[PATCH] Implement ioremap_prot support (v2)

[Palmer Dabbelt]

On Fri, 02 Dec 2022 00:33:56 PST (-0800), jiangjianwen at uniontech.com wrote:
>     Feature ioremap_prot only needs an implementation of pte_pgprot on riscv.
>     That macro is similar to the same one on platform loongarch, mips and sh.
>     We just need:
>     1. replace _PFN_MASK with _PAGE_PFN_MASK in pte_gpprot;
>     2. add "select HAVE_IOREMAP_PROT" into arch/riscv/Kconfig;
>     3. add "depends on MMU" into drivers/fpga/Kconfig to fix the building error "undefined reference to generic_access_phys".

That third one should be its own patch, it's not really related to the 
RISC-V bits.

>
>     Signed-off-by: Jianwen Jiang <jiangjianwen at uniontech.com>
> ---
>  arch/riscv/Kconfig            | 1 +
>  arch/riscv/include/asm/page.h | 2 ++
>  drivers/fpga/Kconfig          | 1 +
>  3 files changed, 4 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index fa78595a6089..5ed2c7361040 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -95,6 +95,7 @@ config RISCV
>  	select HAVE_FUNCTION_ERROR_INJECTION
>  	select HAVE_GCC_PLUGINS
>  	select HAVE_GENERIC_VDSO if MMU && 64BIT
> +	select HAVE_IOREMAP_PROT
>  	select HAVE_IRQ_TIME_ACCOUNTING
>  	select HAVE_KPROBES if !XIP_KERNEL
>  	select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> index ac70b0fd9a9a..cb08a4911d60 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -84,6 +84,8 @@ typedef struct page *pgtable_t;
>  #define __pgd(x)	((pgd_t) { (x) })
>  #define __pgprot(x)	((pgprot_t) { (x) })
>
> +#define pte_pgprot(x)  __pgprot(pte_val(x) & ~_PAGE_PFN_MASK)
> +
>  #ifdef CONFIG_64BIT
>  #define PTE_FMT "%016lx"
>  #else
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index bbe0a7cabb75..0493272b8bff 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -5,6 +5,7 @@
>
>  menuconfig FPGA
>  	tristate "FPGA Configuration Framework"
> +	depends on MMU
>  	help
>  	  Say Y here if you want support for configuring FPGAs from the
>  	  kernel.  The FPGA framework adds an FPGA manager class and FPGA