qdio_thinint.c

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/*
 * Copyright IBM Corp. 2000, 2009
 * Author(s): Utz Bacher <[email protected]>
 *        Cornelia Huck <[email protected]>
 *        Jan Glauber <[email protected]>
 */
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/kernel_stat.h>
#include <linux/atomic.h>
#include <asm/debug.h>
#include <asm/qdio.h>
#include <asm/airq.h>
#include <asm/isc.h>

#include "cio.h"
#include "ioasm.h"
#include "qdio.h"
#include "qdio_debug.h"

/*
 * Restriction: only 63 iqdio subchannels would have its own indicator,
 * after that, subsequent subchannels share one indicator
 */
#define TIQDIO_NR_NONSHARED_IND     63
#define TIQDIO_NR_INDICATORS        (TIQDIO_NR_NONSHARED_IND + 1)
#define TIQDIO_SHARED_IND       63

/* device state change indicators */
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);

/* adapter local summary indicator */
static u8 *tiqdio_alsi;

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_read(&q_indicators[i].count)) {
            atomic_set(&q_indicators[i].count, 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)
{
    int i;

    if (!addr)
        return;
    i = ((unsigned long)addr - (unsigned long)q_indicators) /
        sizeof(struct indicator_t);
    atomic_dec(&q_indicators[i].count);
}

void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
{
    mutex_lock(&tiq_list_lock);
    BUG_ON(irq_ptr->nr_input_qs < 1);
    list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
    mutex_unlock(&tiq_list_lock);
    xchg(irq_ptr->dsci, 1 << 7);
}

void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
{
    struct qdio_q *q;

    BUG_ON(irq_ptr->nr_input_qs < 1);
    q = irq_ptr->input_qs[0];
    /* if establish triggered an error */
    if (!q || !q->entry.prev || !q->entry.next)
        return;

    mutex_lock(&tiq_list_lock);
    list_del_rcu(&q->entry);
    mutex_unlock(&tiq_list_lock);
    synchronize_rcu();
}

static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
{
    return irq_ptr->nr_input_qs > 1;
}

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

static inline int shared_ind(struct qdio_irq *irq_ptr)
{
    return references_shared_dsci(irq_ptr) ||
        has_multiple_inq_on_dsci(irq_ptr);
}

void clear_nonshared_ind(struct qdio_irq *irq_ptr)
{
    if (!is_thinint_irq(irq_ptr))
        return;
    if (shared_ind(irq_ptr))
        return;
    xchg(irq_ptr->dsci, 0);
}

int test_nonshared_ind(struct qdio_irq *irq_ptr)
{
    if (!is_thinint_irq(irq_ptr))
        return 0;
    if (shared_ind(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);
}

static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
{
    struct qdio_q *q;
    int i;

    for_each_input_queue(irq, q, i) {
        if (!references_shared_dsci(irq) &&
            has_multiple_inq_on_dsci(irq))
            xchg(q->irq_ptr->dsci, 0);

        if (q->u.in.queue_start_poll) {
            /* skip if polling is enabled or already in work */
            if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
                         &q->u.in.queue_irq_state)) {
                qperf_inc(q, int_discarded);
                continue;
            }

            /* avoid dsci clear here, done after processing */
            q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
                         q->irq_ptr->int_parm);
        } else {
            if (!shared_ind(q->irq_ptr))
                xchg(q->irq_ptr->dsci, 0);

            /*
             * Call inbound processing but not directly
             * since that could starve other thinint queues.
             */
            tasklet_schedule(&q->tasklet);
        }
    }
}

static void tiqdio_thinint_handler(void *alsi, void *data)
{
    u32 si_used = clear_shared_ind();
    struct qdio_q *q;

    last_ai_time = S390_lowcore.int_clock;
    kstat_cpu(smp_processor_id()).irqs[IOINT_QAI]++;

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

    /* check for work on all inbound thinint queues */
    list_for_each_entry_rcu(q, &tiq_list, entry) {
        struct qdio_irq *irq;

        /* only process queues from changed sets */
        irq = q->irq_ptr;
        if (unlikely(references_shared_dsci(irq))) {
            if (!si_used)
                continue;
        } else if (!*irq->dsci)
            continue;

        tiqdio_call_inq_handlers(irq);

        qperf_inc(q, adapter_int);
    }
    rcu_read_unlock();
}

static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
{
    struct scssc_area *scssc_area;
    int rc;

    scssc_area = (struct scssc_area *)irq_ptr->chsc_page;
    memset(scssc_area, 0, PAGE_SIZE);

    if (reset) {
        scssc_area->summary_indicator_addr = 0;
        scssc_area->subchannel_indicator_addr = 0;
    } else {
        scssc_area->summary_indicator_addr = virt_to_phys(tiqdio_alsi);
        scssc_area->subchannel_indicator_addr =
            virt_to_phys(irq_ptr->dsci);
    }

    scssc_area->request = (struct chsc_header) {
        .length = 0x0fe0,
        .code   = 0x0021,
    };
    scssc_area->operation_code = 0;
    scssc_area->ks = PAGE_DEFAULT_KEY >> 4;
    scssc_area->kc = PAGE_DEFAULT_KEY >> 4;
    scssc_area->isc = QDIO_AIRQ_ISC;
    scssc_area->schid = irq_ptr->schid;

    /* enable the time delay disablement facility */
    if (css_general_characteristics.aif_tdd)
        scssc_area->word_with_d_bit = 0x10000000;

    rc = chsc(scssc_area);
    if (rc)
        return -EIO;

    rc = chsc_error_from_response(scssc_area->response.code);
    if (rc) {
        DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
              scssc_area->response.code);
        DBF_ERROR_HEX(&scssc_area->response, sizeof(void *));
        return rc;
    }

    DBF_EVENT("setscind");
    DBF_HEX(&scssc_area->summary_indicator_addr, sizeof(unsigned long));
    DBF_HEX(&scssc_area->subchannel_indicator_addr, sizeof(unsigned long));
    return 0;
}

/* allocate non-shared indicators and shared indicator */
int __init tiqdio_allocate_memory(void)
{
    q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
                 GFP_KERNEL);
    if (!q_indicators)
        return -ENOMEM;
    return 0;
}

void tiqdio_free_memory(void)
{
    kfree(q_indicators);
}

int __init tiqdio_register_thinints(void)
{
    isc_register(QDIO_AIRQ_ISC);
    tiqdio_alsi = s390_register_adapter_interrupt(&tiqdio_thinint_handler,
                              NULL, QDIO_AIRQ_ISC);
    if (IS_ERR(tiqdio_alsi)) {
        DBF_EVENT("RTI:%lx", PTR_ERR(tiqdio_alsi));
        tiqdio_alsi = NULL;
        isc_unregister(QDIO_AIRQ_ISC);
        return -ENOMEM;
    }
    return 0;
}

int qdio_establish_thinint(struct qdio_irq *irq_ptr)
{
    if (!is_thinint_irq(irq_ptr))
        return 0;
    return set_subchannel_ind(irq_ptr, 0);
}

void qdio_setup_thinint(struct qdio_irq *irq_ptr)
{
    if (!is_thinint_irq(irq_ptr))
        return;
    irq_ptr->dsci = get_indicator();
    DBF_HEX(&irq_ptr->dsci, sizeof(void *));
}

void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
{
    if (!is_thinint_irq(irq_ptr))
        return;

    /* reset adapter interrupt indicators */
    set_subchannel_ind(irq_ptr, 1);
    put_indicator(irq_ptr->dsci);
}

void __exit tiqdio_unregister_thinints(void)
{
    WARN_ON(!list_empty(&tiq_list));

    if (tiqdio_alsi) {
        s390_unregister_adapter_interrupt(tiqdio_alsi, QDIO_AIRQ_ISC);
        isc_unregister(QDIO_AIRQ_ISC);
    }
}