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Commit 176f9f29 authored by Grant Grundler's avatar Grant Grundler Committed by Greg Kroah-Hartman
Browse files

STAGING:iio:light: fix ISL29018 init to handle brownout 



After a voltage brownout, sensor will now operate correctly.

Page 10 of ISL29018 data sheet and the Intersil Application Note 1534
describe the required initialization sequence:
1. Write 0x00 to register 0x08 (TEST)
2. Write 0x00 to register 0x00 (CMD1)
3. msleep(1)
4. program remaining registers as before

Signed-off-by: default avatarGrant Grundler <grundler@chromium.org>
Reviewed-by: default avatarBryan Freed <bfreed@chromium.org>
Acked-by: default avatarJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f94aa354

drivers/staging/iio/light/isl29018.c

+46 −0
Original line number Diff line number Diff line
@@ -53,6 +53,10 @@ 
#define ISL29018_REG_ADD_DATA_MSB	0x03

#define ISL29018_MAX_REGS		ISL29018_REG_ADD_DATA_MSB



#define ISL29018_REG_TEST		0x08

#define ISL29018_TEST_SHIFT		0

#define ISL29018_TEST_MASK		(0xFF << ISL29018_TEST_SHIFT)



struct isl29018_chip {

	struct i2c_client	*client;

	struct mutex		lock;
@@ -457,6 +461,48 @@ static int isl29018_chip_init(struct i2c_client *client) 


	memset(chip->reg_cache, 0, sizeof(chip->reg_cache));



	/* Code added per Intersil Application Note 1534:

	 *     When VDD sinks to approximately 1.8V or below, some of

	 * the part's registers may change their state. When VDD

	 * recovers to 2.25V (or greater), the part may thus be in an

	 * unknown mode of operation. The user can return the part to

	 * a known mode of operation either by (a) setting VDD = 0V for

	 * 1 second or more and then powering back up with a slew rate

	 * of 0.5V/ms or greater, or (b) via I2C disable all ALS/PROX

	 * conversions, clear the test registers, and then rewrite all

	 * registers to the desired values.

	 * ...

	 * FOR ISL29011, ISL29018, ISL29021, ISL29023

	 * 1. Write 0x00 to register 0x08 (TEST)

	 * 2. Write 0x00 to register 0x00 (CMD1)

	 * 3. Rewrite all registers to the desired values

	 *

	 * ISL29018 Data Sheet (FN6619.1, Feb 11, 2010) essentially says

	 * the same thing EXCEPT the data sheet asks for a 1ms delay after

	 * writing the CMD1 register.

	 */

	status = isl29018_write_data(client, ISL29018_REG_TEST, 0,

				ISL29018_TEST_MASK, ISL29018_TEST_SHIFT);

	if (status < 0) {

		dev_err(&client->dev, "Failed to clear isl29018 TEST reg."

					"(%d)\n", status);

		return status;

	}



	/* See Intersil AN1534 comments above.

	 * "Operating Mode" (COMMAND1) register is reprogrammed when

	 * data is read from the device.

	 */

	status = isl29018_write_data(client, ISL29018_REG_ADD_COMMAND1, 0,

				0xff, 0);

	if (status < 0) {

		dev_err(&client->dev, "Failed to clear isl29018 CMD1 reg."

					"(%d)\n", status);

		return status;

	}



	msleep(1);	/* per data sheet, page 10 */



	/* set defaults */

	status = isl29018_set_range(client, chip->range, &new_range);

	if (status < 0) {