/*
 * 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/threads.h>
#include <linux/kernel.h>
#include <linux/irq.h>
#include <linux/debugfs.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/delay.h>

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

/* Globals common to all ICP/ICS implementations */
const struct icp_ops    *icp_ops;

unsigned int xics_default_server                = 0xff;
unsigned int xics_default_distrib_server        = 0;
unsigned int xics_interrupt_server_size         = 8;

DEFINE_PER_CPU(struct xics_cppr, xics_cppr);

struct irq_domain *xics_host;

static LIST_HEAD(ics_list);

void xics_update_irq_servers(void)
{
        int i, j;
        struct device_node *np;
        u32 ilen;
        const __be32 *ireg;
        u32 hcpuid;

        /* Find the server numbers for the boot cpu. */
        np = of_get_cpu_node(boot_cpuid, NULL);
        BUG_ON(!np);

        hcpuid = get_hard_smp_processor_id(boot_cpuid);
        xics_default_server = xics_default_distrib_server = hcpuid;

        pr_devel("xics: xics_default_server = 0x%x\n", xics_default_server);

        ireg = of_get_property(np, "ibm,ppc-interrupt-gserver#s", &ilen);
        if (!ireg) {
                of_node_put(np);
                return;
        }

        i = ilen / sizeof(int);

        /* Global interrupt distribution server is specified in the last
         * entry of "ibm,ppc-interrupt-gserver#s" property. Get the last
         * entry fom this property for current boot cpu id and use it as
         * default distribution server
         */
        for (j = 0; j < i; j += 2) {
                if (be32_to_cpu(ireg[j]) == hcpuid) {
                        xics_default_distrib_server = be32_to_cpu(ireg[j+1]);
                        break;
                }
        }
        pr_devel("xics: xics_default_distrib_server = 0x%x\n",
                 xics_default_distrib_server);
        of_node_put(np);
}

/* GIQ stuff, currently only supported on RTAS setups, will have
 * to be sorted properly for bare metal
 */
void xics_set_cpu_giq(unsigned int gserver, unsigned int join)
{
#ifdef CONFIG_PPC_RTAS
        int index;
        int status;

        if (!rtas_indicator_present(GLOBAL_INTERRUPT_QUEUE, NULL))
                return;

        index = (1UL << xics_interrupt_server_size) - 1 - gserver;

        status = rtas_set_indicator_fast(GLOBAL_INTERRUPT_QUEUE, index, join);

        WARN(status < 0, "set-indicator(%d, %d, %u) returned %d\n",
             GLOBAL_INTERRUPT_QUEUE, index, join, status);
#endif
}

void xics_setup_cpu(void)
{
        icp_ops->set_priority(LOWEST_PRIORITY);

        xics_set_cpu_giq(xics_default_distrib_server, 1);
}

void xics_mask_unknown_vec(unsigned int vec)
{
        struct ics *ics;

        pr_err("Interrupt 0x%x (real) is invalid, disabling it.\n", vec);

        list_for_each_entry(ics, &ics_list, link)
                ics->mask_unknown(ics, vec);
}


#ifdef CONFIG_SMP

static void xics_request_ipi(void)
{
        unsigned int ipi;

        ipi = irq_create_mapping(xics_host, XICS_IPI);
        BUG_ON(!ipi);

        /*
         * IPIs are marked IRQF_PERCPU. The handler was set in map.
         */
        BUG_ON(request_irq(ipi, icp_ops->ipi_action,
                           IRQF_PERCPU | IRQF_NO_THREAD, "IPI", NULL));
}

void __init xics_smp_probe(void)
{
        /* Register all the IPIs */
        xics_request_ipi();

        /* Setup cause_ipi callback based on which ICP is used */
        smp_ops->cause_ipi = icp_ops->cause_ipi;
}

#endif /* CONFIG_SMP */

void xics_teardown_cpu(void)
{
        struct xics_cppr *os_cppr = this_cpu_ptr(&xics_cppr);

        /*
         * we have to reset the cppr index to 0 because we're
         * not going to return from the IPI
         */
        os_cppr->index = 0;
        icp_ops->set_priority(0);
        icp_ops->teardown_cpu();
}

void xics_kexec_teardown_cpu(int secondary)
{
        xics_teardown_cpu();

        icp_ops->flush_ipi();

        /*
         * Some machines need to have at least one cpu in the GIQ,
         * so leave the master cpu in the group.
         */
        if (secondary)
                xics_set_cpu_giq(xics_default_distrib_server, 0);
}


#ifdef CONFIG_HOTPLUG_CPU

/* Interrupts are disabled. */
void xics_migrate_irqs_away(void)
{
        int cpu = smp_processor_id(), hw_cpu = hard_smp_processor_id();
        unsigned int irq, virq;
        struct irq_desc *desc;

        /* If we used to be the default server, move to the new "boot_cpuid" */
        if (hw_cpu == xics_default_server)
                xics_update_irq_servers();

        /* Reject any interrupt that was queued to us... */
        icp_ops->set_priority(0);

        /* Remove ourselves from the global interrupt queue */
        xics_set_cpu_giq(xics_default_distrib_server, 0);

        for_each_irq_desc(virq, desc) {
                struct irq_chip *chip;
                long server;
                unsigned long flags;
                struct ics *ics;

                /* We can't set affinity on ISA interrupts */
                if (virq < NUM_ISA_INTERRUPTS)
                        continue;
                /* We only need to migrate enabled IRQS */
                if (!desc->action)
                        continue;
                if (desc->irq_data.domain != xics_host)
                        continue;
                irq = desc->irq_data.hwirq;
                /* We need to get IPIs still. */
                if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
                        continue;
                chip = irq_desc_get_chip(desc);
                if (!chip || !chip->irq_set_affinity)
                        continue;

                raw_spin_lock_irqsave(&desc->lock, flags);

                /* Locate interrupt server */
                server = -1;
                ics = irq_desc_get_chip_data(desc);
                if (ics)
                        server = ics->get_server(ics, irq);
                if (server < 0) {
                        printk(KERN_ERR "%s: Can't find server for irq %d\n",
                               __func__, irq);
                        goto unlock;
                }

                /* We only support delivery to all cpus or to one cpu.
                 * The irq has to be migrated only in the single cpu
                 * case.
                 */
                if (server != hw_cpu)
                        goto unlock;

                /* This is expected during cpu offline. */
                if (cpu_online(cpu))
                        pr_warning("IRQ %u affinity broken off cpu %u\n",
                               virq, cpu);

                /* Reset affinity to all cpus */
                raw_spin_unlock_irqrestore(&desc->lock, flags);
                irq_set_affinity(virq, cpu_all_mask);
                continue;
unlock:
                raw_spin_unlock_irqrestore(&desc->lock, flags);
        }

        /* Allow "sufficient" time to drop any inflight IRQ's */
        mdelay(5);

        /*
         * Allow IPIs again. This is done at the very end, after migrating all
         * interrupts, the expectation is that we'll only get woken up by an IPI
         * interrupt beyond this point, but leave externals masked just to be
         * safe. If we're using icp-opal this may actually allow all
         * interrupts anyway, but that should be OK.
         */
        icp_ops->set_priority(DEFAULT_PRIORITY);

}
#endif /* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_SMP
/*
 * For the moment we only implement delivery to all cpus or one cpu.
 *
 * If the requested affinity is cpu_all_mask, we set global affinity.
 * If not we set it to the first cpu in the mask, even if multiple cpus
 * are set. This is so things like irqbalance (which set core and package
 * wide affinities) do the right thing.
 *
 * We need to fix this to implement support for the links
 */
int xics_get_irq_server(unsigned int virq, const struct cpumask *cpumask,
                        unsigned int strict_check)
{

        if (!distribute_irqs)
                return xics_default_server;

        if (!cpumask_subset(cpu_possible_mask, cpumask)) {
                int server = cpumask_first_and(cpu_online_mask, cpumask);

                if (server < nr_cpu_ids)
                        return get_hard_smp_processor_id(server);

                if (strict_check)
                        return -1;
        }

        /*
         * Workaround issue with some versions of JS20 firmware that
         * deliver interrupts to cpus which haven't been started. This
         * happens when using the maxcpus= boot option.
         */
        if (cpumask_equal(cpu_online_mask, cpu_present_mask))
                return xics_default_distrib_server;

        return xics_default_server;
}
#endif /* CONFIG_SMP */

static int xics_host_match(struct irq_domain *h, struct device_node *node,
                           enum irq_domain_bus_token bus_token)
{
        struct ics *ics;

        list_for_each_entry(ics, &ics_list, link)
                if (ics->host_match(ics, node))
                        return 1;

        return 0;
}

/* Dummies */
static void xics_ipi_unmask(struct irq_data *d) { }
static void xics_ipi_mask(struct irq_data *d) { }

static struct irq_chip xics_ipi_chip = {
        .name = "XICS",
        .irq_eoi = NULL, /* Patched at init time */
        .irq_mask = xics_ipi_mask,
        .irq_unmask = xics_ipi_unmask,
};

static int xics_host_map(struct irq_domain *h, unsigned int virq,
                         irq_hw_number_t hw)
{
        struct ics *ics;

        pr_devel("xics: map virq %d, hwirq 0x%lx\n", virq, hw);

        /*
         * Mark interrupts as edge sensitive by default so that resend
         * actually works. The device-tree parsing will turn the LSIs
         * back to level.
         */
        irq_clear_status_flags(virq, IRQ_LEVEL);

        /* Don't call into ICS for IPIs */
        if (hw == XICS_IPI) {
                irq_set_chip_and_handler(virq, &xics_ipi_chip,
                                         handle_percpu_irq);
                return 0;
        }

        /* Let the ICS setup the chip data */
        list_for_each_entry(ics, &ics_list, link)
                if (ics->map(ics, virq) == 0)
                        return 0;

        return -EINVAL;
}

static int xics_host_xlate(struct irq_domain *h, struct device_node *ct,
                           const u32 *intspec, unsigned int intsize,
                           irq_hw_number_t *out_hwirq, unsigned int *out_flags)

{
        *out_hwirq = intspec[0];

        /*
         * If intsize is at least 2, we look for the type in the second cell,
         * we assume the LSB indicates a level interrupt.
         */
        if (intsize > 1) {
                if (intspec[1] & 1)
                        *out_flags = IRQ_TYPE_LEVEL_LOW;
                else
                        *out_flags = IRQ_TYPE_EDGE_RISING;
        } else
                *out_flags = IRQ_TYPE_LEVEL_LOW;

        return 0;
}

int xics_set_irq_type(struct irq_data *d, unsigned int flow_type)
{
        /*
         * We only support these. This has really no effect other than setting
         * the corresponding descriptor bits mind you but those will in turn
         * affect the resend function when re-enabling an edge interrupt.
         *
         * Set set the default to edge as explained in map().
         */
        if (flow_type == IRQ_TYPE_DEFAULT || flow_type == IRQ_TYPE_NONE)
                flow_type = IRQ_TYPE_EDGE_RISING;

        if (flow_type != IRQ_TYPE_EDGE_RISING &&
            flow_type != IRQ_TYPE_LEVEL_LOW)
                return -EINVAL;

        irqd_set_trigger_type(d, flow_type);

        return IRQ_SET_MASK_OK_NOCOPY;
}

int xics_retrigger(struct irq_data *data)
{
        /*
         * We need to push a dummy CPPR when retriggering, since the subsequent
         * EOI will try to pop it. Passing 0 works, as the function hard codes
         * the priority value anyway.
         */
        xics_push_cppr(0);

        /* Tell the core to do a soft retrigger */
        return 0;
}

static const struct irq_domain_ops xics_host_ops = {
        .match = xics_host_match,
        .map = xics_host_map,
        .xlate = xics_host_xlate,
};

static void __init xics_init_host(void)
{
        xics_host = irq_domain_add_tree(NULL, &xics_host_ops, NULL);
        BUG_ON(xics_host == NULL);
        irq_set_default_host(xics_host);
}

void __init xics_register_ics(struct ics *ics)
{
        list_add(&ics->link, &ics_list);
}

static void __init xics_get_server_size(void)
{
        struct device_node *np;
        const __be32 *isize;

        /* We fetch the interrupt server size from the first ICS node
         * we find if any
         */
        np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xics");
        if (!np)
                return;
        isize = of_get_property(np, "ibm,interrupt-server#-size", NULL);
        if (!isize)
                return;
        xics_interrupt_server_size = be32_to_cpu(*isize);
        of_node_put(np);
}

void __init xics_init(void)
{
        int rc = -1;

        /* Fist locate ICP */
        if (firmware_has_feature(FW_FEATURE_LPAR))
                rc = icp_hv_init();
        if (rc < 0) {
                rc = icp_native_init();
                if (rc == -ENODEV)
                    rc = icp_opal_init();
        }
        if (rc < 0) {
                pr_warning("XICS: Cannot find a Presentation Controller !\n");
                return;
        }

        /* Copy get_irq callback over to ppc_md */
        ppc_md.get_irq = icp_ops->get_irq;

        /* Patch up IPI chip EOI */
        xics_ipi_chip.irq_eoi = icp_ops->eoi;

        /* Now locate ICS */
        rc = ics_rtas_init();
        if (rc < 0)
                rc = ics_opal_init();
        if (rc < 0)
                pr_warning("XICS: Cannot find a Source Controller !\n");

        /* Initialize common bits */
        xics_get_server_size();
        xics_update_irq_servers();
        xics_init_host();
        xics_setup_cpu();
}