// SPDX-License-Identifier: GPL-2.0
/*
 * Texas Instruments' K3 Interrupt Aggregator irqchip driver
 *
 * Copyright (C) 2018-2019 Texas Instruments Incorporated - http://www.ti.com/
 *      Lokesh Vutla <lokeshvutla@ti.com>
 */

#include <linux/err.h>
#include <linux/io.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <linux/msi.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/soc/ti/ti_sci_inta_msi.h>
#include <linux/soc/ti/ti_sci_protocol.h>
#include <asm-generic/msi.h>

#define TI_SCI_DEV_ID_MASK      0xffff
#define TI_SCI_DEV_ID_SHIFT     16
#define TI_SCI_IRQ_ID_MASK      0xffff
#define TI_SCI_IRQ_ID_SHIFT     0
#define HWIRQ_TO_DEVID(hwirq)   (((hwirq) >> (TI_SCI_DEV_ID_SHIFT)) & \
                                 (TI_SCI_DEV_ID_MASK))
#define HWIRQ_TO_IRQID(hwirq)   ((hwirq) & (TI_SCI_IRQ_ID_MASK))
#define TO_HWIRQ(dev, index)    ((((dev) & TI_SCI_DEV_ID_MASK) << \
                                 TI_SCI_DEV_ID_SHIFT) | \
                                ((index) & TI_SCI_IRQ_ID_MASK))

#define MAX_EVENTS_PER_VINT     64
#define VINT_ENABLE_SET_OFFSET  0x0
#define VINT_ENABLE_CLR_OFFSET  0x8
#define VINT_STATUS_OFFSET      0x18

/**
 * struct ti_sci_inta_event_desc - Description of an event coming to
 *                                 Interrupt Aggregator. This serves
 *                                 as a mapping table for global event,
 *                                 hwirq and vint bit.
 * @global_event:       Global event number corresponding to this event
 * @hwirq:              Hwirq of the incoming interrupt
 * @vint_bit:           Corresponding vint bit to which this event is attached.
 */
struct ti_sci_inta_event_desc {
        u16 global_event;
        u32 hwirq;
        u8 vint_bit;
};

/**
 * struct ti_sci_inta_vint_desc - Description of a virtual interrupt coming out
 *                                of Interrupt Aggregator.
 * @domain:             Pointer to IRQ domain to which this vint belongs.
 * @list:               List entry for the vint list
 * @event_map:          Bitmap to manage the allocation of events to vint.
 * @events:             Array of event descriptors assigned to this vint.
 * @parent_virq:        Linux IRQ number that gets attached to parent
 * @vint_id:            TISCI vint ID
 */
struct ti_sci_inta_vint_desc {
        struct irq_domain *domain;
        struct list_head list;
        DECLARE_BITMAP(event_map, MAX_EVENTS_PER_VINT);
        struct ti_sci_inta_event_desc events[MAX_EVENTS_PER_VINT];
        unsigned int parent_virq;
        u16 vint_id;
};

/**
 * struct ti_sci_inta_irq_domain - Structure representing a TISCI based
 *                                 Interrupt Aggregator IRQ domain.
 * @sci:                Pointer to TISCI handle
 * @vint:               TISCI resource pointer representing IA inerrupts.
 * @global_event:       TISCI resource pointer representing global events.
 * @vint_list:          List of the vints active in the system
 * @vint_mutex:         Mutex to protect vint_list
 * @base:               Base address of the memory mapped IO registers
 * @pdev:               Pointer to platform device.
 */
struct ti_sci_inta_irq_domain {
        const struct ti_sci_handle *sci;
        struct ti_sci_resource *vint;
        struct ti_sci_resource *global_event;
        struct list_head vint_list;
        /* Mutex to protect vint list */
        struct mutex vint_mutex;
        void __iomem *base;
        struct platform_device *pdev;
};

#define to_vint_desc(e, i) container_of(e, struct ti_sci_inta_vint_desc, \
                                        events[i])

/**
 * ti_sci_inta_irq_handler() - Chained IRQ handler for the vint irqs
 * @desc:       Pointer to irq_desc corresponding to the irq
 */
static void ti_sci_inta_irq_handler(struct irq_desc *desc)
{
        struct ti_sci_inta_vint_desc *vint_desc;
        struct ti_sci_inta_irq_domain *inta;
        struct irq_domain *domain;
        unsigned int virq, bit;
        unsigned long val;

        vint_desc = irq_desc_get_handler_data(desc);
        domain = vint_desc->domain;
        inta = domain->host_data;

        chained_irq_enter(irq_desc_get_chip(desc), desc);

        val = readq_relaxed(inta->base + vint_desc->vint_id * 0x1000 +
                            VINT_STATUS_OFFSET);

        for_each_set_bit(bit, &val, MAX_EVENTS_PER_VINT) {
                virq = irq_find_mapping(domain, vint_desc->events[bit].hwirq);
                if (virq)
                        generic_handle_irq(virq);
        }

        chained_irq_exit(irq_desc_get_chip(desc), desc);
}

/**
 * ti_sci_inta_alloc_parent_irq() - Allocate parent irq to Interrupt aggregator
 * @domain:     IRQ domain corresponding to Interrupt Aggregator
 *
 * Return 0 if all went well else corresponding error value.
 */
static struct ti_sci_inta_vint_desc *ti_sci_inta_alloc_parent_irq(struct irq_domain *domain)
{
        struct ti_sci_inta_irq_domain *inta = domain->host_data;
        struct ti_sci_inta_vint_desc *vint_desc;
        struct irq_fwspec parent_fwspec;
        unsigned int parent_virq;
        u16 vint_id;

        vint_id = ti_sci_get_free_resource(inta->vint);
        if (vint_id == TI_SCI_RESOURCE_NULL)
                return ERR_PTR(-EINVAL);

        vint_desc = kzalloc(sizeof(*vint_desc), GFP_KERNEL);
        if (!vint_desc)
                return ERR_PTR(-ENOMEM);

        vint_desc->domain = domain;
        vint_desc->vint_id = vint_id;
        INIT_LIST_HEAD(&vint_desc->list);

        parent_fwspec.fwnode = of_node_to_fwnode(of_irq_find_parent(dev_of_node(&inta->pdev->dev)));
        parent_fwspec.param_count = 2;
        parent_fwspec.param[0] = inta->pdev->id;
        parent_fwspec.param[1] = vint_desc->vint_id;

        parent_virq = irq_create_fwspec_mapping(&parent_fwspec);
        if (parent_virq == 0) {
                kfree(vint_desc);
                return ERR_PTR(-EINVAL);
        }
        vint_desc->parent_virq = parent_virq;

        list_add_tail(&vint_desc->list, &inta->vint_list);
        irq_set_chained_handler_and_data(vint_desc->parent_virq,
                                         ti_sci_inta_irq_handler, vint_desc);

        return vint_desc;
}

/**
 * ti_sci_inta_alloc_event() - Attach an event to a IA vint.
 * @vint_desc:  Pointer to vint_desc to which the event gets attached
 * @free_bit:   Bit inside vint to which event gets attached
 * @hwirq:      hwirq of the input event
 *
 * Return event_desc pointer if all went ok else appropriate error value.
 */
static struct ti_sci_inta_event_desc *ti_sci_inta_alloc_event(struct ti_sci_inta_vint_desc *vint_desc,
                                                              u16 free_bit,
                                                              u32 hwirq)
{
        struct ti_sci_inta_irq_domain *inta = vint_desc->domain->host_data;
        struct ti_sci_inta_event_desc *event_desc;
        u16 dev_id, dev_index;
        int err;

        dev_id = HWIRQ_TO_DEVID(hwirq);
        dev_index = HWIRQ_TO_IRQID(hwirq);

        event_desc = &vint_desc->events[free_bit];
        event_desc->hwirq = hwirq;
        event_desc->vint_bit = free_bit;
        event_desc->global_event = ti_sci_get_free_resource(inta->global_event);
        if (event_desc->global_event == TI_SCI_RESOURCE_NULL)
                return ERR_PTR(-EINVAL);

        err = inta->sci->ops.rm_irq_ops.set_event_map(inta->sci,
                                                      dev_id, dev_index,
                                                      inta->pdev->id,
                                                      vint_desc->vint_id,
                                                      event_desc->global_event,
                                                      free_bit);
        if (err)
                goto free_global_event;

        return event_desc;
free_global_event:
        ti_sci_release_resource(inta->global_event, event_desc->global_event);
        return ERR_PTR(err);
}

/**
 * ti_sci_inta_alloc_irq() -  Allocate an irq within INTA domain
 * @domain:     irq_domain pointer corresponding to INTA
 * @hwirq:      hwirq of the input event
 *
 * Note: Allocation happens in the following manner:
 *      - Find a free bit available in any of the vints available in the list.
 *      - If not found, allocate a vint from the vint pool
 *      - Attach the free bit to input hwirq.
 * Return event_desc if all went ok else appropriate error value.
 */
static struct ti_sci_inta_event_desc *ti_sci_inta_alloc_irq(struct irq_domain *domain,
                                                            u32 hwirq)
{
        struct ti_sci_inta_irq_domain *inta = domain->host_data;
        struct ti_sci_inta_vint_desc *vint_desc = NULL;
        struct ti_sci_inta_event_desc *event_desc;
        u16 free_bit;

        mutex_lock(&inta->vint_mutex);
        list_for_each_entry(vint_desc, &inta->vint_list, list) {
                free_bit = find_first_zero_bit(vint_desc->event_map,
                                               MAX_EVENTS_PER_VINT);
                if (free_bit != MAX_EVENTS_PER_VINT) {
                        set_bit(free_bit, vint_desc->event_map);
                        goto alloc_event;
                }
        }

        /* No free bits available. Allocate a new vint */
        vint_desc = ti_sci_inta_alloc_parent_irq(domain);
        if (IS_ERR(vint_desc)) {
                mutex_unlock(&inta->vint_mutex);
                return ERR_PTR(PTR_ERR(vint_desc));
        }

        free_bit = find_first_zero_bit(vint_desc->event_map,
                                       MAX_EVENTS_PER_VINT);
        set_bit(free_bit, vint_desc->event_map);

alloc_event:
        event_desc = ti_sci_inta_alloc_event(vint_desc, free_bit, hwirq);
        if (IS_ERR(event_desc))
                clear_bit(free_bit, vint_desc->event_map);

        mutex_unlock(&inta->vint_mutex);
        return event_desc;
}

/**
 * ti_sci_inta_free_parent_irq() - Free a parent irq to INTA
 * @inta:       Pointer to inta domain.
 * @vint_desc:  Pointer to vint_desc that needs to be freed.
 */
static void ti_sci_inta_free_parent_irq(struct ti_sci_inta_irq_domain *inta,
                                        struct ti_sci_inta_vint_desc *vint_desc)
{
        if (find_first_bit(vint_desc->event_map, MAX_EVENTS_PER_VINT) == MAX_EVENTS_PER_VINT) {
                list_del(&vint_desc->list);
                ti_sci_release_resource(inta->vint, vint_desc->vint_id);
                irq_dispose_mapping(vint_desc->parent_virq);
                kfree(vint_desc);
        }
}

/**
 * ti_sci_inta_free_irq() - Free an IRQ within INTA domain
 * @event_desc: Pointer to event_desc that needs to be freed.
 * @hwirq:      Hwirq number within INTA domain that needs to be freed
 */
static void ti_sci_inta_free_irq(struct ti_sci_inta_event_desc *event_desc,
                                 u32 hwirq)
{
        struct ti_sci_inta_vint_desc *vint_desc;
        struct ti_sci_inta_irq_domain *inta;

        vint_desc = to_vint_desc(event_desc, event_desc->vint_bit);
        inta = vint_desc->domain->host_data;
        /* free event irq */
        mutex_lock(&inta->vint_mutex);
        inta->sci->ops.rm_irq_ops.free_event_map(inta->sci,
                                                 HWIRQ_TO_DEVID(hwirq),
                                                 HWIRQ_TO_IRQID(hwirq),
                                                 inta->pdev->id,
                                                 vint_desc->vint_id,
                                                 event_desc->global_event,
                                                 event_desc->vint_bit);

        clear_bit(event_desc->vint_bit, vint_desc->event_map);
        ti_sci_release_resource(inta->global_event, event_desc->global_event);
        event_desc->global_event = TI_SCI_RESOURCE_NULL;
        event_desc->hwirq = 0;

        ti_sci_inta_free_parent_irq(inta, vint_desc);
        mutex_unlock(&inta->vint_mutex);
}

/**
 * ti_sci_inta_request_resources() - Allocate resources for input irq
 * @data: Pointer to corresponding irq_data
 *
 * Note: This is the core api where the actual allocation happens for input
 *       hwirq. This allocation involves creating a parent irq for vint.
 *       If this is done in irq_domain_ops.alloc() then a deadlock is reached
 *       for allocation. So this allocation is being done in request_resources()
 *
 * Return: 0 if all went well else corresponding error.
 */
static int ti_sci_inta_request_resources(struct irq_data *data)
{
        struct ti_sci_inta_event_desc *event_desc;

        event_desc = ti_sci_inta_alloc_irq(data->domain, data->hwirq);
        if (IS_ERR(event_desc))
                return PTR_ERR(event_desc);

        data->chip_data = event_desc;

        return 0;
}

/**
 * ti_sci_inta_release_resources - Release resources for input irq
 * @data: Pointer to corresponding irq_data
 *
 * Note: Corresponding to request_resources(), all the unmapping and deletion
 *       of parent vint irqs happens in this api.
 */
static void ti_sci_inta_release_resources(struct irq_data *data)
{
        struct ti_sci_inta_event_desc *event_desc;

        event_desc = irq_data_get_irq_chip_data(data);
        ti_sci_inta_free_irq(event_desc, data->hwirq);
}

/**
 * ti_sci_inta_manage_event() - Control the event based on the offset
 * @data:       Pointer to corresponding irq_data
 * @offset:     register offset using which event is controlled.
 */
static void ti_sci_inta_manage_event(struct irq_data *data, u32 offset)
{
        struct ti_sci_inta_event_desc *event_desc;
        struct ti_sci_inta_vint_desc *vint_desc;
        struct ti_sci_inta_irq_domain *inta;

        event_desc = irq_data_get_irq_chip_data(data);
        vint_desc = to_vint_desc(event_desc, event_desc->vint_bit);
        inta = data->domain->host_data;

        writeq_relaxed(BIT(event_desc->vint_bit),
                       inta->base + vint_desc->vint_id * 0x1000 + offset);
}

/**
 * ti_sci_inta_mask_irq() - Mask an event
 * @data:       Pointer to corresponding irq_data
 */
static void ti_sci_inta_mask_irq(struct irq_data *data)
{
        ti_sci_inta_manage_event(data, VINT_ENABLE_CLR_OFFSET);
}

/**
 * ti_sci_inta_unmask_irq() - Unmask an event
 * @data:       Pointer to corresponding irq_data
 */
static void ti_sci_inta_unmask_irq(struct irq_data *data)
{
        ti_sci_inta_manage_event(data, VINT_ENABLE_SET_OFFSET);
}

/**
 * ti_sci_inta_ack_irq() - Ack an event
 * @data:       Pointer to corresponding irq_data
 */
static void ti_sci_inta_ack_irq(struct irq_data *data)
{
        /*
         * Do not clear the event if hardware is capable of sending
         * a down event.
         */
        if (irqd_get_trigger_type(data) != IRQF_TRIGGER_HIGH)
                ti_sci_inta_manage_event(data, VINT_STATUS_OFFSET);
}

static int ti_sci_inta_set_affinity(struct irq_data *d,
                                    const struct cpumask *mask_val, bool force)
{
        return -EINVAL;
}

/**
 * ti_sci_inta_set_type() - Update the trigger type of the irq.
 * @data:       Pointer to corresponding irq_data
 * @type:       Trigger type as specified by user
 *
 * Note: This updates the handle_irq callback for level msi.
 *
 * Return 0 if all went well else appropriate error.
 */
static int ti_sci_inta_set_type(struct irq_data *data, unsigned int type)
{
        /*
         * .alloc default sets handle_edge_irq. But if the user specifies
         * that IRQ is level MSI, then update the handle to handle_level_irq
         */
        switch (type & IRQ_TYPE_SENSE_MASK) {
        case IRQF_TRIGGER_HIGH:
                irq_set_handler_locked(data, handle_level_irq);
                return 0;
        case IRQF_TRIGGER_RISING:
                return 0;
        default:
                return -EINVAL;
        }

        return -EINVAL;
}

static struct irq_chip ti_sci_inta_irq_chip = {
        .name                   = "INTA",
        .irq_ack                = ti_sci_inta_ack_irq,
        .irq_mask               = ti_sci_inta_mask_irq,
        .irq_set_type           = ti_sci_inta_set_type,
        .irq_unmask             = ti_sci_inta_unmask_irq,
        .irq_set_affinity       = ti_sci_inta_set_affinity,
        .irq_request_resources  = ti_sci_inta_request_resources,
        .irq_release_resources  = ti_sci_inta_release_resources,
};

/**
 * ti_sci_inta_irq_domain_free() - Free an IRQ from the IRQ domain
 * @domain:     Domain to which the irqs belong
 * @virq:       base linux virtual IRQ to be freed.
 * @nr_irqs:    Number of continuous irqs to be freed
 */
static void ti_sci_inta_irq_domain_free(struct irq_domain *domain,
                                        unsigned int virq, unsigned int nr_irqs)
{
        struct irq_data *data = irq_domain_get_irq_data(domain, virq);

        irq_domain_reset_irq_data(data);
}

/**
 * ti_sci_inta_irq_domain_alloc() - Allocate Interrupt aggregator IRQs
 * @domain:     Point to the interrupt aggregator IRQ domain
 * @virq:       Corresponding Linux virtual IRQ number
 * @nr_irqs:    Continuous irqs to be allocated
 * @data:       Pointer to firmware specifier
 *
 * No actual allocation happens here.
 *
 * Return 0 if all went well else appropriate error value.
 */
static int ti_sci_inta_irq_domain_alloc(struct irq_domain *domain,
                                        unsigned int virq, unsigned int nr_irqs,
                                        void *data)
{
        msi_alloc_info_t *arg = data;

        irq_domain_set_info(domain, virq, arg->hwirq, &ti_sci_inta_irq_chip,
                            NULL, handle_edge_irq, NULL, NULL);

        return 0;
}

static const struct irq_domain_ops ti_sci_inta_irq_domain_ops = {
        .free           = ti_sci_inta_irq_domain_free,
        .alloc          = ti_sci_inta_irq_domain_alloc,
};

static struct irq_chip ti_sci_inta_msi_irq_chip = {
        .name                   = "MSI-INTA",
        .flags                  = IRQCHIP_SUPPORTS_LEVEL_MSI,
};

static void ti_sci_inta_msi_set_desc(msi_alloc_info_t *arg,
                                     struct msi_desc *desc)
{
        struct platform_device *pdev = to_platform_device(desc->dev);

        arg->desc = desc;
        arg->hwirq = TO_HWIRQ(pdev->id, desc->inta.dev_index);
}

static struct msi_domain_ops ti_sci_inta_msi_ops = {
        .set_desc       = ti_sci_inta_msi_set_desc,
};

static struct msi_domain_info ti_sci_inta_msi_domain_info = {
        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
                   MSI_FLAG_LEVEL_CAPABLE),
        .ops    = &ti_sci_inta_msi_ops,
        .chip   = &ti_sci_inta_msi_irq_chip,
};

static int ti_sci_inta_irq_domain_probe(struct platform_device *pdev)
{
        struct irq_domain *parent_domain, *domain, *msi_domain;
        struct device_node *parent_node, *node;
        struct ti_sci_inta_irq_domain *inta;
        struct device *dev = &pdev->dev;
        struct resource *res;
        int ret;

        node = dev_of_node(dev);
        parent_node = of_irq_find_parent(node);
        if (!parent_node) {
                dev_err(dev, "Failed to get IRQ parent node\n");
                return -ENODEV;
        }

        parent_domain = irq_find_host(parent_node);
        if (!parent_domain)
                return -EPROBE_DEFER;

        inta = devm_kzalloc(dev, sizeof(*inta), GFP_KERNEL);
        if (!inta)
                return -ENOMEM;

        inta->pdev = pdev;
        inta->sci = devm_ti_sci_get_by_phandle(dev, "ti,sci");
        if (IS_ERR(inta->sci)) {
                ret = PTR_ERR(inta->sci);
                if (ret != -EPROBE_DEFER)
                        dev_err(dev, "ti,sci read fail %d\n", ret);
                inta->sci = NULL;
                return ret;
        }

        ret = of_property_read_u32(dev->of_node, "ti,sci-dev-id", &pdev->id);
        if (ret) {
                dev_err(dev, "missing 'ti,sci-dev-id' property\n");
                return -EINVAL;
        }

        inta->vint = devm_ti_sci_get_of_resource(inta->sci, dev, pdev->id,
                                                 "ti,sci-rm-range-vint");
        if (IS_ERR(inta->vint)) {
                dev_err(dev, "VINT resource allocation failed\n");
                return PTR_ERR(inta->vint);
        }

        inta->global_event = devm_ti_sci_get_of_resource(inta->sci, dev, pdev->id,
                                                "ti,sci-rm-range-global-event");
        if (IS_ERR(inta->global_event)) {
                dev_err(dev, "Global event resource allocation failed\n");
                return PTR_ERR(inta->global_event);
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        inta->base = devm_ioremap_resource(dev, res);
        if (IS_ERR(inta->base))
                return -ENODEV;

        domain = irq_domain_add_linear(dev_of_node(dev),
                                       ti_sci_get_num_resources(inta->vint),
                                       &ti_sci_inta_irq_domain_ops, inta);
        if (!domain) {
                dev_err(dev, "Failed to allocate IRQ domain\n");
                return -ENOMEM;
        }

        msi_domain = ti_sci_inta_msi_create_irq_domain(of_node_to_fwnode(node),
                                                &ti_sci_inta_msi_domain_info,
                                                domain);
        if (!msi_domain) {
                irq_domain_remove(domain);
                dev_err(dev, "Failed to allocate msi domain\n");
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&inta->vint_list);
        mutex_init(&inta->vint_mutex);

        return 0;
}

static const struct of_device_id ti_sci_inta_irq_domain_of_match[] = {
        { .compatible = "ti,sci-inta", },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, ti_sci_inta_irq_domain_of_match);

static struct platform_driver ti_sci_inta_irq_domain_driver = {
        .probe = ti_sci_inta_irq_domain_probe,
        .driver = {
                .name = "ti-sci-inta",
                .of_match_table = ti_sci_inta_irq_domain_of_match,
        },
};
module_platform_driver(ti_sci_inta_irq_domain_driver);

MODULE_AUTHOR("Lokesh Vutla <lokeshvutla@ticom>");
MODULE_DESCRIPTION("K3 Interrupt Aggregator driver over TI SCI protocol");
MODULE_LICENSE("GPL v2");