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SubjectRe: [PATCH v2 1/4] HID: hid-sensor-custom: Add custom sensor iio support
On Thu, 19 Nov 2020 18:03:28 +0800
Ye Xiang <xiang.ye@intel.com> wrote:

> Currently custom sensors properties are not decoded and it is up to
> user space to interpret.
>
> Some manufacturers already standardized the meaning of some custom sensors.
> They can be presented as a proper IIO sensor. We can identify these sensors
> based on manufacturer and serial number property in the report.
>
> This change is identifying hinge sensor when the manufacturer is "INTEL".
> This creates a platform device so that a sensor driver can be loaded to
> process these sensors.
>
> Signed-off-by: Ye Xiang <xiang.ye@intel.com>

Hi Ye Xiang,

Various comments inline.

Thanks,

Jonathan

> ---
> drivers/hid/hid-sensor-custom.c | 170 ++++++++++++++++++++++++++++++++
> include/linux/hid-sensor-ids.h | 39 ++++++++
> 2 files changed, 209 insertions(+)
>
> diff --git a/drivers/hid/hid-sensor-custom.c b/drivers/hid/hid-sensor-custom.c
> index 4d25577a8573..bb96d9c09daf 100644
> --- a/drivers/hid/hid-sensor-custom.c
> +++ b/drivers/hid/hid-sensor-custom.c
> @@ -4,6 +4,7 @@
> * Copyright (c) 2015, Intel Corporation.
> */
>
> +#include <linux/ctype.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/init.h>
> @@ -21,6 +22,7 @@
> #define HID_CUSTOM_TOTAL_ATTRS (HID_CUSTOM_MAX_CORE_ATTRS + 1)
> #define HID_CUSTOM_FIFO_SIZE 4096
> #define HID_CUSTOM_MAX_FEATURE_BYTES 64
> +#define HID_SENSOR_USAGE_LENGTH (4 + 1)
>
> struct hid_sensor_custom_field {
> int report_id;
> @@ -50,6 +52,8 @@ struct hid_sensor_custom {
> struct kfifo data_fifo;
> unsigned long misc_opened;
> wait_queue_head_t wait;
> + struct platform_device *custom_pdev;
> + bool custom_pdev_exposed;
> };
>
> /* Header for each sample to user space via dev interface */
> @@ -746,11 +750,159 @@ static void hid_sensor_custom_dev_if_remove(struct hid_sensor_custom
>
> }
>
> +/*
> + * use sensors luid which is defined in FW, such as ISH,
> + * to identify sensor.
> + */

const?

> +static char *known_sensor_luid[] = { "020B000000000000" };
> +
> +static int get_luid_table_index(unsigned char *usage_str)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(known_sensor_luid); i++) {
> + if (!strncmp(usage_str, known_sensor_luid[i],
> + strlen(known_sensor_luid[i])))
> + return i;
> + }
> +
> + return -1;
> +}
> +
> +static int get_known_custom_sensor_index(struct hid_sensor_hub_device *hsdev)
> +{
> + struct hid_sensor_hub_attribute_info sensor_manufacturer = { 0 };
> + struct hid_sensor_hub_attribute_info sensor_luid_info = { 0 };
> + int report_size;
> + int ret;
> + u16 *w_buf;
> + int w_buf_len;
> + char *buf;
> + int buf_len;
> + int i;
> + int index;
> +
> + w_buf_len = sizeof(u16) * HID_CUSTOM_MAX_FEATURE_BYTES;
> + buf_len = sizeof(char) * HID_CUSTOM_MAX_FEATURE_BYTES;
Given these are compile time values, these two could just go
directly above with no loss of readability.

int w_buf_len = siezof(u16)...

> + w_buf = kzalloc(w_buf_len, GFP_KERNEL);
> + if (!w_buf)
> + return -1;

Better to return meaningful error values and if the error
isn't just 'didn't find it' - probably -ENODEV and we should check that
was the cause of the problem at the call site for this function.
If it was a memory allocation error we should quit out instead of trying
something else.

> +
> + buf = kzalloc(buf_len, GFP_KERNEL);
> + if (!buf) {
> + kfree(w_buf);
Given we have error handling for this below, better to be consistent
and use a goto + an additional error label for htis case.

> + return -1;
> + }
> +
> + /* get manufacturer info */
> + ret = sensor_hub_input_get_attribute_info(
> + hsdev, HID_FEATURE_REPORT, hsdev->usage,
> + HID_USAGE_SENSOR_PROP_MANUFACTURER, &sensor_manufacturer);
> + if (ret < 0)

From HID point of view, is that allowed to fail? Probably best to add
a comment to say if it is or isn't.
I'd like to be able to read this code and know which of these error paths
just means we don't have a matching sensor.

> + goto err_out;
> +
> + report_size =
> + sensor_hub_get_feature(hsdev, sensor_manufacturer.report_id,
> + sensor_manufacturer.index, w_buf_len,
> + w_buf);
> + if (report_size <= 0) {
> + hid_err(hsdev->hdev,
> + "Failed to get sensor manufacturer info %d\n",
> + report_size);
> + goto err_out;
> + }
> +
> + /* convert from wide char to char */
> + for (i = 0; i < buf_len - 1 && w_buf[i]; i++)
> + buf[i] = (char)w_buf[i];
> +
> + /* ensure it's ISH sensor */
> + if (strncmp(buf, "INTEL", strlen("INTEL")))
> + goto err_out;
> +
> + memset(w_buf, 0, w_buf_len);
> + memset(buf, 0, buf_len);
> +
> + /* get real usage id */
> + ret = sensor_hub_input_get_attribute_info(
> + hsdev, HID_FEATURE_REPORT, hsdev->usage,
> + HID_USAGE_SENSOR_PROP_SERIAL_NUM, &sensor_luid_info);
> + if (ret < 0)
> + goto err_out;
> +
> + report_size = sensor_hub_get_feature(hsdev, sensor_luid_info.report_id,
> + sensor_luid_info.index, w_buf_len,
> + w_buf);
> + if (report_size <= 0) {
> + hid_err(hsdev->hdev, "Failed to get real usage info %d\n",
> + report_size);
> + goto err_out;
> + }
> +
> + /* convert from wide char to char */
> + for (i = 0; i < buf_len - 1 && w_buf[i]; i++)
> + buf[i] = (char)w_buf[i];
> +
> + if (strlen(buf) != strlen(known_sensor_luid[0]) + 5) {
> + hid_err(hsdev->hdev,
> + "%s luid length not match %zu != (%zu + 5)\n", __func__,
> + strlen(buf), strlen(known_sensor_luid[0]));
> + goto err_out;
> + }
> +
> + /* get table index with luid (not matching 'LUID: ' in luid) */
> + index = get_luid_table_index(&buf[5]);

Nicer to share the code block here with the error / unwind path below.
Particular as index might be -1 and hence an error.

> + kfree(w_buf);
> + kfree(buf);
> + return index;
> +
> +err_out:
> + kfree(w_buf);
> + kfree(buf);
> + return -1;
> +}
> +
> +static struct platform_device *
> +register_platform_device(struct platform_device *pdev,

Function needs a prefix as that sounds very generic.
When I saw it below, I assumed it was a generic call not
one in this file.

> + struct hid_sensor_hub_device *hsdev, int index)
> +{
> + char real_usage[HID_SENSOR_USAGE_LENGTH] = { 0 };
> + struct platform_device *custom_pdev;
> + const char *dev_name;
> + char *c;
> + int ret;
> +
> + /* copy real usage id */
> + memcpy(real_usage, known_sensor_luid[index], 4);
> +
> + /* usage id are all lowcase */
> + for (c = real_usage; *c != '\0'; c++)
> + *c = tolower(*c);
> +
> + /* HID-SENSOR-INT-REAL_USAGE_ID */
> + dev_name = kasprintf(GFP_KERNEL, "HID-SENSOR-INT-%s", real_usage);
> + if (!dev_name)
> + return NULL;
> +
> + custom_pdev = platform_device_register_data(pdev->dev.parent, dev_name,
> + PLATFORM_DEVID_NONE, hsdev,
> + sizeof(*hsdev));
> + kfree(dev_name);
> + ret = PTR_ERR_OR_ZERO(custom_pdev);
> + if (ret) {
> + dev_err(&pdev->dev, "platform_device_register_data failed ret:%d\n", ret);
> + return NULL;
> + }
> +
> + return custom_pdev;
> +}
> +
> static int hid_sensor_custom_probe(struct platform_device *pdev)
> {
> struct hid_sensor_custom *sensor_inst;
> struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> int ret;
> + int index;
>
> sensor_inst = devm_kzalloc(&pdev->dev, sizeof(*sensor_inst),
> GFP_KERNEL);
> @@ -764,6 +916,19 @@ static int hid_sensor_custom_probe(struct platform_device *pdev)
> sensor_inst->pdev = pdev;
> mutex_init(&sensor_inst->mutex);
> platform_set_drvdata(pdev, sensor_inst);
> +
> + index = get_known_custom_sensor_index(hsdev);
> + if (index >= 0) {
> + sensor_inst->custom_pdev =
> + register_platform_device(pdev, hsdev, index);
> + if (sensor_inst->custom_pdev) {
> + sensor_inst->custom_pdev_exposed = true;
> + return 0;
> + }
> +
> + dev_err(&pdev->dev, "register_platform_device failed\n");

This feels like somewhat odd logic. We aren't looking at a fallback for
something that is expected to fail so it doesn't make sense to carry
on.


> + }
> +
> ret = sensor_hub_register_callback(hsdev, hsdev->usage,
> &sensor_inst->callbacks);
> if (ret < 0) {
> @@ -802,6 +967,11 @@ static int hid_sensor_custom_remove(struct platform_device *pdev)
> struct hid_sensor_custom *sensor_inst = platform_get_drvdata(pdev);
> struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
>
> + if (sensor_inst->custom_pdev_exposed) {
> + platform_device_unregister(sensor_inst->custom_pdev);
> + return 0;
> + }
> +
> hid_sensor_custom_dev_if_remove(sensor_inst);
> hid_sensor_custom_remove_attributes(sensor_inst);
> sysfs_remove_group(&sensor_inst->pdev->dev.kobj,
> diff --git a/include/linux/hid-sensor-ids.h b/include/linux/hid-sensor-ids.h
> index 530c09f3e64a..46db3056f04b 100644
> --- a/include/linux/hid-sensor-ids.h
> +++ b/include/linux/hid-sensor-ids.h
> @@ -128,6 +128,10 @@
> #define HID_USAGE_SENSOR_UNITS_DEGREES_PER_SECOND 0x15
>
> /* Common selectors */
> +#define HID_USAGE_SENSOR_PROP_DESC 0x200300
> +#define HID_USAGE_SENSOR_PROP_FRIENDLY_NAME 0x200301
> +#define HID_USAGE_SENSOR_PROP_SERIAL_NUM 0x200307
> +#define HID_USAGE_SENSOR_PROP_MANUFACTURER 0x200305
> #define HID_USAGE_SENSOR_PROP_REPORT_INTERVAL 0x20030E
> #define HID_USAGE_SENSOR_PROP_SENSITIVITY_ABS 0x20030F
> #define HID_USAGE_SENSOR_PROP_SENSITIVITY_RANGE_PCT 0x200310
> @@ -159,4 +163,39 @@
> #define HID_USAGE_SENSOR_PROP_REPORTING_STATE_NO_EVENTS_ENUM 0x200840
> #define HID_USAGE_SENSOR_PROP_REPORTING_STATE_ALL_EVENTS_ENUM 0x200841
>
> +/* Custom Sensor (2000e1) */
> +#define HID_USAGE_SENSOR_HINGE 0x20020B
> +#define HID_USAGE_SENSOR_DATA_FIELD_LOCATION 0x200400
> +#define HID_USAGE_SENSOR_DATA_FIELE_TIME_SINCE_SYS_BOOT 0x20052B
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_USAGE 0x200541
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE 0x200543
Given these are all defined in a block could we use a macro?
HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE(x) 0x200543 + (x)

perhaps?

I'm not sure what the preferred convention is in this file.

> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_1 0x200544
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_2 0x200545
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_3 0x200546
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_4 0x200547
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_5 0x200548
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_6 0x200549
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_7 0x20054A
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_8 0x20054B
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_9 0x20054C
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_10 0x20054D
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_11 0x20054E
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_12 0x20054F
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_13 0x200550
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_14 0x200551
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_15 0x200552
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_16 0x200553
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_17 0x200554
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_18 0x200555
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_19 0x200556
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_20 0x200557
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_21 0x200558
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_22 0x200559
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_23 0x20055A
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_24 0x20055B
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_25 0x20055C
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_26 0x20055D
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_27 0x20055E
> +#define HID_USAGE_SENSOR_DATA_FIELD_CUSTOM_VALUE_28 0x20055F
> +
> #endif

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