linux/arch/powerpc/platforms/pseries/io_event_irq.c
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   1/*
   2 * Copyright 2010 2011 Mark Nelson and Tseng-Hui (Frank) Lin, IBM Corporation
   3 *
   4 *  This program is free software; you can redistribute it and/or
   5 *  modify it under the terms of the GNU General Public License
   6 *  as published by the Free Software Foundation; either version
   7 *  2 of the License, or (at your option) any later version.
   8 */
   9
  10#include <linux/errno.h>
  11#include <linux/slab.h>
  12#include <linux/export.h>
  13#include <linux/irq.h>
  14#include <linux/interrupt.h>
  15#include <linux/of.h>
  16#include <linux/list.h>
  17#include <linux/notifier.h>
  18
  19#include <asm/machdep.h>
  20#include <asm/rtas.h>
  21#include <asm/irq.h>
  22#include <asm/io_event_irq.h>
  23
  24#include "pseries.h"
  25
  26/*
  27 * IO event interrupt is a mechanism provided by RTAS to return
  28 * information about hardware error and non-error events. Device
  29 * drivers can register their event handlers to receive events.
  30 * Device drivers are expected to use atomic_notifier_chain_register()
  31 * and atomic_notifier_chain_unregister() to register and unregister
  32 * their event handlers. Since multiple IO event types and scopes
  33 * share an IO event interrupt, the event handlers are called one
  34 * by one until the IO event is claimed by one of the handlers.
  35 * The event handlers are expected to return NOTIFY_OK if the
  36 * event is handled by the event handler or NOTIFY_DONE if the
  37 * event does not belong to the handler.
  38 *
  39 * Usage:
  40 *
  41 * Notifier function:
  42 * #include <asm/io_event_irq.h>
  43 * int event_handler(struct notifier_block *nb, unsigned long val, void *data) {
  44 *      p = (struct pseries_io_event_sect_data *) data;
  45 *      if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE;
  46 *              :
  47 *              :
  48 *      return NOTIFY_OK;
  49 * }
  50 * struct notifier_block event_nb = {
  51 *      .notifier_call = event_handler,
  52 * }
  53 *
  54 * Registration:
  55 * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb);
  56 *
  57 * Unregistration:
  58 * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb);
  59 */
  60
  61ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
  62EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
  63
  64static int ioei_check_exception_token;
  65
  66/* pSeries event log format */
  67
  68/* Two bytes ASCII section IDs */
  69#define PSERIES_ELOG_SECT_ID_PRIV_HDR           (('P' << 8) | 'H')
  70#define PSERIES_ELOG_SECT_ID_USER_HDR           (('U' << 8) | 'H')
  71#define PSERIES_ELOG_SECT_ID_PRIMARY_SRC        (('P' << 8) | 'S')
  72#define PSERIES_ELOG_SECT_ID_EXTENDED_UH        (('E' << 8) | 'H')
  73#define PSERIES_ELOG_SECT_ID_FAILING_MTMS       (('M' << 8) | 'T')
  74#define PSERIES_ELOG_SECT_ID_SECONDARY_SRC      (('S' << 8) | 'S')
  75#define PSERIES_ELOG_SECT_ID_DUMP_LOCATOR       (('D' << 8) | 'H')
  76#define PSERIES_ELOG_SECT_ID_FW_ERROR           (('S' << 8) | 'W')
  77#define PSERIES_ELOG_SECT_ID_IMPACT_PART_ID     (('L' << 8) | 'P')
  78#define PSERIES_ELOG_SECT_ID_LOGIC_RESOURCE_ID  (('L' << 8) | 'R')
  79#define PSERIES_ELOG_SECT_ID_HMC_ID             (('H' << 8) | 'M')
  80#define PSERIES_ELOG_SECT_ID_EPOW               (('E' << 8) | 'P')
  81#define PSERIES_ELOG_SECT_ID_IO_EVENT           (('I' << 8) | 'E')
  82#define PSERIES_ELOG_SECT_ID_MANUFACT_INFO      (('M' << 8) | 'I')
  83#define PSERIES_ELOG_SECT_ID_CALL_HOME          (('C' << 8) | 'H')
  84#define PSERIES_ELOG_SECT_ID_USER_DEF           (('U' << 8) | 'D')
  85
  86/* Vendor specific Platform Event Log Format, Version 6, section header */
  87struct pseries_elog_section {
  88        uint16_t id;                    /* 0x00 2-byte ASCII section ID */
  89        uint16_t length;                /* 0x02 Section length in bytes */
  90        uint8_t version;                /* 0x04 Section version         */
  91        uint8_t subtype;                /* 0x05 Section subtype         */
  92        uint16_t creator_component;     /* 0x06 Creator component ID    */
  93        uint8_t data[];                 /* 0x08 Start of section data   */
  94};
  95
  96static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
  97
  98/**
  99 * Find data portion of a specific section in RTAS extended event log.
 100 * @elog: RTAS error/event log.
 101 * @sect_id: secsion ID.
 102 *
 103 * Return:
 104 *      pointer to the section data of the specified section
 105 *      NULL if not found
 106 */
 107static struct pseries_elog_section *find_xelog_section(struct rtas_error_log *elog,
 108                                                       uint16_t sect_id)
 109{
 110        struct rtas_ext_event_log_v6 *xelog =
 111                (struct rtas_ext_event_log_v6 *) elog->buffer;
 112        struct pseries_elog_section *sect;
 113        unsigned char *p, *log_end;
 114
 115        /* Check that we understand the format */
 116        if (elog->extended_log_length < sizeof(struct rtas_ext_event_log_v6) ||
 117            xelog->log_format != RTAS_V6EXT_LOG_FORMAT_EVENT_LOG ||
 118            xelog->company_id != RTAS_V6EXT_COMPANY_ID_IBM)
 119                return NULL;
 120
 121        log_end = elog->buffer + elog->extended_log_length;
 122        p = xelog->vendor_log;
 123        while (p < log_end) {
 124                sect = (struct pseries_elog_section *)p;
 125                if (sect->id == sect_id)
 126                        return sect;
 127                p += sect->length;
 128        }
 129        return NULL;
 130}
 131
 132/**
 133 * Find the data portion of an IO Event section from event log.
 134 * @elog: RTAS error/event log.
 135 *
 136 * Return:
 137 *      pointer to a valid IO event section data. NULL if not found.
 138 */
 139static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog)
 140{
 141        struct pseries_elog_section *sect;
 142
 143        /* We should only ever get called for io-event interrupts, but if
 144         * we do get called for another type then something went wrong so
 145         * make some noise about it.
 146         * RTAS_TYPE_IO only exists in extended event log version 6 or later.
 147         * No need to check event log version.
 148         */
 149        if (unlikely(elog->type != RTAS_TYPE_IO)) {
 150                printk_once(KERN_WARNING "io_event_irq: Unexpected event type %d",
 151                            elog->type);
 152                return NULL;
 153        }
 154
 155        sect = find_xelog_section(elog, PSERIES_ELOG_SECT_ID_IO_EVENT);
 156        if (unlikely(!sect)) {
 157                printk_once(KERN_WARNING "io_event_irq: RTAS extended event "
 158                            "log does not contain an IO Event section. "
 159                            "Could be a bug in system firmware!\n");
 160                return NULL;
 161        }
 162        return (struct pseries_io_event *) &sect->data;
 163}
 164
 165/*
 166 * PAPR:
 167 * - check-exception returns the first found error or event and clear that
 168 *   error or event so it is reported once.
 169 * - Each interrupt returns one event. If a plateform chooses to report
 170 *   multiple events through a single interrupt, it must ensure that the
 171 *   interrupt remains asserted until check-exception has been used to
 172 *   process all out-standing events for that interrupt.
 173 *
 174 * Implementation notes:
 175 * - Events must be processed in the order they are returned. Hence,
 176 *   sequential in nature.
 177 * - The owner of an event is determined by combinations of scope,
 178 *   event type, and sub-type. There is no easy way to pre-sort clients
 179 *   by scope or event type alone. For example, Torrent ISR route change
 180 *   event is reported with scope 0x00 (Not Applicatable) rather than
 181 *   0x3B (Torrent-hub). It is better to let the clients to identify
 182 *   who owns the the event.
 183 */
 184
 185static irqreturn_t ioei_interrupt(int irq, void *dev_id)
 186{
 187        struct pseries_io_event *event;
 188        int rtas_rc;
 189
 190        for (;;) {
 191                rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL,
 192                                    RTAS_VECTOR_EXTERNAL_INTERRUPT,
 193                                    virq_to_hw(irq),
 194                                    RTAS_IO_EVENTS, 1 /* Time Critical */,
 195                                    __pa(ioei_rtas_buf),
 196                                    RTAS_DATA_BUF_SIZE);
 197                if (rtas_rc != 0)
 198                        break;
 199
 200                event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf);
 201                if (!event)
 202                        continue;
 203
 204                atomic_notifier_call_chain(&pseries_ioei_notifier_list,
 205                                           0, event);
 206        }
 207        return IRQ_HANDLED;
 208}
 209
 210static int __init ioei_init(void)
 211{
 212        struct device_node *np;
 213
 214        ioei_check_exception_token = rtas_token("check-exception");
 215        if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE)
 216                return -ENODEV;
 217
 218        np = of_find_node_by_path("/event-sources/ibm,io-events");
 219        if (np) {
 220                request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT");
 221                pr_info("IBM I/O event interrupts enabled\n");
 222                of_node_put(np);
 223        } else {
 224                return -ENODEV;
 225        }
 226        return 0;
 227}
 228machine_subsys_initcall(pseries, ioei_init);
 229
 230