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| author |   Robert Hancock <robert.hancock@calian.com> | 2021-03-25 13:26:36 -0600 |
|---|---|---|
| committer |   Stephen Boyd <sboyd@kernel.org> | 2021-06-27 19:58:14 -0700 |
| commit | 6e7d2de1e000d36990923ed80d2e78dfcb545cee (patch) | |
| tree | ce46b57cb82ef401c2283258d61c5489f098a69f /drivers/clk/clk-si5341.c | |
| parent | dt-bindings: clock: clk-si5341: Add new attributes (diff) | |
| download | linux-dev-6e7d2de1e000d36990923ed80d2e78dfcb545cee.tar.xz linux-dev-6e7d2de1e000d36990923ed80d2e78dfcb545cee.zip | |
clk: si5341: Wait for DEVICE_READY on startup
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 <robert.hancock@calian.com>
Link: https://lore.kernel.org/r/20210325192643.2190069-3-robert.hancock@calian.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Diffstat (limited to 'drivers/clk/clk-si5341.c')
| -rw-r--r-- | drivers/clk/clk-si5341.c | 32 |
1 files changed, 32 insertions, 0 deletions
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)) { |