iio: accel: Add trigger support for STK8BA50

Add data-ready interrupts and trigger support for STK8BA50.

Additional changes:
- read_accel now returns raw acceleration data instead of the
  sign_extend32 value
- read_raw will now enable/disable the sensor with each reading

Change-Id: I9c2d7be4256b2dcc5546e4432308ea54f8004333
Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/stk8ba50.c

@@ -11,11 +11,17 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
+#include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
 
 #define STK8BA50_REG_XOUT			0x02
 #define STK8BA50_REG_YOUT			0x04
@@ -24,6 +30,8 @@
 #define STK8BA50_REG_BWSEL			0x10
 #define STK8BA50_REG_POWMODE			0x11
 #define STK8BA50_REG_SWRST			0x14
+#define STK8BA50_REG_INTEN2			0x17
+#define STK8BA50_REG_INTMAP2			0x1A
 
 #define STK8BA50_MODE_NORMAL			0
 #define STK8BA50_MODE_SUSPEND			1
@@ -31,8 +39,14 @@
 #define STK8BA50_DATA_SHIFT			6
 #define STK8BA50_RESET_CMD			0xB6
 #define STK8BA50_SR_1792HZ_IDX			7
+#define STK8BA50_DREADY_INT_MASK		0x10
+#define STK8BA50_DREADY_INT_MAP			0x81
+#define STK8BA50_ALL_CHANNEL_MASK		7
+#define STK8BA50_ALL_CHANNEL_SIZE		6
 
 #define STK8BA50_DRIVER_NAME			"stk8ba50"
+#define STK8BA50_GPIO				"stk8ba50_gpio"
+#define STK8BA50_IRQ_NAME			"stk8ba50_event"
 
 #define STK8BA50_SCALE_AVAIL			"0.0384 0.0767 0.1534 0.3069"
 
@@ -68,14 +82,29 @@ static const struct {
 	{0x0C, 224}, {0x0D, 448}, {0x0E, 896}, {0x0F, 1792}
 };
 
+/* Used to map scan mask bits to their corresponding channel register. */
+static const int stk8ba50_channel_table[] = {
+	STK8BA50_REG_XOUT,
+	STK8BA50_REG_YOUT,
+	STK8BA50_REG_ZOUT
+};
+
 struct stk8ba50_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	int range;
 	u8 sample_rate_idx;
+	struct iio_trigger *dready_trig;
+	bool dready_trigger_on;
+	/*
+	 * 3 x 16-bit channels (10-bit data, 6-bit padding) +
+	 * 1 x 16 padding +
+	 * 4 x 16 64-bit timestamp
+	 */
+	s16 buffer[8];
 };
 
-#define STK8BA50_ACCEL_CHANNEL(reg, axis) {				\
+#define STK8BA50_ACCEL_CHANNEL(index, reg, axis) {			\
 	.type = IIO_ACCEL,						\
 	.address = reg,							\
 	.modified = 1,							\
@@ -83,12 +112,21 @@ struct stk8ba50_data {
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
 				    BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = index,						\
+	.scan_type = {							\
+		.sign = 's',						\
+		.realbits = 10,						\
+		.storagebits = 16,					\
+		.shift = STK8BA50_DATA_SHIFT,				\
+		.endianness = IIO_CPU,					\
+	},								\
 }
 
 static const struct iio_chan_spec stk8ba50_channels[] = {
-	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_XOUT, X),
-	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_YOUT, Y),
-	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_ZOUT, Z),
+	STK8BA50_ACCEL_CHANNEL(0, STK8BA50_REG_XOUT, X),
+	STK8BA50_ACCEL_CHANNEL(1, STK8BA50_REG_YOUT, Y),
+	STK8BA50_ACCEL_CHANNEL(2, STK8BA50_REG_ZOUT, Z),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
 };
 
 static IIO_CONST_ATTR(in_accel_scale_available, STK8BA50_SCALE_AVAIL);
@@ -116,7 +154,61 @@ static int stk8ba50_read_accel(struct stk8ba50_data *data, u8 reg)
 		return ret;
 	}
 
-	return sign_extend32(ret >> STK8BA50_DATA_SHIFT, 9);
+	return ret;
+}
+
+static int stk8ba50_data_rdy_trigger_set_state(struct iio_trigger *trig,
+					       bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct stk8ba50_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (state)
+		ret = i2c_smbus_write_byte_data(data->client,
+			STK8BA50_REG_INTEN2, STK8BA50_DREADY_INT_MASK);
+	else
+		ret = i2c_smbus_write_byte_data(data->client,
+			STK8BA50_REG_INTEN2, 0x00);
+
+	if (ret < 0)
+		dev_err(&data->client->dev, "failed to set trigger state\n");
+	else
+		data->dready_trigger_on = state;
+
+	return ret;
+}
+
+static const struct iio_trigger_ops stk8ba50_trigger_ops = {
+	.set_trigger_state = stk8ba50_data_rdy_trigger_set_state,
+	.owner = THIS_MODULE,
+};
+
+static int stk8ba50_set_power(struct stk8ba50_data *data, bool mode)
+{
+	int ret;
+	u8 masked_reg;
+	struct i2c_client *client = data->client;
+
+	ret = i2c_smbus_read_byte_data(client, STK8BA50_REG_POWMODE);
+	if (ret < 0)
+		goto exit_err;
+
+	if (mode)
+		masked_reg = ret | STK8BA50_MODE_POWERBIT;
+	else
+		masked_reg = ret & (~STK8BA50_MODE_POWERBIT);
+
+	ret = i2c_smbus_write_byte_data(client, STK8BA50_REG_POWMODE,
+					masked_reg);
+	if (ret < 0)
+		goto exit_err;
+
+	return ret;
+
+exit_err:
+	dev_err(&client->dev, "failed to change sensor mode\n");
+	return ret;
 }
 
 static int stk8ba50_read_raw(struct iio_dev *indio_dev,
@@ -124,11 +216,26 @@ static int stk8ba50_read_raw(struct iio_dev *indio_dev,
 			     int *val, int *val2, long mask)
 {
 	struct stk8ba50_data *data = iio_priv(indio_dev);
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
 		mutex_lock(&data->lock);
-		*val = stk8ba50_read_accel(data, chan->address);
+		ret = stk8ba50_set_power(data, STK8BA50_MODE_NORMAL);
+		if (ret < 0) {
+			mutex_unlock(&data->lock);
+			return -EINVAL;
+		}
+		ret = stk8ba50_read_accel(data, chan->address);
+		if (ret < 0) {
+			stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);
+			mutex_unlock(&data->lock);
+			return -EINVAL;
+		}
+		*val = sign_extend32(ret >> STK8BA50_DATA_SHIFT, 9);
+		stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);
 		mutex_unlock(&data->lock);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
@@ -208,30 +315,100 @@ static const struct iio_info stk8ba50_info = {
 	.attrs			= &stk8ba50_attribute_group,
 };
 
-static int stk8ba50_set_power(struct stk8ba50_data *data, bool mode)
+static irqreturn_t stk8ba50_trigger_handler(int irq, void *p)
 {
-	int ret;
-	u8 masked_reg;
-	struct i2c_client *client = data->client;
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct stk8ba50_data *data = iio_priv(indio_dev);
+	int bit, ret, i = 0;
 
-	ret = i2c_smbus_read_byte_data(client, STK8BA50_REG_POWMODE);
+	mutex_lock(&data->lock);
+	/*
+	 * Do a bulk read if all channels are requested,
+	 * from 0x02 (XOUT1) to 0x07 (ZOUT2)
+	 */
+	if (*(indio_dev->active_scan_mask) == STK8BA50_ALL_CHANNEL_MASK) {
+		ret = i2c_smbus_read_i2c_block_data(data->client,
+						    STK8BA50_REG_XOUT,
+						    STK8BA50_ALL_CHANNEL_SIZE,
+						    (u8 *)data->buffer);
+		if (ret < STK8BA50_ALL_CHANNEL_SIZE) {
+			dev_err(&data->client->dev, "register read failed\n");
+			goto err;
+		}
+	} else {
+		for_each_set_bit(bit, indio_dev->active_scan_mask,
+				 indio_dev->masklength) {
+			ret = stk8ba50_read_accel(data,
+						  stk8ba50_channel_table[bit]);
 			if (ret < 0)
-		goto exit_err;
+				goto err;
 
-	if (mode)
-		masked_reg = ret | STK8BA50_MODE_POWERBIT;
-	else
-		masked_reg = ret & (~STK8BA50_MODE_POWERBIT);
+			data->buffer[i++] = ret;
+		}
+	}
+	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+					   pf->timestamp);
+err:
+	mutex_unlock(&data->lock);
+	iio_trigger_notify_done(indio_dev->trig);
 
-	ret = i2c_smbus_write_byte_data(client, STK8BA50_REG_POWMODE,
-					masked_reg);
-	if (ret < 0)
-		goto exit_err;
+	return IRQ_HANDLED;
+}
 
-	return ret;
+static irqreturn_t stk8ba50_data_rdy_trig_poll(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct stk8ba50_data *data = iio_priv(indio_dev);
+
+	if (data->dready_trigger_on)
+		iio_trigger_poll(data->dready_trig);
+
+	return IRQ_HANDLED;
+}
+
+static int stk8ba50_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct stk8ba50_data *data = iio_priv(indio_dev);
+
+	return stk8ba50_set_power(data, STK8BA50_MODE_NORMAL);
+}
+
+static int stk8ba50_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	struct stk8ba50_data *data = iio_priv(indio_dev);
+
+	return stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);
+}
+
+static const struct iio_buffer_setup_ops stk8ba50_buffer_setup_ops = {
+	.preenable   = stk8ba50_buffer_preenable,
+	.postenable  = iio_triggered_buffer_postenable,
+	.predisable  = iio_triggered_buffer_predisable,
+	.postdisable = stk8ba50_buffer_postdisable,
+};
+
+static int stk8ba50_gpio_probe(struct i2c_client *client)
+{
+	struct device *dev;
+	struct gpio_desc *gpio;
+	int ret;
+
+	if (!client)
+		return -EINVAL;
+
+	dev = &client->dev;
+
+	/* data ready gpio interrupt pin */
+	gpio = devm_gpiod_get_index(dev, STK8BA50_GPIO, 0, GPIOD_IN);
+	if (IS_ERR(gpio)) {
+		dev_err(dev, "acpi gpio get index failed\n");
+		return PTR_ERR(gpio);
+	}
+
+	ret = gpiod_to_irq(gpio);
+	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
 
-exit_err:
-	dev_err(&client->dev, "failed to change sensor mode\n");
 	return ret;
 }
 
@@ -274,14 +451,78 @@ static int stk8ba50_probe(struct i2c_client *client,
 	/* The default sampling rate is 1792 Hz (maximum) */
 	data->sample_rate_idx = STK8BA50_SR_1792HZ_IDX;
 
+	/* Set up interrupts */
+	ret = i2c_smbus_write_byte_data(client,
+			STK8BA50_REG_INTEN2, STK8BA50_DREADY_INT_MASK);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to set up interrupts\n");
+		goto err_power_off;
+	}
+	ret = i2c_smbus_write_byte_data(client,
+			STK8BA50_REG_INTMAP2, STK8BA50_DREADY_INT_MAP);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to set up interrupts\n");
+		goto err_power_off;
+	}
+
+	if (client->irq < 0)
+		client->irq = stk8ba50_gpio_probe(client);
+
+	if (client->irq >= 0) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+						stk8ba50_data_rdy_trig_poll,
+						NULL,
+						IRQF_TRIGGER_RISING |
+						IRQF_ONESHOT,
+						STK8BA50_IRQ_NAME,
+						indio_dev);
+		if (ret < 0) {
+			dev_err(&client->dev, "request irq %d failed\n",
+				client->irq);
+			goto err_power_off;
+		}
+
+		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
+							   "%s-dev%d",
+							   indio_dev->name,
+							   indio_dev->id);
+		if (!data->dready_trig) {
+			ret = -ENOMEM;
+			goto err_power_off;
+		}
+
+		data->dready_trig->dev.parent = &client->dev;
+		data->dready_trig->ops = &stk8ba50_trigger_ops;
+		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
+		ret = iio_trigger_register(data->dready_trig);
+		if (ret) {
+			dev_err(&client->dev, "iio trigger register failed\n");
+			goto err_power_off;
+		}
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev,
+					 iio_pollfunc_store_time,
+					 stk8ba50_trigger_handler,
+					 &stk8ba50_buffer_setup_ops);
+	if (ret < 0) {
+		dev_err(&client->dev, "iio triggered buffer setup failed\n");
+		goto err_trigger_unregister;
+	}
+
 	ret = iio_device_register(indio_dev);
 	if (ret < 0) {
 		dev_err(&client->dev, "device_register failed\n");
-		goto err_power_off;
+		goto err_buffer_cleanup;
 	}
 
 	return ret;
 
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+err_trigger_unregister:
+	if (data->dready_trig)
+		iio_trigger_unregister(data->dready_trig);
 err_power_off:
 	stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);
 	return ret;
@@ -290,10 +531,15 @@ static int stk8ba50_probe(struct i2c_client *client,
 static int stk8ba50_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct stk8ba50_data *data = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
 
-	return stk8ba50_set_power(iio_priv(indio_dev), STK8BA50_MODE_SUSPEND);
+	if (data->dready_trig)
+		iio_trigger_unregister(data->dready_trig);
+
+	return stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);
 }
 
 #ifdef CONFIG_PM_SLEEP