/*
 *      linux/drivers/net/wireless/libertas/if_spi.c
 *
 *      Driver for Marvell SPI WLAN cards.
 *
 *      Copyright 2008 Analog Devices Inc.
 *
 *      Authors:
 *      Andrey Yurovsky <andrey@cozybit.com>
 *      Colin McCabe <colin@cozybit.com>
 *
 *      Inspired by if_sdio.c, Copyright 2007-2008 Pierre Ossman
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/hardirq.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/firmware.h>
#include <linux/jiffies.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/spi/libertas_spi.h>
#include <linux/spi/spi.h>

#include "host.h"
#include "decl.h"
#include "defs.h"
#include "dev.h"
#include "if_spi.h"

struct if_spi_packet {
        struct list_head                list;
        u16                             blen;
        u8                              buffer[0] __attribute__((aligned(4)));
};

struct if_spi_card {
        struct spi_device               *spi;
        struct lbs_private              *priv;
        struct libertas_spi_platform_data *pdata;

        /* The card ID and card revision, as reported by the hardware. */
        u16                             card_id;
        u8                              card_rev;

        /* The last time that we initiated an SPU operation */
        unsigned long                   prev_xfer_time;

        int                             use_dummy_writes;
        unsigned long                   spu_port_delay;
        unsigned long                   spu_reg_delay;

        /* Handles all SPI communication (except for FW load) */
        struct workqueue_struct         *workqueue;
        struct work_struct              packet_work;
        struct work_struct              resume_work;

        u8                              cmd_buffer[IF_SPI_CMD_BUF_SIZE];

        /* A buffer of incoming packets from libertas core.
         * Since we can't sleep in hw_host_to_card, we have to buffer
         * them. */
        struct list_head                cmd_packet_list;
        struct list_head                data_packet_list;

        /* Protects cmd_packet_list and data_packet_list */
        spinlock_t                      buffer_lock;

        /* True is card suspended */
        u8                              suspended;
};

static void free_if_spi_card(struct if_spi_card *card)
{
        struct list_head *cursor, *next;
        struct if_spi_packet *packet;

        list_for_each_safe(cursor, next, &card->cmd_packet_list) {
                packet = container_of(cursor, struct if_spi_packet, list);
                list_del(&packet->list);
                kfree(packet);
        }
        list_for_each_safe(cursor, next, &card->data_packet_list) {
                packet = container_of(cursor, struct if_spi_packet, list);
                list_del(&packet->list);
                kfree(packet);
        }
        spi_set_drvdata(card->spi, NULL);
        kfree(card);
}

#define MODEL_8385      0x04
#define MODEL_8686      0x0b
#define MODEL_8688      0x10

static const struct lbs_fw_table fw_table[] = {
        { MODEL_8385, "libertas/gspi8385_helper.bin", "libertas/gspi8385.bin" },
        { MODEL_8385, "libertas/gspi8385_hlp.bin", "libertas/gspi8385.bin" },
        { MODEL_8686, "libertas/gspi8686_v9_helper.bin", "libertas/gspi8686_v9.bin" },
        { MODEL_8686, "libertas/gspi8686_hlp.bin", "libertas/gspi8686.bin" },
        { MODEL_8688, "libertas/gspi8688_helper.bin", "libertas/gspi8688.bin" },
        { 0, NULL, NULL }
};
MODULE_FIRMWARE("libertas/gspi8385_helper.bin");
MODULE_FIRMWARE("libertas/gspi8385_hlp.bin");
MODULE_FIRMWARE("libertas/gspi8385.bin");
MODULE_FIRMWARE("libertas/gspi8686_v9_helper.bin");
MODULE_FIRMWARE("libertas/gspi8686_v9.bin");
MODULE_FIRMWARE("libertas/gspi8686_hlp.bin");
MODULE_FIRMWARE("libertas/gspi8686.bin");
MODULE_FIRMWARE("libertas/gspi8688_helper.bin");
MODULE_FIRMWARE("libertas/gspi8688.bin");


/*
 * SPI Interface Unit Routines
 *
 * The SPU sits between the host and the WLAN module.
 * All communication with the firmware is through SPU transactions.
 *
 * First we have to put a SPU register name on the bus. Then we can
 * either read from or write to that register.
 *
 */

static void spu_transaction_init(struct if_spi_card *card)
{
        if (!time_after(jiffies, card->prev_xfer_time + 1)) {
                /* Unfortunately, the SPU requires a delay between successive
                 * transactions. If our last transaction was more than a jiffy
                 * ago, we have obviously already delayed enough.
                 * If not, we have to busy-wait to be on the safe side. */
                ndelay(400);
        }
}

static void spu_transaction_finish(struct if_spi_card *card)
{
        card->prev_xfer_time = jiffies;
}

/*
 * Write out a byte buffer to an SPI register,
 * using a series of 16-bit transfers.
 */
static int spu_write(struct if_spi_card *card, u16 reg, const u8 *buf, int len)
{
        int err = 0;
        __le16 reg_out = cpu_to_le16(reg | IF_SPI_WRITE_OPERATION_MASK);
        struct spi_message m;
        struct spi_transfer reg_trans;
        struct spi_transfer data_trans;

        spi_message_init(&m);
        memset(&reg_trans, 0, sizeof(reg_trans));
        memset(&data_trans, 0, sizeof(data_trans));

        /* You must give an even number of bytes to the SPU, even if it
         * doesn't care about the last one.  */
        BUG_ON(len & 0x1);

        spu_transaction_init(card);

        /* write SPU register index */
        reg_trans.tx_buf = &reg_out;
        reg_trans.len = sizeof(reg_out);

        data_trans.tx_buf = buf;
        data_trans.len = len;

        spi_message_add_tail(&reg_trans, &m);
        spi_message_add_tail(&data_trans, &m);

        err = spi_sync(card->spi, &m);
        spu_transaction_finish(card);
        return err;
}

static inline int spu_write_u16(struct if_spi_card *card, u16 reg, u16 val)
{
        __le16 buff;

        buff = cpu_to_le16(val);
        return spu_write(card, reg, (u8 *)&buff, sizeof(u16));
}

static inline int spu_reg_is_port_reg(u16 reg)
{
        switch (reg) {
        case IF_SPI_IO_RDWRPORT_REG:
        case IF_SPI_CMD_RDWRPORT_REG:
        case IF_SPI_DATA_RDWRPORT_REG:
                return 1;
        default:
                return 0;
        }
}

static int spu_read(struct if_spi_card *card, u16 reg, u8 *buf, int len)
{
        unsigned int delay;
        int err = 0;
        __le16 reg_out = cpu_to_le16(reg | IF_SPI_READ_OPERATION_MASK);
        struct spi_message m;
        struct spi_transfer reg_trans;
        struct spi_transfer dummy_trans;
        struct spi_transfer data_trans;

        /*
         * You must take an even number of bytes from the SPU, even if you
         * don't care about the last one.
         */
        BUG_ON(len & 0x1);

        spu_transaction_init(card);

        spi_message_init(&m);
        memset(&reg_trans, 0, sizeof(reg_trans));
        memset(&dummy_trans, 0, sizeof(dummy_trans));
        memset(&data_trans, 0, sizeof(data_trans));

        /* write SPU register index */
        reg_trans.tx_buf = &reg_out;
        reg_trans.len = sizeof(reg_out);
        spi_message_add_tail(&reg_trans, &m);

        delay = spu_reg_is_port_reg(reg) ? card->spu_port_delay :
                                                card->spu_reg_delay;
        if (card->use_dummy_writes) {
                /* Clock in dummy cycles while the SPU fills the FIFO */
                dummy_trans.len = delay / 8;
                spi_message_add_tail(&dummy_trans, &m);
        } else {
                /* Busy-wait while the SPU fills the FIFO */
                reg_trans.delay_usecs =
                        DIV_ROUND_UP((100 + (delay * 10)), 1000);
        }

        /* read in data */
        data_trans.rx_buf = buf;
        data_trans.len = len;
        spi_message_add_tail(&data_trans, &m);

        err = spi_sync(card->spi, &m);
        spu_transaction_finish(card);
        return err;
}

/* Read 16 bits from an SPI register */
static inline int spu_read_u16(struct if_spi_card *card, u16 reg, u16 *val)
{
        __le16 buf;
        int ret;

        ret = spu_read(card, reg, (u8 *)&buf, sizeof(buf));
        if (ret == 0)
                *val = le16_to_cpup(&buf);
        return ret;
}

/*
 * Read 32 bits from an SPI register.
 * The low 16 bits are read first.
 */
static int spu_read_u32(struct if_spi_card *card, u16 reg, u32 *val)
{
        __le32 buf;
        int err;

        err = spu_read(card, reg, (u8 *)&buf, sizeof(buf));
        if (!err)
                *val = le32_to_cpup(&buf);
        return err;
}

/*
 * Keep reading 16 bits from an SPI register until you get the correct result.
 *
 * If mask = 0, the correct result is any non-zero number.
 * If mask != 0, the correct result is any number where
 * number & target_mask == target
 *
 * Returns -ETIMEDOUT if a second passes without the correct result.
 */
static int spu_wait_for_u16(struct if_spi_card *card, u16 reg,
                        u16 target_mask, u16 target)
{
        int err;
        unsigned long timeout = jiffies + 5*HZ;
        while (1) {
                u16 val;
                err = spu_read_u16(card, reg, &val);
                if (err)
                        return err;
                if (target_mask) {
                        if ((val & target_mask) == target)
                                return 0;
                } else {
                        if (val)
                                return 0;
                }
                udelay(100);
                if (time_after(jiffies, timeout)) {
                        pr_err("%s: timeout with val=%02x, target_mask=%02x, target=%02x\n",
                               __func__, val, target_mask, target);
                        return -ETIMEDOUT;
                }
        }
}

/*
 * Read 16 bits from an SPI register until you receive a specific value.
 * Returns -ETIMEDOUT if a 4 tries pass without success.
 */
static int spu_wait_for_u32(struct if_spi_card *card, u32 reg, u32 target)
{
        int err, try;
        for (try = 0; try < 4; ++try) {
                u32 val = 0;
                err = spu_read_u32(card, reg, &val);
                if (err)
                        return err;
                if (val == target)
                        return 0;
                mdelay(100);
        }
        return -ETIMEDOUT;
}

static int spu_set_interrupt_mode(struct if_spi_card *card,
                           int suppress_host_int,
                           int auto_int)
{
        int err = 0;

        /*
         * We can suppress a host interrupt by clearing the appropriate
         * bit in the "host interrupt status mask" register
         */
        if (suppress_host_int) {
                err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG, 0);
                if (err)
                        return err;
        } else {
                err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG,
                              IF_SPI_HISM_TX_DOWNLOAD_RDY |
                              IF_SPI_HISM_RX_UPLOAD_RDY |
                              IF_SPI_HISM_CMD_DOWNLOAD_RDY |
                              IF_SPI_HISM_CARDEVENT |
                              IF_SPI_HISM_CMD_UPLOAD_RDY);
                if (err)
                        return err;
        }

        /*
         * If auto-interrupts are on, the completion of certain transactions
         * will trigger an interrupt automatically. If auto-interrupts
         * are off, we need to set the "Card Interrupt Cause" register to
         * trigger a card interrupt.
         */
        if (auto_int) {
                err = spu_write_u16(card, IF_SPI_HOST_INT_CTRL_REG,
                                IF_SPI_HICT_TX_DOWNLOAD_OVER_AUTO |
                                IF_SPI_HICT_RX_UPLOAD_OVER_AUTO |
                                IF_SPI_HICT_CMD_DOWNLOAD_OVER_AUTO |
                                IF_SPI_HICT_CMD_UPLOAD_OVER_AUTO);
                if (err)
                        return err;
        } else {
                err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG, 0);
                if (err)
                        return err;
        }
        return err;
}

static int spu_get_chip_revision(struct if_spi_card *card,
                                  u16 *card_id, u8 *card_rev)
{
        int err = 0;
        u32 dev_ctrl;
        err = spu_read_u32(card, IF_SPI_DEVICEID_CTRL_REG, &dev_ctrl);
        if (err)
                return err;
        *card_id = IF_SPI_DEVICEID_CTRL_REG_TO_CARD_ID(dev_ctrl);
        *card_rev = IF_SPI_DEVICEID_CTRL_REG_TO_CARD_REV(dev_ctrl);
        return err;
}

static int spu_set_bus_mode(struct if_spi_card *card, u16 mode)
{
        int err = 0;
        u16 rval;
        /* set bus mode */
        err = spu_write_u16(card, IF_SPI_SPU_BUS_MODE_REG, mode);
        if (err)
                return err;
        /* Check that we were able to read back what we just wrote. */
        err = spu_read_u16(card, IF_SPI_SPU_BUS_MODE_REG, &rval);
        if (err)
                return err;
        if ((rval & 0xF) != mode) {
                pr_err("Can't read bus mode register\n");
                return -EIO;
        }
        return 0;
}

static int spu_init(struct if_spi_card *card, int use_dummy_writes)
{
        int err = 0;
        u32 delay;

        /*
         * We have to start up in timed delay mode so that we can safely
         * read the Delay Read Register.
         */
        card->use_dummy_writes = 0;
        err = spu_set_bus_mode(card,
                                IF_SPI_BUS_MODE_SPI_CLOCK_PHASE_RISING |
                                IF_SPI_BUS_MODE_DELAY_METHOD_TIMED |
                                IF_SPI_BUS_MODE_16_BIT_ADDRESS_16_BIT_DATA);
        if (err)
                return err;
        card->spu_port_delay = 1000;
        card->spu_reg_delay = 1000;
        err = spu_read_u32(card, IF_SPI_DELAY_READ_REG, &delay);
        if (err)
                return err;
        card->spu_port_delay = delay & 0x0000ffff;
        card->spu_reg_delay = (delay & 0xffff0000) >> 16;

        /* If dummy clock delay mode has been requested, switch to it now */
        if (use_dummy_writes) {
                card->use_dummy_writes = 1;
                err = spu_set_bus_mode(card,
                                IF_SPI_BUS_MODE_SPI_CLOCK_PHASE_RISING |
                                IF_SPI_BUS_MODE_DELAY_METHOD_DUMMY_CLOCK |
                                IF_SPI_BUS_MODE_16_BIT_ADDRESS_16_BIT_DATA);
                if (err)
                        return err;
        }

        lbs_deb_spi("Initialized SPU unit. "
                    "spu_port_delay=0x%04lx, spu_reg_delay=0x%04lx\n",
                    card->spu_port_delay, card->spu_reg_delay);
        return err;
}

/*
 * Firmware Loading
 */

static int if_spi_prog_helper_firmware(struct if_spi_card *card,
                                        const struct firmware *firmware)
{
        int err = 0;
        int bytes_remaining;
        const u8 *fw;
        u8 temp[HELPER_FW_LOAD_CHUNK_SZ];

        lbs_deb_enter(LBS_DEB_SPI);

        err = spu_set_interrupt_mode(card, 1, 0);
        if (err)
                goto out;

        bytes_remaining = firmware->size;
        fw = firmware->data;

        /* Load helper firmware image */
        while (bytes_remaining > 0) {
                /*
                 * Scratch pad 1 should contain the number of bytes we
                 * want to download to the firmware
                 */
                err = spu_write_u16(card, IF_SPI_SCRATCH_1_REG,
                                        HELPER_FW_LOAD_CHUNK_SZ);
                if (err)
                        goto out;

                err = spu_wait_for_u16(card, IF_SPI_HOST_INT_STATUS_REG,
                                        IF_SPI_HIST_CMD_DOWNLOAD_RDY,
                                        IF_SPI_HIST_CMD_DOWNLOAD_RDY);
                if (err)
                        goto out;

                /*
                 * Feed the data into the command read/write port reg
                 * in chunks of 64 bytes
                 */
                memset(temp, 0, sizeof(temp));
                memcpy(temp, fw,
                       min(bytes_remaining, HELPER_FW_LOAD_CHUNK_SZ));
                mdelay(10);
                err = spu_write(card, IF_SPI_CMD_RDWRPORT_REG,
                                        temp, HELPER_FW_LOAD_CHUNK_SZ);
                if (err)
                        goto out;

                /* Interrupt the boot code */
                err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
                if (err)
                        goto out;
                err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG,
                                       IF_SPI_CIC_CMD_DOWNLOAD_OVER);
                if (err)
                        goto out;
                bytes_remaining -= HELPER_FW_LOAD_CHUNK_SZ;
                fw += HELPER_FW_LOAD_CHUNK_SZ;
        }

        /*
         * Once the helper / single stage firmware download is complete,
         * write 0 to scratch pad 1 and interrupt the
         * bootloader. This completes the helper download.
         */
        err = spu_write_u16(card, IF_SPI_SCRATCH_1_REG, FIRMWARE_DNLD_OK);
        if (err)
                goto out;
        err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
        if (err)
                goto out;
        err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG,
                                IF_SPI_CIC_CMD_DOWNLOAD_OVER);
out:
        if (err)
                pr_err("failed to load helper firmware (err=%d)\n", err);
        lbs_deb_leave_args(LBS_DEB_SPI, "err %d", err);
        return err;
}

/*
 * Returns the length of the next packet the firmware expects us to send.
 * Sets crc_err if the previous transfer had a CRC error.
 */
static int if_spi_prog_main_firmware_check_len(struct if_spi_card *card,
                                                int *crc_err)
{
        u16 len;
        int err = 0;

        /*
         * wait until the host interrupt status register indicates
         * that we are ready to download
         */
        err = spu_wait_for_u16(card, IF_SPI_HOST_INT_STATUS_REG,
                                IF_SPI_HIST_CMD_DOWNLOAD_RDY,
                                IF_SPI_HIST_CMD_DOWNLOAD_RDY);
        if (err) {
                pr_err("timed out waiting for host_int_status\n");
                return err;
        }

        /* Ask the device how many bytes of firmware it wants. */
        err = spu_read_u16(card, IF_SPI_SCRATCH_1_REG, &len);
        if (err)
                return err;

        if (len > IF_SPI_CMD_BUF_SIZE) {
                pr_err("firmware load device requested a larger transfer than we are prepared to handle (len = %d)\n",
                       len);
                return -EIO;
        }
        if (len & 0x1) {
                lbs_deb_spi("%s: crc error\n", __func__);
                len &= ~0x1;
                *crc_err = 1;
        } else
                *crc_err = 0;

        return len;
}

static int if_spi_prog_main_firmware(struct if_spi_card *card,
                                        const struct firmware *firmware)
{
        struct lbs_private *priv = card->priv;
        int len, prev_len;
        int bytes, crc_err = 0, err = 0;
        const u8 *fw;
        u16 num_crc_errs;

        lbs_deb_enter(LBS_DEB_SPI);

        err = spu_set_interrupt_mode(card, 1, 0);
        if (err)
                goto out;

        err = spu_wait_for_u16(card, IF_SPI_SCRATCH_1_REG, 0, 0);
        if (err) {
                netdev_err(priv->dev,
                           "%s: timed out waiting for initial scratch reg = 0\n",
                           __func__);
                goto out;
        }

        num_crc_errs = 0;
        prev_len = 0;
        bytes = firmware->size;
        fw = firmware->data;
        while ((len = if_spi_prog_main_firmware_check_len(card, &crc_err))) {
                if (len < 0) {
                        err = len;
                        goto out;
                }
                if (bytes < 0) {
                        /*
                         * If there are no more bytes left, we would normally
                         * expect to have terminated with len = 0
                         */
                        netdev_err(priv->dev,
                                   "Firmware load wants more bytes than we have to offer.\n");
                        break;
                }
                if (crc_err) {
                        /* Previous transfer failed. */
                        if (++num_crc_errs > MAX_MAIN_FW_LOAD_CRC_ERR) {
                                pr_err("Too many CRC errors encountered in firmware load.\n");
                                err = -EIO;
                                goto out;
                        }
                } else {
                        /* Previous transfer succeeded. Advance counters. */
                        bytes -= prev_len;
                        fw += prev_len;
                }
                if (bytes < len) {
                        memset(card->cmd_buffer, 0, len);
                        memcpy(card->cmd_buffer, fw, bytes);
                } else
                        memcpy(card->cmd_buffer, fw, len);

                err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
                if (err)
                        goto out;
                err = spu_write(card, IF_SPI_CMD_RDWRPORT_REG,
                                card->cmd_buffer, len);
                if (err)
                        goto out;
                err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG ,
                                        IF_SPI_CIC_CMD_DOWNLOAD_OVER);
                if (err)
                        goto out;
                prev_len = len;
        }
        if (bytes > prev_len) {
                pr_err("firmware load wants fewer bytes than we have to offer\n");
        }

        /* Confirm firmware download */
        err = spu_wait_for_u32(card, IF_SPI_SCRATCH_4_REG,
                                        SUCCESSFUL_FW_DOWNLOAD_MAGIC);
        if (err) {
                pr_err("failed to confirm the firmware download\n");
                goto out;
        }

out:
        if (err)
                pr_err("failed to load firmware (err=%d)\n", err);
        lbs_deb_leave_args(LBS_DEB_SPI, "err %d", err);
        return err;
}

/*
 * SPI Transfer Thread
 *
 * The SPI worker handles all SPI transfers, so there is no need for a lock.
 */

/* Move a command from the card to the host */
static int if_spi_c2h_cmd(struct if_spi_card *card)
{
        struct lbs_private *priv = card->priv;
        unsigned long flags;
        int err = 0;
        u16 len;
        u8 i;

        /*
         * We need a buffer big enough to handle whatever people send to
         * hw_host_to_card
         */
        BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE < LBS_CMD_BUFFER_SIZE);
        BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE < LBS_UPLD_SIZE);

        /*
         * It's just annoying if the buffer size isn't a multiple of 4, because
         * then we might have len < IF_SPI_CMD_BUF_SIZE but
         * ALIGN(len, 4) > IF_SPI_CMD_BUF_SIZE
         */
        BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE % 4 != 0);

        lbs_deb_enter(LBS_DEB_SPI);

        /* How many bytes are there to read? */
        err = spu_read_u16(card, IF_SPI_SCRATCH_2_REG, &len);
        if (err)
                goto out;
        if (!len) {
                netdev_err(priv->dev, "%s: error: card has no data for host\n",
                           __func__);
                err = -EINVAL;
                goto out;
        } else if (len > IF_SPI_CMD_BUF_SIZE) {
                netdev_err(priv->dev,
                           "%s: error: response packet too large: %d bytes, but maximum is %d\n",
                           __func__, len, IF_SPI_CMD_BUF_SIZE);
                err = -EINVAL;
                goto out;
        }

        /* Read the data from the WLAN module into our command buffer */
        err = spu_read(card, IF_SPI_CMD_RDWRPORT_REG,
                                card->cmd_buffer, ALIGN(len, 4));
        if (err)
                goto out;

        spin_lock_irqsave(&priv->driver_lock, flags);
        i = (priv->resp_idx == 0) ? 1 : 0;
        BUG_ON(priv->resp_len[i]);
        priv->resp_len[i] = len;
        memcpy(priv->resp_buf[i], card->cmd_buffer, len);
        lbs_notify_command_response(priv, i);
        spin_unlock_irqrestore(&priv->driver_lock, flags);

out:
        if (err)
                netdev_err(priv->dev, "%s: err=%d\n", __func__, err);
        lbs_deb_leave(LBS_DEB_SPI);
        return err;
}

/* Move data from the card to the host */
static int if_spi_c2h_data(struct if_spi_card *card)
{
        struct lbs_private *priv = card->priv;
        struct sk_buff *skb;
        char *data;
        u16 len;
        int err = 0;

        lbs_deb_enter(LBS_DEB_SPI);

        /* How many bytes are there to read? */
        err = spu_read_u16(card, IF_SPI_SCRATCH_1_REG, &len);
        if (err)
                goto out;
        if (!len) {
                netdev_err(priv->dev, "%s: error: card has no data for host\n",
                           __func__);
                err = -EINVAL;
                goto out;
        } else if (len > MRVDRV_ETH_RX_PACKET_BUFFER_SIZE) {
                netdev_err(priv->dev,
                           "%s: error: card has %d bytes of data, but our maximum skb size is %zu\n",
                           __func__, len, MRVDRV_ETH_RX_PACKET_BUFFER_SIZE);
                err = -EINVAL;
                goto out;
        }

        /* TODO: should we allocate a smaller skb if we have less data? */
        skb = dev_alloc_skb(MRVDRV_ETH_RX_PACKET_BUFFER_SIZE);
        if (!skb) {
                err = -ENOBUFS;
                goto out;
        }
        skb_reserve(skb, IPFIELD_ALIGN_OFFSET);
        data = skb_put(skb, len);

        /* Read the data from the WLAN module into our skb... */
        err = spu_read(card, IF_SPI_DATA_RDWRPORT_REG, data, ALIGN(len, 4));
        if (err)
                goto free_skb;

        /* pass the SKB to libertas */
        err = lbs_process_rxed_packet(card->priv, skb);
        if (err)
                goto free_skb;

        /* success */
        goto out;

free_skb:
        dev_kfree_skb(skb);
out:
        if (err)
                netdev_err(priv->dev, "%s: err=%d\n", __func__, err);
        lbs_deb_leave(LBS_DEB_SPI);
        return err;
}

/* Move data or a command from the host to the card. */
static void if_spi_h2c(struct if_spi_card *card,
                        struct if_spi_packet *packet, int type)
{
        struct lbs_private *priv = card->priv;
        int err = 0;
        u16 int_type, port_reg;

        switch (type) {
        case MVMS_DAT:
                int_type = IF_SPI_CIC_TX_DOWNLOAD_OVER;
                port_reg = IF_SPI_DATA_RDWRPORT_REG;
                break;
        case MVMS_CMD:
                int_type = IF_SPI_CIC_CMD_DOWNLOAD_OVER;
                port_reg = IF_SPI_CMD_RDWRPORT_REG;
                break;
        default:
                netdev_err(priv->dev, "can't transfer buffer of type %d\n",
                           type);
                err = -EINVAL;
                goto out;
        }

        /* Write the data to the card */
        err = spu_write(card, port_reg, packet->buffer, packet->blen);
        if (err)
                goto out;

out:
        kfree(packet);

        if (err)
                netdev_err(priv->dev, "%s: error %d\n", __func__, err);
}

/* Inform the host about a card event */
static void if_spi_e2h(struct if_spi_card *card)
{
        int err = 0;
        u32 cause;
        struct lbs_private *priv = card->priv;

        err = spu_read_u32(card, IF_SPI_SCRATCH_3_REG, &cause);
        if (err)
                goto out;

        /* re-enable the card event interrupt */
        spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG,
                        ~IF_SPI_HICU_CARD_EVENT);

        /* generate a card interrupt */
        spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG, IF_SPI_CIC_HOST_EVENT);

        lbs_queue_event(priv, cause & 0xff);
out:
        if (err)
                netdev_err(priv->dev, "%s: error %d\n", __func__, err);
}

static void if_spi_host_to_card_worker(struct work_struct *work)
{
        int err;
        struct if_spi_card *card;
        u16 hiStatus;
        unsigned long flags;
        struct if_spi_packet *packet;
        struct lbs_private *priv;

        card = container_of(work, struct if_spi_card, packet_work);
        priv = card->priv;

        lbs_deb_enter(LBS_DEB_SPI);

        /*
         * Read the host interrupt status register to see what we
         * can do.
         */
        err = spu_read_u16(card, IF_SPI_HOST_INT_STATUS_REG,
                                &hiStatus);
        if (err) {
                netdev_err(priv->dev, "I/O error\n");
                goto err;
        }

        if (hiStatus & IF_SPI_HIST_CMD_UPLOAD_RDY) {
                err = if_spi_c2h_cmd(card);
                if (err)
                        goto err;
        }
        if (hiStatus & IF_SPI_HIST_RX_UPLOAD_RDY) {
                err = if_spi_c2h_data(card);
                if (err)
                        goto err;
        }

        /*
         * workaround: in PS mode, the card does not set the Command
         * Download Ready bit, but it sets TX Download Ready.
         */
        if (hiStatus & IF_SPI_HIST_CMD_DOWNLOAD_RDY ||
           (card->priv->psstate != PS_STATE_FULL_POWER &&
            (hiStatus & IF_SPI_HIST_TX_DOWNLOAD_RDY))) {
                /*
                 * This means two things. First of all,
                 * if there was a previous command sent, the card has
                 * successfully received it.
                 * Secondly, it is now ready to download another
                 * command.
                 */
                lbs_host_to_card_done(card->priv);

                /* Do we have any command packets from the host to send? */
                packet = NULL;
                spin_lock_irqsave(&card->buffer_lock, flags);
                if (!list_empty(&card->cmd_packet_list)) {
                        packet = (struct if_spi_packet *)(card->
                                        cmd_packet_list.next);
                        list_del(&packet->list);
                }
                spin_unlock_irqrestore(&card->buffer_lock, flags);

                if (packet)
                        if_spi_h2c(card, packet, MVMS_CMD);
        }
        if (hiStatus & IF_SPI_HIST_TX_DOWNLOAD_RDY) {
                /* Do we have any data packets from the host to send? */
                packet = NULL;
                spin_lock_irqsave(&card->buffer_lock, flags);
                if (!list_empty(&card->data_packet_list)) {
                        packet = (struct if_spi_packet *)(card->
                                        data_packet_list.next);
                        list_del(&packet->list);
                }
                spin_unlock_irqrestore(&card->buffer_lock, flags);

                if (packet)
                        if_spi_h2c(card, packet, MVMS_DAT);
        }
        if (hiStatus & IF_SPI_HIST_CARD_EVENT)
                if_spi_e2h(card);

err:
        if (err)
                netdev_err(priv->dev, "%s: got error %d\n", __func__, err);

        lbs_deb_leave(LBS_DEB_SPI);
}

/*
 * Host to Card
 *
 * Called from Libertas to transfer some data to the WLAN device
 * We can't sleep here.
 */
static int if_spi_host_to_card(struct lbs_private *priv,
                                u8 type, u8 *buf, u16 nb)
{
        int err = 0;
        unsigned long flags;
        struct if_spi_card *card = priv->card;
        struct if_spi_packet *packet;
        u16 blen;

        lbs_deb_enter_args(LBS_DEB_SPI, "type %d, bytes %d", type, nb);

        if (nb == 0) {
                netdev_err(priv->dev, "%s: invalid size requested: %d\n",
                           __func__, nb);
                err = -EINVAL;
                goto out;
        }
        blen = ALIGN(nb, 4);
        packet = kzalloc(sizeof(struct if_spi_packet) + blen, GFP_ATOMIC);
        if (!packet) {
                err = -ENOMEM;
                goto out;
        }
        packet->blen = blen;
        memcpy(packet->buffer, buf, nb);
        memset(packet->buffer + nb, 0, blen - nb);

        switch (type) {
        case MVMS_CMD:
                priv->dnld_sent = DNLD_CMD_SENT;
                spin_lock_irqsave(&card->buffer_lock, flags);
                list_add_tail(&packet->list, &card->cmd_packet_list);
                spin_unlock_irqrestore(&card->buffer_lock, flags);
                break;
        case MVMS_DAT:
                priv->dnld_sent = DNLD_DATA_SENT;
                spin_lock_irqsave(&card->buffer_lock, flags);
                list_add_tail(&packet->list, &card->data_packet_list);
                spin_unlock_irqrestore(&card->buffer_lock, flags);
                break;
        default:
                kfree(packet);
                netdev_err(priv->dev, "can't transfer buffer of type %d\n",
                           type);

                err = -EINVAL;
                break;
        }

        /* Queue spi xfer work */
        queue_work(card->workqueue, &card->packet_work);
out:
        lbs_deb_leave_args(LBS_DEB_SPI, "err=%d", err);
        return err;
}

/*
 * Host Interrupts
 *
 * Service incoming interrupts from the WLAN device. We can't sleep here, so
 * don't try to talk on the SPI bus, just queue the SPI xfer work.
 */
static irqreturn_t if_spi_host_interrupt(int irq, void *dev_id)
{
        struct if_spi_card *card = dev_id;

        queue_work(card->workqueue, &card->packet_work);

        return IRQ_HANDLED;
}

/*
 * SPI callbacks
 */

static int if_spi_init_card(struct if_spi_card *card)
{
        struct lbs_private *priv = card->priv;
        int err, i;
        u32 scratch;
        const struct firmware *helper = NULL;
        const struct firmware *mainfw = NULL;

        lbs_deb_enter(LBS_DEB_SPI);

        err = spu_init(card, card->pdata->use_dummy_writes);
        if (err)
                goto out;
        err = spu_get_chip_revision(card, &card->card_id, &card->card_rev);
        if (err)
                goto out;

        err = spu_read_u32(card, IF_SPI_SCRATCH_4_REG, &scratch);
        if (err)
                goto out;
        if (scratch == SUCCESSFUL_FW_DOWNLOAD_MAGIC)
                lbs_deb_spi("Firmware is already loaded for "
                            "Marvell WLAN 802.11 adapter\n");
        else {
                /* Check if we support this card */
                for (i = 0; i < ARRAY_SIZE(fw_table); i++) {
                        if (card->card_id == fw_table[i].model)
                                break;
                }
                if (i == ARRAY_SIZE(fw_table)) {
                        netdev_err(priv->dev, "Unsupported chip_id: 0x%02x\n",
                                   card->card_id);
                        err = -ENODEV;
                        goto out;
                }

                err = lbs_get_firmware(&card->spi->dev, card->card_id,
                                        &fw_table[0], &helper, &mainfw);
                if (err) {
                        netdev_err(priv->dev, "failed to find firmware (%d)\n",
                                   err);
                        goto out;
                }

                lbs_deb_spi("Initializing FW for Marvell WLAN 802.11 adapter "
                                "(chip_id = 0x%04x, chip_rev = 0x%02x) "
                                "attached to SPI bus_num %d, chip_select %d. "
                                "spi->max_speed_hz=%d\n",
                                card->card_id, card->card_rev,
                                card->spi->master->bus_num,
                                card->spi->chip_select,
                                card->spi->max_speed_hz);
                err = if_spi_prog_helper_firmware(card, helper);
                if (err)
                        goto out;
                err = if_spi_prog_main_firmware(card, mainfw);
                if (err)
                        goto out;
                lbs_deb_spi("loaded FW for Marvell WLAN 802.11 adapter\n");
        }

        err = spu_set_interrupt_mode(card, 0, 1);
        if (err)
                goto out;

out:
        release_firmware(helper);
        release_firmware(mainfw);

        lbs_deb_leave_args(LBS_DEB_SPI, "err %d\n", err);

        return err;
}

static void if_spi_resume_worker(struct work_struct *work)
{
        struct if_spi_card *card;

        card = container_of(work, struct if_spi_card, resume_work);

        if (card->suspended) {
                if (card->pdata->setup)
                        card->pdata->setup(card->spi);

                /* Init card ... */
                if_spi_init_card(card);

                enable_irq(card->spi->irq);

                /* And resume it ... */
                lbs_resume(card->priv);

                card->suspended = 0;
        }
}

static int if_spi_probe(struct spi_device *spi)
{
        struct if_spi_card *card;
        struct lbs_private *priv = NULL;
        struct libertas_spi_platform_data *pdata = spi->dev.platform_data;
        int err = 0;

        lbs_deb_enter(LBS_DEB_SPI);

        if (!pdata) {
                err = -EINVAL;
                goto out;
        }

        if (pdata->setup) {
                err = pdata->setup(spi);
                if (err)
                        goto out;
        }

        /* Allocate card structure to represent this specific device */
        card = kzalloc(sizeof(struct if_spi_card), GFP_KERNEL);
        if (!card) {
                err = -ENOMEM;
                goto teardown;
        }
        spi_set_drvdata(spi, card);
        card->pdata = pdata;
        card->spi = spi;
        card->prev_xfer_time = jiffies;

        INIT_LIST_HEAD(&card->cmd_packet_list);
        INIT_LIST_HEAD(&card->data_packet_list);
        spin_lock_init(&card->buffer_lock);

        /* Initialize the SPI Interface Unit */

        /* Firmware load */
        err = if_spi_init_card(card);
        if (err)
                goto free_card;

        /*
         * Register our card with libertas.
         * This will call alloc_etherdev.
         */
        priv = lbs_add_card(card, &spi->dev);
        if (!priv) {
                err = -ENOMEM;
                goto free_card;
        }
        card->priv = priv;
        priv->setup_fw_on_resume = 1;
        priv->card = card;
        priv->hw_host_to_card = if_spi_host_to_card;
        priv->enter_deep_sleep = NULL;
        priv->exit_deep_sleep = NULL;
        priv->reset_deep_sleep_wakeup = NULL;
        priv->fw_ready = 1;

        /* Initialize interrupt handling stuff. */
        card->workqueue = create_workqueue("libertas_spi");
        INIT_WORK(&card->packet_work, if_spi_host_to_card_worker);
        INIT_WORK(&card->resume_work, if_spi_resume_worker);

        err = request_irq(spi->irq, if_spi_host_interrupt,
                        IRQF_TRIGGER_FALLING, "libertas_spi", card);
        if (err) {
                pr_err("can't get host irq line-- request_irq failed\n");
                goto terminate_workqueue;
        }

        /*
         * Start the card.
         * This will call register_netdev, and we'll start
         * getting interrupts...
         */
        err = lbs_start_card(priv);
        if (err)
                goto release_irq;

        lbs_deb_spi("Finished initializing WLAN module.\n");

        /* successful exit */
        goto out;

release_irq:
        free_irq(spi->irq, card);
terminate_workqueue:
        flush_workqueue(card->workqueue);
        destroy_workqueue(card->workqueue);
        lbs_remove_card(priv); /* will call free_netdev */
free_card:
        free_if_spi_card(card);
teardown:
        if (pdata->teardown)
                pdata->teardown(spi);
out:
        lbs_deb_leave_args(LBS_DEB_SPI, "err %d\n", err);
        return err;
}

static int libertas_spi_remove(struct spi_device *spi)
{
        struct if_spi_card *card = spi_get_drvdata(spi);
        struct lbs_private *priv = card->priv;

        lbs_deb_spi("libertas_spi_remove\n");
        lbs_deb_enter(LBS_DEB_SPI);

        cancel_work_sync(&card->resume_work);

        lbs_stop_card(priv);
        lbs_remove_card(priv); /* will call free_netdev */

        free_irq(spi->irq, card);
        flush_workqueue(card->workqueue);
        destroy_workqueue(card->workqueue);
        if (card->pdata->teardown)
                card->pdata->teardown(spi);
        free_if_spi_card(card);
        lbs_deb_leave(LBS_DEB_SPI);
        return 0;
}

static int if_spi_suspend(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct if_spi_card *card = spi_get_drvdata(spi);

        if (!card->suspended) {
                lbs_suspend(card->priv);
                flush_workqueue(card->workqueue);
                disable_irq(spi->irq);

                if (card->pdata->teardown)
                        card->pdata->teardown(spi);
                card->suspended = 1;
        }

        return 0;
}

static int if_spi_resume(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct if_spi_card *card = spi_get_drvdata(spi);

        /* Schedule delayed work */
        schedule_work(&card->resume_work);

        return 0;
}

static const struct dev_pm_ops if_spi_pm_ops = {
        .suspend        = if_spi_suspend,
        .resume         = if_spi_resume,
};

static struct spi_driver libertas_spi_driver = {
        .probe  = if_spi_probe,
        .remove = libertas_spi_remove,
        .driver = {
                .name   = "libertas_spi",
                .owner  = THIS_MODULE,
                .pm     = &if_spi_pm_ops,
        },
};

/*
 * Module functions
 */

static int __init if_spi_init_module(void)
{
        int ret = 0;
        lbs_deb_enter(LBS_DEB_SPI);
        printk(KERN_INFO "libertas_spi: Libertas SPI driver\n");
        ret = spi_register_driver(&libertas_spi_driver);
        lbs_deb_leave(LBS_DEB_SPI);
        return ret;
}

static void __exit if_spi_exit_module(void)
{
        lbs_deb_enter(LBS_DEB_SPI);
        spi_unregister_driver(&libertas_spi_driver);
        lbs_deb_leave(LBS_DEB_SPI);
}

module_init(if_spi_init_module);
module_exit(if_spi_exit_module);

MODULE_DESCRIPTION("Libertas SPI WLAN Driver");
MODULE_AUTHOR("Andrey Yurovsky <andrey@cozybit.com>, "
              "Colin McCabe <colin@cozybit.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:libertas_spi");