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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: Pavel 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Pavel Machek 2014-10-13 15:52:50 -07:00 committed by Linus Torvalds
parent 33b04b7b7c
commit 765a98a6b9
1 changed files with 62 additions and 0 deletions
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62
drivers/rtc/rtc-bq32k.c
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@ -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))