/*
 * MSI framework for platform devices
 *
 * Copyright (C) 2015 ARM Limited, All Rights Reserved.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/device.h>
#include <linux/idr.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/msi.h>
#include <linux/slab.h>

#define DEV_ID_SHIFT    21
#define MAX_DEV_MSIS    (1 << (32 - DEV_ID_SHIFT))

/*
 * Internal data structure containing a (made up, but unique) devid
 * and the callback to write the MSI message.
 */
struct platform_msi_priv_data {
        struct device           *dev;
        void                    *host_data;
        msi_alloc_info_t        arg;
        irq_write_msi_msg_t     write_msg;
        int                     devid;
};

/* The devid allocator */
static DEFINE_IDA(platform_msi_devid_ida);

#ifdef GENERIC_MSI_DOMAIN_OPS
/*
 * Convert an msi_desc to a globaly unique identifier (per-device
 * devid + msi_desc position in the msi_list).
 */
static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
{
        u32 devid;

        devid = desc->platform.msi_priv_data->devid;

        return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
}

static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
{
        arg->desc = desc;
        arg->hwirq = platform_msi_calc_hwirq(desc);
}

static int platform_msi_init(struct irq_domain *domain,
                             struct msi_domain_info *info,
                             unsigned int virq, irq_hw_number_t hwirq,
                             msi_alloc_info_t *arg)
{
        return irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
                                             info->chip, info->chip_data);
}
#else
#define platform_msi_set_desc           NULL
#define platform_msi_init               NULL
#endif

static void platform_msi_update_dom_ops(struct msi_domain_info *info)
{
        struct msi_domain_ops *ops = info->ops;

        BUG_ON(!ops);

        if (ops->msi_init == NULL)
                ops->msi_init = platform_msi_init;
        if (ops->set_desc == NULL)
                ops->set_desc = platform_msi_set_desc;
}

static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
{
        struct msi_desc *desc = irq_data_get_msi_desc(data);
        struct platform_msi_priv_data *priv_data;

        priv_data = desc->platform.msi_priv_data;

        priv_data->write_msg(desc, msg);
}

static void platform_msi_update_chip_ops(struct msi_domain_info *info)
{
        struct irq_chip *chip = info->chip;

        BUG_ON(!chip);
        if (!chip->irq_mask)
                chip->irq_mask = irq_chip_mask_parent;
        if (!chip->irq_unmask)
                chip->irq_unmask = irq_chip_unmask_parent;
        if (!chip->irq_eoi)
                chip->irq_eoi = irq_chip_eoi_parent;
        if (!chip->irq_set_affinity)
                chip->irq_set_affinity = msi_domain_set_affinity;
        if (!chip->irq_write_msi_msg)
                chip->irq_write_msi_msg = platform_msi_write_msg;
}

static void platform_msi_free_descs(struct device *dev, int base, int nvec)
{
        struct msi_desc *desc, *tmp;

        list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
                if (desc->platform.msi_index >= base &&
                    desc->platform.msi_index < (base + nvec)) {
                        list_del(&desc->list);
                        free_msi_entry(desc);
                }
        }
}

static int platform_msi_alloc_descs_with_irq(struct device *dev, int virq,
                                             int nvec,
                                             struct platform_msi_priv_data *data)

{
        struct msi_desc *desc;
        int i, base = 0;

        if (!list_empty(dev_to_msi_list(dev))) {
                desc = list_last_entry(dev_to_msi_list(dev),
                                       struct msi_desc, list);
                base = desc->platform.msi_index + 1;
        }

        for (i = 0; i < nvec; i++) {
                desc = alloc_msi_entry(dev, 1, NULL);
                if (!desc)
                        break;

                desc->platform.msi_priv_data = data;
                desc->platform.msi_index = base + i;
                desc->irq = virq ? virq + i : 0;

                list_add_tail(&desc->list, dev_to_msi_list(dev));
        }

        if (i != nvec) {
                /* Clean up the mess */
                platform_msi_free_descs(dev, base, nvec);

                return -ENOMEM;
        }

        return 0;
}

static int platform_msi_alloc_descs(struct device *dev, int nvec,
                                    struct platform_msi_priv_data *data)

{
        return platform_msi_alloc_descs_with_irq(dev, 0, nvec, data);
}

/**
 * platform_msi_create_irq_domain - Create a platform MSI interrupt domain
 * @fwnode:             Optional fwnode of the interrupt controller
 * @info:       MSI domain info
 * @parent:     Parent irq domain
 *
 * Updates the domain and chip ops and creates a platform MSI
 * interrupt domain.
 *
 * Returns:
 * A domain pointer or NULL in case of failure.
 */
struct irq_domain *platform_msi_create_irq_domain(struct fwnode_handle *fwnode,
                                                  struct msi_domain_info *info,
                                                  struct irq_domain *parent)
{
        struct irq_domain *domain;

        if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
                platform_msi_update_dom_ops(info);
        if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
                platform_msi_update_chip_ops(info);

        domain = msi_create_irq_domain(fwnode, info, parent);
        if (domain)
                domain->bus_token = DOMAIN_BUS_PLATFORM_MSI;

        return domain;
}

static struct platform_msi_priv_data *
platform_msi_alloc_priv_data(struct device *dev, unsigned int nvec,
                             irq_write_msi_msg_t write_msi_msg)
{
        struct platform_msi_priv_data *datap;
        /*
         * Limit the number of interrupts to 256 per device. Should we
         * need to bump this up, DEV_ID_SHIFT should be adjusted
         * accordingly (which would impact the max number of MSI
         * capable devices).
         */
        if (!dev->msi_domain || !write_msi_msg || !nvec || nvec > MAX_DEV_MSIS)
                return ERR_PTR(-EINVAL);

        if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {
                dev_err(dev, "Incompatible msi_domain, giving up\n");
                return ERR_PTR(-EINVAL);
        }

        /* Already had a helping of MSI? Greed... */
        if (!list_empty(dev_to_msi_list(dev)))
                return ERR_PTR(-EBUSY);

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

        datap->devid = ida_simple_get(&platform_msi_devid_ida,
                                      0, 1 << DEV_ID_SHIFT, GFP_KERNEL);
        if (datap->devid < 0) {
                int err = datap->devid;
                kfree(datap);
                return ERR_PTR(err);
        }

        datap->write_msg = write_msi_msg;
        datap->dev = dev;

        return datap;
}

static void platform_msi_free_priv_data(struct platform_msi_priv_data *data)
{
        ida_simple_remove(&platform_msi_devid_ida, data->devid);
        kfree(data);
}

/**
 * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
 * @dev:                The device for which to allocate interrupts
 * @nvec:               The number of interrupts to allocate
 * @write_msi_msg:      Callback to write an interrupt message for @dev
 *
 * Returns:
 * Zero for success, or an error code in case of failure
 */
int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
                                   irq_write_msi_msg_t write_msi_msg)
{
        struct platform_msi_priv_data *priv_data;
        int err;

        priv_data = platform_msi_alloc_priv_data(dev, nvec, write_msi_msg);
        if (IS_ERR(priv_data))
                return PTR_ERR(priv_data);

        err = platform_msi_alloc_descs(dev, nvec, priv_data);
        if (err)
                goto out_free_priv_data;

        err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);
        if (err)
                goto out_free_desc;

        return 0;

out_free_desc:
        platform_msi_free_descs(dev, 0, nvec);
out_free_priv_data:
        platform_msi_free_priv_data(priv_data);

        return err;
}
EXPORT_SYMBOL_GPL(platform_msi_domain_alloc_irqs);

/**
 * platform_msi_domain_free_irqs - Free MSI interrupts for @dev
 * @dev:        The device for which to free interrupts
 */
void platform_msi_domain_free_irqs(struct device *dev)
{
        if (!list_empty(dev_to_msi_list(dev))) {
                struct msi_desc *desc;

                desc = first_msi_entry(dev);
                platform_msi_free_priv_data(desc->platform.msi_priv_data);
        }

        msi_domain_free_irqs(dev->msi_domain, dev);
        platform_msi_free_descs(dev, 0, MAX_DEV_MSIS);
}
EXPORT_SYMBOL_GPL(platform_msi_domain_free_irqs);

/**
 * platform_msi_get_host_data - Query the private data associated with
 *                              a platform-msi domain
 * @domain:     The platform-msi domain
 *
 * Returns the private data provided when calling
 * platform_msi_create_device_domain.
 */
void *platform_msi_get_host_data(struct irq_domain *domain)
{
        struct platform_msi_priv_data *data = domain->host_data;
        return data->host_data;
}

/**
 * platform_msi_create_device_domain - Create a platform-msi domain
 *
 * @dev:                The device generating the MSIs
 * @nvec:               The number of MSIs that need to be allocated
 * @write_msi_msg:      Callback to write an interrupt message for @dev
 * @ops:                The hierarchy domain operations to use
 * @host_data:          Private data associated to this domain
 *
 * Returns an irqdomain for @nvec interrupts
 */
struct irq_domain *
platform_msi_create_device_domain(struct device *dev,
                                  unsigned int nvec,
                                  irq_write_msi_msg_t write_msi_msg,
                                  const struct irq_domain_ops *ops,
                                  void *host_data)
{
        struct platform_msi_priv_data *data;
        struct irq_domain *domain;
        int err;

        data = platform_msi_alloc_priv_data(dev, nvec, write_msi_msg);
        if (IS_ERR(data))
                return NULL;

        data->host_data = host_data;
        domain = irq_domain_create_hierarchy(dev->msi_domain, 0, nvec,
                                             of_node_to_fwnode(dev->of_node),
                                             ops, data);
        if (!domain)
                goto free_priv;

        err = msi_domain_prepare_irqs(domain->parent, dev, nvec, &data->arg);
        if (err)
                goto free_domain;

        return domain;

free_domain:
        irq_domain_remove(domain);
free_priv:
        platform_msi_free_priv_data(data);
        return NULL;
}

/**
 * platform_msi_domain_free - Free interrupts associated with a platform-msi
 *                            domain
 *
 * @domain:     The platform-msi domain
 * @virq:       The base irq from which to perform the free operation
 * @nvec:       How many interrupts to free from @virq
 */
void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq,
                              unsigned int nvec)
{
        struct platform_msi_priv_data *data = domain->host_data;
        struct msi_desc *desc;
        for_each_msi_entry(desc, data->dev) {
                if (WARN_ON(!desc->irq || desc->nvec_used != 1))
                        return;
                if (!(desc->irq >= virq && desc->irq < (virq + nvec)))
                        continue;

                irq_domain_free_irqs_common(domain, desc->irq, 1);
        }
}

/**
 * platform_msi_domain_alloc - Allocate interrupts associated with
 *                             a platform-msi domain
 *
 * @domain:     The platform-msi domain
 * @virq:       The base irq from which to perform the allocate operation
 * @nvec:       How many interrupts to free from @virq
 *
 * Return 0 on success, or an error code on failure. Must be called
 * with irq_domain_mutex held (which can only be done as part of a
 * top-level interrupt allocation).
 */
int platform_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
                              unsigned int nr_irqs)
{
        struct platform_msi_priv_data *data = domain->host_data;
        int err;

        err = platform_msi_alloc_descs_with_irq(data->dev, virq, nr_irqs, data);
        if (err)
                return err;

        err = msi_domain_populate_irqs(domain->parent, data->dev,
                                       virq, nr_irqs, &data->arg);
        if (err)
                platform_msi_domain_free(domain, virq, nr_irqs);

        return err;
}