// SPDX-License-Identifier: GPL-2.0+
/*
 * Mellanox hotplug driver
 *
 * Copyright (C) 2016-2020 Mellanox Technologies
 */

#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_data/mlxreg.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/string_helpers.h>
#include <linux/regmap.h>
#include <linux/workqueue.h>

/* Offset of event and mask registers from status register. */
#define MLXREG_HOTPLUG_EVENT_OFF        1
#define MLXREG_HOTPLUG_MASK_OFF         2
#define MLXREG_HOTPLUG_AGGR_MASK_OFF    1

/* ASIC good health mask. */
#define MLXREG_HOTPLUG_GOOD_HEALTH_MASK 0x02

#define MLXREG_HOTPLUG_ATTRS_MAX        24
#define MLXREG_HOTPLUG_NOT_ASSERT       3

/**
 * struct mlxreg_hotplug_priv_data - platform private data:
 * @irq: platform device interrupt number;
 * @dev: basic device;
 * @pdev: platform device;
 * @plat: platform data;
 * @regmap: register map handle;
 * @dwork_irq: delayed work template;
 * @lock: spin lock;
 * @hwmon: hwmon device;
 * @mlxreg_hotplug_attr: sysfs attributes array;
 * @mlxreg_hotplug_dev_attr: sysfs sensor device attribute array;
 * @group: sysfs attribute group;
 * @groups: list of sysfs attribute group for hwmon registration;
 * @cell: location of top aggregation interrupt register;
 * @mask: top aggregation interrupt common mask;
 * @aggr_cache: last value of aggregation register status;
 * @after_probe: flag indication probing completion;
 * @not_asserted: number of entries in workqueue with no signal assertion;
 */
struct mlxreg_hotplug_priv_data {
        int irq;
        struct device *dev;
        struct platform_device *pdev;
        struct mlxreg_hotplug_platform_data *plat;
        struct regmap *regmap;
        struct delayed_work dwork_irq;
        spinlock_t lock; /* sync with interrupt */
        struct device *hwmon;
        struct attribute *mlxreg_hotplug_attr[MLXREG_HOTPLUG_ATTRS_MAX + 1];
        struct sensor_device_attribute_2
                        mlxreg_hotplug_dev_attr[MLXREG_HOTPLUG_ATTRS_MAX];
        struct attribute_group group;
        const struct attribute_group *groups[2];
        u32 cell;
        u32 mask;
        u32 aggr_cache;
        bool after_probe;
        u8 not_asserted;
};

/* Environment variables array for udev. */
static char *mlxreg_hotplug_udev_envp[] = { NULL, NULL };

static int
mlxreg_hotplug_udev_event_send(struct kobject *kobj,
                               struct mlxreg_core_data *data, bool action)
{
        char event_str[MLXREG_CORE_LABEL_MAX_SIZE + 2];
        char label[MLXREG_CORE_LABEL_MAX_SIZE] = { 0 };

        mlxreg_hotplug_udev_envp[0] = event_str;
        string_upper(label, data->label);
        snprintf(event_str, MLXREG_CORE_LABEL_MAX_SIZE, "%s=%d", label, !!action);

        return kobject_uevent_env(kobj, KOBJ_CHANGE, mlxreg_hotplug_udev_envp);
}

static int mlxreg_hotplug_device_create(struct mlxreg_hotplug_priv_data *priv,
                                        struct mlxreg_core_data *data)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct i2c_client *client;

        /* Notify user by sending hwmon uevent. */
        mlxreg_hotplug_udev_event_send(&priv->hwmon->kobj, data, true);

        /*
         * Return if adapter number is negative. It could be in case hotplug
         * event is not associated with hotplug device.
         */
        if (data->hpdev.nr < 0)
                return 0;

        pdata = dev_get_platdata(&priv->pdev->dev);
        data->hpdev.adapter = i2c_get_adapter(data->hpdev.nr +
                                              pdata->shift_nr);
        if (!data->hpdev.adapter) {
                dev_err(priv->dev, "Failed to get adapter for bus %d\n",
                        data->hpdev.nr + pdata->shift_nr);
                return -EFAULT;
        }

        client = i2c_new_client_device(data->hpdev.adapter,
                                       data->hpdev.brdinfo);
        if (IS_ERR(client)) {
                dev_err(priv->dev, "Failed to create client %s at bus %d at addr 0x%02x\n",
                        data->hpdev.brdinfo->type, data->hpdev.nr +
                        pdata->shift_nr, data->hpdev.brdinfo->addr);

                i2c_put_adapter(data->hpdev.adapter);
                data->hpdev.adapter = NULL;
                return PTR_ERR(client);
        }

        data->hpdev.client = client;

        return 0;
}

static void
mlxreg_hotplug_device_destroy(struct mlxreg_hotplug_priv_data *priv,
                              struct mlxreg_core_data *data)
{
        /* Notify user by sending hwmon uevent. */
        mlxreg_hotplug_udev_event_send(&priv->hwmon->kobj, data, false);

        if (data->hpdev.client) {
                i2c_unregister_device(data->hpdev.client);
                data->hpdev.client = NULL;
        }

        if (data->hpdev.adapter) {
                i2c_put_adapter(data->hpdev.adapter);
                data->hpdev.adapter = NULL;
        }
}

static ssize_t mlxreg_hotplug_attr_show(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct mlxreg_hotplug_priv_data *priv = dev_get_drvdata(dev);
        struct mlxreg_core_hotplug_platform_data *pdata;
        int index = to_sensor_dev_attr_2(attr)->index;
        int nr = to_sensor_dev_attr_2(attr)->nr;
        struct mlxreg_core_item *item;
        struct mlxreg_core_data *data;
        u32 regval;
        int ret;

        pdata = dev_get_platdata(&priv->pdev->dev);
        item = pdata->items + nr;
        data = item->data + index;

        ret = regmap_read(priv->regmap, data->reg, &regval);
        if (ret)
                return ret;

        if (item->health) {
                regval &= data->mask;
        } else {
                /* Bit = 0 : functional if item->inversed is true. */
                if (item->inversed)
                        regval = !(regval & data->mask);
                else
                        regval = !!(regval & data->mask);
        }

        return sprintf(buf, "%u\n", regval);
}

#define PRIV_ATTR(i) priv->mlxreg_hotplug_attr[i]
#define PRIV_DEV_ATTR(i) priv->mlxreg_hotplug_dev_attr[i]

static int mlxreg_hotplug_attr_init(struct mlxreg_hotplug_priv_data *priv)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct mlxreg_core_item *item;
        struct mlxreg_core_data *data;
        unsigned long mask;
        u32 regval;
        int num_attrs = 0, id = 0, i, j, k, ret;

        pdata = dev_get_platdata(&priv->pdev->dev);
        item = pdata->items;

        /* Go over all kinds of items - psu, pwr, fan. */
        for (i = 0; i < pdata->counter; i++, item++) {
                if (item->capability) {
                        /*
                         * Read group capability register to get actual number
                         * of interrupt capable components and set group mask
                         * accordingly.
                         */
                        ret = regmap_read(priv->regmap, item->capability,
                                          &regval);
                        if (ret)
                                return ret;

                        item->mask = GENMASK((regval & item->mask) - 1, 0);
                }

                data = item->data;

                /* Go over all unmasked units within item. */
                mask = item->mask;
                k = 0;
                for_each_set_bit(j, &mask, item->count) {
                        if (data->capability) {
                                /*
                                 * Read capability register and skip non
                                 * relevant attributes.
                                 */
                                ret = regmap_read(priv->regmap,
                                                  data->capability, &regval);
                                if (ret)
                                        return ret;
                                if (!(regval & data->bit)) {
                                        data++;
                                        continue;
                                }
                        }
                        PRIV_ATTR(id) = &PRIV_DEV_ATTR(id).dev_attr.attr;
                        PRIV_ATTR(id)->name = devm_kasprintf(&priv->pdev->dev,
                                                             GFP_KERNEL,
                                                             data->label);

                        if (!PRIV_ATTR(id)->name) {
                                dev_err(priv->dev, "Memory allocation failed for attr %d.\n",
                                        id);
                                return -ENOMEM;
                        }

                        PRIV_DEV_ATTR(id).dev_attr.attr.name =
                                                        PRIV_ATTR(id)->name;
                        PRIV_DEV_ATTR(id).dev_attr.attr.mode = 0444;
                        PRIV_DEV_ATTR(id).dev_attr.show =
                                                mlxreg_hotplug_attr_show;
                        PRIV_DEV_ATTR(id).nr = i;
                        PRIV_DEV_ATTR(id).index = k;
                        sysfs_attr_init(&PRIV_DEV_ATTR(id).dev_attr.attr);
                        data++;
                        id++;
                        k++;
                }
                num_attrs += k;
        }

        priv->group.attrs = devm_kcalloc(&priv->pdev->dev,
                                         num_attrs,
                                         sizeof(struct attribute *),
                                         GFP_KERNEL);
        if (!priv->group.attrs)
                return -ENOMEM;

        priv->group.attrs = priv->mlxreg_hotplug_attr;
        priv->groups[0] = &priv->group;
        priv->groups[1] = NULL;

        return 0;
}

static void
mlxreg_hotplug_work_helper(struct mlxreg_hotplug_priv_data *priv,
                           struct mlxreg_core_item *item)
{
        struct mlxreg_core_data *data;
        unsigned long asserted;
        u32 regval, bit;
        int ret;

        /*
         * Validate if item related to received signal type is valid.
         * It should never happen, excepted the situation when some
         * piece of hardware is broken. In such situation just produce
         * error message and return. Caller must continue to handle the
         * signals from other devices if any.
         */
        if (unlikely(!item)) {
                dev_err(priv->dev, "False signal: at offset:mask 0x%02x:0x%02x.\n",
                        item->reg, item->mask);

                return;
        }

        /* Mask event. */
        ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_MASK_OFF,
                           0);
        if (ret)
                goto out;

        /* Read status. */
        ret = regmap_read(priv->regmap, item->reg, &regval);
        if (ret)
                goto out;

        /* Set asserted bits and save last status. */
        regval &= item->mask;
        asserted = item->cache ^ regval;
        item->cache = regval;

        for_each_set_bit(bit, &asserted, 8) {
                data = item->data + bit;
                if (regval & BIT(bit)) {
                        if (item->inversed)
                                mlxreg_hotplug_device_destroy(priv, data);
                        else
                                mlxreg_hotplug_device_create(priv, data);
                } else {
                        if (item->inversed)
                                mlxreg_hotplug_device_create(priv, data);
                        else
                                mlxreg_hotplug_device_destroy(priv, data);
                }
        }

        /* Acknowledge event. */
        ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_EVENT_OFF,
                           0);
        if (ret)
                goto out;

        /* Unmask event. */
        ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_MASK_OFF,
                           item->mask);

 out:
        if (ret)
                dev_err(priv->dev, "Failed to complete workqueue.\n");
}

static void
mlxreg_hotplug_health_work_helper(struct mlxreg_hotplug_priv_data *priv,
                                  struct mlxreg_core_item *item)
{
        struct mlxreg_core_data *data = item->data;
        u32 regval;
        int i, ret = 0;

        for (i = 0; i < item->count; i++, data++) {
                /* Mask event. */
                ret = regmap_write(priv->regmap, data->reg +
                                   MLXREG_HOTPLUG_MASK_OFF, 0);
                if (ret)
                        goto out;

                /* Read status. */
                ret = regmap_read(priv->regmap, data->reg, &regval);
                if (ret)
                        goto out;

                regval &= data->mask;

                if (item->cache == regval)
                        goto ack_event;

                /*
                 * ASIC health indication is provided through two bits. Bits
                 * value 0x2 indicates that ASIC reached the good health, value
                 * 0x0 indicates ASIC the bad health or dormant state and value
                 * 0x3 indicates the booting state. During ASIC reset it should
                 * pass the following states: dormant -> booting -> good.
                 */
                if (regval == MLXREG_HOTPLUG_GOOD_HEALTH_MASK) {
                        if (!data->attached) {
                                /*
                                 * ASIC is in steady state. Connect associated
                                 * device, if configured.
                                 */
                                mlxreg_hotplug_device_create(priv, data);
                                data->attached = true;
                        }
                } else {
                        if (data->attached) {
                                /*
                                 * ASIC health is failed after ASIC has been
                                 * in steady state. Disconnect associated
                                 * device, if it has been connected.
                                 */
                                mlxreg_hotplug_device_destroy(priv, data);
                                data->attached = false;
                                data->health_cntr = 0;
                        }
                }
                item->cache = regval;
ack_event:
                /* Acknowledge event. */
                ret = regmap_write(priv->regmap, data->reg +
                                   MLXREG_HOTPLUG_EVENT_OFF, 0);
                if (ret)
                        goto out;

                /* Unmask event. */
                ret = regmap_write(priv->regmap, data->reg +
                                   MLXREG_HOTPLUG_MASK_OFF, data->mask);
                if (ret)
                        goto out;
        }

 out:
        if (ret)
                dev_err(priv->dev, "Failed to complete workqueue.\n");
}

/*
 * mlxreg_hotplug_work_handler - performs traversing of device interrupt
 * registers according to the below hierarchy schema:
 *
 *                              Aggregation registers (status/mask)
 * PSU registers:               *---*
 * *-----------------*          |   |
 * |status/event/mask|----->    | * |
 * *-----------------*          |   |
 * Power registers:             |   |
 * *-----------------*          |   |
 * |status/event/mask|----->    | * |
 * *-----------------*          |   |
 * FAN registers:               |   |--> CPU
 * *-----------------*          |   |
 * |status/event/mask|----->    | * |
 * *-----------------*          |   |
 * ASIC registers:              |   |
 * *-----------------*          |   |
 * |status/event/mask|----->    | * |
 * *-----------------*          |   |
 *                              *---*
 *
 * In case some system changed are detected: FAN in/out, PSU in/out, power
 * cable attached/detached, ASIC health good/bad, relevant device is created
 * or destroyed.
 */
static void mlxreg_hotplug_work_handler(struct work_struct *work)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct mlxreg_hotplug_priv_data *priv;
        struct mlxreg_core_item *item;
        u32 regval, aggr_asserted;
        unsigned long flags;
        int i, ret;

        priv = container_of(work, struct mlxreg_hotplug_priv_data,
                            dwork_irq.work);
        pdata = dev_get_platdata(&priv->pdev->dev);
        item = pdata->items;

        /* Mask aggregation event. */
        ret = regmap_write(priv->regmap, pdata->cell +
                           MLXREG_HOTPLUG_AGGR_MASK_OFF, 0);
        if (ret < 0)
                goto out;

        /* Read aggregation status. */
        ret = regmap_read(priv->regmap, pdata->cell, &regval);
        if (ret)
                goto out;

        regval &= pdata->mask;
        aggr_asserted = priv->aggr_cache ^ regval;
        priv->aggr_cache = regval;

        /*
         * Handler is invoked, but no assertion is detected at top aggregation
         * status level. Set aggr_asserted to mask value to allow handler extra
         * run over all relevant signals to recover any missed signal.
         */
        if (priv->not_asserted == MLXREG_HOTPLUG_NOT_ASSERT) {
                priv->not_asserted = 0;
                aggr_asserted = pdata->mask;
        }
        if (!aggr_asserted)
                goto unmask_event;

        /* Handle topology and health configuration changes. */
        for (i = 0; i < pdata->counter; i++, item++) {
                if (aggr_asserted & item->aggr_mask) {
                        if (item->health)
                                mlxreg_hotplug_health_work_helper(priv, item);
                        else
                                mlxreg_hotplug_work_helper(priv, item);
                }
        }

        spin_lock_irqsave(&priv->lock, flags);

        /*
         * It is possible, that some signals have been inserted, while
         * interrupt has been masked by mlxreg_hotplug_work_handler. In this
         * case such signals will be missed. In order to handle these signals
         * delayed work is canceled and work task re-scheduled for immediate
         * execution. It allows to handle missed signals, if any. In other case
         * work handler just validates that no new signals have been received
         * during masking.
         */
        cancel_delayed_work(&priv->dwork_irq);
        schedule_delayed_work(&priv->dwork_irq, 0);

        spin_unlock_irqrestore(&priv->lock, flags);

        return;

unmask_event:
        priv->not_asserted++;
        /* Unmask aggregation event (no need acknowledge). */
        ret = regmap_write(priv->regmap, pdata->cell +
                           MLXREG_HOTPLUG_AGGR_MASK_OFF, pdata->mask);

 out:
        if (ret)
                dev_err(priv->dev, "Failed to complete workqueue.\n");
}

static int mlxreg_hotplug_set_irq(struct mlxreg_hotplug_priv_data *priv)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct mlxreg_core_item *item;
        struct mlxreg_core_data *data;
        u32 regval;
        int i, j, ret;

        pdata = dev_get_platdata(&priv->pdev->dev);
        item = pdata->items;

        for (i = 0; i < pdata->counter; i++, item++) {
                /* Clear group presense event. */
                ret = regmap_write(priv->regmap, item->reg +
                                   MLXREG_HOTPLUG_EVENT_OFF, 0);
                if (ret)
                        goto out;

                /*
                 * Verify if hardware configuration requires to disable
                 * interrupt capability for some of components.
                 */
                data = item->data;
                for (j = 0; j < item->count; j++, data++) {
                        /* Verify if the attribute has capability register. */
                        if (data->capability) {
                                /* Read capability register. */
                                ret = regmap_read(priv->regmap,
                                                  data->capability, &regval);
                                if (ret)
                                        goto out;

                                if (!(regval & data->bit))
                                        item->mask &= ~BIT(j);
                        }
                }

                /* Set group initial status as mask and unmask group event. */
                if (item->inversed) {
                        item->cache = item->mask;
                        ret = regmap_write(priv->regmap, item->reg +
                                           MLXREG_HOTPLUG_MASK_OFF,
                                           item->mask);
                        if (ret)
                                goto out;
                }
        }

        /* Keep aggregation initial status as zero and unmask events. */
        ret = regmap_write(priv->regmap, pdata->cell +
                           MLXREG_HOTPLUG_AGGR_MASK_OFF, pdata->mask);
        if (ret)
                goto out;

        /* Keep low aggregation initial status as zero and unmask events. */
        if (pdata->cell_low) {
                ret = regmap_write(priv->regmap, pdata->cell_low +
                                   MLXREG_HOTPLUG_AGGR_MASK_OFF,
                                   pdata->mask_low);
                if (ret)
                        goto out;
        }

        /* Invoke work handler for initializing hot plug devices setting. */
        mlxreg_hotplug_work_handler(&priv->dwork_irq.work);

 out:
        if (ret)
                dev_err(priv->dev, "Failed to set interrupts.\n");
        enable_irq(priv->irq);
        return ret;
}

static void mlxreg_hotplug_unset_irq(struct mlxreg_hotplug_priv_data *priv)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct mlxreg_core_item *item;
        struct mlxreg_core_data *data;
        int count, i, j;

        pdata = dev_get_platdata(&priv->pdev->dev);
        item = pdata->items;
        disable_irq(priv->irq);
        cancel_delayed_work_sync(&priv->dwork_irq);

        /* Mask low aggregation event, if defined. */
        if (pdata->cell_low)
                regmap_write(priv->regmap, pdata->cell_low +
                             MLXREG_HOTPLUG_AGGR_MASK_OFF, 0);

        /* Mask aggregation event. */
        regmap_write(priv->regmap, pdata->cell + MLXREG_HOTPLUG_AGGR_MASK_OFF,
                     0);

        /* Clear topology configurations. */
        for (i = 0; i < pdata->counter; i++, item++) {
                data = item->data;
                /* Mask group presense event. */
                regmap_write(priv->regmap, data->reg + MLXREG_HOTPLUG_MASK_OFF,
                             0);
                /* Clear group presense event. */
                regmap_write(priv->regmap, data->reg +
                             MLXREG_HOTPLUG_EVENT_OFF, 0);

                /* Remove all the attached devices in group. */
                count = item->count;
                for (j = 0; j < count; j++, data++)
                        mlxreg_hotplug_device_destroy(priv, data);
        }
}

static irqreturn_t mlxreg_hotplug_irq_handler(int irq, void *dev)
{
        struct mlxreg_hotplug_priv_data *priv;

        priv = (struct mlxreg_hotplug_priv_data *)dev;

        /* Schedule work task for immediate execution.*/
        schedule_delayed_work(&priv->dwork_irq, 0);

        return IRQ_HANDLED;
}

static int mlxreg_hotplug_probe(struct platform_device *pdev)
{
        struct mlxreg_core_hotplug_platform_data *pdata;
        struct mlxreg_hotplug_priv_data *priv;
        struct i2c_adapter *deferred_adap;
        int err;

        pdata = dev_get_platdata(&pdev->dev);
        if (!pdata) {
                dev_err(&pdev->dev, "Failed to get platform data.\n");
                return -EINVAL;
        }

        /* Defer probing if the necessary adapter is not configured yet. */
        deferred_adap = i2c_get_adapter(pdata->deferred_nr);
        if (!deferred_adap)
                return -EPROBE_DEFER;
        i2c_put_adapter(deferred_adap);

        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        if (pdata->irq) {
                priv->irq = pdata->irq;
        } else {
                priv->irq = platform_get_irq(pdev, 0);
                if (priv->irq < 0)
                        return priv->irq;
        }

        priv->regmap = pdata->regmap;
        priv->dev = pdev->dev.parent;
        priv->pdev = pdev;

        err = devm_request_irq(&pdev->dev, priv->irq,
                               mlxreg_hotplug_irq_handler, IRQF_TRIGGER_FALLING
                               | IRQF_SHARED, "mlxreg-hotplug", priv);
        if (err) {
                dev_err(&pdev->dev, "Failed to request irq: %d\n", err);
                return err;
        }

        disable_irq(priv->irq);
        spin_lock_init(&priv->lock);
        INIT_DELAYED_WORK(&priv->dwork_irq, mlxreg_hotplug_work_handler);
        dev_set_drvdata(&pdev->dev, priv);

        err = mlxreg_hotplug_attr_init(priv);
        if (err) {
                dev_err(&pdev->dev, "Failed to allocate attributes: %d\n",
                        err);
                return err;
        }

        priv->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev,
                                        "mlxreg_hotplug", priv, priv->groups);
        if (IS_ERR(priv->hwmon)) {
                dev_err(&pdev->dev, "Failed to register hwmon device %ld\n",
                        PTR_ERR(priv->hwmon));
                return PTR_ERR(priv->hwmon);
        }

        /* Perform initial interrupts setup. */
        mlxreg_hotplug_set_irq(priv);
        priv->after_probe = true;

        return 0;
}

static int mlxreg_hotplug_remove(struct platform_device *pdev)
{
        struct mlxreg_hotplug_priv_data *priv = dev_get_drvdata(&pdev->dev);

        /* Clean interrupts setup. */
        mlxreg_hotplug_unset_irq(priv);
        devm_free_irq(&pdev->dev, priv->irq, priv);

        return 0;
}

static struct platform_driver mlxreg_hotplug_driver = {
        .driver = {
                .name = "mlxreg-hotplug",
        },
        .probe = mlxreg_hotplug_probe,
        .remove = mlxreg_hotplug_remove,
};

module_platform_driver(mlxreg_hotplug_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
MODULE_DESCRIPTION("Mellanox regmap hotplug platform driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("platform:mlxreg-hotplug");