# Re: \[PATCH V3 16/22\] LoongArch: Add misc common routines

- From: Christoph Hellwig \<hch@infradead.org\>
- Date: 2021-09-17 06:12:57 
- List: linux-doc
- Page: https://ratatoskr.run/linux-doc/2021/09/1512508
- Thread: https://ratatoskr.run/linux-arch/2021/09/1512437/t.md

```text
> +
> +/*
> + * Change "struct page" to physical address.
> + */
> +#define page_to_phys(page)	((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)

Why is this using a dma_addr_t?  phys_addr_t would be the right type
here.

> +
> +extern void __init __iomem *early_ioremap(u64 phys_addr, unsigned long size);
> +extern void __init early_iounmap(void __iomem *addr, unsigned long size);
> +
> +#define early_memremap early_ioremap
> +#define early_memunmap early_iounmap
> +
> +static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
> +					 unsigned long prot_val)
> +{
> +	if (prot_val == _CACHE_CC)
> +		return (void __iomem *)(unsigned long)(CAC_BASE + offset);
> +	else
> +		return (void __iomem *)(unsigned long)(UNCAC_BASE + offset);
> +}

There is no real need for this ioremap_prot multiplexer

> +/*
> + * ioremap_cache -  map bus memory into CPU space
> + * @offset:	    bus address of the memory
> + * @size:	    size of the resource to map
> + *
> + * ioremap_cache performs a platform specific sequence of operations to
> + * make bus memory CPU accessible via the readb/readw/readl/writeb/
> + * writew/writel functions and the other mmio helpers. The returned
> + * address is not guaranteed to be usable directly as a virtual
> + * address.
> + *
> + * This version of ioremap ensures that the memory is marked cachable by
> + * the CPU.  Also enables full write-combining.	 Useful for some
> + * memory-like regions on I/O busses.
> + */
> +#define ioremap_cache(offset, size)				\
> +	ioremap_prot((offset), (size), _CACHE_CC)

Please don't add ioremap_cache to new ports.
```