linux-kernel - [PATCH] mfd: mc13xxx-core: Fix PMIC shutdown when reading ADC values

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Message-Id: <1535486560-16267-1-git-send-email-festevam@gmail.com>
Date:   Tue, 28 Aug 2018 17:02:40 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     lee.jones@...aro.org
Cc:     linux-kernel@...r.kernel.org, u.kleine-koenig@...gutronix.de,
        andrey.gusakov@...entembedded.com, cphealy@...il.com,
        Fabio Estevam <fabio.estevam@....com>
Subject: [PATCH] mfd: mc13xxx-core: Fix PMIC shutdown when reading ADC values

From: Fabio Estevam <fabio.estevam@....com>

When trying to read any MC13892 ADC channel on a imx51-babbage board:

# cat /sys/class/hwmon/hwmon0/device/in7_input

The MC13892 PMIC shutdowns completely.

After debugging this issue and comparing the MC13892 and MC13783
initializations done in the vendor kernel, it was noticed that the
CHRGRAWDIV bit of the ADC0 register was not being set.

This bit is set by default after power on, but the driver was
clearing it.

After setting this bit it is possible to read the ADC values correctly.

Signed-off-by: Fabio Estevam <fabio.estevam@....com>
---
 drivers/mfd/mc13xxx-core.c  | 3 ++-
 include/linux/mfd/mc13xxx.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/mc13xxx-core.c b/drivers/mfd/mc13xxx-core.c
index c63e331..f475e84 100644
--- a/drivers/mfd/mc13xxx-core.c
+++ b/drivers/mfd/mc13xxx-core.c
@@ -276,7 +276,8 @@ int mc13xxx_adc_do_conversion(struct mc13xxx *mc13xxx, unsigned int mode,
 
 	mc13xxx_reg_read(mc13xxx, MC13XXX_ADC0, &old_adc0);
 
-	adc0 = MC13XXX_ADC0_ADINC1 | MC13XXX_ADC0_ADINC2;
+	adc0 = MC13XXX_ADC0_ADINC1 | MC13XXX_ADC0_ADINC2 |
+	       MC13XXX_ADC0_CHRGRAWDIV;
 	adc1 = MC13XXX_ADC1_ADEN | MC13XXX_ADC1_ADTRIGIGN | MC13XXX_ADC1_ASC;
 
 	/*
diff --git a/include/linux/mfd/mc13xxx.h b/include/linux/mfd/mc13xxx.h
index 54a3cd8..2ad9bdc 100644
--- a/include/linux/mfd/mc13xxx.h
+++ b/include/linux/mfd/mc13xxx.h
@@ -249,6 +249,7 @@ struct mc13xxx_platform_data {
 #define MC13XXX_ADC0_TSMOD0		(1 << 12)
 #define MC13XXX_ADC0_TSMOD1		(1 << 13)
 #define MC13XXX_ADC0_TSMOD2		(1 << 14)
+#define MC13XXX_ADC0_CHRGRAWDIV		(1 << 15)
 #define MC13XXX_ADC0_ADINC1		(1 << 16)
 #define MC13XXX_ADC0_ADINC2		(1 << 17)
 
-- 
2.7.4