[PATCH v3 2/9] clk: si5341: Wait for DEVICE_READY on startup
From: Robert Hancock <hidden>
Date: 2021-03-25 19:28:52
Also in:
linux-clk
Subsystem:
common clk framework, the rest · Maintainers:
Michael Turquette, Stephen Boyd, Linus Torvalds
The Si5341 datasheet warns that before accessing any other registers,
including the PAGE register, we need to wait for the DEVICE_READY register
to indicate the device is ready, or the process of the device loading its
state from NVM can be corrupted. Wait for DEVICE_READY on startup before
continuing initialization. This is done using a raw I2C register read
prior to setting up regmap to avoid any potential unwanted automatic PAGE
register accesses from regmap at this stage.
Fixes: 3044a860fd ("clk: Add Si5341/Si5340 driver")
Signed-off-by: Robert Hancock <redacted>
---
drivers/clk/clk-si5341.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c
index e0446e66fa64..b8a960e927bc 100644
--- 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)) {
--
2.27.0