[PATCH 4/9] clk: si5341: Check for input clock presence and PLL lock on startup

[Robert Hancock <robert.hancock@calian.com>]

After initializing the device, allow sufficient time for the PLL to lock
(if we reconfigured it) and verify that the input clock is present and the
PLL has locked before declaring success.

Fixes: 3044a860fd ("clk: Add Si5341/Si5340 driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/clk/clk-si5341.c | 46 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c
index 2d69b2144acf..5221e431f6cb 100644
--- a/drivers/clk/clk-si5341.c
+++ b/drivers/clk/clk-si5341.c
@@ -92,6 +92,9 @@ struct clk_si5341_output_config {
 #define SI5341_PN_BASE		0x0002
 #define SI5341_DEVICE_REV	0x0005
 #define SI5341_STATUS		0x000C
+#define SI5341_LOS		0x000D
+#define SI5341_STATUS_STICKY	0x0011
+#define SI5341_LOS_STICKY	0x0012
 #define SI5341_SOFT_RST		0x001C
 #define SI5341_IN_SEL		0x0021
 #define SI5341_DEVICE_READY	0x00FE
@@ -99,6 +102,12 @@ struct clk_si5341_output_config {
 #define SI5341_IN_EN		0x0949
 #define SI5341_INX_TO_PFD_EN	0x094A
 
+/* Status bits */
+#define SI5341_STATUS_SYSINCAL	BIT(0)
+#define SI5341_STATUS_LOSXAXB	BIT(1)
+#define SI5341_STATUS_LOSREF	BIT(2)
+#define SI5341_STATUS_LOL	BIT(3)
+
 /* Input selection */
 #define SI5341_IN_SEL_MASK	0x06
 #define SI5341_IN_SEL_SHIFT	1
@@ -1403,6 +1412,29 @@ static int si5341_clk_select_active_input(struct clk_si5341 *data)
 	return res;
 }
 
+static int si5341_check_healthy(struct clk_si5341 *data)
+{
+	u32 status;
+	int res = regmap_read(data->regmap, SI5341_STATUS, &status);
+
+	if (res < 0) {
+		dev_err(&data->i2c_client->dev, "failed to read status\n");
+		return res;
+	}
+
+	if ((status & SI5341_STATUS_LOSREF)) {
+		dev_err(&data->i2c_client->dev, "input clock not present\n");
+		return -EIO;
+	}
+
+	if ((status & SI5341_STATUS_LOL)) {
+		dev_err(&data->i2c_client->dev, "PLL not locked\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
 static int si5341_probe(struct i2c_client *client,
 		const struct i2c_device_id *id)
 {
@@ -1580,6 +1612,20 @@ static int si5341_probe(struct i2c_client *client,
 		err = si5341_finalize_defaults(data);
 		if (err < 0)
 			return err;
+
+		/* allow time for PLL to lock */
+		msleep(250);
+	}
+
+	err = si5341_check_healthy(data);
+	if (err)
+		return err;
+
+	/* clear sticky alarm bits from initialization */
+	err = regmap_write(data->regmap, SI5341_STATUS_STICKY, 0);
+	if (err) {
+		dev_err(&client->dev, "unable to clear sticky status\n");
+		return err;
 	}
 
 	/* Free the names, clk framework makes copies */
-- 
2.27.0