Commit 8b19e145 authored by Halil Pasic's avatar Halil Pasic Committed by Heiko Carstens
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s390/cio: introduce bitwise dma types and helper functions 



Introduce dma32_t and dma64_t bitwise types, which are supposed to be used
for 31 and 64 bit DMA capable addresses. This allows to use sparse (make
C=1) for type checking, so that incorrect usages can be easily found.

Also add a couple of helper functions which
- convert virtual to DMA addresses and vice versa
- allow for simple logical and arithmetic operations on DMA addresses
- convert DMA addresses to plain u32 and u64 values

All helper functions exist to avoid excessive casting in C code.

Signed-off-by: default avatarHalil Pasic <pasic@linux.ibm.com>
Co-developed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Reviewed-by: default avatarSteffen Maier <maier@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 1c2be70e

arch/s390/include/asm/dma-types.h

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+103 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#ifndef _ASM_S390_DMA_TYPES_H_

#define _ASM_S390_DMA_TYPES_H_



#include <linux/types.h>

#include <linux/io.h>



/*

 * typedef dma32_t

 * Contains a 31 bit absolute address to a DMA capable piece of storage.

 *

 * For CIO, DMA addresses are always absolute addresses. These addresses tend

 * to be used in architectured memory blocks (like ORB, IDAW, MIDAW). Under

 * certain circumstances 31 bit wide addresses must be used because the

 * address must fit in 31 bits.

 *

 * This type is to be used when such fields can be modelled as 32 bit wide.

 */

typedef u32 __bitwise dma32_t;



/*

 * typedef dma64_t

 * Contains a 64 bit absolute address to a DMA capable piece of storage.

 *

 * For CIO, DMA addresses are always absolute addresses. These addresses tend

 * to be used in architectured memory blocks (like ORB, IDAW, MIDAW).

 *

 * This type is to be used to model such 64 bit wide fields.

 */

typedef u64 __bitwise dma64_t;



/*

 * Although DMA addresses should be obtained using the DMA API, in cases when

 * it is known that the first argument holds a virtual address that points to

 * DMA-able 31 bit addressable storage, then this function can be safely used.

 */

static inline dma32_t virt_to_dma32(void *ptr)

{

	return (__force dma32_t)__pa(ptr);

}



static inline void *dma32_to_virt(dma32_t addr)

{

	return __va((__force unsigned long)addr);

}



static inline dma32_t u32_to_dma32(u32 addr)

{

	return (__force dma32_t)addr;

}



static inline u32 dma32_to_u32(dma32_t addr)

{

	return (__force u32)addr;

}



static inline dma32_t dma32_add(dma32_t a, u32 b)

{

	return (__force dma32_t)((__force u32)a + b);

}



static inline dma32_t dma32_and(dma32_t a, u32 b)

{

	return (__force dma32_t)((__force u32)a & b);

}



/*

 * Although DMA addresses should be obtained using the DMA API, in cases when

 * it is known that the first argument holds a virtual address that points to

 * DMA-able storage, then this function can be safely used.

 */

static inline dma64_t virt_to_dma64(void *ptr)

{

	return (__force dma64_t)__pa(ptr);

}



static inline void *dma64_to_virt(dma64_t addr)

{

	return __va((__force unsigned long)addr);

}



static inline dma64_t u64_to_dma64(u64 addr)

{

	return (__force dma64_t)addr;

}



static inline u64 dma64_to_u64(dma64_t addr)

{

	return (__force u64)addr;

}



static inline dma64_t dma64_add(dma64_t a, u64 b)

{

	return (__force dma64_t)((__force u64)a + b);

}



static inline dma64_t dma64_and(dma64_t a, u64 b)

{

	return (__force dma64_t)((__force u64)a & b);

}



#endif /* _ASM_S390_DMA_TYPES_H_ */