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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-09 10:55:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-09 10:55:32 -0700
commit82278fc079542a04e076da34546a7d6dc649b0cc (patch)
tree96d32ea11f41ee6623190f31f4f6a9263f0c9ddc /Documentation
parentbd2843fe1f29f6145c623ae9390f144cefaa611d (diff)
parent7a5938201834a9c25155176d0f5942d48336b244 (diff)
Merge tag 'pwm/for-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
Pull pwm updates from Thierry Reding: "This set of changes introduces the beginnings of a new API that's based around the concept of states that can be atomically applied. Drivers go to various lengths to implement something similar, which indicates that the core should really be providing the necessary framework. On top of that, there is a bit of cleanup as well as improved kerneldoc and integration into the device-drivers DocBook. Regarding drivers there is a new one for the NXP LPC18xx family of SoCs and a couple of fixes for existing drivers (pca9685, Broadcom Kona and Atmel HLCDC)" * tag 'pwm/for-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: ARM: at91: pwm: atmel-hlcdc: Add at91sam9n12 errata pwm: Add NXP LPC18xx PWM/SCT DT binding documentation pwm: NXP LPC18xx PWM/SCT driver pwm-pca9685: Support changing the output frequency pwm-pca9685: Fix several driver bugs pwm: kona: Modify settings application sequence pwm: pca9685: Drop owner assignment pwm: Add to device-drivers documentation pwm: Clean up kerneldoc pwm: Remove useless whitespace pwm: sysfs: Remove unnecessary padding pwm: sysfs: Properly convert from enum to string pwm: Make use of pwm_get_xxx() helpers where appropriate pwm: Add pwm_get_polarity() helper function pwm: Constify PWM device where possible pwm: Add the pwm_is_enabled() helper
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/device-drivers.tmpl27
-rw-r--r--Documentation/devicetree/bindings/pwm/lpc1850-sct-pwm.txt20
2 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index abba93f9d64a..1d6008d51b55 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -490,4 +490,31 @@ X!Ilib/fonts/fonts.c
!Edrivers/hsi/hsi.c
</chapter>
+ <chapter id="pwm">
+ <title>Pulse-Width Modulation (PWM)</title>
+ <para>
+ Pulse-width modulation is a modulation technique primarily used to
+ control power supplied to electrical devices.
+ </para>
+ <para>
+ The PWM framework provides an abstraction for providers and consumers
+ of PWM signals. A controller that provides one or more PWM signals is
+ registered as <structname>struct pwm_chip</structname>. Providers are
+ expected to embed this structure in a driver-specific structure. This
+ structure contains fields that describe a particular chip.
+ </para>
+ <para>
+ A chip exposes one or more PWM signal sources, each of which exposed
+ as a <structname>struct pwm_device</structname>. Operations can be
+ performed on PWM devices to control the period, duty cycle, polarity
+ and active state of the signal.
+ </para>
+ <para>
+ Note that PWM devices are exclusive resources: they can always only be
+ used by one consumer at a time.
+ </para>
+!Iinclude/linux/pwm.h
+!Edrivers/pwm/core.c
+ </chapter>
+
</book>
diff --git a/Documentation/devicetree/bindings/pwm/lpc1850-sct-pwm.txt b/Documentation/devicetree/bindings/pwm/lpc1850-sct-pwm.txt
new file mode 100644
index 000000000000..36e49d4325cd
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/lpc1850-sct-pwm.txt
@@ -0,0 +1,20 @@
+* NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
+
+Required properties:
+ - compatible: Should be "nxp,lpc1850-sct-pwm"
+ - reg: Should contain physical base address and length of pwm registers.
+ - clocks: Must contain an entry for each entry in clock-names.
+ See ../clock/clock-bindings.txt for details.
+ - clock-names: Must include the following entries.
+ - pwm: PWM operating clock.
+ - #pwm-cells: Should be 3. See pwm.txt in this directory for the description
+ of the cells format.
+
+Example:
+ pwm: pwm@40000000 {
+ compatible = "nxp,lpc1850-sct-pwm";
+ reg = <0x40000000 0x1000>;
+ clocks =<&ccu1 CLK_CPU_SCT>;
+ clock-names = "pwm";
+ #pwm-cells = <3>;
+ };