1 files changed, 29 insertions, 3 deletions

diff --git a/drivers/nfc/s3fwrn5/i2c.c b/drivers/nfc/s3fwrn5/i2c.c
index 897394167522..4d1cf1bb55b0 100644
--- a/drivers/nfc/s3fwrn5/i2c.c
+++ b/drivers/nfc/s3fwrn5/i2c.c
@@ -6,6 +6,7 @@
  * Robert Baldyga <r.baldyga@samsung.com>
  */
 
+#include <linux/clk.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
 #include <linux/delay.h>
@@ -22,6 +23,7 @@
 struct s3fwrn5_i2c_phy {
 	struct phy_common common;
 	struct i2c_client *i2c_dev;
+	struct clk *clk;
 
 	unsigned int irq_skip:1;
 };
@@ -207,17 +209,40 @@ static int s3fwrn5_i2c_probe(struct i2c_client *client,
 	if (ret < 0)
 		return ret;
 
+	phy->clk = devm_clk_get_optional(&client->dev, NULL);
+	if (IS_ERR(phy->clk))
+		return dev_err_probe(&client->dev, PTR_ERR(phy->clk),
+				     "failed to get clock\n");
+
+	/*
+	 * S3FWRN5 depends on a clock input ("XI" pin) to function properly.
+	 * Depending on the hardware configuration this could be an always-on
+	 * oscillator or some external clock that must be explicitly enabled.
+	 * Make sure the clock is running before starting S3FWRN5.
+	 */
+	ret = clk_prepare_enable(phy->clk);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
 	ret = s3fwrn5_probe(&phy->common.ndev, phy, &phy->i2c_dev->dev,
 			    &i2c_phy_ops);
 	if (ret < 0)
-		return ret;
+		goto disable_clk;
 
 	ret = devm_request_threaded_irq(&client->dev, phy->i2c_dev->irq, NULL,
 		s3fwrn5_i2c_irq_thread_fn, IRQF_ONESHOT,
 		S3FWRN5_I2C_DRIVER_NAME, phy);
 	if (ret)
-		s3fwrn5_remove(phy->common.ndev);
+		goto s3fwrn5_remove;
 
+	return 0;
+
+s3fwrn5_remove:
+	s3fwrn5_remove(phy->common.ndev);
+disable_clk:
+	clk_disable_unprepare(phy->clk);
 	return ret;
 }
 
@@ -226,6 +251,7 @@ static int s3fwrn5_i2c_remove(struct i2c_client *client)
 	struct s3fwrn5_i2c_phy *phy = i2c_get_clientdata(client);
 
 	s3fwrn5_remove(phy->common.ndev);
+	clk_disable_unprepare(phy->clk);
 
 	return 0;
 }
@@ -236,7 +262,7 @@ static const struct i2c_device_id s3fwrn5_i2c_id_table[] = {
 };
 MODULE_DEVICE_TABLE(i2c, s3fwrn5_i2c_id_table);
 
-static const struct of_device_id of_s3fwrn5_i2c_match[] = {
+static const struct of_device_id of_s3fwrn5_i2c_match[] __maybe_unused = {
 	{ .compatible = "samsung,s3fwrn5-i2c", },
 	{}
 };