Commit 6e7d2de1 authored by Robert Hancock's avatar Robert Hancock Committed by Stephen Boyd
Browse files

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: 3044a860 ("clk: Add Si5341/Si5340 driver")
Signed-off-by: default avatarRobert Hancock <robert.hancock@calian.com>
Link: https://lore.kernel.org/r/20210325192643.2190069-3-robert.hancock@calian.com


Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent c832bb98

drivers/clk/clk-si5341.c

+32 −0
Original line number Diff line number Diff line
@@ -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)) {