// SPDX-License-Identifier: GPL-2.0
/*
 * Xilinx Event Management Driver
 *
 *  Copyright (C) 2021 Xilinx, Inc.
 *
 *  Abhyuday Godhasara <abhyuday.godhasara@xilinx.com>
 */

#include <linux/cpuhotplug.h>
#include <linux/firmware/xlnx-event-manager.h>
#include <linux/firmware/xlnx-zynqmp.h>
#include <linux/hashtable.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

static DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number1);

static int virq_sgi;
static int event_manager_availability = -EACCES;

/* SGI number used for Event management driver */
#define XLNX_EVENT_SGI_NUM      (15)

/* Max number of driver can register for same event */
#define MAX_DRIVER_PER_EVENT    (10U)

/* Max HashMap Order for PM API feature check (1<<7 = 128) */
#define REGISTERED_DRIVER_MAX_ORDER     (7)

#define MAX_BITS        (32U) /* Number of bits available for error mask */

#define FIRMWARE_VERSION_MASK                   (0xFFFFU)
#define REGISTER_NOTIFIER_FIRMWARE_VERSION      (2U)

static DEFINE_HASHTABLE(reg_driver_map, REGISTERED_DRIVER_MAX_ORDER);
static int sgi_num = XLNX_EVENT_SGI_NUM;

/**
 * struct registered_event_data - Registered Event Data.
 * @key:                key is the combine id(Node-Id | Event-Id) of type u64
 *                      where upper u32 for Node-Id and lower u32 for Event-Id,
 *                      And this used as key to index into hashmap.
 * @agent_data:         Data passed back to handler function.
 * @cb_type:            Type of Api callback, like PM_NOTIFY_CB, etc.
 * @eve_cb:             Function pointer to store the callback function.
 * @wake:               If this flag set, firmware will wakeup processor if is
 *                      in sleep or power down state.
 * @hentry:             hlist_node that hooks this entry into hashtable.
 */
struct registered_event_data {
        u64 key;
        enum pm_api_cb_id cb_type;
        void *agent_data;

        event_cb_func_t eve_cb;
        bool wake;
        struct hlist_node hentry;
};

static bool xlnx_is_error_event(const u32 node_id)
{
        if (node_id == EVENT_ERROR_PMC_ERR1 ||
            node_id == EVENT_ERROR_PMC_ERR2 ||
            node_id == EVENT_ERROR_PSM_ERR1 ||
            node_id == EVENT_ERROR_PSM_ERR2)
                return true;

        return false;
}

static int xlnx_add_cb_for_notify_event(const u32 node_id, const u32 event, const bool wake,
                                        event_cb_func_t cb_fun, void *data)
{
        u64 key = 0;
        struct registered_event_data *eve_data;

        key = ((u64)node_id << 32U) | (u64)event;
        /* Check for existing entry in hash table for given key id */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, key) {
                if (eve_data->key == key) {
                        pr_err("Found as already registered\n");
                        return -EINVAL;
                }
        }

        /* Add new entry if not present */
        eve_data = kmalloc(sizeof(*eve_data), GFP_KERNEL);
        if (!eve_data)
                return -ENOMEM;

        eve_data->key = key;
        eve_data->cb_type = PM_NOTIFY_CB;
        eve_data->eve_cb = cb_fun;
        eve_data->wake = wake;
        eve_data->agent_data = data;

        hash_add(reg_driver_map, &eve_data->hentry, key);

        return 0;
}

static int xlnx_add_cb_for_suspend(event_cb_func_t cb_fun, void *data)
{
        struct registered_event_data *eve_data;

        /* Check for existing entry in hash table for given cb_type */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, PM_INIT_SUSPEND_CB) {
                if (eve_data->cb_type == PM_INIT_SUSPEND_CB) {
                        pr_err("Found as already registered\n");
                        return -EINVAL;
                }
        }

        /* Add new entry if not present */
        eve_data = kmalloc(sizeof(*eve_data), GFP_KERNEL);
        if (!eve_data)
                return -ENOMEM;

        eve_data->key = 0;
        eve_data->cb_type = PM_INIT_SUSPEND_CB;
        eve_data->eve_cb = cb_fun;
        eve_data->agent_data = data;

        hash_add(reg_driver_map, &eve_data->hentry, PM_INIT_SUSPEND_CB);

        return 0;
}

static int xlnx_remove_cb_for_suspend(event_cb_func_t cb_fun)
{
        bool is_callback_found = false;
        struct registered_event_data *eve_data;

        /* Check for existing entry in hash table for given cb_type */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, PM_INIT_SUSPEND_CB) {
                if (eve_data->cb_type == PM_INIT_SUSPEND_CB &&
                    eve_data->eve_cb == cb_fun) {
                        is_callback_found = true;
                        /* remove an object from a hashtable */
                        hash_del(&eve_data->hentry);
                        kfree(eve_data);
                }
        }
        if (!is_callback_found) {
                pr_warn("Didn't find any registered callback for suspend event\n");
                return -EINVAL;
        }

        return 0;
}

static int xlnx_remove_cb_for_notify_event(const u32 node_id, const u32 event,
                                           event_cb_func_t cb_fun)
{
        bool is_callback_found = false;
        struct registered_event_data *eve_data;
        u64 key = ((u64)node_id << 32U) | (u64)event;

        /* Check for existing entry in hash table for given key id */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, key) {
                if (eve_data->key == key &&
                    eve_data->eve_cb == cb_fun) {
                        is_callback_found = true;
                        /* remove an object from a hashtable */
                        hash_del(&eve_data->hentry);
                        kfree(eve_data);
                }
        }
        if (!is_callback_found) {
                pr_warn("Didn't find any registered callback for 0x%x 0x%x\n",
                        node_id, event);
                return -EINVAL;
        }

        return 0;
}

/**
 * xlnx_register_event() - Register for the event.
 * @cb_type:    Type of callback from pm_api_cb_id,
 *                      PM_NOTIFY_CB - for Error Events,
 *                      PM_INIT_SUSPEND_CB - for suspend callback.
 * @node_id:    Node-Id related to event.
 * @event:      Event Mask for the Error Event.
 * @wake:       Flag specifying whether the subsystem should be woken upon
 *              event notification.
 * @cb_fun:     Function pointer to store the callback function.
 * @data:       Pointer for the driver instance.
 *
 * Return:      Returns 0 on successful registration else error code.
 */
int xlnx_register_event(const enum pm_api_cb_id cb_type, const u32 node_id, const u32 event,
                        const bool wake, event_cb_func_t cb_fun, void *data)
{
        int ret = 0;
        u32 eve;
        int pos;

        if (event_manager_availability)
                return event_manager_availability;

        if (cb_type != PM_NOTIFY_CB && cb_type != PM_INIT_SUSPEND_CB) {
                pr_err("%s() Unsupported Callback 0x%x\n", __func__, cb_type);
                return -EINVAL;
        }

        if (!cb_fun)
                return -EFAULT;

        if (cb_type == PM_INIT_SUSPEND_CB) {
                ret = xlnx_add_cb_for_suspend(cb_fun, data);
        } else {
                if (!xlnx_is_error_event(node_id)) {
                        /* Add entry for Node-Id/Event in hash table */
                        ret = xlnx_add_cb_for_notify_event(node_id, event, wake, cb_fun, data);
                } else {
                        /* Add into Hash table */
                        for (pos = 0; pos < MAX_BITS; pos++) {
                                eve = event & (1 << pos);
                                if (!eve)
                                        continue;

                                /* Add entry for Node-Id/Eve in hash table */
                                ret = xlnx_add_cb_for_notify_event(node_id, eve, wake, cb_fun,
                                                                   data);
                                /* Break the loop if got error */
                                if (ret)
                                        break;
                        }
                        if (ret) {
                                /* Skip the Event for which got the error */
                                pos--;
                                /* Remove registered(during this call) event from hash table */
                                for ( ; pos >= 0; pos--) {
                                        eve = event & (1 << pos);
                                        if (!eve)
                                                continue;
                                        xlnx_remove_cb_for_notify_event(node_id, eve, cb_fun);
                                }
                        }
                }

                if (ret) {
                        pr_err("%s() failed for 0x%x and 0x%x: %d\r\n", __func__, node_id,
                               event, ret);
                        return ret;
                }

                /* Register for Node-Id/Event combination in firmware */
                ret = zynqmp_pm_register_notifier(node_id, event, wake, true);
                if (ret) {
                        pr_err("%s() failed for 0x%x and 0x%x: %d\r\n", __func__, node_id,
                               event, ret);
                        /* Remove already registered event from hash table */
                        if (xlnx_is_error_event(node_id)) {
                                for (pos = 0; pos < MAX_BITS; pos++) {
                                        eve = event & (1 << pos);
                                        if (!eve)
                                                continue;
                                        xlnx_remove_cb_for_notify_event(node_id, eve, cb_fun);
                                }
                        } else {
                                xlnx_remove_cb_for_notify_event(node_id, event, cb_fun);
                        }
                        return ret;
                }
        }

        return ret;
}
EXPORT_SYMBOL_GPL(xlnx_register_event);

/**
 * xlnx_unregister_event() - Unregister for the event.
 * @cb_type:    Type of callback from pm_api_cb_id,
 *                      PM_NOTIFY_CB - for Error Events,
 *                      PM_INIT_SUSPEND_CB - for suspend callback.
 * @node_id:    Node-Id related to event.
 * @event:      Event Mask for the Error Event.
 * @cb_fun:     Function pointer of callback function.
 *
 * Return:      Returns 0 on successful unregistration else error code.
 */
int xlnx_unregister_event(const enum pm_api_cb_id cb_type, const u32 node_id, const u32 event,
                          event_cb_func_t cb_fun)
{
        int ret;
        u32 eve, pos;

        if (event_manager_availability)
                return event_manager_availability;

        if (cb_type != PM_NOTIFY_CB && cb_type != PM_INIT_SUSPEND_CB) {
                pr_err("%s() Unsupported Callback 0x%x\n", __func__, cb_type);
                return -EINVAL;
        }

        if (!cb_fun)
                return -EFAULT;

        if (cb_type == PM_INIT_SUSPEND_CB) {
                ret = xlnx_remove_cb_for_suspend(cb_fun);
        } else {
                /* Remove Node-Id/Event from hash table */
                if (!xlnx_is_error_event(node_id)) {
                        xlnx_remove_cb_for_notify_event(node_id, event, cb_fun);
                } else {
                        for (pos = 0; pos < MAX_BITS; pos++) {
                                eve = event & (1 << pos);
                                if (!eve)
                                        continue;

                                xlnx_remove_cb_for_notify_event(node_id, eve, cb_fun);
                        }
                }

                /* Un-register for Node-Id/Event combination */
                ret = zynqmp_pm_register_notifier(node_id, event, false, false);
                if (ret) {
                        pr_err("%s() failed for 0x%x and 0x%x: %d\n",
                               __func__, node_id, event, ret);
                        return ret;
                }
        }

        return ret;
}
EXPORT_SYMBOL_GPL(xlnx_unregister_event);

static void xlnx_call_suspend_cb_handler(const u32 *payload)
{
        bool is_callback_found = false;
        struct registered_event_data *eve_data;
        u32 cb_type = payload[0];

        /* Check for existing entry in hash table for given cb_type */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, cb_type) {
                if (eve_data->cb_type == cb_type) {
                        eve_data->eve_cb(&payload[0], eve_data->agent_data);
                        is_callback_found = true;
                }
        }
        if (!is_callback_found)
                pr_warn("Didn't find any registered callback for suspend event\n");
}

static void xlnx_call_notify_cb_handler(const u32 *payload)
{
        bool is_callback_found = false;
        struct registered_event_data *eve_data;
        u64 key = ((u64)payload[1] << 32U) | (u64)payload[2];
        int ret;

        /* Check for existing entry in hash table for given key id */
        hash_for_each_possible(reg_driver_map, eve_data, hentry, key) {
                if (eve_data->key == key) {
                        eve_data->eve_cb(&payload[0], eve_data->agent_data);
                        is_callback_found = true;

                        /* re register with firmware to get future events */
                        ret = zynqmp_pm_register_notifier(payload[1], payload[2],
                                                          eve_data->wake, true);
                        if (ret) {
                                pr_err("%s() failed for 0x%x and 0x%x: %d\r\n", __func__,
                                       payload[1], payload[2], ret);
                                /* Remove already registered event from hash table */
                                xlnx_remove_cb_for_notify_event(payload[1], payload[2],
                                                                eve_data->eve_cb);
                        }
                }
        }
        if (!is_callback_found)
                pr_warn("Didn't find any registered callback for 0x%x 0x%x\n",
                        payload[1], payload[2]);
}

static void xlnx_get_event_callback_data(u32 *buf)
{
        zynqmp_pm_invoke_fn(GET_CALLBACK_DATA, 0, 0, 0, 0, buf);
}

static irqreturn_t xlnx_event_handler(int irq, void *dev_id)
{
        u32 cb_type, node_id, event, pos;
        u32 payload[CB_MAX_PAYLOAD_SIZE] = {0};
        u32 event_data[CB_MAX_PAYLOAD_SIZE] = {0};

        /* Get event data */
        xlnx_get_event_callback_data(payload);

        /* First element is callback type, others are callback arguments */
        cb_type = payload[0];

        if (cb_type == PM_NOTIFY_CB) {
                node_id = payload[1];
                event = payload[2];
                if (!xlnx_is_error_event(node_id)) {
                        xlnx_call_notify_cb_handler(payload);
                } else {
                        /*
                         * Each call back function expecting payload as an input arguments.
                         * We can get multiple error events as in one call back through error
                         * mask. So payload[2] may can contain multiple error events.
                         * In reg_driver_map database we store data in the combination of single
                         * node_id-error combination.
                         * So coping the payload message into event_data and update the
                         * event_data[2] with Error Mask for single error event and use
                         * event_data as input argument for registered call back function.
                         *
                         */
                        memcpy(event_data, payload, (4 * CB_MAX_PAYLOAD_SIZE));
                        /* Support Multiple Error Event */
                        for (pos = 0; pos < MAX_BITS; pos++) {
                                if ((0 == (event & (1 << pos))))
                                        continue;
                                event_data[2] = (event & (1 << pos));
                                xlnx_call_notify_cb_handler(event_data);
                        }
                }
        } else if (cb_type == PM_INIT_SUSPEND_CB) {
                xlnx_call_suspend_cb_handler(payload);
        } else {
                pr_err("%s() Unsupported Callback %d\n", __func__, cb_type);
        }

        return IRQ_HANDLED;
}

static int xlnx_event_cpuhp_start(unsigned int cpu)
{
        enable_percpu_irq(virq_sgi, IRQ_TYPE_NONE);

        return 0;
}

static int xlnx_event_cpuhp_down(unsigned int cpu)
{
        disable_percpu_irq(virq_sgi);

        return 0;
}

static void xlnx_disable_percpu_irq(void *data)
{
        disable_percpu_irq(virq_sgi);
}

static int xlnx_event_init_sgi(struct platform_device *pdev)
{
        int ret = 0;
        int cpu = smp_processor_id();
        /*
         * IRQ related structures are used for the following:
         * for each SGI interrupt ensure its mapped by GIC IRQ domain
         * and that each corresponding linux IRQ for the HW IRQ has
         * a handler for when receiving an interrupt from the remote
         * processor.
         */
        struct irq_domain *domain;
        struct irq_fwspec sgi_fwspec;
        struct device_node *interrupt_parent = NULL;
        struct device *parent = pdev->dev.parent;

        /* Find GIC controller to map SGIs. */
        interrupt_parent = of_irq_find_parent(parent->of_node);
        if (!interrupt_parent) {
                dev_err(&pdev->dev, "Failed to find property for Interrupt parent\n");
                return -EINVAL;
        }

        /* Each SGI needs to be associated with GIC's IRQ domain. */
        domain = irq_find_host(interrupt_parent);
        of_node_put(interrupt_parent);

        /* Each mapping needs GIC domain when finding IRQ mapping. */
        sgi_fwspec.fwnode = domain->fwnode;

        /*
         * When irq domain looks at mapping each arg is as follows:
         * 3 args for: interrupt type (SGI), interrupt # (set later), type
         */
        sgi_fwspec.param_count = 1;

        /* Set SGI's hwirq */
        sgi_fwspec.param[0] = sgi_num;
        virq_sgi = irq_create_fwspec_mapping(&sgi_fwspec);

        per_cpu(cpu_number1, cpu) = cpu;
        ret = request_percpu_irq(virq_sgi, xlnx_event_handler, "xlnx_event_mgmt",
                                 &cpu_number1);
        WARN_ON(ret);
        if (ret) {
                irq_dispose_mapping(virq_sgi);
                return ret;
        }

        irq_to_desc(virq_sgi);
        irq_set_status_flags(virq_sgi, IRQ_PER_CPU);

        return ret;
}

static void xlnx_event_cleanup_sgi(struct platform_device *pdev)
{
        int cpu = smp_processor_id();

        per_cpu(cpu_number1, cpu) = cpu;

        cpuhp_remove_state(CPUHP_AP_ONLINE_DYN);

        on_each_cpu(xlnx_disable_percpu_irq, NULL, 1);

        irq_clear_status_flags(virq_sgi, IRQ_PER_CPU);
        free_percpu_irq(virq_sgi, &cpu_number1);
        irq_dispose_mapping(virq_sgi);
}

static int xlnx_event_manager_probe(struct platform_device *pdev)
{
        int ret;

        ret = zynqmp_pm_feature(PM_REGISTER_NOTIFIER);
        if (ret < 0) {
                dev_err(&pdev->dev, "Feature check failed with %d\n", ret);
                return ret;
        }

        if ((ret & FIRMWARE_VERSION_MASK) <
            REGISTER_NOTIFIER_FIRMWARE_VERSION) {
                dev_err(&pdev->dev, "Register notifier version error. Expected Firmware: v%d - Found: v%d\n",
                        REGISTER_NOTIFIER_FIRMWARE_VERSION,
                        ret & FIRMWARE_VERSION_MASK);
                return -EOPNOTSUPP;
        }

        /* Initialize the SGI */
        ret = xlnx_event_init_sgi(pdev);
        if (ret) {
                dev_err(&pdev->dev, "SGI Init has been failed with %d\n", ret);
                return ret;
        }

        /* Setup function for the CPU hot-plug cases */
        cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "soc/event:starting",
                          xlnx_event_cpuhp_start, xlnx_event_cpuhp_down);

        ret = zynqmp_pm_invoke_fn(PM_IOCTL, 0, IOCTL_REGISTER_SGI, sgi_num,
                                  0, NULL);
        if (ret) {
                dev_err(&pdev->dev, "SGI %d Registration over TF-A failed with %d\n", sgi_num, ret);
                xlnx_event_cleanup_sgi(pdev);
                return ret;
        }

        event_manager_availability = 0;

        dev_info(&pdev->dev, "SGI %d Registered over TF-A\n", sgi_num);
        dev_info(&pdev->dev, "Xilinx Event Management driver probed\n");

        return ret;
}

static int xlnx_event_manager_remove(struct platform_device *pdev)
{
        int i;
        struct registered_event_data *eve_data;
        struct hlist_node *tmp;
        int ret;

        hash_for_each_safe(reg_driver_map, i, tmp, eve_data, hentry) {
                hash_del(&eve_data->hentry);
                kfree(eve_data);
        }

        ret = zynqmp_pm_invoke_fn(PM_IOCTL, 0, IOCTL_REGISTER_SGI, 0, 1, NULL);
        if (ret)
                dev_err(&pdev->dev, "SGI unregistration over TF-A failed with %d\n", ret);

        xlnx_event_cleanup_sgi(pdev);

        event_manager_availability = -EACCES;

        return ret;
}

static struct platform_driver xlnx_event_manager_driver = {
        .probe = xlnx_event_manager_probe,
        .remove = xlnx_event_manager_remove,
        .driver = {
                .name = "xlnx_event_manager",
        },
};
module_param(sgi_num, uint, 0);
module_platform_driver(xlnx_event_manager_driver);