/*
 * Core maple bus functionality
 *
 *  Copyright (C) 2007 Adrian McMenamin
 *
 * Based on 2.4 code by:
 *
 *  Copyright (C) 2000-2001 YAEGASHI Takeshi
 *  Copyright (C) 2001 M. R. Brown
 *  Copyright (C) 2001 Paul Mundt
 *
 * and others.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/maple.h>
#include <linux/dma-mapping.h>
#include <asm/cacheflush.h>
#include <asm/dma.h>
#include <asm/io.h>
#include <asm/mach/dma.h>
#include <asm/mach/sysasic.h>
#include <asm/mach/maple.h>

MODULE_AUTHOR("Yaegshi Takeshi, Paul Mundt, M.R. Brown, Adrian McMenamin");
MODULE_DESCRIPTION("Maple bus driver for Dreamcast");
MODULE_LICENSE("GPL v2");
MODULE_SUPPORTED_DEVICE("{{SEGA, Dreamcast/Maple}}");

static void maple_dma_handler(struct work_struct *work);
static void maple_vblank_handler(struct work_struct *work);

static DECLARE_WORK(maple_dma_process, maple_dma_handler);
static DECLARE_WORK(maple_vblank_process, maple_vblank_handler);

static LIST_HEAD(maple_waitq);
static LIST_HEAD(maple_sentq);

static DEFINE_MUTEX(maple_list_lock);

static struct maple_driver maple_dummy_driver;
static struct device maple_bus;
static int subdevice_map[MAPLE_PORTS];
static unsigned long *maple_sendbuf, *maple_sendptr, *maple_lastptr;
static unsigned long maple_pnp_time;
static int started, scanning, liststatus;
static struct kmem_cache *maple_queue_cache;

struct maple_device_specify {
       int port;
       int unit;
};

/**
 *  maple_driver_register - register a device driver
 *  automatically makes the driver bus a maple bus
 *  @drv: the driver to be registered
 */
int maple_driver_register(struct device_driver *drv)
{
       if (!drv)
               return -EINVAL;
       drv->bus = &maple_bus_type;
       return driver_register(drv);
}
EXPORT_SYMBOL_GPL(maple_driver_register);

/* set hardware registers to enable next round of dma */
static void maplebus_dma_reset(void)
{
       ctrl_outl(MAPLE_MAGIC, MAPLE_RESET);
       /* set trig type to 0 for software trigger, 1 for hardware (VBLANK) */
       ctrl_outl(1, MAPLE_TRIGTYPE);
       ctrl_outl(MAPLE_2MBPS | MAPLE_TIMEOUT(50000), MAPLE_SPEED);
       ctrl_outl(PHYSADDR(maple_sendbuf), MAPLE_DMAADDR);
       ctrl_outl(1, MAPLE_ENABLE);
}

/**
 * maple_getcond_callback - setup handling MAPLE_COMMAND_GETCOND
 * @dev: device responding
 * @callback: handler callback
 * @interval: interval in jiffies between callbacks
 * @function: the function code for the device
 */
void maple_getcond_callback(struct maple_device *dev,
                           void (*callback) (struct mapleq * mq),
                           unsigned long interval, unsigned long function)
{
       dev->callback = callback;
       dev->interval = interval;
       dev->function = cpu_to_be32(function);
       dev->when = jiffies;
}
EXPORT_SYMBOL_GPL(maple_getcond_callback);

static int maple_dma_done(void)
{
       return (ctrl_inl(MAPLE_STATE) & 1) == 0;
}

static void maple_release_device(struct device *dev)
{
       if (dev->type) {
               kfree(dev->type->name);
               kfree(dev->type);
       }
}

/**
 * maple_add_packet - add a single instruction to the queue
 * @mq: instruction to add to waiting queue
 */
void maple_add_packet(struct mapleq *mq)
{
       mutex_lock(&maple_list_lock);
       list_add(&mq->list, &maple_waitq);
       mutex_unlock(&maple_list_lock);
}
EXPORT_SYMBOL_GPL(maple_add_packet);

static struct mapleq *maple_allocq(struct maple_device *dev)
{
       struct mapleq *mq;

       mq = kmalloc(sizeof(*mq), GFP_KERNEL);
       if (!mq)
               return NULL;

       mq->dev = dev;
       mq->recvbufdcsp = kmem_cache_zalloc(maple_queue_cache, GFP_KERNEL);
       mq->recvbuf = (void *) P2SEGADDR(mq->recvbufdcsp);
       if (!mq->recvbuf) {
               kfree(mq);
               return NULL;
       }

       return mq;
}

static struct maple_device *maple_alloc_dev(int port, int unit)
{
       struct maple_device *dev;

       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
       if (!dev)
               return NULL;

       dev->port = port;
       dev->unit = unit;
       dev->mq = maple_allocq(dev);

       if (!dev->mq) {
               kfree(dev);
               return NULL;
       }

       return dev;
}

static void maple_free_dev(struct maple_device *mdev)
{
       if (!mdev)
               return;
       if (mdev->mq) {
               kmem_cache_free(maple_queue_cache, mdev->mq->recvbufdcsp);
               kfree(mdev->mq);
       }
       kfree(mdev);
}

/* process the command queue into a maple command block
 * terminating command has bit 32 of first long set to 0
 */
static void maple_build_block(struct mapleq *mq)
{
       int port, unit, from, to, len;
       unsigned long *lsendbuf = mq->sendbuf;

       port = mq->dev->port & 3;
       unit = mq->dev->unit;
       len = mq->length;
       from = port << 6;
       to = (port << 6) | (unit > 0 ? (1 << (unit - 1)) & 0x1f : 0x20);

       *maple_lastptr &= 0x7fffffff;
       maple_lastptr = maple_sendptr;

       *maple_sendptr++ = (port << 16) | len | 0x80000000;
       *maple_sendptr++ = PHYSADDR(mq->recvbuf);
       *maple_sendptr++ =
           mq->command | (to << 8) | (from << 16) | (len << 24);

       while (len-- > 0)
               *maple_sendptr++ = *lsendbuf++;
}

/* build up command queue */
static void maple_send(void)
{
       int i;
       int maple_packets;
       struct mapleq *mq, *nmq;

       if (!list_empty(&maple_sentq))
               return;
       if (list_empty(&maple_waitq) || !maple_dma_done())
               return;
       maple_packets = 0;
       maple_sendptr = maple_lastptr = maple_sendbuf;
       list_for_each_entry_safe(mq, nmq, &maple_waitq, list) {
               maple_build_block(mq);
               list_move(&mq->list, &maple_sentq);
               if (maple_packets++ > MAPLE_MAXPACKETS)
                       break;
       }
       if (maple_packets > 0) {
               for (i = 0; i < (1 << MAPLE_DMA_PAGES); i++)
                       dma_cache_sync(0, maple_sendbuf + i * PAGE_SIZE,
                                      PAGE_SIZE, DMA_BIDIRECTIONAL);
       }
}

static int attach_matching_maple_driver(struct device_driver *driver,
                                       void *devptr)
{
       struct maple_driver *maple_drv;
       struct maple_device *mdev;

       mdev = devptr;
       maple_drv = to_maple_driver(driver);
       if (mdev->devinfo.function & be32_to_cpu(maple_drv->function)) {
               if (maple_drv->connect(mdev) == 0) {
                       mdev->driver = maple_drv;
                       return 1;
               }
       }
       return 0;
}

static void maple_detach_driver(struct maple_device *mdev)
{
       if (!mdev)
               return;
       if (mdev->driver) {
               if (mdev->driver->disconnect)
                       mdev->driver->disconnect(mdev);
       }
       mdev->driver = NULL;
       if (mdev->registered) {
               maple_release_device(&mdev->dev);
               device_unregister(&mdev->dev);
       }
       mdev->registered = 0;
       maple_free_dev(mdev);
}

/* process initial MAPLE_COMMAND_DEVINFO for each device or port */
static void maple_attach_driver(struct maple_device *dev)
{
       char *p;

       char *recvbuf;
       unsigned long function;
       int matched, retval;

       recvbuf = dev->mq->recvbuf;
       memcpy(&dev->devinfo, recvbuf + 4, sizeof(dev->devinfo));
       memcpy(dev->product_name, dev->devinfo.product_name, 30);
       memcpy(dev->product_licence, dev->devinfo.product_licence, 60);
       dev->product_name[30] = '\0';
       dev->product_licence[60] = '\0';

       for (p = dev->product_name + 29; dev->product_name <= p; p--)
               if (*p == ' ')
                       *p = '\0';
               else
                       break;

       for (p = dev->product_licence + 59; dev->product_licence <= p; p--)
               if (*p == ' ')
                       *p = '\0';
               else
                       break;

       function = be32_to_cpu(dev->devinfo.function);

       if (function > 0x200) {
               /* Do this silently - as not a real device */
               function = 0;
               dev->driver = &maple_dummy_driver;
               sprintf(dev->dev.bus_id, "%d:0.port", dev->port);
       } else {
               printk(KERN_INFO
                      "Maple bus at (%d, %d): Connected function 0x%lX\n",
                      dev->port, dev->unit, function);

               matched =
                   bus_for_each_drv(&maple_bus_type, NULL, dev,
                                    attach_matching_maple_driver);

               if (matched == 0) {
                       /* Driver does not exist yet */
                       printk(KERN_INFO
                              "No maple driver found for this device\n");
                       dev->driver = &maple_dummy_driver;
               }

               sprintf(dev->dev.bus_id, "%d:0%d.%lX", dev->port,
                       dev->unit, function);
       }
       dev->function = function;
       dev->dev.bus = &maple_bus_type;
       dev->dev.parent = &maple_bus;
       dev->dev.release = &maple_release_device;
       retval = device_register(&dev->dev);
       if (retval) {
               printk(KERN_INFO
                      "Maple bus: Attempt to register device (%x, %x) failed.\n",
                      dev->port, dev->unit);
               maple_free_dev(dev);
       }
       dev->registered = 1;
}

/*
 * if device has been registered for the given
 * port and unit then return 1 - allows identification
 * of which devices need to be attached or detached
 */
static int detach_maple_device(struct device *device, void *portptr)
{
       struct maple_device_specify *ds;
       struct maple_device *mdev;

       ds = portptr;
       mdev = to_maple_dev(device);
       if (mdev->port == ds->port && mdev->unit == ds->unit)
               return 1;
       return 0;
}

static int setup_maple_commands(struct device *device, void *ignored)
{
       struct maple_device *maple_dev = to_maple_dev(device);

       if ((maple_dev->interval > 0)
           && time_after(jiffies, maple_dev->when)) {
               maple_dev->when = jiffies + maple_dev->interval;
               maple_dev->mq->command = MAPLE_COMMAND_GETCOND;
               maple_dev->mq->sendbuf = &maple_dev->function;
               maple_dev->mq->length = 1;
               maple_add_packet(maple_dev->mq);
               liststatus++;
       } else {
               if (time_after(jiffies, maple_pnp_time)) {
                       maple_dev->mq->command = MAPLE_COMMAND_DEVINFO;
                       maple_dev->mq->length = 0;
                       maple_add_packet(maple_dev->mq);
                       liststatus++;
               }
       }

       return 0;
}

/* VBLANK bottom half - implemented via workqueue */
static void maple_vblank_handler(struct work_struct *work)
{
       if (!maple_dma_done())
               return;
       if (!list_empty(&maple_sentq))
               return;
       ctrl_outl(0, MAPLE_ENABLE);
       liststatus = 0;
       bus_for_each_dev(&maple_bus_type, NULL, NULL,
                        setup_maple_commands);
       if (time_after(jiffies, maple_pnp_time))
               maple_pnp_time = jiffies + MAPLE_PNP_INTERVAL;
       if (liststatus && list_empty(&maple_sentq)) {
               INIT_LIST_HEAD(&maple_sentq);
               maple_send();
       }
       maplebus_dma_reset();
}

/* handle devices added via hotplugs - placing them on queue for DEVINFO*/
static void maple_map_subunits(struct maple_device *mdev, int submask)
{
       int retval, k, devcheck;
       struct maple_device *mdev_add;
       struct maple_device_specify ds;

       for (k = 0; k < 5; k++) {
               ds.port = mdev->port;
               ds.unit = k + 1;
               retval =
                   bus_for_each_dev(&maple_bus_type, NULL, &ds,
                                    detach_maple_device);
               if (retval) {
                       submask = submask >> 1;
                       continue;
               }
               devcheck = submask & 0x01;
               if (devcheck) {
                       mdev_add = maple_alloc_dev(mdev->port, k + 1);
                       if (!mdev_add)
                               return;
                       mdev_add->mq->command = MAPLE_COMMAND_DEVINFO;
                       mdev_add->mq->length = 0;
                       maple_add_packet(mdev_add->mq);
                       scanning = 1;
               }
               submask = submask >> 1;
       }
}

/* mark a device as removed */
static void maple_clean_submap(struct maple_device *mdev)
{
       int killbit;

       killbit = (mdev->unit > 0 ? (1 << (mdev->unit - 1)) & 0x1f : 0x20);
       killbit = ~killbit;
       killbit &= 0xFF;
       subdevice_map[mdev->port] = subdevice_map[mdev->port] & killbit;
}

/* handle empty port or hotplug removal */
static void maple_response_none(struct maple_device *mdev,
                               struct mapleq *mq)
{
       if (mdev->unit != 0) {
               list_del(&mq->list);
               maple_clean_submap(mdev);
               printk(KERN_INFO
                      "Maple bus device detaching at (%d, %d)\n",
                      mdev->port, mdev->unit);
               maple_detach_driver(mdev);
               return;
       }
       if (!started) {
               printk(KERN_INFO "No maple devices attached to port %d\n",
                      mdev->port);
               return;
       }
       maple_clean_submap(mdev);
}

/* preprocess hotplugs or scans */
static void maple_response_devinfo(struct maple_device *mdev,
                                  char *recvbuf)
{
       char submask;
       if ((!started) || (scanning == 2)) {
               maple_attach_driver(mdev);
               return;
       }
       if (mdev->unit == 0) {
               submask = recvbuf[2] & 0x1F;
               if (submask ^ subdevice_map[mdev->port]) {
                       maple_map_subunits(mdev, submask);
                       subdevice_map[mdev->port] = submask;
               }
       }
}

/* maple dma end bottom half - implemented via workqueue */
static void maple_dma_handler(struct work_struct *work)
{
       struct mapleq *mq, *nmq;
       struct maple_device *dev;
       char *recvbuf;
       enum maple_code code;

       if (!maple_dma_done())
               return;
       ctrl_outl(0, MAPLE_ENABLE);
       if (!list_empty(&maple_sentq)) {
               list_for_each_entry_safe(mq, nmq, &maple_sentq, list) {
                       recvbuf = mq->recvbuf;
                       code = recvbuf[0];
                       dev = mq->dev;
                       switch (code) {
                       case MAPLE_RESPONSE_NONE:
                               maple_response_none(dev, mq);
                               break;

                       case MAPLE_RESPONSE_DEVINFO:
                               maple_response_devinfo(dev, recvbuf);
                               break;

                       case MAPLE_RESPONSE_DATATRF:
                               if (dev->callback)
                                       dev->callback(mq);
                               break;

                       case MAPLE_RESPONSE_FILEERR:
                       case MAPLE_RESPONSE_AGAIN:
                       case MAPLE_RESPONSE_BADCMD:
                       case MAPLE_RESPONSE_BADFUNC:
                               printk(KERN_DEBUG
                                      "Maple non-fatal error 0x%X\n",
                                      code);
                               break;

                       case MAPLE_RESPONSE_ALLINFO:
                               printk(KERN_DEBUG
                                      "Maple - extended device information not supported\n");
                               break;

                       case MAPLE_RESPONSE_OK:
                               break;

                       default:
                               break;
                       }
               }
               INIT_LIST_HEAD(&maple_sentq);
               if (scanning == 1) {
                       maple_send();
                       scanning = 2;
               } else
                       scanning = 0;

               if (started == 0)
                       started = 1;
       }
       maplebus_dma_reset();
}

static irqreturn_t maplebus_dma_interrupt(int irq, void *dev_id)
{
       /* Load everything into the bottom half */
       schedule_work(&maple_dma_process);
       return IRQ_HANDLED;
}

static irqreturn_t maplebus_vblank_interrupt(int irq, void *dev_id)
{
       schedule_work(&maple_vblank_process);
       return IRQ_HANDLED;
}

static struct irqaction maple_dma_irq = {
       .name = "maple bus DMA handler",
       .handler = maplebus_dma_interrupt,
       .flags = IRQF_SHARED,
};

static struct irqaction maple_vblank_irq = {
       .name = "maple bus VBLANK handler",
       .handler = maplebus_vblank_interrupt,
       .flags = IRQF_SHARED,
};

static int maple_set_dma_interrupt_handler(void)
{
       return setup_irq(HW_EVENT_MAPLE_DMA, &maple_dma_irq);
}

static int maple_set_vblank_interrupt_handler(void)
{
       return setup_irq(HW_EVENT_VSYNC, &maple_vblank_irq);
}

static int maple_get_dma_buffer(void)
{
       maple_sendbuf =
           (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                     MAPLE_DMA_PAGES);
       if (!maple_sendbuf)
               return -ENOMEM;
       return 0;
}

static int match_maple_bus_driver(struct device *devptr,
                                 struct device_driver *drvptr)
{
       struct maple_driver *maple_drv;
       struct maple_device *maple_dev;

       maple_drv = container_of(drvptr, struct maple_driver, drv);
       maple_dev = container_of(devptr, struct maple_device, dev);
       /* Trap empty port case */
       if (maple_dev->devinfo.function == 0xFFFFFFFF)
               return 0;
       else if (maple_dev->devinfo.function &
                be32_to_cpu(maple_drv->function))
               return 1;
       return 0;
}

static int maple_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
       return 0;
}

static void maple_bus_release(struct device *dev)
{
}

static struct maple_driver maple_dummy_driver = {
       .drv = {
               .name = "maple_dummy_driver",
               .bus =  &maple_bus_type,
       },
};

struct bus_type maple_bus_type = {
       .name =         "maple",
       .match =        match_maple_bus_driver,
       .uevent =       maple_bus_uevent,
};
EXPORT_SYMBOL_GPL(maple_bus_type);

static struct device maple_bus = {
       .bus_id = "maple",
       .release = maple_bus_release,
};

static int __init maple_bus_init(void)
{
       int retval, i;
       struct maple_device *mdev[MAPLE_PORTS];
       ctrl_outl(0, MAPLE_STATE);

       retval = device_register(&maple_bus);
       if (retval)
               goto cleanup;

       retval = bus_register(&maple_bus_type);
       if (retval)
               goto cleanup_device;

       retval = driver_register(&maple_dummy_driver.drv);

       if (retval)
               goto cleanup_bus;

       /* allocate memory for maple bus dma */
       retval = maple_get_dma_buffer();
       if (retval) {
               printk(KERN_INFO
                      "Maple bus: Failed to allocate Maple DMA buffers\n");
               goto cleanup_basic;
       }

       /* set up DMA interrupt handler */
       retval = maple_set_dma_interrupt_handler();
       if (retval) {
               printk(KERN_INFO
                      "Maple bus: Failed to grab maple DMA IRQ\n");
               goto cleanup_dma;
       }

       /* set up VBLANK interrupt handler */
       retval = maple_set_vblank_interrupt_handler();
       if (retval) {
               printk(KERN_INFO "Maple bus: Failed to grab VBLANK IRQ\n");
               goto cleanup_irq;
       }

       maple_queue_cache =
           kmem_cache_create("maple_queue_cache", 0x400, 0,
                             SLAB_HWCACHE_ALIGN, NULL);

       if (!maple_queue_cache)
               goto cleanup_bothirqs;

       /* setup maple ports */
       for (i = 0; i < MAPLE_PORTS; i++) {
               mdev[i] = maple_alloc_dev(i, 0);
               if (!mdev[i]) {
                       while (i-- > 0)
                               maple_free_dev(mdev[i]);
                       goto cleanup_cache;
               }
               mdev[i]->registered = 0;
               mdev[i]->mq->command = MAPLE_COMMAND_DEVINFO;
               mdev[i]->mq->length = 0;
               maple_attach_driver(mdev[i]);
               maple_add_packet(mdev[i]->mq);
               subdevice_map[i] = 0;
       }

       /* setup maplebus hardware */
       maplebus_dma_reset();

       /* initial detection */
       maple_send();

       maple_pnp_time = jiffies;

       printk(KERN_INFO "Maple bus core now registered.\n");

       return 0;

cleanup_cache:
       kmem_cache_destroy(maple_queue_cache);

cleanup_bothirqs:
       free_irq(HW_EVENT_VSYNC, 0);

cleanup_irq:
       free_irq(HW_EVENT_MAPLE_DMA, 0);

cleanup_dma:
       free_pages((unsigned long) maple_sendbuf, MAPLE_DMA_PAGES);

cleanup_basic:
       driver_unregister(&maple_dummy_driver.drv);

cleanup_bus:
       bus_unregister(&maple_bus_type);

cleanup_device:
       device_unregister(&maple_bus);

cleanup:
       printk(KERN_INFO "Maple bus registration failed\n");
       return retval;
}
subsys_initcall(maple_bus_init);