/* $NetBSD: apei_mapreg.c,v 1.4 2024/03/22 20:47:52 riastradh Exp $ */

/* $NetBSD: apei_mapreg.c,v 1.4 2024/03/22 20:47:52 riastradh Exp $ */

/*-
* Copyright (c) 2024 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* Pre-mapped ACPI register access
*
* XXX This isn't APEI-specific -- it should be moved into the general
* ACPI API, and unified with the AcpiRead/AcpiWrite implementation.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: apei_mapreg.c,v 1.4 2024/03/22 20:47:52 riastradh Exp $");

#include <sys/types.h>

#include <sys/atomic.h>

#include <dev/acpi/acpivar.h>
#include <dev/acpi/apei_mapreg.h>

/*
* apei_mapreg_map(reg)
*
* Return a mapping for use with apei_mapreg_read, or NULL if it
* can't be mapped.
*/
struct apei_mapreg *
apei_mapreg_map(const ACPI_GENERIC_ADDRESS *reg)
{

/*
* Verify the result is reasonable.
*/
switch (reg->BitWidth) {
case 8:
case 16:
case 32:
case 64:
break;
default:
return NULL;
}

/*
* Verify we know how to do the access width.
*/
switch (reg->AccessWidth) {
case 1: /* 8-bit */
case 2: /* 16-bit */
case 3: /* 32-bit */
break;
case 4: /* 64-bit */
if (reg->SpaceId == ACPI_ADR_SPACE_SYSTEM_IO)
return NULL;
break;
default:
return NULL;
}

/*
* Verify we don't need to shift anything, because I can't
* figure out how the shifting is supposed to work in five
* minutes of looking at the spec.
*/
switch (reg->BitOffset) {
case 0:
break;
default:
return NULL;
}

/*
* Verify the bit width is a multiple of the access width so
* we're not accessing more than we need.
*/
if (reg->BitWidth % (8*(1 << (reg->AccessWidth - 1))))
return NULL;

/*
* Dispatch on the space id.
*/
switch (reg->SpaceId) {
case ACPI_ADR_SPACE_SYSTEM_IO:
/*
* Just need to return something non-null -- no state
* to record for a mapping.
*/
return (struct apei_mapreg *)__UNCONST(reg);
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
return AcpiOsMapMemory(reg->Address,
1 << (reg->AccessWidth - 1));
default:
return NULL;
}
}

/*
* apei_mapreg_unmap(reg, map)
*
* Unmap a mapping previously returned by apei_mapreg_map.
*/
void
apei_mapreg_unmap(const ACPI_GENERIC_ADDRESS *reg,
struct apei_mapreg *map)
{

switch (reg->SpaceId) {
case ACPI_ADR_SPACE_SYSTEM_IO:
KASSERT(map == __UNCONST(reg));
break;
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
AcpiOsUnmapMemory(map, 1 << (reg->AccessWidth - 1));
break;
default:
panic("invalid register mapping");
}
}

/*
* apei_mapreg_read(reg, map)
*
* Read from reg via map previously obtained by apei_mapreg_map.
*/
uint64_t
apei_mapreg_read(const ACPI_GENERIC_ADDRESS *reg,
const struct apei_mapreg *map)
{
unsigned chunkbits = NBBY*(1 << (reg->AccessWidth - 1));
unsigned i, n = reg->BitWidth / chunkbits;
uint64_t v = 0;

for (i = 0; i < n; i++) {
uint64_t chunk;

switch (reg->SpaceId) {
case ACPI_ADR_SPACE_SYSTEM_IO: {
ACPI_IO_ADDRESS addr;
uint32_t chunk32 = 0;
ACPI_STATUS rv;

switch (reg->AccessWidth) {
case 1:
addr = reg->Address + i;
break;
case 2:
addr = reg->Address + 2*i;
break;
case 3:
addr = reg->Address + 4*i;
break;
case 4: /* no 64-bit I/O ports */
default:
__unreachable();
}
rv = AcpiOsReadPort(addr, &chunk32,
NBBY*(1 << (reg->AccessWidth - 1)));
KASSERTMSG(!ACPI_FAILURE(rv), "%s",
AcpiFormatException(rv));
chunk = chunk32;
break;
}
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
switch (reg->AccessWidth) {
case 1:
chunk = *((volatile const uint8_t *)map + i);
break;
case 2:
chunk = *((volatile const uint16_t *)map + i);
break;
case 3:
chunk = *((volatile const uint32_t *)map + i);
break;
case 4:
chunk = *((volatile const uint64_t *)map + i);
break;
default:
__unreachable();
}
break;
default:
__unreachable();
}
v |= chunk << (i*chunkbits);
}

membar_acquire(); /* XXX probably not right for MMIO */
return v;
}

/*
* apei_mapreg_write(reg, map, v)
*
* Write to reg via map previously obtained by apei_mapreg_map.
*/
void
apei_mapreg_write(const ACPI_GENERIC_ADDRESS *reg, struct apei_mapreg *map,
uint64_t v)
{
unsigned chunkbits = NBBY*(1 << (reg->AccessWidth - 1));
unsigned i, n = reg->BitWidth / chunkbits;

membar_release(); /* XXX probably not right for MMIO */
for (i = 0; i < n; i++) {
uint64_t chunk = v >> (i*chunkbits);

switch (reg->SpaceId) {
case ACPI_ADR_SPACE_SYSTEM_IO: {
ACPI_IO_ADDRESS addr;
ACPI_STATUS rv;

switch (reg->AccessWidth) {
case 1:
addr = reg->Address + i;
break;
case 2:
addr = reg->Address + 2*i;
break;
case 3:
addr = reg->Address + 4*i;
break;
case 4: /* no 64-bit I/O ports */
default:
__unreachable();
}
rv = AcpiOsWritePort(addr, chunk,
NBBY*(1 << (reg->AccessWidth - 1)));
KASSERTMSG(!ACPI_FAILURE(rv), "%s",
AcpiFormatException(rv));
break;
}
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
switch (reg->AccessWidth) {
case 1:
*((volatile uint8_t *)map + i) = chunk;
break;
case 2:
*((volatile uint16_t *)map + i) = chunk;
break;
case 3:
*((volatile uint32_t *)map + i) = chunk;
break;
case 4:
*((volatile uint64_t *)map + i) = chunk;
break;
default:
__unreachable();
}
break;
default:
__unreachable();
}
}
}