Re: gpio: dwapb: Synopsys Designware GPIO

[Sebastian Hesselbarth <sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 10/31/2013 05:17 PM, Steffen Trumtrar wrote:
> On Thu, Oct 31, 2013 at 04:07:23PM +0000, Jamie Iles wrote:
>> On Thu, Oct 31, 2013 at 04:58:03PM +0100, Steffen Trumtrar wrote:
>>> I wonder if we want to really keep the binding as it is proposed by
>>> Jamie. Do we really win anything by having to specify the banks in the
>>> DT? In my version I get the number of ports, width etc. from the config registers
>>> of the device. I think everything that the device knows itself and can be read
>>> out at runtime shouldn't be specified in the DT.
>>> And it seems that the binding was never merged, so I guess we can change it.
>>
>> The reason for having it split into banks is that for hardware that has
>> a mixture of bank sizes (odd hardware admittedly, but that includes
>> hardware that I was writing the driver for), we had a setup like 16 pins
>> on bank A, 16 on B, 1 on C and 16 on D where each bank could have a
>> maximum of 32, so converting from a data sheet to GPIO number is not
>> obvious.  Grant Likely suggested representing the banks as different
>> devices, so that's how I created the binding.
>
> I have no problem with the binding, if it is worth it. Do you mean you had
> hardware where the gpio lines where not connected? Or maybe you had an older
> version of the IP core?
> In the Socfpga case there is gpio_config_reg2, which specifies the width
> for every of the 4 ports. So I thought I use those values to describe my
> hardware. The Socfpga however only uses the first bank of its three GPIO cores,
> so I wouldn't be able to test if the code works for more than just that.

Having talked with Heiko at ELCE, both upcoming mach-berlin and
mach-rockchip will be using dw-apb-gpio as GPIO driver. Unfortunately,
while berlin has the CONFIG[12] registers, rockchip has not. So there
must be bindings to at least overwrite the obvious settings derived
from that registers.

Also, IIRC Heiko prefers to use platform_data driven registration as it
is tightly coupled with rk's pinmux. So there should really be support
for that and DT parsing on top that fills platform_data.

Can you please resend the whole set on list so we can review it again
with more machs involved?

Sebastian
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