Lines Matching refs:PWM

2 Pulse Width Modulation (PWM) interface
5 This provides an overview about the Linux PWM interface
9 the Linux PWM API (although they could). However, PWMs are often
12 this kind of flexibility the generic PWM API exists.
17 Users of the legacy PWM API use unique IDs to refer to PWM devices.
19 Instead of referring to a PWM device via its unique ID, board setup code
20 should instead register a static mapping that can be used to match PWM
39 consumer name. pwm_put() is used to free the PWM device. Managed variants of
42 After being requested, a PWM has to be configured using::
46 This API controls both the PWM period/duty_cycle config and the
49 PWM devices can be used from atomic context, if the PWM does not sleep. You
54 If false, the PWM can also be configured from atomic context with::
58 As a consumer, don't rely on the output's state for a disabled PWM. If it's
63 There is also a usage_power setting: If set, the PWM driver is only required to
74 The PWM user API also allows one to query the PWM state that was passed to the
80 In addition to the PWM state, the PWM API also exposes PWM arguments, which
81 are the reference PWM config one should use on this PWM.
82 PWM arguments are usually platform-specific and allows the PWM user to only
85 be used to set the initial PWM config (usually done in the probe function
86 of the PWM user). PWM arguments are retrieved with pwm_get_args().
88 All consumers should really be reconfiguring the PWM upon resume as
97 /sys/class/pwm/. Each probed PWM controller/chip will be exported as
98 pwmchipN, where N is the base of the PWM chip. Inside the directory you
102     The number of PWM channels this chip supports (read-only).
105     Exports a PWM channel for use with sysfs (write-only).
108    Unexports a PWM channel from sysfs (write-only).
110 The PWM channels are numbered using a per-chip index from 0 to npwm-1.
112 When a PWM channel is exported a pwmX directory will be created in the
117     The total period of the PWM signal (read/write).
119     time of the PWM.
122     The active time of the PWM signal (read/write).
126     Changes the polarity of the PWM signal (read/write).
127     Writes to this property only work if the PWM chip supports changing
132     Enable/disable the PWM signal (read/write).
137 Implementing a PWM driver
143 to have multiple PWM drivers in the system. For this reason it's mandatory
144 for new drivers to use the generic PWM framework.
146 A new PWM controller/chip can be allocated using pwmchip_alloc(), then
149 pwm_chip as argument which provides a description of the PWM chip, the number
150 of PWM devices provided by the chip and the chip-specific implementation of the
151 supported PWM operations to the framework.
153 When implementing polarity support in a PWM driver, make sure to respect the
154 signal conventions in the PWM framework. By definition, normal polarity
162 atomicity in the PWM config workflow, which is required when the PWM controls
165 The implementation of ->get_state() (a method used to retrieve initial PWM
166 state) is also encouraged for the same reason: letting the PWM user know
167 about the current PWM state would allow him to avoid glitches.
175 The PWM core list manipulations are protected by a mutex, so pwm_get()
177 PWM core does not enforce any locking to pwm_enable(), pwm_disable() and
184 Currently a PWM can only be configured with period_ns and duty_ns. For several