// SPDX-License-Identifier: GPL-2.0-only
/*
 * Xilinx SystemACE device driver
 *
 * Copyright 2007 Secret Lab Technologies Ltd.
 */

/*
 * The SystemACE chip is designed to configure FPGAs by loading an FPGA
 * bitstream from a file on a CF card and squirting it into FPGAs connected
 * to the SystemACE JTAG chain.  It also has the advantage of providing an
 * MPU interface which can be used to control the FPGA configuration process
 * and to use the attached CF card for general purpose storage.
 *
 * This driver is a block device driver for the SystemACE.
 *
 * Initialization:
 *    The driver registers itself as a platform_device driver at module
 *    load time.  The platform bus will take care of calling the
 *    ace_probe() method for all SystemACE instances in the system.  Any
 *    number of SystemACE instances are supported.  ace_probe() calls
 *    ace_setup() which initialized all data structures, reads the CF
 *    id structure and registers the device.
 *
 * Processing:
 *    Just about all of the heavy lifting in this driver is performed by
 *    a Finite State Machine (FSM).  The driver needs to wait on a number
 *    of events; some raised by interrupts, some which need to be polled
 *    for.  Describing all of the behaviour in a FSM seems to be the
 *    easiest way to keep the complexity low and make it easy to
 *    understand what the driver is doing.  If the block ops or the
 *    request function need to interact with the hardware, then they
 *    simply need to flag the request and kick of FSM processing.
 *
 *    The FSM itself is atomic-safe code which can be run from any
 *    context.  The general process flow is:
 *    1. obtain the ace->lock spinlock.
 *    2. loop on ace_fsm_dostate() until the ace->fsm_continue flag is
 *       cleared.
 *    3. release the lock.
 *
 *    Individual states do not sleep in any way.  If a condition needs to
 *    be waited for then the state much clear the fsm_continue flag and
 *    either schedule the FSM to be run again at a later time, or expect
 *    an interrupt to call the FSM when the desired condition is met.
 *
 *    In normal operation, the FSM is processed at interrupt context
 *    either when the driver's tasklet is scheduled, or when an irq is
 *    raised by the hardware.  The tasklet can be scheduled at any time.
 *    The request method in particular schedules the tasklet when a new
 *    request has been indicated by the block layer.  Once started, the
 *    FSM proceeds as far as it can processing the request until it
 *    needs on a hardware event.  At this point, it must yield execution.
 *
 *    A state has two options when yielding execution:
 *    1. ace_fsm_yield()
 *       - Call if need to poll for event.
 *       - clears the fsm_continue flag to exit the processing loop
 *       - reschedules the tasklet to run again as soon as possible
 *    2. ace_fsm_yieldirq()
 *       - Call if an irq is expected from the HW
 *       - clears the fsm_continue flag to exit the processing loop
 *       - does not reschedule the tasklet so the FSM will not be processed
 *         again until an irq is received.
 *    After calling a yield function, the state must return control back
 *    to the FSM main loop.
 *
 *    Additionally, the driver maintains a kernel timer which can process
 *    the FSM.  If the FSM gets stalled, typically due to a missed
 *    interrupt, then the kernel timer will expire and the driver can
 *    continue where it left off.
 *
 * To Do:
 *    - Add FPGA configuration control interface.
 *    - Request major number from lanana
 */

#undef DEBUG

#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/blk-mq.h>
#include <linux/mutex.h>
#include <linux/ata.h>
#include <linux/hdreg.h>
#include <linux/platform_device.h>
#if defined(CONFIG_OF)
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#endif

MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
MODULE_DESCRIPTION("Xilinx SystemACE device driver");
MODULE_LICENSE("GPL");

/* SystemACE register definitions */
#define ACE_BUSMODE (0x00)

#define ACE_STATUS (0x04)
#define ACE_STATUS_CFGLOCK      (0x00000001)
#define ACE_STATUS_MPULOCK      (0x00000002)
#define ACE_STATUS_CFGERROR     (0x00000004)    /* config controller error */
#define ACE_STATUS_CFCERROR     (0x00000008)    /* CF controller error */
#define ACE_STATUS_CFDETECT     (0x00000010)
#define ACE_STATUS_DATABUFRDY   (0x00000020)
#define ACE_STATUS_DATABUFMODE  (0x00000040)
#define ACE_STATUS_CFGDONE      (0x00000080)
#define ACE_STATUS_RDYFORCFCMD  (0x00000100)
#define ACE_STATUS_CFGMODEPIN   (0x00000200)
#define ACE_STATUS_CFGADDR_MASK (0x0000e000)
#define ACE_STATUS_CFBSY        (0x00020000)
#define ACE_STATUS_CFRDY        (0x00040000)
#define ACE_STATUS_CFDWF        (0x00080000)
#define ACE_STATUS_CFDSC        (0x00100000)
#define ACE_STATUS_CFDRQ        (0x00200000)
#define ACE_STATUS_CFCORR       (0x00400000)
#define ACE_STATUS_CFERR        (0x00800000)

#define ACE_ERROR (0x08)
#define ACE_CFGLBA (0x0c)
#define ACE_MPULBA (0x10)

#define ACE_SECCNTCMD (0x14)
#define ACE_SECCNTCMD_RESET      (0x0100)
#define ACE_SECCNTCMD_IDENTIFY   (0x0200)
#define ACE_SECCNTCMD_READ_DATA  (0x0300)
#define ACE_SECCNTCMD_WRITE_DATA (0x0400)
#define ACE_SECCNTCMD_ABORT      (0x0600)

#define ACE_VERSION (0x16)
#define ACE_VERSION_REVISION_MASK (0x00FF)
#define ACE_VERSION_MINOR_MASK    (0x0F00)
#define ACE_VERSION_MAJOR_MASK    (0xF000)

#define ACE_CTRL (0x18)
#define ACE_CTRL_FORCELOCKREQ   (0x0001)
#define ACE_CTRL_LOCKREQ        (0x0002)
#define ACE_CTRL_FORCECFGADDR   (0x0004)
#define ACE_CTRL_FORCECFGMODE   (0x0008)
#define ACE_CTRL_CFGMODE        (0x0010)
#define ACE_CTRL_CFGSTART       (0x0020)
#define ACE_CTRL_CFGSEL         (0x0040)
#define ACE_CTRL_CFGRESET       (0x0080)
#define ACE_CTRL_DATABUFRDYIRQ  (0x0100)
#define ACE_CTRL_ERRORIRQ       (0x0200)
#define ACE_CTRL_CFGDONEIRQ     (0x0400)
#define ACE_CTRL_RESETIRQ       (0x0800)
#define ACE_CTRL_CFGPROG        (0x1000)
#define ACE_CTRL_CFGADDR_MASK   (0xe000)

#define ACE_FATSTAT (0x1c)

#define ACE_NUM_MINORS 16
#define ACE_SECTOR_SIZE (512)
#define ACE_FIFO_SIZE (32)
#define ACE_BUF_PER_SECTOR (ACE_SECTOR_SIZE / ACE_FIFO_SIZE)

#define ACE_BUS_WIDTH_8  0
#define ACE_BUS_WIDTH_16 1

struct ace_reg_ops;

struct ace_device {
        /* driver state data */
        int id;
        int media_change;
        int users;
        struct list_head list;

        /* finite state machine data */
        struct tasklet_struct fsm_tasklet;
        uint fsm_task;          /* Current activity (ACE_TASK_*) */
        uint fsm_state;         /* Current state (ACE_FSM_STATE_*) */
        uint fsm_continue_flag; /* cleared to exit FSM mainloop */
        uint fsm_iter_num;
        struct timer_list stall_timer;

        /* Transfer state/result, use for both id and block request */
        struct request *req;    /* request being processed */
        void *data_ptr;         /* pointer to I/O buffer */
        int data_count;         /* number of buffers remaining */
        int data_result;        /* Result of transfer; 0 := success */

        int id_req_count;       /* count of id requests */
        int id_result;
        struct completion id_completion;        /* used when id req finishes */
        int in_irq;

        /* Details of hardware device */
        resource_size_t physaddr;
        void __iomem *baseaddr;
        int irq;
        int bus_width;          /* 0 := 8 bit; 1 := 16 bit */
        struct ace_reg_ops *reg_ops;
        int lock_count;

        /* Block device data structures */
        spinlock_t lock;
        struct device *dev;
        struct request_queue *queue;
        struct gendisk *gd;
        struct blk_mq_tag_set tag_set;
        struct list_head rq_list;

        /* Inserted CF card parameters */
        u16 cf_id[ATA_ID_WORDS];
};

static DEFINE_MUTEX(xsysace_mutex);
static int ace_major;

/* ---------------------------------------------------------------------
 * Low level register access
 */

struct ace_reg_ops {
        u16(*in) (struct ace_device * ace, int reg);
        void (*out) (struct ace_device * ace, int reg, u16 val);
        void (*datain) (struct ace_device * ace);
        void (*dataout) (struct ace_device * ace);
};

/* 8 Bit bus width */
static u16 ace_in_8(struct ace_device *ace, int reg)
{
        void __iomem *r = ace->baseaddr + reg;
        return in_8(r) | (in_8(r + 1) << 8);
}

static void ace_out_8(struct ace_device *ace, int reg, u16 val)
{
        void __iomem *r = ace->baseaddr + reg;
        out_8(r, val);
        out_8(r + 1, val >> 8);
}

static void ace_datain_8(struct ace_device *ace)
{
        void __iomem *r = ace->baseaddr + 0x40;
        u8 *dst = ace->data_ptr;
        int i = ACE_FIFO_SIZE;
        while (i--)
                *dst++ = in_8(r++);
        ace->data_ptr = dst;
}

static void ace_dataout_8(struct ace_device *ace)
{
        void __iomem *r = ace->baseaddr + 0x40;
        u8 *src = ace->data_ptr;
        int i = ACE_FIFO_SIZE;
        while (i--)
                out_8(r++, *src++);
        ace->data_ptr = src;
}

static struct ace_reg_ops ace_reg_8_ops = {
        .in = ace_in_8,
        .out = ace_out_8,
        .datain = ace_datain_8,
        .dataout = ace_dataout_8,
};

/* 16 bit big endian bus attachment */
static u16 ace_in_be16(struct ace_device *ace, int reg)
{
        return in_be16(ace->baseaddr + reg);
}

static void ace_out_be16(struct ace_device *ace, int reg, u16 val)
{
        out_be16(ace->baseaddr + reg, val);
}

static void ace_datain_be16(struct ace_device *ace)
{
        int i = ACE_FIFO_SIZE / 2;
        u16 *dst = ace->data_ptr;
        while (i--)
                *dst++ = in_le16(ace->baseaddr + 0x40);
        ace->data_ptr = dst;
}

static void ace_dataout_be16(struct ace_device *ace)
{
        int i = ACE_FIFO_SIZE / 2;
        u16 *src = ace->data_ptr;
        while (i--)
                out_le16(ace->baseaddr + 0x40, *src++);
        ace->data_ptr = src;
}

/* 16 bit little endian bus attachment */
static u16 ace_in_le16(struct ace_device *ace, int reg)
{
        return in_le16(ace->baseaddr + reg);
}

static void ace_out_le16(struct ace_device *ace, int reg, u16 val)
{
        out_le16(ace->baseaddr + reg, val);
}

static void ace_datain_le16(struct ace_device *ace)
{
        int i = ACE_FIFO_SIZE / 2;
        u16 *dst = ace->data_ptr;
        while (i--)
                *dst++ = in_be16(ace->baseaddr + 0x40);
        ace->data_ptr = dst;
}

static void ace_dataout_le16(struct ace_device *ace)
{
        int i = ACE_FIFO_SIZE / 2;
        u16 *src = ace->data_ptr;
        while (i--)
                out_be16(ace->baseaddr + 0x40, *src++);
        ace->data_ptr = src;
}

static struct ace_reg_ops ace_reg_be16_ops = {
        .in = ace_in_be16,
        .out = ace_out_be16,
        .datain = ace_datain_be16,
        .dataout = ace_dataout_be16,
};

static struct ace_reg_ops ace_reg_le16_ops = {
        .in = ace_in_le16,
        .out = ace_out_le16,
        .datain = ace_datain_le16,
        .dataout = ace_dataout_le16,
};

static inline u16 ace_in(struct ace_device *ace, int reg)
{
        return ace->reg_ops->in(ace, reg);
}

static inline u32 ace_in32(struct ace_device *ace, int reg)
{
        return ace_in(ace, reg) | (ace_in(ace, reg + 2) << 16);
}

static inline void ace_out(struct ace_device *ace, int reg, u16 val)
{
        ace->reg_ops->out(ace, reg, val);
}

static inline void ace_out32(struct ace_device *ace, int reg, u32 val)
{
        ace_out(ace, reg, val);
        ace_out(ace, reg + 2, val >> 16);
}

/* ---------------------------------------------------------------------
 * Debug support functions
 */

#if defined(DEBUG)
static void ace_dump_mem(void *base, int len)
{
        const char *ptr = base;
        int i, j;

        for (i = 0; i < len; i += 16) {
                printk(KERN_INFO "%.8x:", i);
                for (j = 0; j < 16; j++) {
                        if (!(j % 4))
                                printk(" ");
                        printk("%.2x", ptr[i + j]);
                }
                printk(" ");
                for (j = 0; j < 16; j++)
                        printk("%c", isprint(ptr[i + j]) ? ptr[i + j] : '.');
                printk("\n");
        }
}
#else
static inline void ace_dump_mem(void *base, int len)
{
}
#endif

static void ace_dump_regs(struct ace_device *ace)
{
        dev_info(ace->dev,
                 "    ctrl:  %.8x  seccnt/cmd: %.4x      ver:%.4x\n"
                 "    status:%.8x  mpu_lba:%.8x  busmode:%4x\n"
                 "    error: %.8x  cfg_lba:%.8x  fatstat:%.4x\n",
                 ace_in32(ace, ACE_CTRL),
                 ace_in(ace, ACE_SECCNTCMD),
                 ace_in(ace, ACE_VERSION),
                 ace_in32(ace, ACE_STATUS),
                 ace_in32(ace, ACE_MPULBA),
                 ace_in(ace, ACE_BUSMODE),
                 ace_in32(ace, ACE_ERROR),
                 ace_in32(ace, ACE_CFGLBA), ace_in(ace, ACE_FATSTAT));
}

static void ace_fix_driveid(u16 *id)
{
#if defined(__BIG_ENDIAN)
        int i;

        /* All half words have wrong byte order; swap the bytes */
        for (i = 0; i < ATA_ID_WORDS; i++, id++)
                *id = le16_to_cpu(*id);
#endif
}

/* ---------------------------------------------------------------------
 * Finite State Machine (FSM) implementation
 */

/* FSM tasks; used to direct state transitions */
#define ACE_TASK_IDLE      0
#define ACE_TASK_IDENTIFY  1
#define ACE_TASK_READ      2
#define ACE_TASK_WRITE     3
#define ACE_FSM_NUM_TASKS  4

/* FSM state definitions */
#define ACE_FSM_STATE_IDLE               0
#define ACE_FSM_STATE_REQ_LOCK           1
#define ACE_FSM_STATE_WAIT_LOCK          2
#define ACE_FSM_STATE_WAIT_CFREADY       3
#define ACE_FSM_STATE_IDENTIFY_PREPARE   4
#define ACE_FSM_STATE_IDENTIFY_TRANSFER  5
#define ACE_FSM_STATE_IDENTIFY_COMPLETE  6
#define ACE_FSM_STATE_REQ_PREPARE        7
#define ACE_FSM_STATE_REQ_TRANSFER       8
#define ACE_FSM_STATE_REQ_COMPLETE       9
#define ACE_FSM_STATE_ERROR             10
#define ACE_FSM_NUM_STATES              11

/* Set flag to exit FSM loop and reschedule tasklet */
static inline void ace_fsm_yield(struct ace_device *ace)
{
        dev_dbg(ace->dev, "ace_fsm_yield()\n");
        tasklet_schedule(&ace->fsm_tasklet);
        ace->fsm_continue_flag = 0;
}

/* Set flag to exit FSM loop and wait for IRQ to reschedule tasklet */
static inline void ace_fsm_yieldirq(struct ace_device *ace)
{
        dev_dbg(ace->dev, "ace_fsm_yieldirq()\n");

        if (!ace->irq)
                /* No IRQ assigned, so need to poll */
                tasklet_schedule(&ace->fsm_tasklet);
        ace->fsm_continue_flag = 0;
}

static bool ace_has_next_request(struct request_queue *q)
{
        struct ace_device *ace = q->queuedata;

        return !list_empty(&ace->rq_list);
}

/* Get the next read/write request; ending requests that we don't handle */
static struct request *ace_get_next_request(struct request_queue *q)
{
        struct ace_device *ace = q->queuedata;
        struct request *rq;

        rq = list_first_entry_or_null(&ace->rq_list, struct request, queuelist);
        if (rq) {
                list_del_init(&rq->queuelist);
                blk_mq_start_request(rq);
        }

        return NULL;
}

static void ace_fsm_dostate(struct ace_device *ace)
{
        struct request *req;
        u32 status;
        u16 val;
        int count;

#if defined(DEBUG)
        dev_dbg(ace->dev, "fsm_state=%i, id_req_count=%i\n",
                ace->fsm_state, ace->id_req_count);
#endif

        /* Verify that there is actually a CF in the slot. If not, then
         * bail out back to the idle state and wake up all the waiters */
        status = ace_in32(ace, ACE_STATUS);
        if ((status & ACE_STATUS_CFDETECT) == 0) {
                ace->fsm_state = ACE_FSM_STATE_IDLE;
                ace->media_change = 1;
                set_capacity(ace->gd, 0);
                dev_info(ace->dev, "No CF in slot\n");

                /* Drop all in-flight and pending requests */
                if (ace->req) {
                        blk_mq_end_request(ace->req, BLK_STS_IOERR);
                        ace->req = NULL;
                }
                while ((req = ace_get_next_request(ace->queue)) != NULL)
                        blk_mq_end_request(req, BLK_STS_IOERR);

                /* Drop back to IDLE state and notify waiters */
                ace->fsm_state = ACE_FSM_STATE_IDLE;
                ace->id_result = -EIO;
                while (ace->id_req_count) {
                        complete(&ace->id_completion);
                        ace->id_req_count--;
                }
        }

        switch (ace->fsm_state) {
        case ACE_FSM_STATE_IDLE:
                /* See if there is anything to do */
                if (ace->id_req_count || ace_has_next_request(ace->queue)) {
                        ace->fsm_iter_num++;
                        ace->fsm_state = ACE_FSM_STATE_REQ_LOCK;
                        mod_timer(&ace->stall_timer, jiffies + HZ);
                        if (!timer_pending(&ace->stall_timer))
                                add_timer(&ace->stall_timer);
                        break;
                }
                del_timer(&ace->stall_timer);
                ace->fsm_continue_flag = 0;
                break;

        case ACE_FSM_STATE_REQ_LOCK:
                if (ace_in(ace, ACE_STATUS) & ACE_STATUS_MPULOCK) {
                        /* Already have the lock, jump to next state */
                        ace->fsm_state = ACE_FSM_STATE_WAIT_CFREADY;
                        break;
                }

                /* Request the lock */
                val = ace_in(ace, ACE_CTRL);
                ace_out(ace, ACE_CTRL, val | ACE_CTRL_LOCKREQ);
                ace->fsm_state = ACE_FSM_STATE_WAIT_LOCK;
                break;

        case ACE_FSM_STATE_WAIT_LOCK:
                if (ace_in(ace, ACE_STATUS) & ACE_STATUS_MPULOCK) {
                        /* got the lock; move to next state */
                        ace->fsm_state = ACE_FSM_STATE_WAIT_CFREADY;
                        break;
                }

                /* wait a bit for the lock */
                ace_fsm_yield(ace);
                break;

        case ACE_FSM_STATE_WAIT_CFREADY:
                status = ace_in32(ace, ACE_STATUS);
                if (!(status & ACE_STATUS_RDYFORCFCMD) ||
                    (status & ACE_STATUS_CFBSY)) {
                        /* CF card isn't ready; it needs to be polled */
                        ace_fsm_yield(ace);
                        break;
                }

                /* Device is ready for command; determine what to do next */
                if (ace->id_req_count)
                        ace->fsm_state = ACE_FSM_STATE_IDENTIFY_PREPARE;
                else
                        ace->fsm_state = ACE_FSM_STATE_REQ_PREPARE;
                break;

        case ACE_FSM_STATE_IDENTIFY_PREPARE:
                /* Send identify command */
                ace->fsm_task = ACE_TASK_IDENTIFY;
                ace->data_ptr = ace->cf_id;
                ace->data_count = ACE_BUF_PER_SECTOR;
                ace_out(ace, ACE_SECCNTCMD, ACE_SECCNTCMD_IDENTIFY);

                /* As per datasheet, put config controller in reset */
                val = ace_in(ace, ACE_CTRL);
                ace_out(ace, ACE_CTRL, val | ACE_CTRL_CFGRESET);

                /* irq handler takes over from this point; wait for the
                 * transfer to complete */
                ace->fsm_state = ACE_FSM_STATE_IDENTIFY_TRANSFER;
                ace_fsm_yieldirq(ace);
                break;

        case ACE_FSM_STATE_IDENTIFY_TRANSFER:
                /* Check that the sysace is ready to receive data */
                status = ace_in32(ace, ACE_STATUS);
                if (status & ACE_STATUS_CFBSY) {
                        dev_dbg(ace->dev, "CFBSY set; t=%i iter=%i dc=%i\n",
                                ace->fsm_task, ace->fsm_iter_num,
                                ace->data_count);
                        ace_fsm_yield(ace);
                        break;
                }
                if (!(status & ACE_STATUS_DATABUFRDY)) {
                        ace_fsm_yield(ace);
                        break;
                }

                /* Transfer the next buffer */
                ace->reg_ops->datain(ace);
                ace->data_count--;

                /* If there are still buffers to be transfers; jump out here */
                if (ace->data_count != 0) {
                        ace_fsm_yieldirq(ace);
                        break;
                }

                /* transfer finished; kick state machine */
                dev_dbg(ace->dev, "identify finished\n");
                ace->fsm_state = ACE_FSM_STATE_IDENTIFY_COMPLETE;
                break;

        case ACE_FSM_STATE_IDENTIFY_COMPLETE:
                ace_fix_driveid(ace->cf_id);
                ace_dump_mem(ace->cf_id, 512);  /* Debug: Dump out disk ID */

                if (ace->data_result) {
                        /* Error occurred, disable the disk */
                        ace->media_change = 1;
                        set_capacity(ace->gd, 0);
                        dev_err(ace->dev, "error fetching CF id (%i)\n",
                                ace->data_result);
                } else {
                        ace->media_change = 0;

                        /* Record disk parameters */
                        set_capacity(ace->gd,
                                ata_id_u32(ace->cf_id, ATA_ID_LBA_CAPACITY));
                        dev_info(ace->dev, "capacity: %i sectors\n",
                                ata_id_u32(ace->cf_id, ATA_ID_LBA_CAPACITY));
                }

                /* We're done, drop to IDLE state and notify waiters */
                ace->fsm_state = ACE_FSM_STATE_IDLE;
                ace->id_result = ace->data_result;
                while (ace->id_req_count) {
                        complete(&ace->id_completion);
                        ace->id_req_count--;
                }
                break;

        case ACE_FSM_STATE_REQ_PREPARE:
                req = ace_get_next_request(ace->queue);
                if (!req) {
                        ace->fsm_state = ACE_FSM_STATE_IDLE;
                        break;
                }

                /* Okay, it's a data request, set it up for transfer */
                dev_dbg(ace->dev,
                        "request: sec=%llx hcnt=%x, ccnt=%x, dir=%i\n",
                        (unsigned long long)blk_rq_pos(req),
                        blk_rq_sectors(req), blk_rq_cur_sectors(req),
                        rq_data_dir(req));

                ace->req = req;
                ace->data_ptr = bio_data(req->bio);
                ace->data_count = blk_rq_cur_sectors(req) * ACE_BUF_PER_SECTOR;
                ace_out32(ace, ACE_MPULBA, blk_rq_pos(req) & 0x0FFFFFFF);

                count = blk_rq_sectors(req);
                if (rq_data_dir(req)) {
                        /* Kick off write request */
                        dev_dbg(ace->dev, "write data\n");
                        ace->fsm_task = ACE_TASK_WRITE;
                        ace_out(ace, ACE_SECCNTCMD,
                                count | ACE_SECCNTCMD_WRITE_DATA);
                } else {
                        /* Kick off read request */
                        dev_dbg(ace->dev, "read data\n");
                        ace->fsm_task = ACE_TASK_READ;
                        ace_out(ace, ACE_SECCNTCMD,
                                count | ACE_SECCNTCMD_READ_DATA);
                }

                /* As per datasheet, put config controller in reset */
                val = ace_in(ace, ACE_CTRL);
                ace_out(ace, ACE_CTRL, val | ACE_CTRL_CFGRESET);

                /* Move to the transfer state.  The systemace will raise
                 * an interrupt once there is something to do
                 */
                ace->fsm_state = ACE_FSM_STATE_REQ_TRANSFER;
                if (ace->fsm_task == ACE_TASK_READ)
                        ace_fsm_yieldirq(ace);  /* wait for data ready */
                break;

        case ACE_FSM_STATE_REQ_TRANSFER:
                /* Check that the sysace is ready to receive data */
                status = ace_in32(ace, ACE_STATUS);
                if (status & ACE_STATUS_CFBSY) {
                        dev_dbg(ace->dev,
                                "CFBSY set; t=%i iter=%i c=%i dc=%i irq=%i\n",
                                ace->fsm_task, ace->fsm_iter_num,
                                blk_rq_cur_sectors(ace->req) * 16,
                                ace->data_count, ace->in_irq);
                        ace_fsm_yield(ace);     /* need to poll CFBSY bit */
                        break;
                }
                if (!(status & ACE_STATUS_DATABUFRDY)) {
                        dev_dbg(ace->dev,
                                "DATABUF not set; t=%i iter=%i c=%i dc=%i irq=%i\n",
                                ace->fsm_task, ace->fsm_iter_num,
                                blk_rq_cur_sectors(ace->req) * 16,
                                ace->data_count, ace->in_irq);
                        ace_fsm_yieldirq(ace);
                        break;
                }

                /* Transfer the next buffer */
                if (ace->fsm_task == ACE_TASK_WRITE)
                        ace->reg_ops->dataout(ace);
                else
                        ace->reg_ops->datain(ace);
                ace->data_count--;

                /* If there are still buffers to be transfers; jump out here */
                if (ace->data_count != 0) {
                        ace_fsm_yieldirq(ace);
                        break;
                }

                /* bio finished; is there another one? */
                if (blk_update_request(ace->req, BLK_STS_OK,
                    blk_rq_cur_bytes(ace->req))) {
                        /* dev_dbg(ace->dev, "next block; h=%u c=%u\n",
                         *      blk_rq_sectors(ace->req),
                         *      blk_rq_cur_sectors(ace->req));
                         */
                        ace->data_ptr = bio_data(ace->req->bio);
                        ace->data_count = blk_rq_cur_sectors(ace->req) * 16;
                        ace_fsm_yieldirq(ace);
                        break;
                }

                ace->fsm_state = ACE_FSM_STATE_REQ_COMPLETE;
                break;

        case ACE_FSM_STATE_REQ_COMPLETE:
                ace->req = NULL;

                /* Finished request; go to idle state */
                ace->fsm_state = ACE_FSM_STATE_IDLE;
                break;

        default:
                ace->fsm_state = ACE_FSM_STATE_IDLE;
                break;
        }
}

static void ace_fsm_tasklet(unsigned long data)
{
        struct ace_device *ace = (void *)data;
        unsigned long flags;

        spin_lock_irqsave(&ace->lock, flags);

        /* Loop over state machine until told to stop */
        ace->fsm_continue_flag = 1;
        while (ace->fsm_continue_flag)
                ace_fsm_dostate(ace);

        spin_unlock_irqrestore(&ace->lock, flags);
}

static void ace_stall_timer(struct timer_list *t)
{
        struct ace_device *ace = from_timer(ace, t, stall_timer);
        unsigned long flags;

        dev_warn(ace->dev,
                 "kicking stalled fsm; state=%i task=%i iter=%i dc=%i\n",
                 ace->fsm_state, ace->fsm_task, ace->fsm_iter_num,
                 ace->data_count);
        spin_lock_irqsave(&ace->lock, flags);

        /* Rearm the stall timer *before* entering FSM (which may then
         * delete the timer) */
        mod_timer(&ace->stall_timer, jiffies + HZ);

        /* Loop over state machine until told to stop */
        ace->fsm_continue_flag = 1;
        while (ace->fsm_continue_flag)
                ace_fsm_dostate(ace);

        spin_unlock_irqrestore(&ace->lock, flags);
}

/* ---------------------------------------------------------------------
 * Interrupt handling routines
 */
static int ace_interrupt_checkstate(struct ace_device *ace)
{
        u32 sreg = ace_in32(ace, ACE_STATUS);
        u16 creg = ace_in(ace, ACE_CTRL);

        /* Check for error occurrence */
        if ((sreg & (ACE_STATUS_CFGERROR | ACE_STATUS_CFCERROR)) &&
            (creg & ACE_CTRL_ERRORIRQ)) {
                dev_err(ace->dev, "transfer failure\n");
                ace_dump_regs(ace);
                return -EIO;
        }

        return 0;
}

static irqreturn_t ace_interrupt(int irq, void *dev_id)
{
        u16 creg;
        struct ace_device *ace = dev_id;

        /* be safe and get the lock */
        spin_lock(&ace->lock);
        ace->in_irq = 1;

        /* clear the interrupt */
        creg = ace_in(ace, ACE_CTRL);
        ace_out(ace, ACE_CTRL, creg | ACE_CTRL_RESETIRQ);
        ace_out(ace, ACE_CTRL, creg);

        /* check for IO failures */
        if (ace_interrupt_checkstate(ace))
                ace->data_result = -EIO;

        if (ace->fsm_task == 0) {
                dev_err(ace->dev,
                        "spurious irq; stat=%.8x ctrl=%.8x cmd=%.4x\n",
                        ace_in32(ace, ACE_STATUS), ace_in32(ace, ACE_CTRL),
                        ace_in(ace, ACE_SECCNTCMD));
                dev_err(ace->dev, "fsm_task=%i fsm_state=%i data_count=%i\n",
                        ace->fsm_task, ace->fsm_state, ace->data_count);
        }

        /* Loop over state machine until told to stop */
        ace->fsm_continue_flag = 1;
        while (ace->fsm_continue_flag)
                ace_fsm_dostate(ace);

        /* done with interrupt; drop the lock */
        ace->in_irq = 0;
        spin_unlock(&ace->lock);

        return IRQ_HANDLED;
}

/* ---------------------------------------------------------------------
 * Block ops
 */
static blk_status_t ace_queue_rq(struct blk_mq_hw_ctx *hctx,
                                 const struct blk_mq_queue_data *bd)
{
        struct ace_device *ace = hctx->queue->queuedata;
        struct request *req = bd->rq;

        if (blk_rq_is_passthrough(req)) {
                blk_mq_start_request(req);
                return BLK_STS_IOERR;
        }

        spin_lock_irq(&ace->lock);
        list_add_tail(&req->queuelist, &ace->rq_list);
        spin_unlock_irq(&ace->lock);

        tasklet_schedule(&ace->fsm_tasklet);
        return BLK_STS_OK;
}

static unsigned int ace_check_events(struct gendisk *gd, unsigned int clearing)
{
        struct ace_device *ace = gd->private_data;
        dev_dbg(ace->dev, "ace_check_events(): %i\n", ace->media_change);

        return ace->media_change ? DISK_EVENT_MEDIA_CHANGE : 0;
}

static int ace_revalidate_disk(struct gendisk *gd)
{
        struct ace_device *ace = gd->private_data;
        unsigned long flags;

        dev_dbg(ace->dev, "ace_revalidate_disk()\n");

        if (ace->media_change) {
                dev_dbg(ace->dev, "requesting cf id and scheduling tasklet\n");

                spin_lock_irqsave(&ace->lock, flags);
                ace->id_req_count++;
                spin_unlock_irqrestore(&ace->lock, flags);

                tasklet_schedule(&ace->fsm_tasklet);
                wait_for_completion(&ace->id_completion);
        }

        dev_dbg(ace->dev, "revalidate complete\n");
        return ace->id_result;
}

static int ace_open(struct block_device *bdev, fmode_t mode)
{
        struct ace_device *ace = bdev->bd_disk->private_data;
        unsigned long flags;

        dev_dbg(ace->dev, "ace_open() users=%i\n", ace->users + 1);

        mutex_lock(&xsysace_mutex);
        spin_lock_irqsave(&ace->lock, flags);
        ace->users++;
        spin_unlock_irqrestore(&ace->lock, flags);

        check_disk_change(bdev);
        mutex_unlock(&xsysace_mutex);

        return 0;
}

static void ace_release(struct gendisk *disk, fmode_t mode)
{
        struct ace_device *ace = disk->private_data;
        unsigned long flags;
        u16 val;

        dev_dbg(ace->dev, "ace_release() users=%i\n", ace->users - 1);

        mutex_lock(&xsysace_mutex);
        spin_lock_irqsave(&ace->lock, flags);
        ace->users--;
        if (ace->users == 0) {
                val = ace_in(ace, ACE_CTRL);
                ace_out(ace, ACE_CTRL, val & ~ACE_CTRL_LOCKREQ);
        }
        spin_unlock_irqrestore(&ace->lock, flags);
        mutex_unlock(&xsysace_mutex);
}

static int ace_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        struct ace_device *ace = bdev->bd_disk->private_data;
        u16 *cf_id = ace->cf_id;

        dev_dbg(ace->dev, "ace_getgeo()\n");

        geo->heads      = cf_id[ATA_ID_HEADS];
        geo->sectors    = cf_id[ATA_ID_SECTORS];
        geo->cylinders  = cf_id[ATA_ID_CYLS];

        return 0;
}

static const struct block_device_operations ace_fops = {
        .owner = THIS_MODULE,
        .open = ace_open,
        .release = ace_release,
        .check_events = ace_check_events,
        .revalidate_disk = ace_revalidate_disk,
        .getgeo = ace_getgeo,
};

static const struct blk_mq_ops ace_mq_ops = {
        .queue_rq       = ace_queue_rq,
};

/* --------------------------------------------------------------------
 * SystemACE device setup/teardown code
 */
static int ace_setup(struct ace_device *ace)
{
        u16 version;
        u16 val;
        int rc;

        dev_dbg(ace->dev, "ace_setup(ace=0x%p)\n", ace);
        dev_dbg(ace->dev, "physaddr=0x%llx irq=%i\n",
                (unsigned long long)ace->physaddr, ace->irq);

        spin_lock_init(&ace->lock);
        init_completion(&ace->id_completion);
        INIT_LIST_HEAD(&ace->rq_list);

        /*
         * Map the device
         */
        ace->baseaddr = ioremap(ace->physaddr, 0x80);
        if (!ace->baseaddr)
                goto err_ioremap;

        /*
         * Initialize the state machine tasklet and stall timer
         */
        tasklet_init(&ace->fsm_tasklet, ace_fsm_tasklet, (unsigned long)ace);
        timer_setup(&ace->stall_timer, ace_stall_timer, 0);

        /*
         * Initialize the request queue
         */
        ace->queue = blk_mq_init_sq_queue(&ace->tag_set, &ace_mq_ops, 2,
                                                BLK_MQ_F_SHOULD_MERGE);
        if (IS_ERR(ace->queue)) {
                rc = PTR_ERR(ace->queue);
                ace->queue = NULL;
                goto err_blk_initq;
        }
        ace->queue->queuedata = ace;

        blk_queue_logical_block_size(ace->queue, 512);
        blk_queue_bounce_limit(ace->queue, BLK_BOUNCE_HIGH);

        /*
         * Allocate and initialize GD structure
         */
        ace->gd = alloc_disk(ACE_NUM_MINORS);
        if (!ace->gd)
                goto err_alloc_disk;

        ace->gd->major = ace_major;
        ace->gd->first_minor = ace->id * ACE_NUM_MINORS;
        ace->gd->fops = &ace_fops;
        ace->gd->events = DISK_EVENT_MEDIA_CHANGE;
        ace->gd->queue = ace->queue;
        ace->gd->private_data = ace;
        snprintf(ace->gd->disk_name, 32, "xs%c", ace->id + 'a');

        /* set bus width */
        if (ace->bus_width == ACE_BUS_WIDTH_16) {
                /* 0x0101 should work regardless of endianess */
                ace_out_le16(ace, ACE_BUSMODE, 0x0101);

                /* read it back to determine endianess */
                if (ace_in_le16(ace, ACE_BUSMODE) == 0x0001)
                        ace->reg_ops = &ace_reg_le16_ops;
                else
                        ace->reg_ops = &ace_reg_be16_ops;
        } else {
                ace_out_8(ace, ACE_BUSMODE, 0x00);
                ace->reg_ops = &ace_reg_8_ops;
        }

        /* Make sure version register is sane */
        version = ace_in(ace, ACE_VERSION);
        if ((version == 0) || (version == 0xFFFF))
                goto err_read;

        /* Put sysace in a sane state by clearing most control reg bits */
        ace_out(ace, ACE_CTRL, ACE_CTRL_FORCECFGMODE |
                ACE_CTRL_DATABUFRDYIRQ | ACE_CTRL_ERRORIRQ);

        /* Now we can hook up the irq handler */
        if (ace->irq) {
                rc = request_irq(ace->irq, ace_interrupt, 0, "systemace", ace);
                if (rc) {
                        /* Failure - fall back to polled mode */
                        dev_err(ace->dev, "request_irq failed\n");
                        ace->irq = 0;
                }
        }

        /* Enable interrupts */
        val = ace_in(ace, ACE_CTRL);
        val |= ACE_CTRL_DATABUFRDYIRQ | ACE_CTRL_ERRORIRQ;
        ace_out(ace, ACE_CTRL, val);

        /* Print the identification */
        dev_info(ace->dev, "Xilinx SystemACE revision %i.%i.%i\n",
                 (version >> 12) & 0xf, (version >> 8) & 0x0f, version & 0xff);
        dev_dbg(ace->dev, "physaddr 0x%llx, mapped to 0x%p, irq=%i\n",
                (unsigned long long) ace->physaddr, ace->baseaddr, ace->irq);

        ace->media_change = 1;
        ace_revalidate_disk(ace->gd);

        /* Make the sysace device 'live' */
        add_disk(ace->gd);

        return 0;

err_read:
        /* prevent double queue cleanup */
        ace->gd->queue = NULL;
        put_disk(ace->gd);
err_alloc_disk:
        blk_cleanup_queue(ace->queue);
        blk_mq_free_tag_set(&ace->tag_set);
err_blk_initq:
        iounmap(ace->baseaddr);
err_ioremap:
        dev_info(ace->dev, "xsysace: error initializing device at 0x%llx\n",
                 (unsigned long long) ace->physaddr);
        return -ENOMEM;
}

static void ace_teardown(struct ace_device *ace)
{
        if (ace->gd) {
                del_gendisk(ace->gd);
                put_disk(ace->gd);
        }

        if (ace->queue) {
                blk_cleanup_queue(ace->queue);
                blk_mq_free_tag_set(&ace->tag_set);
        }

        tasklet_kill(&ace->fsm_tasklet);

        if (ace->irq)
                free_irq(ace->irq, ace);

        iounmap(ace->baseaddr);
}

static int ace_alloc(struct device *dev, int id, resource_size_t physaddr,
                     int irq, int bus_width)
{
        struct ace_device *ace;
        int rc;
        dev_dbg(dev, "ace_alloc(%p)\n", dev);

        if (!physaddr) {
                rc = -ENODEV;
                goto err_noreg;
        }

        /* Allocate and initialize the ace device structure */
        ace = kzalloc(sizeof(struct ace_device), GFP_KERNEL);
        if (!ace) {
                rc = -ENOMEM;
                goto err_alloc;
        }

        ace->dev = dev;
        ace->id = id;
        ace->physaddr = physaddr;
        ace->irq = irq;
        ace->bus_width = bus_width;

        /* Call the setup code */
        rc = ace_setup(ace);
        if (rc)
                goto err_setup;

        dev_set_drvdata(dev, ace);
        return 0;

err_setup:
        dev_set_drvdata(dev, NULL);
        kfree(ace);
err_alloc:
err_noreg:
        dev_err(dev, "could not initialize device, err=%i\n", rc);
        return rc;
}

static void ace_free(struct device *dev)
{
        struct ace_device *ace = dev_get_drvdata(dev);
        dev_dbg(dev, "ace_free(%p)\n", dev);

        if (ace) {
                ace_teardown(ace);
                dev_set_drvdata(dev, NULL);
                kfree(ace);
        }
}

/* ---------------------------------------------------------------------
 * Platform Bus Support
 */

static int ace_probe(struct platform_device *dev)
{
        resource_size_t physaddr = 0;
        int bus_width = ACE_BUS_WIDTH_16; /* FIXME: should not be hard coded */
        u32 id = dev->id;
        int irq = 0;
        int i;

        dev_dbg(&dev->dev, "ace_probe(%p)\n", dev);

        /* device id and bus width */
        if (of_property_read_u32(dev->dev.of_node, "port-number", &id))
                id = 0;
        if (of_find_property(dev->dev.of_node, "8-bit", NULL))
                bus_width = ACE_BUS_WIDTH_8;

        for (i = 0; i < dev->num_resources; i++) {
                if (dev->resource[i].flags & IORESOURCE_MEM)
                        physaddr = dev->resource[i].start;
                if (dev->resource[i].flags & IORESOURCE_IRQ)
                        irq = dev->resource[i].start;
        }

        /* Call the bus-independent setup code */
        return ace_alloc(&dev->dev, id, physaddr, irq, bus_width);
}

/*
 * Platform bus remove() method
 */
static int ace_remove(struct platform_device *dev)
{
        ace_free(&dev->dev);
        return 0;
}

#if defined(CONFIG_OF)
/* Match table for of_platform binding */
static const struct of_device_id ace_of_match[] = {
        { .compatible = "xlnx,opb-sysace-1.00.b", },
        { .compatible = "xlnx,opb-sysace-1.00.c", },
        { .compatible = "xlnx,xps-sysace-1.00.a", },
        { .compatible = "xlnx,sysace", },
        {},
};
MODULE_DEVICE_TABLE(of, ace_of_match);
#else /* CONFIG_OF */
#define ace_of_match NULL
#endif /* CONFIG_OF */

static struct platform_driver ace_platform_driver = {
        .probe = ace_probe,
        .remove = ace_remove,
        .driver = {
                .name = "xsysace",
                .of_match_table = ace_of_match,
        },
};

/* ---------------------------------------------------------------------
 * Module init/exit routines
 */
static int __init ace_init(void)
{
        int rc;

        ace_major = register_blkdev(ace_major, "xsysace");
        if (ace_major <= 0) {
                rc = -ENOMEM;
                goto err_blk;
        }

        rc = platform_driver_register(&ace_platform_driver);
        if (rc)
                goto err_plat;

        pr_info("Xilinx SystemACE device driver, major=%i\n", ace_major);
        return 0;

err_plat:
        unregister_blkdev(ace_major, "xsysace");
err_blk:
        printk(KERN_ERR "xsysace: registration failed; err=%i\n", rc);
        return rc;
}
module_init(ace_init);

static void __exit ace_exit(void)
{
        pr_debug("Unregistering Xilinx SystemACE driver\n");
        platform_driver_unregister(&ace_platform_driver);
        unregister_blkdev(ace_major, "xsysace");
}
module_exit(ace_exit);