source: rtems/c/src/lib/libbsp/sparc/shared/irq/genirq.c @ 5c93fb3b

/*
 * Generic interrupt helpers mainly for GRLIB PCI peripherals
 * 
 * COPYRIGHT (c) 2008.
 * Cobham Gaisler AB.
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rtems.org/license/LICENSE.
 */

#include <rtems.h>
#include <stdlib.h>
#include <string.h>
#include <bsp/genirq.h>

struct genirq_handler_entry {
        struct genirq_handler_entry     *next;          /* Next ISR entry for this IRQ number */
        genirq_handler                  isr;            /* ISR function called upon IRQ */
        void                            *arg;           /* custom argument to ISR */
        int                             enabled;        /* Inidicates if IRQ is enabled */
};

struct genirq_irq_entry {
        struct genirq_handler_entry     *head;
        struct genirq_stats             stats;
};

struct genirq_priv {
        /* Maximum number of interrupt */
        int                             genirq_max;
        /* IRQ Table index N reflect IRQ number N */
        struct genirq_irq_entry         genirq_table[1]; /* Length depends on */
};

genirq_t genirq_init(int number_of_irqs)
{
        int size;
        struct genirq_priv *priv;

        size = sizeof(int) +
               number_of_irqs * sizeof(struct genirq_irq_entry);

        priv = (struct genirq_priv *)malloc(size);
        if ( !priv )
                return NULL;
        memset(priv, 0, size);
        priv->genirq_max = number_of_irqs - 1;
        return priv;
}

void genirq_destroy(genirq_t d)
{
        struct genirq_priv *priv = d;
        struct genirq_irq_entry *irqentry;
        struct genirq_handler_entry *isrentry, *tmp;
        int i;

        /* Free all registered interrupts */
        for ( i=0; i<priv->genirq_max; i++) {
                irqentry = &priv->genirq_table[i];
                isrentry = irqentry->head;
                while ( isrentry ) {
                        tmp = isrentry;
                        isrentry = isrentry->next;
                        free(tmp);
                }
        }

        free(priv);
}

int genirq_check(genirq_t d, int irq)
{
        struct genirq_priv *priv = d;

        if ( (irq <= 0) || (irq > priv->genirq_max) )
                return -1;
        else
                return 0;
}

int genirq_register(genirq_t d, int irq, genirq_handler isr, void *arg)
{
        struct genirq_priv *priv = d;
        struct genirq_irq_entry *irqentry;
        struct genirq_handler_entry *isrentry, *newentry;
        rtems_interrupt_level level;
        
        if ( genirq_check(d, irq) )
                return -1;

        newentry = malloc(sizeof(*newentry));
        if ( !newentry )
                return -1;

        /* Initialize ISR entry */
        newentry->isr     = isr;
        newentry->arg     = arg;
        newentry->enabled = 0;

        rtems_interrupt_disable(level);

        /* Insert new ISR entry first into table */
        irqentry = &priv->genirq_table[irq];
        isrentry = irqentry->head;
        irqentry->head = newentry;
        newentry->next = isrentry;

        rtems_interrupt_enable(level);

        if ( isrentry )
                return 1; /* This is the first handler on this IRQ */
        return 0;
}

int genirq_unregister(genirq_t d, int irq, genirq_handler isr, void *arg)
{
        struct genirq_priv *priv = d;
        struct genirq_irq_entry *irqentry;
        struct genirq_handler_entry *isrentry, **prev;
        rtems_interrupt_level level;
        int ret;

        if ( genirq_check(d, irq) )
                return -1;

        /* Remove isr[arg] from ISR list */
        irqentry = &priv->genirq_table[irq];
        ret = -1;

        rtems_interrupt_disable(level);

        prev = &irqentry->head;
        isrentry = irqentry->head;
        while ( isrentry ) {
                if ( (isrentry->arg == arg) && (isrentry->isr == isr) ) {
                        /* Found ISR, remove it from list */
                        if ( isrentry->enabled ) {
                                /* Can not remove enabled ISRs, disable first */
                                ret = 1;
                                break;
                        }
                        *prev = isrentry->next;
                        ret = 0;
                        break;
                }
                prev = &isrentry->next;
                isrentry = isrentry->next;
        }

        rtems_interrupt_enable(level);

        return ret;
}

/* Enables or Disables ISR handler. Internal function to reduce footprint
 * of enable/disable functions.
 *
 * \param action 1=enable, 0=disable ISR
 */
static int genirq_set_active(
        struct genirq_priv *priv,
        int irq,
        genirq_handler isr,
        void *arg,
        int action)
{
        struct genirq_irq_entry *irqentry;
        struct genirq_handler_entry *isrentry, *e = NULL;
        int enabled;

        if ( genirq_check(priv, irq) )
                return -1;

        /* Find isr[arg] in ISR list */
        irqentry = &priv->genirq_table[irq];
        enabled = 0;

        isrentry = irqentry->head;
        while ( isrentry ) {
                if ( (isrentry->arg == arg) && (isrentry->isr == isr) ) {
                        /* Found ISR */
                        if ( isrentry->enabled == action ) {
                                /* The ISR is already enabled or disabled 
                                 * depending on request, neccessary actions
                                 * were taken last time the same action was
                                 * requested.
                                 */
                                return 1;
                        }
                        e = isrentry;
                } else {
                        enabled += isrentry->enabled;
                }
                isrentry = isrentry->next;
        }

        if ( !e )
                return -1;

        e->enabled = action;

        return enabled;
}

int genirq_enable(genirq_t d, int irq, genirq_handler isr, void *arg)
{
        struct genirq_priv *priv = d;
        return genirq_set_active(priv, irq, isr, arg, 1);
}

int genirq_disable(genirq_t d, int irq, genirq_handler isr, void *arg)
{
        struct genirq_priv *priv = d;
        return genirq_set_active(priv, irq, isr, arg, 0);
}

void genirq_doirq(genirq_t d, int irq)
{
        struct genirq_priv *priv = d;
        struct genirq_irq_entry *irqentry;
        struct genirq_handler_entry *isrentry;
        int enabled;

        irqentry = &priv->genirq_table[irq];
        irqentry->stats.irq_cnt++;
        
        enabled = 0;

        isrentry = irqentry->head;
        while ( isrentry ) {
                if ( isrentry->enabled ) {
                        enabled = 1;
                        /* Call the ISR */
                        isrentry->isr(isrentry->arg);
                }
                isrentry = isrentry->next;
        }

        /* Was the IRQ an IRQ without source? */
        if ( enabled == 0 ) {
                /* This should not happen */
                printk("Spurious IRQ happened on IRQ %d\n", irq);
        }
}