Re: [PATCH v6 2/2] iio: proximity: vl53l0x: add interrupt support

From: Jonathan Cameron
Date: Sat Sep 22 2018 - 11:05:32 EST

On Tue, 18 Sep 2018 16:24:22 +0800
Song Qiang <songqiang1304521@xxxxxxxxx> wrote:

> The first version of this driver issues a measuring request and polling
> for a status register in the device for measuring completes.
> vl53l0x support configuring GPIO1 on it to generate interrupt to
> indicate that new measurement is ready. This patch adds support for
> using this mechanisim to reduce cpu cost.
>
> Signed-off-by: Song Qiang <songqiang1304521@xxxxxxxxx>
Hi Song.

Looks correct in principal but a few things to tidy up before
this is ready to apply.

Also we have an unrelated change in here to check the devices ID.
That should be in it's own patch.

Thanks,

Jonathan
> ---
> .../bindings/iio/proximity/vl53l0x.txt | 14 +-
> drivers/iio/proximity/vl53l0x-i2c.c | 135 +++++++++++++++---
> 2 files changed, 129 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> index ab9a9539fec4..40290f8dd70f 100644
> --- a/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> +++ b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> @@ -4,9 +4,21 @@ Required properties:
> - compatible: must be "st,vl53l0x-i2c"
> - reg: i2c address where to find the device
>
> +Optional properties:
> + - interrupts : Interrupt line receiving GPIO1's measuring complete
> + output, supports IRQ_TYPE_EDGE_FALLING only.
> +
> + Refer to interrupt-controller/interrupts.txt for generic
> + interrupt client node bindings.
> +
> Example:
>
> vl53l0x@29 {
> + pinctrl-names = "default";
> + pinctrl-0 = <&vl53l0x_pins>;
> +
Please drop this from the example. This is board specific rather than
being generally required.

> compatible = "st,vl53l0x-i2c";
> reg = <0x29>;
> -};
> + interrupt-parent = <&gpio3>;
> + interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
> +}
> diff --git a/drivers/iio/proximity/vl53l0x-i2c.c b/drivers/iio/proximity/vl53l0x-i2c.c
> index 1aad45df8d95..a5cff11f41de 100644
> --- a/drivers/iio/proximity/vl53l0x-i2c.c
> +++ b/drivers/iio/proximity/vl53l0x-i2c.c
> @@ -10,18 +10,21 @@
> *
> * Default 7-bit i2c slave address 0x29.
> *
> - * TODO: FIFO buffer, continuous mode, interrupts, range selection,
> - * sensor ID check.
> + * TODO: FIFO buffer, continuous mode, range selection.
> */
>
> #include <linux/module.h>
> #include <linux/i2c.h>
> #include <linux/delay.h>
> +#include <linux/interrupt.h>
>
> #include <linux/iio/iio.h>
>
> +#include <stdbool.h>
> +
> #define VL_REG_SYSRANGE_START 0x00
>
> +/* Mode configuration registers. */
> #define VL_REG_SYSRANGE_MODE_MASK GENMASK(3, 0)
> #define VL_REG_SYSRANGE_MODE_SINGLESHOT 0x00
> #define VL_REG_SYSRANGE_MODE_START_STOP BIT(0)
> @@ -29,14 +32,61 @@
> #define VL_REG_SYSRANGE_MODE_TIMED BIT(2)
> #define VL_REG_SYSRANGE_MODE_HISTOGRAM BIT(3)
>
> +/* Result registers. */
> #define VL_REG_RESULT_INT_STATUS 0x13
> #define VL_REG_RESULT_RANGE_STATUS 0x14
> #define VL_REG_RESULT_RANGE_STATUS_COMPLETE BIT(0)
>
> +/* GPIO function configuration registers. */
> +#define VL_REG_GPIO_HV_MUX_ACTIVE_GIGH 0x84
> +#define VL_REG_SYS_INT_CFG_GPIO 0x0A
> +#define VL_GPIOFUNC_NEW_MEASURE_RDY BIT(2)
> +
> +/* Interrupt configuration registers. */
> +#define VL_REG_SYS_INT_CLEAR 0x0B
> +#define VL_REG_RESULT_INT_STATUS 0x13
> +#define VL_INT_POLARITY_LOW 0x00
> +#define VL_INT_POLARITY_HIGH BIT(0)
> +
> +/* Should be 0xEE if connection is fine. */
> +#define VL_REG_MODEL_ID 0xC0
> +
> struct vl53l0x_data {
> struct i2c_client *client;
> + struct completion measuring_done;
> + bool use_interrupt;
> };
>
> +static int vl53l0x_clear_interrupt(struct vl53l0x_data *data)
> +{
> + int ret;
> + u8 cnt = 0;
> +
> + do {
> + /* bit 0 for measuring interrupt, bit 1 for error interrupt. */
> + i2c_smbus_write_byte_data(data->client,
> + VL_REG_SYS_INT_CLEAR, 1);

All these i2c comms need checking for errors. I2c buses aren't always the most
reliable things.

> + i2c_smbus_write_byte_data(data->client,
> + VL_REG_SYS_INT_CLEAR, 0);
> + ret = i2c_smbus_read_byte_data(data->client,
> + VL_REG_RESULT_INT_STATUS);
> + cnt++;
> + } while ((ret & 0x07) && (cnt < 3));
> + if (cnt > 2)
> + return -ETIMEDOUT;
> + else
> + return 0;
> +}
> +
> +static irqreturn_t vl53l0x_irq_handler(int irq, void *d)
> +{
> + struct vl53l0x_data *data = d;
> +
> + complete(&data->measuring_done);
> +
> + return IRQ_HANDLED;
> +}
> +
> static int vl53l0x_read_proximity(struct vl53l0x_data *data,
> const struct iio_chan_spec *chan,
> int *val)
> @@ -46,23 +96,31 @@ static int vl53l0x_read_proximity(struct vl53l0x_data *data,
> u8 buffer[12];
> int ret;
>
> - ret = i2c_smbus_write_byte_data(client, VL_REG_SYSRANGE_START, 1);
> - if (ret < 0)
> - return ret;
> -
> - do {
> - ret = i2c_smbus_read_byte_data(client,
> - VL_REG_RESULT_RANGE_STATUS);
> - if (ret < 0)
> - return ret;
> -
> - if (ret & VL_REG_RESULT_RANGE_STATUS_COMPLETE)
> - break;
> -
> - usleep_range(1000, 5000);
> - } while (--tries);
> - if (!tries)
> - return -ETIMEDOUT;
> + if (data->use_interrupt)
> + reinit_completion(&data->measuring_done);

This seems a little strange. Should be initialized already on first
pass for example. I don't suppose it matters, but feels a bit odd.
You may need to protect against multiple concurrent readers however...

> +
> + i2c_smbus_write_byte_data(client, VL_REG_SYSRANGE_START, 1);
> +
> + /* In usual case the longest valid conversion time is less than 70ms. */
> + if (data->use_interrupt) {
> + ret = wait_for_completion_timeout(&data->measuring_done,
> + msecs_to_jiffies(100));
> + if (!ret)
> + return -ETIMEDOUT;
> + vl53l0x_clear_interrupt(data);
> + } else {
> + do {
> + ret = i2c_smbus_read_byte_data(client,
> + VL_REG_RESULT_RANGE_STATUS);
> +
> + if (ret & VL_REG_RESULT_RANGE_STATUS_COMPLETE)
> + break;
> +
> + usleep_range(1000, 5000);
> + } while (--tries);
> + if (!tries)
> + return -ETIMEDOUT;
> + }
>
> ret = i2c_smbus_read_i2c_block_data(client, VL_REG_RESULT_RANGE_STATUS,
> 12, buffer);
> @@ -110,10 +168,21 @@ static const struct iio_info vl53l0x_info = {
> .read_raw = vl53l0x_read_raw,
> };
>
> +/* Congigure the GPIO1 pin to generate interrupt for measurement ready,
Comment syntax + spell check. Configure For a description like this
nicer to have it in kernel-doc style as well rather than a freeform comment.

> + * default polarity is level low.
> + */
> +static int vl53l0x_config_irq(struct vl53l0x_data *data)
> +{
> + i2c_smbus_write_byte_data(data->client, VL_REG_SYS_INT_CFG_GPIO,
> + VL_GPIOFUNC_NEW_MEASURE_RDY);

Error checking on that write_byte?

> + return vl53l0x_clear_interrupt(data);
> +}
> +
> static int vl53l0x_probe(struct i2c_client *client)
> {
> struct vl53l0x_data *data;
> struct iio_dev *indio_dev;
> + int ret;
>
> indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> if (!indio_dev)
> @@ -134,6 +203,34 @@ static int vl53l0x_probe(struct i2c_client *client)
> indio_dev->num_channels = ARRAY_SIZE(vl53l0x_channels);
> indio_dev->modes = INDIO_DIRECT_MODE;
>
> + if (!client->irq)
> + data->use_interrupt = false;
> + else {
> + data->use_interrupt = true;
> + ret = devm_request_irq(&client->dev,
> + client->irq,
> + vl53l0x_irq_handler,
> + IRQF_TRIGGER_FALLING,
> + indio_dev->name,
> + data);
> + if (ret < 0) {
> + dev_err(&client->dev,

Lots of odd alignment in here. Please tidy up.

> + "request irq line failed.");
> + return -EINVAL;
> + }
> + vl53l0x_config_irq(data);
> + init_completion(&data->measuring_done);
> + }
> +
> + /* After checking this, assuming write and read byte operations should
/*
* After..
*/
> + * never fails.
> + */
> + ret = i2c_smbus_read_byte_data(client, VL_REG_MODEL_ID);
> + if (ret != 0xEE) {
> + dev_err(&client->dev, "device not found. ");
No space after . and \n is normal for a dev_err message.

What does this have to do with interrupt support?

Please break it out as a separate patch.

> + return -EREMOTEIO;
> + }
> +
> return devm_iio_device_register(&client->dev, indio_dev);
> }
>