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Diffstat (limited to 'Documentation/pwm.txt')
| -rw-r--r-- | Documentation/pwm.txt | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 48f598acdd16..554290ebab94 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -12,14 +12,33 @@ this kind of flexibility the generic PWM API exists. Identifying PWMs ---------------- -Users of the legacy PWM API use unique IDs to refer to PWM devices. One -goal of the new PWM framework is to get rid of this global namespace. +Users of the legacy PWM API use unique IDs to refer to PWM devices. + +Instead of referring to a PWM device via its unique ID, board setup code +should instead register a static mapping that can be used to match PWM +consumers to providers, as given in the following example: + + static struct pwm_lookup board_pwm_lookup[] = { + PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight", NULL), + }; + + static void __init board_init(void) + { + ... + pwm_add_table(board_pwm_lookup, ARRAY_SIZE(board_pwm_lookup)); + ... + } Using PWMs ---------- -A PWM can be requested using pwm_request() and freed after usage with -pwm_free(). After being requested a PWM has to be configured using +Legacy users can request a PWM device using pwm_request() and free it +after usage with pwm_free(). + +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. + +After being requested a PWM has to be configured using: int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); |