Some custom chips from this series require a wakeup sequence before the
measurement cycle is started.
Quote from the product datasheet:
"Optional sleep mode available upon special request."
Signed-off-by: Petre Rodan <petre.rodan@xxxxxxxxxxxxxxx>
---
drivers/iio/pressure/hsc030pa.c | 4 ++++
drivers/iio/pressure/hsc030pa.h | 4 ++++
drivers/iio/pressure/hsc030pa_i2c.c | 19 +++++++++++++++++
drivers/iio/pressure/hsc030pa_spi.c | 32 +++++++++++++++++++++++++++--
4 files changed, 57 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/pressure/hsc030pa.c b/drivers/iio/pressure/hsc030pa.c
index 3faa0fd42201..9e66fd561801 100644
--- a/drivers/iio/pressure/hsc030pa.c
+++ b/drivers/iio/pressure/hsc030pa.c
@@ -501,6 +501,10 @@ int hsc_common_probe(struct device *dev, hsc_recv_fn recv)
return dev_err_probe(dev, -EINVAL,
"pressure limits are invalid\n");
+ ret = device_property_read_bool(dev, "honeywell,sleep-mode");
+ if (ret)
+ hsc->capabilities |= HSC_CAP_SLEEP;
+
ret = devm_regulator_get_enable(dev, "vdd");
if (ret)
return dev_err_probe(dev, ret, "can't get vdd supply\n");
diff --git a/drivers/iio/pressure/hsc030pa.h b/drivers/iio/pressure/hsc030pa.h
index 6c635c42d85d..4e356944d67d 100644
--- a/drivers/iio/pressure/hsc030pa.h
+++ b/drivers/iio/pressure/hsc030pa.h
@@ -15,6 +15,8 @@
#define HSC_REG_MEASUREMENT_RD_SIZE 4
#define HSC_RESP_TIME_MS 2
+#define HSC_CAP_SLEEP 0x1
+
struct device;
struct iio_chan_spec;
@@ -29,6 +31,7 @@ typedef int (*hsc_recv_fn)(struct hsc_data *);
* struct hsc_data
* @dev: current device structure
* @chip: structure containing chip's channel properties
+ * @capabilities: chip specific attributes
* @recv_cb: function that implements the chip reads
* @is_valid: true if last transfer has been validated
* @pmin: minimum measurable pressure limit
@@ -45,6 +48,7 @@ typedef int (*hsc_recv_fn)(struct hsc_data *);
struct hsc_data {
struct device *dev;
const struct hsc_chip_data *chip;
+ u32 capabilities;
hsc_recv_fn recv_cb;
bool is_valid;
s32 pmin;
diff --git a/drivers/iio/pressure/hsc030pa_i2c.c b/drivers/iio/pressure/hsc030pa_i2c.c
index b3fd230e71da..62bdae272012 100644
--- a/drivers/iio/pressure/hsc030pa_i2c.c
+++ b/drivers/iio/pressure/hsc030pa_i2c.c
@@ -24,8 +24,27 @@ static int hsc_i2c_recv(struct hsc_data *data)
{
struct i2c_client *client = to_i2c_client(data->dev);
struct i2c_msg msg;
+ u8 buf;
int ret;
+ if (data->capabilities & HSC_CAP_SLEEP) {
+ /*
+ * Send the Full Measurement Request (FMR) command on the CS
+ * line in order to wake up the sensor as per
+ * "Sleep Mode for Use with Honeywell Digital Pressure Sensors"
+ * technical note (consult the datasheet link in the header).
+ *
+ * These specifications require a dummy packet comprised only by
+ * a single byte that contains the 7bit slave address and the
+ * READ bit followed by a STOP.
+ * Because the i2c API does not allow packets without a payload,
+ * the driver sends two bytes in this implementation.
+ */
+ ret = i2c_master_recv(client, &buf, 1);
+ if (ret < 0)
+ return ret;
+ }
+
msleep_interruptible(HSC_RESP_TIME_MS);
msg.addr = client->addr;
diff --git a/drivers/iio/pressure/hsc030pa_spi.c b/drivers/iio/pressure/hsc030pa_spi.c
index 737197eddff0..1c139cdfe856 100644
--- a/drivers/iio/pressure/hsc030pa_spi.c
+++ b/drivers/iio/pressure/hsc030pa_spi.c
@@ -25,12 +25,40 @@ static int hsc_spi_recv(struct hsc_data *data)
struct spi_device *spi = to_spi_device(data->dev);
struct spi_transfer xfer = {
.tx_buf = NULL,
- .rx_buf = data->buffer,
- .len = HSC_REG_MEASUREMENT_RD_SIZE,
+ .rx_buf = NULL,
+ .len = 0,
};
+ u16 orig_cs_setup_value;
+ u8 orig_cs_setup_unit;
+
+ if (data->capabilities & HSC_CAP_SLEEP) {
+ /*
+ * Send the Full Measurement Request (FMR) command on the CS
+ * line in order to wake up the sensor as per
+ * "Sleep Mode for Use with Honeywell Digital Pressure Sensors"
+ * technical note (consult the datasheet link in the header).
+ *
+ * These specifications require the CS line to be held asserted
+ * for at least 8µs without any payload being generated.
+ */
+ orig_cs_setup_value = spi->cs_setup.value;
+ orig_cs_setup_unit = spi->cs_setup.unit;
+ spi->cs_setup.value = 8;
+ spi->cs_setup.unit = SPI_DELAY_UNIT_USECS;
+ /*
+ * Send a dummy 0-size packet so that CS gets toggled.
+ * Trying to manually call spi->controller->set_cs() instead
+ * does not work as expected during the second call.
+ */
+ spi_sync_transfer(spi, &xfer, 1);
+ spi->cs_setup.value = orig_cs_setup_value;
+ spi->cs_setup.unit = orig_cs_setup_unit;
+ }
msleep_interruptible(HSC_RESP_TIME_MS);
+ xfer.rx_buf = data->buffer;
+ xfer.len = HSC_REG_MEASUREMENT_RD_SIZE;
return spi_sync_transfer(spi, &xfer, 1);
}
--
2.41.0
