Re: How to add support to different reg offset definition to share the same driver code?

[Jun Nie <jun.nie@linaro.org>]

2017-06-30 19:01 GMT+08:00 Leif Lindholm <leif.lindholm@linaro.org>:
> Hi Jun,
>
> I think there is more than one benefit in mimicing the Linux driver,
> so I would lean towards the Pcd option. But as Ard points out to me,
> it needs to use a FixedPcd (using FixedPcdGet()) - this can only ever
> have a buildtime resolution.
>
> Regards,
>
> Leif (technically on holiday, so no patch review until Monday)


Just learn from Liming that a MACRO is OK to control the register
offset definition in header file as we can change build option in
platform.dsc file. This should be most clear method to minimize impact
to other platform.

Jun

>
> On Fri, Jun 30, 2017 at 11:35:26AM +0800, Jun Nie wrote:
>> Hi,
>>
>> I am trying to add support to different reg offset and bit offset in
>> PL011 UART. It seems impossible to add macro in platform.dsc to enable
>> undef/redef in the header file with "#ifdef ZX_PL011_FLAG". Is there
>> any proper way to control the reg/bit offset definition? Or we have to
>> adopt the Linux driver method with a structure to hold different
>> offset value and wrap register access function as below? If so,
>> another Pcd is needed to specify the offset structure index for the
>> platforms.
>>
>>
>> static u16 pl011_st_offsets[REG_ARRAY_SIZE] = {
>> [REG_DR] = UART01x_DR,
>> [REG_ST_DMAWM] = ST_UART011_DMAWM,
>> [REG_ST_TIMEOUT] = ST_UART011_TIMEOUT,
>>         ...
>> }
>>
>> static unsigned int pl011_read(const struct uart_amba_port *uap,
>> unsigned int reg)
>> {
>> void __iomem *addr = uap->port.membase + uap->reg_offset[reg];
>>
>> return (uap->port.iotype == UPIO_MEM32) ?
>> readl_relaxed(addr) : readw_relaxed(addr);
>> }
>>
>> Jun