Trickle charging for rtc-bq32k

[Pavel Machek]

Hi!

Here's a patch to enable trickle charging; without it the clock stops
when power is removed -> not very useful.

_But_ this should probably be enabled using device tree entry, right?
Unfortunately, the driver is i2c driver, not platform one, so I don't
see how to do that easily...

Or would module parameter be acceptable?

Thanks,
                                                                Pavel

commit 00abeaa1197a5ad6400497558891793b6cd880d5
Author: Pavel <pa...@ucw.cz>
Date:   Fri Aug 22 14:58:00 2014 +0200

Enable trickle charging for bq32k.

diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c
index c74bf0d..b6a4dd0 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 <pa...@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;
@@ -153,6 +161,25 @@ static int bq32k_probe(struct i2c_client *client,
        if (error)
                return error;
 
+       if (0) {
+               /*
+                * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
+                * over diode and 940ohm resistor)
+                */
+
+               reg = 0x05;
+               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");
+       }
+
        rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
                                                &bq32k_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc))

-- 
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(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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