From: Enric Balletbo i Serra <enric.balletbo@collabora.com>
To: Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com
Subject: [PATCH] rtc: bq32000: add support to enable disable the trickle charge FET bypass.
Date: Fri, 27 Jan 2017 18:43:46 +0100 [thread overview]
Message-ID: <20170127174346.30131-1-enric.balletbo@collabora.com> (raw)
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>
---
.../ABI/testing/sysfs-bus-i2c-devices-bq32k | 7 ++
drivers/rtc/rtc-bq32k.c | 76 ++++++++++++++++++++++
2 files changed, 83 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-bus-i2c-devices-bq32k
diff --git a/Documentation/ABI/testing/sysfs-bus-i2c-devices-bq32k b/Documentation/ABI/testing/sysfs-bus-i2c-devices-bq32k
new file mode 100644
index 0000000..398b258
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-i2c-devices-bq32k
@@ -0,0 +1,7 @@
+What: /sys/bus/i2c/devices/.../trickle_charge_bypass
+Date: Jan 2017
+KernelVersion: 4.11
+Contact: Enric Balletbo i Serra <eballetbo@gmail.com>
+Description: Attribute for enable/disable the trickle charge bypass
+ The trickle_charge_bypass attribute allows the userspace to
+ enable/disable the Trickle charge FET bypass.
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c
index 3977424..2b22393 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, ®, 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, ®, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ if (enable) {
+ reg |= BQ32K_TCFE;
+ error = bq32k_write(dev, ®, BQ32K_CFG2, 1);
+ if (error)
+ return error;
+
+ dev_info(dev, "Enabled trickle charge FET bypass.\n");
+ } else {
+ reg &= ~BQ32K_TCFE;
+ error = bq32k_write(dev, ®, 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,
};
--
2.9.3
next reply other threads:[~2017-01-27 17:44 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-27 17:43 Enric Balletbo i Serra [this message]
2017-01-31 21:03 ` [PATCH] rtc: bq32000: add support to enable disable the trickle charge FET bypass Alexandre Belloni
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