[PATCHv7 0/4] Add Freescale FTM PWM driver.

[Xiubo Li]

This patch series is the Freescale FTM PWM implementation. And there
are 8 channels most supported by the FTM PWM. This implementation is
only compatible with device tree definition.

This patch series is based on linux-next and has been tested on Vybrid
VF610 Tower board using device tree.


Changes in v7:
- Add big-endian mode support.
- Add FTM mutex lock.
- Add period time check with the current running pwm(s).
- Recode the counter clock source selecting.
- Sort some header files alphabetically, etc.

Changes in v6:
- Remove "fsl,pwm-counter-clk".

Changes in v5:
- Remove active/idle pinctrl stuff.

Changes in v4:
- Check for the result and return an error for devm_kzalloc().
- Move pinmux setting from the SoC file to the board specific file.
- Revise the written mistake of 'ret |= FTMSC_CLKEXT;' --> 'reg |= FTMSC_CLKEXT;'.


Changes in v3:
- Remove "availabe" field.
- Remove "fsl,pwm-avaliable-chs" property.
- ...

Changes in v2:
- Remove PWM CPWM/EPWM feature and sysfs.
- Remove some redundant code.
- Revise some code for more readable.
- Remove "fsl,pwm-clk-ps", "fsl,pwm-number", "fsl,pwm-channels",etc.
- Add "fsl,pwm-avaliable-chs", "fsl,pwm-counter-clk", etc.
- Support 8 channels default in dtsi file.
- Add counter clock source selection.
- Rename some function name, macro name, etc.
- Use PWM's and OF's existing function interfaces.
- Split clk_unprepare_enable to clk_unprepare and clk_enable,etc.
- ...

Added in v1:
- Add Freescale FTM PWM driver support.
- Add Freescale FTM PWM node for VF610.
- Enable Enables FTM PWM device for Vybrid VF610 TOWER.
- Add device tree bindings for Freescale.