pwm: atmel: add Timer Counter Block PWM driver

Hi,

This patch adds a PWM driver based on Atmel Timer Counter Block. Timer Counter Block is used in Waveform generator mode.

A Timer Counter Block provides up to 6 PWM devices grouped by 2:
* group 0 = PWM 0 and 1
* group 1 = PWM 1 and 2
* group 2 = PMW 3 and 4

PWM devices in a given group must be configured with the same period value.
If a PWM device in a group tries to change the period value and the other device is already configured with a different value an error will be returned.

This driver requires device tree support.
The Timer Counter Block number used to create a PWM chip is given by tc-block field in an "atmel,tcb-pwm" compatible node.

This patch was tested on kizbox board (at91sam9g20 SoC) with pwm-leds.

Regards,

Boris

---
Changes since v1:
- Fix device tree binding Documentation
- Fix Kconfig issues (missing OF dependency, deprecated HAVE_PWM select, ...)
- Fix various coding style issues.
- Cleanup code and add some comments.

Changes since v2:
- Replace kzalloc/kfree with managed versions (devm_kzalloc/devm_kfree).
- Add one cell to device tree binding to support polarity flag.
- Replace min computation (2 div -> 1 mul + 1 div).

Changes since v3:
- Fix device tree binding Documentation
- Fix Kconfig description
- Fix coding style issues (function parameters alignment)
- Replace 1000000000 value with NSEC_PER_SEC macro
- Get rid of newcmr variable in enable/disable functions
- Remove unneeded devm_kfree
- Add missing atmel_tc_free

 .../devicetree/bindings/pwm/atmel-tcb-pwm.txt      |   18 +
 drivers/pwm/Kconfig                                |   12 +
 drivers/pwm/Makefile                               |    1 +
 drivers/pwm/pwm-atmel-tcb.c                        |  428 ++++++++++++++++++++
 4 files changed, 459 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt
 create mode 100644 drivers/pwm/pwm-atmel-tcb.c

new file mode 100644
index 0000000..de0eaed
@@ -0,0 +1,18 @@
+Atmel TCB PWM controller
+
+Required properties:
+- compatible: should be "atmel,tcb-pwm"
+- #pwm-cells: Should be 3.  The first cell specifies the per-chip index
+  of the PWM to use, the second cell is the period in nanoseconds and
+  bit 0 in the third cell is used to encode the polarity of PWM output.
+  Set bit 0 of the third cell in PWM specifier to 1 for inverse polarity &
+  set to 0 for normal polarity.
+- tc-block: The Timer Counter block to use as a PWM chip.
+
+Example:
+
+pwm {
+	compatible = "atmel,tcb-pwm";
+	#pwm-cells = <3>;
+	tc-block = <1>;
+};

index e513cd9..10b6afc 100644
@@ -37,6 +37,18 @@ config PWM_AB8500
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-ab8500.
 
+config PWM_ATMEL_TCB
+	tristate "TC Block PWM"
+	depends on ATMEL_TCLIB && OF
+	help
+	  Generic PWM framework driver for Atmel Timer Counter Block.
+
+	  A Timer Counter Block provides 6 PWM devices grouped by 2.
+	  Devices in a given group must have the same period.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-atmel-tcb.
+
 config PWM_BFIN
 	tristate "Blackfin PWM support"
 	depends on BFIN_GPTIMERS

index 62a2963..94ba21e 100644
@@ -1,5 +1,6 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
+obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o

1.7.0.4