On m41txx you can enable open-drain OUT pin to check if offset is ok.
Enabling OUT pin with frequency_test_enable attribute, OUT pin will tick
512 times faster than 1s tick base.
Enable or Disable FT bit on CONTROL register if freq_test is 1 or 0.
Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-ds1307.c | 96 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 96 insertions(+)
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 2797d01bfa1d..b2e87845d860 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -1053,6 +1053,96 @@ static int m41txx_rtc_set_offset(struct device *dev, long offset)
ctrl_reg);
}
+static ssize_t frequency_test_enable_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ds1307 *ds1307 = dev_get_drvdata(dev);
+ bool freq_test_en = 0;
+ int ret;
+
+ ret = kstrtobool(buf, &freq_test_en);
+ if (ret == -EINVAL) {
+ dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
+ return ret;
+ }
+
+ regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
+ freq_test_en ? M41TXX_BIT_FT : 0);
+
+ return count;
+}
+
+static ssize_t frequency_test_enable_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct ds1307 *ds1307 = dev_get_drvdata(dev);
+ unsigned int ctrl_reg;
+
+ regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
+
+ if (ctrl_reg & M41TXX_BIT_FT)
+ return scnprintf(buf, PAGE_SIZE, "on\n");
+ else
+ return scnprintf(buf, PAGE_SIZE, "off\n");
+}
+
+static DEVICE_ATTR_RW(frequency_test_enable);
+
+static struct attribute *rtc_freq_test_attrs[] = {
+ &dev_attr_frequency_test_enable.attr,
+ NULL,
+};
+
+static const struct attribute_group rtc_freq_test_attr_group = {
+ .attrs = rtc_freq_test_attrs,
+};
+
+static void rtc_calib_remove_sysfs_group(void *_dev)
+{
+ struct device *dev = _dev;
+
+ sysfs_remove_group(&dev->kobj, &rtc_freq_test_attr_group);
+}
+
+static int ds1307_add_frequency_test(struct ds1307 *ds1307)
+{
+ int err = 0;
+
+ switch (ds1307->type) {
+ case m41t0:
+ case m41t00:
+ case m41t11:
+ /* Export sysfs entries */
+ err = sysfs_create_group(&(ds1307->dev)->kobj,
+ &rtc_freq_test_attr_group);
+ if (err) {
+ dev_err(ds1307->dev,
+ "Failed to create sysfs group: %d\n",
+ err);
+ return err;
+ }
+
+ err = devm_add_action_or_reset(ds1307->dev,
+ rtc_calib_remove_sysfs_group,
+ ds1307->dev);
+ if (err) {
+ dev_err(ds1307->dev,
+ "Failed to add sysfs cleanup action: %d\n",
+ err);
+ sysfs_remove_group(&(ds1307->dev)->kobj,
+ &rtc_freq_test_attr_group);
+ return err;
+ }
+ break;
+ default:
+ break;
+ }
+
+ return err;
+}
+
/*----------------------------------------------------------------------*/
static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
@@ -1794,6 +1884,12 @@ static int ds1307_probe(struct i2c_client *client,
if (err)
return err;
+ err = ds1307_add_frequency_test(ds1307);
+ if (err) {
+ rtc_device_unregister(ds1307->rtc);
+ return err;
+ }
+
if (chip->nvram_size) {
struct nvmem_config nvmem_cfg = {
.name = "ds1307_nvram",
--
2.17.0
--
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