// SPDX-License-Identifier: GPL-2.0
/*
 * Intel Platform Monitoring Technology Crashlog driver
 *
 * Copyright (c) 2020, Intel Corporation.
 * All Rights Reserved.
 *
 * Author: "Alexander Duyck" <alexander.h.duyck@linux.intel.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/overflow.h>

#include "class.h"

#define DRV_NAME                "pmt_crashlog"

/* Crashlog discovery header types */
#define CRASH_TYPE_OOBMSM       1

/* Control Flags */
#define CRASHLOG_FLAG_DISABLE           BIT(28)

/*
 * Bits 29 and 30 control the state of bit 31.
 *
 * Bit 29 will clear bit 31, if set, allowing a new crashlog to be captured.
 * Bit 30 will immediately trigger a crashlog to be generated, setting bit 31.
 * Bit 31 is the read-only status with a 1 indicating log is complete.
 */
#define CRASHLOG_FLAG_TRIGGER_CLEAR     BIT(29)
#define CRASHLOG_FLAG_TRIGGER_EXECUTE   BIT(30)
#define CRASHLOG_FLAG_TRIGGER_COMPLETE  BIT(31)
#define CRASHLOG_FLAG_TRIGGER_MASK      GENMASK(31, 28)

/* Crashlog Discovery Header */
#define CONTROL_OFFSET          0x0
#define GUID_OFFSET             0x4
#define BASE_OFFSET             0x8
#define SIZE_OFFSET             0xC
#define GET_ACCESS(v)           ((v) & GENMASK(3, 0))
#define GET_TYPE(v)             (((v) & GENMASK(7, 4)) >> 4)
#define GET_VERSION(v)          (((v) & GENMASK(19, 16)) >> 16)
/* size is in bytes */
#define GET_SIZE(v)             ((v) * sizeof(u32))

struct crashlog_entry {
        /* entry must be first member of struct */
        struct intel_pmt_entry          entry;
        struct mutex                    control_mutex;
};

struct pmt_crashlog_priv {
        int                     num_entries;
        struct crashlog_entry   entry[];
};

/*
 * I/O
 */
static bool pmt_crashlog_complete(struct intel_pmt_entry *entry)
{
        u32 control = readl(entry->disc_table + CONTROL_OFFSET);

        /* return current value of the crashlog complete flag */
        return !!(control & CRASHLOG_FLAG_TRIGGER_COMPLETE);
}

static bool pmt_crashlog_disabled(struct intel_pmt_entry *entry)
{
        u32 control = readl(entry->disc_table + CONTROL_OFFSET);

        /* return current value of the crashlog disabled flag */
        return !!(control & CRASHLOG_FLAG_DISABLE);
}

static bool pmt_crashlog_supported(struct intel_pmt_entry *entry)
{
        u32 discovery_header = readl(entry->disc_table + CONTROL_OFFSET);
        u32 crash_type, version;

        crash_type = GET_TYPE(discovery_header);
        version = GET_VERSION(discovery_header);

        /*
         * Currently we only recognize OOBMSM version 0 devices.
         * We can ignore all other crashlog devices in the system.
         */
        return crash_type == CRASH_TYPE_OOBMSM && version == 0;
}

static void pmt_crashlog_set_disable(struct intel_pmt_entry *entry,
                                     bool disable)
{
        u32 control = readl(entry->disc_table + CONTROL_OFFSET);

        /* clear trigger bits so we are only modifying disable flag */
        control &= ~CRASHLOG_FLAG_TRIGGER_MASK;

        if (disable)
                control |= CRASHLOG_FLAG_DISABLE;
        else
                control &= ~CRASHLOG_FLAG_DISABLE;

        writel(control, entry->disc_table + CONTROL_OFFSET);
}

static void pmt_crashlog_set_clear(struct intel_pmt_entry *entry)
{
        u32 control = readl(entry->disc_table + CONTROL_OFFSET);

        control &= ~CRASHLOG_FLAG_TRIGGER_MASK;
        control |= CRASHLOG_FLAG_TRIGGER_CLEAR;

        writel(control, entry->disc_table + CONTROL_OFFSET);
}

static void pmt_crashlog_set_execute(struct intel_pmt_entry *entry)
{
        u32 control = readl(entry->disc_table + CONTROL_OFFSET);

        control &= ~CRASHLOG_FLAG_TRIGGER_MASK;
        control |= CRASHLOG_FLAG_TRIGGER_EXECUTE;

        writel(control, entry->disc_table + CONTROL_OFFSET);
}

/*
 * sysfs
 */
static ssize_t
enable_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct intel_pmt_entry *entry = dev_get_drvdata(dev);
        int enabled = !pmt_crashlog_disabled(entry);

        return sprintf(buf, "%d\n", enabled);
}

static ssize_t
enable_store(struct device *dev, struct device_attribute *attr,
            const char *buf, size_t count)
{
        struct crashlog_entry *entry;
        bool enabled;
        int result;

        entry = dev_get_drvdata(dev);

        result = kstrtobool(buf, &enabled);
        if (result)
                return result;

        mutex_lock(&entry->control_mutex);
        pmt_crashlog_set_disable(&entry->entry, !enabled);
        mutex_unlock(&entry->control_mutex);

        return count;
}
static DEVICE_ATTR_RW(enable);

static ssize_t
trigger_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct intel_pmt_entry *entry;
        int trigger;

        entry = dev_get_drvdata(dev);
        trigger = pmt_crashlog_complete(entry);

        return sprintf(buf, "%d\n", trigger);
}

static ssize_t
trigger_store(struct device *dev, struct device_attribute *attr,
            const char *buf, size_t count)
{
        struct crashlog_entry *entry;
        bool trigger;
        int result;

        entry = dev_get_drvdata(dev);

        result = kstrtobool(buf, &trigger);
        if (result)
                return result;

        mutex_lock(&entry->control_mutex);

        if (!trigger) {
                pmt_crashlog_set_clear(&entry->entry);
        } else if (pmt_crashlog_complete(&entry->entry)) {
                /* we cannot trigger a new crash if one is still pending */
                result = -EEXIST;
                goto err;
        } else if (pmt_crashlog_disabled(&entry->entry)) {
                /* if device is currently disabled, return busy */
                result = -EBUSY;
                goto err;
        } else {
                pmt_crashlog_set_execute(&entry->entry);
        }

        result = count;
err:
        mutex_unlock(&entry->control_mutex);
        return result;
}
static DEVICE_ATTR_RW(trigger);

static struct attribute *pmt_crashlog_attrs[] = {
        &dev_attr_enable.attr,
        &dev_attr_trigger.attr,
        NULL
};

static const struct attribute_group pmt_crashlog_group = {
        .attrs  = pmt_crashlog_attrs,
};

static int pmt_crashlog_header_decode(struct intel_pmt_entry *entry,
                                      struct intel_pmt_header *header,
                                      struct device *dev)
{
        void __iomem *disc_table = entry->disc_table;
        struct crashlog_entry *crashlog;

        if (!pmt_crashlog_supported(entry))
                return 1;

        /* initialize control mutex */
        crashlog = container_of(entry, struct crashlog_entry, entry);
        mutex_init(&crashlog->control_mutex);

        header->access_type = GET_ACCESS(readl(disc_table));
        header->guid = readl(disc_table + GUID_OFFSET);
        header->base_offset = readl(disc_table + BASE_OFFSET);

        /* Size is measured in DWORDS, but accessor returns bytes */
        header->size = GET_SIZE(readl(disc_table + SIZE_OFFSET));

        return 0;
}

static DEFINE_XARRAY_ALLOC(crashlog_array);
static struct intel_pmt_namespace pmt_crashlog_ns = {
        .name = "crashlog",
        .xa = &crashlog_array,
        .attr_grp = &pmt_crashlog_group,
        .pmt_header_decode = pmt_crashlog_header_decode,
};

/*
 * initialization
 */
static int pmt_crashlog_remove(struct platform_device *pdev)
{
        struct pmt_crashlog_priv *priv = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < priv->num_entries; i++)
                intel_pmt_dev_destroy(&priv->entry[i].entry, &pmt_crashlog_ns);

        return 0;
}

static int pmt_crashlog_probe(struct platform_device *pdev)
{
        struct pmt_crashlog_priv *priv;
        size_t size;
        int i, ret;

        size = struct_size(priv, entry, pdev->num_resources);
        priv = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        platform_set_drvdata(pdev, priv);

        for (i = 0; i < pdev->num_resources; i++) {
                struct intel_pmt_entry *entry = &priv->entry[i].entry;

                ret = intel_pmt_dev_create(entry, &pmt_crashlog_ns, pdev, i);
                if (ret < 0)
                        goto abort_probe;
                if (ret)
                        continue;

                priv->num_entries++;
        }

        return 0;
abort_probe:
        pmt_crashlog_remove(pdev);
        return ret;
}

static struct platform_driver pmt_crashlog_driver = {
        .driver = {
                .name   = DRV_NAME,
        },
        .remove = pmt_crashlog_remove,
        .probe  = pmt_crashlog_probe,
};

static int __init pmt_crashlog_init(void)
{
        return platform_driver_register(&pmt_crashlog_driver);
}

static void __exit pmt_crashlog_exit(void)
{
        platform_driver_unregister(&pmt_crashlog_driver);
        xa_destroy(&crashlog_array);
}

module_init(pmt_crashlog_init);
module_exit(pmt_crashlog_exit);

MODULE_AUTHOR("Alexander Duyck <alexander.h.duyck@linux.intel.com>");
MODULE_DESCRIPTION("Intel PMT Crashlog driver");
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_LICENSE("GPL v2");