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clk: si5341: Wait for DEVICE_READY on startup

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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>
This commit is contained in:
Robert Hancock 2021-03-25 13:26:36 -06:00 committed by Stephen Boyd
parent c832bb98d3
commit 6e7d2de1e0
1 changed files with 32 additions and 0 deletions
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32
drivers/clk/clk-si5341.c
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@ -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)) {