// SPDX-License-Identifier: GPL-2.0-only
/*
 * Intel IXP4xx HSS (synchronous serial port) driver for Linux
 *
 * Copyright (C) 2007-2008 Krzysztof Hałasa <khc@pm.waw.pl>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/cdev.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/fs.h>
#include <linux/hdlc.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/platform_data/wan_ixp4xx_hss.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/soc/ixp4xx/npe.h>
#include <linux/soc/ixp4xx/qmgr.h>
#include <linux/soc/ixp4xx/cpu.h>

#define DEBUG_DESC              0
#define DEBUG_RX                0
#define DEBUG_TX                0
#define DEBUG_PKT_BYTES         0
#define DEBUG_CLOSE             0

#define DRV_NAME                "ixp4xx_hss"

#define PKT_EXTRA_FLAGS         0 /* orig 1 */
#define PKT_NUM_PIPES           1 /* 1, 2 or 4 */
#define PKT_PIPE_FIFO_SIZEW     4 /* total 4 dwords per HSS */

#define RX_DESCS                16 /* also length of all RX queues */
#define TX_DESCS                16 /* also length of all TX queues */

#define POOL_ALLOC_SIZE         (sizeof(struct desc) * (RX_DESCS + TX_DESCS))
#define RX_SIZE                 (HDLC_MAX_MRU + 4) /* NPE needs more space */
#define MAX_CLOSE_WAIT          1000 /* microseconds */
#define HSS_COUNT               2
#define FRAME_SIZE              256 /* doesn't matter at this point */
#define FRAME_OFFSET            0
#define MAX_CHANNELS            (FRAME_SIZE / 8)

#define NAPI_WEIGHT             16

/* Queue IDs */
#define HSS0_CHL_RXTRIG_QUEUE   12      /* orig size = 32 dwords */
#define HSS0_PKT_RX_QUEUE       13      /* orig size = 32 dwords */
#define HSS0_PKT_TX0_QUEUE      14      /* orig size = 16 dwords */
#define HSS0_PKT_TX1_QUEUE      15
#define HSS0_PKT_TX2_QUEUE      16
#define HSS0_PKT_TX3_QUEUE      17
#define HSS0_PKT_RXFREE0_QUEUE  18      /* orig size = 16 dwords */
#define HSS0_PKT_RXFREE1_QUEUE  19
#define HSS0_PKT_RXFREE2_QUEUE  20
#define HSS0_PKT_RXFREE3_QUEUE  21
#define HSS0_PKT_TXDONE_QUEUE   22      /* orig size = 64 dwords */

#define HSS1_CHL_RXTRIG_QUEUE   10
#define HSS1_PKT_RX_QUEUE       0
#define HSS1_PKT_TX0_QUEUE      5
#define HSS1_PKT_TX1_QUEUE      6
#define HSS1_PKT_TX2_QUEUE      7
#define HSS1_PKT_TX3_QUEUE      8
#define HSS1_PKT_RXFREE0_QUEUE  1
#define HSS1_PKT_RXFREE1_QUEUE  2
#define HSS1_PKT_RXFREE2_QUEUE  3
#define HSS1_PKT_RXFREE3_QUEUE  4
#define HSS1_PKT_TXDONE_QUEUE   9

#define NPE_PKT_MODE_HDLC               0
#define NPE_PKT_MODE_RAW                1
#define NPE_PKT_MODE_56KMODE            2
#define NPE_PKT_MODE_56KENDIAN_MSB      4

/* PKT_PIPE_HDLC_CFG_WRITE flags */
#define PKT_HDLC_IDLE_ONES              0x1 /* default = flags */
#define PKT_HDLC_CRC_32                 0x2 /* default = CRC-16 */
#define PKT_HDLC_MSB_ENDIAN             0x4 /* default = LE */

/* hss_config, PCRs */
/* Frame sync sampling, default = active low */
#define PCR_FRM_SYNC_ACTIVE_HIGH        0x40000000
#define PCR_FRM_SYNC_FALLINGEDGE        0x80000000
#define PCR_FRM_SYNC_RISINGEDGE         0xC0000000

/* Frame sync pin: input (default) or output generated off a given clk edge */
#define PCR_FRM_SYNC_OUTPUT_FALLING     0x20000000
#define PCR_FRM_SYNC_OUTPUT_RISING      0x30000000

/* Frame and data clock sampling on edge, default = falling */
#define PCR_FCLK_EDGE_RISING            0x08000000
#define PCR_DCLK_EDGE_RISING            0x04000000

/* Clock direction, default = input */
#define PCR_SYNC_CLK_DIR_OUTPUT         0x02000000

/* Generate/Receive frame pulses, default = enabled */
#define PCR_FRM_PULSE_DISABLED          0x01000000

 /* Data rate is full (default) or half the configured clk speed */
#define PCR_HALF_CLK_RATE               0x00200000

/* Invert data between NPE and HSS FIFOs? (default = no) */
#define PCR_DATA_POLARITY_INVERT        0x00100000

/* TX/RX endianness, default = LSB */
#define PCR_MSB_ENDIAN                  0x00080000

/* Normal (default) / open drain mode (TX only) */
#define PCR_TX_PINS_OPEN_DRAIN          0x00040000

/* No framing bit transmitted and expected on RX? (default = framing bit) */
#define PCR_SOF_NO_FBIT                 0x00020000

/* Drive data pins? */
#define PCR_TX_DATA_ENABLE              0x00010000

/* Voice 56k type: drive the data pins low (default), high, high Z */
#define PCR_TX_V56K_HIGH                0x00002000
#define PCR_TX_V56K_HIGH_IMP            0x00004000

/* Unassigned type: drive the data pins low (default), high, high Z */
#define PCR_TX_UNASS_HIGH               0x00000800
#define PCR_TX_UNASS_HIGH_IMP           0x00001000

/* T1 @ 1.544MHz only: Fbit dictated in FIFO (default) or high Z */
#define PCR_TX_FB_HIGH_IMP              0x00000400

/* 56k data endiannes - which bit unused: high (default) or low */
#define PCR_TX_56KE_BIT_0_UNUSED        0x00000200

/* 56k data transmission type: 32/8 bit data (default) or 56K data */
#define PCR_TX_56KS_56K_DATA            0x00000100

/* hss_config, cCR */
/* Number of packetized clients, default = 1 */
#define CCR_NPE_HFIFO_2_HDLC            0x04000000
#define CCR_NPE_HFIFO_3_OR_4HDLC        0x08000000

/* default = no loopback */
#define CCR_LOOPBACK                    0x02000000

/* HSS number, default = 0 (first) */
#define CCR_SECOND_HSS                  0x01000000

/* hss_config, clkCR: main:10, num:10, denom:12 */
#define CLK42X_SPEED_EXP        ((0x3FF << 22) | (2 << 12) |   15) /*65 KHz*/

#define CLK42X_SPEED_512KHZ     ((130 << 22) | (2 << 12) |   15)
#define CLK42X_SPEED_1536KHZ    ((43 << 22) | (18 << 12) |   47)
#define CLK42X_SPEED_1544KHZ    ((43 << 22) | (33 << 12) |  192)
#define CLK42X_SPEED_2048KHZ    ((32 << 22) | (34 << 12) |   63)
#define CLK42X_SPEED_4096KHZ    ((16 << 22) | (34 << 12) |  127)
#define CLK42X_SPEED_8192KHZ    ((8 << 22) | (34 << 12) |  255)

#define CLK46X_SPEED_512KHZ     ((130 << 22) | (24 << 12) |  127)
#define CLK46X_SPEED_1536KHZ    ((43 << 22) | (152 << 12) |  383)
#define CLK46X_SPEED_1544KHZ    ((43 << 22) | (66 << 12) |  385)
#define CLK46X_SPEED_2048KHZ    ((32 << 22) | (280 << 12) |  511)
#define CLK46X_SPEED_4096KHZ    ((16 << 22) | (280 << 12) | 1023)
#define CLK46X_SPEED_8192KHZ    ((8 << 22) | (280 << 12) | 2047)

/* HSS_CONFIG_CLOCK_CR register consists of 3 parts:
 *     A (10 bits), B (10 bits) and C (12 bits).
 * IXP42x HSS clock generator operation (verified with an oscilloscope):
 * Each clock bit takes 7.5 ns (1 / 133.xx MHz).
 * The clock sequence consists of (C - B) states of 0s and 1s, each state is
 * A bits wide. It's followed by (B + 1) states of 0s and 1s, each state is
 * (A + 1) bits wide.
 *
 * The resulting average clock frequency (assuming 33.333 MHz oscillator) is:
 * freq = 66.666 MHz / (A + (B + 1) / (C + 1))
 * minimum freq = 66.666 MHz / (A + 1)
 * maximum freq = 66.666 MHz / A
 *
 * Example: A = 2, B = 2, C = 7, CLOCK_CR register = 2 << 22 | 2 << 12 | 7
 * freq = 66.666 MHz / (2 + (2 + 1) / (7 + 1)) = 28.07 MHz (Mb/s).
 * The clock sequence is: 1100110011 (5 doubles) 000111000 (3 triples).
 * The sequence takes (C - B) * A + (B + 1) * (A + 1) = 5 * 2 + 3 * 3 bits
 * = 19 bits (each 7.5 ns long) = 142.5 ns (then the sequence repeats).
 * The sequence consists of 4 complete clock periods, thus the average
 * frequency (= clock rate) is 4 / 142.5 ns = 28.07 MHz (Mb/s).
 * (max specified clock rate for IXP42x HSS is 8.192 Mb/s).
 */

/* hss_config, LUT entries */
#define TDMMAP_UNASSIGNED       0
#define TDMMAP_HDLC             1       /* HDLC - packetized */
#define TDMMAP_VOICE56K         2       /* Voice56K - 7-bit channelized */
#define TDMMAP_VOICE64K         3       /* Voice64K - 8-bit channelized */

/* offsets into HSS config */
#define HSS_CONFIG_TX_PCR       0x00 /* port configuration registers */
#define HSS_CONFIG_RX_PCR       0x04
#define HSS_CONFIG_CORE_CR      0x08 /* loopback control, HSS# */
#define HSS_CONFIG_CLOCK_CR     0x0C /* clock generator control */
#define HSS_CONFIG_TX_FCR       0x10 /* frame configuration registers */
#define HSS_CONFIG_RX_FCR       0x14
#define HSS_CONFIG_TX_LUT       0x18 /* channel look-up tables */
#define HSS_CONFIG_RX_LUT       0x38

/* NPE command codes */
/* writes the ConfigWord value to the location specified by offset */
#define PORT_CONFIG_WRITE               0x40

/* triggers the NPE to load the contents of the configuration table */
#define PORT_CONFIG_LOAD                0x41

/* triggers the NPE to return an HssErrorReadResponse message */
#define PORT_ERROR_READ                 0x42

/* triggers the NPE to reset internal status and enable the HssPacketized
 * operation for the flow specified by pPipe
 */
#define PKT_PIPE_FLOW_ENABLE            0x50
#define PKT_PIPE_FLOW_DISABLE           0x51
#define PKT_NUM_PIPES_WRITE             0x52
#define PKT_PIPE_FIFO_SIZEW_WRITE       0x53
#define PKT_PIPE_HDLC_CFG_WRITE         0x54
#define PKT_PIPE_IDLE_PATTERN_WRITE     0x55
#define PKT_PIPE_RX_SIZE_WRITE          0x56
#define PKT_PIPE_MODE_WRITE             0x57

/* HDLC packet status values - desc->status */
#define ERR_SHUTDOWN            1 /* stop or shutdown occurrence */
#define ERR_HDLC_ALIGN          2 /* HDLC alignment error */
#define ERR_HDLC_FCS            3 /* HDLC Frame Check Sum error */
#define ERR_RXFREE_Q_EMPTY      4 /* RX-free queue became empty while receiving
                                   * this packet (if buf_len < pkt_len)
                                   */
#define ERR_HDLC_TOO_LONG       5 /* HDLC frame size too long */
#define ERR_HDLC_ABORT          6 /* abort sequence received */
#define ERR_DISCONNECTING       7 /* disconnect is in progress */

#ifdef __ARMEB__
typedef struct sk_buff buffer_t;
#define free_buffer dev_kfree_skb
#define free_buffer_irq dev_consume_skb_irq
#else
typedef void buffer_t;
#define free_buffer kfree
#define free_buffer_irq kfree
#endif

struct port {
        struct device *dev;
        struct npe *npe;
        struct net_device *netdev;
        struct napi_struct napi;
        struct hss_plat_info *plat;
        buffer_t *rx_buff_tab[RX_DESCS], *tx_buff_tab[TX_DESCS];
        struct desc *desc_tab;  /* coherent */
        dma_addr_t desc_tab_phys;
        unsigned int id;
        unsigned int clock_type, clock_rate, loopback;
        unsigned int initialized, carrier;
        u8 hdlc_cfg;
        u32 clock_reg;
};

/* NPE message structure */
struct msg {
#ifdef __ARMEB__
        u8 cmd, unused, hss_port, index;
        union {
                struct { u8 data8a, data8b, data8c, data8d; };
                struct { u16 data16a, data16b; };
                struct { u32 data32; };
        };
#else
        u8 index, hss_port, unused, cmd;
        union {
                struct { u8 data8d, data8c, data8b, data8a; };
                struct { u16 data16b, data16a; };
                struct { u32 data32; };
        };
#endif
};

/* HDLC packet descriptor */
struct desc {
        u32 next;               /* pointer to next buffer, unused */

#ifdef __ARMEB__
        u16 buf_len;            /* buffer length */
        u16 pkt_len;            /* packet length */
        u32 data;               /* pointer to data buffer in RAM */
        u8 status;
        u8 error_count;
        u16 __reserved;
#else
        u16 pkt_len;            /* packet length */
        u16 buf_len;            /* buffer length */
        u32 data;               /* pointer to data buffer in RAM */
        u16 __reserved;
        u8 error_count;
        u8 status;
#endif
        u32 __reserved1[4];
};

#define rx_desc_phys(port, n)   ((port)->desc_tab_phys +                \
                                 (n) * sizeof(struct desc))
#define rx_desc_ptr(port, n)    (&(port)->desc_tab[n])

#define tx_desc_phys(port, n)   ((port)->desc_tab_phys +                \
                                 ((n) + RX_DESCS) * sizeof(struct desc))
#define tx_desc_ptr(port, n)    (&(port)->desc_tab[(n) + RX_DESCS])

/*****************************************************************************
 * global variables
 ****************************************************************************/

static int ports_open;
static struct dma_pool *dma_pool;
static DEFINE_SPINLOCK(npe_lock);

static const struct {
        int tx, txdone, rx, rxfree;
} queue_ids[2] = {{HSS0_PKT_TX0_QUEUE, HSS0_PKT_TXDONE_QUEUE, HSS0_PKT_RX_QUEUE,
                  HSS0_PKT_RXFREE0_QUEUE},
                 {HSS1_PKT_TX0_QUEUE, HSS1_PKT_TXDONE_QUEUE, HSS1_PKT_RX_QUEUE,
                  HSS1_PKT_RXFREE0_QUEUE},
};

/*****************************************************************************
 * utility functions
 ****************************************************************************/

static inline struct port *dev_to_port(struct net_device *dev)
{
        return dev_to_hdlc(dev)->priv;
}

#ifndef __ARMEB__
static inline void memcpy_swab32(u32 *dest, u32 *src, int cnt)
{
        int i;

        for (i = 0; i < cnt; i++)
                dest[i] = swab32(src[i]);
}
#endif

/*****************************************************************************
 * HSS access
 ****************************************************************************/

static void hss_npe_send(struct port *port, struct msg *msg, const char *what)
{
        u32 *val = (u32 *)msg;

        if (npe_send_message(port->npe, msg, what)) {
                pr_crit("HSS-%i: unable to send command [%08X:%08X] to %s\n",
                        port->id, val[0], val[1], npe_name(port->npe));
                BUG();
        }
}

static void hss_config_set_lut(struct port *port)
{
        struct msg msg;
        int ch;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;

        for (ch = 0; ch < MAX_CHANNELS; ch++) {
                msg.data32 >>= 2;
                msg.data32 |= TDMMAP_HDLC << 30;

                if (ch % 16 == 15) {
                        msg.index = HSS_CONFIG_TX_LUT + ((ch / 4) & ~3);
                        hss_npe_send(port, &msg, "HSS_SET_TX_LUT");

                        msg.index += HSS_CONFIG_RX_LUT - HSS_CONFIG_TX_LUT;
                        hss_npe_send(port, &msg, "HSS_SET_RX_LUT");
                }
        }
}

static void hss_config(struct port *port)
{
        struct msg msg;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;
        msg.index = HSS_CONFIG_TX_PCR;
        msg.data32 = PCR_FRM_PULSE_DISABLED | PCR_MSB_ENDIAN |
                PCR_TX_DATA_ENABLE | PCR_SOF_NO_FBIT;
        if (port->clock_type == CLOCK_INT)
                msg.data32 |= PCR_SYNC_CLK_DIR_OUTPUT;
        hss_npe_send(port, &msg, "HSS_SET_TX_PCR");

        msg.index = HSS_CONFIG_RX_PCR;
        msg.data32 ^= PCR_TX_DATA_ENABLE | PCR_DCLK_EDGE_RISING;
        hss_npe_send(port, &msg, "HSS_SET_RX_PCR");

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;
        msg.index = HSS_CONFIG_CORE_CR;
        msg.data32 = (port->loopback ? CCR_LOOPBACK : 0) |
                (port->id ? CCR_SECOND_HSS : 0);
        hss_npe_send(port, &msg, "HSS_SET_CORE_CR");

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;
        msg.index = HSS_CONFIG_CLOCK_CR;
        msg.data32 = port->clock_reg;
        hss_npe_send(port, &msg, "HSS_SET_CLOCK_CR");

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;
        msg.index = HSS_CONFIG_TX_FCR;
        msg.data16a = FRAME_OFFSET;
        msg.data16b = FRAME_SIZE - 1;
        hss_npe_send(port, &msg, "HSS_SET_TX_FCR");

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_WRITE;
        msg.hss_port = port->id;
        msg.index = HSS_CONFIG_RX_FCR;
        msg.data16a = FRAME_OFFSET;
        msg.data16b = FRAME_SIZE - 1;
        hss_npe_send(port, &msg, "HSS_SET_RX_FCR");

        hss_config_set_lut(port);

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_CONFIG_LOAD;
        msg.hss_port = port->id;
        hss_npe_send(port, &msg, "HSS_LOAD_CONFIG");

        if (npe_recv_message(port->npe, &msg, "HSS_LOAD_CONFIG") ||
            /* HSS_LOAD_CONFIG for port #1 returns port_id = #4 */
            msg.cmd != PORT_CONFIG_LOAD || msg.data32) {
                pr_crit("HSS-%i: HSS_LOAD_CONFIG failed\n", port->id);
                BUG();
        }

        /* HDLC may stop working without this - check FIXME */
        npe_recv_message(port->npe, &msg, "FLUSH_IT");
}

static void hss_set_hdlc_cfg(struct port *port)
{
        struct msg msg;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PKT_PIPE_HDLC_CFG_WRITE;
        msg.hss_port = port->id;
        msg.data8a = port->hdlc_cfg; /* rx_cfg */
        msg.data8b = port->hdlc_cfg | (PKT_EXTRA_FLAGS << 3); /* tx_cfg */
        hss_npe_send(port, &msg, "HSS_SET_HDLC_CFG");
}

static u32 hss_get_status(struct port *port)
{
        struct msg msg;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PORT_ERROR_READ;
        msg.hss_port = port->id;
        hss_npe_send(port, &msg, "PORT_ERROR_READ");
        if (npe_recv_message(port->npe, &msg, "PORT_ERROR_READ")) {
                pr_crit("HSS-%i: unable to read HSS status\n", port->id);
                BUG();
        }

        return msg.data32;
}

static void hss_start_hdlc(struct port *port)
{
        struct msg msg;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PKT_PIPE_FLOW_ENABLE;
        msg.hss_port = port->id;
        msg.data32 = 0;
        hss_npe_send(port, &msg, "HSS_ENABLE_PKT_PIPE");
}

static void hss_stop_hdlc(struct port *port)
{
        struct msg msg;

        memset(&msg, 0, sizeof(msg));
        msg.cmd = PKT_PIPE_FLOW_DISABLE;
        msg.hss_port = port->id;
        hss_npe_send(port, &msg, "HSS_DISABLE_PKT_PIPE");
        hss_get_status(port); /* make sure it's halted */
}

static int hss_load_firmware(struct port *port)
{
        struct msg msg;
        int err;

        if (port->initialized)
                return 0;

        if (!npe_running(port->npe)) {
                err = npe_load_firmware(port->npe, npe_name(port->npe),
                                        port->dev);
                if (err)
                        return err;
        }

        /* HDLC mode configuration */
        memset(&msg, 0, sizeof(msg));
        msg.cmd = PKT_NUM_PIPES_WRITE;
        msg.hss_port = port->id;
        msg.data8a = PKT_NUM_PIPES;
        hss_npe_send(port, &msg, "HSS_SET_PKT_PIPES");

        msg.cmd = PKT_PIPE_FIFO_SIZEW_WRITE;
        msg.data8a = PKT_PIPE_FIFO_SIZEW;
        hss_npe_send(port, &msg, "HSS_SET_PKT_FIFO");

        msg.cmd = PKT_PIPE_MODE_WRITE;
        msg.data8a = NPE_PKT_MODE_HDLC;
        /* msg.data8b = inv_mask */
        /* msg.data8c = or_mask */
        hss_npe_send(port, &msg, "HSS_SET_PKT_MODE");

        msg.cmd = PKT_PIPE_RX_SIZE_WRITE;
        msg.data16a = HDLC_MAX_MRU; /* including CRC */
        hss_npe_send(port, &msg, "HSS_SET_PKT_RX_SIZE");

        msg.cmd = PKT_PIPE_IDLE_PATTERN_WRITE;
        msg.data32 = 0x7F7F7F7F; /* ??? FIXME */
        hss_npe_send(port, &msg, "HSS_SET_PKT_IDLE");

        port->initialized = 1;
        return 0;
}

/*****************************************************************************
 * packetized (HDLC) operation
 ****************************************************************************/

static inline void debug_pkt(struct net_device *dev, const char *func,
                             u8 *data, int len)
{
#if DEBUG_PKT_BYTES
        int i;

        printk(KERN_DEBUG "%s: %s(%i)", dev->name, func, len);
        for (i = 0; i < len; i++) {
                if (i >= DEBUG_PKT_BYTES)
                        break;
                printk("%s%02X", !(i % 4) ? " " : "", data[i]);
        }
        printk("\n");
#endif
}

static inline void debug_desc(u32 phys, struct desc *desc)
{
#if DEBUG_DESC
        printk(KERN_DEBUG "%X: %X %3X %3X %08X %X %X\n",
               phys, desc->next, desc->buf_len, desc->pkt_len,
               desc->data, desc->status, desc->error_count);
#endif
}

static inline int queue_get_desc(unsigned int queue, struct port *port,
                                 int is_tx)
{
        u32 phys, tab_phys, n_desc;
        struct desc *tab;

        phys = qmgr_get_entry(queue);
        if (!phys)
                return -1;

        BUG_ON(phys & 0x1F);
        tab_phys = is_tx ? tx_desc_phys(port, 0) : rx_desc_phys(port, 0);
        tab = is_tx ? tx_desc_ptr(port, 0) : rx_desc_ptr(port, 0);
        n_desc = (phys - tab_phys) / sizeof(struct desc);
        BUG_ON(n_desc >= (is_tx ? TX_DESCS : RX_DESCS));
        debug_desc(phys, &tab[n_desc]);
        BUG_ON(tab[n_desc].next);
        return n_desc;
}

static inline void queue_put_desc(unsigned int queue, u32 phys,
                                  struct desc *desc)
{
        debug_desc(phys, desc);
        BUG_ON(phys & 0x1F);
        qmgr_put_entry(queue, phys);
        /* Don't check for queue overflow here, we've allocated sufficient
         * length and queues >= 32 don't support this check anyway.
         */
}

static inline void dma_unmap_tx(struct port *port, struct desc *desc)
{
#ifdef __ARMEB__
        dma_unmap_single(&port->netdev->dev, desc->data,
                         desc->buf_len, DMA_TO_DEVICE);
#else
        dma_unmap_single(&port->netdev->dev, desc->data & ~3,
                         ALIGN((desc->data & 3) + desc->buf_len, 4),
                         DMA_TO_DEVICE);
#endif
}

static void hss_hdlc_set_carrier(void *pdev, int carrier)
{
        struct net_device *netdev = pdev;
        struct port *port = dev_to_port(netdev);
        unsigned long flags;

        spin_lock_irqsave(&npe_lock, flags);
        port->carrier = carrier;
        if (!port->loopback) {
                if (carrier)
                        netif_carrier_on(netdev);
                else
                        netif_carrier_off(netdev);
        }
        spin_unlock_irqrestore(&npe_lock, flags);
}

static void hss_hdlc_rx_irq(void *pdev)
{
        struct net_device *dev = pdev;
        struct port *port = dev_to_port(dev);

#if DEBUG_RX
        printk(KERN_DEBUG "%s: hss_hdlc_rx_irq\n", dev->name);
#endif
        qmgr_disable_irq(queue_ids[port->id].rx);
        napi_schedule(&port->napi);
}

static int hss_hdlc_poll(struct napi_struct *napi, int budget)
{
        struct port *port = container_of(napi, struct port, napi);
        struct net_device *dev = port->netdev;
        unsigned int rxq = queue_ids[port->id].rx;
        unsigned int rxfreeq = queue_ids[port->id].rxfree;
        int received = 0;

#if DEBUG_RX
        printk(KERN_DEBUG "%s: hss_hdlc_poll\n", dev->name);
#endif

        while (received < budget) {
                struct sk_buff *skb;
                struct desc *desc;
                int n;
#ifdef __ARMEB__
                struct sk_buff *temp;
                u32 phys;
#endif

                n = queue_get_desc(rxq, port, 0);
                if (n < 0) {
#if DEBUG_RX
                        printk(KERN_DEBUG "%s: hss_hdlc_poll"
                               " napi_complete\n", dev->name);
#endif
                        napi_complete(napi);
                        qmgr_enable_irq(rxq);
                        if (!qmgr_stat_empty(rxq) &&
                            napi_reschedule(napi)) {
#if DEBUG_RX
                                printk(KERN_DEBUG "%s: hss_hdlc_poll"
                                       " napi_reschedule succeeded\n",
                                       dev->name);
#endif
                                qmgr_disable_irq(rxq);
                                continue;
                        }
#if DEBUG_RX
                        printk(KERN_DEBUG "%s: hss_hdlc_poll all done\n",
                               dev->name);
#endif
                        return received; /* all work done */
                }

                desc = rx_desc_ptr(port, n);
#if 0 /* FIXME - error_count counts modulo 256, perhaps we should use it */
                if (desc->error_count)
                        printk(KERN_DEBUG "%s: hss_hdlc_poll status 0x%02X"
                               " errors %u\n", dev->name, desc->status,
                               desc->error_count);
#endif
                skb = NULL;
                switch (desc->status) {
                case 0:
#ifdef __ARMEB__
                        skb = netdev_alloc_skb(dev, RX_SIZE);
                        if (skb) {
                                phys = dma_map_single(&dev->dev, skb->data,
                                                      RX_SIZE,
                                                      DMA_FROM_DEVICE);
                                if (dma_mapping_error(&dev->dev, phys)) {
                                        dev_kfree_skb(skb);
                                        skb = NULL;
                                }
                        }
#else
                        skb = netdev_alloc_skb(dev, desc->pkt_len);
#endif
                        if (!skb)
                                dev->stats.rx_dropped++;
                        break;
                case ERR_HDLC_ALIGN:
                case ERR_HDLC_ABORT:
                        dev->stats.rx_frame_errors++;
                        dev->stats.rx_errors++;
                        break;
                case ERR_HDLC_FCS:
                        dev->stats.rx_crc_errors++;
                        dev->stats.rx_errors++;
                        break;
                case ERR_HDLC_TOO_LONG:
                        dev->stats.rx_length_errors++;
                        dev->stats.rx_errors++;
                        break;
                default:        /* FIXME - remove printk */
                        netdev_err(dev, "hss_hdlc_poll: status 0x%02X errors %u\n",
                                   desc->status, desc->error_count);
                        dev->stats.rx_errors++;
                }

                if (!skb) {
                        /* put the desc back on RX-ready queue */
                        desc->buf_len = RX_SIZE;
                        desc->pkt_len = desc->status = 0;
                        queue_put_desc(rxfreeq, rx_desc_phys(port, n), desc);
                        continue;
                }

                /* process received frame */
#ifdef __ARMEB__
                temp = skb;
                skb = port->rx_buff_tab[n];
                dma_unmap_single(&dev->dev, desc->data,
                                 RX_SIZE, DMA_FROM_DEVICE);
#else
                dma_sync_single_for_cpu(&dev->dev, desc->data,
                                        RX_SIZE, DMA_FROM_DEVICE);
                memcpy_swab32((u32 *)skb->data, (u32 *)port->rx_buff_tab[n],
                              ALIGN(desc->pkt_len, 4) / 4);
#endif
                skb_put(skb, desc->pkt_len);

                debug_pkt(dev, "hss_hdlc_poll", skb->data, skb->len);

                skb->protocol = hdlc_type_trans(skb, dev);
                dev->stats.rx_packets++;
                dev->stats.rx_bytes += skb->len;
                netif_receive_skb(skb);

                /* put the new buffer on RX-free queue */
#ifdef __ARMEB__
                port->rx_buff_tab[n] = temp;
                desc->data = phys;
#endif
                desc->buf_len = RX_SIZE;
                desc->pkt_len = 0;
                queue_put_desc(rxfreeq, rx_desc_phys(port, n), desc);
                received++;
        }
#if DEBUG_RX
        printk(KERN_DEBUG "hss_hdlc_poll: end, not all work done\n");
#endif
        return received;        /* not all work done */
}

static void hss_hdlc_txdone_irq(void *pdev)
{
        struct net_device *dev = pdev;
        struct port *port = dev_to_port(dev);
        int n_desc;

#if DEBUG_TX
        printk(KERN_DEBUG DRV_NAME ": hss_hdlc_txdone_irq\n");
#endif
        while ((n_desc = queue_get_desc(queue_ids[port->id].txdone,
                                        port, 1)) >= 0) {
                struct desc *desc;
                int start;

                desc = tx_desc_ptr(port, n_desc);

                dev->stats.tx_packets++;
                dev->stats.tx_bytes += desc->pkt_len;

                dma_unmap_tx(port, desc);
#if DEBUG_TX
                printk(KERN_DEBUG "%s: hss_hdlc_txdone_irq free %p\n",
                       dev->name, port->tx_buff_tab[n_desc]);
#endif
                free_buffer_irq(port->tx_buff_tab[n_desc]);
                port->tx_buff_tab[n_desc] = NULL;

                start = qmgr_stat_below_low_watermark(port->plat->txreadyq);
                queue_put_desc(port->plat->txreadyq,
                               tx_desc_phys(port, n_desc), desc);
                if (start) { /* TX-ready queue was empty */
#if DEBUG_TX
                        printk(KERN_DEBUG "%s: hss_hdlc_txdone_irq xmit"
                               " ready\n", dev->name);
#endif
                        netif_wake_queue(dev);
                }
        }
}

static int hss_hdlc_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct port *port = dev_to_port(dev);
        unsigned int txreadyq = port->plat->txreadyq;
        int len, offset, bytes, n;
        void *mem;
        u32 phys;
        struct desc *desc;

#if DEBUG_TX
        printk(KERN_DEBUG "%s: hss_hdlc_xmit\n", dev->name);
#endif

        if (unlikely(skb->len > HDLC_MAX_MRU)) {
                dev_kfree_skb(skb);
                dev->stats.tx_errors++;
                return NETDEV_TX_OK;
        }

        debug_pkt(dev, "hss_hdlc_xmit", skb->data, skb->len);

        len = skb->len;
#ifdef __ARMEB__
        offset = 0; /* no need to keep alignment */
        bytes = len;
        mem = skb->data;
#else
        offset = (int)skb->data & 3; /* keep 32-bit alignment */
        bytes = ALIGN(offset + len, 4);
        mem = kmalloc(bytes, GFP_ATOMIC);
        if (!mem) {
                dev_kfree_skb(skb);
                dev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }
        memcpy_swab32(mem, (u32 *)((uintptr_t)skb->data & ~3), bytes / 4);
        dev_kfree_skb(skb);
#endif

        phys = dma_map_single(&dev->dev, mem, bytes, DMA_TO_DEVICE);
        if (dma_mapping_error(&dev->dev, phys)) {
#ifdef __ARMEB__
                dev_kfree_skb(skb);
#else
                kfree(mem);
#endif
                dev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        n = queue_get_desc(txreadyq, port, 1);
        BUG_ON(n < 0);
        desc = tx_desc_ptr(port, n);

#ifdef __ARMEB__
        port->tx_buff_tab[n] = skb;
#else
        port->tx_buff_tab[n] = mem;
#endif
        desc->data = phys + offset;
        desc->buf_len = desc->pkt_len = len;

        wmb();
        queue_put_desc(queue_ids[port->id].tx, tx_desc_phys(port, n), desc);

        if (qmgr_stat_below_low_watermark(txreadyq)) { /* empty */
#if DEBUG_TX
                printk(KERN_DEBUG "%s: hss_hdlc_xmit queue full\n", dev->name);
#endif
                netif_stop_queue(dev);
                /* we could miss TX ready interrupt */
                if (!qmgr_stat_below_low_watermark(txreadyq)) {
#if DEBUG_TX
                        printk(KERN_DEBUG "%s: hss_hdlc_xmit ready again\n",
                               dev->name);
#endif
                        netif_wake_queue(dev);
                }
        }

#if DEBUG_TX
        printk(KERN_DEBUG "%s: hss_hdlc_xmit end\n", dev->name);
#endif
        return NETDEV_TX_OK;
}

static int request_hdlc_queues(struct port *port)
{
        int err;

        err = qmgr_request_queue(queue_ids[port->id].rxfree, RX_DESCS, 0, 0,
                                 "%s:RX-free", port->netdev->name);
        if (err)
                return err;

        err = qmgr_request_queue(queue_ids[port->id].rx, RX_DESCS, 0, 0,
                                 "%s:RX", port->netdev->name);
        if (err)
                goto rel_rxfree;

        err = qmgr_request_queue(queue_ids[port->id].tx, TX_DESCS, 0, 0,
                                 "%s:TX", port->netdev->name);
        if (err)
                goto rel_rx;

        err = qmgr_request_queue(port->plat->txreadyq, TX_DESCS, 0, 0,
                                 "%s:TX-ready", port->netdev->name);
        if (err)
                goto rel_tx;

        err = qmgr_request_queue(queue_ids[port->id].txdone, TX_DESCS, 0, 0,
                                 "%s:TX-done", port->netdev->name);
        if (err)
                goto rel_txready;
        return 0;

rel_txready:
        qmgr_release_queue(port->plat->txreadyq);
rel_tx:
        qmgr_release_queue(queue_ids[port->id].tx);
rel_rx:
        qmgr_release_queue(queue_ids[port->id].rx);
rel_rxfree:
        qmgr_release_queue(queue_ids[port->id].rxfree);
        printk(KERN_DEBUG "%s: unable to request hardware queues\n",
               port->netdev->name);
        return err;
}

static void release_hdlc_queues(struct port *port)
{
        qmgr_release_queue(queue_ids[port->id].rxfree);
        qmgr_release_queue(queue_ids[port->id].rx);
        qmgr_release_queue(queue_ids[port->id].txdone);
        qmgr_release_queue(queue_ids[port->id].tx);
        qmgr_release_queue(port->plat->txreadyq);
}

static int init_hdlc_queues(struct port *port)
{
        int i;

        if (!ports_open) {
                dma_pool = dma_pool_create(DRV_NAME, &port->netdev->dev,
                                           POOL_ALLOC_SIZE, 32, 0);
                if (!dma_pool)
                        return -ENOMEM;
        }

        port->desc_tab = dma_pool_zalloc(dma_pool, GFP_KERNEL,
                                        &port->desc_tab_phys);
        if (!port->desc_tab)
                return -ENOMEM;
        memset(port->rx_buff_tab, 0, sizeof(port->rx_buff_tab)); /* tables */
        memset(port->tx_buff_tab, 0, sizeof(port->tx_buff_tab));

        /* Setup RX buffers */
        for (i = 0; i < RX_DESCS; i++) {
                struct desc *desc = rx_desc_ptr(port, i);
                buffer_t *buff;
                void *data;
#ifdef __ARMEB__
                buff = netdev_alloc_skb(port->netdev, RX_SIZE);
                if (!buff)
                        return -ENOMEM;
                data = buff->data;
#else
                buff = kmalloc(RX_SIZE, GFP_KERNEL);
                if (!buff)
                        return -ENOMEM;
                data = buff;
#endif

                desc->buf_len = RX_SIZE;
                desc->data = dma_map_single(&port->netdev->dev, data,
                                            RX_SIZE, DMA_FROM_DEVICE);
                if (dma_mapping_error(&port->netdev->dev, desc->data)) {
                        free_buffer(buff);
                        return -EIO;
                }
                port->rx_buff_tab[i] = buff;
        }

        return 0;
}

static void destroy_hdlc_queues(struct port *port)
{
        int i;

        if (port->desc_tab) {
                for (i = 0; i < RX_DESCS; i++) {
                        struct desc *desc = rx_desc_ptr(port, i);
                        buffer_t *buff = port->rx_buff_tab[i];

                        if (buff) {
                                dma_unmap_single(&port->netdev->dev,
                                                 desc->data, RX_SIZE,
                                                 DMA_FROM_DEVICE);
                                free_buffer(buff);
                        }
                }
                for (i = 0; i < TX_DESCS; i++) {
                        struct desc *desc = tx_desc_ptr(port, i);
                        buffer_t *buff = port->tx_buff_tab[i];

                        if (buff) {
                                dma_unmap_tx(port, desc);
                                free_buffer(buff);
                        }
                }
                dma_pool_free(dma_pool, port->desc_tab, port->desc_tab_phys);
                port->desc_tab = NULL;
        }

        if (!ports_open && dma_pool) {
                dma_pool_destroy(dma_pool);
                dma_pool = NULL;
        }
}

static int hss_hdlc_open(struct net_device *dev)
{
        struct port *port = dev_to_port(dev);
        unsigned long flags;
        int i, err = 0;

        err = hdlc_open(dev);
        if (err)
                return err;

        err = hss_load_firmware(port);
        if (err)
                goto err_hdlc_close;

        err = request_hdlc_queues(port);
        if (err)
                goto err_hdlc_close;

        err = init_hdlc_queues(port);
        if (err)
                goto err_destroy_queues;

        spin_lock_irqsave(&npe_lock, flags);
        if (port->plat->open) {
                err = port->plat->open(port->id, dev, hss_hdlc_set_carrier);
                if (err)
                        goto err_unlock;
        }

        spin_unlock_irqrestore(&npe_lock, flags);

        /* Populate queues with buffers, no failure after this point */
        for (i = 0; i < TX_DESCS; i++)
                queue_put_desc(port->plat->txreadyq,
                               tx_desc_phys(port, i), tx_desc_ptr(port, i));

        for (i = 0; i < RX_DESCS; i++)
                queue_put_desc(queue_ids[port->id].rxfree,
                               rx_desc_phys(port, i), rx_desc_ptr(port, i));

        napi_enable(&port->napi);
        netif_start_queue(dev);

        qmgr_set_irq(queue_ids[port->id].rx, QUEUE_IRQ_SRC_NOT_EMPTY,
                     hss_hdlc_rx_irq, dev);

        qmgr_set_irq(queue_ids[port->id].txdone, QUEUE_IRQ_SRC_NOT_EMPTY,
                     hss_hdlc_txdone_irq, dev);
        qmgr_enable_irq(queue_ids[port->id].txdone);

        ports_open++;

        hss_set_hdlc_cfg(port);
        hss_config(port);

        hss_start_hdlc(port);

        /* we may already have RX data, enables IRQ */
        napi_schedule(&port->napi);
        return 0;

err_unlock:
        spin_unlock_irqrestore(&npe_lock, flags);
err_destroy_queues:
        destroy_hdlc_queues(port);
        release_hdlc_queues(port);
err_hdlc_close:
        hdlc_close(dev);
        return err;
}

static int hss_hdlc_close(struct net_device *dev)
{
        struct port *port = dev_to_port(dev);
        unsigned long flags;
        int i, buffs = RX_DESCS; /* allocated RX buffers */

        spin_lock_irqsave(&npe_lock, flags);
        ports_open--;
        qmgr_disable_irq(queue_ids[port->id].rx);
        netif_stop_queue(dev);
        napi_disable(&port->napi);

        hss_stop_hdlc(port);

        while (queue_get_desc(queue_ids[port->id].rxfree, port, 0) >= 0)
                buffs--;
        while (queue_get_desc(queue_ids[port->id].rx, port, 0) >= 0)
                buffs--;

        if (buffs)
                netdev_crit(dev, "unable to drain RX queue, %i buffer(s) left in NPE\n",
                            buffs);

        buffs = TX_DESCS;
        while (queue_get_desc(queue_ids[port->id].tx, port, 1) >= 0)
                buffs--; /* cancel TX */

        i = 0;
        do {
                while (queue_get_desc(port->plat->txreadyq, port, 1) >= 0)
                        buffs--;
                if (!buffs)
                        break;
        } while (++i < MAX_CLOSE_WAIT);

        if (buffs)
                netdev_crit(dev, "unable to drain TX queue, %i buffer(s) left in NPE\n",
                            buffs);
#if DEBUG_CLOSE
        if (!buffs)
                printk(KERN_DEBUG "Draining TX queues took %i cycles\n", i);
#endif
        qmgr_disable_irq(queue_ids[port->id].txdone);

        if (port->plat->close)
                port->plat->close(port->id, dev);
        spin_unlock_irqrestore(&npe_lock, flags);

        destroy_hdlc_queues(port);
        release_hdlc_queues(port);
        hdlc_close(dev);
        return 0;
}

static int hss_hdlc_attach(struct net_device *dev, unsigned short encoding,
                           unsigned short parity)
{
        struct port *port = dev_to_port(dev);

        if (encoding != ENCODING_NRZ)
                return -EINVAL;

        switch (parity) {
        case PARITY_CRC16_PR1_CCITT:
                port->hdlc_cfg = 0;
                return 0;

        case PARITY_CRC32_PR1_CCITT:
                port->hdlc_cfg = PKT_HDLC_CRC_32;
                return 0;

        default:
                return -EINVAL;
        }
}

static u32 check_clock(u32 timer_freq, u32 rate, u32 a, u32 b, u32 c,
                       u32 *best, u32 *best_diff, u32 *reg)
{
        /* a is 10-bit, b is 10-bit, c is 12-bit */
        u64 new_rate;
        u32 new_diff;

        new_rate = timer_freq * (u64)(c + 1);
        do_div(new_rate, a * (c + 1) + b + 1);
        new_diff = abs((u32)new_rate - rate);

        if (new_diff < *best_diff) {
                *best = new_rate;
                *best_diff = new_diff;
                *reg = (a << 22) | (b << 12) | c;
        }
        return new_diff;
}

static void find_best_clock(u32 timer_freq, u32 rate, u32 *best, u32 *reg)
{
        u32 a, b, diff = 0xFFFFFFFF;

        a = timer_freq / rate;

        if (a > 0x3FF) { /* 10-bit value - we can go as slow as ca. 65 kb/s */
                check_clock(timer_freq, rate, 0x3FF, 1, 1, best, &diff, reg);
                return;
        }
        if (a == 0) { /* > 66.666 MHz */
                a = 1; /* minimum divider is 1 (a = 0, b = 1, c = 1) */
                rate = timer_freq;
        }

        if (rate * a == timer_freq) { /* don't divide by 0 later */
                check_clock(timer_freq, rate, a - 1, 1, 1, best, &diff, reg);
                return;
        }

        for (b = 0; b < 0x400; b++) {
                u64 c = (b + 1) * (u64)rate;

                do_div(c, timer_freq - rate * a);
                c--;
                if (c >= 0xFFF) { /* 12-bit - no need to check more 'b's */
                        if (b == 0 && /* also try a bit higher rate */
                            !check_clock(timer_freq, rate, a - 1, 1, 1, best,
                                         &diff, reg))
                                return;
                        check_clock(timer_freq, rate, a, b, 0xFFF, best,
                                    &diff, reg);
                        return;
                }
                if (!check_clock(timer_freq, rate, a, b, c, best, &diff, reg))
                        return;
                if (!check_clock(timer_freq, rate, a, b, c + 1, best, &diff,
                                 reg))
                        return;
        }
}

static int hss_hdlc_ioctl(struct net_device *dev, struct if_settings *ifs)
{
        const size_t size = sizeof(sync_serial_settings);
        sync_serial_settings new_line;
        sync_serial_settings __user *line = ifs->ifs_ifsu.sync;
        struct port *port = dev_to_port(dev);
        unsigned long flags;
        int clk;

        switch (ifs->type) {
        case IF_GET_IFACE:
                ifs->type = IF_IFACE_V35;
                if (ifs->size < size) {
                        ifs->size = size; /* data size wanted */
                        return -ENOBUFS;
                }
                memset(&new_line, 0, sizeof(new_line));
                new_line.clock_type = port->clock_type;
                new_line.clock_rate = port->clock_rate;
                new_line.loopback = port->loopback;
                if (copy_to_user(line, &new_line, size))
                        return -EFAULT;
                return 0;

        case IF_IFACE_SYNC_SERIAL:
        case IF_IFACE_V35:
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (copy_from_user(&new_line, line, size))
                        return -EFAULT;

                clk = new_line.clock_type;
                if (port->plat->set_clock)
                        clk = port->plat->set_clock(port->id, clk);

                if (clk != CLOCK_EXT && clk != CLOCK_INT)
                        return -EINVAL; /* No such clock setting */

                if (new_line.loopback != 0 && new_line.loopback != 1)
                        return -EINVAL;

                port->clock_type = clk; /* Update settings */
                if (clk == CLOCK_INT) {
                        find_best_clock(port->plat->timer_freq,
                                        new_line.clock_rate,
                                        &port->clock_rate, &port->clock_reg);
                } else {
                        port->clock_rate = 0;
                        port->clock_reg = CLK42X_SPEED_2048KHZ;
                }
                port->loopback = new_line.loopback;

                spin_lock_irqsave(&npe_lock, flags);

                if (dev->flags & IFF_UP)
                        hss_config(port);

                if (port->loopback || port->carrier)
                        netif_carrier_on(port->netdev);
                else
                        netif_carrier_off(port->netdev);
                spin_unlock_irqrestore(&npe_lock, flags);

                return 0;

        default:
                return hdlc_ioctl(dev, ifs);
        }
}

/*****************************************************************************
 * initialization
 ****************************************************************************/

static const struct net_device_ops hss_hdlc_ops = {
        .ndo_open       = hss_hdlc_open,
        .ndo_stop       = hss_hdlc_close,
        .ndo_start_xmit = hdlc_start_xmit,
        .ndo_siocwandev = hss_hdlc_ioctl,
};

static int hss_init_one(struct platform_device *pdev)
{
        struct port *port;
        struct net_device *dev;
        hdlc_device *hdlc;
        int err;

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

        port->npe = npe_request(0);
        if (!port->npe) {
                err = -ENODEV;
                goto err_free;
        }

        dev = alloc_hdlcdev(port);
        port->netdev = alloc_hdlcdev(port);
        if (!port->netdev) {
                err = -ENOMEM;
                goto err_plat;
        }

        SET_NETDEV_DEV(dev, &pdev->dev);
        hdlc = dev_to_hdlc(dev);
        hdlc->attach = hss_hdlc_attach;
        hdlc->xmit = hss_hdlc_xmit;
        dev->netdev_ops = &hss_hdlc_ops;
        dev->tx_queue_len = 100;
        port->clock_type = CLOCK_EXT;
        port->clock_rate = 0;
        port->clock_reg = CLK42X_SPEED_2048KHZ;
        port->id = pdev->id;
        port->dev = &pdev->dev;
        port->plat = pdev->dev.platform_data;
        netif_napi_add(dev, &port->napi, hss_hdlc_poll, NAPI_WEIGHT);

        err = register_hdlc_device(dev);
        if (err)
                goto err_free_netdev;

        platform_set_drvdata(pdev, port);

        netdev_info(dev, "initialized\n");
        return 0;

err_free_netdev:
        free_netdev(dev);
err_plat:
        npe_release(port->npe);
err_free:
        kfree(port);
        return err;
}

static int hss_remove_one(struct platform_device *pdev)
{
        struct port *port = platform_get_drvdata(pdev);

        unregister_hdlc_device(port->netdev);
        free_netdev(port->netdev);
        npe_release(port->npe);
        kfree(port);
        return 0;
}

static struct platform_driver ixp4xx_hss_driver = {
        .driver.name    = DRV_NAME,
        .probe          = hss_init_one,
        .remove         = hss_remove_one,
};

static int __init hss_init_module(void)
{
        if ((ixp4xx_read_feature_bits() &
             (IXP4XX_FEATURE_HDLC | IXP4XX_FEATURE_HSS)) !=
            (IXP4XX_FEATURE_HDLC | IXP4XX_FEATURE_HSS))
                return -ENODEV;

        return platform_driver_register(&ixp4xx_hss_driver);
}

static void __exit hss_cleanup_module(void)
{
        platform_driver_unregister(&ixp4xx_hss_driver);
}

MODULE_AUTHOR("Krzysztof Halasa");
MODULE_DESCRIPTION("Intel IXP4xx HSS driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:ixp4xx_hss");
module_init(hss_init_module);
module_exit(hss_cleanup_module);