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Subject[PATCH v4 4/6] pmbus: max31785: Add fan control
Date
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@aj.id.au>
---
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;
+ default:
+ rv = -ENODATA;
+ break;
+ }
+
+ return rv;
+}
+
+static const int max31785_pwm_modes[] = { 0x7fff, 0x2710, 0xffff };
+
+static int max31785_write_word_data(struct i2c_client *client, int page,
+ int reg, u16 word)
+{
+ switch (reg) {
+ case PMBUS_VIRT_PWM_ENABLE_1:
+ if (word >= ARRAY_SIZE(max31785_pwm_modes))
+ return -EINVAL;
+
+ return pmbus_update_fan(client, page, 0, 0, PB_FAN_1_RPM,
+ max31785_pwm_modes[word]);
+ default:
+ break;
+ }
+
+ return -ENODATA;
+}
+
#define MAX31785_FAN_FUNCS \
- (PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12)
+ (PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12 | PMBUS_HAVE_PWM12)

#define MAX31785_TEMP_FUNCS \
(PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP)
@@ -32,11 +126,19 @@ enum max31785_regs {
static const struct pmbus_driver_info max31785_info = {
.pages = MAX31785_NR_PAGES,

+ .write_word_data = max31785_write_word_data,
+ .read_word_data = max31785_read_word_data,
+
/* RPM */
.format[PSC_FAN] = direct,
.m[PSC_FAN] = 1,
.b[PSC_FAN] = 0,
.R[PSC_FAN] = 0,
+ /* PWM */
+ .format[PSC_PWM] = direct,
+ .m[PSC_PWM] = 1,
+ .b[PSC_PWM] = 0,
+ .R[PSC_PWM] = 2,
.func[0] = MAX31785_FAN_FUNCS,
.func[1] = MAX31785_FAN_FUNCS,
.func[2] = MAX31785_FAN_FUNCS,
--
2.11.0
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