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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)
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 00000000000..8eae9fe7841
--- /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 93cb9797498..ca895fd211e 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
-------