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Commit f6c61cff authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
Browse files

hwmon: (lm85) Add support for ADT7468 high-frequency PWM mode 



The ADT7468 supports a high-frequency PWM output mode where all PWM
outputs are driven by a 22.5 kHz clock. Add support for this mode, and
document it, as it may surprise the user that setting one PWM output
frequency also affects the other PWM outputs.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Cc: Darrick J. Wong <djwong@us.ibm.com>
Acked-by: default avatarGuenter Roeck <guenter.roeck@ericsson.com>
parent c36364db

Documentation/hwmon/lm85

+7 −0
Original line number Diff line number Diff line
@@ -101,6 +101,13 @@ Devices has confirmed this "bug". The ADT7463 is reported to work as 
described in the documentation. The current lm85 driver does not show the

offset register.



The ADT7468 has a high-frequency PWM mode, where all PWM outputs are

driven by a 22.5 kHz clock. This is a global mode, not per-PWM output,

which means that setting any PWM frequency above 11.3 kHz will switch

all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM

frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency

between 10 and 100 Hz, which can then be tuned separately.



See the vendor datasheets for more information. There is application note

from National (AN-1260) with some additional information about the LM85.

The Analog Devices datasheet is very detailed and describes a procedure for

drivers/hwmon/lm85.c

+28 −7
Original line number Diff line number Diff line
@@ -64,9 +64,12 @@ enum chips { 
#define	LM85_REG_VERSTEP		0x3f



#define	ADT7468_REG_CFG5		0x7c

#define		ADT7468_OFF64		0x01

#define		ADT7468_OFF64		(1 << 0)

#define		ADT7468_HFPWM		(1 << 1)

#define	IS_ADT7468_OFF64(data)		\

	((data)->type == adt7468 && !((data)->cfg5 & ADT7468_OFF64))

#define	IS_ADT7468_HFPWM(data)		\

	((data)->type == adt7468 && !((data)->cfg5 & ADT7468_HFPWM))



/* These are the recognized values for the above regs */

#define	LM85_COMPANY_NATIONAL		0x01
@@ -567,8 +570,14 @@ static ssize_t show_pwm_freq(struct device *dev, 
{

	int nr = to_sensor_dev_attr(attr)->index;

	struct lm85_data *data = lm85_update_device(dev);

	return sprintf(buf, "%d\n", FREQ_FROM_REG(data->freq_map,

						  data->pwm_freq[nr]));

	int freq;



	if (IS_ADT7468_HFPWM(data))

		freq = 22500;

	else

		freq = FREQ_FROM_REG(data->freq_map, data->pwm_freq[nr]);



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

}



static ssize_t set_pwm_freq(struct device *dev,
@@ -580,10 +589,22 @@ static ssize_t set_pwm_freq(struct device *dev, 
	long val = simple_strtol(buf, NULL, 10);



	mutex_lock(&data->update_lock);

	/* The ADT7468 has a special high-frequency PWM output mode,

	 * where all PWM outputs are driven by a 22.5 kHz clock.

	 * This might confuse the user, but there's not much we can do. */

	if (data->type == adt7468 && val >= 11300) {	/* High freq. mode */

		data->cfg5 &= ~ADT7468_HFPWM;

		lm85_write_value(client, ADT7468_REG_CFG5, data->cfg5);

	} else {					/* Low freq. mode */

		data->pwm_freq[nr] = FREQ_TO_REG(data->freq_map, val);

		lm85_write_value(client, LM85_REG_AFAN_RANGE(nr),

				 (data->zone[nr].range << 4)

				 | data->pwm_freq[nr]);

		if (data->type == adt7468) {

			data->cfg5 |= ADT7468_HFPWM;

			lm85_write_value(client, ADT7468_REG_CFG5, data->cfg5);

		}

	}

	mutex_unlock(&data->update_lock);

	return count;

}