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>
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c
index c74bf0d..314129e 100644
--- a/drivers/rtc/rtc-bq32k.c
+++ b/drivers/rtc/rtc-bq32k.c
@@ -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 @@
.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, ®, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ reg = 0x20;
+ error = bq32k_write(dev, ®, 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 @@
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))