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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-11 14:06:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-11 14:06:55 -0700
commit7f33e7241d3dbad3c0563fd1fc79fc9380b5c351 (patch)
tree4f0f72e0954e9a5a60679780a4cdf0bf243d47e1 /Documentation
parent2dc24b0d0636349d403ae803bbad0c84f6c2ea57 (diff)
parent39fd3f99aba3f7683fc9b62e916e4c886a1cb6b0 (diff)
downloadlinux-7f33e7241d3dbad3c0563fd1fc79fc9380b5c351.tar.gz
Merge tag 'pwm/for-3.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
Pull pwm changes from Thierry Reding:
 "The majority of these changes are cleanups and fixes across all
  drivers.  Redundant error messages are removed and more PWM
  controllers set the .can_sleep flag to signal that they can't be used
  in atomic context.

  Support is added for the Broadcom Kona family of SoCs and the Intel
  LPSS driver can now probe PCI devices in addition to ACPI devices.
  Upon shutdown, the pwm-backlight driver will now power off the
  backlight.  It also uses the new descriptor-based GPIO API for more
  concise GPIO handling.

  A large chunk of these changes also converts platforms to use the
  lookup mechanism rather than relying on the global number space to
  reference PWM devices.  This is largely in preparation for more
  unification and cleanups in future patches.  Eventually it will allow
  the legacy PWM API to be removed"

* tag 'pwm/for-3.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (38 commits)
  pwm: fsl-ftm: set pwm_chip can_sleep flag
  pwm: ab8500: Fix wrong value shift for disable/enable PWM
  pwm: samsung: do not set manual update bit in pwm_samsung_config
  pwm: lp3943: Set pwm_chip can_sleep flag
  pwm: atmel: set pwm_chip can_sleep flag
  pwm: mxs: set pwm_chip can_sleep flag
  pwm: tiehrpwm: inline accessor functions
  pwm: tiehrpwm: don't build PM related functions when not needed
  pwm-backlight: retrieve configured PWM period
  leds: leds-pwm: retrieve configured PWM period
  ARM: pxa: hx4700: use PWM_LOOKUP to initialize struct pwm_lookup
  ARM: shmobile: armadillo: use PWM_LOOKUP to initialize struct pwm_lookup
  ARM: OMAP3: Beagle: use PWM_LOOKUP to initialize struct pwm_lookup
  pwm: modify PWM_LOOKUP to initialize all struct pwm_lookup members
  ARM: pxa: hx4700: initialize all the struct pwm_lookup members
  ARM: OMAP3: Beagle: initialize all the struct pwm_lookup members
  pwm: renesas-tpu: remove unused struct tpu_pwm_platform_data
  ARM: shmobile: armadillo: initialize all struct pwm_lookup members
  pwm: add period and polarity to struct pwm_lookup
  pwm: twl: Really disable twl6030 PWMs
  ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/pwm/bcm-kona-pwm.txt21
-rw-r--r--Documentation/pwm.txt10
2 files changed, 30 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/pwm/bcm-kona-pwm.txt b/Documentation/devicetree/bindings/pwm/bcm-kona-pwm.txt
new file mode 100644
index 000000000000..8eae9fe7841c
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/bcm-kona-pwm.txt
@@ -0,0 +1,21 @@
+Broadcom Kona PWM controller device tree bindings
+
+This controller has 6 channels.
+
+Required Properties :
+- compatible: should contain "brcm,kona-pwm"
+- reg: physical base address and length of the controller's registers
+- clocks: phandle + clock specifier pair for the external clock
+- #pwm-cells: Should be 3. See pwm.txt in this directory for a
+  description of the cells format.
+
+Refer to clocks/clock-bindings.txt for generic clock consumer properties.
+
+Example:
+
+pwm: pwm@3e01a000 {
+	compatible = "brcm,bcm11351-pwm", "brcm,kona-pwm";
+	reg = <0x3e01a000 0xc4>;
+	clocks = <&pwm_clk>;
+	#pwm-cells = <3>;
+};
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 93cb97974986..ca895fd211e4 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -19,7 +19,8 @@ should instead register a static mapping that can be used to match PWM
 consumers to providers, as given in the following example:
 
 	static struct pwm_lookup board_pwm_lookup[] = {
-		PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight", NULL),
+		PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight", NULL,
+			   50000, PWM_POLARITY_NORMAL),
 	};
 
 	static void __init board_init(void)
@@ -97,6 +98,13 @@ pwm_chip as argument which provides a description of the PWM chip, the
 number of PWM devices provided by the chip and the chip-specific
 implementation of the supported PWM operations to the framework.
 
+When implementing polarity support in a PWM driver, make sure to respect the
+signal conventions in the PWM framework. By definition, normal polarity
+characterizes a signal starts high for the duration of the duty cycle and
+goes low for the remainder of the period. Conversely, a signal with inversed
+polarity starts low for the duration of the duty cycle and goes high for the
+remainder of the period.
+
 Locking
 -------