iio:ad9361 print out the SPI CLK during probe

This will only work for those SPI controllers which populate their
effective_speed_hz during the clock setting, but for those that do,
this will print out the SPI clock (in MHz) so it is easier to understand
what's going on in the system.

will see things like:
ad9361 : AD936x Rev 2 successfully initialized (SPI @ 5.20 MHz)
or
ad9361 : AD936x Rev 2 successfully initialized (SPI @ 41.66 MHz)
or (with older SPI controller drivers)
ad9361 : AD936x Rev 2 successfully initialized

tested on PlutoSDR

Signed-off-by: Robin Getz <[email protected]>

drivers/iio/adc/ad9361.c

@@ -9399,13 +9399,44 @@ ad9361_gt_bin_read(struct file *filp, struct kobject *kobj,
 	return ret;
 }
 
+static int ad9361_spi_check(struct spi_device *spi)
+{
+	u8 buf[3] = {0};
+	int ret;
+	u16 cmd;
+	struct spi_transfer t = {
+		.tx_buf = buf,
+		.rx_buf = buf,
+		.len = sizeof(buf),
+	};
+
+	/*
+	 * We need do a low level spi transfer to get the effective speed
+	 * otherwise we would just do a ad9361_spi_read()
+	 */
+	cmd = AD_READ | AD_CNT(1) | AD_ADDR(REG_PRODUCT_ID);
+	buf[0] = cmd >> 8;
+	buf[1] = cmd & 0xFF;
+
+	ret = spi_sync_transfer(spi, &t, 1);
+	if (ret)
+		return ret;
+
+	if ((buf[2] & PRODUCT_ID_MASK) != PRODUCT_ID_9361) {
+		dev_err(&spi->dev, "%s : Unsupported PRODUCT_ID 0x%X", __func__, buf[2]);
+		return -ENODEV;
+	}
+
+	return t.effective_speed_hz;
+}
+
 static int ad9361_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
 	struct ad9361_rf_phy_state *st;
 	struct ad9361_rf_phy *phy;
 	struct clk *clk = NULL;
-	int ret, rev;
+	int ret, rev, hz;
 
 	dev_info(&spi->dev, "%s : enter (%s)", __func__,
 		 spi_get_device_id(spi)->name);
@@ -9468,12 +9499,9 @@ static int ad9361_probe(struct spi_device *spi)
 
 	ad9361_reset(phy);
 
-	ret = ad9361_spi_read(spi, REG_PRODUCT_ID);
-	if ((ret & PRODUCT_ID_MASK) != PRODUCT_ID_9361) {
-		dev_err(&spi->dev, "%s : Unsupported PRODUCT_ID 0x%X",
-			__func__, ret);
-		return -ENODEV;
-	}
+	hz = ad9361_spi_check(spi);
+	if (hz < 0)
+		return hz;
 
 	rev = ret & REV_MASK;
 
@@ -9544,8 +9572,12 @@ static int ad9361_probe(struct spi_device *spi)
 	if (ret < 0)
 		dev_warn(&spi->dev, "%s: failed to register debugfs", __func__);
 
-	dev_info(&spi->dev, "%s : AD936x Rev %d successfully initialized",
-		 __func__, rev);
+	if (hz > 0)
+		dev_info(&spi->dev, "%s : AD936x Rev %d successfully initialized (SPI @ %u.%02u MHz)",
+				__func__, rev, hz / 1000000, hz % 1000000 / 1000 / 10);
+	else
+		dev_info(&spi->dev, "%s : AD936x Rev %d successfully initialized",
+				__func__, rev);
 
 	return 0;