[PATCH v4 4/7] iio: adc: hx711: introduce hx711_chip_info per-variant structure

[Piyush Patle <piyushpatle228@gmail.com>]

Add struct hx711_chip_info to hold per-variant static configuration:
device name, IIO channel spec array, IIO info ops pointer, and channel
count. Store a chip_info pointer in hx711_data and populate indio_dev
fields from it at probe time instead of hardcoding them.

Use device_get_match_data() to look up the chip_info pointer from the
of_device_id table. Guard against a NULL return so that the driver
fails cleanly if probed via the platform name match path without
associated match data.

No functional change for existing HX711 users.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
Changes in v4:
- New patch. Split out from the v3 refactor patch as requested by
  Andy Shevchenko.
- Place hx711_chip_info fields in their final order from the start so
  that the HX710B support patch (which adds fixed_gain/fixed_gain_val)
  appends new fields without reordering existing ones.
- Add NULL guard on device_get_match_data() return value to handle the
  platform alias match path that can bind without match data.
---
 drivers/iio/adc/hx711.c | 38 +++++++++++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 32362771cfc8..2a6e9645f54d 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -76,6 +76,20 @@ static int hx711_get_scale_to_gain(const int *gain_scale, int scale)
 	return -EINVAL;
 }
 
+/**
+ * struct hx711_chip_info - per-variant static configuration
+ * @name:         IIO device name
+ * @channels:     channel specification array
+ * @iio_info:     IIO info ops for this variant
+ * @num_channels: number of entries in @channels
+ */
+struct hx711_chip_info {
+	const char			*name;
+	const struct iio_chan_spec	*channels;
+	const struct iio_info		*iio_info;
+	unsigned int			num_channels;
+};
+
 struct hx711_data {
 	struct device		*dev;
 	struct gpio_desc	*gpiod_pd_sck;
@@ -83,6 +97,7 @@ struct hx711_data {
 	int			gain_set;	/* gain set on device */
 	int			gain_chan_a;	/* gain for channel A */
 	int			gain_scale[HX711_GAIN_MAX];
+	const struct hx711_chip_info	*chip_info;
 	struct mutex		lock;
 	/*
 	 * triggered buffer
@@ -459,10 +474,18 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
+static const struct hx711_chip_info hx711_chip = {
+	.name		= "hx711",
+	.channels	= hx711_chan_spec,
+	.iio_info	= &hx711_iio_info,
+	.num_channels	= ARRAY_SIZE(hx711_chan_spec),
+};
+
 static int hx711_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct hx711_data *hx711_data;
+	const struct hx711_chip_info *chip_info;
 	struct iio_dev *indio_dev;
 	int ret;
 	int i;
@@ -476,6 +499,11 @@ static int hx711_probe(struct platform_device *pdev)
 
 	mutex_init(&hx711_data->lock);
 
+	chip_info = device_get_match_data(dev);
+	if (!chip_info)
+		return dev_err_probe(dev, -ENODEV, "missing match data\n");
+	hx711_data->chip_info = chip_info;
+
 	/*
 	 * PD_SCK stands for power down and serial clock input of HX711
 	 * in the driver it is an output
@@ -537,11 +565,11 @@ static int hx711_probe(struct platform_device *pdev)
 	hx711_data->data_ready_delay_ns =
 				1000000000 / hx711_data->clock_frequency;
 
-	indio_dev->name = "hx711";
-	indio_dev->info = &hx711_iio_info;
+	indio_dev->name = chip_info->name;
+	indio_dev->info = chip_info->iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = hx711_chan_spec;
-	indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
+	indio_dev->channels = chip_info->channels;
+	indio_dev->num_channels = chip_info->num_channels;
 
 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 					      iio_pollfunc_store_time,
@@ -558,7 +586,7 @@ static int hx711_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id of_hx711_match[] = {
-	{ .compatible = "avia,hx711", },
+	{ .compatible = "avia,hx711", .data = &hx711_chip },
 	{ }
 };
 
-- 
2.43.0