linux-kernel - [PATCH v3 0/2] Add support for Microchip's pwm fpga core

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Message-ID: <20220617114442.998357-1-conor.dooley@microchip.com>
Date:   Fri, 17 Jun 2022 12:44:41 +0100
From:   Conor Dooley <conor.dooley@...rochip.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        "Lee Jones" <lee.jones@...aro.org>
CC:     Daire McNamara <daire.mcnamara@...rochip.com>,
        <linux-kernel@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
        <linux-riscv@...ts.infradead.org>,
        Conor Dooley <conor.dooley@...rochip.com>
Subject: [PATCH v3 0/2] Add support for Microchip's pwm fpga core

Hey Uwe,
Got a ~v2~ v3 for you...
I added some comments explaining the calculations and a documentation link
so hopefully things are a bit easier to follow.

Code wise, I went through and sorted out a bunch of issues that cycling
through the different periods/duties threw up. Along the way I found
some other problems - especially with the longer periods which I have
fixed. I also added a write to the sync register in the apply function,
which will resolve to a NOP for channels without "shadow registers".

Other than that, I managed to ditch the mchp_core_pwm_registers struct
entirely but had to add a short delay before reading back the registers
in order to compute the duty.

Thanks,
Conor.

Changes from v2:
- fix percieved idempotency and rounding issues when shadow registers were
  enabled
- use do_div() for divide of u64 tmp in apply_period()

Changes from v1:
- account for edge "quirk" while inverted
- block changing enabled channels' period
- document the hardware/driver limitations
- rearrange get_state() more logically
- fix cast sizes in get_state()
- fix remove() and probe error paths
- delete mchp_core_pwm_registers
- simplify .apply() logic
- don't warn in calculate_base()
- fix period calculation
- fix duty cycle calculation
- add COREPWM prefix to defines
- add a documentation link

Conor Dooley (2):
  pwm: add microchip soft ip corePWM driver
  MAINTAINERS: add pwm to PolarFire SoC entry

 MAINTAINERS                      |   1 +
 drivers/pwm/Kconfig              |  10 +
 drivers/pwm/Makefile             |   1 +
 drivers/pwm/pwm-microchip-core.c | 325 +++++++++++++++++++++++++++++++
 4 files changed, 337 insertions(+)
 create mode 100644 drivers/pwm/pwm-microchip-core.c


base-commit: 61114e734ccb804bc12561ab4020745e02c468c2
-- 
2.36.1