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lib: add iomem emulation (logic_iomem)

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Add IO memory emulation that uses callbacks for read/write to
the allocated regions. The callbacks can be registered by the
users using logic_iomem_alloc().

To use, an architecture must 'select LOGIC_IOMEM' in Kconfig
and then include <asm-generic/logic_io.h> into asm/io.h to get
the __raw_read*/__raw_write* functions.

Optionally, an architecture may 'select LOGIC_IOMEM_FALLBACK'
in which case non-emulated regions will 'fall back' to the
various real_* functions that must then be provided.

Cc: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Johannes Berg
2021-03-05 13:19:52 +01:00
committed by Richard Weinberger
parent 0bbadafdc4
commit ca2e334232
5 changed files with 474 additions and 0 deletions
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62
include/linux/logic_iomem.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2021 Intel Corporation
* Author: johannes@sipsolutions.net
*/
#ifndef __LOGIC_IOMEM_H
#define __LOGIC_IOMEM_H
#include <linux/types.h>
#include <linux/ioport.h>
/**
* struct logic_iomem_ops - emulated IO memory ops
* @read: read an 8, 16, 32 or 64 bit quantity from the given offset,
* size is given in bytes (1, 2, 4 or 8)
* (64-bit only necessary if CONFIG_64BIT is set)
* @write: write an 8, 16 32 or 64 bit quantity to the given offset,
* size is given in bytes (1, 2, 4 or 8)
* (64-bit only necessary if CONFIG_64BIT is set)
* @set: optional, for memset_io()
* @copy_from: optional, for memcpy_fromio()
* @copy_to: optional, for memcpy_toio()
* @unmap: optional, this region is getting unmapped
*/
struct logic_iomem_ops {
unsigned long (*read)(void *priv, unsigned int offset, int size);
void (*write)(void *priv, unsigned int offset, int size,
unsigned long val);
void (*set)(void *priv, unsigned int offset, u8 value, int size);
void (*copy_from)(void *priv, void *buffer, unsigned int offset,
int size);
void (*copy_to)(void *priv, unsigned int offset, const void *buffer,
int size);
void (*unmap)(void *priv);
};
/**
* struct logic_iomem_region_ops - ops for an IO memory handler
* @map: map a range in the registered IO memory region, must
* fill *ops with the ops and may fill *priv to be passed
* to the ops. The offset is given as the offset into the
* registered resource region.
* The return value is negative for errors, or >= 0 for
* success. On success, the return value is added to the
* offset for later ops, to allow for partial mappings.
*/
struct logic_iomem_region_ops {
long (*map)(unsigned long offset, size_t size,
const struct logic_iomem_ops **ops,
void **priv);
};
/**
* logic_iomem_add_region - register an IO memory region
* @resource: the resource description for this region
* @ops: the IO memory mapping ops for this resource
*/
int logic_iomem_add_region(struct resource *resource,
const struct logic_iomem_region_ops *ops);
#endif /* __LOGIC_IOMEM_H */