// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2016-17 IBM Corp.
 */

#define pr_fmt(fmt) "vas: " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/of_platform.h>
#include <linux/of_address.h>
#include <linux/of.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <asm/prom.h>
#include <asm/xive.h>

#include "vas.h"

DEFINE_MUTEX(vas_mutex);
static LIST_HEAD(vas_instances);

static DEFINE_PER_CPU(int, cpu_vas_id);

static int vas_irq_fault_window_setup(struct vas_instance *vinst)
{
        int rc = 0;

        rc = request_threaded_irq(vinst->virq, vas_fault_handler,
                                vas_fault_thread_fn, 0, vinst->name, vinst);

        if (rc) {
                pr_err("VAS[%d]: Request IRQ(%d) failed with %d\n",
                                vinst->vas_id, vinst->virq, rc);
                goto out;
        }

        rc = vas_setup_fault_window(vinst);
        if (rc)
                free_irq(vinst->virq, vinst);

out:
        return rc;
}

static int init_vas_instance(struct platform_device *pdev)
{
        struct device_node *dn = pdev->dev.of_node;
        struct vas_instance *vinst;
        struct xive_irq_data *xd;
        uint32_t chipid, hwirq;
        struct resource *res;
        int rc, cpu, vasid;

        rc = of_property_read_u32(dn, "ibm,vas-id", &vasid);
        if (rc) {
                pr_err("No ibm,vas-id property for %s?\n", pdev->name);
                return -ENODEV;
        }

        rc = of_property_read_u32(dn, "ibm,chip-id", &chipid);
        if (rc) {
                pr_err("No ibm,chip-id property for %s?\n", pdev->name);
                return -ENODEV;
        }

        if (pdev->num_resources != 4) {
                pr_err("Unexpected DT configuration for [%s, %d]\n",
                                pdev->name, vasid);
                return -ENODEV;
        }

        vinst = kzalloc_obj(*vinst);
        if (!vinst)
                return -ENOMEM;

        vinst->name = kasprintf(GFP_KERNEL, "vas-%d", vasid);
        if (!vinst->name) {
                kfree(vinst);
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&vinst->node);
        ida_init(&vinst->ida);
        mutex_init(&vinst->mutex);
        vinst->vas_id = vasid;
        vinst->pdev = pdev;

        res = &pdev->resource[0];
        vinst->hvwc_bar_start = res->start;

        res = &pdev->resource[1];
        vinst->uwc_bar_start = res->start;

        res = &pdev->resource[2];
        vinst->paste_base_addr = res->start;

        res = &pdev->resource[3];
        if (res->end > 62) {
                pr_err("Bad 'paste_win_id_shift' in DT, %llx\n", res->end);
                goto free_vinst;
        }

        vinst->paste_win_id_shift = 63 - res->end;

        hwirq = xive_native_alloc_irq_on_chip(chipid);
        if (!hwirq) {
                pr_err("Inst%d: Unable to allocate global irq for chip %d\n",
                                vinst->vas_id, chipid);
                return -ENOENT;
        }

        vinst->virq = irq_create_mapping(NULL, hwirq);
        if (!vinst->virq) {
                pr_err("Inst%d: Unable to map global irq %d\n",
                                vinst->vas_id, hwirq);
                return -EINVAL;
        }

        xd = irq_get_chip_data(vinst->virq);
        if (!xd) {
                pr_err("Inst%d: Invalid virq %d\n",
                                vinst->vas_id, vinst->virq);
                return -EINVAL;
        }

        vinst->irq_port = xd->trig_page;
        pr_devel("Initialized instance [%s, %d] paste_base 0x%llx paste_win_id_shift 0x%llx IRQ %d Port 0x%llx\n",
                        pdev->name, vasid, vinst->paste_base_addr,
                        vinst->paste_win_id_shift, vinst->virq,
                        vinst->irq_port);

        for_each_possible_cpu(cpu) {
                if (cpu_to_chip_id(cpu) == of_get_ibm_chip_id(dn))
                        per_cpu(cpu_vas_id, cpu) = vasid;
        }

        mutex_lock(&vas_mutex);
        list_add(&vinst->node, &vas_instances);
        mutex_unlock(&vas_mutex);

        spin_lock_init(&vinst->fault_lock);
        /*
         * IRQ and fault handling setup is needed only for user space
         * send windows.
         */
        if (vinst->virq) {
                rc = vas_irq_fault_window_setup(vinst);
                /*
                 * Fault window is used only for user space send windows.
                 * So if vinst->virq is NULL, tx_win_open returns -ENODEV
                 * for user space.
                 */
                if (rc)
                        vinst->virq = 0;
        }

        vas_instance_init_dbgdir(vinst);

        dev_set_drvdata(&pdev->dev, vinst);

        return 0;

free_vinst:
        kfree(vinst->name);
        kfree(vinst);
        return -ENODEV;

}

/*
 * Although this is read/used multiple times, it is written to only
 * during initialization.
 */
struct vas_instance *find_vas_instance(int vasid)
{
        struct list_head *ent;
        struct vas_instance *vinst;

        mutex_lock(&vas_mutex);

        if (vasid == -1)
                vasid = per_cpu(cpu_vas_id, smp_processor_id());

        list_for_each(ent, &vas_instances) {
                vinst = list_entry(ent, struct vas_instance, node);
                if (vinst->vas_id == vasid) {
                        mutex_unlock(&vas_mutex);
                        return vinst;
                }
        }
        mutex_unlock(&vas_mutex);

        pr_devel("Instance %d not found\n", vasid);
        return NULL;
}

int chip_to_vas_id(int chipid)
{
        int cpu;

        for_each_possible_cpu(cpu) {
                if (cpu_to_chip_id(cpu) == chipid)
                        return per_cpu(cpu_vas_id, cpu);
        }
        return -1;
}
EXPORT_SYMBOL(chip_to_vas_id);

static int vas_probe(struct platform_device *pdev)
{
        return init_vas_instance(pdev);
}

static const struct of_device_id powernv_vas_match[] = {
        { .compatible = "ibm,vas",},
        {},
};

static struct platform_driver vas_driver = {
        .driver = {
                .name = "vas",
                .of_match_table = powernv_vas_match,
        },
        .probe = vas_probe,
};

static int __init vas_init(void)
{
        int found = 0;
        struct device_node *dn;

        platform_driver_register(&vas_driver);

        for_each_compatible_node(dn, NULL, "ibm,vas") {
                of_platform_device_create(dn, NULL, NULL);
                found++;
        }

        if (!found) {
                platform_driver_unregister(&vas_driver);
                return -ENODEV;
        }

        pr_devel("Found %d instances\n", found);

        return 0;
}
device_initcall(vas_init);