diff options
author | Scott Wood <scottwood@freescale.com> | 2013-12-14 01:15:24 (GMT) |
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committer | Scott Wood <scottwood@freescale.com> | 2013-12-14 01:15:24 (GMT) |
commit | b7c81aa3ab2ac2c140e278b6d0e9a0b95112cf0b (patch) | |
tree | 87828aaf5f82c7042bfc0307bc4ac499e10f93fb /Documentation/pwm.txt | |
parent | 22c782a4b14773fab7eab3c1db54ad7ad077e9b8 (diff) | |
parent | 78fd82238d0e5716578c326404184a27ba67fd6e (diff) | |
download | linux-fsl-qoriq-b7c81aa3ab2ac2c140e278b6d0e9a0b95112cf0b.tar.xz |
Merge remote-tracking branch 'linus/master' into merge
Conflicts:
Documentation/hwmon/ina2xx
arch/powerpc/Kconfig
arch/powerpc/boot/dts/b4860emu.dts
arch/powerpc/boot/dts/b4qds.dtsi
arch/powerpc/boot/dts/fsl/b4si-post.dtsi
arch/powerpc/boot/dts/fsl/qoriq-sec6.0-0.dtsi
arch/powerpc/boot/dts/p1023rdb.dts
arch/powerpc/boot/dts/t4240emu.dts
arch/powerpc/boot/dts/t4240qds.dts
arch/powerpc/configs/85xx/p1023_defconfig
arch/powerpc/configs/corenet32_smp_defconfig
arch/powerpc/configs/corenet64_smp_defconfig
arch/powerpc/configs/mpc85xx_smp_defconfig
arch/powerpc/include/asm/cputable.h
arch/powerpc/include/asm/device.h
arch/powerpc/include/asm/epapr_hcalls.h
arch/powerpc/include/asm/kvm_host.h
arch/powerpc/include/asm/mpic.h
arch/powerpc/include/asm/pci.h
arch/powerpc/include/asm/ppc-opcode.h
arch/powerpc/include/asm/ppc_asm.h
arch/powerpc/include/asm/reg_booke.h
arch/powerpc/kernel/epapr_paravirt.c
arch/powerpc/kernel/process.c
arch/powerpc/kernel/prom.c
arch/powerpc/kernel/setup-common.c
arch/powerpc/kernel/setup_32.c
arch/powerpc/kernel/setup_64.c
arch/powerpc/kernel/smp.c
arch/powerpc/kernel/swsusp_asm64.S
arch/powerpc/kernel/swsusp_booke.S
arch/powerpc/kvm/book3s_pr.c
arch/powerpc/kvm/booke.c
arch/powerpc/kvm/booke.h
arch/powerpc/kvm/e500.c
arch/powerpc/kvm/e500.h
arch/powerpc/kvm/e500_emulate.c
arch/powerpc/kvm/e500mc.c
arch/powerpc/kvm/powerpc.c
arch/powerpc/perf/e6500-pmu.c
arch/powerpc/platforms/85xx/Kconfig
arch/powerpc/platforms/85xx/Makefile
arch/powerpc/platforms/85xx/b4_qds.c
arch/powerpc/platforms/85xx/c293pcie.c
arch/powerpc/platforms/85xx/corenet_ds.c
arch/powerpc/platforms/85xx/corenet_ds.h
arch/powerpc/platforms/85xx/p1023_rds.c
arch/powerpc/platforms/85xx/p2041_rdb.c
arch/powerpc/platforms/85xx/p3041_ds.c
arch/powerpc/platforms/85xx/p4080_ds.c
arch/powerpc/platforms/85xx/p5020_ds.c
arch/powerpc/platforms/85xx/p5040_ds.c
arch/powerpc/platforms/85xx/smp.c
arch/powerpc/platforms/85xx/t4240_qds.c
arch/powerpc/platforms/Kconfig
arch/powerpc/sysdev/Makefile
arch/powerpc/sysdev/fsl_mpic_timer_wakeup.c
arch/powerpc/sysdev/fsl_msi.c
arch/powerpc/sysdev/fsl_pci.c
arch/powerpc/sysdev/fsl_pci.h
arch/powerpc/sysdev/fsl_soc.h
arch/powerpc/sysdev/mpic.c
arch/powerpc/sysdev/mpic_timer.c
drivers/Kconfig
drivers/clk/Kconfig
drivers/clk/clk-ppc-corenet.c
drivers/cpufreq/Kconfig.powerpc
drivers/cpufreq/Makefile
drivers/cpufreq/ppc-corenet-cpufreq.c
drivers/crypto/caam/Kconfig
drivers/crypto/caam/Makefile
drivers/crypto/caam/ctrl.c
drivers/crypto/caam/desc_constr.h
drivers/crypto/caam/intern.h
drivers/crypto/caam/jr.c
drivers/crypto/caam/regs.h
drivers/dma/fsldma.c
drivers/hwmon/ina2xx.c
drivers/iommu/Kconfig
drivers/iommu/fsl_pamu.c
drivers/iommu/fsl_pamu.h
drivers/iommu/fsl_pamu_domain.c
drivers/iommu/fsl_pamu_domain.h
drivers/misc/Makefile
drivers/mmc/card/block.c
drivers/mmc/core/core.c
drivers/mmc/host/sdhci-esdhc.h
drivers/mmc/host/sdhci-pltfm.c
drivers/mtd/nand/fsl_ifc_nand.c
drivers/net/ethernet/freescale/gianfar.c
drivers/net/ethernet/freescale/gianfar.h
drivers/net/ethernet/freescale/gianfar_ethtool.c
drivers/net/phy/at803x.c
drivers/net/phy/phy_device.c
drivers/net/phy/vitesse.c
drivers/pci/msi.c
drivers/staging/Kconfig
drivers/staging/Makefile
drivers/uio/Kconfig
drivers/uio/Makefile
drivers/uio/uio.c
drivers/usb/host/ehci-fsl.c
drivers/vfio/Kconfig
drivers/vfio/Makefile
include/crypto/algapi.h
include/linux/iommu.h
include/linux/mmc/sdhci.h
include/linux/msi.h
include/linux/netdev_features.h
include/linux/phy.h
include/linux/skbuff.h
include/net/ip.h
include/uapi/linux/vfio.h
net/core/ethtool.c
net/ipv4/route.c
net/ipv6/route.c
Diffstat (limited to 'Documentation/pwm.txt')
-rw-r--r-- | Documentation/pwm.txt | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 7d2b4c9..93cb979 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -39,12 +39,49 @@ New users should use the pwm_get() function and pass to it the consumer device or a consumer name. pwm_put() is used to free the PWM device. Managed variants of these functions, devm_pwm_get() and devm_pwm_put(), also exist. -After being requested a PWM has to be configured using: +After being requested, a PWM has to be configured using: int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); To start/stop toggling the PWM output use pwm_enable()/pwm_disable(). +Using PWMs with the sysfs interface +----------------------------------- + +If CONFIG_SYSFS is enabled in your kernel configuration a simple sysfs +interface is provided to use the PWMs from userspace. It is exposed at +/sys/class/pwm/. Each probed PWM controller/chip will be exported as +pwmchipN, where N is the base of the PWM chip. Inside the directory you +will find: + +npwm - The number of PWM channels this chip supports (read-only). + +export - Exports a PWM channel for use with sysfs (write-only). + +unexport - Unexports a PWM channel from sysfs (write-only). + +The PWM channels are numbered using a per-chip index from 0 to npwm-1. + +When a PWM channel is exported a pwmX directory will be created in the +pwmchipN directory it is associated with, where X is the number of the +channel that was exported. The following properties will then be available: + +period - The total period of the PWM signal (read/write). + Value is in nanoseconds and is the sum of the active and inactive + time of the PWM. + +duty_cycle - The active time of the PWM signal (read/write). + Value is in nanoseconds and must be less than the period. + +polarity - Changes the polarity of the PWM signal (read/write). + Writes to this property only work if the PWM chip supports changing + the polarity. The polarity can only be changed if the PWM is not + enabled. Value is the string "normal" or "inversed". + +enable - Enable/disable the PWM signal (read/write). + 0 - disabled + 1 - enabled + Implementing a PWM driver ------------------------- @@ -57,7 +94,7 @@ for new drivers to use the generic PWM framework. A new PWM controller/chip can be added using pwmchip_add() and removed again with pwmchip_remove(). pwmchip_add() takes a filled in struct pwm_chip as argument which provides a description of the PWM chip, the -number of PWM devices provider by the chip and the chip-specific +number of PWM devices provided by the chip and the chip-specific implementation of the supported PWM operations to the framework. Locking |