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SubjectRe: [PATCH] spi: Updated PXA2xx SSP SPI Driver
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On Fri, 2006-02-10 at 12:40 -0500, Nicolas Pitre wrote:
> [...]
>
> +#define SSP_REG(x) (*((volatile unsigned long *)x))
>
> Don't do that. Instead, please use:
>
> #define DEFINE_SSP_REG(reg, off) \
> static inline u32 read_##reg(void *p) { return __raw_readl(p + (off)); \
> static inline void write_##reg(u32 v, void *p) { __raw_writel(v, p + (off)); }
>
> DEFINE_SSP_REG(SSCR0, 0x00)
> DEFINE_SSP_REG(SSCR1, 0x04)
> DEFINE_SSP_REG(SSSR, 0x08)
> DEFINE_SSP_REG(SSITR, 0x0c)
> DEFINE_SSP_REG(SSDR, 0x10)
> DEFINE_SSP_REG(SSTO, 0x28)
> DEFINE_SSP_REG(SSPSP, 0x2c)
>
Ok, I'll do this (Andrew made a similar comment). But...

I modeled my SSP_REG on the contents of include/asm-
arm/arch_pxa/pxa_reg.h which makes extensive use of __REG defined in
include/asm-arm/arch_pxa/hardware.h as

#define __REG(x) (*((volatile u32 *)io_p2v(x)))

which is effectively my SSP_REG without the io_p2v because I preloaded
the virtual SSP register addresses in the pxa2xx_spi_probe function.

For my education:

Why are __raw_readl and friends better than exploiting the memory map
I/O nature of the PXA2xx and other SOCs?

Especially since something like

SSP_REG(sscr1) &= ~SSCR1_TIE;

becomes

write_SSCR1(read_SSCR1(reg) & ~SSCR_TIE, reg);

Further what should I do with the DMA register accesses (i.e. DCSR,
DCMD, etc)?

> +static void dma_handler(int channel, void *data, struct pt_regs *regs)
> +{
> + struct driver_data *drv_data = (struct driver_data *)data;
> + struct spi_message *msg = drv_data->cur_msg;
> + u32 sssr = drv_data->sssr;
> + u32 sscr1 = drv_data->sscr1;
> + u32 ssto = drv_data->sscr1;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^
>
Definitely wrong, harmless in this case but bad none the less. Thanks
great eyes!

Stephen



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