// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2019-2020 Linaro Ltd.
 */

#include <linux/types.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/panic_notifier.h>
#include <linux/pm_runtime.h>
#include <linux/soc/qcom/smem.h>
#include <linux/soc/qcom/smem_state.h>

#include "ipa_smp2p.h"
#include "ipa.h"
#include "ipa_uc.h"

/**
 * DOC: IPA SMP2P communication with the modem
 *
 * SMP2P is a primitive communication mechanism available between the AP and
 * the modem.  The IPA driver uses this for two purposes:  to enable the modem
 * to state that the GSI hardware is ready to use; and to communicate the
 * state of IPA power in the event of a crash.
 *
 * GSI needs to have early initialization completed before it can be used.
 * This initialization is done either by Trust Zone or by the modem.  In the
 * latter case, the modem uses an SMP2P interrupt to tell the AP IPA driver
 * when the GSI is ready to use.
 *
 * The modem is also able to inquire about the current state of IPA
 * power by trigging another SMP2P interrupt to the AP.  We communicate
 * whether power is enabled using two SMP2P state bits--one to indicate
 * the power state (on or off), and a second to indicate the power state
 * bit is valid.  The modem will poll the valid bit until it is set, and
 * at that time records whether the AP has IPA power enabled.
 *
 * Finally, if the AP kernel panics, we update the SMP2P state bits even if
 * we never receive an interrupt from the modem requesting this.
 */

/**
 * struct ipa_smp2p - IPA SMP2P information
 * @ipa:                IPA pointer
 * @valid_state:        SMEM state indicating enabled state is valid
 * @enabled_state:      SMEM state to indicate power is enabled
 * @valid_bit:          Valid bit in 32-bit SMEM state mask
 * @enabled_bit:        Enabled bit in 32-bit SMEM state mask
 * @enabled_bit:        Enabled bit in 32-bit SMEM state mask
 * @clock_query_irq:    IPA interrupt triggered by modem for power query
 * @setup_ready_irq:    IPA interrupt triggered by modem to signal GSI ready
 * @power_on:           Whether IPA power is on
 * @notified:           Whether modem has been notified of power state
 * @disabled:           Whether setup ready interrupt handling is disabled
 * @mutex:              Mutex protecting ready-interrupt/shutdown interlock
 * @panic_notifier:     Panic notifier structure
*/
struct ipa_smp2p {
        struct ipa *ipa;
        struct qcom_smem_state *valid_state;
        struct qcom_smem_state *enabled_state;
        u32 valid_bit;
        u32 enabled_bit;
        u32 clock_query_irq;
        u32 setup_ready_irq;
        bool power_on;
        bool notified;
        bool disabled;
        struct mutex mutex;
        struct notifier_block panic_notifier;
};

/**
 * ipa_smp2p_notify() - use SMP2P to tell modem about IPA power state
 * @smp2p:      SMP2P information
 *
 * This is called either when the modem has requested it (by triggering
 * the modem power query IPA interrupt) or whenever the AP is shutting down
 * (via a panic notifier).  It sets the two SMP2P state bits--one saying
 * whether the IPA power is on, and the other indicating the first bit
 * is valid.
 */
static void ipa_smp2p_notify(struct ipa_smp2p *smp2p)
{
        struct device *dev;
        u32 value;
        u32 mask;

        if (smp2p->notified)
                return;

        dev = &smp2p->ipa->pdev->dev;
        smp2p->power_on = pm_runtime_get_if_active(dev, true) > 0;

        /* Signal whether the IPA power is enabled */
        mask = BIT(smp2p->enabled_bit);
        value = smp2p->power_on ? mask : 0;
        qcom_smem_state_update_bits(smp2p->enabled_state, mask, value);

        /* Now indicate that the enabled flag is valid */
        mask = BIT(smp2p->valid_bit);
        value = mask;
        qcom_smem_state_update_bits(smp2p->valid_state, mask, value);

        smp2p->notified = true;
}

/* Threaded IRQ handler for modem "ipa-clock-query" SMP2P interrupt */
static irqreturn_t ipa_smp2p_modem_clk_query_isr(int irq, void *dev_id)
{
        struct ipa_smp2p *smp2p = dev_id;

        ipa_smp2p_notify(smp2p);

        return IRQ_HANDLED;
}

static int ipa_smp2p_panic_notifier(struct notifier_block *nb,
                                    unsigned long action, void *data)
{
        struct ipa_smp2p *smp2p;

        smp2p = container_of(nb, struct ipa_smp2p, panic_notifier);

        ipa_smp2p_notify(smp2p);

        if (smp2p->power_on)
                ipa_uc_panic_notifier(smp2p->ipa);

        return NOTIFY_DONE;
}

static int ipa_smp2p_panic_notifier_register(struct ipa_smp2p *smp2p)
{
        /* IPA panic handler needs to run before modem shuts down */
        smp2p->panic_notifier.notifier_call = ipa_smp2p_panic_notifier;
        smp2p->panic_notifier.priority = INT_MAX;       /* Do it early */

        return atomic_notifier_chain_register(&panic_notifier_list,
                                              &smp2p->panic_notifier);
}

static void ipa_smp2p_panic_notifier_unregister(struct ipa_smp2p *smp2p)
{
        atomic_notifier_chain_unregister(&panic_notifier_list,
                                         &smp2p->panic_notifier);
}

/* Threaded IRQ handler for modem "ipa-setup-ready" SMP2P interrupt */
static irqreturn_t ipa_smp2p_modem_setup_ready_isr(int irq, void *dev_id)
{
        struct ipa_smp2p *smp2p = dev_id;
        struct device *dev;
        int ret;

        mutex_lock(&smp2p->mutex);

        if (smp2p->disabled)
                goto out_mutex_unlock;
        smp2p->disabled = true;         /* If any others arrive, ignore them */

        /* Power needs to be active for setup */
        dev = &smp2p->ipa->pdev->dev;
        ret = pm_runtime_get_sync(dev);
        if (ret < 0) {
                dev_err(dev, "error %d getting power for setup\n", ret);
                goto out_power_put;
        }

        /* An error here won't cause driver shutdown, so warn if one occurs */
        ret = ipa_setup(smp2p->ipa);
        WARN(ret != 0, "error %d from ipa_setup()\n", ret);

out_power_put:
        pm_runtime_mark_last_busy(dev);
        (void)pm_runtime_put_autosuspend(dev);
out_mutex_unlock:
        mutex_unlock(&smp2p->mutex);

        return IRQ_HANDLED;
}

/* Initialize SMP2P interrupts */
static int ipa_smp2p_irq_init(struct ipa_smp2p *smp2p, const char *name,
                              irq_handler_t handler)
{
        struct device *dev = &smp2p->ipa->pdev->dev;
        unsigned int irq;
        int ret;

        ret = platform_get_irq_byname(smp2p->ipa->pdev, name);
        if (ret <= 0)
                return ret ? : -EINVAL;
        irq = ret;

        ret = request_threaded_irq(irq, NULL, handler, 0, name, smp2p);
        if (ret) {
                dev_err(dev, "error %d requesting \"%s\" IRQ\n", ret, name);
                return ret;
        }

        return irq;
}

static void ipa_smp2p_irq_exit(struct ipa_smp2p *smp2p, u32 irq)
{
        free_irq(irq, smp2p);
}

/* Drop the power reference if it was taken in ipa_smp2p_notify() */
static void ipa_smp2p_power_release(struct ipa *ipa)
{
        struct device *dev = &ipa->pdev->dev;

        if (!ipa->smp2p->power_on)
                return;

        pm_runtime_mark_last_busy(dev);
        (void)pm_runtime_put_autosuspend(dev);
        ipa->smp2p->power_on = false;
}

/* Initialize the IPA SMP2P subsystem */
int ipa_smp2p_init(struct ipa *ipa, bool modem_init)
{
        struct qcom_smem_state *enabled_state;
        struct device *dev = &ipa->pdev->dev;
        struct qcom_smem_state *valid_state;
        struct ipa_smp2p *smp2p;
        u32 enabled_bit;
        u32 valid_bit;
        int ret;

        valid_state = qcom_smem_state_get(dev, "ipa-clock-enabled-valid",
                                          &valid_bit);
        if (IS_ERR(valid_state))
                return PTR_ERR(valid_state);
        if (valid_bit >= 32)            /* BITS_PER_U32 */
                return -EINVAL;

        enabled_state = qcom_smem_state_get(dev, "ipa-clock-enabled",
                                            &enabled_bit);
        if (IS_ERR(enabled_state))
                return PTR_ERR(enabled_state);
        if (enabled_bit >= 32)          /* BITS_PER_U32 */
                return -EINVAL;

        smp2p = kzalloc(sizeof(*smp2p), GFP_KERNEL);
        if (!smp2p)
                return -ENOMEM;

        smp2p->ipa = ipa;

        /* These fields are needed by the power query interrupt
         * handler, so initialize them now.
         */
        mutex_init(&smp2p->mutex);
        smp2p->valid_state = valid_state;
        smp2p->valid_bit = valid_bit;
        smp2p->enabled_state = enabled_state;
        smp2p->enabled_bit = enabled_bit;

        /* We have enough information saved to handle notifications */
        ipa->smp2p = smp2p;

        ret = ipa_smp2p_irq_init(smp2p, "ipa-clock-query",
                                 ipa_smp2p_modem_clk_query_isr);
        if (ret < 0)
                goto err_null_smp2p;
        smp2p->clock_query_irq = ret;

        ret = ipa_smp2p_panic_notifier_register(smp2p);
        if (ret)
                goto err_irq_exit;

        if (modem_init) {
                /* Result will be non-zero (negative for error) */
                ret = ipa_smp2p_irq_init(smp2p, "ipa-setup-ready",
                                         ipa_smp2p_modem_setup_ready_isr);
                if (ret < 0)
                        goto err_notifier_unregister;
                smp2p->setup_ready_irq = ret;
        }

        return 0;

err_notifier_unregister:
        ipa_smp2p_panic_notifier_unregister(smp2p);
err_irq_exit:
        ipa_smp2p_irq_exit(smp2p, smp2p->clock_query_irq);
err_null_smp2p:
        ipa->smp2p = NULL;
        mutex_destroy(&smp2p->mutex);
        kfree(smp2p);

        return ret;
}

void ipa_smp2p_exit(struct ipa *ipa)
{
        struct ipa_smp2p *smp2p = ipa->smp2p;

        if (smp2p->setup_ready_irq)
                ipa_smp2p_irq_exit(smp2p, smp2p->setup_ready_irq);
        ipa_smp2p_panic_notifier_unregister(smp2p);
        ipa_smp2p_irq_exit(smp2p, smp2p->clock_query_irq);
        /* We won't get notified any more; drop power reference (if any) */
        ipa_smp2p_power_release(ipa);
        ipa->smp2p = NULL;
        mutex_destroy(&smp2p->mutex);
        kfree(smp2p);
}

void ipa_smp2p_disable(struct ipa *ipa)
{
        struct ipa_smp2p *smp2p = ipa->smp2p;

        if (!smp2p->setup_ready_irq)
                return;

        mutex_lock(&smp2p->mutex);

        smp2p->disabled = true;

        mutex_unlock(&smp2p->mutex);
}

/* Reset state tracking whether we have notified the modem */
void ipa_smp2p_notify_reset(struct ipa *ipa)
{
        struct ipa_smp2p *smp2p = ipa->smp2p;
        u32 mask;

        if (!smp2p->notified)
                return;

        ipa_smp2p_power_release(ipa);

        /* Reset the power enabled valid flag */
        mask = BIT(smp2p->valid_bit);
        qcom_smem_state_update_bits(smp2p->valid_state, mask, 0);

        /* Mark the power disabled for good measure... */
        mask = BIT(smp2p->enabled_bit);
        qcom_smem_state_update_bits(smp2p->enabled_state, mask, 0);

        smp2p->notified = false;
}