Re: [v4,4/6] pmbus: max31785: Add fan control

From: Andrew Jeffery
Date: Thu Nov 09 2017 - 22:10:33 EST


On Sun, 2017-11-05 at 07:04 -0800, Guenter Roeck wrote:
> On Fri, Nov 03, 2017 at 03:53:04PM +1100, Andrew Jeffery wrote:
> > The implementation makes use of the new fan control virtual registers
> > exposed by the pmbus core. It mixes use of the default implementations
> > with some overrides via the read/write handlers to handle FAN_COMMAND_1
> > on the MAX31785, whose definition breaks the value range into various
> > control bands dependent on RPM or PWM mode.
> >
> > Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
> > ---
> > Documentation/hwmon/max31785 | 4 ++
> > drivers/hwmon/pmbus/max31785.c | 104 ++++++++++++++++++++++++++++++++++++++++-
> > 2 files changed, 107 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/hwmon/max31785 b/Documentation/hwmon/max31785
> > index 45fb6093dec2..e9edbf11948f 100644
> > --- a/Documentation/hwmon/max31785
> > +++ b/Documentation/hwmon/max31785
> > @@ -32,6 +32,7 @@ Sysfs attributes
> > fan[1-4]_alarm Fan alarm.
> > fan[1-4]_fault Fan fault.
> > fan[1-4]_input Fan RPM.
> > +fan[1-4]_target Fan input target
> >
> > in[1-6]_crit Critical maximum output voltage
> > in[1-6]_crit_alarm Output voltage critical high alarm
> > @@ -44,6 +45,9 @@ in[1-6]_max_alarm Output voltage high alarm
> > in[1-6]_min Minimum output voltage
> > in[1-6]_min_alarm Output voltage low alarm
> >
> > +pwm[1-4] Fan target duty cycle (0..255)
> > +pwm[1-4]_enable 0: full-speed, 1: manual control, 2: automatic
> > +
> > temp[1-11]_crit Critical high temperature
> > temp[1-11]_crit_alarm Chip temperature critical high alarm
> > temp[1-11]_input Measured temperature
> > diff --git a/drivers/hwmon/pmbus/max31785.c b/drivers/hwmon/pmbus/max31785.c
> > index 9313849d5160..0d97ddf67079 100644
> > --- a/drivers/hwmon/pmbus/max31785.c
> > +++ b/drivers/hwmon/pmbus/max31785.c
> > @@ -20,8 +20,102 @@ enum max31785_regs {
> >
> > #define MAX31785_NR_PAGES 23
> >
> > +static int max31785_get_pwm(struct i2c_client *client, int page)
> > +{
> > + int config;
> > + int command;
> > +
> > + config = pmbus_read_byte_data(client, page, PMBUS_FAN_CONFIG_12);
> > + if (config < 0)
> > + return config;
> > +
> > + command = pmbus_read_word_data(client, page, PMBUS_FAN_COMMAND_1);
> > + if (command < 0)
> > + return command;
> > +
> > + if (!(config & PB_FAN_1_RPM)) {
> > + if (command >= 0x8000)
> > + return 0;
> > + else if (command >= 0x2711)
> > + return 0x2710;
> > +
> > + return command;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int max31785_get_pwm_mode(struct i2c_client *client, int page)
> > +{
> > + int config;
> > + int command;
> > +
> > + config = pmbus_read_byte_data(client, page, PMBUS_FAN_CONFIG_12);
> > + if (config < 0)
> > + return config;
> > +
> > + command = pmbus_read_word_data(client, page, PMBUS_FAN_COMMAND_1);
> > + if (command < 0)
> > + return command;
> > +
> > + if (!(config & PB_FAN_1_RPM)) {
> > + if (command >= 0x8000)
> > + return 2;
> > + else if (command >= 0x2711)
> > + return 0;
> > +
> > + return 1;
> > + }
> > +
> > + return (command >= 0x8000) ? 2 : 1;
> > +}
> > +
> > +static int max31785_read_word_data(struct i2c_client *client, int page,
> > + int reg)
> > +{
> > + int rv;
> > +
> > + switch (reg) {
> > + case PMBUS_VIRT_PWM_1:
> > + rv = max31785_get_pwm(client, page);
> > + if (rv < 0)
> > + return rv;
> > +
> > + rv *= 255;
> > + rv /= 100;
> > + break;
> > + case PMBUS_VIRT_PWM_ENABLE_1:
> > + rv = max31785_get_pwm_mode(client, page);
> > + break;
>
> I do wonder ... does it even make sense to specify generic code
> for the new virtual attributes in the pmbus core code, or would
> it be better to have it all in this driver, at least for now ?

I think I'll pull the generic implementations out in light of my
response on 3/6. At best the generic implementation for the PWM virtual
regs is a guess. We can always put it back if others come to need it.

Cheers,

Andrew

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