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Commit 765a98a6 authored by Pavel Machek's avatar Pavel Machek Committed by Linus Torvalds
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rtc: bq32000: add trickle charger option, with device tree binding 



BQ32000 devices have "trickle chargers".  Introduce a code to enable the
charger, based on device tree.

Without charger, RTC does not keep time after power off.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarPavel Machek <pavel@denx.de>
Cc: Jason Cooper <jason@lakedameon.net>
Cc: Matti Vaittinen <matti.vaittinen@nsn.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 33b04b7b

drivers/rtc/rtc-bq32k.c

+62 −0
Original line number Diff line number Diff line
@@ -2,10 +2,14 @@ 
 * Driver for TI BQ32000 RTC.

 *

 * Copyright (C) 2009 Semihalf.

 * Copyright (C) 2014 Pavel Machek <pavel@denx.de>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * You can get hardware description at

 * http://www.ti.com/lit/ds/symlink/bq32000.pdf

 */



#include <linux/module.h>
@@ -27,6 +31,10 @@ 
#define BQ32K_CENT		0x40	/* Century flag */

#define BQ32K_CENT_EN		0x80	/* Century flag enable bit */



#define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */

#define BQ32K_TCH2		0x08	/* Trickle charge enable */

#define BQ32K_CFG2		0x09	/* Trickle charger control */



struct bq32k_regs {

	uint8_t		seconds;

	uint8_t		minutes;
@@ -122,6 +130,57 @@ static const struct rtc_class_ops bq32k_rtc_ops = { 
	.set_time	= bq32k_rtc_set_time,

};



static int trickle_charger_of_init(struct device *dev, struct device_node *node)

{

	unsigned char reg;

	int error;

	u32 ohms = 0;



	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))

		return 0;



	switch (ohms) {

	case 180+940:

		/*

		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging

		 * over diode and 940ohm resistor)

		 */



		if (of_property_read_bool(node, "trickle-diode-disable")) {

			dev_err(dev, "diode and resistor mismatch\n");

			return -EINVAL;

		}

		reg = 0x05;

		break;



	case 180+20000:

		/* diode disabled */



		if (!of_property_read_bool(node, "trickle-diode-disable")) {

			dev_err(dev, "bq32k: diode and resistor mismatch\n");

			return -EINVAL;

		}

		reg = 0x25;

		break;



	default:

		dev_err(dev, "invalid resistor value (%d)\n", ohms);

		return -EINVAL;

	}



	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);

	if (error)

		return error;



	reg = 0x20;

	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);

	if (error)

		return error;



	dev_info(dev, "Enabled trickle RTC battery charge.\n");

	return 0;

}



static int bq32k_probe(struct i2c_client *client,

				const struct i2c_device_id *id)

{
@@ -153,6 +212,9 @@ static int bq32k_probe(struct i2c_client *client, 
	if (error)

		return error;



	if (client && client->dev.of_node)

		trickle_charger_of_init(dev, client->dev.of_node);



	rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,

						&bq32k_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc))