Hi Bjorn, On Mittwoch, 16. Februar 2022 05:56:20 CET Bjorn Andersson wrote: > The Light Pulse Generator (LPG) is a PWM-block found in a wide range of > PMICs from Qualcomm. These PMICs typically comes with 1-8 LPG instances, > with their output being routed to various other components, such as > current sinks or GPIOs. > > Each LPG instance can operate on fixed parameters or based on a shared > lookup-table, altering the duty cycle over time. This provides the means > for hardware assisted transitions of LED brightness. > > A typical use case for the fixed parameter mode is to drive a PWM > backlight control signal, the driver therefor allows each LPG instance > to be exposed to the kernel either through the LED framework or the PWM > framework. > > A typical use case for the LED configuration is to drive RGB LEDs in > smartphones etc, for which the driver supports multiple channels to be > ganged up to a MULTICOLOR LED. In this configuration the pattern > generators will be synchronized, to allow for multi-color patterns. > > The idea of modelling this as a LED driver ontop of a PWM driver was > considered, but setting the properties related to patterns does not fit > in the PWM API. Similarly the idea of just duplicating the lower bits in > a PWM and LED driver separately was considered, but this would not allow > the PWM channels and LEDs to be configured on a per-board basis. The > driver implements the more complex LED interface, and provides a PWM > interface on the side of that, in the same driver. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> Works great on pm8941 / msm8974-fairphone-fp2! Tested-by: Luca Weiss <luca@xxxxxxxxx> Regards Luca > --- > > Changes since v11: > - Extended commit message to cover decision to put pwm_chip in the LED > driver - Added Documentation, in particular for the hw_pattern format > - Added a lock to synchronize requests from LED and PWM frameworks > - Turned out that the 9bit selector differs per channel in some PMICs, so > replaced bitmask in lpg_data with lookup based on QPNP SUBTYPE > - Fixed kerneldoc for the struct device pointer in struct lpg > - Rewrote conditional in lut_free() to make it easier to read > - Corrected and deduplicated max_period expression in lpg_calc_freq() > - Extended nom/dom to numerator/denominator in lpg_calc_freq() > - Replaced 1 << 9 with LPG_RESOLUTION in one more place in lpg_calc_freq() > - Use FIELD_PREP() in lpg_apply_freq() as masks was introduced for reading > the same in get_state() > - Cleaned up the pattern format, to allow specifying both low and high pause > with and without pingpong mode. > - Only update frequency and pwm_value if PWM channel is enabled in > lpg_pwm_apply - Make lpg_pwm_get_state() read the hardware state, in order > to pick up e.g. bootloader backlight configuration > - Use devm_bitmap_zalloc() to allocate the lut_bitmap > - Use dev_err_probe() in lpg_probe() > - Extended Kconfig help text to mention module name and satisfy checkpatch > > Documentation/leds/leds-qcom-lpg.rst | 76 ++ > drivers/leds/Kconfig | 3 + > drivers/leds/Makefile | 3 + > drivers/leds/rgb/Kconfig | 18 + > drivers/leds/rgb/Makefile | 3 + > drivers/leds/rgb/leds-qcom-lpg.c | 1401 ++++++++++++++++++++++++++ > 6 files changed, 1504 insertions(+) > create mode 100644 Documentation/leds/leds-qcom-lpg.rst > create mode 100644 drivers/leds/rgb/Kconfig > create mode 100644 drivers/leds/rgb/Makefile > create mode 100644 drivers/leds/rgb/leds-qcom-lpg.c
