arch/powerpc/platforms/pseries/io_event_irq.c

Source file repositories/reference/linux-study-clean/arch/powerpc/platforms/pseries/io_event_irq.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/platforms/pseries/io_event_irq.c
Extension
.c
Size
5017 bytes
Lines
162
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

* int event_handler(struct notifier_block *nb, unsigned long val, void *data) {
 * 	p = (struct pseries_io_event_sect_data *) data;
 * 	if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE;
 * 		:
 * 		:
 * 	return NOTIFY_OK;
 * }
 * struct notifier_block event_nb = {
 * 	.notifier_call = event_handler,
 * }
 *
 * Registration:
 * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb);
 *
 * Unregistration:
 * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb);
 */

ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);

static int ioei_check_exception_token;

static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;

/**
 * Find the data portion of an IO Event section from event log.
 * @elog: RTAS error/event log.
 *
 * Return:
 * 	pointer to a valid IO event section data. NULL if not found.
 */
static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog)
{
	struct pseries_errorlog *sect;

	/* We should only ever get called for io-event interrupts, but if
	 * we do get called for another type then something went wrong so
	 * make some noise about it.
	 * RTAS_TYPE_IO only exists in extended event log version 6 or later.
	 * No need to check event log version.
	 */
	if (unlikely(rtas_error_type(elog) != RTAS_TYPE_IO)) {
		printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d",
			    rtas_error_type(elog));
		return NULL;
	}

	sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT);
	if (unlikely(!sect)) {
		printk_once(KERN_WARNING "io_event_irq: RTAS extended event "
			    "log does not contain an IO Event section. "
			    "Could be a bug in system firmware!\n");
		return NULL;
	}
	return (struct pseries_io_event *) &sect->data;
}

/*
 * PAPR:
 * - check-exception returns the first found error or event and clear that
 *   error or event so it is reported once.
 * - Each interrupt returns one event. If a plateform chooses to report
 *   multiple events through a single interrupt, it must ensure that the
 *   interrupt remains asserted until check-exception has been used to
 *   process all out-standing events for that interrupt.
 *
 * Implementation notes:
 * - Events must be processed in the order they are returned. Hence,
 *   sequential in nature.
 * - The owner of an event is determined by combinations of scope,
 *   event type, and sub-type. There is no easy way to pre-sort clients
 *   by scope or event type alone. For example, Torrent ISR route change
 *   event is reported with scope 0x00 (Not Applicable) rather than
 *   0x3B (Torrent-hub). It is better to let the clients to identify
 *   who owns the event.
 */

static irqreturn_t ioei_interrupt(int irq, void *dev_id)
{
	struct pseries_io_event *event;
	int rtas_rc;

	for (;;) {
		rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL,
				    RTAS_VECTOR_EXTERNAL_INTERRUPT,
				    virq_to_hw(irq),
				    RTAS_IO_EVENTS, 1 /* Time Critical */,
				    __pa(ioei_rtas_buf),
				    RTAS_DATA_BUF_SIZE);

Annotation

Implementation Notes