[PATCH v2 1/3] iio: adc: ti-ads112c14: add DRDY interrupt support

Add handling for the DRDY interrupt to wait for data ready events rather
than polling (only when it is wired up).

Signed-off-by: David Lechner (TI) <[email protected]>
---

Small note: the hard-coded 100 ms timeout will be replaced in a future
series with a dynamic value, so I didn't bother with a macro or comments
to explain why the value was chosen.

And passing indio_dev instead of data to irq is intentional as it will
be used in the next patch.
---
 drivers/iio/adc/ti-ads112c14.c | 105 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 95 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
index 8ad8caee0ff7..177f7064092e 100644
--- a/drivers/iio/adc/ti-ads112c14.c
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -10,6 +10,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/cleanup.h>
+#include <linux/completion.h>
 #include <linux/crc8.h>
 #include <linux/delay.h>
 #include <linux/dev_printk.h>
@@ -19,6 +20,7 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
+#include <linux/interrupt.h>
 #include <linux/math64.h>
 #include <linux/minmax.h>
 #include <linux/module.h>
@@ -117,9 +119,15 @@
 #define   ADS112C14_GPIO_CFG_GPIO2_CFG			GENMASK(5, 4)
 #define   ADS112C14_GPIO_CFG_GPIO1_CFG			GENMASK(3, 2)
 #define   ADS112C14_GPIO_CFG_GPIO0_CFG			GENMASK(1, 0)
+#define     ADS112C14_GPIO_CFG_GPIO_CFG_DISABLED	  0
+#define     ADS112C14_GPIO_CFG_GPIO_CFG_INPUT		  1
+#define     ADS112C14_GPIO_CFG_GPIO_CFG_OUTPUT_PUSH_PULL  2
+#define     ADS112C14_GPIO_CFG_GPIO_CFG_OUTPUT_OPEN_DRAIN 3
 
 #define ADS112C14_REG_GPIO_DATA_OUTPUT			0x0C
 #define   ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC		BIT(7)
+#define     ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC_DAT_OUT  0
+#define     ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC_DRDY	  1
 #define   ADS112C14_GPIO_DATA_OUTPUT_GPIO2_SRC		BIT(6)
 #define   ADS112C14_GPIO_DATA_OUTPUT_GPIO3_DAT_OUT	BIT(3)
 #define   ADS112C14_GPIO_DATA_OUTPUT_GPIO2_DAT_OUT	BIT(2)
@@ -251,6 +259,8 @@ struct ads112c14_data {
 	struct regmap *regmap;
 	/* Synchronizes access to register value fields. */
 	struct mutex lock;
+	int drdy_irq;
+	struct completion drdy_completion;
 	bool i2c_crc_enabled;
 	u32 avdd_uV;
 	u32 ext_ref_uV;
@@ -265,6 +275,16 @@ struct ads112c14_data {
 						 ARRAY_SIZE(ads112c14_sys_mon_channels));
 };
 
+static irqreturn_t ads112c14_drdy_irq_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct ads112c14_data *data = iio_priv(indio_dev);
+
+	complete(&data->drdy_completion);
+
+	return IRQ_HANDLED;
+}
+
 static bool ads112c14_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
@@ -581,12 +601,50 @@ static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
 	return 0;
 }
 
+static int ads112c14_wait_for_conversion_irq(struct ads112c14_data *data)
+{
+	unsigned long remaining;
+	int ret;
+
+	reinit_completion(&data->drdy_completion);
+	enable_irq(data->drdy_irq);
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL,
+			   ADS112C14_CONVERSION_CTRL_START);
+	if (ret)
+		goto out;
+
+	remaining = wait_for_completion_timeout(&data->drdy_completion,
+						msecs_to_jiffies(100));
+	ret = remaining ? 0 : -ETIMEDOUT;
+
+out:
+	disable_irq(data->drdy_irq);
+
+	return ret;
+}
+
+static int ads112c14_wait_for_conversion_poll(struct ads112c14_data *data)
+{
+	u32 reg_val;
+	int ret;
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL,
+			   ADS112C14_CONVERSION_CTRL_START);
+	if (ret)
+		return ret;
+
+	return regmap_read_poll_timeout(data->regmap,
+					ADS112C14_REG_STATUS_MSB, reg_val,
+					FIELD_GET(ADS112C14_STATUS_MSB_DRDY, reg_val),
+					1 * USEC_PER_MSEC, 100 * USEC_PER_MSEC);
+}
+
 static int ads112c14_single_conversion(struct ads112c14_data *data,
 				       const struct iio_chan_spec *chan,
 				       u8 *buf, bool for_scan)
 {
 	struct i2c_client *client = to_i2c_client(regmap_get_device(data->regmap));
-	u32 reg_val;
 	int ret;
 
 	guard(mutex)(&data->lock);
@@ -601,15 +659,10 @@ static int ads112c14_single_conversion(struct ads112c14_data *data,
 			return ret;
 	}
 
-	ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL,
-			   ADS112C14_CONVERSION_CTRL_START);
-	if (ret)
-		return ret;
-
-	ret = regmap_read_poll_timeout(data->regmap,
-				       ADS112C14_REG_STATUS_MSB, reg_val,
-				       FIELD_GET(ADS112C14_STATUS_MSB_DRDY, reg_val),
-				       1 * USEC_PER_MSEC, 100 * USEC_PER_MSEC);
+	if (data->drdy_irq)
+		ret = ads112c14_wait_for_conversion_irq(data);
+	else
+		ret = ads112c14_wait_for_conversion_poll(data);
 	if (ret)
 		return ret;
 
@@ -1392,6 +1445,38 @@ static int ads112c14_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	if (device_property_present(dev, "interrupts")) {
+		data->drdy_irq = fwnode_irq_get_byname(dev_fwnode(dev), "drdy");
+		if (data->drdy_irq < 0)
+			return dev_err_probe(dev, data->drdy_irq,
+					     "failed to get drdy interrupt\n");
+
+		/*
+		 * REVISIT: would probably need to implement a pin controller in
+		 * order to support open drain option here.
+		 */
+		ret = regmap_update_bits(data->regmap, ADS112C14_REG_GPIO_CFG,
+					 ADS112C14_GPIO_CFG_GPIO3_CFG,
+					 FIELD_PREP(ADS112C14_GPIO_CFG_GPIO3_CFG,
+						    ADS112C14_GPIO_CFG_GPIO_CFG_OUTPUT_PUSH_PULL));
+		if (ret)
+			return ret;
+
+		ret = regmap_update_bits(data->regmap, ADS112C14_REG_GPIO_DATA_OUTPUT,
+					 ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC,
+					 FIELD_PREP(ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC,
+						    ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC_DRDY));
+		if (ret)
+			return ret;
+
+		init_completion(&data->drdy_completion);
+
+		ret = devm_request_irq(dev, data->drdy_irq, ads112c14_drdy_irq_handler,
+				       IRQF_NO_AUTOEN, dev_name(dev), indio_dev);
+		if (ret)
+			return ret;
+	}
+
 	ads112c14_populate_tables(data);
 
 	indio_dev->name = info->name;

-- 
2.43.0