1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright 2010 2011 Mark Nelson and Tseng-Hui (Frank) Lin, IBM Corporation 4 */ 5 6 #include <linux/errno.h> 7 #include <linux/slab.h> 8 #include <linux/export.h> 9 #include <linux/irq.h> 10 #include <linux/interrupt.h> 11 #include <linux/of.h> 12 #include <linux/list.h> 13 #include <linux/notifier.h> 14 15 #include <asm/machdep.h> 16 #include <asm/rtas.h> 17 #include <asm/irq.h> 18 #include <asm/io_event_irq.h> 19 20 #include "pseries.h" 21 22 /* 23 * IO event interrupt is a mechanism provided by RTAS to return 24 * information about hardware error and non-error events. Device 25 * drivers can register their event handlers to receive events. 26 * Device drivers are expected to use atomic_notifier_chain_register() 27 * and atomic_notifier_chain_unregister() to register and unregister 28 * their event handlers. Since multiple IO event types and scopes 29 * share an IO event interrupt, the event handlers are called one 30 * by one until the IO event is claimed by one of the handlers. 31 * The event handlers are expected to return NOTIFY_OK if the 32 * event is handled by the event handler or NOTIFY_DONE if the 33 * event does not belong to the handler. 34 * 35 * Usage: 36 * 37 * Notifier function: 38 * #include <asm/io_event_irq.h> 39 * int event_handler(struct notifier_block *nb, unsigned long val, void *data) { 40 * p = (struct pseries_io_event_sect_data *) data; 41 * if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE; 42 * : 43 * : 44 * return NOTIFY_OK; 45 * } 46 * struct notifier_block event_nb = { 47 * .notifier_call = event_handler, 48 * } 49 * 50 * Registration: 51 * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb); 52 * 53 * Unregistration: 54 * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb); 55 */ 56 57 ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list); 58 EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list); 59 60 static int ioei_check_exception_token; 61 62 static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned; 63 64 /** 65 * Find the data portion of an IO Event section from event log. 66 * @elog: RTAS error/event log. 67 * 68 * Return: 69 * pointer to a valid IO event section data. NULL if not found. 70 */ 71 static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog) 72 { 73 struct pseries_errorlog *sect; 74 75 /* We should only ever get called for io-event interrupts, but if 76 * we do get called for another type then something went wrong so 77 * make some noise about it. 78 * RTAS_TYPE_IO only exists in extended event log version 6 or later. 79 * No need to check event log version. 80 */ 81 if (unlikely(rtas_error_type(elog) != RTAS_TYPE_IO)) { 82 printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d", 83 rtas_error_type(elog)); 84 return NULL; 85 } 86 87 sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT); 88 if (unlikely(!sect)) { 89 printk_once(KERN_WARNING "io_event_irq: RTAS extended event " 90 "log does not contain an IO Event section. " 91 "Could be a bug in system firmware!\n"); 92 return NULL; 93 } 94 return (struct pseries_io_event *) §->data; 95 } 96 97 /* 98 * PAPR: 99 * - check-exception returns the first found error or event and clear that 100 * error or event so it is reported once. 101 * - Each interrupt returns one event. If a plateform chooses to report 102 * multiple events through a single interrupt, it must ensure that the 103 * interrupt remains asserted until check-exception has been used to 104 * process all out-standing events for that interrupt. 105 * 106 * Implementation notes: 107 * - Events must be processed in the order they are returned. Hence, 108 * sequential in nature. 109 * - The owner of an event is determined by combinations of scope, 110 * event type, and sub-type. There is no easy way to pre-sort clients 111 * by scope or event type alone. For example, Torrent ISR route change 112 * event is reported with scope 0x00 (Not Applicable) rather than 113 * 0x3B (Torrent-hub). It is better to let the clients to identify 114 * who owns the event. 115 */ 116 117 static irqreturn_t ioei_interrupt(int irq, void *dev_id) 118 { 119 struct pseries_io_event *event; 120 int rtas_rc; 121 122 for (;;) { 123 rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL, 124 RTAS_VECTOR_EXTERNAL_INTERRUPT, 125 virq_to_hw(irq), 126 RTAS_IO_EVENTS, 1 /* Time Critical */, 127 __pa(ioei_rtas_buf), 128 RTAS_DATA_BUF_SIZE); 129 if (rtas_rc != 0) 130 break; 131 132 event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf); 133 if (!event) 134 continue; 135 136 atomic_notifier_call_chain(&pseries_ioei_notifier_list, 137 0, event); 138 } 139 return IRQ_HANDLED; 140 } 141 142 static int __init ioei_init(void) 143 { 144 struct device_node *np; 145 146 ioei_check_exception_token = rtas_token("check-exception"); 147 if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE) 148 return -ENODEV; 149 150 np = of_find_node_by_path("/event-sources/ibm,io-events"); 151 if (np) { 152 request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT"); 153 pr_info("IBM I/O event interrupts enabled\n"); 154 of_node_put(np); 155 } else { 156 return -ENODEV; 157 } 158 return 0; 159 } 160 machine_subsys_initcall(pseries, ioei_init); 161 162