_ALERT_MASK,
-					MAX6697_MAP_BITS(pdata->alert_mask));
+				MAX6697_ALERT_MAP_BITS(pdata->alert_mask));
 	if (ret < 0)
 		return ret;
 
 	ret = i2c_smbus_write_byte_data(client, MAX6697_REG_OVERT_MASK,
-				MAX6697_MAP_BITS(pdata->over_temperature_mask));
+			MAX6697_OVERT_MAP_BITS(pdata->over_temperature_mask));
 	if (ret < 0)
 		return ret;
 
-- 
2.25.1