A FTM PWM instance enables/disables three clocks: The bus clock, the
counter clock and the PWM clock. The bus clock gets enabled on
pwm_request, whereas the counter and PWM clocks will be enabled upon
pwm_enable.
The driver has three closesly related issues when enabling/disabling
clocks during suspend/resume:
- The three clocks are not treated differently in regards to the
individual PWM state enabled/requested. This can lead to clocks
getting disabled which have not been enabled in the first place
(a PWM channel which only has been requested going through
suspend/resume).
- When entering suspend, the current behavior relies on the
FTM_OUTMASK register: If a PWM output is unmasked, the driver
assumes the clocks are enabled. However, some PWM instances
have only 2 channels connected (e.g. Vybrid's FTM1). In that case,
the FTM_OUTMASK reads 0x3 if all channels are disabled, even if
the code wrote 0xff to it before. For those PWM instances, the
current approach to detect enabled PWM signals does not work.
- A third issue applies to the bus clock only, which can get enabled
multiple times (once for each PWM channel of a PWM chip). This is
fine, however when entering suspend mode, the clock only gets
disabled once.
This change introduces a different approach by relying on the enable
and prepared counters of the clock framework and using the frameworks
PWM signal states to address all three issues.
Clocks get disabled during suspend and back enabled on resume
regarding to the PWM channels individual state (requested/enabled).
Since we do not count the clock enables in the driver, this change no
longer clears the Status and Control registers Clock Source Selection
(FTM_SC[CLKS]). However, since we disable the selected clock anyway,
and we explicitly select the clock source on reenabling a PWM channel
this approach should not make a difference in practice.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Add PM support for FTM PWM driver using callback function suspend
and resume in .driver.pm of platform_driver.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This patch is to prepare for adding PM support for FTM PWM driver using
callback function suspend and resume in .driver.pm of platform_driver.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
No matter how many times the FTM PWM is enabled, the use_count will
always be one.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The regmap core supports different endian modes for devices. This patch
convert to direct regmap API usage, preparing to support big endianness
for LS1 SoC.
Using the regmap framework it will be easy to support devices that only
differ in endianness with the same device driver.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This patch intends to prepare for converting to direct regmap API usage.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The implementation of .config(), .enable() and .disable() operations in this
driver may sleep, thus set pwm_chip can_sleep flag.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The FTM PWM device can be found on Vybrid VF610 Tower and
Layerscape LS-1 SoCs.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Alison Wang <b18965@freescale.com>
Signed-off-by: Jingchang Lu <b35083@freescale.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Stefan Agner