Hi Drew, Hi Linus,
Am 2021-07-26 09:11, schrieb Drew Fustini:
On Fri, Jul 23, 2021 at 11:04:41PM +0200, Linus Walleij wrote:
On Thu, Jul 1, 2021 at 8:39 AM Michael Walle <michael@xxxxxxxx> wrote:
> Am 2021-07-01 02:20, schrieb Drew Fustini:
> > Add GPIO driver for the StarFive JH7100 SoC [1] used on the
> > BeagleV Starlight JH7100 board [2].
> >
> > [1] https://github.com/starfive-tech/beaglev_doc/
> > [2] https://github.com/beagleboard/beaglev-starlight
> >
> > Signed-off-by: Emil Renner Berthing <kernel@xxxxxxxx>
> > Signed-off-by: Huan Feng <huan.feng@xxxxxxxxxxxxxxxx>
> > Signed-off-by: Drew Fustini <drew@xxxxxxxxxxxxxxx>
>
> Could this driver use GPIO_REGMAP and REGMAP_IRQ? See
> drivers/gpio/gpio-sl28cpld.c for an example.
To me it looks just memory-mapped?
Good old gpio-mmio.c (select GPIO_GENERIC) should
suffice I think.
But that doesn't mean gpio-regmap can't be used, no? Or what are
the advantages of gpio-mmio?
Drew please look at drivers/gpio/gpio-ftgpio010.c for an example
of GPIO_GENERIC calling bgpio_init() in probe().
Thank you for the suggestion. However, I am not sure that will work for
this SoC.
The GPIO registers are described in section 12 of JH7100 datasheet [1]
and I don't think they fit the expectation of gpio-mmio.c because there
is a seperate register for each GPIO line for output data value and
output enable.
There are 64 output data config registers which are 4 bytes wide. There
are 64 output enable config registers which are 4 bytes wide too.
Output
data and output enable registers for a given GPIO pad are contiguous.
GPIO0_DOUT_CFG is 0x50 and GPIO0_DOEN_CFG is 0x54 while GPIO1_DOUT_CFG
is 0x58 and GPIO1_DOEN_CFG is 0x5C. The stride between GPIO pads is
effectively 8, which yields the formula: GPIOn_DOUT_CFG is 0x50+8n.
Similarly, GPIO0_DOEN_CFG is 0x54 and thus GPIOn_DOEN_CFG is 0x54+8n.
However, GPIO input data does use just one bit for each line. GPIODIN_0
at 0x48 covers GPIO[31:0] and GPIODIN_1 at 0x4c covers GPIO[63:32].
I'd say, that should work with the .reg_mask_xlate of the gpio-regmap.
-michael
Thus the input could work with gpio-mmio but I am not sure how to
reconcile the register-per-gpio for the output value and output enable.
Is there way a way to adapt gpio-mmio for this situation?
Thanks,
Drew
[1] https://github.com/starfive-tech/beaglev_doc
