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Commit 59a8383a authored by Mylène Josserand's avatar Mylène Josserand Committed by Alexandre Belloni
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rtc: abx80x: handle autocalibration 



The autocalibration is separated in two bits to set in Oscillator
Control register (0x1c) :
 - OSEL bit to select the oscillator type (XT or RC).
 - ACAL bit to select the autocalibration type.

These functionnalities are exported in sysfs entries : "oscillator"
and "autocalibration". Respectively, the values are "xtal" for XT
oscillator and "rc" for RC oscillator and 0 to disable the
autocalibration cycle, 512 for a 512 seconds autocalibration cycle
and 1024 for a cycle of 1024 seconds.

Examples :
Set to XT Oscillator
echo xtal > /sys/class/rtc/rtc0/device/oscillator
Activate an autocalibration every 512 seconds
echo 512 > /sys/class/rtc/rtc0/device/autocalibration

Signed-off-by: default avatarMylène Josserand <mylene.josserand@free-electrons.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 85062c9b

drivers/rtc/rtc-abx80x.c

+219 −0
Original line number Diff line number Diff line
@@ -49,7 +49,19 @@ 


#define ABX8XX_REG_CD_TIMER_CTL	0x18



#define ABX8XX_REG_OSC		0x1c

#define ABX8XX_OSC_FOS		BIT(3)

#define ABX8XX_OSC_BOS		BIT(4)

#define ABX8XX_OSC_ACAL_512	BIT(5)

#define ABX8XX_OSC_ACAL_1024	BIT(6)



#define ABX8XX_OSC_OSEL		BIT(7)



#define ABX8XX_REG_OSS		0x1d

#define ABX8XX_OSS_OMODE	BIT(4)



#define ABX8XX_REG_CFG_KEY	0x1f

#define ABX8XX_CFG_KEY_OSC	0xa1

#define ABX8XX_CFG_KEY_MISC	0x9d



#define ABX8XX_REG_ID0		0x28
@@ -81,6 +93,20 @@ static struct abx80x_cap abx80x_caps[] = { 
	[ABX80X] = {.pn = 0}

};



static int abx80x_is_rc_mode(struct i2c_client *client)

{

	int flags = 0;



	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);

	if (flags < 0) {

		dev_err(&client->dev,

			"Failed to read autocalibration attribute\n");

		return flags;

	}



	return (flags & ABX8XX_OSS_OMODE) ? 1 : 0;

}



static int abx80x_enable_trickle_charger(struct i2c_client *client,

					 u8 trickle_cfg)

{
@@ -248,6 +274,174 @@ static int abx80x_set_alarm(struct device *dev, struct rtc_wkalrm *t) 
	return 0;

}



static int abx80x_rtc_set_autocalibration(struct device *dev,

					  int autocalibration)

{

	struct i2c_client *client = to_i2c_client(dev);

	int retval, flags = 0;



	if ((autocalibration != 0) && (autocalibration != 1024) &&

	    (autocalibration != 512)) {

		dev_err(dev, "autocalibration value outside permitted range\n");

		return -EINVAL;

	}



	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);

	if (flags < 0)

		return flags;



	if (autocalibration == 0) {

		flags &= ~(ABX8XX_OSC_ACAL_512 | ABX8XX_OSC_ACAL_1024);

	} else if (autocalibration == 1024) {

		/* 1024 autocalibration is 0x10 */

		flags |= ABX8XX_OSC_ACAL_1024;

		flags &= ~(ABX8XX_OSC_ACAL_512);

	} else {

		/* 512 autocalibration is 0x11 */

		flags |= (ABX8XX_OSC_ACAL_1024 | ABX8XX_OSC_ACAL_512);

	}



	/* Unlock write access to Oscillator Control Register */

	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,

					   ABX8XX_CFG_KEY_OSC);

	if (retval < 0) {

		dev_err(dev, "Failed to write CONFIG_KEY register\n");

		return retval;

	}



	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);



	return retval;

}



static int abx80x_rtc_get_autocalibration(struct device *dev)

{

	struct i2c_client *client = to_i2c_client(dev);

	int flags = 0, autocalibration;



	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);

	if (flags < 0)

		return flags;



	if (flags & ABX8XX_OSC_ACAL_512)

		autocalibration = 512;

	else if (flags & ABX8XX_OSC_ACAL_1024)

		autocalibration = 1024;

	else

		autocalibration = 0;



	return autocalibration;

}



static ssize_t autocalibration_store(struct device *dev,

				     struct device_attribute *attr,

				     const char *buf, size_t count)

{

	int retval;

	unsigned long autocalibration = 0;



	retval = kstrtoul(buf, 10, &autocalibration);

	if (retval < 0) {

		dev_err(dev, "Failed to store RTC autocalibration attribute\n");

		return -EINVAL;

	}



	retval = abx80x_rtc_set_autocalibration(dev, autocalibration);



	return retval ? retval : count;

}



static ssize_t autocalibration_show(struct device *dev,

				    struct device_attribute *attr, char *buf)

{

	int autocalibration = 0;



	autocalibration = abx80x_rtc_get_autocalibration(dev);

	if (autocalibration < 0) {

		dev_err(dev, "Failed to read RTC autocalibration\n");

		sprintf(buf, "0\n");

		return autocalibration;

	}



	return sprintf(buf, "%d\n", autocalibration);

}



static DEVICE_ATTR_RW(autocalibration);



static ssize_t oscillator_store(struct device *dev,

				struct device_attribute *attr,

				const char *buf, size_t count)

{

	struct i2c_client *client = to_i2c_client(dev);

	int retval, flags, rc_mode = 0;



	if (strncmp(buf, "rc", 2) == 0) {

		rc_mode = 1;

	} else if (strncmp(buf, "xtal", 4) == 0) {

		rc_mode = 0;

	} else {

		dev_err(dev, "Oscillator selection value outside permitted ones\n");

		return -EINVAL;

	}



	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);

	if (flags < 0)

		return flags;



	if (rc_mode == 0)

		flags &= ~(ABX8XX_OSC_OSEL);

	else

		flags |= (ABX8XX_OSC_OSEL);



	/* Unlock write access on Oscillator Control register */

	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,

					   ABX8XX_CFG_KEY_OSC);

	if (retval < 0) {

		dev_err(dev, "Failed to write CONFIG_KEY register\n");

		return retval;

	}



	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);

	if (retval < 0) {

		dev_err(dev, "Failed to write Oscillator Control register\n");

		return retval;

	}



	return retval ? retval : count;

}



static ssize_t oscillator_show(struct device *dev,

			       struct device_attribute *attr, char *buf)

{

	int rc_mode = 0;

	struct i2c_client *client = to_i2c_client(dev);



	rc_mode = abx80x_is_rc_mode(client);



	if (rc_mode < 0) {

		dev_err(dev, "Failed to read RTC oscillator selection\n");

		sprintf(buf, "\n");

		return rc_mode;

	}



	if (rc_mode)

		return sprintf(buf, "rc\n");

	else

		return sprintf(buf, "xtal\n");

}



static DEVICE_ATTR_RW(oscillator);



static struct attribute *rtc_calib_attrs[] = {

	&dev_attr_autocalibration.attr,

	&dev_attr_oscillator.attr,

	NULL,

};



static const struct attribute_group rtc_calib_attr_group = {

	.attrs		= rtc_calib_attrs,

};



static int abx80x_alarm_irq_enable(struct device *dev, unsigned int enabled)

{

	struct i2c_client *client = to_i2c_client(dev);
@@ -303,6 +497,13 @@ static int abx80x_dt_trickle_cfg(struct device_node *np) 
	return (trickle_cfg | i);

}



static void rtc_calib_remove_sysfs_group(void *_dev)

{

	struct device *dev = _dev;



	sysfs_remove_group(&dev->kobj, &rtc_calib_attr_group);

}



static int abx80x_probe(struct i2c_client *client,

			const struct i2c_device_id *id)

{
@@ -405,6 +606,24 @@ static int abx80x_probe(struct i2c_client *client, 
		}

	}



	/* Export sysfs entries */

	err = sysfs_create_group(&(&client->dev)->kobj, &rtc_calib_attr_group);

	if (err) {

		dev_err(&client->dev, "Failed to create sysfs group: %d\n",

			err);

		return err;

	}



	err = devm_add_action(&client->dev, rtc_calib_remove_sysfs_group,

			      &client->dev);

	if (err) {

		rtc_calib_remove_sysfs_group(&client->dev);

		dev_err(&client->dev,

			"Failed to add sysfs cleanup action: %d\n",

			err);

		return err;

	}



	return 0;

}