[PATCH v3 4/9] clk: si5341: Check for input clock presence and PLL lock on startup

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

After initializing the device, wait for it to report 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 | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c
index ac1ccec2b681..da40b90c2aa8 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
@@ -1416,6 +1425,7 @@ static int si5341_probe(struct i2c_client *client,
 	unsigned int i;
 	struct clk_si5341_output_config config[SI5341_MAX_NUM_OUTPUTS];
 	bool initialization_required;
+	u32 status;
 
 	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -1583,6 +1593,22 @@ static int si5341_probe(struct i2c_client *client,
 			return err;
 	}
 
+	/* wait for device to report input clock present and PLL lock */
+	err = regmap_read_poll_timeout(data->regmap, SI5341_STATUS, status,
+		!(status & (SI5341_STATUS_LOSREF | SI5341_STATUS_LOL)),
+	       10000, 250000);
+	if (err) {
+		dev_err(&client->dev, "Error waiting for input clock or PLL lock\n");
+		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 */
 	for (i = 0; i < data->num_synth; ++i)
 		 devm_kfree(&client->dev, (void *)synth_clock_names[i]);
-- 
2.27.0