Re: [PATCH v8 3/3] iio: proximity: Add driver support for TYHX's HX9023S capacitive proximity sensor

From: Yasin Lee
Date: Tue Jul 02 2024 - 08:32:22 EST


On 2024/6/30 02:41, Jonathan Cameron wrote:
On Tue, 25 Jun 2024 23:58:54 +0800
Yasin Lee <yasin.lee.x@xxxxxxxxx> wrote:

A SAR sensor from NanjingTianyihexin Electronics Ltd.

The device has the following entry points:

Usual frequency:
- sampling_frequency

Instant reading of current values for different sensors:
- in_proximity0_raw
- in_proximity1_raw
- in_proximity2_raw
- in_proximity3_raw
- in_proximity4_raw
and associated events in events/

Signed-off-by: Yasin Lee <yasin.lee.x@xxxxxxxxx>
Hi Yasin

Definitely getting close to ready to merge.
A few bits of review feedback inline to resolve.

Jonathan


Hi Jonathan,


Thank you very much for your patient guidance and encouragement. I have made modifications and responses to each comment. Please review version V9.

Best regards,

Yasin


diff --git a/drivers/iio/proximity/hx9023s.c b/drivers/iio/proximity/hx9023s.c
new file mode 100644
index 000000000000..c455f20d784f
--- /dev/null
+++ b/drivers/iio/proximity/hx9023s.c
@@ -0,0 +1,1131 @@
+
+#define HX9023S_CHIP_ID 0x1D
+#define HX9023S_CH_NUM 5
+#define HX9023S_2BYTES 2
+#define HX9023S_3BYTES 3
Don't use defines where the number is actually more meaningful
when seen in the code.

+#define HX9023S_BYTES_MAX HX9023S_3BYTES
This define is useful but just make it 3.


These three macro definitions will be deleted in version V9.


+struct hx9023s_ch_data {
+ int raw; /* Raw Data*/
+ int lp; /* Low Pass Filter Data*/
+ int bl; /* Base Line Data */
+ int diff; /* difference of Low Pass Data and Base Line Data */
Difference

for consistency of capitalizaton.


Fixed in v9.


+static int hx9023s_ch_cfg(struct hx9023s_data *data)
+{
+ unsigned int i;
+ u16 reg;
+ u8 reg_list[HX9023S_CH_NUM * 2];
+ u8 ch_pos[HX9023S_CH_NUM];
+ u8 ch_neg[HX9023S_CH_NUM];
+ /* Bit positions corresponding to input pin connections */
+ u8 conn_cs[HX9023S_CH_NUM] = {0, 2, 4, 6, 8};
Space after { and before }


Fixed in v9.


+
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ ch_pos[i] = data->ch_data[i].channel_positive == HX9023S_NOT_CONNECTED ?
+ HX9023S_NOT_CONNECTED : conn_cs[data->ch_data[i].channel_positive];
+ ch_neg[i] = data->ch_data[i].channel_negative == HX9023S_NOT_CONNECTED ?
+ HX9023S_NOT_CONNECTED : conn_cs[data->ch_data[i].channel_negative];
+
+ reg = (HX9023S_POS << ch_pos[i]) | (HX9023S_NEG << ch_neg[i]);
+ put_unaligned_le16(reg, &reg_list[i * 2]);
+ }
+
+ return regmap_bulk_write(data->regmap, HX9023S_CH0_CFG_7_0, reg_list, HX9023S_CH_NUM * 2);
+}
+
+static int hx9023s_sample(struct hx9023s_data *data)
+{
+ int ret, value;
+ unsigned int i;
+ u8 data_size, offset_data_size, *p, size, rx_buf[HX9023S_CH_NUM * HX9023S_BYTES_MAX];
Long line combining different data types. Break them up to improve readability.

u8 rx_buf[HX9023S_CH_NUM * HX9023S_BYTES_MAX];
u8 data_size, offset_data_size, size;
u8 *p;


Delete: data_size, offset_data_size, *p, size.


+
+ ret = hx9023s_data_lock(data, true);
+ if (ret)
+ return ret;
+
+ ret = hx9023s_data_select(data);
+ if (ret)
+ goto err;
+
+ data_size = HX9023S_3BYTES;
This local variable hurts readabilty.


Deleted.


+
+ /* ch0~ch3 */
+ p = rx_buf;
Why local variable?


Deleted.


+ size = (HX9023S_CH_NUM - 1) * data_size;
This is non obvious sizing. Here a comment is appropriate.

/* 3 bytes for each of channels 0 to 3 which have contiguous registers */

+ ret = regmap_bulk_read(data->regmap, HX9023S_RAW_BL_CH0_0, p, size);
Combining above comments.

ret = regmap_bulk_read(data->regmap, HX9023S_RAW_BL_CH0_0, &rx_buf, size);

+ if (ret)
+ goto err;
+
+ /* ch4 */
+ p = rx_buf + size;
+ size = data_size;
Here as well provide a comment on the fact the channel is 3 contiguous registers.


Added concise comments as suggested, deleted excessive macro definitions, and used direct numbers for clarity.


+ ret = regmap_bulk_read(data->regmap, HX9023S_RAW_BL_CH4_0, p, size);
+ if (ret)
+ goto err;
+
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ value = get_unaligned_le16(&rx_buf[i * data_size + 1]);
This seems odd. From the datasheet I found seems there are some bits in
the ch0_0 register as well. Why just pull out 16 bits?

I would use a get_unaligned_le24() call to get the rest and then rely on
shift for userspace to drop bits 3:0

It it makes sense to just provide the top 16 bits thats fine.


Based on the chip designer's explanation, the lower 8-bit data is almost meaningless, and users are advised to use only the upper 16-bit data. Therefore, I kept get_unaligned_le16().


+ value = sign_extend32(value, 15);
Why use int to store an s16? If you just use an s16 for value then no
need to sign extend and then store that into an s16 .raw in the channel
data structure.


Using int is incorrect. I will take your advice, delete sign_extend32, and directly store the data in s16.


+ data->ch_data[i].raw = 0;
+ data->ch_data[i].bl = 0;
+ if (data->ch_data[i].sel_raw)
+ data->ch_data[i].raw = value;
+ if (data->ch_data[i].sel_bl)
+ data->ch_data[i].bl = value;
+ }
+
+ /* ch0~ch3 */
+ p = rx_buf;
+ size = (HX9023S_CH_NUM - 1) * data_size;
As above - use a comment to explain why this is 12 then just use 12.
Current form is far form obvious.


I will take this suggestion and update it in V9.


+ ret = regmap_bulk_read(data->regmap, HX9023S_LP_DIFF_CH0_0, p, size);
+ if (ret)
+ goto err;
+
+ /* ch4 */
+ p = rx_buf + size;
+ size = data_size;
+ ret = regmap_bulk_read(data->regmap, HX9023S_LP_DIFF_CH4_0, p, size);
+ if (ret)
+ goto err;
+
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ value = get_unaligned_le16(&rx_buf[i * data_size + 1]);
+ value = sign_extend32(value, 15);
+ data->ch_data[i].lp = 0;
+ data->ch_data[i].diff = 0;
+ if (data->ch_data[i].sel_lp)
+ data->ch_data[i].lp = value;
+ if (data->ch_data[i].sel_diff)
+ data->ch_data[i].diff = value;
+ }
+
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ if (data->ch_data[i].sel_lp && data->ch_data[i].sel_bl)
+ data->ch_data[i].diff = data->ch_data[i].lp - data->ch_data[i].bl;
+ }
+
+ /* offset DAC */
+ offset_data_size = HX9023S_2BYTES;
+ p = rx_buf;
+ size = HX9023S_CH_NUM * offset_data_size;
+ ret = regmap_bulk_read(data->regmap, HX9023S_OFFSET_DAC0_7_0, p, size);
+ if (ret)
+ goto err;
+
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ value = get_unaligned_le16(&rx_buf[i * offset_data_size]);
+ value = FIELD_GET(GENMASK(11, 0), value);
+ data->ch_data[i].dac = value;
+ }
+
+err:
+ return hx9023s_data_lock(data, false);
+}

+
+static int hx9023s_property_get(struct hx9023s_data *data)
+{
+ struct fwnode_handle *child;
+ struct device *dev = regmap_get_device(data->regmap);
+ int ret;
+ u32 i, reg, temp, array[2];
+
+ data->chan_in_use = 0;
+ for (i = 0; i < HX9023S_CH_NUM; i++) {
+ data->ch_data[i].channel_positive = HX9023S_NOT_CONNECTED;
+ data->ch_data[i].channel_negative = HX9023S_NOT_CONNECTED;
+ }
+
+ device_for_each_child_node(dev, child) {
Use
device_for_each_child_node_scoped(dev, child) {
As then no need to call fwnode_handle_put() in error paths.


I will take this suggestion and update it in V9.


+ ret = fwnode_property_read_u32(child, "reg", &reg);
+ if (ret || reg >= HX9023S_CH_NUM) {
+ fwnode_handle_put(child);
+ return dev_err_probe(dev, ret, "Failed to read reg\n");
+ }
+ __set_bit(reg, &data->chan_in_use);
+
+ if (fwnode_property_read_u32(child, "input-channel", &temp) == 0) {
+ data->ch_data[reg].channel_positive = temp;
+ data->ch_data[reg].channel_negative = HX9023S_NOT_CONNECTED;
+ } else if (fwnode_property_read_u32_array(child, "diff-channels",
+ array, sizeof(array)) == 0) {
+ data->ch_data[reg].channel_positive = array[0];
+ data->ch_data[reg].channel_negative = array[1];
+ } else {
+ fwnode_handle_put(child);
+ return dev_err_probe(dev, ret,
+ "Failed to read channel input for channel %d\n", reg);
+ }
+ }
+
+ return 0;
+}

+
+static void hx9023s_push_events(struct iio_dev *indio_dev)
+{
+ struct hx9023s_data *data = iio_priv(indio_dev);
+ s64 timestamp = iio_get_time_ns(indio_dev);
+ unsigned long prox_changed;
+ unsigned int chan;
+
+ hx9023s_sample(data);
check the return codes for these calls that involve bus transactions.
If they fail, just return form this function having not pushed an event.

Otherwise we may push stale data.


Fixed in v9


+ hx9023s_get_prox_state(data);
+
+ prox_changed = (data->chan_prox_stat ^ data->prox_state_reg) & data->chan_event;
+ for_each_set_bit(chan, &prox_changed, HX9023S_CH_NUM) {
+ unsigned int dir;
+
+ dir = (data->prox_state_reg & BIT(chan)) ? IIO_EV_DIR_FALLING : IIO_EV_DIR_RISING;
+
+ iio_push_event(indio_dev,
+ IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, chan, IIO_EV_TYPE_THRESH, dir),
+ timestamp);
+ }
+ data->chan_prox_stat = data->prox_state_reg;
+}





+static int hx9023s_id_check(struct iio_dev *indio_dev)
+{
+ struct hx9023s_data *data = iio_priv(indio_dev);
+ int ret;
+ unsigned int id;
+
+ ret = regmap_read(data->regmap, HX9023S_DEVICE_ID, &id);
+ if (ret || id != HX9023S_CHIP_ID)
+ return -ENODEV;
This breaks the use of callback compatible IDs in future. It is only
appropriate to print a warning on an unknown ID .
Also don't eat the error value returned - it may provide a useful hint
of a problem.

if (ret)
return ret;

if (id != HX9023S_CHIP_ID)
dev_warn(&indio_dev->dev.parent,
"Unexpected chip ID, assuming compatible\n");

return 0;

there are lots of older drivers where we did this wrong. We tend to
repair this when otherwise working on a driver, so it will take a
while before they are all fixed.


I will take this suggestion and update it in V9.


+
+ return 0;
+}
+
+static int hx9023s_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct iio_dev *indio_dev;
+ struct hx9023s_data *data;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(struct hx9023s_data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_dev);
+ mutex_init(&data->mutex);
+
+ data->regmap = devm_regmap_init_i2c(client, &hx9023s_regmap_config);
+ if (IS_ERR(data->regmap))
+ return dev_err_probe(dev, PTR_ERR(data->regmap), "regmap init failed\n");
+
+ ret = hx9023s_property_get(data);
+ if (ret)
+ return dev_err_probe(dev, ret, "dts phase failed\n");
+
+ ret = devm_regulator_get_enable(dev, "vdd");
+ if (ret)
+ return dev_err_probe(dev, ret, "regulator get failed\n");
+
+ ret = hx9023s_id_check(indio_dev);
+ if (ret)
+ return dev_err_probe(dev, ret, "id check failed\n");
As commented on above, this should not fail on a missmatch ont he ID, just
on a failure to read it at all. That enables future devices that haven't
been made yet and happen to be compatible to be able to work with older
linux kernels that predate them.


Understood, thank you very much for your detailed explanation.


+}