drivers/s390/cio/qdio_thinint.c

Source file repositories/reference/linux-study-clean/drivers/s390/cio/qdio_thinint.c

File Facts

System
Linux kernel
Corpus path
drivers/s390/cio/qdio_thinint.c
Extension
.c
Size
5198 bytes
Lines
226
Domain
Driver Families
Bucket
drivers/s390
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct indicator_t {
	u32 ind;	/* u32 because of compare-and-swap performance */
	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
};

/* list of thin interrupt input queues */
static LIST_HEAD(tiq_list);
static DEFINE_MUTEX(tiq_list_lock);

static struct indicator_t *q_indicators;

u64 last_ai_time;

/* returns addr for the device state change indicator */
static u32 *get_indicator(void)
{
	int i;

	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
			return &q_indicators[i].ind;

	/* use the shared indicator */
	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
	return &q_indicators[TIQDIO_SHARED_IND].ind;
}

static void put_indicator(u32 *addr)
{
	struct indicator_t *ind = container_of(addr, struct indicator_t, ind);

	if (!addr)
		return;
	atomic_dec(&ind->count);
}

static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
{
	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
}

int test_nonshared_ind(struct qdio_irq *irq_ptr)
{
	if (!is_thinint_irq(irq_ptr))
		return 0;
	if (references_shared_dsci(irq_ptr))
		return 0;
	if (*irq_ptr->dsci)
		return 1;
	else
		return 0;
}

static inline u32 clear_shared_ind(void)
{
	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
		return 0;
	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
}

/**
 * tiqdio_thinint_handler - thin interrupt handler for qdio
 * @airq: pointer to adapter interrupt descriptor
 * @tpi_info: interrupt information (e.g. floating vs directed -- unused)
 */
static void tiqdio_thinint_handler(struct airq_struct *airq,
				   struct tpi_info *tpi_info)
{
	u64 irq_time = get_lowcore()->int_clock.tod;
	u32 si_used = clear_shared_ind();
	struct qdio_irq *irq;

	last_ai_time = irq_time;
	inc_irq_stat(IRQIO_QAI);

	/* protect tiq_list entries, only changed in activate or shutdown */
	rcu_read_lock();

	list_for_each_entry_rcu(irq, &tiq_list, entry) {
		/* only process queues from changed sets */
		if (unlikely(references_shared_dsci(irq))) {
			if (!si_used)
				continue;
		} else {
			if (!*irq->dsci)
				continue;

			xchg(irq->dsci, 0);
		}

Annotation

Implementation Notes