058dfc7670
Starting from Intel Skylake the iTCO watchdog timer registers were moved to reside in the same register space with SMBus host controller. Not all needed registers are available though and we need to unhide P2SB (Primary to Sideband) device briefly to be able to read status of required NO_REBOOT bit. The i2c-i801.c SMBus driver used to handle this and creation of the iTCO watchdog platform device. Windows, on the other hand, does not use the iTCO watchdog hardware directly even if it is available. Instead it relies on ACPI Watchdog Action Table (WDAT) table to describe the watchdog hardware to the OS. This table contains necessary information about the the hardware and also set of actions which are executed by a driver as needed. This patch implements a new watchdog driver that takes advantage of the ACPI WDAT table. We split the functionality into two parts: first part enumerates the WDAT table and if found, populates resources and creates platform device for the actual driver. The second part is the driver itself. The reason for the split is that this way we can make the driver itself to be a module and loaded automatically if the WDAT table is found. Otherwise the module is not loaded. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
124 lines
3 KiB
C
124 lines
3 KiB
C
/*
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* ACPI watchdog table parsing support.
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*
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* Copyright (C) 2016, Intel Corporation
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* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) "ACPI: watchdog: " fmt
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#include <linux/acpi.h>
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#include <linux/ioport.h>
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#include <linux/platform_device.h>
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#include "internal.h"
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/**
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* Returns true if this system should prefer ACPI based watchdog instead of
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* the native one (which are typically the same hardware).
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*/
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bool acpi_has_watchdog(void)
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{
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struct acpi_table_header hdr;
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if (acpi_disabled)
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return false;
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return ACPI_SUCCESS(acpi_get_table_header(ACPI_SIG_WDAT, 0, &hdr));
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}
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EXPORT_SYMBOL_GPL(acpi_has_watchdog);
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void __init acpi_watchdog_init(void)
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{
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const struct acpi_wdat_entry *entries;
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const struct acpi_table_wdat *wdat;
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struct list_head resource_list;
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struct resource_entry *rentry;
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struct platform_device *pdev;
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struct resource *resources;
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size_t nresources = 0;
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acpi_status status;
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int i;
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status = acpi_get_table(ACPI_SIG_WDAT, 0,
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(struct acpi_table_header **)&wdat);
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if (ACPI_FAILURE(status)) {
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/* It is fine if there is no WDAT */
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return;
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}
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/* Watchdog disabled by BIOS */
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if (!(wdat->flags & ACPI_WDAT_ENABLED))
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return;
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/* Skip legacy PCI WDT devices */
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if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
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wdat->pci_device != 0xff || wdat->pci_function != 0xff)
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return;
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INIT_LIST_HEAD(&resource_list);
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entries = (struct acpi_wdat_entry *)(wdat + 1);
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for (i = 0; i < wdat->entries; i++) {
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const struct acpi_generic_address *gas;
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struct resource_entry *rentry;
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struct resource res;
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bool found;
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gas = &entries[i].register_region;
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res.start = gas->address;
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if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
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res.flags = IORESOURCE_MEM;
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res.end = res.start + ALIGN(gas->access_width, 4);
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} else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
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res.flags = IORESOURCE_IO;
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res.end = res.start + gas->access_width;
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} else {
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pr_warn("Unsupported address space: %u\n",
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gas->space_id);
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goto fail_free_resource_list;
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}
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found = false;
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resource_list_for_each_entry(rentry, &resource_list) {
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if (resource_contains(rentry->res, &res)) {
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found = true;
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break;
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}
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}
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if (!found) {
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rentry = resource_list_create_entry(NULL, 0);
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if (!rentry)
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goto fail_free_resource_list;
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*rentry->res = res;
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resource_list_add_tail(rentry, &resource_list);
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nresources++;
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}
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}
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resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
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if (!resources)
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goto fail_free_resource_list;
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i = 0;
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resource_list_for_each_entry(rentry, &resource_list)
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resources[i++] = *rentry->res;
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pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
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resources, nresources);
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if (IS_ERR(pdev))
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pr_err("Failed to create platform device\n");
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kfree(resources);
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fail_free_resource_list:
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resource_list_free(&resource_list);
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}
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