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Message-ID: <20240112171356.00003e88@Huawei.com>
Date: Fri, 12 Jan 2024 17:13:56 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Petre Rodan <petre.rodan@...dimension.ro>
CC: <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Jonathan
Cameron" <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH 6/6] iio: pressure: hsc030pa add sleep mode
On Wed, 10 Jan 2024 19:22:41 +0200
Petre Rodan <petre.rodan@...dimension.ro> wrote:
> 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@...dimension.ro>
> ---
> 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;
if (device_property_read_bool())
hsc->cap...
The return value is not an int so it's inappropriate to stash it in ret.
> +
> 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.
> + */
Do you have a reference that says the CS must be toggled on 0 length transfer?
If that's not specified in the SPI core somewhere then you will need to send
something...
> + 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
>
>
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