Commit d9d4944d authored by Saeed Nowshadi's avatar Saeed Nowshadi Committed by Stephen Boyd
Browse files

clk: si570: Skip NVM to RAM recall operation if an optional property is set 



Recalling NVM data into RAM during probe() initiates a re-calibration of
the clock. If the clock is already in-use, the recall operation can cause
a glitch on the frequency out. At power on, the factory data are loaded
from NVM into RAM by default. If the clock frequency has been changed
since power on, the recall operation can be used to re-initialize the clock
to factory setting.

Signed-off-by: default avatarMichal Simek <michal.simek@xilinx.com>
Signed-off-by: default avatarSaeed Nowshadi <saeed.nowshadi@xilinx.com>
Link: https://lore.kernel.org/r/1612496104-3437-3-git-send-email-saeed.nowshadi@xilinx.com


Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent 3dff4bec

drivers/clk/clk-si570.c

+12 −4
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 
 *

 * Copyright (C) 2010, 2011 Ericsson AB.

 * Copyright (C) 2011 Guenter Roeck.

 * Copyright (C) 2011 - 2013 Xilinx Inc.

 * Copyright (C) 2011 - 2021 Xilinx Inc.

 *

 * Author: Guenter Roeck <guenter.roeck@ericsson.com>

 *	   Sören Brinkmann <soren.brinkmann@xilinx.com>
@@ -123,14 +123,18 @@ static int si570_get_divs(struct clk_si570 *data, u64 *rfreq, 
 * si570_get_defaults() - Get default values

 * @data:	Driver data structure

 * @fout:	Factory frequency output

 * @skip_recall:	If true, don't recall NVM into RAM

 * Returns 0 on success, negative errno otherwise.

 */

static int si570_get_defaults(struct clk_si570 *data, u64 fout)

static int si570_get_defaults(struct clk_si570 *data, u64 fout,

			      bool skip_recall)

{

	int err;

	u64 fdco;



	regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_RECALL);

	if (!skip_recall)

		regmap_write(data->regmap, SI570_REG_CONTROL,

			     SI570_CNTRL_RECALL);



	err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div);

	if (err)
@@ -400,6 +404,7 @@ static int si570_probe(struct i2c_client *client, 
	struct clk_si570 *data;

	struct clk_init_data init;

	u32 initial_fout, factory_fout, stability;

	bool skip_recall;

	int err;

	enum clk_si570_variant variant = id->driver_data;
@@ -441,6 +446,9 @@ static int si570_probe(struct i2c_client *client, 
		return err;

	}



	skip_recall = of_property_read_bool(client->dev.of_node,

					    "silabs,skip-recall");



	data->regmap = devm_regmap_init_i2c(client, &si570_regmap_config);

	if (IS_ERR(data->regmap)) {

		dev_err(&client->dev, "failed to allocate register map\n");
@@ -448,7 +456,7 @@ static int si570_probe(struct i2c_client *client, 
	}



	i2c_set_clientdata(client, data);

	err = si570_get_defaults(data, factory_fout);

	err = si570_get_defaults(data, factory_fout, skip_recall);

	if (err)

		return err;