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authorEnric Balletbo i Serra <enric.balletbo@collabora.com>2017-01-27 18:43:46 +0100
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2017-02-01 12:44:23 +0100
commit4c466872d8ae8e3cdc3e5e1a47e28a15e3020d8b (patch)
tree12e1940455bb76c712476e5ef2e66244c09b68f0 /drivers/rtc
parent5dff3a3113173a0c835abbda0eef3c0a2a56cc3a (diff)
downloadlinux-4c466872d8ae8e3cdc3e5e1a47e28a15e3020d8b.tar.bz2
rtc: bq32000: add support to enable disable the trickle charge FET bypass
The bq32000 includes a trickle charge circuit to maintain the charge of the backup supply when a super capacitor is used. You can enable the charging circuit by setting 'trickle-resistor-ohms', additionally you can set TCFE to 1 to bypass the internal diode and boost the charge voltage of the backup supply. You might want to enable/disable the TCFE switch from userspace (e.g when device is only connected to a battery) This patch introduces a new sysfs entry to enable and disable this FET form userspace. Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-bq32k.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c
index 397742446007..2b223935001f 100644
--- a/drivers/rtc/rtc-bq32k.c
+++ b/drivers/rtc/rtc-bq32k.c
@@ -34,6 +34,7 @@
#define BQ32K_CALIBRATION 0x07 /* CAL_CFG1, calibration and control */
#define BQ32K_TCH2 0x08 /* Trickle charge enable */
#define BQ32K_CFG2 0x09 /* Trickle charger control */
+#define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */
struct bq32k_regs {
uint8_t seconds;
@@ -188,6 +189,65 @@ static int trickle_charger_of_init(struct device *dev, struct device_node *node)
return 0;
}
+static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int reg, error;
+
+ error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
+}
+
+static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int reg, enable, error;
+
+ if (kstrtoint(buf, 0, &enable))
+ return -EINVAL;
+
+ error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ if (enable) {
+ reg |= BQ32K_TCFE;
+ error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ dev_info(dev, "Enabled trickle charge FET bypass.\n");
+ } else {
+ reg &= ~BQ32K_TCFE;
+ error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ dev_info(dev, "Disabled trickle charge FET bypass.\n");
+ }
+
+ return count;
+}
+
+static DEVICE_ATTR(trickle_charge_bypass, 0644,
+ bq32k_sysfs_show_tricklecharge_bypass,
+ bq32k_sysfs_store_tricklecharge_bypass);
+
+static int bq32k_sysfs_register(struct device *dev)
+{
+ return device_create_file(dev, &dev_attr_trickle_charge_bypass);
+}
+
+static void bq32k_sysfs_unregister(struct device *dev)
+{
+ device_remove_file(dev, &dev_attr_trickle_charge_bypass);
+}
+
static int bq32k_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
@@ -224,11 +284,26 @@ static int bq32k_probe(struct i2c_client *client,
if (IS_ERR(rtc))
return PTR_ERR(rtc);
+ error = bq32k_sysfs_register(&client->dev);
+ if (error) {
+ dev_err(&client->dev,
+ "Unable to create sysfs entries for rtc bq32000\n");
+ return error;
+ }
+
+
i2c_set_clientdata(client, rtc);
return 0;
}
+static int bq32k_remove(struct i2c_client *client)
+{
+ bq32k_sysfs_unregister(&client->dev);
+
+ return 0;
+}
+
static const struct i2c_device_id bq32k_id[] = {
{ "bq32000", 0 },
{ }
@@ -240,6 +315,7 @@ static struct i2c_driver bq32k_driver = {
.name = "bq32k",
},
.probe = bq32k_probe,
+ .remove = bq32k_remove,
.id_table = bq32k_id,
};