staging: iio: ad5933: use clock framework for clock reference

Add the option to specify the external clock (MCLK) using the clock
framework.
Also remove the old platform data structure.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Signed-off-by: Gabriel Capella <gabriel@capella.pro>
Co-developed-by: Gabriel Capella <gabriel@capella.pro>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/impedance-analyzer/ad5933.c

@@ -16,6 +16,7 @@
 #include <linux/err.h>
 #include <linux/delay.h>
 #include <linux/module.h>
+#include <linux/clk.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -82,20 +83,10 @@
 #define AD5933_POLL_TIME_ms		10
 #define AD5933_INIT_EXCITATION_TIME_ms	100
 
-/**
- * struct ad5933_platform_data - platform specific data
- * @ext_clk_hz:		the external clock frequency in Hz, if not set
- *			the driver uses the internal clock (16.776 MHz)
- * @vref_mv:		the external reference voltage in millivolt
- */
-
-struct ad5933_platform_data {
-	unsigned long			ext_clk_hz;
-};
-
 struct ad5933_state {
 	struct i2c_client		*client;
 	struct regulator		*reg;
+	struct clk			*mclk;
 	struct delayed_work		work;
 	struct mutex			lock; /* Protect sensor state */
 	unsigned long			mclk_hz;
@@ -111,9 +102,6 @@ struct ad5933_state {
 	unsigned int			poll_time_jiffies;
 };
 
-static struct ad5933_platform_data ad5933_default_pdata  = {
-};
-
 #define AD5933_CHANNEL(_type, _extend_name, _info_mask_separate, _address, \
 		_scan_index, _realbits) { \
 	.type = (_type), \
@@ -690,9 +678,9 @@ static int ad5933_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	int ret;
-	struct ad5933_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct ad5933_state *st;
 	struct iio_dev *indio_dev;
+	unsigned long ext_clk_hz = 0;
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
 	if (!indio_dev)
@@ -704,9 +692,6 @@ static int ad5933_probe(struct i2c_client *client,
 
 	mutex_init(&st->lock);
 
-	if (!pdata)
-		pdata = &ad5933_default_pdata;
-
 	st->reg = devm_regulator_get(&client->dev, "vdd");
 	if (IS_ERR(st->reg))
 		return PTR_ERR(st->reg);
@@ -723,8 +708,21 @@ static int ad5933_probe(struct i2c_client *client,
 
 	st->vref_mv = ret / 1000;
 
-	if (pdata->ext_clk_hz) {
-		st->mclk_hz = pdata->ext_clk_hz;
+	st->mclk = devm_clk_get(&client->dev, "mclk");
+	if (IS_ERR(st->mclk) && PTR_ERR(st->mclk) != -ENOENT) {
+		ret = PTR_ERR(st->mclk);
+		goto error_disable_reg;
+	}
+
+	if (!IS_ERR(st->mclk)) {
+		ret = clk_prepare_enable(st->mclk);
+		if (ret < 0)
+			goto error_disable_reg;
+		ext_clk_hz = clk_get_rate(st->mclk);
+	}
+
+	if (ext_clk_hz) {
+		st->mclk_hz = ext_clk_hz;
 		st->ctrl_lb = AD5933_CTRL_EXT_SYSCLK;
 	} else {
 		st->mclk_hz = AD5933_INT_OSC_FREQ_Hz;
@@ -744,7 +742,7 @@ static int ad5933_probe(struct i2c_client *client,
 
 	ret = ad5933_register_ring_funcs_and_init(indio_dev);
 	if (ret)
-		goto error_disable_reg;
+		goto error_disable_mclk;
 
 	ret = ad5933_setup(st);
 	if (ret)
@@ -758,6 +756,8 @@ static int ad5933_probe(struct i2c_client *client,
 
 error_unreg_ring:
 	iio_kfifo_free(indio_dev->buffer);
+error_disable_mclk:
+	clk_disable_unprepare(st->mclk);
 error_disable_reg:
 	regulator_disable(st->reg);
 
@@ -772,6 +772,7 @@ static int ad5933_remove(struct i2c_client *client)
 	iio_device_unregister(indio_dev);
 	iio_kfifo_free(indio_dev->buffer);
 	regulator_disable(st->reg);
+	clk_disable_unprepare(st->mclk);
 
 	return 0;
 }