iio: at91_adc: remove usage of iio_priv_to_dev() helper

We may want to get rid of the iio_priv_to_dev() helper. The reason is that
we will hide some of the members of the iio_dev structure (to prevent
drivers from accessing them directly), and that will also mean hiding the
implementation of the iio_priv_to_dev() helper inside the IIO core.

Hiding the implementation of iio_priv_to_dev() implies that some fast-paths
may not be fast anymore, so a general idea is to try to get rid of the
iio_priv_to_dev() altogether.
The iio_priv() helper won't be affected by the rework, as the iio_dev
struct will keep a reference to the private information.

For this driver, not using iio_priv_to_dev(), means reworking some paths to
pass the iio device and using iio_priv() to access the private information.

Signed-off-by: Alexandru Ardelean <[e-mail]>
Tested-by: Eugen Hristev <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/at91_adc.c

···
 	}
 }
 
-static int at91_ts_sample(struct at91_adc_state *st)
+static int at91_ts_sample(struct iio_dev *idev)
 {
+	struct at91_adc_state *st = iio_priv(idev);
 	unsigned int xscale, yscale, reg, z1, z2;
 	unsigned int x, y, pres, xpos, ypos;
 	unsigned int rxp = 1;
 	unsigned int factor = 1000;
-	struct iio_dev *idev = iio_priv_to_dev(st);
 
 	unsigned int xyz_mask_bits = st->res;
 	unsigned int xyz_mask = (1 << xyz_mask_bits) - 1;
···
 
 		if (status & AT91_ADC_ISR_PENS) {
 			/* validate data by pen contact */
-			at91_ts_sample(st);
+			at91_ts_sample(idev);
 		} else {
 			/* triggered by event that is no pen contact, just read
 			 * them to clean the interrupt and discard all.
···
 	return -EINVAL;
 }
 
-static int at91_adc_of_get_resolution(struct at91_adc_state *st,
+static int at91_adc_of_get_resolution(struct iio_dev *idev,
 				      struct platform_device *pdev)
 {
-	struct iio_dev *idev = iio_priv_to_dev(st);
+	struct at91_adc_state *st = iio_priv(idev);
 	struct device_node *np = pdev->dev.of_node;
 	int count, i, ret = 0;
 	char *res_name, *s;
···
 	}
 }
 
-static int at91_adc_probe_dt(struct at91_adc_state *st,
+static int at91_adc_probe_dt(struct iio_dev *idev,
 			     struct platform_device *pdev)
 {
-	struct iio_dev *idev = iio_priv_to_dev(st);
+	struct at91_adc_state *st = iio_priv(idev);
 	struct device_node *node = pdev->dev.of_node;
 	struct device_node *trig_node;
 	int i = 0, ret;
···
 	}
 	st->vref_mv = prop;
 
-	ret = at91_adc_of_get_resolution(st, pdev);
+	ret = at91_adc_of_get_resolution(idev, pdev);
 	if (ret)
 		goto error_ret;
 
···
 		at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_PEN);
 }
 
-static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
+static int at91_ts_hw_init(struct iio_dev *idev, u32 adc_clk_khz)
 {
-	struct iio_dev *idev = iio_priv_to_dev(st);
+	struct at91_adc_state *st = iio_priv(idev);
 	u32 reg = 0;
 	u32 tssctim = 0;
 	int i = 0;
···
 	return 0;
 }
 
-static int at91_ts_register(struct at91_adc_state *st,
+static int at91_ts_register(struct iio_dev *idev,
 		struct platform_device *pdev)
 {
+	struct at91_adc_state *st = iio_priv(idev);
 	struct input_dev *input;
-	struct iio_dev *idev = iio_priv_to_dev(st);
 	int ret;
 
 	input = input_allocate_device();
···
 	st = iio_priv(idev);
 
 	if (pdev->dev.of_node)
-		ret = at91_adc_probe_dt(st, pdev);
+		ret = at91_adc_probe_dt(idev, pdev);
 	else
 		ret = at91_adc_probe_pdata(st, pdev);
 
···
 			goto error_disable_adc_clk;
 		}
 	} else {
-		ret = at91_ts_register(st, pdev);
+		ret = at91_ts_register(idev, pdev);
 		if (ret)
 			goto error_disable_adc_clk;
 
-		at91_ts_hw_init(st, adc_clk_khz);
+		at91_ts_hw_init(idev, adc_clk_khz);
 	}
 
 	ret = iio_device_register(idev);