Re: [PATCH v2 0/5] clk: lpc32xx: add clock support for NXP LPC32xx

Michael Turquette
2015-12-24T20:37:19Z

On 12/21, Vladimir Zapolskiy wrote:
> Hi Stephen, Michael,
>
> On 06.12.2015 12:45, Vladimir Zapolskiy wrote:
> > This changeset adds common clock framework driver for NXP LPC32xx
> > boards.
> >
> > The change can be applied without any dependencies, LPC32xx device tree
> > and mach changes will be done, when this changeset is accepted.
> >
> > The v1 version of CCF driver can be found here:
> > http://www.spinics.net/lists/arm-kernel/msg461632.html
> >
> > The RFC version of CCF driver 9/11 can be found here:
> > http://www.spinics.net/lists/devicetree/msg100583.html
> >
> > Changes from v1 to v2:
> > * removed dependency on the recent LPC32xx device tree changes,
> > also removed LPC32xx device tree and mach changes, which depend
> > on this series,
> > * use lowercase hex numbers in a DT binding example,
> > * incremented by 1 all clock values, possibly clock "0" may have a
> > special meaning in future,
> > * removed explicit COMMON_CLK selection for NXP LPC18xx,
> > * LPC32XX_CLK_DEFINE() does not stringify clock names,
> > * fixed a minor bug in clk_pll_set_rate().
> >
> > Changes from RFC to v1:
> > * added definitions of a missed IRDA clock,
> > * renamed compatible property from lpc32xx-scb to lpc32xx-clk
> > * switched to regmap interface instead of mmio, this is required to
> > secure access to registers shared between pinmux, dma and clock
> > driver, unfortunately this change has to pull some code snippets
> > from common gate, divider and mux helpers rebased on regmap API,
> > * split clock definitions from the driver to be able to update
> > dts files separately from CCF driver.
> >
> > The driver is written from scratch, here are main functional
> > differences with the legacy driver arch/arm/mach-lpc32xx/clock.c:
> > * serialized access to SCB registers,
> > * reworked routines to select PLL parameters,
> > * now the clock driver has detailed description of all clocks,
> > the original driver misses several clock entries and most of fine
> > grained clock controls, here every mux and divider are accounted,
> > * now clocks and clock hierarchies can be described in board DT file,
> > * sophisticated management of USB clocks, for example now USB device
> > controller needs only one clock instead of USB PLL, USB OTG and USB
> > device clocks,
> > * other benefits from a driver powered by CCF.
> >
> > Patch 5/5 may produce false positives from checkpatch.pl, the fix
> > to checkpatch is found in Andrew's tree
> >
> > Vladimir Zapolskiy (5):
> > dt-bindings: clock: add description of LPC32xx clock controller
> > dt-bindings: clock: add description of LPC32xx USB clock controller
> > dt-bindings: clock: add NXP LPC32xx clock list for consumers
> > clk: lpc18xx: add NXP specific COMMON_CLK_NXP configuration symbol
> > clk: lpc32xx: add common clock framework driver
> >
> > .../devicetree/bindings/clock/nxp,lpc3220-clk.txt | 30 +
> > .../bindings/clock/nxp,lpc3220-usb-clk.txt | 22 +
> > drivers/clk/Kconfig | 6 +
> > drivers/clk/Makefile | 2 +-
> > drivers/clk/nxp/Makefile | 1 +
> > drivers/clk/nxp/clk-lpc32xx.c | 1569 ++++++++++++++++++++
> > include/dt-bindings/clock/lpc32xx-clock.h | 56 +
> > 7 files changed, 1685 insertions(+), 1 deletion(-)
> > create mode 100644 Documentation/devicetree/bindings/clock/nxp,lpc3220-clk.txt
> > create mode 100644 Documentation/devicetree/bindings/clock/nxp,lpc3220-usb-clk.txt
> > create mode 100644 drivers/clk/nxp/clk-lpc32xx.c
> > create mode 100644 include/dt-bindings/clock/lpc32xx-clock.h
> >
>
> this is a gentle ping, the first version of the driver was published
> in October, the only functional change is switching from iomap to regmap
> API to access the registers.
>
> A couple of words about the change to mitigate your impression of
> apparently imperfect code.
>
> The NXP LPC32xx platform is unmaintained and broken for about one
> and a half years, so I presume you won't get an ack from Roland, who
> is an official maintainer. Adding a CCF driver will be a huge progress,
> since it allows in +1 kernel release to fix the platform -- there is
> a critical problem in legacy IRQ handling based on hardware IRQs,
> irqchip driver change is ready as well, but CCF should go first,
> because it allows to remove a legacy clocksource/clockevent driver
> arch/arm/mach-lpc32xx/timer.c. That driver depends on legacy broken
> irqchip (hardware IRQs are used, irqchip with virtual IRQs will break
> the driver), it has a proper replacement drivers/clocksource/time-lpc32xx.c,
> but to use the new driver common clock support is needed. The CCF
> driver will let me remove tons of other legacy stuff as well, and this
> should be a step towards inclusion of the platform to multiarch builds.
>
> If you find impossible to include this CCF driver to v4.5, please add
> the first 4 of 5 changes, dt bindings include file is needed to
> update DTS files independently on CCF driver inclusion status.

Thanks for the helpful background information.

Applied to clk-next towards 4.5.

Regards,
Mike

>
> Thank you in advance.
>
> Merry Christmas, Happy Holidays!
>
> --
> With best wishes,
> Vladimir