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d2048c4915
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>
354 lines
9.6 KiB
Plaintext
354 lines
9.6 KiB
Plaintext
menuconfig PWM
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bool "Pulse-Width Modulation (PWM) Support"
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help
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Generic Pulse-Width Modulation (PWM) support.
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In Pulse-Width Modulation, a variation of the width of pulses
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in a rectangular pulse signal is used as a means to alter the
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average power of the signal. Applications include efficient
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power delivery and voltage regulation. In computer systems,
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PWMs are commonly used to control fans or the brightness of
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display backlights.
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This framework provides a generic interface to PWM devices
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within the Linux kernel. On the driver side it provides an API
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to register and unregister a PWM chip, an abstraction of a PWM
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controller, that supports one or more PWM devices. Client
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drivers can request PWM devices and use the generic framework
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to configure as well as enable and disable them.
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This generic framework replaces the legacy PWM framework which
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allows only a single driver implementing the required API. Not
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all legacy implementations have been ported to the framework
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yet. The framework provides an API that is backward compatible
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with the legacy framework so that existing client drivers
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continue to work as expected.
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If unsure, say no.
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if PWM
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config PWM_SYSFS
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bool
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default y if SYSFS
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config PWM_AB8500
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tristate "AB8500 PWM support"
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depends on AB8500_CORE && ARCH_U8500
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help
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Generic PWM framework driver for Analog Baseband AB8500.
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To compile this driver as a module, choose M here: the module
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will be called pwm-ab8500.
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config PWM_ATMEL
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tristate "Atmel PWM support"
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depends on ARCH_AT91 || AVR32
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help
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Generic PWM framework driver for Atmel SoC.
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To compile this driver as a module, choose M here: the module
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will be called pwm-atmel.
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config PWM_ATMEL_HLCDC_PWM
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tristate "Atmel HLCDC PWM support"
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depends on MFD_ATMEL_HLCDC
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depends on HAVE_CLK
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help
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Generic PWM framework driver for the PWM output of the HLCDC
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(Atmel High-end LCD Controller). This PWM output is mainly used
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to control the LCD backlight.
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To compile this driver as a module, choose M here: the module
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will be called pwm-atmel-hlcdc.
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config PWM_ATMEL_TCB
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tristate "Atmel TC Block PWM support"
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depends on ATMEL_TCLIB && OF
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help
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Generic PWM framework driver for Atmel Timer Counter Block.
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A Timer Counter Block provides 6 PWM devices grouped by 2.
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Devices in a given group must have the same period.
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To compile this driver as a module, choose M here: the module
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will be called pwm-atmel-tcb.
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config PWM_BCM_KONA
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tristate "Kona PWM support"
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depends on ARCH_BCM_MOBILE
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help
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Generic PWM framework driver for Broadcom Kona PWM block.
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To compile this driver as a module, choose M here: the module
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will be called pwm-bcm-kona.
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config PWM_BCM2835
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tristate "BCM2835 PWM support"
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depends on ARCH_BCM2835
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help
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PWM framework driver for BCM2835 controller (Raspberry Pi)
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To compile this driver as a module, choose M here: the module
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will be called pwm-bcm2835.
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config PWM_BFIN
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tristate "Blackfin PWM support"
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depends on BFIN_GPTIMERS
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help
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Generic PWM framework driver for Blackfin.
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To compile this driver as a module, choose M here: the module
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will be called pwm-bfin.
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config PWM_CLPS711X
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tristate "CLPS711X PWM support"
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depends on ARCH_CLPS711X || COMPILE_TEST
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depends on HAS_IOMEM
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help
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Generic PWM framework driver for Cirrus Logic CLPS711X.
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To compile this driver as a module, choose M here: the module
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will be called pwm-clps711x.
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config PWM_EP93XX
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tristate "Cirrus Logic EP93xx PWM support"
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depends on ARCH_EP93XX
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help
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Generic PWM framework driver for Cirrus Logic EP93xx.
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To compile this driver as a module, choose M here: the module
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will be called pwm-ep93xx.
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config PWM_FSL_FTM
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tristate "Freescale FlexTimer Module (FTM) PWM support"
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depends on OF
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select REGMAP_MMIO
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help
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Generic FTM PWM framework driver for Freescale VF610 and
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Layerscape LS-1 SoCs.
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To compile this driver as a module, choose M here: the module
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will be called pwm-fsl-ftm.
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config PWM_IMX
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tristate "i.MX PWM support"
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depends on ARCH_MXC
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help
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Generic PWM framework driver for i.MX.
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To compile this driver as a module, choose M here: the module
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will be called pwm-imx.
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config PWM_JZ4740
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tristate "Ingenic JZ4740 PWM support"
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depends on MACH_JZ4740
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help
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Generic PWM framework driver for Ingenic JZ4740 based
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machines.
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To compile this driver as a module, choose M here: the module
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will be called pwm-jz4740.
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config PWM_LP3943
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tristate "TI/National Semiconductor LP3943 PWM support"
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depends on MFD_LP3943
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help
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Generic PWM framework driver for LP3943 which supports two PWM
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channels.
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To compile this driver as a module, choose M here: the module
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will be called pwm-lp3943.
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config PWM_LPC32XX
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tristate "LPC32XX PWM support"
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depends on ARCH_LPC32XX
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help
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Generic PWM framework driver for LPC32XX. The LPC32XX SOC has two
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PWM controllers.
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To compile this driver as a module, choose M here: the module
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will be called pwm-lpc32xx.
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config PWM_LPSS
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tristate "Intel LPSS PWM support"
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depends on X86
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help
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Generic PWM framework driver for Intel Low Power Subsystem PWM
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controller.
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To compile this driver as a module, choose M here: the module
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will be called pwm-lpss.
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config PWM_LPSS_PCI
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tristate "Intel LPSS PWM PCI driver"
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depends on PWM_LPSS && PCI
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help
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The PCI driver for Intel Low Power Subsystem PWM controller.
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To compile this driver as a module, choose M here: the module
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will be called pwm-lpss-pci.
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config PWM_LPSS_PLATFORM
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tristate "Intel LPSS PWM platform driver"
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depends on PWM_LPSS && ACPI
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help
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The platform driver for Intel Low Power Subsystem PWM controller.
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To compile this driver as a module, choose M here: the module
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will be called pwm-lpss-platform.
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config PWM_MXS
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tristate "Freescale MXS PWM support"
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depends on ARCH_MXS && OF
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select STMP_DEVICE
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help
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Generic PWM framework driver for Freescale MXS.
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To compile this driver as a module, choose M here: the module
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will be called pwm-mxs.
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config PWM_PCA9685
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tristate "NXP PCA9685 PWM driver"
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depends on OF && I2C
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select REGMAP_I2C
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help
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Generic PWM framework driver for NXP PCA9685 LED controller.
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To compile this driver as a module, choose M here: the module
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will be called pwm-pca9685.
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config PWM_PUV3
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tristate "PKUnity NetBook-0916 PWM support"
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depends on ARCH_PUV3
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help
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Generic PWM framework driver for PKUnity NetBook-0916.
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To compile this driver as a module, choose M here: the module
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will be called pwm-puv3.
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config PWM_PXA
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tristate "PXA PWM support"
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depends on ARCH_PXA
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help
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Generic PWM framework driver for PXA.
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To compile this driver as a module, choose M here: the module
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will be called pwm-pxa.
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config PWM_RENESAS_TPU
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tristate "Renesas TPU PWM support"
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depends on ARCH_SHMOBILE || COMPILE_TEST
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depends on HAS_IOMEM
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help
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This driver exposes the Timer Pulse Unit (TPU) PWM controller found
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in Renesas chips through the PWM API.
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To compile this driver as a module, choose M here: the module
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will be called pwm-renesas-tpu.
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config PWM_ROCKCHIP
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tristate "Rockchip PWM support"
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depends on ARCH_ROCKCHIP
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help
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Generic PWM framework driver for the PWM controller found on
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Rockchip SoCs.
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config PWM_SAMSUNG
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tristate "Samsung PWM support"
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depends on PLAT_SAMSUNG || ARCH_EXYNOS
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help
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Generic PWM framework driver for Samsung.
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To compile this driver as a module, choose M here: the module
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will be called pwm-samsung.
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config PWM_SPEAR
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tristate "STMicroelectronics SPEAr PWM support"
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depends on PLAT_SPEAR
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depends on OF
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help
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Generic PWM framework driver for the PWM controller on ST
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SPEAr SoCs.
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To compile this driver as a module, choose M here: the module
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will be called pwm-spear.
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config PWM_STI
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tristate "STiH4xx PWM support"
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depends on ARCH_STI
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depends on OF
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help
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Generic PWM framework driver for STiH4xx SoCs.
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To compile this driver as a module, choose M here: the module
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will be called pwm-sti.
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config PWM_TEGRA
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tristate "NVIDIA Tegra PWM support"
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depends on ARCH_TEGRA
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help
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Generic PWM framework driver for the PWFM controller found on NVIDIA
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Tegra SoCs.
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To compile this driver as a module, choose M here: the module
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will be called pwm-tegra.
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config PWM_TIECAP
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tristate "ECAP PWM support"
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depends on SOC_AM33XX || ARCH_DAVINCI_DA8XX
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help
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PWM driver support for the ECAP APWM controller found on AM33XX
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TI SOC
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To compile this driver as a module, choose M here: the module
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will be called pwm-tiecap.
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config PWM_TIEHRPWM
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tristate "EHRPWM PWM support"
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depends on SOC_AM33XX || ARCH_DAVINCI_DA8XX
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help
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PWM driver support for the EHRPWM controller found on AM33XX
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TI SOC
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To compile this driver as a module, choose M here: the module
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will be called pwm-tiehrpwm.
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config PWM_TIPWMSS
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bool
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default y if SOC_AM33XX && (PWM_TIECAP || PWM_TIEHRPWM)
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help
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PWM Subsystem driver support for AM33xx SOC.
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PWM submodules require PWM config space access from submodule
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drivers and require common parent driver support.
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config PWM_TWL
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tristate "TWL4030/6030 PWM support"
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depends on TWL4030_CORE
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help
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Generic PWM framework driver for TWL4030/6030.
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To compile this driver as a module, choose M here: the module
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will be called pwm-twl.
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config PWM_TWL_LED
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tristate "TWL4030/6030 PWM support for LED drivers"
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depends on TWL4030_CORE
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help
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Generic PWM framework driver for TWL4030/6030 LED terminals.
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To compile this driver as a module, choose M here: the module
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will be called pwm-twl-led.
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config PWM_VT8500
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tristate "vt8500 PWM support"
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depends on ARCH_VT8500
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help
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Generic PWM framework driver for vt8500.
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To compile this driver as a module, choose M here: the module
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will be called pwm-vt8500.
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endif
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