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

[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)

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