Hi Adrian,
CC dt
On Wed, May 3, 2023 at 10:14 AM John Paul Adrian Glaubitz
<glaubitz@xxxxxxxxxxxxxxxxxxx> wrote:
> When building j2_defconfig, the following warning is issued:
>
> arch/sh/kernel/cpu/sh2/probe.c: In function 'scan_cache':
> arch/sh/kernel/cpu/sh2/probe.c:24:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
> 24 | j2_ccr_base = (u32 __iomem *)of_flat_dt_translate_address(node);
> |
>
> Reading the code and look how other users of of_flat_dt_translate_address()
> used the return code, I came up with the following patch which fixes the issue:
>
> diff --git a/arch/sh/kernel/cpu/sh2/probe.c b/arch/sh/kernel/cpu/sh2/probe.c
> index d342ea08843f..a0dc3675fc68 100644
> --- a/arch/sh/kernel/cpu/sh2/probe.c
> +++ b/arch/sh/kernel/cpu/sh2/probe.c
> @@ -14,14 +14,14 @@
> #include <asm/cache.h>
>
> #if defined(CONFIG_CPU_J2)
> -extern u32 __iomem *j2_ccr_base;
> +extern phys_addr_t j2_ccr_base;
> static int __init scan_cache(unsigned long node, const char *uname,
> int depth, void *data)
> {
> if (!of_flat_dt_is_compatible(node, "jcore,cache"))
> return 0;
>
> - j2_ccr_base = (u32 __iomem *)of_flat_dt_translate_address(node);
> + j2_ccr_base = of_flat_dt_translate_address(node);
of_flat_dt_translate_address() indeed returns a CPU physical address
(perhaps its return type should be changed from u64 to phys_addr_t?)...
>
> return 1;
> }
> diff --git a/arch/sh/mm/cache-j2.c b/arch/sh/mm/cache-j2.c
> index f277862a11f5..2bc6d38d6f7c 100644
> --- a/arch/sh/mm/cache-j2.c
> +++ b/arch/sh/mm/cache-j2.c
> @@ -22,7 +22,7 @@
> #define DCACHE_FLUSH 0x200
> #define CACHE_FLUSH (ICACHE_FLUSH | DCACHE_FLUSH)
>
> -u32 __iomem *j2_ccr_base;
> +phys_addr_t j2_ccr_base;
... however, all other users of j2_ccr_base use this with __raw_*()
I/O accessors, so "u32 __iomem *" is correct.
What is missing is a proper conversion from physical to virtual
addresses, using e.g. ioremap().
As this is nommu, the identity mapping in ioremap() in
arch/sh/include/asm/io.h should do, and cannot fail.
So just:
j2_ccr_base = ioremap(of_flat_dt_translate_address(node), 4);
should be fine.
BTW, "jcore,cache" does not have any DT binding documentation.
>
> static void j2_flush_icache(void *args)
> {
>
> Does that look reasonable?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
