nfs: Panic when commit fails

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / ps3 / ps3-vuart.c

/*
 *  PS3 virtual uart
 *
 *  Copyright (C) 2006 Sony Computer Entertainment Inc.
 *  Copyright 2006 Sony Corp.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
#include <asm/ps3.h>

#include <asm/firmware.h>
#include <asm/lv1call.h>

#include "vuart.h"

MODULE_AUTHOR("Sony Corporation");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("PS3 vuart");

/**
 * vuart - An inter-partition data link service.
 *  port 0: PS3 AV Settings.
 *  port 2: PS3 System Manager.
 *
 * The vuart provides a bi-directional byte stream data link between logical
 * partitions.  Its primary role is as a communications link between the guest
 * OS and the system policy module.  The current HV does not support any
 * connections other than those listed.
 */

enum {PORT_COUNT = 3,};

enum vuart_param {
        PARAM_TX_TRIGGER = 0,
        PARAM_RX_TRIGGER = 1,
        PARAM_INTERRUPT_MASK = 2,
        PARAM_RX_BUF_SIZE = 3, /* read only */
        PARAM_RX_BYTES = 4, /* read only */
        PARAM_TX_BUF_SIZE = 5, /* read only */
        PARAM_TX_BYTES = 6, /* read only */
        PARAM_INTERRUPT_STATUS = 7, /* read only */
};

enum vuart_interrupt_bit {
        INTERRUPT_BIT_TX = 0,
        INTERRUPT_BIT_RX = 1,
        INTERRUPT_BIT_DISCONNECT = 2,
};

enum vuart_interrupt_mask {
        INTERRUPT_MASK_TX = 1,
        INTERRUPT_MASK_RX = 2,
        INTERRUPT_MASK_DISCONNECT = 4,
};

/**
 * struct ps3_vuart_port_priv - private vuart device data.
 */

struct ps3_vuart_port_priv {
        u64 interrupt_mask;

        struct {
                spinlock_t lock;
                struct list_head head;
        } tx_list;
        struct {
                struct ps3_vuart_work work;
                unsigned long bytes_held;
                spinlock_t lock;
                struct list_head head;
        } rx_list;
        struct ps3_vuart_stats stats;
};

static struct ps3_vuart_port_priv *to_port_priv(
        struct ps3_system_bus_device *dev)
{
        BUG_ON(!dev);
        BUG_ON(!dev->driver_priv);
        return (struct ps3_vuart_port_priv *)dev->driver_priv;
}

/**
 * struct ports_bmp - bitmap indicating ports needing service.
 *
 * A 256 bit read only bitmap indicating ports needing service.  Do not write
 * to these bits.  Must not cross a page boundary.
 */

struct ports_bmp {
        u64 status;
        u64 unused[3];
} __attribute__((aligned(32)));

#define dump_ports_bmp(_b) _dump_ports_bmp(_b, __func__, __LINE__)
static void __maybe_unused _dump_ports_bmp(
        const struct ports_bmp *bmp, const char *func, int line)
{
        pr_debug("%s:%d: ports_bmp: %016llxh\n", func, line, bmp->status);
}

#define dump_port_params(_b) _dump_port_params(_b, __func__, __LINE__)
static void __maybe_unused _dump_port_params(unsigned int port_number,
        const char *func, int line)
{
#if defined(DEBUG)
        static const char *strings[] = {
                "tx_trigger      ",
                "rx_trigger      ",
                "interrupt_mask  ",
                "rx_buf_size     ",
                "rx_bytes        ",
                "tx_buf_size     ",
                "tx_bytes        ",
                "interrupt_status",
        };
        int result;
        unsigned int i;
        u64 value;

        for (i = 0; i < ARRAY_SIZE(strings); i++) {
                result = lv1_get_virtual_uart_param(port_number, i, &value);

                if (result) {
                        pr_debug("%s:%d: port_%u: %s failed: %s\n", func, line,
                                port_number, strings[i], ps3_result(result));
                        continue;
                }
                pr_debug("%s:%d: port_%u: %s = %lxh\n",
                        func, line, port_number, strings[i], value);
        }
#endif
}

struct vuart_triggers {
        unsigned long rx;
        unsigned long tx;
};

int ps3_vuart_get_triggers(struct ps3_system_bus_device *dev,
        struct vuart_triggers *trig)
{
        int result;
        u64 size;
        u64 val;
        u64 tx;

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_TX_TRIGGER, &tx);
        trig->tx = tx;

        if (result) {
                dev_dbg(&dev->core, "%s:%d: tx_trigger failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_RX_BUF_SIZE, &size);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: tx_buf_size failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_RX_TRIGGER, &val);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: rx_trigger failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        trig->rx = size - val;

        dev_dbg(&dev->core, "%s:%d: tx %lxh, rx %lxh\n", __func__, __LINE__,
                trig->tx, trig->rx);

        return result;
}

int ps3_vuart_set_triggers(struct ps3_system_bus_device *dev, unsigned int tx,
        unsigned int rx)
{
        int result;
        u64 size;

        result = lv1_set_virtual_uart_param(dev->port_number,
                PARAM_TX_TRIGGER, tx);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: tx_trigger failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_RX_BUF_SIZE, &size);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: tx_buf_size failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        result = lv1_set_virtual_uart_param(dev->port_number,
                PARAM_RX_TRIGGER, size - rx);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: rx_trigger failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        dev_dbg(&dev->core, "%s:%d: tx %xh, rx %xh\n", __func__, __LINE__,
                tx, rx);

        return result;
}

static int ps3_vuart_get_rx_bytes_waiting(struct ps3_system_bus_device *dev,
        u64 *bytes_waiting)
{
        int result;

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_RX_BYTES, bytes_waiting);

        if (result)
                dev_dbg(&dev->core, "%s:%d: rx_bytes failed: %s\n",
                        __func__, __LINE__, ps3_result(result));

        dev_dbg(&dev->core, "%s:%d: %llxh\n", __func__, __LINE__,
                *bytes_waiting);
        return result;
}

/**
 * ps3_vuart_set_interrupt_mask - Enable/disable the port interrupt sources.
 * @dev: The struct ps3_system_bus_device instance.
 * @bmp: Logical OR of enum vuart_interrupt_mask values. A zero bit disables.
 */

static int ps3_vuart_set_interrupt_mask(struct ps3_system_bus_device *dev,
        unsigned long mask)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        dev_dbg(&dev->core, "%s:%d: %lxh\n", __func__, __LINE__, mask);

        priv->interrupt_mask = mask;

        result = lv1_set_virtual_uart_param(dev->port_number,
                PARAM_INTERRUPT_MASK, priv->interrupt_mask);

        if (result)
                dev_dbg(&dev->core, "%s:%d: interrupt_mask failed: %s\n",
                        __func__, __LINE__, ps3_result(result));

        return result;
}

static int ps3_vuart_get_interrupt_status(struct ps3_system_bus_device *dev,
        unsigned long *status)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        u64 tmp;

        result = lv1_get_virtual_uart_param(dev->port_number,
                PARAM_INTERRUPT_STATUS, &tmp);

        if (result)
                dev_dbg(&dev->core, "%s:%d: interrupt_status failed: %s\n",
                        __func__, __LINE__, ps3_result(result));

        *status = tmp & priv->interrupt_mask;

        dev_dbg(&dev->core, "%s:%d: m %llxh, s %llxh, m&s %lxh\n",
                __func__, __LINE__, priv->interrupt_mask, tmp, *status);

        return result;
}

int ps3_vuart_enable_interrupt_tx(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_TX) ? 0
                : ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                | INTERRUPT_MASK_TX);
}

int ps3_vuart_enable_interrupt_rx(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_RX) ? 0
                : ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                | INTERRUPT_MASK_RX);
}

int ps3_vuart_enable_interrupt_disconnect(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_DISCONNECT) ? 0
                : ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                | INTERRUPT_MASK_DISCONNECT);
}

int ps3_vuart_disable_interrupt_tx(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_TX)
                ? ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                & ~INTERRUPT_MASK_TX) : 0;
}

int ps3_vuart_disable_interrupt_rx(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_RX)
                ? ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                & ~INTERRUPT_MASK_RX) : 0;
}

int ps3_vuart_disable_interrupt_disconnect(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        return (priv->interrupt_mask & INTERRUPT_MASK_DISCONNECT)
                ? ps3_vuart_set_interrupt_mask(dev, priv->interrupt_mask
                & ~INTERRUPT_MASK_DISCONNECT) : 0;
}

/**
 * ps3_vuart_raw_write - Low level write helper.
 * @dev: The struct ps3_system_bus_device instance.
 *
 * Do not call ps3_vuart_raw_write directly, use ps3_vuart_write.
 */

static int ps3_vuart_raw_write(struct ps3_system_bus_device *dev,
        const void *buf, unsigned int bytes, u64 *bytes_written)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        result = lv1_write_virtual_uart(dev->port_number,
                ps3_mm_phys_to_lpar(__pa(buf)), bytes, bytes_written);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: lv1_write_virtual_uart failed: "
                        "%s\n", __func__, __LINE__, ps3_result(result));
                return result;
        }

        priv->stats.bytes_written += *bytes_written;

        dev_dbg(&dev->core, "%s:%d: wrote %llxh/%xh=>%lxh\n", __func__, __LINE__,
                *bytes_written, bytes, priv->stats.bytes_written);

        return result;
}

/**
 * ps3_vuart_raw_read - Low level read helper.
 * @dev: The struct ps3_system_bus_device instance.
 *
 * Do not call ps3_vuart_raw_read directly, use ps3_vuart_read.
 */

static int ps3_vuart_raw_read(struct ps3_system_bus_device *dev, void *buf,
        unsigned int bytes, u64 *bytes_read)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);

        dev_dbg(&dev->core, "%s:%d: %xh\n", __func__, __LINE__, bytes);

        result = lv1_read_virtual_uart(dev->port_number,
                ps3_mm_phys_to_lpar(__pa(buf)), bytes, bytes_read);

        if (result) {
                dev_dbg(&dev->core, "%s:%d: lv1_read_virtual_uart failed: %s\n",
                        __func__, __LINE__, ps3_result(result));
                return result;
        }

        priv->stats.bytes_read += *bytes_read;

        dev_dbg(&dev->core, "%s:%d: read %llxh/%xh=>%lxh\n", __func__, __LINE__,
                *bytes_read, bytes, priv->stats.bytes_read);

        return result;
}

/**
 * ps3_vuart_clear_rx_bytes - Discard bytes received.
 * @dev: The struct ps3_system_bus_device instance.
 * @bytes: Max byte count to discard, zero = all pending.
 *
 * Used to clear pending rx interrupt source.  Will not block.
 */

void ps3_vuart_clear_rx_bytes(struct ps3_system_bus_device *dev,
        unsigned int bytes)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        u64 bytes_waiting;
        void *tmp;

        result = ps3_vuart_get_rx_bytes_waiting(dev, &bytes_waiting);

        BUG_ON(result);

        bytes = bytes ? min(bytes, (unsigned int)bytes_waiting) : bytes_waiting;

        dev_dbg(&dev->core, "%s:%d: %u\n", __func__, __LINE__, bytes);

        if (!bytes)
                return;

        /* Add some extra space for recently arrived data. */

        bytes += 128;

        tmp = kmalloc(bytes, GFP_KERNEL);

        if (!tmp)
                return;

        ps3_vuart_raw_read(dev, tmp, bytes, &bytes_waiting);

        kfree(tmp);

        /* Don't include these bytes in the stats. */

        priv->stats.bytes_read -= bytes_waiting;
}
EXPORT_SYMBOL_GPL(ps3_vuart_clear_rx_bytes);

/**
 * struct list_buffer - An element for a port device fifo buffer list.
 */

struct list_buffer {
        struct list_head link;
        const unsigned char *head;
        const unsigned char *tail;
        unsigned long dbg_number;
        unsigned char data[];
};

/**
 * ps3_vuart_write - the entry point for writing data to a port
 * @dev: The struct ps3_system_bus_device instance.
 *
 * If the port is idle on entry as much of the incoming data is written to
 * the port as the port will accept.  Otherwise a list buffer is created
 * and any remaning incoming data is copied to that buffer.  The buffer is
 * then enqueued for transmision via the transmit interrupt.
 */

int ps3_vuart_write(struct ps3_system_bus_device *dev, const void *buf,
        unsigned int bytes)
{
        static unsigned long dbg_number;
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long flags;
        struct list_buffer *lb;

        dev_dbg(&dev->core, "%s:%d: %u(%xh) bytes\n", __func__, __LINE__,
                bytes, bytes);

        spin_lock_irqsave(&priv->tx_list.lock, flags);

        if (list_empty(&priv->tx_list.head)) {
                u64 bytes_written;

                result = ps3_vuart_raw_write(dev, buf, bytes, &bytes_written);

                spin_unlock_irqrestore(&priv->tx_list.lock, flags);

                if (result) {
                        dev_dbg(&dev->core,
                                "%s:%d: ps3_vuart_raw_write failed\n",
                                __func__, __LINE__);
                        return result;
                }

                if (bytes_written == bytes) {
                        dev_dbg(&dev->core, "%s:%d: wrote %xh bytes\n",
                                __func__, __LINE__, bytes);
                        return 0;
                }

                bytes -= bytes_written;
                buf += bytes_written;
        } else
                spin_unlock_irqrestore(&priv->tx_list.lock, flags);

        lb = kmalloc(sizeof(struct list_buffer) + bytes, GFP_KERNEL);

        if (!lb)
                return -ENOMEM;

        memcpy(lb->data, buf, bytes);
        lb->head = lb->data;
        lb->tail = lb->data + bytes;
        lb->dbg_number = ++dbg_number;

        spin_lock_irqsave(&priv->tx_list.lock, flags);
        list_add_tail(&lb->link, &priv->tx_list.head);
        ps3_vuart_enable_interrupt_tx(dev);
        spin_unlock_irqrestore(&priv->tx_list.lock, flags);

        dev_dbg(&dev->core, "%s:%d: queued buf_%lu, %xh bytes\n",
                __func__, __LINE__, lb->dbg_number, bytes);

        return 0;
}
EXPORT_SYMBOL_GPL(ps3_vuart_write);

/**
 * ps3_vuart_queue_rx_bytes - Queue waiting bytes into the buffer list.
 * @dev: The struct ps3_system_bus_device instance.
 * @bytes_queued: Number of bytes queued to the buffer list.
 *
 * Must be called with priv->rx_list.lock held.
 */

static int ps3_vuart_queue_rx_bytes(struct ps3_system_bus_device *dev,
        u64 *bytes_queued)
{
        static unsigned long dbg_number;
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        struct list_buffer *lb;
        u64 bytes;

        *bytes_queued = 0;

        result = ps3_vuart_get_rx_bytes_waiting(dev, &bytes);
        BUG_ON(result);

        if (result)
                return -EIO;

        if (!bytes)
                return 0;

        /* Add some extra space for recently arrived data. */

        bytes += 128;

        lb = kmalloc(sizeof(struct list_buffer) + bytes, GFP_ATOMIC);

        if (!lb)
                return -ENOMEM;

        ps3_vuart_raw_read(dev, lb->data, bytes, &bytes);

        lb->head = lb->data;
        lb->tail = lb->data + bytes;
        lb->dbg_number = ++dbg_number;

        list_add_tail(&lb->link, &priv->rx_list.head);
        priv->rx_list.bytes_held += bytes;

        dev_dbg(&dev->core, "%s:%d: buf_%lu: queued %llxh bytes\n",
                __func__, __LINE__, lb->dbg_number, bytes);

        *bytes_queued = bytes;

        return 0;
}

/**
 * ps3_vuart_read - The entry point for reading data from a port.
 *
 * Queue data waiting at the port, and if enough bytes to satisfy the request
 * are held in the buffer list those bytes are dequeued and copied to the
 * caller's buffer.  Emptied list buffers are retiered.  If the request cannot
 * be statified by bytes held in the list buffers -EAGAIN is returned.
 */

int ps3_vuart_read(struct ps3_system_bus_device *dev, void *buf,
        unsigned int bytes)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long flags;
        struct list_buffer *lb, *n;
        unsigned long bytes_read;

        dev_dbg(&dev->core, "%s:%d: %u(%xh) bytes\n", __func__, __LINE__,
                bytes, bytes);

        spin_lock_irqsave(&priv->rx_list.lock, flags);

        /* Queue rx bytes here for polled reads. */

        while (priv->rx_list.bytes_held < bytes) {
                u64 tmp;

                result = ps3_vuart_queue_rx_bytes(dev, &tmp);
                if (result || !tmp) {
                        dev_dbg(&dev->core, "%s:%d: starved for %lxh bytes\n",
                                __func__, __LINE__,
                                bytes - priv->rx_list.bytes_held);
                        spin_unlock_irqrestore(&priv->rx_list.lock, flags);
                        return -EAGAIN;
                }
        }

        list_for_each_entry_safe(lb, n, &priv->rx_list.head, link) {
                bytes_read = min((unsigned int)(lb->tail - lb->head), bytes);

                memcpy(buf, lb->head, bytes_read);
                buf += bytes_read;
                bytes -= bytes_read;
                priv->rx_list.bytes_held -= bytes_read;

                if (bytes_read < lb->tail - lb->head) {
                        lb->head += bytes_read;
                        dev_dbg(&dev->core, "%s:%d: buf_%lu: dequeued %lxh "
                                "bytes\n", __func__, __LINE__, lb->dbg_number,
                                bytes_read);
                        spin_unlock_irqrestore(&priv->rx_list.lock, flags);
                        return 0;
                }

                dev_dbg(&dev->core, "%s:%d: buf_%lu: free, dequeued %lxh "
                        "bytes\n", __func__, __LINE__, lb->dbg_number,
                        bytes_read);

                list_del(&lb->link);
                kfree(lb);
        }

        spin_unlock_irqrestore(&priv->rx_list.lock, flags);
        return 0;
}
EXPORT_SYMBOL_GPL(ps3_vuart_read);

/**
 * ps3_vuart_work - Asynchronous read handler.
 */

static void ps3_vuart_work(struct work_struct *work)
{
        struct ps3_system_bus_device *dev =
                ps3_vuart_work_to_system_bus_dev(work);
        struct ps3_vuart_port_driver *drv =
                ps3_system_bus_dev_to_vuart_drv(dev);

        BUG_ON(!drv);
        drv->work(dev);
}

int ps3_vuart_read_async(struct ps3_system_bus_device *dev, unsigned int bytes)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long flags;

        if (priv->rx_list.work.trigger) {
                dev_dbg(&dev->core, "%s:%d: warning, multiple calls\n",
                        __func__, __LINE__);
                return -EAGAIN;
        }

        BUG_ON(!bytes);

        PREPARE_WORK(&priv->rx_list.work.work, ps3_vuart_work);

        spin_lock_irqsave(&priv->rx_list.lock, flags);
        if (priv->rx_list.bytes_held >= bytes) {
                dev_dbg(&dev->core, "%s:%d: schedule_work %xh bytes\n",
                        __func__, __LINE__, bytes);
                schedule_work(&priv->rx_list.work.work);
                spin_unlock_irqrestore(&priv->rx_list.lock, flags);
                return 0;
        }

        priv->rx_list.work.trigger = bytes;
        spin_unlock_irqrestore(&priv->rx_list.lock, flags);

        dev_dbg(&dev->core, "%s:%d: waiting for %u(%xh) bytes\n", __func__,
                __LINE__, bytes, bytes);

        return 0;
}
EXPORT_SYMBOL_GPL(ps3_vuart_read_async);

void ps3_vuart_cancel_async(struct ps3_system_bus_device *dev)
{
        to_port_priv(dev)->rx_list.work.trigger = 0;
}
EXPORT_SYMBOL_GPL(ps3_vuart_cancel_async);

/**
 * ps3_vuart_handle_interrupt_tx - third stage transmit interrupt handler
 *
 * Services the transmit interrupt for the port.  Writes as much data from the
 * buffer list as the port will accept.  Retires any emptied list buffers and
 * adjusts the final list buffer state for a partial write.
 */

static int ps3_vuart_handle_interrupt_tx(struct ps3_system_bus_device *dev)
{
        int result = 0;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long flags;
        struct list_buffer *lb, *n;
        unsigned long bytes_total = 0;

        dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);

        spin_lock_irqsave(&priv->tx_list.lock, flags);

        list_for_each_entry_safe(lb, n, &priv->tx_list.head, link) {

                u64 bytes_written;

                result = ps3_vuart_raw_write(dev, lb->head, lb->tail - lb->head,
                        &bytes_written);

                if (result) {
                        dev_dbg(&dev->core,
                                "%s:%d: ps3_vuart_raw_write failed\n",
                                __func__, __LINE__);
                        break;
                }

                bytes_total += bytes_written;

                if (bytes_written < lb->tail - lb->head) {
                        lb->head += bytes_written;
                        dev_dbg(&dev->core,
                                "%s:%d cleared buf_%lu, %llxh bytes\n",
                                __func__, __LINE__, lb->dbg_number,
                                bytes_written);
                        goto port_full;
                }

                dev_dbg(&dev->core, "%s:%d free buf_%lu\n", __func__, __LINE__,
                        lb->dbg_number);

                list_del(&lb->link);
                kfree(lb);
        }

        ps3_vuart_disable_interrupt_tx(dev);
port_full:
        spin_unlock_irqrestore(&priv->tx_list.lock, flags);
        dev_dbg(&dev->core, "%s:%d wrote %lxh bytes total\n",
                __func__, __LINE__, bytes_total);
        return result;
}

/**
 * ps3_vuart_handle_interrupt_rx - third stage receive interrupt handler
 *
 * Services the receive interrupt for the port.  Creates a list buffer and
 * copies all waiting port data to that buffer and enqueues the buffer in the
 * buffer list.  Buffer list data is dequeued via ps3_vuart_read.
 */

static int ps3_vuart_handle_interrupt_rx(struct ps3_system_bus_device *dev)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long flags;
        u64 bytes;

        dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);

        spin_lock_irqsave(&priv->rx_list.lock, flags);
        result = ps3_vuart_queue_rx_bytes(dev, &bytes);

        if (result) {
                spin_unlock_irqrestore(&priv->rx_list.lock, flags);
                return result;
        }

        if (priv->rx_list.work.trigger && priv->rx_list.bytes_held
                >= priv->rx_list.work.trigger) {
                dev_dbg(&dev->core, "%s:%d: schedule_work %lxh bytes\n",
                        __func__, __LINE__, priv->rx_list.work.trigger);
                priv->rx_list.work.trigger = 0;
                schedule_work(&priv->rx_list.work.work);
        }

        spin_unlock_irqrestore(&priv->rx_list.lock, flags);
        return result;
}

static int ps3_vuart_handle_interrupt_disconnect(
        struct ps3_system_bus_device *dev)
{
        dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);
        BUG_ON("no support");
        return -1;
}

/**
 * ps3_vuart_handle_port_interrupt - second stage interrupt handler
 *
 * Services any pending interrupt types for the port.  Passes control to the
 * third stage type specific interrupt handler.  Returns control to the first
 * stage handler after one iteration.
 */

static int ps3_vuart_handle_port_interrupt(struct ps3_system_bus_device *dev)
{
        int result;
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        unsigned long status;

        result = ps3_vuart_get_interrupt_status(dev, &status);

        if (result)
                return result;

        dev_dbg(&dev->core, "%s:%d: status: %lxh\n", __func__, __LINE__,
                status);

        if (status & INTERRUPT_MASK_DISCONNECT) {
                priv->stats.disconnect_interrupts++;
                result = ps3_vuart_handle_interrupt_disconnect(dev);
                if (result)
                        ps3_vuart_disable_interrupt_disconnect(dev);
        }

        if (status & INTERRUPT_MASK_TX) {
                priv->stats.tx_interrupts++;
                result = ps3_vuart_handle_interrupt_tx(dev);
                if (result)
                        ps3_vuart_disable_interrupt_tx(dev);
        }

        if (status & INTERRUPT_MASK_RX) {
                priv->stats.rx_interrupts++;
                result = ps3_vuart_handle_interrupt_rx(dev);
                if (result)
                        ps3_vuart_disable_interrupt_rx(dev);
        }

        return 0;
}

struct vuart_bus_priv {
        struct ports_bmp *bmp;
        unsigned int virq;
        struct mutex probe_mutex;
        int use_count;
        struct ps3_system_bus_device *devices[PORT_COUNT];
} static vuart_bus_priv;

/**
 * ps3_vuart_irq_handler - first stage interrupt handler
 *
 * Loops finding any interrupting port and its associated instance data.
 * Passes control to the second stage port specific interrupt handler.  Loops
 * until all outstanding interrupts are serviced.
 */

static irqreturn_t ps3_vuart_irq_handler(int irq, void *_private)
{
        struct vuart_bus_priv *bus_priv = _private;

        BUG_ON(!bus_priv);

        while (1) {
                unsigned int port;

                dump_ports_bmp(bus_priv->bmp);

                port = (BITS_PER_LONG - 1) - __ilog2(bus_priv->bmp->status);

                if (port == BITS_PER_LONG)
                        break;

                BUG_ON(port >= PORT_COUNT);
                BUG_ON(!bus_priv->devices[port]);

                ps3_vuart_handle_port_interrupt(bus_priv->devices[port]);
        }

        return IRQ_HANDLED;
}

static int ps3_vuart_bus_interrupt_get(void)
{
        int result;

        pr_debug(" -> %s:%d\n", __func__, __LINE__);

        vuart_bus_priv.use_count++;

        BUG_ON(vuart_bus_priv.use_count > 2);

        if (vuart_bus_priv.use_count != 1)
                return 0;

        BUG_ON(vuart_bus_priv.bmp);

        vuart_bus_priv.bmp = kzalloc(sizeof(struct ports_bmp), GFP_KERNEL);

        if (!vuart_bus_priv.bmp) {
                pr_debug("%s:%d: kzalloc failed.\n", __func__, __LINE__);
                result = -ENOMEM;
                goto fail_bmp_malloc;
        }

        result = ps3_vuart_irq_setup(PS3_BINDING_CPU_ANY, vuart_bus_priv.bmp,
                &vuart_bus_priv.virq);

        if (result) {
                pr_debug("%s:%d: ps3_vuart_irq_setup failed (%d)\n",
                        __func__, __LINE__, result);
                result = -EPERM;
                goto fail_alloc_irq;
        }

        result = request_irq(vuart_bus_priv.virq, ps3_vuart_irq_handler,
                IRQF_DISABLED, "vuart", &vuart_bus_priv);

        if (result) {
                pr_debug("%s:%d: request_irq failed (%d)\n",
                        __func__, __LINE__, result);
                goto fail_request_irq;
        }

        pr_debug(" <- %s:%d: ok\n", __func__, __LINE__);
        return result;

fail_request_irq:
        ps3_vuart_irq_destroy(vuart_bus_priv.virq);
        vuart_bus_priv.virq = NO_IRQ;
fail_alloc_irq:
        kfree(vuart_bus_priv.bmp);
        vuart_bus_priv.bmp = NULL;
fail_bmp_malloc:
        vuart_bus_priv.use_count--;
        pr_debug(" <- %s:%d: failed\n", __func__, __LINE__);
        return result;
}

static int ps3_vuart_bus_interrupt_put(void)
{
        pr_debug(" -> %s:%d\n", __func__, __LINE__);

        vuart_bus_priv.use_count--;

        BUG_ON(vuart_bus_priv.use_count < 0);

        if (vuart_bus_priv.use_count != 0)
                return 0;

        free_irq(vuart_bus_priv.virq, &vuart_bus_priv);

        ps3_vuart_irq_destroy(vuart_bus_priv.virq);
        vuart_bus_priv.virq = NO_IRQ;

        kfree(vuart_bus_priv.bmp);
        vuart_bus_priv.bmp = NULL;

        pr_debug(" <- %s:%d\n", __func__, __LINE__);
        return 0;
}

static int ps3_vuart_probe(struct ps3_system_bus_device *dev)
{
        int result;
        struct ps3_vuart_port_driver *drv;
        struct ps3_vuart_port_priv *priv = NULL;

        dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);

        drv = ps3_system_bus_dev_to_vuart_drv(dev);

        dev_dbg(&dev->core, "%s:%d: (%s)\n", __func__, __LINE__,
                drv->core.core.name);

        BUG_ON(!drv);

        if (dev->port_number >= PORT_COUNT) {
                BUG();
                return -EINVAL;
        }

        mutex_lock(&vuart_bus_priv.probe_mutex);

        result = ps3_vuart_bus_interrupt_get();

        if (result)
                goto fail_setup_interrupt;

        if (vuart_bus_priv.devices[dev->port_number]) {
                dev_dbg(&dev->core, "%s:%d: port busy (%d)\n", __func__,
                        __LINE__, dev->port_number);
                result = -EBUSY;
                goto fail_busy;
        }

        vuart_bus_priv.devices[dev->port_number] = dev;

        /* Setup dev->driver_priv. */

        dev->driver_priv = kzalloc(sizeof(struct ps3_vuart_port_priv),
                GFP_KERNEL);

        if (!dev->driver_priv) {
                result = -ENOMEM;
                goto fail_dev_malloc;
        }

        priv = to_port_priv(dev);

        INIT_LIST_HEAD(&priv->tx_list.head);
        spin_lock_init(&priv->tx_list.lock);

        INIT_LIST_HEAD(&priv->rx_list.head);
        spin_lock_init(&priv->rx_list.lock);

        INIT_WORK(&priv->rx_list.work.work, NULL);
        priv->rx_list.work.trigger = 0;
        priv->rx_list.work.dev = dev;

        /* clear stale pending interrupts */

        ps3_vuart_clear_rx_bytes(dev, 0);

        ps3_vuart_set_interrupt_mask(dev, INTERRUPT_MASK_RX);

        ps3_vuart_set_triggers(dev, 1, 1);

        if (drv->probe)
                result = drv->probe(dev);
        else {
                result = 0;
                dev_info(&dev->core, "%s:%d: no probe method\n", __func__,
                        __LINE__);
        }

        if (result) {
                dev_dbg(&dev->core, "%s:%d: drv->probe failed\n",
                        __func__, __LINE__);
                goto fail_probe;
        }

        mutex_unlock(&vuart_bus_priv.probe_mutex);

        return result;

fail_probe:
        ps3_vuart_set_interrupt_mask(dev, 0);
        kfree(dev->driver_priv);
        dev->driver_priv = NULL;
fail_dev_malloc:
        vuart_bus_priv.devices[dev->port_number] = NULL;
fail_busy:
        ps3_vuart_bus_interrupt_put();
fail_setup_interrupt:
        mutex_unlock(&vuart_bus_priv.probe_mutex);
        dev_dbg(&dev->core, "%s:%d: failed\n", __func__, __LINE__);
        return result;
}

/**
 * ps3_vuart_cleanup - common cleanup helper.
 * @dev: The struct ps3_system_bus_device instance.
 *
 * Cleans interrupts and HV resources.  Must be called with
 * vuart_bus_priv.probe_mutex held.  Used by ps3_vuart_remove and
 * ps3_vuart_shutdown.  After this call, polled reading will still work.
 */

static int ps3_vuart_cleanup(struct ps3_system_bus_device *dev)
{
        dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);

        ps3_vuart_cancel_async(dev);
        ps3_vuart_set_interrupt_mask(dev, 0);
        ps3_vuart_bus_interrupt_put();
        return 0;
}

/**
 * ps3_vuart_remove - Completely clean the device instance.
 * @dev: The struct ps3_system_bus_device instance.
 *
 * Cleans all memory, interrupts and HV resources.  After this call the
 * device can no longer be used.
 */

static int ps3_vuart_remove(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_priv *priv = to_port_priv(dev);
        struct ps3_vuart_port_driver *drv;

        BUG_ON(!dev);

        mutex_lock(&vuart_bus_priv.probe_mutex);

        dev_dbg(&dev->core, " -> %s:%d: match_id %d\n", __func__, __LINE__,
                dev->match_id);

        if (!dev->core.driver) {
                dev_dbg(&dev->core, "%s:%d: no driver bound\n", __func__,
                        __LINE__);
                mutex_unlock(&vuart_bus_priv.probe_mutex);
                return 0;
        }

        drv = ps3_system_bus_dev_to_vuart_drv(dev);

        BUG_ON(!drv);

        if (drv->remove) {
                drv->remove(dev);
        } else {
                dev_dbg(&dev->core, "%s:%d: no remove method\n", __func__,
                __LINE__);
                BUG();
        }

        ps3_vuart_cleanup(dev);

        vuart_bus_priv.devices[dev->port_number] = NULL;
        kfree(priv);
        priv = NULL;

        dev_dbg(&dev->core, " <- %s:%d\n", __func__, __LINE__);
        mutex_unlock(&vuart_bus_priv.probe_mutex);
        return 0;
}

/**
 * ps3_vuart_shutdown - Cleans interrupts and HV resources.
 * @dev: The struct ps3_system_bus_device instance.
 *
 * Cleans interrupts and HV resources.  After this call the
 * device can still be used in polling mode.  This behavior required
 * by sys-manager to be able to complete the device power operation
 * sequence.
 */

static int ps3_vuart_shutdown(struct ps3_system_bus_device *dev)
{
        struct ps3_vuart_port_driver *drv;

        BUG_ON(!dev);

        mutex_lock(&vuart_bus_priv.probe_mutex);

        dev_dbg(&dev->core, " -> %s:%d: match_id %d\n", __func__, __LINE__,
                dev->match_id);

        if (!dev->core.driver) {
                dev_dbg(&dev->core, "%s:%d: no driver bound\n", __func__,
                        __LINE__);
                mutex_unlock(&vuart_bus_priv.probe_mutex);
                return 0;
        }

        drv = ps3_system_bus_dev_to_vuart_drv(dev);

        BUG_ON(!drv);

        if (drv->shutdown)
                drv->shutdown(dev);
        else if (drv->remove) {
                dev_dbg(&dev->core, "%s:%d: no shutdown, calling remove\n",
                        __func__, __LINE__);
                drv->remove(dev);
        } else {
                dev_dbg(&dev->core, "%s:%d: no shutdown method\n", __func__,
                        __LINE__);
                BUG();
        }

        ps3_vuart_cleanup(dev);

        dev_dbg(&dev->core, " <- %s:%d\n", __func__, __LINE__);

        mutex_unlock(&vuart_bus_priv.probe_mutex);
        return 0;
}

static int __init ps3_vuart_bus_init(void)
{
        pr_debug("%s:%d:\n", __func__, __LINE__);

        if (!firmware_has_feature(FW_FEATURE_PS3_LV1))
                return -ENODEV;

        mutex_init(&vuart_bus_priv.probe_mutex);

        return 0;
}

static void __exit ps3_vuart_bus_exit(void)
{
        pr_debug("%s:%d:\n", __func__, __LINE__);
}

core_initcall(ps3_vuart_bus_init);
module_exit(ps3_vuart_bus_exit);

/**
 * ps3_vuart_port_driver_register - Add a vuart port device driver.
 */

int ps3_vuart_port_driver_register(struct ps3_vuart_port_driver *drv)
{
        int result;

        pr_debug("%s:%d: (%s)\n", __func__, __LINE__, drv->core.core.name);

        BUG_ON(!drv->core.match_id);
        BUG_ON(!drv->core.core.name);

        drv->core.probe = ps3_vuart_probe;
        drv->core.remove = ps3_vuart_remove;
        drv->core.shutdown = ps3_vuart_shutdown;

        result = ps3_system_bus_driver_register(&drv->core);
        return result;
}
EXPORT_SYMBOL_GPL(ps3_vuart_port_driver_register);

/**
 * ps3_vuart_port_driver_unregister - Remove a vuart port device driver.
 */

void ps3_vuart_port_driver_unregister(struct ps3_vuart_port_driver *drv)
{
        pr_debug("%s:%d: (%s)\n", __func__, __LINE__, drv->core.core.name);
        ps3_system_bus_driver_unregister(&drv->core);
}
EXPORT_SYMBOL_GPL(ps3_vuart_port_driver_unregister);