linux-kernel - [PATCH 2/2] rtc: pcf2127: make battery switch-over configurable

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Message-Id: <20241022080121.1594744-3-p.rosenberger@kunbus.com>
Date: Tue, 22 Oct 2024 10:01:21 +0200
From: Philipp Rosenberger <p.rosenberger@...bus.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	linux-rtc@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Lino Sanfilippo <l.sanfilippo@...bus.com>,
	Philipp Rosenberger <p.rosenberger@...bus.com>
Subject: [PATCH 2/2] rtc: pcf2127: make battery switch-over configurable

The battery switch-over function of the PCF2127, PCA2129 and PCF2129
have the opposite default behavior as the PCF2131. If the PCF2131 is
used as replacement for one of the others, the battery switch-over will
be disabled.

Add nxp,battery-switch-over as an optional devicetree property to configure
the battery switch-over, battery low detection and extra power fail
detection functions.

The property reflects the value of the PWRMNG bits of the Control_3
register.

Signed-off-by: Philipp Rosenberger <p.rosenberger@...bus.com>
---
 drivers/rtc/rtc-pcf2127.c | 61 +++++++++++++++++++++++++++++----------
 1 file changed, 46 insertions(+), 15 deletions(-)

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index 9c04c4e1a49c..812764b65b34 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -48,6 +48,7 @@
 #define PCF2127_BIT_CTRL3_BLF                  BIT(2)
 #define PCF2127_BIT_CTRL3_BF                   BIT(3)
 #define PCF2127_BIT_CTRL3_BTSE                 BIT(4)
+#define PCF2127_BIT_CTRL3_PWRMNG_MASK          (BIT(5) | BIT(6) | BIT(7))
 /* Time and date registers */
 #define PCF2127_REG_TIME_BASE          0x03
 #define PCF2127_BIT_SC_OSF                     BIT(7)
@@ -529,6 +530,49 @@ static int pcf2127_watchdog_init(struct device *dev, struct pcf2127 *pcf2127)
        return devm_watchdog_register_device(dev, &pcf2127->wdd);
 }

+static int pcf2127_battery_init(struct device *dev, struct pcf2127 *pcf2127)
+{
+       u8 val = 0xff;
+       int ret;
+
+       /*
+        * Disable battery low/switch-over timestamp and interrupts.
+        * Clear battery interrupt flags which can block new trigger events.
+        * Note: This is the default chip behaviour but added to ensure
+        * correct tamper timestamp and interrupt function.
+        */
+       ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL3,
+                                PCF2127_BIT_CTRL3_BTSE |
+                                PCF2127_BIT_CTRL3_BIE |
+                                PCF2127_BIT_CTRL3_BLIE, 0);
+       if (ret) {
+               dev_err(dev, "%s: interrupt config (ctrl3) failed\n",
+                       __func__);
+               return ret;
+       }
+
+       ret = device_property_read_u8(dev, "nxp,battery-switch-over", &val);
+       if (ret < 0)
+               return 0;
+
+       if (val > 7) {
+               dev_warn(dev,
+                        "%s: ignoring invalid value for nxp,battery-switch-over: %u\n",
+                        __func__, val);
+               return 0;
+       };
+       ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL3,
+                                PCF2127_BIT_CTRL3_PWRMNG_MASK, val << 5);
+       if (ret) {
+               dev_err(dev,
+                       "%s: battery switch-over config (ctrl3) failed\n",
+                       __func__);
+               return ret;
+       }
+
+       return 0;
+}
+
 /* Alarm */
 static int pcf2127_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
@@ -1224,22 +1268,9 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
        }

        pcf2127_watchdog_init(dev, pcf2127);
-
-       /*
-        * Disable battery low/switch-over timestamp and interrupts.
-        * Clear battery interrupt flags which can block new trigger events.
-        * Note: This is the default chip behaviour but added to ensure
-        * correct tamper timestamp and interrupt function.
-        */
-       ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL3,
-                                PCF2127_BIT_CTRL3_BTSE |
-                                PCF2127_BIT_CTRL3_BIE |
-                                PCF2127_BIT_CTRL3_BLIE, 0);
-       if (ret) {
-               dev_err(dev, "%s: interrupt config (ctrl3) failed\n",
-                       __func__);
+       ret = pcf2127_battery_init(dev, pcf2127);
+       if (ret < 0)
                return ret;
-       }

        /*
         * Enable timestamp functions 1 to 4.
--
2.39.5

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