[PATCH 4/5] rtc: ds1307: Allow configuring DS1337 type chips

[Trent Piepho <tpiepho@kymetacorp.com>]

Move OF configuration code into new function which can be used by both
style of chips.

Extend the DT bindings to allow configuring both input and output
rate, as the DS1337/41 type chips have this ability.

Signed-off-by: Trent Piepho <tpiepho@kymetacorp.com>
---
 .../devicetree/bindings/rtc/dallas,ds1307.rst      |  18 +-
 drivers/rtc/rtc-ds1307.c                           | 188 ++++++++++++---------
 2 files changed, 124 insertions(+), 82 deletions(-)

diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst b/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst
index 52787a8..b9e91f1 100644
--- a/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst
+++ b/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst
@@ -2,22 +2,28 @@ Dallas DS1307 I2C Serial Real-Time Clock
 ========================================
 
 Required properties:
-* ``compatible``: ``dallas,ds1307``, ``dallas,ds1308``, ``dallas,ds1338``
+* ``compatible``: ``dallas,ds1307``, ``dallas,ds1308``, ``dallas,ds1337``,
+		  ``dallas,ds1338``, ``dallas,ds1341``
 	"maxim" can be used in place of "dallas"
 
 * ``reg``: I2C address for chip
 
 Optional properties:
 * ``ext-clock-input``: Enable external clock input pin
-* ``ext-clock-output``:  Enable square wave output.  The above two
-  properties are mutually exclusive
+* ``ext-clock-output``:  Enable square wave output.  On some chips both
+  the above properties can not be enabled at once.
 * ``ext-clock-bb``: Enable external clock on battery power
-* ``ext-clock-rate``:  Expected/Generated rate on external clock pin
-  in Hz.  Allowable values are 1, 50, 60, 4096, 8192, and 32768 Hz. 
+* ``ext-clock-input-rate``:  Expected rate on external clock input pin
+  in Hz.  Allowable values are 1, 50, 60, 4096, 8192, and 32768 Hz.
   Not all values are valid for all configurations.
+* ``ext-clock-output-rate``:  Rate to generate on square wave output pin
+  in Hz.  Allowable values are 1, 50, 60, 4096, 8192, and 32768 Hz.
+  Not all values are valid for all configurations.  Some chips do not allow
+  setting both input and output rate.  In this case, only the correct property
+  should be set.
 
 The default is ext-clock-input, ext-clock-output, and ext-clock-bb
-disabled and ext-clock-rate of 1 Hz.
+disabled and ext-clock-input/output-rate of 1 Hz.
 
 Example::
 	ds1307: rtc@68 {
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 1526273..b772ca3 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -92,6 +92,8 @@ enum ds_type {
 #define DS1337_REG_STATUS	0x0f
 #	define DS1337_BIT_OSF		0x80
 #	define DS1341_BIT_DOSF		0x40
+#	define DS1341_BIT_CLKSEL2	0x10
+#	define DS1341_BIT_CLKSEL1	0x08
 #	define DS1341_BIT_ECLK		0x04
 #	define DS1337_BIT_A2I		0x02
 #	define DS1337_BIT_A1I		0x01
@@ -293,6 +295,70 @@ static const struct rtc_class_ops ds13xx_rtc_ops = {
 	.set_time	= ds1307_set_time,
 };
 
+
+/* Convert rate in Hz to config bits */
+static u8 parse_rate(u32 rate)
+{
+	switch (rate) {
+		default:
+		case 1:     return 0;
+		case 50:    return DS1307_BIT_RS0;
+		case 60:    return DS1307_BIT_RS1;
+		case 4096:  return DS1307_BIT_RS0;
+		case 8192:  return DS1307_BIT_RS1;
+		case 32768: return DS1307_BIT_RS0|DS1307_BIT_RS1;
+	}
+}
+
+/* Produces a config word with DT settings.  This word must be
+ * translated into chip specific bits.  The low 8-bit are basically
+ * identical to the ds1307/1308/1338 control reg to make this
+ * translation simpler.
+ *
+ * Word uses these bits:
+ * DS1308_BIT_ECLK		enable external clock input
+ * DS1307_BIT_SQWE		enable square wave output
+ * DS1308_BIT_BBCLK		enable square wave on battery
+ * DS1307_BIT_RS1/0		square wave output frequency
+ * DS1307_BIT_RS1/0 << 8	external clock input frequency
+ *
+ * The rate select bits will be zero if not specified in the device
+ * tree.
+ */
+static u16 ds1307_config(const struct device_node *np)
+{
+	u16 control = 0;
+	u32 rate;
+
+	if (of_property_read_bool(np, "ext-clock-input"))
+		control |= DS1308_BIT_ECLK;
+
+	if (of_property_read_bool(np, "ext-clock-output"))
+		control |= DS1307_BIT_SQWE;
+
+	if (of_property_read_bool(np, "ext-clock-bb"))
+		control |= DS1308_BIT_BBCLK;
+
+	rate = 0;
+	of_property_read_u32(np, "ext-clock-input-rate", &rate);
+	control |= parse_rate(rate);
+
+	rate = 0;
+	of_property_read_u32(np, "ext-clock-output-rate", &rate);
+	control |= parse_rate(rate) << 8;
+
+	return control;
+}
+
+static void write_if_changed(struct ds1307 *ds1307, u8 *buf,
+				 int reg, u8 value)
+{
+	if (buf[reg] != value) {
+		buf[reg] = value;
+		i2c_smbus_write_byte_data(ds1307->client, reg, buf[reg]);
+	}
+}
+
 static int ds1307_probe(struct device_d *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
@@ -343,82 +409,6 @@ read_rtc:
 		goto exit;
 	}
 
-	if (ds1307->has_alarms) {
-		/*
-		  Make sure no alarm interrupts or square wave signals
-		  are produced by the chip while we are in
-		  bootloader. We do this by configuring the RTC to
-		  generate alarm interrupts (thus disabling square
-		  wave generation), but disabling each individual
-		  alarm interrupt source
-		 */
-		buf[DS1337_REG_CONTROL] |= DS1337_BIT_INTCN;
-		buf[DS1337_REG_CONTROL] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
-
-		i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
-					  buf[DS1337_REG_CONTROL]);
-
-		if (ds1307->type == ds_1341) {
-			/*
-			 * For the above to be true, DS1341 also has to have
-			 * ECLK bit set to 0
-			 */
-			buf[DS1337_REG_STATUS] &= ~DS1341_BIT_ECLK;
-
-			/*
-			 * Let's set additionale RTC bits to
-			 * facilitate maximum power saving.
-			 */
-			buf[DS1337_REG_STATUS] |=  DS1341_BIT_DOSF;
-			buf[DS1337_REG_CONTROL] &= ~DS1341_BIT_EGFIL;
-
-			i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
-						  buf[DS1337_REG_CONTROL]);
-			i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
-						  buf[DS1337_REG_STATUS]);
-		}
-
-	}
-
-	/* Configure clock using OF data if available */
-	if (IS_ENABLED(CONFIG_OFDEVICE) && np && !ds1307->has_alarms) {
-		u8 control = buf[DS1307_REG_CONTROL];
-		u32 rate = 0;
-
-		if (of_property_read_bool(np, "ext-clock-input"))
-			control |= DS1308_BIT_ECLK;
-		else
-			control &= ~DS1308_BIT_ECLK;
-
-		if (of_property_read_bool(np, "ext-clock-output"))
-			control |= DS1307_BIT_SQWE;
-		else
-			control &= ~DS1307_BIT_SQWE;
-
-		if (of_property_read_bool(np, "ext-clock-bb"))
-			control |= DS1308_BIT_BBCLK;
-		else
-			control &= ~DS1308_BIT_BBCLK;
-
-		control &= ~(DS1307_BIT_RS1 | DS1307_BIT_RS0);
-		of_property_read_u32(np, "ext-clock-rate", &rate);
-		switch (rate) {
-			default:
-			case 1:     control |= 0; break;
-			case 50:    control |= 1; break;
-			case 60:    control |= 2; break;
-			case 4096:  control |= 1; break;
-			case 8192:  control |= 2; break;
-			case 32768: control |= 3; break;
-		}
-		dev_dbg(&client->dev, "control reg: 0x%02x\n", control);
-
-		if (buf[DS1307_REG_CONTROL] != control) {
-			i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL, control);
-			buf[DS1307_REG_CONTROL]  = control;
-		}
-	}
-
 	/* Check for clock halted conditions and start clock */
 	fault = 0;
 
@@ -465,6 +455,52 @@ read_rtc:
 		goto read_rtc;
 	}
 
+	/* Configure clock using OF data if available */
+	if (IS_ENABLED(CONFIG_OFDEVICE) && np) {
+		u16 config = ds1307_config(np);
+		if (ds1307->has_alarms) {
+			u8 creg = buf[DS1337_REG_CONTROL];
+			u8 sreg = buf[DS1337_REG_STATUS];
+
+			/* Translate bits to the DS1337_REG_CONTROL format */
+			creg &= ~(DS1337_BIT_RS2 | DS1337_BIT_RS1);
+			creg |= (config & 0x003) << 3;
+			sreg &= ~(DS1341_BIT_CLKSEL2 | DS1341_BIT_CLKSEL1);
+			sreg |= (config & 0x300) >> 5;
+			creg &= ~(DS1337_BIT_INTCN | DS1341_BIT_ECLK);
+			creg |= config & DS1307_BIT_SQWE ? 0 : DS1337_BIT_INTCN;
+			creg |= config & DS1308_BIT_ECLK ? DS1341_BIT_ECLK : 0;
+
+			/* Make sure no alarm interrupts are triggered by
+			 * disabling alarms.  Square wave signals are already
+			 * disabled unless the DT turned them on above.  */
+			creg &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
+
+			/*
+			 * Let's set additional RTC bits to
+			 * facilitate maximum power saving.
+			 */
+			if (ds1307->type == ds_1341) {
+				buf[DS1337_REG_STATUS] |=  DS1341_BIT_DOSF;
+				buf[DS1337_REG_CONTROL] &= ~DS1341_BIT_EGFIL;
+			}
+
+			write_if_changed(ds1307, buf, DS1337_REG_CONTROL, creg);
+			write_if_changed(ds1307, buf, DS1337_REG_STATUS, sreg);
+		} else {
+			u8 reg = buf[DS1307_REG_CONTROL];
+
+			/* Combine input and output rate bits */
+			config |= (config >> 8);
+			reg &= ~(DS1308_BIT_ECLK | DS1307_BIT_SQWE |
+			         DS1308_BIT_BBCLK |
+				 DS1307_BIT_RS1 | DS1307_BIT_RS0);
+			reg |= config;
+
+			write_if_changed(ds1307, buf, DS1307_REG_CONTROL, reg);
+		}
+	}
+
 	if (buf[DS1307_REG_HOUR] & DS1307_BIT_12HR) {
 		/*
 		 * Be sure we're in 24 hour mode.  Multi-master systems
-- 
2.7.0.25.gfc10eb5.dirty


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