staging: iio: frequency: ad9833: Load clock using clock framework

The clock frequency is loaded from device-tree using clock framework
instead of statically value. The change allow configuration of
the device via device-trees and better initialization sequence.
This is part of broader effort to add device-tree support to this driver
and take it out from staging.
Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/frequency/ad9834.c

@@ -6,6 +6,7 @@
  * Licensed under the GPL-2.
  */
 
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/workqueue.h>
 #include <linux/device.h>
@@ -71,7 +72,7 @@
 struct ad9834_state {
 	struct spi_device		*spi;
 	struct regulator		*reg;
-	unsigned int			mclk;
+	struct clk			*mclk;
 	unsigned short			control;
 	unsigned short			devid;
 	struct spi_transfer		xfer;
@@ -110,12 +111,15 @@ static unsigned int ad9834_calc_freqreg(unsigned long mclk, unsigned long fout)
 static int ad9834_write_frequency(struct ad9834_state *st,
 				  unsigned long addr, unsigned long fout)
 {
+	unsigned long clk_freq;
 	unsigned long regval;
 
-	if (fout > (st->mclk / 2))
+	clk_freq = clk_get_rate(st->mclk);
+
+	if (fout > (clk_freq / 2))
 		return -EINVAL;
 
-	regval = ad9834_calc_freqreg(st->mclk, fout);
+	regval = ad9834_calc_freqreg(clk_freq, fout);
 
 	st->freq_data[0] = cpu_to_be16(addr | (regval &
 				       RES_MASK(AD9834_FREQ_BITS / 2)));
@@ -413,7 +417,14 @@ static int ad9834_probe(struct spi_device *spi)
 	spi_set_drvdata(spi, indio_dev);
 	st = iio_priv(indio_dev);
 	mutex_init(&st->lock);
-	st->mclk = 25000000;
+	st->mclk = devm_clk_get(&spi->dev, NULL);
+
+	ret = clk_prepare_enable(st->mclk);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to enable master clock\n");
+		goto error_disable_reg;
+	}
+
 	st->spi = spi;
 	st->devid = spi_get_device_id(spi)->driver_data;
 	st->reg = reg;
@@ -458,31 +469,32 @@ static int ad9834_probe(struct spi_device *spi)
 	ret = spi_sync(st->spi, &st->msg);
 	if (ret) {
 		dev_err(&spi->dev, "device init failed\n");
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 	}
 
 	ret = ad9834_write_frequency(st, AD9834_REG_FREQ0, 1000000);
 	if (ret)
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 
 	ret = ad9834_write_frequency(st, AD9834_REG_FREQ1, 5000000);
 	if (ret)
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 
 	ret = ad9834_write_phase(st, AD9834_REG_PHASE0, 512);
 	if (ret)
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 
 	ret = ad9834_write_phase(st, AD9834_REG_PHASE1, 1024);
 	if (ret)
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 
 	ret = iio_device_register(indio_dev);
 	if (ret)
-		goto error_disable_reg;
+		goto error_clock_unprepare;
 
 	return 0;
-
+error_clock_unprepare:
+	clk_disable_unprepare(st->mclk);
 error_disable_reg:
 	regulator_disable(reg);
 
@@ -495,6 +507,7 @@ static int ad9834_remove(struct spi_device *spi)
 	struct ad9834_state *st = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
+	clk_disable_unprepare(st->mclk);
 	regulator_disable(st->reg);
 
 	return 0;