ics-rtas.c

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#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/irq.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#include <linux/msi.h>

#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/irq.h>
#include <asm/errno.h>
#include <asm/xics.h>
#include <asm/rtas.h>

/* RTAS service tokens */
static int ibm_get_xive;
static int ibm_set_xive;
static int ibm_int_on;
static int ibm_int_off;

static int ics_rtas_map(struct ics *ics, unsigned int virq);
static void ics_rtas_mask_unknown(struct ics *ics, unsigned long vec);
static long ics_rtas_get_server(struct ics *ics, unsigned long vec);
static int ics_rtas_host_match(struct ics *ics, struct device_node *node);

/* Only one global & state struct ics */
static struct ics ics_rtas = {
    .map        = ics_rtas_map,
    .mask_unknown   = ics_rtas_mask_unknown,
    .get_server = ics_rtas_get_server,
    .host_match = ics_rtas_host_match,
};

static void ics_rtas_unmask_irq(struct irq_data *d)
{
    unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
    int call_status;
    int server;

    pr_devel("xics: unmask virq %d [hw 0x%x]\n", d->irq, hw_irq);

    if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
        return;

    server = xics_get_irq_server(d->irq, d->affinity, 0);

    call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, server,
                DEFAULT_PRIORITY);
    if (call_status != 0) {
        printk(KERN_ERR
            "%s: ibm_set_xive irq %u server %x returned %d\n",
            __func__, hw_irq, server, call_status);
        return;
    }

    /* Now unmask the interrupt (often a no-op) */
    call_status = rtas_call(ibm_int_on, 1, 1, NULL, hw_irq);
    if (call_status != 0) {
        printk(KERN_ERR "%s: ibm_int_on irq=%u returned %d\n",
            __func__, hw_irq, call_status);
        return;
    }
}

static unsigned int ics_rtas_startup(struct irq_data *d)
{
#ifdef CONFIG_PCI_MSI
    /*
     * The generic MSI code returns with the interrupt disabled on the
     * card, using the MSI mask bits. Firmware doesn't appear to unmask
     * at that level, so we do it here by hand.
     */
    if (d->msi_desc)
        unmask_msi_irq(d);
#endif
    /* unmask it */
    ics_rtas_unmask_irq(d);
    return 0;
}

static void ics_rtas_mask_real_irq(unsigned int hw_irq)
{
    int call_status;

    if (hw_irq == XICS_IPI)
        return;

    call_status = rtas_call(ibm_int_off, 1, 1, NULL, hw_irq);
    if (call_status != 0) {
        printk(KERN_ERR "%s: ibm_int_off irq=%u returned %d\n",
            __func__, hw_irq, call_status);
        return;
    }

    /* Have to set XIVE to 0xff to be able to remove a slot */
    call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq,
                xics_default_server, 0xff);
    if (call_status != 0) {
        printk(KERN_ERR "%s: ibm_set_xive(0xff) irq=%u returned %d\n",
            __func__, hw_irq, call_status);
        return;
    }
}

static void ics_rtas_mask_irq(struct irq_data *d)
{
    unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);

    pr_devel("xics: mask virq %d [hw 0x%x]\n", d->irq, hw_irq);

    if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
        return;
    ics_rtas_mask_real_irq(hw_irq);
}

static int ics_rtas_set_affinity(struct irq_data *d,
                 const struct cpumask *cpumask,
                 bool force)
{
    unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
    int status;
    int xics_status[2];
    int irq_server;

    if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
        return -1;

    status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq);

    if (status) {
        printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n",
            __func__, hw_irq, status);
        return -1;
    }

    irq_server = xics_get_irq_server(d->irq, cpumask, 1);
    if (irq_server == -1) {
        char cpulist[128];
        cpumask_scnprintf(cpulist, sizeof(cpulist), cpumask);
        printk(KERN_WARNING
            "%s: No online cpus in the mask %s for irq %d\n",
            __func__, cpulist, d->irq);
        return -1;
    }

    status = rtas_call(ibm_set_xive, 3, 1, NULL,
               hw_irq, irq_server, xics_status[1]);

    if (status) {
        printk(KERN_ERR "%s: ibm,set-xive irq=%u returns %d\n",
            __func__, hw_irq, status);
        return -1;
    }

    return IRQ_SET_MASK_OK;
}

static struct irq_chip ics_rtas_irq_chip = {
    .name = "XICS",
    .irq_startup = ics_rtas_startup,
    .irq_mask = ics_rtas_mask_irq,
    .irq_unmask = ics_rtas_unmask_irq,
    .irq_eoi = NULL, /* Patched at init time */
    .irq_set_affinity = ics_rtas_set_affinity
};

static int ics_rtas_map(struct ics *ics, unsigned int virq)
{
    unsigned int hw_irq = (unsigned int)virq_to_hw(virq);
    int status[2];
    int rc;

    if (WARN_ON(hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS))
        return -EINVAL;

    /* Check if RTAS knows about this interrupt */
    rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq);
    if (rc)
        return -ENXIO;

    irq_set_chip_and_handler(virq, &ics_rtas_irq_chip, handle_fasteoi_irq);
    irq_set_chip_data(virq, &ics_rtas);

    return 0;
}

static void ics_rtas_mask_unknown(struct ics *ics, unsigned long vec)
{
    ics_rtas_mask_real_irq(vec);
}

static long ics_rtas_get_server(struct ics *ics, unsigned long vec)
{
    int rc, status[2];

    rc = rtas_call(ibm_get_xive, 1, 3, status, vec);
    if (rc)
        return -1;
    return status[0];
}

static int ics_rtas_host_match(struct ics *ics, struct device_node *node)
{
    /* IBM machines have interrupt parents of various funky types for things
     * like vdevices, events, etc... The trick we use here is to match
     * everything here except the legacy 8259 which is compatible "chrp,iic"
     */
    return !of_device_is_compatible(node, "chrp,iic");
}

int ics_rtas_init(void)
{
    ibm_get_xive = rtas_token("ibm,get-xive");
    ibm_set_xive = rtas_token("ibm,set-xive");
    ibm_int_on  = rtas_token("ibm,int-on");
    ibm_int_off = rtas_token("ibm,int-off");

    /* We enable the RTAS "ICS" if RTAS is present with the
     * appropriate tokens
     */
    if (ibm_get_xive == RTAS_UNKNOWN_SERVICE ||
        ibm_set_xive == RTAS_UNKNOWN_SERVICE)
        return -ENODEV;

    /* We need to patch our irq chip's EOI to point to the
     * right ICP
     */
    ics_rtas_irq_chip.irq_eoi = icp_ops->eoi;

    /* Register ourselves */
    xics_register_ics(&ics_rtas);

    return 0;
}