[PATCH v2 08/19] staging: iio: resolver: ad2s1210: use devicetree to get fclkin

[David Lechner <dlechner@xxxxxxxxxxxx>]

This removes the fclkin sysfs attribute and replaces it with getting
the fclkin clock rate using the clk subsystem (i.e. from the
devicetree).

The fclkin clock comes from an external oscillator that is connected
directly to the AD2S1210 chip, so users of the sysfs attributes should
not need to be concerned with this.

Also sort includes while we are touching this.

Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---
 drivers/staging/iio/resolver/Kconfig    |  1 +
 drivers/staging/iio/resolver/ad2s1210.c | 76 +++++++++----------------
 2 files changed, 28 insertions(+), 49 deletions(-)

diff --git a/drivers/staging/iio/resolver/Kconfig b/drivers/staging/iio/resolver/Kconfig
index 6d1e2622e0b0..bebb35822c9e 100644
--- a/drivers/staging/iio/resolver/Kconfig
+++ b/drivers/staging/iio/resolver/Kconfig
@@ -7,6 +7,7 @@ menu "Resolver to digital converters"
 config AD2S1210
 	tristate "Analog Devices ad2s1210 driver"
 	depends on SPI
+	depends on COMMON_CLK
 	depends on GPIOLIB || COMPILE_TEST
 	help
 	  Say yes here to build support for Analog Devices spi resolver
diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index 95d43b241a75..153ac7704ad7 100644
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -5,16 +5,17 @@
  * Copyright (c) 2010-2010 Analog Devices Inc.
  * Copyright (C) 2023 BayLibre, SAS
  */
-#include <linux/types.h>
-#include <linux/mutex.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
-#include <linux/spi/spi.h>
 #include <linux/slab.h>
+#include <linux/spi/spi.h>
 #include <linux/sysfs.h>
-#include <linux/delay.h>
-#include <linux/gpio/consumer.h>
-#include <linux/module.h>
+#include <linux/types.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -91,7 +92,8 @@ struct ad2s1210_state {
 	struct mutex lock;
 	struct spi_device *sdev;
 	struct gpio_desc *gpios[5];
-	unsigned int fclkin;
+	/** The external oscillator frequency in Hz. */
+	unsigned long fclkin;
 	unsigned int fexcit;
 	bool hysteresis;
 	u8 resolution;
@@ -198,45 +200,6 @@ static inline int ad2s1210_soft_reset(struct ad2s1210_state *st)
 	return ad2s1210_config_write(st, 0x0);
 }
 
-static ssize_t ad2s1210_show_fclkin(struct device *dev,
-				    struct device_attribute *attr,
-				    char *buf)
-{
-	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
-
-	return sprintf(buf, "%u\n", st->fclkin);
-}
-
-static ssize_t ad2s1210_store_fclkin(struct device *dev,
-				     struct device_attribute *attr,
-				     const char *buf,
-				     size_t len)
-{
-	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
-	unsigned int fclkin;
-	int ret;
-
-	ret = kstrtouint(buf, 10, &fclkin);
-	if (ret)
-		return ret;
-	if (fclkin < AD2S1210_MIN_CLKIN || fclkin > AD2S1210_MAX_CLKIN) {
-		dev_err(dev, "ad2s1210: fclkin out of range\n");
-		return -EINVAL;
-	}
-
-	mutex_lock(&st->lock);
-	st->fclkin = fclkin;
-
-	ret = ad2s1210_update_frequency_control_word(st);
-	if (ret < 0)
-		goto error_ret;
-	ret = ad2s1210_soft_reset(st);
-error_ret:
-	mutex_unlock(&st->lock);
-
-	return ret < 0 ? ret : len;
-}
-
 static ssize_t ad2s1210_show_fexcit(struct device *dev,
 				    struct device_attribute *attr,
 				    char *buf)
@@ -546,8 +509,6 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static IIO_DEVICE_ATTR(fclkin, 0644,
-		       ad2s1210_show_fclkin, ad2s1210_store_fclkin, 0);
 static IIO_DEVICE_ATTR(fexcit, 0644,
 		       ad2s1210_show_fexcit,	ad2s1210_store_fexcit, 0);
 static IIO_DEVICE_ATTR(control, 0644,
@@ -596,7 +557,6 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
 };
 
 static struct attribute *ad2s1210_attributes[] = {
-	&iio_dev_attr_fclkin.dev_attr.attr,
 	&iio_dev_attr_fexcit.dev_attr.attr,
 	&iio_dev_attr_control.dev_attr.attr,
 	&iio_dev_attr_bits.dev_attr.attr,
@@ -654,6 +614,24 @@ static const struct iio_info ad2s1210_info = {
 	.attrs = &ad2s1210_attribute_group,
 };
 
+static int ad2s1210_setup_clocks(struct ad2s1210_state *st)
+{
+	struct device *dev = &st->sdev->dev;
+	struct clk *clk;
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
+
+	st->fclkin = clk_get_rate(clk);
+	if (st->fclkin < AD2S1210_MIN_CLKIN || st->fclkin > AD2S1210_MAX_CLKIN)
+		return dev_err_probe(dev, -EINVAL,
+				     "clock frequency out of range: %lu\n",
+				     st->fclkin);
+
+	return 0;
+}
+
 static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
 {
 	struct spi_device *spi = st->sdev;
-- 
2.34.1