iio: imu: st_lsm6dsx: add hw FIFO support to i2c controller

Introduce hw FIFO support to lsm6dsx i2c controller.
st_lsm6dsx sensor-hub relies on SLV0 for slave configuration since SLV0
is the only channel that can be used to write into i2c slave devices.
SLV{1,2,3} channels are used to read external data and push them into
the hw FIFO
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h

@@ -130,18 +130,22 @@ struct st_lsm6dsx_hw_ts_settings {
  * @master_en: master config register info (addr + mask).
  * @pullup_en: i2c controller pull-up register info (addr + mask).
  * @aux_sens: aux sensor register info (addr + mask).
+ * @wr_once: write_once register info (addr + mask).
  * @shub_out: sensor hub first output register info.
  * @slv0_addr: slave0 address in secondary page.
  * @dw_slv0_addr: slave0 write register address in secondary page.
+ * @batch_en: Enable/disable FIFO batching.
  */
 struct st_lsm6dsx_shub_settings {
 	struct st_lsm6dsx_reg page_mux;
 	struct st_lsm6dsx_reg master_en;
 	struct st_lsm6dsx_reg pullup_en;
 	struct st_lsm6dsx_reg aux_sens;
+	struct st_lsm6dsx_reg wr_once;
 	u8 shub_out;
 	u8 slv0_addr;
 	u8 dw_slv0_addr;
+	u8 batch_en;
 };
 
 enum st_lsm6dsx_ext_sensor_id {

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c

@@ -68,6 +68,9 @@ enum st_lsm6dsx_fifo_tag {
 	ST_LSM6DSX_GYRO_TAG = 0x01,
 	ST_LSM6DSX_ACC_TAG = 0x02,
 	ST_LSM6DSX_TS_TAG = 0x04,
+	ST_LSM6DSX_EXT0_TAG = 0x0f,
+	ST_LSM6DSX_EXT1_TAG = 0x10,
+	ST_LSM6DSX_EXT2_TAG = 0x11,
 };
 
 static const
@@ -460,6 +463,12 @@ st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
 	struct st_lsm6dsx_sensor *sensor;
 	struct iio_dev *iio_dev;
 
+	/*
+	 * EXT_TAG are managed in FIFO fashion so ST_LSM6DSX_EXT0_TAG
+	 * corresponds to the first enabled channel, ST_LSM6DSX_EXT1_TAG
+	 * to the second one and ST_LSM6DSX_EXT2_TAG to the last enabled
+	 * channel
+	 */
 	switch (tag) {
 	case ST_LSM6DSX_GYRO_TAG:
 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_GYRO];
@@ -467,6 +476,24 @@ st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
 	case ST_LSM6DSX_ACC_TAG:
 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_ACC];
 		break;
+	case ST_LSM6DSX_EXT0_TAG:
+		if (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT0))
+			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT0];
+		else if (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT1))
+			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT1];
+		else
+			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
+		break;
+	case ST_LSM6DSX_EXT1_TAG:
+		if ((hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT0)) &&
+		    (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT1)))
+			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT1];
+		else
+			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
+		break;
+	case ST_LSM6DSX_EXT2_TAG:
+		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -593,13 +620,21 @@ static int st_lsm6dsx_update_fifo(struct iio_dev *iio_dev, bool enable)
 			goto out;
 	}
 
-	err = st_lsm6dsx_sensor_set_enable(sensor, enable);
-	if (err < 0)
-		goto out;
+	if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
+	    sensor->id == ST_LSM6DSX_ID_EXT1 ||
+	    sensor->id == ST_LSM6DSX_ID_EXT2) {
+		err = st_lsm6dsx_shub_set_enable(sensor, enable);
+		if (err < 0)
+			goto out;
+	} else {
+		err = st_lsm6dsx_sensor_set_enable(sensor, enable);
+		if (err < 0)
+			goto out;
 
-	err = st_lsm6dsx_set_fifo_odr(sensor, enable);
-	if (err < 0)
-		goto out;
+		err = st_lsm6dsx_set_fifo_odr(sensor, enable);
+		if (err < 0)
+			goto out;
+	}
 
 	err = st_lsm6dsx_update_decimators(hw);
 	if (err < 0)

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

@@ -337,9 +337,14 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = {
 				.addr = 0x14,
 				.mask = GENMASK(1, 0),
 			},
+			.wr_once = {
+				.addr = 0x14,
+				.mask = BIT(6),
+			},
 			.shub_out = 0x02,
 			.slv0_addr = 0x15,
 			.dw_slv0_addr = 0x21,
+			.batch_en = BIT(3),
 		}
 	},
 };

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c

@@ -148,6 +148,26 @@ static int st_lsm6dsx_shub_write_reg(struct st_lsm6dsx_hw *hw, u8 addr,
 	return err;
 }
 
+static int
+st_lsm6dsx_shub_write_reg_with_mask(struct st_lsm6dsx_hw *hw, u8 addr,
+				    u8 mask, u8 val)
+{
+	int err;
+
+	mutex_lock(&hw->page_lock);
+	err = st_lsm6dsx_set_page(hw, true);
+	if (err < 0)
+		goto out;
+
+	err = regmap_update_bits(hw->regmap, addr, mask, val);
+
+	st_lsm6dsx_set_page(hw, false);
+out:
+	mutex_unlock(&hw->page_lock);
+
+	return err;
+}
+
 static int st_lsm6dsx_shub_master_enable(struct st_lsm6dsx_sensor *sensor,
 					 bool enable)
 {
@@ -238,6 +258,18 @@ st_lsm6dsx_shub_write(struct st_lsm6dsx_sensor *sensor, u8 addr,
 	int err, i;
 
 	hub_settings = &hw->settings->shub_settings;
+	if (hub_settings->wr_once.addr) {
+		unsigned int data;
+
+		data = ST_LSM6DSX_SHIFT_VAL(1, hub_settings->wr_once.mask);
+		err = st_lsm6dsx_shub_write_reg_with_mask(hw,
+			hub_settings->wr_once.addr,
+			hub_settings->wr_once.mask,
+			data);
+		if (err < 0)
+			return err;
+	}
+
 	slv_addr = ST_LSM6DSX_SLV_ADDR(0, hub_settings->slv0_addr);
 	config[0] = sensor->ext_info.addr << 1;
 	for (i = 0 ; i < len; i++) {
@@ -319,11 +351,54 @@ st_lsm6dsx_shub_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
 					       val);
 }
 
+/* use SLV{1,2,3} for FIFO read operations */
+static int
+st_lsm6dsx_shub_config_channels(struct st_lsm6dsx_sensor *sensor,
+				bool enable)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	u8 config[9] = {}, enable_mask, slv_addr;
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	struct st_lsm6dsx_sensor *cur_sensor;
+	int i, j = 0;
+
+	hub_settings = &hw->settings->shub_settings;
+	if (enable)
+		enable_mask = hw->enable_mask | BIT(sensor->id);
+	else
+		enable_mask = hw->enable_mask & ~BIT(sensor->id);
+
+	for (i = ST_LSM6DSX_ID_EXT0; i <= ST_LSM6DSX_ID_EXT2; i++) {
+		if (!hw->iio_devs[i])
+			continue;
+
+		cur_sensor = iio_priv(hw->iio_devs[i]);
+		if (!(enable_mask & BIT(cur_sensor->id)))
+			continue;
+
+		settings = cur_sensor->ext_info.settings;
+		config[j] = (sensor->ext_info.addr << 1) | 1;
+		config[j + 1] = settings->out.addr;
+		config[j + 2] = (settings->out.len & ST_LS6DSX_READ_OP_MASK) |
+				hub_settings->batch_en;
+		j += 3;
+	}
+
+	slv_addr = ST_LSM6DSX_SLV_ADDR(1, hub_settings->slv0_addr);
+	return st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+					 sizeof(config));
+}
+
 int st_lsm6dsx_shub_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable)
 {
 	const struct st_lsm6dsx_ext_dev_settings *settings;
 	int err;
 
+	err = st_lsm6dsx_shub_config_channels(sensor, enable);
+	if (err < 0)
+		return err;
+
 	settings = sensor->ext_info.settings;
 	if (enable) {
 		err = st_lsm6dsx_shub_set_odr(sensor, sensor->odr);