linux-kernel - [PATCH 1/2] rtc: pcf8523: Make DSM for battery switch-over configurable from DT

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Message-Id: <20200719145028.3370-2-miguelborgesdefreitas@gmail.com>
Date:   Sun, 19 Jul 2020 15:50:27 +0100
From:   miguelborgesdefreitas@...il.com
To:     a.zummo@...ertech.it
Cc:     linux@...linux.org.uk, alexandre.belloni@...tlin.com,
        robh+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        miguelborgesdefreitas@...il.com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] rtc: pcf8523: Make DSM for battery switch-over configurable from DT

From: Miguel Borges de Freitas <miguelborgesdefreitas@...il.com>

Signed-off-by: Miguel Borges de Freitas <miguelborgesdefreitas@...il.com>
---
 Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt |  7 ++++++-
 Documentation/devicetree/bindings/rtc/rtc.yaml        |  7 +++++++
 drivers/rtc/rtc-pcf8523.c                             | 13 ++++++++++---
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
index 0b1080c..f715a8f 100644
--- a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
@@ -4,10 +4,14 @@ Required properties:
 - compatible: Should contain "nxp,pcf8523".
 - reg: I2C address for chip.
 
-Optional property:
+Optional properties:
 - quartz-load-femtofarads: The capacitive load of the quartz(x-tal),
   expressed in femto Farad (fF). Valid values are 7000 and 12500.
   Default value (if no value is specified) is 12500fF.
+- pm-enable-dsm: battery switch-over function is enabled in direct
+  switching mode. The power failure condition happens when VDD < VBAT,
+  without requiring VDD to drop below Vth(sw)bat.
+  Default value (if not provided) is the standard mode.
 
 Example:
 
@@ -15,4 +19,5 @@ pcf8523: rtc@68 {
 	compatible = "nxp,pcf8523";
 	reg = <0x68>;
 	quartz-load-femtofarads = <7000>;
+	pm-enable-dsm;
 };
diff --git a/Documentation/devicetree/bindings/rtc/rtc.yaml b/Documentation/devicetree/bindings/rtc/rtc.yaml
index ee237b2..a0048f4 100644
--- a/Documentation/devicetree/bindings/rtc/rtc.yaml
+++ b/Documentation/devicetree/bindings/rtc/rtc.yaml
@@ -47,4 +47,11 @@ properties:
     description:
       Enables wake up of host system on alarm.
 
+  pm-enable-dsm:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Enables the battery switch-over function in direct switching
+      mode. Should be set in systems where VDD is higher than VBAT
+      at all times.
+
 ...
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
index 47e0f41..0c08f91 100644
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -122,7 +122,7 @@ static int pcf8523_load_capacitance(struct i2c_client *client)
 	return err;
 }
 
-static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
+static int pcf8523_set_pm(struct i2c_client *client)
 {
 	u8 value;
 	int err;
@@ -131,7 +131,10 @@ static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
 	if (err < 0)
 		return err;
 
-	value = (value & ~REG_CONTROL3_PM_MASK) | pm;
+	if (of_property_read_bool(client->dev.of_node, "pm-enable-dsm"))
+		value = (value & ~REG_CONTROL3_PM_MASK) | REG_CONTROL3_PM_DSM;
+	else
+		value = (value & ~REG_CONTROL3_PM_MASK) | 0;
 
 	err = pcf8523_write(client, REG_CONTROL3, value);
 	if (err < 0)
@@ -173,6 +176,10 @@ static int pcf8523_start_rtc(struct i2c_client *client)
 	if (err < 0)
 		return err;
 
+	err = pcf8523_set_pm(client);
+	if (err < 0)
+		return err;
+
 	return 0;
 }
 
@@ -352,7 +359,7 @@ static int pcf8523_probe(struct i2c_client *client,
 		dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
 			 err);
 
-	err = pcf8523_set_pm(client, 0);
+	err = pcf8523_set_pm(client);
 	if (err < 0)
 		return err;
 
-- 
1.8.3.1