Commit Graph

9 Commits

Author SHA1 Message Date
Stefan Agner ad06fdeeef pwm: fsl-ftm: Use flat regmap cache
Use flat regmap cache to avoid lockdep warning at probe:

[    0.697285] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x15c/0x160()
[    0.697449] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))

The RB-tree regmap cache needs to allocate new space on first writes.
However, allocations in an atomic context (e.g. when a spinlock is held)
are not allowed. The function regmap_write calls map->lock, which
acquires a spinlock in the fast_io case. Since the pwm-fsl-ftm driver
uses MMIO, the regmap bus of type regmap_mmio is being used which has
fast_io set to true.

The MMIO space of the pwm-fsl-ftm driver is reasonable condense, hence
using the much faster flat regmap cache is anyway the better choice.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-04-14 16:54:00 +02:00
Stefan Agner 816aec2325 pwm: fsl-ftm: Fix clock enable/disable when using PM
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>
2015-12-16 16:54:32 +01:00
Xiubo Li 97d0b42e39 pwm: ftm: Add Power Management support for FTM PWM
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>
2014-12-01 10:48:54 +01:00
Xiubo Li 49599cf6bb pwm: ftm: Add regmap rbtree type cache support
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>
2014-12-01 10:44:48 +01:00
Xiubo Li 8e6e765102 pwm: ftm: Correctly track usage count
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>
2014-12-01 10:43:45 +01:00
Xiubo Li 42fa98a9c3 pwm: fsl-ftm: Convert to direct regmap API usage
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>
2014-08-20 10:10:12 +02:00
Xiubo Li cd6d92d2aa pwm: fsl-ftm: Clean up the code
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>
2014-08-20 10:09:54 +02:00
Axel Lin 39fd3f99ab pwm: fsl-ftm: set pwm_chip can_sleep flag
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>
2014-05-23 09:11:21 +02:00
Xiubo Li b505183b51 pwm: Add Freescale FTM PWM driver support
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>
2014-03-18 18:01:56 +01:00