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Subject: Re: [PATCH v2 2/2] pwm: Add support for Xilinx AXI Timer
To:     Sean Anderson <sean.anderson@seco.com>,
        <linux-pwm@vger.kernel.org>, <devicetree@vger.kernel.org>
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References: <20210504184925.3399934-1-sean.anderson@seco.com>
 <20210504184925.3399934-2-sean.anderson@seco.com>
From:   Michal Simek <michal.simek@xilinx.com>
Message-ID: <e3782bc5-bcd9-5eb8-e89b-e4e52ed2e3cb@xilinx.com>
Date:   Wed, 5 May 2021 08:37:59 +0200
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On 5/4/21 8:49 PM, Sean Anderson wrote:
> This adds PWM support for Xilinx LogiCORE IP AXI soft timers commonly
> found on Xilinx FPGAs. There is another driver for this device located
> at arch/microblaze/kernel/timer.c, but it is only used for timekeeping.
> This driver was written with reference to Xilinx DS764 for v1.03.a [1].
> 
> [1] https://www.xilinx.com/support/documentation/ip_documentation/axi_timer/v1_03_a/axi_timer_ds764.pdf
> 
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---
> I tried adding a XILINX_PWM_ prefix to all the defines, but IMO it
> really hurt readability. That prefix almost doubles the size the
> defines, and is particularly excessive in something like
> XILINX_PWM_TCSR_RUN_MASK.
> 
> Changes in v2:
> - Don't compile this module by default for arm64
> - Add dependencies on COMMON_CLK and HAS_IOMEM
> - Add comment explaining why we depend on !MICROBLAZE
> - Add comment describing device
> - Rename TCSR_(SET|CLEAR) to TCSR_RUN_(SET|CLEAR)
> - Use NSEC_TO_SEC instead of defining our own
> - Use TCSR_RUN_MASK to check if the PWM is enabled, as suggested by Uwe
> - Cast dividends to u64 to avoid overflow
> - Check for over- and underflow when calculating TLR
> - Set xilinx_pwm_ops.owner
> - Don't set pwmchip.base to -1
> - Check range of xlnx,count-width
> - Ensure the clock is always running when the pwm is registered
> - Remove debugfs file :l
> - Report errors with dev_error_probe
> 
>  drivers/pwm/Kconfig      |  13 ++
>  drivers/pwm/Makefile     |   1 +
>  drivers/pwm/pwm-xilinx.c | 301 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 315 insertions(+)
>  create mode 100644 drivers/pwm/pwm-xilinx.c

Without looking below another driver which target the same IP is just
wrong that's why NACK from me.

Thanks,
Michal