// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2018-2020 Linaro Ltd.
 */

/* DOC: IPA Interrupts
 *
 * The IPA has an interrupt line distinct from the interrupt used by the GSI
 * code.  Whereas GSI interrupts are generally related to channel events (like
 * transfer completions), IPA interrupts are related to other events related
 * to the IPA.  Some of the IPA interrupts come from a microcontroller
 * embedded in the IPA.  Each IPA interrupt type can be both masked and
 * acknowledged independent of the others.
 *
 * Two of the IPA interrupts are initiated by the microcontroller.  A third
 * can be generated to signal the need for a wakeup/resume when an IPA
 * endpoint has been suspended.  There are other IPA events, but at this
 * time only these three are supported.
 */

#include <linux/types.h>
#include <linux/interrupt.h>

#include "ipa.h"
#include "ipa_clock.h"
#include "ipa_reg.h"
#include "ipa_endpoint.h"
#include "ipa_interrupt.h"

/**
 * struct ipa_interrupt - IPA interrupt information
 * @ipa:                IPA pointer
 * @irq:                Linux IRQ number used for IPA interrupts
 * @enabled:            Mask indicating which interrupts are enabled
 * @handler:            Array of handlers indexed by IPA interrupt ID
 */
struct ipa_interrupt {
        struct ipa *ipa;
        u32 irq;
        u32 enabled;
        ipa_irq_handler_t handler[IPA_IRQ_COUNT];
};

/* Returns true if the interrupt type is associated with the microcontroller */
static bool ipa_interrupt_uc(struct ipa_interrupt *interrupt, u32 irq_id)
{
        return irq_id == IPA_IRQ_UC_0 || irq_id == IPA_IRQ_UC_1;
}

/* Process a particular interrupt type that has been received */
static void ipa_interrupt_process(struct ipa_interrupt *interrupt, u32 irq_id)
{
        bool uc_irq = ipa_interrupt_uc(interrupt, irq_id);
        struct ipa *ipa = interrupt->ipa;
        u32 mask = BIT(irq_id);

        /* For microcontroller interrupts, clear the interrupt right away,
         * "to avoid clearing unhandled interrupts."
         */
        if (uc_irq)
                iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);

        if (irq_id < IPA_IRQ_COUNT && interrupt->handler[irq_id])
                interrupt->handler[irq_id](interrupt->ipa, irq_id);

        /* Clearing the SUSPEND_TX interrupt also clears the register
         * that tells us which suspended endpoint(s) caused the interrupt,
         * so defer clearing until after the handler has been called.
         */
        if (!uc_irq)
                iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);
}

/* Process all IPA interrupt types that have been signaled */
static void ipa_interrupt_process_all(struct ipa_interrupt *interrupt)
{
        struct ipa *ipa = interrupt->ipa;
        u32 enabled = interrupt->enabled;
        u32 mask;

        /* The status register indicates which conditions are present,
         * including conditions whose interrupt is not enabled.  Handle
         * only the enabled ones.
         */
        mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
        while ((mask &= enabled)) {
                do {
                        u32 irq_id = __ffs(mask);

                        mask ^= BIT(irq_id);

                        ipa_interrupt_process(interrupt, irq_id);
                } while (mask);
                mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
        }
}

/* Threaded part of the IPA IRQ handler */
static irqreturn_t ipa_isr_thread(int irq, void *dev_id)
{
        struct ipa_interrupt *interrupt = dev_id;

        ipa_clock_get(interrupt->ipa);

        ipa_interrupt_process_all(interrupt);

        ipa_clock_put(interrupt->ipa);

        return IRQ_HANDLED;
}

/* Hard part (i.e., "real" IRQ handler) of the IRQ handler */
static irqreturn_t ipa_isr(int irq, void *dev_id)
{
        struct ipa_interrupt *interrupt = dev_id;
        struct ipa *ipa = interrupt->ipa;
        u32 mask;

        mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
        if (mask & interrupt->enabled)
                return IRQ_WAKE_THREAD;

        /* Nothing in the mask was supposed to cause an interrupt */
        iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);

        dev_err(&ipa->pdev->dev, "%s: unexpected interrupt, mask 0x%08x\n",
                __func__, mask);

        return IRQ_HANDLED;
}

/* Common function used to enable/disable TX_SUSPEND for an endpoint */
static void ipa_interrupt_suspend_control(struct ipa_interrupt *interrupt,
                                          u32 endpoint_id, bool enable)
{
        struct ipa *ipa = interrupt->ipa;
        u32 mask = BIT(endpoint_id);
        u32 val;

        /* assert(mask & ipa->available); */
        val = ioread32(ipa->reg_virt + IPA_REG_SUSPEND_IRQ_EN_OFFSET);
        if (enable)
                val |= mask;
        else
                val &= ~mask;
        iowrite32(val, ipa->reg_virt + IPA_REG_SUSPEND_IRQ_EN_OFFSET);
}

/* Enable TX_SUSPEND for an endpoint */
void
ipa_interrupt_suspend_enable(struct ipa_interrupt *interrupt, u32 endpoint_id)
{
        ipa_interrupt_suspend_control(interrupt, endpoint_id, true);
}

/* Disable TX_SUSPEND for an endpoint */
void
ipa_interrupt_suspend_disable(struct ipa_interrupt *interrupt, u32 endpoint_id)
{
        ipa_interrupt_suspend_control(interrupt, endpoint_id, false);
}

/* Clear the suspend interrupt for all endpoints that signaled it */
void ipa_interrupt_suspend_clear_all(struct ipa_interrupt *interrupt)
{
        struct ipa *ipa = interrupt->ipa;
        u32 val;

        val = ioread32(ipa->reg_virt + IPA_REG_IRQ_SUSPEND_INFO_OFFSET);
        iowrite32(val, ipa->reg_virt + IPA_REG_SUSPEND_IRQ_CLR_OFFSET);
}

/* Simulate arrival of an IPA TX_SUSPEND interrupt */
void ipa_interrupt_simulate_suspend(struct ipa_interrupt *interrupt)
{
        ipa_interrupt_process(interrupt, IPA_IRQ_TX_SUSPEND);
}

/* Add a handler for an IPA interrupt */
void ipa_interrupt_add(struct ipa_interrupt *interrupt,
                       enum ipa_irq_id ipa_irq, ipa_irq_handler_t handler)
{
        struct ipa *ipa = interrupt->ipa;

        /* assert(ipa_irq < IPA_IRQ_COUNT); */
        interrupt->handler[ipa_irq] = handler;

        /* Update the IPA interrupt mask to enable it */
        interrupt->enabled |= BIT(ipa_irq);
        iowrite32(interrupt->enabled, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);
}

/* Remove the handler for an IPA interrupt type */
void
ipa_interrupt_remove(struct ipa_interrupt *interrupt, enum ipa_irq_id ipa_irq)
{
        struct ipa *ipa = interrupt->ipa;

        /* assert(ipa_irq < IPA_IRQ_COUNT); */
        /* Update the IPA interrupt mask to disable it */
        interrupt->enabled &= ~BIT(ipa_irq);
        iowrite32(interrupt->enabled, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);

        interrupt->handler[ipa_irq] = NULL;
}

/* Set up the IPA interrupt framework */
struct ipa_interrupt *ipa_interrupt_setup(struct ipa *ipa)
{
        struct device *dev = &ipa->pdev->dev;
        struct ipa_interrupt *interrupt;
        unsigned int irq;
        int ret;

        ret = platform_get_irq_byname(ipa->pdev, "ipa");
        if (ret <= 0) {
                dev_err(dev, "DT error %d getting \"ipa\" IRQ property\n",
                        ret);
                return ERR_PTR(ret ? : -EINVAL);
        }
        irq = ret;

        interrupt = kzalloc(sizeof(*interrupt), GFP_KERNEL);
        if (!interrupt)
                return ERR_PTR(-ENOMEM);
        interrupt->ipa = ipa;
        interrupt->irq = irq;

        /* Start with all IPA interrupts disabled */
        iowrite32(0, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);

        ret = request_threaded_irq(irq, ipa_isr, ipa_isr_thread, IRQF_ONESHOT,
                                   "ipa", interrupt);
        if (ret) {
                dev_err(dev, "error %d requesting \"ipa\" IRQ\n", ret);
                goto err_kfree;
        }

        return interrupt;

err_kfree:
        kfree(interrupt);

        return ERR_PTR(ret);
}

/* Tear down the IPA interrupt framework */
void ipa_interrupt_teardown(struct ipa_interrupt *interrupt)
{
        free_irq(interrupt->irq, interrupt);
        kfree(interrupt);
}