Instead of using the literal value for the number of nanoseconds per
second, use the macro instead to increase readability.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The of_node_put() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The Pistachio SOC from Imagination Technologies includes a Pulse Width
Modulation DAC which produces 1 to 4 digital bit-outputs which represent
digital waveforms. These PWM outputs are primarily in charge of controlling
backlight LED devices.
Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Naidu Tellapati <Naidu.Tellapati@imgtec.com>
Signed-off-by: Sai Masarapu <Sai.Masarapu@imgtec.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Reviewed-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
[thierry.reding: fixup license header as discussed on list]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This patch introduces a bitmap which is used to keep track of the
pwm channels which have been configured in a pwm chip.
The method used earlier to find the number of configured channels,
was to count the pwmdevices with PWMF_REQUESTED field set
and period value configured. This was not correct and failed
when of_pwm_get()/pwm_get() and then pwm_config() was used.
Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The slow and system clock should never return a rate of zero, but this
might happen if the clocks property defined in the DT is referencing the
wrong clocks.
Prevent any division by zero from happening by testing the clk_freq
value before calling do_div().
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The include/linux/clk.h header defines dummy implementations for the
various clk_*() functions if HAVE_CLK is not selected to improve build
coverage in randconfig builds.
The dummy implementation of clk_get_rate() returns 0, which causes the
Atmel HLCDC PWM driver's atmel_hlcdc_pwm_config() implementation to end
up calling:
do_div(clk_period_ns, 0)
On x86, do_div(n, base) will end up evaluating to this:
n >>= ilog2(base)
with base = 0, the implementation of ilog2() will call ____ilog2_NaN(),
which is purposely undefined and results in a linker failure:
ERROR: "____ilog2_NaN" [drivers/pwm/pwm-atmel-hlcdc.ko] undefined!
The implementation of do_div() checks that base is a power of 2 before
calling ilog2(). The compiler doesn't optimize this away, presumably
because is_power_of_2() is an inline function and the compiler doesn't
or can't inspect it closely enough. ilog2() being a macro it still ends
up generating the ____ilog2_NaN() because of the constant 0.
The root of the problem is that the driver really should be checking
before possibly dividing by zero. That should eventually be fixed, but
for now just assume that the clock runs at a sensible frequency when
available.
Reported-by: Jim Davis <jim.epost@gmail.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Pull pwm updates from Thierry Reding:
"There are two new drivers, one for the BCM2835 (Raspberry Pi) and one
used in conjunction with the LCD controller on various Atmel SoCs.
The Samsung PWM driver can now be built for 64-bit ARM (Exynos7).
A couple of fixes have been applied to the FTM PWM driver and system
sleep support was added"
* tag 'pwm/for-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
pwm: atmel-hlcdc: add at91sam9x5 and sama5d3 errata handling
pwm: ftm: Add Power Management support for FTM PWM
pwm: ftm: Add regmap rbtree type cache support
pwm: ftm: Correctly track usage count
pwm: samsung: Allow Samsung PWM driver to be enabled on Exynos7
pwm: add DT bindings documentation for atmel-hlcdc-pwm driver
pwm: add support for atmel-hlcdc-pwm device
pwm: Add BCM2835 PWM driver
at91sam9x5 has an errata forbidding the use of slow clk as a clk source and
sama5d3 SoCs has another errata forbidding the use of div1 prescaler.
Take both of these erratas into account.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
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>
To re-use the existing PWM driver for 64-bit ARM based Exynos7 SoC, make
the driver depend on ARCH_EXYNOS along with PLAT_SAMSUNG.
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Pull pwm changes from Thierry Reding:
"There are no new drivers here, only a couple of fixes all over the
place"
* tag 'pwm/for-3.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
pwm: Let PWM_CLPS711X depend on HAS_IOMEM
pwm: atmel: Fix calculation of prescale value
pwm: Fix uninitialized warnings in pwm_get()
pwm: rockchip: Allow polarity invert on rk3288
pwm: imx: Avoid sample FIFO overflow for i.MX PWM version2
pwm: imx: Cleanup indentation for register definitions
pwm: imx: Fix the macro MX3_PWMCR_PRESCALER(x) definition
pwm: Fix possible ZERO_SIZE_PTR pointer dereferencing error.
pwm: lpss: make it buildable only on X86
pwm: lpss: use c99 initializers in structures
pwm: lpss: Fix build failure on PowerPC
pwm: lpss: pci: Move to use pcim_enable_device()
pwm: lpss: Properly split driver to parts
pwm: lpss: Add ACPI and PCI IDs for Intel Braswell
pwm: fsl-ftm: Select REGMAP_MMIO
pwm: fsl-ftm: Document 'big-endian' property
pwm: fsl-ftm: Convert to direct regmap API usage
pwm: fsl-ftm: Clean up the code
The prescale value used for calculating the period was incremented
afterwards, thus the resulting prescale value is by one too high.
This resulted in a PWM frequency only half as high as requested.
This patch moves the 64 bit division out of the prescale loop to
correct the above issue and make the calculation more efficient.
Signed-off-by: Nikolaus Voss <n.voss@weinmann-emt.de>
Tested-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Pull "Second batch of AT91 cleanup for 3.18" from Nicolas Ferre:
- Timer Counter (TC) fixup and cleanup:
- fix segmentation fault when kexec-ing a kernel by masking
TC interrupts at shutdown and probe time
- use modern driver model: devm_*, probe function, sanitize IRQ request
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
* tag 'at91-cleanup2' of git://github.com/at91linux/linux-at91:
clocksource: tcb_clksrc: sanitize IRQ request
ARM: at91/tclib: mask interruptions at shutdown and probe
ARM: at91/tclib: move initialization from alloc to probe
ARM: at91/tclib: prefer using of devm_* functions
Move resource retrieval from atmel_tc_alloc to tc_probe to avoid lately
reporting resource related issues when a TC block user request a TC block.
Moreover, resources retrieval are usually done in the probe function,
thus moving them add some consistency with other drivers.
Initialization is done once, ie not every time a tc block is requested.
If it fails, the device is not appended to the list of tc blocks.
Furhermore, the device id is retrieved at probe as well, avoiding parsing
DT every time the user requests of tc block.
Signed-off-by: Gaël PORTAY <gael.portay@gmail.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
With some versions of gcc (e.g. 4.1.2):
drivers/pwm/core.c: In function ‘pwm_get’:
drivers/pwm/core.c:610: warning: ‘polarity’ may be used uninitialized in this function
drivers/pwm/core.c:609: warning: ‘period’ may be used uninitialized in this function
While these are false positives, we can get rid of them by refactoring
the code to store a pointer to the best match, as suggested before by
Thierry Reding. This does require moving the mutex_unlock() down.
Fixes: d717ea73e3 ("pwm: Fix period and polarity in pwm_get() for non-perfect matches")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The rk3288 has the ability to invert the polarity of the PWM. Let's
enable that ability. Note that this increases pwm_cells to 3 for
rk3288.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Caesar Wang <caesar.wang@rock-chips.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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>
Thierry Reding
Markus Elfring
Naidu Tellapati
Ajit Pal Singh
Alexandre Belloni
Boris BREZILLON
Linus Torvalds
Xiubo Li
Abhilash Kesavan
Bart Tanghe
Greg Kroah-Hartman
Wolfram Sang
Chen Gang
Nikolaus Voss
Arnd Bergmann
Gaël PORTAY
Geert Uytterhoeven
Doug Anderson
Liu Ying