icp-hv.c

Go to the documentation of this file.

/*
 * Copyright 2011 IBM Corporation.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */
#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 <asm/smp.h>
#include <asm/irq.h>
#include <asm/errno.h>
#include <asm/xics.h>
#include <asm/io.h>
#include <asm/hvcall.h>

static inline unsigned int icp_hv_get_xirr(unsigned char cppr)
{
    unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
    long rc;
    unsigned int ret = XICS_IRQ_SPURIOUS;

    rc = plpar_hcall(H_XIRR, retbuf, cppr);
    if (rc == H_SUCCESS) {
        ret = (unsigned int)retbuf[0];
    } else {
        pr_err("%s: bad return code xirr cppr=0x%x returned %ld\n",
            __func__, cppr, rc);
        WARN_ON_ONCE(1);
    }

    return ret;
}

static inline void icp_hv_set_cppr(u8 value)
{
    long rc = plpar_hcall_norets(H_CPPR, value);
    if (rc != H_SUCCESS) {
        pr_err("%s: bad return code cppr cppr=0x%x returned %ld\n",
            __func__, value, rc);
        WARN_ON_ONCE(1);
    }
}

static inline void icp_hv_set_xirr(unsigned int value)
{
    long rc = plpar_hcall_norets(H_EOI, value);
    if (rc != H_SUCCESS) {
        pr_err("%s: bad return code eoi xirr=0x%x returned %ld\n",
            __func__, value, rc);
        WARN_ON_ONCE(1);
        icp_hv_set_cppr(value >> 24);
    }
}

static inline void icp_hv_set_qirr(int n_cpu , u8 value)
{
    int hw_cpu = get_hard_smp_processor_id(n_cpu);
    long rc;

    /* Make sure all previous accesses are ordered before IPI sending */
    mb();
    rc = plpar_hcall_norets(H_IPI, hw_cpu, value);
    if (rc != H_SUCCESS) {
        pr_err("%s: bad return code qirr cpu=%d hw_cpu=%d mfrr=0x%x "
            "returned %ld\n", __func__, n_cpu, hw_cpu, value, rc);
        WARN_ON_ONCE(1);
    }
}

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

    iosync();
    icp_hv_set_xirr((xics_pop_cppr() << 24) | hw_irq);
}

static void icp_hv_teardown_cpu(void)
{
    int cpu = smp_processor_id();

    /* Clear any pending IPI */
    icp_hv_set_qirr(cpu, 0xff);
}

static void icp_hv_flush_ipi(void)
{
    /* We take the ipi irq but and never return so we
     * need to EOI the IPI, but want to leave our priority 0
     *
     * should we check all the other interrupts too?
     * should we be flagging idle loop instead?
     * or creating some task to be scheduled?
     */

    icp_hv_set_xirr((0x00 << 24) | XICS_IPI);
}

static unsigned int icp_hv_get_irq(void)
{
    unsigned int xirr = icp_hv_get_xirr(xics_cppr_top());
    unsigned int vec = xirr & 0x00ffffff;
    unsigned int irq;

    if (vec == XICS_IRQ_SPURIOUS)
        return NO_IRQ;

    irq = irq_find_mapping(xics_host, vec);
    if (likely(irq != NO_IRQ)) {
        xics_push_cppr(vec);
        return irq;
    }

    /* We don't have a linux mapping, so have rtas mask it. */
    xics_mask_unknown_vec(vec);

    /* We might learn about it later, so EOI it */
    icp_hv_set_xirr(xirr);

    return NO_IRQ;
}

static void icp_hv_set_cpu_priority(unsigned char cppr)
{
    xics_set_base_cppr(cppr);
    icp_hv_set_cppr(cppr);
    iosync();
}

#ifdef CONFIG_SMP

static void icp_hv_cause_ipi(int cpu, unsigned long data)
{
    icp_hv_set_qirr(cpu, IPI_PRIORITY);
}

static irqreturn_t icp_hv_ipi_action(int irq, void *dev_id)
{
    int cpu = smp_processor_id();

    icp_hv_set_qirr(cpu, 0xff);

    return smp_ipi_demux();
}

#endif /* CONFIG_SMP */

static const struct icp_ops icp_hv_ops = {
    .get_irq    = icp_hv_get_irq,
    .eoi        = icp_hv_eoi,
    .set_priority   = icp_hv_set_cpu_priority,
    .teardown_cpu   = icp_hv_teardown_cpu,
    .flush_ipi  = icp_hv_flush_ipi,
#ifdef CONFIG_SMP
    .ipi_action = icp_hv_ipi_action,
    .cause_ipi  = icp_hv_cause_ipi,
#endif
};

int icp_hv_init(void)
{
    struct device_node *np;

    np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xicp");
    if (!np)
        np = of_find_node_by_type(NULL,
                    "PowerPC-External-Interrupt-Presentation");
    if (!np)
        return -ENODEV;

    icp_ops = &icp_hv_ops;

    return 0;
}