diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 934437bda97b..1a9a8d6f1943 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -18,6 +18,7 @@
 #include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>
+#include <linux/units.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/adc/ad_sigma_delta.h>
@@ -44,6 +45,11 @@
 #define AD7124_STATUS_POR_FLAG			BIT(4)
 
 /* AD7124_ADC_CONTROL */
+#define AD7124_ADC_CONTROL_CLK_SEL		GENMASK(1, 0)
+#define AD7124_ADC_CONTROL_CLK_SEL_INT			0
+#define AD7124_ADC_CONTROL_CLK_SEL_INT_OUT		1
+#define AD7124_ADC_CONTROL_CLK_SEL_EXT			2
+#define AD7124_ADC_CONTROL_CLK_SEL_EXT_DIV4		3
 #define AD7124_ADC_CONTROL_MODE			GENMASK(5, 2)
 #define AD7124_ADC_CONTROL_MODE_CONTINUOUS		0
 #define AD7124_ADC_CONTROL_MODE_SINGLE			1
@@ -92,6 +98,8 @@
 #define AD7124_MAX_CONFIGS	8
 #define AD7124_MAX_CHANNELS	16
 
+#define AD7124_INT_CLK_HZ	614400
+
 /* AD7124 input sources */
 
 enum ad7124_ref_sel {
@@ -120,9 +128,9 @@ static const unsigned int ad7124_reg_size[] = {
 };
 
 static const int ad7124_master_clk_freq_hz[3] = {
-	[AD7124_LOW_POWER] = 76800,
-	[AD7124_MID_POWER] = 153600,
-	[AD7124_FULL_POWER] = 614400,
+	[AD7124_LOW_POWER] = AD7124_INT_CLK_HZ / 8,
+	[AD7124_MID_POWER] = AD7124_INT_CLK_HZ / 4,
+	[AD7124_FULL_POWER] = AD7124_INT_CLK_HZ,
 };
 
 static const char * const ad7124_ref_names[] = {
@@ -174,6 +182,7 @@ struct ad7124_state {
 	struct ad_sigma_delta sd;
 	struct ad7124_channel *channels;
 	struct regulator *vref[4];
+	u32 clk_hz;
 	unsigned int adc_control;
 	unsigned int num_channels;
 	struct mutex cfgs_lock; /* lock for configs access */
@@ -249,12 +258,33 @@ static int ad7124_set_mode(struct ad_sigma_delta *sd,
 	return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, st->adc_control);
 }
 
+static u32 ad7124_get_fclk_hz(struct ad7124_state *st)
+{
+	enum ad7124_power_mode power_mode;
+	u32 fclk_hz;
+
+	power_mode = FIELD_GET(AD7124_ADC_CONTROL_POWER_MODE, st->adc_control);
+	fclk_hz = st->clk_hz;
+
+	switch (power_mode) {
+	case AD7124_LOW_POWER:
+		fclk_hz /= 8;
+		break;
+	case AD7124_MID_POWER:
+		fclk_hz /= 4;
+		break;
+	default:
+		break;
+	}
+
+	return fclk_hz;
+}
+
 static void ad7124_set_channel_odr(struct ad7124_state *st, unsigned int channel, unsigned int odr)
 {
 	unsigned int fclk, odr_sel_bits;
 
-	fclk = ad7124_master_clk_freq_hz[FIELD_GET(AD7124_ADC_CONTROL_POWER_MODE,
-						   st->adc_control)];
+	fclk = ad7124_get_fclk_hz(st);
 
 	/*
 	 * FS[10:0] = fCLK / (fADC x 32) where:
@@ -1112,7 +1142,7 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 static int ad7124_setup(struct ad7124_state *st)
 {
 	struct device *dev = &st->sd.spi->dev;
-	unsigned int power_mode;
+	unsigned int power_mode, clk_sel;
 	struct clk *mclk;
 	int i, ret;
 
@@ -1156,9 +1186,48 @@ static int ad7124_setup(struct ad7124_state *st)
 				return dev_err_probe(dev, ret,
 						     "Failed to set mclk rate\n");
 		}
+
+		clk_sel = AD7124_ADC_CONTROL_CLK_SEL_INT;
+		st->clk_hz = AD7124_INT_CLK_HZ;
+	} else {
+		struct clk *clk;
+
+		clk = devm_clk_get_optional_enabled(dev, NULL);
+		if (IS_ERR(clk))
+			return dev_err_probe(dev, PTR_ERR(clk),
+					     "Failed to get external clock\n");
+
+		if (clk) {
+			unsigned long clk_hz;
+
+			clk_hz = clk_get_rate(clk);
+			if (!clk_hz)
+				return dev_err_probe(dev, -EINVAL,
+					"Failed to get external clock rate\n");
+
+			/*
+			 * The external clock may be 4x the nominal clock rate,
+			 * in which case the ADC needs to be configured to
+			 * divide it by 4. Using MEGA is a bit arbitrary, but
+			 * the expected clock rates are either 614.4 kHz or
+			 * 2.4576 MHz, so this should work.
+			 */
+			if (clk_hz > (1 * HZ_PER_MHZ)) {
+				clk_sel = AD7124_ADC_CONTROL_CLK_SEL_EXT_DIV4;
+				st->clk_hz = clk_hz / 4;
+			} else {
+				clk_sel = AD7124_ADC_CONTROL_CLK_SEL_EXT;
+				st->clk_hz = clk_hz;
+			}
+		} else {
+			clk_sel = AD7124_ADC_CONTROL_CLK_SEL_INT;
+			st->clk_hz = AD7124_INT_CLK_HZ;
+		}
 	}
 
-	/* Set the power mode */
+	st->adc_control &= ~AD7124_ADC_CONTROL_CLK_SEL;
+	st->adc_control |= FIELD_PREP(AD7124_ADC_CONTROL_CLK_SEL, clk_sel);
+
 	st->adc_control &= ~AD7124_ADC_CONTROL_POWER_MODE;
 	st->adc_control |= FIELD_PREP(AD7124_ADC_CONTROL_POWER_MODE, power_mode);