clk: si5341: Wait for DEVICE_READY on startup

[linux-2.6-microblaze.git] / drivers / clk / clk-si5341.c

diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c
index e0446e6..b8a960e 100644 (file)
--- a/drivers/clk/clk-si5341.c
+++ b/drivers/clk/clk-si5341.c
@@ -94,6 +94,7 @@ struct clk_si5341_output_config {
 #define SI5341_STATUS          0x000C
 #define SI5341_SOFT_RST                0x001C
 #define SI5341_IN_SEL          0x0021
+#define SI5341_DEVICE_READY    0x00FE
 #define SI5341_XAXB_CFG                0x090E
 #define SI5341_IN_EN           0x0949
 #define SI5341_INX_TO_PFD_EN   0x094A
@@ -1189,6 +1190,32 @@ static const struct regmap_range_cfg si5341_regmap_ranges[] = {
        },
 };
 
+static int si5341_wait_device_ready(struct i2c_client *client)
+{
+       int count;
+
+       /* Datasheet warns: Any attempt to read or write any register other
+        * than DEVICE_READY before DEVICE_READY reads as 0x0F may corrupt the
+        * NVM programming and may corrupt the register contents, as they are
+        * read from NVM. Note that this includes accesses to the PAGE register.
+        * Also: DEVICE_READY is available on every register page, so no page
+        * change is needed to read it.
+        * Do this outside regmap to avoid automatic PAGE register access.
+        * May take up to 300ms to complete.
+        */
+       for (count = 0; count < 15; ++count) {
+               s32 result = i2c_smbus_read_byte_data(client,
+                                                     SI5341_DEVICE_READY);
+               if (result < 0)
+                       return result;
+               if (result == 0x0F)
+                       return 0;
+               msleep(20);
+       }
+       dev_err(&client->dev, "timeout waiting for DEVICE_READY\n");
+       return -EIO;
+}
+
 static const struct regmap_config si5341_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
@@ -1385,6 +1412,11 @@ static int si5341_probe(struct i2c_client *client,
 
        data->i2c_client = client;
 
+       /* Must be done before otherwise touching hardware */
+       err = si5341_wait_device_ready(client);
+       if (err)
+               return err;
+
        for (i = 0; i < SI5341_NUM_INPUTS; ++i) {
                input = devm_clk_get(&client->dev, si5341_input_clock_names[i]);
                if (IS_ERR(input)) {