// SPDX-License-Identifier: GPL-2.0
/*
 * NVMEM layout bus handling
 *
 * Copyright (C) 2023 Bootlin
 * Author: Miquel Raynal <miquel.raynal@bootlin.com
 */

#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>

#include "internals.h"

#define to_nvmem_layout_driver(drv) \
        (container_of_const((drv), struct nvmem_layout_driver, driver))
#define to_nvmem_layout_device(_dev) \
        container_of((_dev), struct nvmem_layout, dev)

static int nvmem_layout_bus_match(struct device *dev, const struct device_driver *drv)
{
        return of_driver_match_device(dev, drv);
}

static int nvmem_layout_bus_probe(struct device *dev)
{
        struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver);
        struct nvmem_layout *layout = to_nvmem_layout_device(dev);

        if (!drv->probe || !drv->remove)
                return -EINVAL;

        return drv->probe(layout);
}

static void nvmem_layout_bus_remove(struct device *dev)
{
        struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver);
        struct nvmem_layout *layout = to_nvmem_layout_device(dev);

        return drv->remove(layout);
}

static int nvmem_layout_bus_uevent(const struct device *dev,
                                   struct kobj_uevent_env *env)
{
        int ret;

        ret = of_device_uevent_modalias(dev, env);
        if (ret != -ENODEV)
                return ret;

        return 0;
}

static const struct bus_type nvmem_layout_bus_type = {
        .name           = "nvmem-layout",
        .match          = nvmem_layout_bus_match,
        .probe          = nvmem_layout_bus_probe,
        .remove         = nvmem_layout_bus_remove,
        .uevent         = nvmem_layout_bus_uevent,
};

int __nvmem_layout_driver_register(struct nvmem_layout_driver *drv,
                                   struct module *owner)
{
        drv->driver.bus = &nvmem_layout_bus_type;
        drv->driver.owner = owner;

        return driver_register(&drv->driver);
}
EXPORT_SYMBOL_GPL(__nvmem_layout_driver_register);

void nvmem_layout_driver_unregister(struct nvmem_layout_driver *drv)
{
        driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_GPL(nvmem_layout_driver_unregister);

static void nvmem_layout_release_device(struct device *dev)
{
        struct nvmem_layout *layout = to_nvmem_layout_device(dev);

        of_node_put(layout->dev.of_node);
        kfree(layout);
}

static int nvmem_layout_create_device(struct nvmem_device *nvmem,
                                      struct device_node *np)
{
        struct nvmem_layout *layout;
        struct device *dev;
        int ret;

        layout = kzalloc_obj(*layout);
        if (!layout)
                return -ENOMEM;

        /* Create a bidirectional link */
        layout->nvmem = nvmem;
        nvmem->layout = layout;

        /* Device model registration */
        dev = &layout->dev;
        device_initialize(dev);
        dev->parent = &nvmem->dev;
        dev->bus = &nvmem_layout_bus_type;
        dev->release = nvmem_layout_release_device;
        dev->coherent_dma_mask = DMA_BIT_MASK(32);
        dev->dma_mask = &dev->coherent_dma_mask;
        device_set_node(dev, of_fwnode_handle(of_node_get(np)));
        of_device_make_bus_id(dev);
        of_msi_configure(dev, dev->of_node);

        ret = device_add(dev);
        if (ret) {
                put_device(dev);
                return ret;
        }

        return 0;
}

static const struct of_device_id of_nvmem_layout_skip_table[] = {
        { .compatible = "fixed-layout", },
        {}
};

static int nvmem_layout_bus_populate(struct nvmem_device *nvmem,
                                     struct device_node *layout_dn)
{
        int ret;

        /* Make sure it has a compatible property */
        if (!of_property_present(layout_dn, "compatible")) {
                pr_debug("%s() - skipping %pOF, no compatible prop\n",
                         __func__, layout_dn);
                return 0;
        }

        /* Fixed layouts are parsed manually somewhere else for now */
        if (of_match_node(of_nvmem_layout_skip_table, layout_dn)) {
                pr_debug("%s() - skipping %pOF node\n", __func__, layout_dn);
                return 0;
        }

        if (of_node_check_flag(layout_dn, OF_POPULATED_BUS)) {
                pr_debug("%s() - skipping %pOF, already populated\n",
                         __func__, layout_dn);

                return 0;
        }

        /* NVMEM layout buses expect only a single device representing the layout */
        ret = nvmem_layout_create_device(nvmem, layout_dn);
        if (ret)
                return ret;

        of_node_set_flag(layout_dn, OF_POPULATED_BUS);

        return 0;
}

struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
{
        return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
}
EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);

/*
 * Returns the number of devices populated, 0 if the operation was not relevant
 * for this nvmem device, an error code otherwise.
 */
int nvmem_populate_layout(struct nvmem_device *nvmem)
{
        struct device_node *layout_dn;
        int ret;

        layout_dn = of_nvmem_layout_get_container(nvmem);
        if (!layout_dn)
                return 0;

        /* Populate the layout device */
        device_links_supplier_sync_state_pause();
        ret = nvmem_layout_bus_populate(nvmem, layout_dn);
        device_links_supplier_sync_state_resume();

        of_node_put(layout_dn);
        return ret;
}

void nvmem_destroy_layout(struct nvmem_device *nvmem)
{
        struct device *dev;

        if (!nvmem->layout)
                return;

        dev = &nvmem->layout->dev;
        of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
        device_unregister(dev);
}

int nvmem_layout_bus_register(void)
{
        return bus_register(&nvmem_layout_bus_type);
}

void nvmem_layout_bus_unregister(void)
{
        bus_unregister(&nvmem_layout_bus_type);
}