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 61 ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list); 62 EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list); 63 64 static int ioei_check_exception_token; 65 66 static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned; 67 68 /** 69 * Find the data portion of an IO Event section from event log. 70 * @elog: RTAS error/event log. 71 * 72 * Return: 73 * pointer to a valid IO event section data. NULL if not found. 74 */ 75 static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog) 76 { 77 struct pseries_errorlog *sect; 78 79 /* We should only ever get called for io-event interrupts, but if 80 * we do get called for another type then something went wrong so 81 * make some noise about it. 82 * RTAS_TYPE_IO only exists in extended event log version 6 or later. 83 * No need to check event log version. 84 */ 85 if (unlikely(rtas_error_type(elog) != RTAS_TYPE_IO)) { 86 printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d", 87 rtas_error_type(elog)); 88 return NULL; 89 } 90 91 sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT); 92 if (unlikely(!sect)) { 93 printk_once(KERN_WARNING "io_event_irq: RTAS extended event " 94 "log does not contain an IO Event section. " 95 "Could be a bug in system firmware!\n"); 96 return NULL; 97 } 98 return (struct pseries_io_event *) §->data; 99 } 100 101 /* 102 * PAPR: 103 * - check-exception returns the first found error or event and clear that 104 * error or event so it is reported once. 105 * - Each interrupt returns one event. If a plateform chooses to report 106 * multiple events through a single interrupt, it must ensure that the 107 * interrupt remains asserted until check-exception has been used to 108 * process all out-standing events for that interrupt. 109 * 110 * Implementation notes: 111 * - Events must be processed in the order they are returned. Hence, 112 * sequential in nature. 113 * - The owner of an event is determined by combinations of scope, 114 * event type, and sub-type. There is no easy way to pre-sort clients 115 * by scope or event type alone. For example, Torrent ISR route change 116 * event is reported with scope 0x00 (Not Applicatable) rather than 117 * 0x3B (Torrent-hub). It is better to let the clients to identify 118 * who owns the event. 119 */ 120 121 static irqreturn_t ioei_interrupt(int irq, void *dev_id) 122 { 123 struct pseries_io_event *event; 124 int rtas_rc; 125 126 for (;;) { 127 rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL, 128 RTAS_VECTOR_EXTERNAL_INTERRUPT, 129 virq_to_hw(irq), 130 RTAS_IO_EVENTS, 1 /* Time Critical */, 131 __pa(ioei_rtas_buf), 132 RTAS_DATA_BUF_SIZE); 133 if (rtas_rc != 0) 134 break; 135 136 event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf); 137 if (!event) 138 continue; 139 140 atomic_notifier_call_chain(&pseries_ioei_notifier_list, 141 0, event); 142 } 143 return IRQ_HANDLED; 144 } 145 146 static int __init ioei_init(void) 147 { 148 struct device_node *np; 149 150 ioei_check_exception_token = rtas_token("check-exception"); 151 if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE) 152 return -ENODEV; 153 154 np = of_find_node_by_path("/event-sources/ibm,io-events"); 155 if (np) { 156 request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT"); 157 pr_info("IBM I/O event interrupts enabled\n"); 158 of_node_put(np); 159 } else { 160 return -ENODEV; 161 } 162 return 0; 163 } 164 machine_subsys_initcall(pseries, ioei_init); 165 166