Add support for GMT G762/G763 PWM fan controllers

GMT G762/763 fan speed PWM controller is connected directly to a fan
and performs closed-loop or open-loop control of the fan speed. Two
modes - PWM or DC - are supported by the chip. Introduced driver
provides various knobs to control the operations of the chip (via
sysfs interface). Specific characteristics of the system can be passed
either using board init code or via DT. Documentation for both the
driver and DT bindings are also provided.

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Tested-by: Simon Guinot <simon.guinot@sequanux.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Arnaud Ebalard 2013-06-20 22:21:04 +02:00 committed by Guenter Roeck
parent 31e7ad74f6
commit 594fbe713b
6 changed files with 1309 additions and 0 deletions

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GMT G762/G763 PWM Fan controller
Required node properties:
- "compatible": must be either "gmt,g762" or "gmt,g763"
- "reg": I2C bus address of the device
- "clocks": a fixed clock providing input clock frequency
on CLK pin of the chip.
Optional properties:
- "fan_startv": fan startup voltage. Accepted values are 0, 1, 2 and 3.
The higher the more.
- "pwm_polarity": pwm polarity. Accepted values are 0 (positive duty)
and 1 (negative duty).
- "fan_gear_mode": fan gear mode. Supported values are 0, 1 and 2.
If an optional property is not set in .dts file, then current value is kept
unmodified (e.g. u-boot installed value).
Additional information on operational parameters for the device is available
in Documentation/hwmon/g762. A detailed datasheet for the device is available
at http://natisbad.org/NAS/refs/GMT_EDS-762_763-080710-0.2.pdf.
Example g762 node:
clocks {
#address-cells = <1>;
#size-cells = <0>;
g762_clk: fixedclk {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <8192>;
}
}
g762: g762@3e {
compatible = "gmt,g762";
reg = <0x3e>;
clocks = <&g762_clk>
fan_gear_mode = <0>; /* chip default */
fan_startv = <1>; /* chip default */
pwm_polarity = <0>; /* chip default */
};

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Documentation/hwmon/g762 Normal file
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Kernel driver g762
==================
The GMT G762 Fan Speed PWM Controller is connected directly to a fan
and performs closed-loop or open-loop control of the fan speed. Two
modes - PWM or DC - are supported by the device.
For additional information, a detailed datasheet is available at
http://natisbad.org/NAS/ref/GMT_EDS-762_763-080710-0.2.pdf. sysfs
bindings are described in Documentation/hwmon/sysfs-interface.
The following entries are available to the user in a subdirectory of
/sys/bus/i2c/drivers/g762/ to control the operation of the device.
This can be done manually using the following entries but is usually
done via a userland daemon like fancontrol.
Note that those entries do not provide ways to setup the specific
hardware characteristics of the system (reference clock, pulses per
fan revolution, ...); Those can be modified via devicetree bindings
documented in Documentation/devicetree/bindings/hwmon/g762.txt or
using a specific platform_data structure in board initialization
file (see include/linux/platform_data/g762.h).
fan1_target: set desired fan speed. This only makes sense in closed-loop
fan speed control (i.e. when pwm1_enable is set to 2).
fan1_input: provide current fan rotation value in RPM as reported by
the fan to the device.
fan1_div: fan clock divisor. Supported value are 1, 2, 4 and 8.
fan1_pulses: number of pulses per fan revolution. Supported values
are 2 and 4.
fan1_fault: reports fan failure, i.e. no transition on fan gear pin for
about 0.7s (if the fan is not voluntarily set off).
fan1_alarm: in closed-loop control mode, if fan RPM value is 25% out
of the programmed value for over 6 seconds 'fan1_alarm' is
set to 1.
pwm1_enable: set current fan speed control mode i.e. 1 for manual fan
speed control (open-loop) via pwm1 described below, 2 for
automatic fan speed control (closed-loop) via fan1_target
above.
pwm1_mode: set or get fan driving mode: 1 for PWM mode, 0 for DC mode.
pwm1: get or set PWM fan control value in open-loop mode. This is an
integer value between 0 and 255. 0 stops the fan, 255 makes
it run at full speed.
Both in PWM mode ('pwm1_mode' set to 1) and DC mode ('pwm1_mode' set to 0),
when current fan speed control mode is open-loop ('pwm1_enable' set to 1),
the fan speed is programmed by setting a value between 0 and 255 via 'pwm1'
entry (0 stops the fan, 255 makes it run at full speed). In closed-loop mode
('pwm1_enable' set to 2), the expected rotation speed in RPM can be passed to
the chip via 'fan1_target'. In closed-loop mode, the target speed is compared
with current speed (available via 'fan1_input') by the device and a feedback
is performed to match that target value. The fan speed value is computed
based on the parameters associated with the physical characteristics of the
system: a reference clock source frequency, a number of pulses per fan
revolution, etc.
Note that the driver will update its values at most once per second.

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@ -461,6 +461,16 @@ config SENSORS_G760A
This driver can also be built as a module. If so, the module
will be called g760a.
config SENSORS_G762
tristate "GMT G762 and G763"
depends on I2C
help
If you say yes here you get support for Global Mixed-mode
Technology Inc G762 and G763 fan speed PWM controller chips.
This driver can also be built as a module. If so, the module
will be called g762.
config SENSORS_GL518SM
tristate "Genesys Logic GL518SM"
depends on I2C

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@ -60,6 +60,7 @@ obj-$(CONFIG_SENSORS_F75375S) += f75375s.o
obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
obj-$(CONFIG_SENSORS_FSCHMD) += fschmd.o
obj-$(CONFIG_SENSORS_G760A) += g760a.o
obj-$(CONFIG_SENSORS_G762) += g762.o
obj-$(CONFIG_SENSORS_GL518SM) += gl518sm.o
obj-$(CONFIG_SENSORS_GL520SM) += gl520sm.o
obj-$(CONFIG_SENSORS_GPIO_FAN) += gpio-fan.o

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/*
* Platform data structure for g762 fan controller driver
*
* Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __LINUX_PLATFORM_DATA_G762_H__
#define __LINUX_PLATFORM_DATA_G762_H__
/*
* Following structure can be used to set g762 driver platform specific data
* during board init. Note that passing a sparse structure is possible but
* will result in non-specified attributes to be set to default value, hence
* overloading those installed during boot (e.g. by u-boot).
*/
struct g762_platform_data {
u32 fan_startv;
u32 fan_gear_mode;
u32 pwm_polarity;
u32 clk_freq;
};
#endif /* __LINUX_PLATFORM_DATA_G762_H__ */