From 7ad68e2f970fd84d15ad67ce3216aed05f944a9c Mon Sep 17 00:00:00 2001 From: David Brownell Date: Tue, 11 Nov 2008 17:39:02 -0800 Subject: regulator: sysfs attribute reduction (v2) Clean up the sysfs interface to regulators by only exposing the attributes that can be properly displayed. For example: when a particular regulator method is needed to display the value, only create that attribute when that method exists. This cleaned-up interface is much more comprehensible. Most regulators only support a subset of the possible methods, so often more than half the attributes would be meaningless. Many "not defined" values are no longer necessary. (But handling of out-of-range values still looks a bit iffy.) Documentation is updated to reflect that few of the attributes are *always* present, and to briefly explain why a regulator may not have a given attribute. This adds object code, about a dozen bytes more than was removed by the preceding patch, but saves a bunch of per-regulator data associated with the now-removed attributes. So there's a net reduction in memory footprint. Signed-off-by: David Brownell Signed-off-by: Liam Girdwood --- Documentation/ABI/testing/sysfs-class-regulator | 136 +++++++++++------------- 1 file changed, 60 insertions(+), 76 deletions(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-class-regulator b/Documentation/ABI/testing/sysfs-class-regulator index 3731f6f29bc..873ef1fc156 100644 --- a/Documentation/ABI/testing/sysfs-class-regulator +++ b/Documentation/ABI/testing/sysfs-class-regulator @@ -3,8 +3,9 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called - state. This holds the regulator output state. + Some regulator directories will contain a field called + state. This reports the regulator enable status, for + regulators which can report that value. This will be one of the following strings: @@ -18,7 +19,8 @@ Description: 'disabled' means the regulator output is OFF and is not supplying power to the system.. - 'unknown' means software cannot determine the state. + 'unknown' means software cannot determine the state, or + the reported state is invalid. NOTE: this field can be used in conjunction with microvolts and microamps to determine regulator output levels. @@ -53,9 +55,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called microvolts. This holds the regulator output voltage setting - measured in microvolts (i.e. E-6 Volts). + measured in microvolts (i.e. E-6 Volts), for regulators + which can report that voltage. NOTE: This value should not be used to determine the regulator output voltage level as this value is the same regardless of @@ -67,9 +70,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called microamps. This holds the regulator output current limit - setting measured in microamps (i.e. E-6 Amps). + setting measured in microamps (i.e. E-6 Amps), for regulators + which can report that current. NOTE: This value should not be used to determine the regulator output current level as this value is the same regardless of @@ -81,8 +85,9 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called - opmode. This holds the regulator operating mode setting. + Some regulator directories will contain a field called + opmode. This holds the current regulator operating mode, + for regulators which can report it. The opmode value can be one of the following strings: @@ -92,7 +97,7 @@ Description: 'standby' 'unknown' - The modes are described in include/linux/regulator/regulator.h + The modes are described in include/linux/regulator/consumer.h NOTE: This value should not be used to determine the regulator output operating mode as this value is the same regardless of @@ -104,9 +109,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called min_microvolts. This holds the minimum safe working regulator - output voltage setting for this domain measured in microvolts. + output voltage setting for this domain measured in microvolts, + for regulators which support voltage constraints. NOTE: this will return the string 'constraint not defined' if the power domain has no min microvolts constraint defined by @@ -118,9 +124,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called max_microvolts. This holds the maximum safe working regulator - output voltage setting for this domain measured in microvolts. + output voltage setting for this domain measured in microvolts, + for regulators which support voltage constraints. NOTE: this will return the string 'constraint not defined' if the power domain has no max microvolts constraint defined by @@ -132,10 +139,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called min_microamps. This holds the minimum safe working regulator output current limit setting for this domain measured in - microamps. + microamps, for regulators which support current constraints. NOTE: this will return the string 'constraint not defined' if the power domain has no min microamps constraint defined by @@ -147,10 +154,10 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called max_microamps. This holds the maximum safe working regulator output current limit setting for this domain measured in - microamps. + microamps, for regulators which support current constraints. NOTE: this will return the string 'constraint not defined' if the power domain has no max microamps constraint defined by @@ -185,7 +192,7 @@ Date: April 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called requested_microamps. This holds the total requested load current in microamps for this regulator from all its consumer devices. @@ -204,125 +211,102 @@ Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_mem_microvolts. This holds the regulator output voltage setting for this domain measured in microvolts when - the system is suspended to memory. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to memory voltage defined by - platform code. + the system is suspended to memory, for voltage regulators + implementing suspend voltage configuration constraints. What: /sys/class/regulator/.../suspend_disk_microvolts Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_disk_microvolts. This holds the regulator output voltage setting for this domain measured in microvolts when - the system is suspended to disk. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to disk voltage defined by - platform code. + the system is suspended to disk, for voltage regulators + implementing suspend voltage configuration constraints. What: /sys/class/regulator/.../suspend_standby_microvolts Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_standby_microvolts. This holds the regulator output voltage setting for this domain measured in microvolts when - the system is suspended to standby. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to standby voltage defined by - platform code. + the system is suspended to standby, for voltage regulators + implementing suspend voltage configuration constraints. What: /sys/class/regulator/.../suspend_mem_mode Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_mem_mode. This holds the regulator operating mode setting for this domain when the system is suspended to - memory. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to memory mode defined by - platform code. + memory, for regulators implementing suspend mode + configuration constraints. What: /sys/class/regulator/.../suspend_disk_mode Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_disk_mode. This holds the regulator operating mode - setting for this domain when the system is suspended to disk. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to disk mode defined by - platform code. + setting for this domain when the system is suspended to disk, + for regulators implementing suspend mode configuration + constraints. What: /sys/class/regulator/.../suspend_standby_mode Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_standby_mode. This holds the regulator operating mode setting for this domain when the system is suspended to - standby. - - NOTE: this will return the string 'not defined' if - the power domain has no suspend to standby mode defined by - platform code. + standby, for regulators implementing suspend mode + configuration constraints. What: /sys/class/regulator/.../suspend_mem_state Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_mem_state. This holds the regulator operating state - when suspended to memory. - - This will be one of the following strings: + when suspended to memory, for regulators implementing suspend + configuration constraints. - 'enabled' - 'disabled' - 'not defined' + This will be one of the same strings reported by + the "state" attribute. What: /sys/class/regulator/.../suspend_disk_state Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_disk_state. This holds the regulator operating state - when suspended to disk. - - This will be one of the following strings: + when suspended to disk, for regulators implementing + suspend configuration constraints. - 'enabled' - 'disabled' - 'not defined' + This will be one of the same strings reported by + the "state" attribute. What: /sys/class/regulator/.../suspend_standby_state Date: May 2008 KernelVersion: 2.6.26 Contact: Liam Girdwood Description: - Each regulator directory will contain a field called + Some regulator directories will contain a field called suspend_standby_state. This holds the regulator operating - state when suspended to standby. - - This will be one of the following strings: + state when suspended to standby, for regulators implementing + suspend configuration constraints. - 'enabled' - 'disabled' - 'not defined' + This will be one of the same strings reported by + the "state" attribute. -- cgit v1.2.3 From 9fe5817f196054142b9a13ed78c73b76a29f2ea3 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Wed, 31 Dec 2008 12:52:44 +0000 Subject: regulator: Add basic DocBook manual Add a basic DocBook manual for the regulator API. This is much more skeletal than the existing text documentation, the main benefit is to provide a skeleton for automatic generation of a manual based on the kerneldoc for the API. Since large portions of the text are lifted from the existing text format documentation written by Liam Girdwood much of the credit belongs to him. Signed-off-by: Mark Brown Signed-off-by: Liam Girdwood --- Documentation/DocBook/Makefile | 2 +- Documentation/DocBook/regulator.tmpl | 304 +++++++++++++++++++++++++++++++++++ 2 files changed, 305 insertions(+), 1 deletion(-) create mode 100644 Documentation/DocBook/regulator.tmpl (limited to 'Documentation') diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index 0a08126d309..dc3154e4927 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -12,7 +12,7 @@ DOCBOOKS := z8530book.xml mcabook.xml \ kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \ gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \ genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \ - mac80211.xml debugobjects.xml sh.xml + mac80211.xml debugobjects.xml sh.xml regulator.xml ### # The build process is as follows (targets): diff --git a/Documentation/DocBook/regulator.tmpl b/Documentation/DocBook/regulator.tmpl new file mode 100644 index 00000000000..53f4f8d3b81 --- /dev/null +++ b/Documentation/DocBook/regulator.tmpl @@ -0,0 +1,304 @@ + + + + + + Voltage and current regulator API + + + + Liam + Girdwood + +
+ lrg@slimlogic.co.uk +
+ + + + Mark + Brown + + Wolfson Microelectronics +
+ broonie@opensource.wolfsonmicro.com +
+ + + + + + 2007-2008 + Wolfson Microelectronics + + + 2008 + Liam Girdwood + + + + + This documentation is free software; you can redistribute + it and/or modify it under the terms of the GNU General Public + License version 2 as published by the Free Software Foundation. + + + + 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 + + + + For more details see the file COPYING in the source + distribution of Linux. + + + + + + + + Introduction + + This framework is designed to provide a standard kernel + interface to control voltage and current regulators. + + + The intention is to allow systems to dynamically control + regulator power output in order to save power and prolong + battery life. This applies to both voltage regulators (where + voltage output is controllable) and current sinks (where current + limit is controllable). + + + Note that additional (and currently more complete) documentation + is available in the Linux kernel source under + Documentation/power/regulator. + + + + Glossary + + The regulator API uses a number of terms which may not be + familiar: + + + + + Regulator + + + Electronic device that supplies power to other devices. Most + regulators can enable and disable their output and some can also + control their output voltage or current. + + + + + + Consumer + + + Electronic device which consumes power provided by a regulator. + These may either be static, requiring only a fixed supply, or + dynamic, requiring active management of the regulator at + runtime. + + + + + + Power Domain + + + The electronic circuit supplied by a given regulator, including + the regulator and all consumer devices. The configuration of + the regulator is shared between all the components in the + circuit. + + + + + + Power Management Integrated Circuit + PMIC + + + An IC which contains numerous regulators and often also other + subsystems. In an embedded system the primary PMIC is often + equivalent to a combination of the PSU and southbridge in a + desktop system. + + + + + + + + + Consumer driver interface + + This offers a similar API to the kernel clock framework. + Consumer drivers use get and put operations to acquire and + release regulators. Functions are + provided to enable + and disable the + reguator and to get and set the runtime parameters of the + regulator. + + + When requesting regulators consumers use symbolic names for their + supplies, such as "Vcc", which are mapped into actual regulator + devices by the machine interface. + + + A stub version of this API is provided when the regulator + framework is not in use in order to minimise the need to use + ifdefs. + + + + Enabling and disabling + + The regulator API provides reference counted enabling and + disabling of regulators. Consumer devices use the regulator_enable + and regulator_disable + functions to enable and disable regulators. Calls + to the two functions must be balanced. + + + Note that since multiple consumers may be using a regulator and + machine constraints may not allow the regulator to be disabled + there is no guarantee that calling + regulator_disable will actually cause the + supply provided by the regulator to be disabled. Consumer + drivers should assume that the regulator may be enabled at all + times. + + + + + Configuration + + Some consumer devices may need to be able to dynamically + configure their supplies. For example, MMC drivers may need to + select the correct operating voltage for their cards. This may + be done while the regulator is enabled or disabled. + + + The regulator_set_voltage + and regulator_set_current_limit + functions provide the primary interface for this. + Both take ranges of voltages and currents, supporting drivers + that do not require a specific value (eg, CPU frequency scaling + normally permits the CPU to use a wider range of supply + voltages at lower frequencies but does not require that the + supply voltage be lowered). Where an exact value is required + both minimum and maximum values should be identical. + + + + + Callbacks + + Callbacks may also be registered + for events such as regulation failures. + + + + + + Regulator driver interface + + Drivers for regulator chips register the regulators + with the regulator core, providing operations structures to the + core. A notifier interface + allows error conditions to be reported to the core. + + + Registration should be triggered by explicit setup done by the + platform, supplying a struct + regulator_init_data for the regulator containing + constraint and + supply information. + + + + + Machine interface + + This interface provides a way to define how regulators are + connected to consumers on a given system and what the valid + operating parameters are for the system. + + + + Supplies + + Regulator supplies are specified using struct + regulator_consumer_supply. This is done at + driver registration + time as part of the machine constraints. + + + + + Constraints + + As well as definining the connections the machine interface + also provides constraints definining the operations that + clients are allowed to perform and the parameters that may be + set. This is required since generally regulator devices will + offer more flexibility than it is safe to use on a given + system, for example supporting higher supply voltages than the + consumers are rated for. + + + This is done at driver + registration time by providing a struct + regulation_constraints. + + + The constraints may also specify an initial configuration for the + regulator in the constraints, which is particularly useful for + use with static consumers. + + + + + + API reference + + Due to limitations of the kernel documentation framework and the + existing layout of the source code the entire regulator API is + documented here. + +!Iinclude/linux/regulator/consumer.h +!Iinclude/linux/regulator/machine.h +!Iinclude/linux/regulator/driver.h +!Edrivers/regulator/core.c + + -- cgit v1.2.3