hsi.c

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/*
 * HSI core.
 *
 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
 *
 * Contact: Carlos Chinea <[email protected]>
 *
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <linux/hsi/hsi.h>
#include <linux/compiler.h>
#include <linux/list.h>
#include <linux/kobject.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/notifier.h>
#include "hsi_core.h"

static ssize_t modalias_show(struct device *dev,
            struct device_attribute *a __maybe_unused, char *buf)
{
    return sprintf(buf, "hsi:%s\n", dev_name(dev));
}

static struct device_attribute hsi_bus_dev_attrs[] = {
    __ATTR_RO(modalias),
    __ATTR_NULL,
};

static int hsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));

    return 0;
}

static int hsi_bus_match(struct device *dev, struct device_driver *driver)
{
    return strcmp(dev_name(dev), driver->name) == 0;
}

static struct bus_type hsi_bus_type = {
    .name       = "hsi",
    .dev_attrs  = hsi_bus_dev_attrs,
    .match      = hsi_bus_match,
    .uevent     = hsi_bus_uevent,
};

static void hsi_client_release(struct device *dev)
{
    kfree(to_hsi_client(dev));
}

static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
{
    struct hsi_client *cl;

    cl = kzalloc(sizeof(*cl), GFP_KERNEL);
    if (!cl)
        return;
    cl->tx_cfg = info->tx_cfg;
    cl->rx_cfg = info->rx_cfg;
    cl->device.bus = &hsi_bus_type;
    cl->device.parent = &port->device;
    cl->device.release = hsi_client_release;
    dev_set_name(&cl->device, info->name);
    cl->device.platform_data = info->platform_data;
    if (info->archdata)
        cl->device.archdata = *info->archdata;
    if (device_register(&cl->device) < 0) {
        pr_err("hsi: failed to register client: %s\n", info->name);
        put_device(&cl->device);
    }
}

static void hsi_scan_board_info(struct hsi_controller *hsi)
{
    struct hsi_cl_info *cl_info;
    struct hsi_port *p;

    list_for_each_entry(cl_info, &hsi_board_list, list)
        if (cl_info->info.hsi_id == hsi->id) {
            p = hsi_find_port_num(hsi, cl_info->info.port);
            if (!p)
                continue;
            hsi_new_client(p, &cl_info->info);
        }
}

static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
{
    device_unregister(dev);

    return 0;
}

static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
{
    device_for_each_child(dev, NULL, hsi_remove_client);
    device_unregister(dev);

    return 0;
}

static void hsi_controller_release(struct device *dev)
{
    struct hsi_controller *hsi = to_hsi_controller(dev);

    kfree(hsi->port);
    kfree(hsi);
}

static void hsi_port_release(struct device *dev)
{
    kfree(to_hsi_port(dev));
}

void hsi_unregister_controller(struct hsi_controller *hsi)
{
    device_for_each_child(&hsi->device, NULL, hsi_remove_port);
    device_unregister(&hsi->device);
}
EXPORT_SYMBOL_GPL(hsi_unregister_controller);

int hsi_register_controller(struct hsi_controller *hsi)
{
    unsigned int i;
    int err;

    err = device_add(&hsi->device);
    if (err < 0)
        return err;
    for (i = 0; i < hsi->num_ports; i++) {
        hsi->port[i]->device.parent = &hsi->device;
        err = device_add(&hsi->port[i]->device);
        if (err < 0)
            goto out;
    }
    /* Populate HSI bus with HSI clients */
    hsi_scan_board_info(hsi);

    return 0;
out:
    while (i-- > 0)
        device_del(&hsi->port[i]->device);
    device_del(&hsi->device);

    return err;
}
EXPORT_SYMBOL_GPL(hsi_register_controller);

int hsi_register_client_driver(struct hsi_client_driver *drv)
{
    drv->driver.bus = &hsi_bus_type;

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

static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
{
    return 0;
}

static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
{
    return 0;
}

void hsi_put_controller(struct hsi_controller *hsi)
{
    unsigned int i;

    if (!hsi)
        return;

    for (i = 0; i < hsi->num_ports; i++)
        if (hsi->port && hsi->port[i])
            put_device(&hsi->port[i]->device);
    put_device(&hsi->device);
}
EXPORT_SYMBOL_GPL(hsi_put_controller);

struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
{
    struct hsi_controller   *hsi;
    struct hsi_port     **port;
    unsigned int        i;

    if (!n_ports)
        return NULL;

    hsi = kzalloc(sizeof(*hsi), flags);
    if (!hsi)
        return NULL;
    port = kzalloc(sizeof(*port)*n_ports, flags);
    if (!port) {
        kfree(hsi);
        return NULL;
    }
    hsi->num_ports = n_ports;
    hsi->port = port;
    hsi->device.release = hsi_controller_release;
    device_initialize(&hsi->device);

    for (i = 0; i < n_ports; i++) {
        port[i] = kzalloc(sizeof(**port), flags);
        if (port[i] == NULL)
            goto out;
        port[i]->num = i;
        port[i]->async = hsi_dummy_msg;
        port[i]->setup = hsi_dummy_cl;
        port[i]->flush = hsi_dummy_cl;
        port[i]->start_tx = hsi_dummy_cl;
        port[i]->stop_tx = hsi_dummy_cl;
        port[i]->release = hsi_dummy_cl;
        mutex_init(&port[i]->lock);
        ATOMIC_INIT_NOTIFIER_HEAD(&port[i]->n_head);
        dev_set_name(&port[i]->device, "port%d", i);
        hsi->port[i]->device.release = hsi_port_release;
        device_initialize(&hsi->port[i]->device);
    }

    return hsi;
out:
    hsi_put_controller(hsi);

    return NULL;
}
EXPORT_SYMBOL_GPL(hsi_alloc_controller);

void hsi_free_msg(struct hsi_msg *msg)
{
    if (!msg)
        return;
    sg_free_table(&msg->sgt);
    kfree(msg);
}
EXPORT_SYMBOL_GPL(hsi_free_msg);

struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
{
    struct hsi_msg *msg;
    int err;

    msg = kzalloc(sizeof(*msg), flags);
    if (!msg)
        return NULL;

    if (!nents)
        return msg;

    err = sg_alloc_table(&msg->sgt, nents, flags);
    if (unlikely(err)) {
        kfree(msg);
        msg = NULL;
    }

    return msg;
}
EXPORT_SYMBOL_GPL(hsi_alloc_msg);

int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
{
    struct hsi_port *port = hsi_get_port(cl);

    if (!hsi_port_claimed(cl))
        return -EACCES;

    WARN_ON_ONCE(!msg->destructor || !msg->complete);
    msg->cl = cl;

    return port->async(msg);
}
EXPORT_SYMBOL_GPL(hsi_async);

int hsi_claim_port(struct hsi_client *cl, unsigned int share)
{
    struct hsi_port *port = hsi_get_port(cl);
    int err = 0;

    mutex_lock(&port->lock);
    if ((port->claimed) && (!port->shared || !share)) {
        err = -EBUSY;
        goto out;
    }
    if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
        err = -ENODEV;
        goto out;
    }
    port->claimed++;
    port->shared = !!share;
    cl->pclaimed = 1;
out:
    mutex_unlock(&port->lock);

    return err;
}
EXPORT_SYMBOL_GPL(hsi_claim_port);

void hsi_release_port(struct hsi_client *cl)
{
    struct hsi_port *port = hsi_get_port(cl);

    mutex_lock(&port->lock);
    /* Allow HW driver to do some cleanup */
    port->release(cl);
    if (cl->pclaimed)
        port->claimed--;
    BUG_ON(port->claimed < 0);
    cl->pclaimed = 0;
    if (!port->claimed)
        port->shared = 0;
    module_put(to_hsi_controller(port->device.parent)->owner);
    mutex_unlock(&port->lock);
}
EXPORT_SYMBOL_GPL(hsi_release_port);

static int hsi_event_notifier_call(struct notifier_block *nb,
                unsigned long event, void *data __maybe_unused)
{
    struct hsi_client *cl = container_of(nb, struct hsi_client, nb);

    (*cl->ehandler)(cl, event);

    return 0;
}

int hsi_register_port_event(struct hsi_client *cl,
            void (*handler)(struct hsi_client *, unsigned long))
{
    struct hsi_port *port = hsi_get_port(cl);

    if (!handler || cl->ehandler)
        return -EINVAL;
    if (!hsi_port_claimed(cl))
        return -EACCES;
    cl->ehandler = handler;
    cl->nb.notifier_call = hsi_event_notifier_call;

    return atomic_notifier_chain_register(&port->n_head, &cl->nb);
}
EXPORT_SYMBOL_GPL(hsi_register_port_event);

int hsi_unregister_port_event(struct hsi_client *cl)
{
    struct hsi_port *port = hsi_get_port(cl);
    int err;

    WARN_ON(!hsi_port_claimed(cl));

    err = atomic_notifier_chain_unregister(&port->n_head, &cl->nb);
    if (!err)
        cl->ehandler = NULL;

    return err;
}
EXPORT_SYMBOL_GPL(hsi_unregister_port_event);

int hsi_event(struct hsi_port *port, unsigned long event)
{
    return atomic_notifier_call_chain(&port->n_head, event, NULL);
}
EXPORT_SYMBOL_GPL(hsi_event);

static int __init hsi_init(void)
{
    return bus_register(&hsi_bus_type);
}
postcore_initcall(hsi_init);

static void __exit hsi_exit(void)
{
    bus_unregister(&hsi_bus_type);
}
module_exit(hsi_exit);

MODULE_AUTHOR("Carlos Chinea <[email protected]>");
MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
MODULE_LICENSE("GPL v2");