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/*
* ACPI watchdog table parsing support.
*
* Copyright (C) 2016, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define pr_fmt(fmt) "ACPI: watchdog: " fmt
#include <linux/acpi.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include "internal.h"
#ifdef CONFIG_RTC_MC146818_LIB
#include <linux/mc146818rtc.h>
/*
* There are several systems where the WDAT table is accessing RTC SRAM to
* store persistent information. This does not work well with the Linux RTC
* driver so on those systems we skip WDAT driver and prefer iTCO_wdt
* instead.
*
* See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.
*/
static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
{
const struct acpi_wdat_entry *entries;
int i;
entries = (struct acpi_wdat_entry *)(wdat + 1);
for (i = 0; i < wdat->entries; i++) {
const struct acpi_generic_address *gas;
gas = &entries[i].register_region;
if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
switch (gas->address) {
case RTC_PORT(0):
case RTC_PORT(1):
case RTC_PORT(2):
case RTC_PORT(3):
return true;
}
}
}
return false;
}
#else
static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
{
return false;
}
#endif
static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
{
const struct acpi_table_wdat *wdat = NULL;
acpi_status status;
if (acpi_disabled)
return NULL;
status = acpi_get_table(ACPI_SIG_WDAT, 0,
(struct acpi_table_header **)&wdat);
if (ACPI_FAILURE(status)) {
/* It is fine if there is no WDAT */
return NULL;
}
if (acpi_watchdog_uses_rtc(wdat)) {
pr_info("Skipping WDAT on this system because it uses RTC SRAM\n");
return NULL;
}
return wdat;
}
/**
* Returns true if this system should prefer ACPI based watchdog instead of
* the native one (which are typically the same hardware).
*/
bool acpi_has_watchdog(void)
{
return !!acpi_watchdog_get_wdat();
}
EXPORT_SYMBOL_GPL(acpi_has_watchdog);
void __init acpi_watchdog_init(void)
{
const struct acpi_wdat_entry *entries;
const struct acpi_table_wdat *wdat;
struct list_head resource_list;
struct resource_entry *rentry;
struct platform_device *pdev;
struct resource *resources;
size_t nresources = 0;
int i;
wdat = acpi_watchdog_get_wdat();
if (!wdat) {
/* It is fine if there is no WDAT */
return;
}
/* Watchdog disabled by BIOS */
if (!(wdat->flags & ACPI_WDAT_ENABLED))
return;
/* Skip legacy PCI WDT devices */
if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
wdat->pci_device != 0xff || wdat->pci_function != 0xff)
return;
INIT_LIST_HEAD(&resource_list);
entries = (struct acpi_wdat_entry *)(wdat + 1);
for (i = 0; i < wdat->entries; i++) {
const struct acpi_generic_address *gas;
struct resource_entry *rentry;
struct resource res = {};
bool found;
gas = &entries[i].register_region;
res.start = gas->address;
if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
res.flags = IORESOURCE_MEM;
res.end = res.start + ALIGN(gas->access_width, 4) - 1;
} else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
res.flags = IORESOURCE_IO;
res.end = res.start + gas->access_width - 1;
} else {
pr_warn("Unsupported address space: %u\n",
gas->space_id);
goto fail_free_resource_list;
}
found = false;
resource_list_for_each_entry(rentry, &resource_list) {
if (rentry->res->flags == res.flags &&
resource_overlaps(rentry->res, &res)) {
if (res.start < rentry->res->start)
rentry->res->start = res.start;
if (res.end > rentry->res->end)
rentry->res->end = res.end;
found = true;
break;
}
}
if (!found) {
rentry = resource_list_create_entry(NULL, 0);
if (!rentry)
goto fail_free_resource_list;
*rentry->res = res;
resource_list_add_tail(rentry, &resource_list);
nresources++;
}
}
resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
if (!resources)
goto fail_free_resource_list;
i = 0;
resource_list_for_each_entry(rentry, &resource_list)
resources[i++] = *rentry->res;
pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
resources, nresources);
if (IS_ERR(pdev))
pr_err("Device creation failed: %ld\n", PTR_ERR(pdev));
kfree(resources);
fail_free_resource_list:
resource_list_free(&resource_list);
}
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