The i.MX PWM version2 is embedded in several i.MX SoCs, such as i.MX27,
i.MX51 and i.MX6SL. There is a 4-word (16 bit) sample FIFO in this IP.
Each FIFO slot determines the duty period of a PWM waveform in one full
cycle. The IP spec mentions that we should not write a fourth sample
because the FIFO will become full and triggers a FIFO write error (FWE)
which will prevent the PWM from starting once it is enabled. In order
to avoid any sample FIFO overflow issue, this patch clears all sample
FIFO by doing software reset in the configuration hook when the
controller is disabled or waits for a full PWM cycle to get a
relinquished FIFO slot when the controller is enabled and the FIFO is
fully loaded.
The FIFO overflow issue can be reproduced by the following commands on
the i.MX6SL EVK platform, assuming we use PWM2 for the debug LED which
is driven by the pin HSIC_STROBE and the maximal brightness is 255.
echo 0 > /sys/class/leds/user/brightness
echo 0 > /sys/class/leds/user/brightness
echo 0 > /sys/class/leds/user/brightness
echo 0 > /sys/class/leds/user/brightness
echo 255 > /sys/class/leds/user/brightness
Here, FWE happens (PWMSR register reads 0x58) and the LED can not be
lighten.
Another way to reproduce the FIFO overflow issue is to run this script:
while true;
do echo 255 > /sys/class/leds/user/brightness;
done
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawn.guo@freescale.com>
Cc: Lothar Waßmann <LW@KARO-electronics.de>
Cc: linux-pwm@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Acked-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The .config() hook imx_pwm_config() calls clk APIs like clk_prepare()
and clk_get_rate(), which might sleep, so we need to set can_sleep flag
on pwm_chip.
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The site-specific OOM messages are unnecessary, because they
duplicate the MM subsystem generic OOM message.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The data structure of_match_ptr() protects is always compiled in.
Hence of_match_ptr() is not needed.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
'of_match_ptr' is defined in linux/of.h. Include it explicitly.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Some drivers don't set the .owner fields of the struct device_driver or
struct pwm_ops, which causes the module usage count to become wrong.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
devm_ioremap_resource does sanity checks on the given resource. No need to
duplicate this in the driver.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
We can test PWMF_ENABLED bit to know if pwm is enabled or not.
Thus remove enabled field from struct imx_chip.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Convert all uses of devm_request_and_ioremap() to the newly introduced
devm_ioremap_resource() which provides more consistent error handling.
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A new driver has been added for the SPEAr platform and the TWL4030/6030
driver has been replaced by two drivers that control the regular PWMs
and the PWM driven LEDs provided by the chips.
The vt8500, tiecap, tiehrpwm, i.MX, LPC32xx and Samsung drivers have all
been improved and the device tree bindings now support the PWM signal
polarity.
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Merge tag 'for-3.8-rc1' of git://gitorious.org/linux-pwm/linux-pwm
Pull pwm changes from Thierry Reding:
"A new driver has been added for the SPEAr platform and the
TWL4030/6030 driver has been replaced by two drivers that control the
regular PWMs and the PWM driven LEDs provided by the chips.
The vt8500, tiecap, tiehrpwm, i.MX, LPC32xx and Samsung drivers have
all been improved and the device tree bindings now support the PWM
signal polarity."
Fix up trivial conflicts due to __devinit/exit removal.
* tag 'for-3.8-rc1' of git://gitorious.org/linux-pwm/linux-pwm: (21 commits)
pwm: samsung: add missing s3c->pwm_id assignment
pwm: lpc32xx: Set the chip base for dynamic allocation
pwm: lpc32xx: Properly disable the clock on device removal
pwm: lpc32xx: Fix the PWM polarity
pwm: i.MX: eliminate build warning
pwm: Export of_pwm_xlate_with_flags()
pwm: Remove pwm-twl6030 driver
pwm: New driver to support PWM driven LEDs on TWL4030/6030 series of PMICs
pwm: New driver to support PWMs on TWL4030/6030 series of PMICs
pwm: pwm-tiehrpwm: pinctrl support
pwm: tiehrpwm: Add device-tree binding
pwm: pwm-tiehrpwm: Adding TBCLK gating support.
pwm: pwm-tiecap: pinctrl support
pwm: tiecap: Add device-tree binding
pwm: Add TI PWM subsystem driver
pwm: Device tree support for PWM polarity
pwm: vt8500: Ensure PWM clock is enabled during pwm_config
pwm: vt8500: Fix build error
pwm: spear: Staticize spear_pwm_config()
pwm: Add SPEAr PWM chip driver support
...
compiling the i.MX pwm driver produces the following warning:
|drivers/pwm/pwm-imx.c: In function 'imx_pwm_probe':
|drivers/pwm/pwm-imx.c:281:7: warning: assignment discards qualifiers from pointer target type
Apply a 'const' attribute to the affected variable declaration.
Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
CONFIG_HOTPLUG is going away as an option so __devexit is no
longer needed.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CONFIG_HOTPLUG is going away as an option so __devinit is no longer
needed.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CONFIG_HOTPLUG is going away as an option so __devexit_p is no longer
needed.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The i.MX PWM core has two clocks: The ipg clock and the ipg highfreq
(peripheral) clock. The ipg clock has to be enabled for this hardware
to work. The actual PWM output can either be driven by the ipg clock
or the ipg highfreq. The ipg highfreq has the advantage that it runs
even when the SoC is in low power modes.
This patch requests both clocks and enables the ipg clock for accessing
registers and the peripheral clock to actually turn on the PWM.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
The i.MX PWM module has two clocks: The ipg clock and the ipg highfreq
(peripheral) clock. The ipg clock has to be enabled for this hardware
to work. The actual PWM output can either be driven by the ipg clock
or the ipg highfreq. The ipg highfreq has the advantage that it runs
even when the SoC is in low power modes.
Use the always running clock also on i.MX25.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
At the same time remove platform based support. No user for
this driver has made it into mainline so far, so all we break
is out of tree stuff.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
We used to enable/disable the PWM only by switching the
clock on or off. Instead, use the dedicated register bits.
These differ on different SoCs, so introduce a SoC specific
function for this.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
The PWM core makes sure that pwm_enable/disable are called only
once. Still keep the enabled state since we will need it in
pwm_config.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
To cleanup the code and to make it easier to support different
SoCs.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Move the driver to drivers/pwm/ and convert it to use the framework.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
[eric@eukrea.com: set chip.dev to prevent probe failure]
[eric@eukrea.com: fix pwmchip_add return code test]
Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
