// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2018-2024 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/interrupt.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/pm_wakeirq.h>
#include <linux/types.h>

#include "ipa.h"
#include "ipa_endpoint.h"
#include "ipa_interrupt.h"
#include "ipa_power.h"
#include "ipa_reg.h"
#include "ipa_uc.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
 * @suspend_enabled:    Bitmap of endpoints with the SUSPEND interrupt enabled
 */
struct ipa_interrupt {
        struct ipa *ipa;
        u32 irq;
        u32 enabled;
        unsigned long *suspend_enabled;
};

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

        unit_count = DIV_ROUND_UP(ipa->endpoint_count, 32);
        for (unit = 0; unit < unit_count; unit++) {
                const struct reg *reg;
                u32 val;

                reg = ipa_reg(ipa, IRQ_SUSPEND_INFO);
                val = ioread32(ipa->reg_virt + reg_n_offset(reg, unit));

                /* SUSPEND interrupt status isn't cleared on IPA version 3.0 */
                if (!val || ipa->version == IPA_VERSION_3_0)
                        continue;

                reg = ipa_reg(ipa, IRQ_SUSPEND_CLR);
                iowrite32(val, ipa->reg_virt + reg_n_offset(reg, unit));
        }
}

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

        reg = ipa_reg(ipa, IPA_IRQ_CLR);
        offset = reg_offset(reg);

        switch (irq_id) {
        case IPA_IRQ_UC_0:
        case IPA_IRQ_UC_1:
                /* For microcontroller interrupts, clear the interrupt right
                 * away, "to avoid clearing unhandled interrupts."
                 */
                iowrite32(mask, ipa->reg_virt + offset);
                ipa_uc_interrupt_handler(ipa, irq_id);
                break;

        case IPA_IRQ_TX_SUSPEND:
                /* 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.
                 */
                ipa_interrupt_suspend_clear_all(interrupt);
                fallthrough;

        default:        /* Silently ignore (and clear) any other condition */
                iowrite32(mask, ipa->reg_virt + offset);
                break;
        }
}

/* IPA IRQ handler is threaded */
static irqreturn_t ipa_isr_thread(int irq, void *dev_id)
{
        struct ipa_interrupt *interrupt = dev_id;
        struct ipa *ipa = interrupt->ipa;
        u32 enabled = interrupt->enabled;
        struct device *dev = ipa->dev;
        const struct reg *reg;
        u32 pending;
        u32 offset;
        u32 mask;
        int ret;

        ret = pm_runtime_get_sync(dev);
        if (WARN_ON(ret < 0))
                goto out_power_put;

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

                        mask ^= BIT(irq_id);

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

        /* If any disabled interrupts are pending, clear them */
        if (pending) {
                dev_dbg(dev, "clearing disabled IPA interrupts 0x%08x\n",
                        pending);
                reg = ipa_reg(ipa, IPA_IRQ_CLR);
                iowrite32(pending, ipa->reg_virt + reg_offset(reg));
        }
out_power_put:
        (void)pm_runtime_put_autosuspend(dev);

        return IRQ_HANDLED;
}

static void ipa_interrupt_enabled_update(struct ipa *ipa)
{
        const struct reg *reg = ipa_reg(ipa, IPA_IRQ_EN);

        iowrite32(ipa->interrupt->enabled, ipa->reg_virt + reg_offset(reg));
}

/* Enable an IPA interrupt type */
void ipa_interrupt_enable(struct ipa *ipa, enum ipa_irq_id ipa_irq)
{
        /* Update the IPA interrupt mask to enable it */
        ipa->interrupt->enabled |= BIT(ipa_irq);
        ipa_interrupt_enabled_update(ipa);
}

/* Disable an IPA interrupt type */
void ipa_interrupt_disable(struct ipa *ipa, enum ipa_irq_id ipa_irq)
{
        /* Update the IPA interrupt mask to disable it */
        ipa->interrupt->enabled &= ~BIT(ipa_irq);
        ipa_interrupt_enabled_update(ipa);
}

void ipa_interrupt_irq_disable(struct ipa *ipa)
{
        disable_irq(ipa->interrupt->irq);
}

void ipa_interrupt_irq_enable(struct ipa *ipa)
{
        enable_irq(ipa->interrupt->irq);
}

/* 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 % 32);
        u32 unit = endpoint_id / 32;
        const struct reg *reg;
        unsigned long weight;
        u32 offset;
        u32 val;

        WARN_ON(!test_bit(endpoint_id, ipa->available));

        /* IPA version 3.0 does not support TX_SUSPEND interrupt control */
        if (ipa->version == IPA_VERSION_3_0)
                return;

        weight = bitmap_weight(interrupt->suspend_enabled, ipa->endpoint_count);
        if (weight == 1 && !enable)
                ipa_interrupt_disable(ipa, IPA_IRQ_TX_SUSPEND);

        reg = ipa_reg(ipa, IRQ_SUSPEND_EN);
        offset = reg_n_offset(reg, unit);
        val = ioread32(ipa->reg_virt + offset);

        if (enable)
                val |= mask;
        else
                val &= ~mask;
        __change_bit(endpoint_id, interrupt->suspend_enabled);

        iowrite32(val, ipa->reg_virt + offset);

        if (!weight && enable)
                ipa_interrupt_enable(ipa, IPA_IRQ_TX_SUSPEND);
}

/* 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);
}

/* 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);
}

/* Configure the IPA interrupt framework */
int ipa_interrupt_config(struct ipa *ipa)
{
        struct ipa_interrupt *interrupt = ipa->interrupt;
        unsigned int irq = interrupt->irq;
        struct device *dev = ipa->dev;
        const struct reg *reg;
        int ret;

        interrupt->ipa = ipa;

        /* Initially all IPA interrupt types are disabled */
        interrupt->enabled = 0;
        interrupt->suspend_enabled = bitmap_zalloc(ipa->endpoint_count,
                                                   GFP_KERNEL);
        if (!interrupt->suspend_enabled) {
                ret = -ENOMEM;
                goto err_kfree;
        }

        /* Disable IPA interrupt types */
        reg = ipa_reg(ipa, IPA_IRQ_EN);
        iowrite32(0, ipa->reg_virt + reg_offset(reg));

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

        ret = device_init_wakeup(dev, true);
        if (ret) {
                dev_err(dev, "error %d enabling wakeup\n", ret);
                goto err_free_irq;
        }

        ret = dev_pm_set_wake_irq(dev, irq);
        if (ret) {
                dev_err(dev, "error %d registering \"ipa\" IRQ as wakeirq\n",
                        ret);
                goto err_disable_wakeup;
        }

        ipa->interrupt = interrupt;

        return 0;

err_disable_wakeup:
        (void)device_init_wakeup(dev, false);
err_free_irq:
        free_irq(interrupt->irq, interrupt);
err_free_bitmap:
        bitmap_free(interrupt->suspend_enabled);
err_kfree:
        kfree(interrupt);

        return ret;
}

/* Inverse of ipa_interrupt_config() */
void ipa_interrupt_deconfig(struct ipa *ipa)
{
        struct ipa_interrupt *interrupt = ipa->interrupt;
        struct device *dev = ipa->dev;

        ipa->interrupt = NULL;

        dev_pm_clear_wake_irq(dev);
        (void)device_init_wakeup(dev, false);
        free_irq(interrupt->irq, interrupt);
        bitmap_free(interrupt->suspend_enabled);
}

/* Initialize the IPA interrupt structure */
struct ipa_interrupt *ipa_interrupt_init(struct platform_device *pdev)
{
        struct ipa_interrupt *interrupt;
        int irq;

        irq = platform_get_irq_byname(pdev, "ipa");
        if (irq <= 0)
                return ERR_PTR(irq ? : -EINVAL);

        interrupt = kzalloc_obj(*interrupt);
        if (!interrupt)
                return ERR_PTR(-ENOMEM);
        interrupt->irq = irq;

        return interrupt;
}

/* Inverse of ipa_interrupt_init() */
void ipa_interrupt_exit(struct ipa_interrupt *interrupt)
{
        kfree(interrupt);
}