/*****************************************************************************
 *
 *     Author: Xilinx, Inc.
 *
 *     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.
 *
 *     XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS"
 *     AS A COURTESY TO YOU, SOLELY FOR USE IN DEVELOPING PROGRAMS AND
 *     SOLUTIONS FOR XILINX DEVICES.  BY PROVIDING THIS DESIGN, CODE,
 *     OR INFORMATION AS ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE,
 *     APPLICATION OR STANDARD, XILINX IS MAKING NO REPRESENTATION
 *     THAT THIS IMPLEMENTATION IS FREE FROM ANY CLAIMS OF INFRINGEMENT,
 *     AND YOU ARE RESPONSIBLE FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE
 *     FOR YOUR IMPLEMENTATION.  XILINX EXPRESSLY DISCLAIMS ANY
 *     WARRANTY WHATSOEVER WITH RESPECT TO THE ADEQUACY OF THE
 *     IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OR
 *     REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE FROM CLAIMS OF
 *     INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *     FOR A PARTICULAR PURPOSE.
 *
 *     (c) Copyright 2002 Xilinx Inc., Systems Engineering Group
 *     (c) Copyright 2004 Xilinx Inc., Systems Engineering Group
 *     (c) Copyright 2007-2008 Xilinx Inc.
 *     All rights reserved.
 *
 *     You should have received a copy of the GNU General Public License along
 *     with this program; if not, write to the Free Software Foundation, Inc.,
 *     675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *****************************************************************************/

/*
 * This is the code behind /dev/icap* -- it allows a user-space
 * application to use the Xilinx ICAP subsystem.
 *
 * The following operations are possible:
 *
 * open         open the port and initialize for access.
 * release      release port
 * write        Write a bitstream to the configuration processor.
 * read         Read a data stream from the configuration processor.
 *
 * After being opened, the port is initialized and accessed to avoid a
 * corrupted first read which may occur with some hardware.  The port
 * is left in a desynched state, requiring that a synch sequence be
 * transmitted before any valid configuration data.  A user will have
 * exclusive access to the device while it remains open, and the state
 * of the ICAP cannot be guaranteed after the device is closed.  Note
 * that a complete reset of the core and the state of the ICAP cannot
 * be performed on many versions of the cores, hence users of this
 * device should avoid making inconsistent accesses to the device.  In
 * particular, accessing the read interface, without first generating
 * a write containing a readback packet can leave the ICAP in an
 * inaccessible state.
 *
 * Note that in order to use the read interface, it is first necessary
 * to write a request packet to the write interface.  i.e., it is not
 * possible to simply readback the bitstream (or any configuration
 * bits) from a device without specifically requesting them first.
 * The code to craft such packets is intended to be part of the
 * user-space application code that uses this device.  The simplest
 * way to use this interface is simply:
 *
 * cp foo.bit /dev/icap0
 *
 * Note that unless foo.bit is an appropriately constructed partial
 * bitstream, this has a high likelihood of overwriting the design
 * currently programmed in the FPGA.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/sysctl.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#include "xilinx_hwicap.h"
#include "buffer_icap.h"
#include "fifo_icap.h"

#define DRIVER_NAME "icap"

#define HWICAP_REGS   (0x10000)

#define XHWICAP_MAJOR 259
#define XHWICAP_MINOR 0
#define HWICAP_DEVICES 1

/* An array, which is set to true when the device is registered. */
static DEFINE_MUTEX(hwicap_mutex);
static bool probed_devices[HWICAP_DEVICES];
static struct mutex icap_sem;

static const struct class icap_class = {
        .name = "xilinx_config",
};

#define UNIMPLEMENTED 0xFFFF

static const struct config_registers v2_config_registers = {
        .CRC = 0,
        .FAR = 1,
        .FDRI = 2,
        .FDRO = 3,
        .CMD = 4,
        .CTL = 5,
        .MASK = 6,
        .STAT = 7,
        .LOUT = 8,
        .COR = 9,
        .MFWR = 10,
        .FLR = 11,
        .KEY = 12,
        .CBC = 13,
        .IDCODE = 14,
        .AXSS = UNIMPLEMENTED,
        .C0R_1 = UNIMPLEMENTED,
        .CSOB = UNIMPLEMENTED,
        .WBSTAR = UNIMPLEMENTED,
        .TIMER = UNIMPLEMENTED,
        .BOOTSTS = UNIMPLEMENTED,
        .CTL_1 = UNIMPLEMENTED,
};

static const struct config_registers v4_config_registers = {
        .CRC = 0,
        .FAR = 1,
        .FDRI = 2,
        .FDRO = 3,
        .CMD = 4,
        .CTL = 5,
        .MASK = 6,
        .STAT = 7,
        .LOUT = 8,
        .COR = 9,
        .MFWR = 10,
        .FLR = UNIMPLEMENTED,
        .KEY = UNIMPLEMENTED,
        .CBC = 11,
        .IDCODE = 12,
        .AXSS = 13,
        .C0R_1 = UNIMPLEMENTED,
        .CSOB = UNIMPLEMENTED,
        .WBSTAR = UNIMPLEMENTED,
        .TIMER = UNIMPLEMENTED,
        .BOOTSTS = UNIMPLEMENTED,
        .CTL_1 = UNIMPLEMENTED,
};

static const struct config_registers v5_config_registers = {
        .CRC = 0,
        .FAR = 1,
        .FDRI = 2,
        .FDRO = 3,
        .CMD = 4,
        .CTL = 5,
        .MASK = 6,
        .STAT = 7,
        .LOUT = 8,
        .COR = 9,
        .MFWR = 10,
        .FLR = UNIMPLEMENTED,
        .KEY = UNIMPLEMENTED,
        .CBC = 11,
        .IDCODE = 12,
        .AXSS = 13,
        .C0R_1 = 14,
        .CSOB = 15,
        .WBSTAR = 16,
        .TIMER = 17,
        .BOOTSTS = 18,
        .CTL_1 = 19,
};

static const struct config_registers v6_config_registers = {
        .CRC = 0,
        .FAR = 1,
        .FDRI = 2,
        .FDRO = 3,
        .CMD = 4,
        .CTL = 5,
        .MASK = 6,
        .STAT = 7,
        .LOUT = 8,
        .COR = 9,
        .MFWR = 10,
        .FLR = UNIMPLEMENTED,
        .KEY = UNIMPLEMENTED,
        .CBC = 11,
        .IDCODE = 12,
        .AXSS = 13,
        .C0R_1 = 14,
        .CSOB = 15,
        .WBSTAR = 16,
        .TIMER = 17,
        .BOOTSTS = 22,
        .CTL_1 = 24,
};

/**
 * hwicap_command_desync - Send a DESYNC command to the ICAP port.
 * @drvdata: a pointer to the drvdata.
 *
 * Returns: '0' on success and failure value on error
 *
 * This command desynchronizes the ICAP After this command, a
 * bitstream containing a NULL packet, followed by a SYNCH packet is
 * required before the ICAP will recognize commands.
 */
static int hwicap_command_desync(struct hwicap_drvdata *drvdata)
{
        u32 buffer[4];
        u32 index = 0;

        /*
         * Create the data to be written to the ICAP.
         */
        buffer[index++] = hwicap_type_1_write(drvdata->config_regs->CMD) | 1;
        buffer[index++] = XHI_CMD_DESYNCH;
        buffer[index++] = XHI_NOOP_PACKET;
        buffer[index++] = XHI_NOOP_PACKET;

        /*
         * Write the data to the FIFO and initiate the transfer of data present
         * in the FIFO to the ICAP device.
         */
        return drvdata->config->set_configuration(drvdata,
                        &buffer[0], index);
}

/**
 * hwicap_get_configuration_register - Query a configuration register.
 * @drvdata: a pointer to the drvdata.
 * @reg: a constant which represents the configuration
 * register value to be returned.
 * Examples: XHI_IDCODE, XHI_FLR.
 * @reg_data: returns the value of the register.
 *
 * Returns: '0' on success and failure value on error
 *
 * Sends a query packet to the ICAP and then receives the response.
 * The icap is left in Synched state.
 */
static int hwicap_get_configuration_register(struct hwicap_drvdata *drvdata,
                u32 reg, u32 *reg_data)
{
        int status;
        u32 buffer[6];
        u32 index = 0;

        /*
         * Create the data to be written to the ICAP.
         */
        buffer[index++] = XHI_DUMMY_PACKET;
        buffer[index++] = XHI_NOOP_PACKET;
        buffer[index++] = XHI_SYNC_PACKET;
        buffer[index++] = XHI_NOOP_PACKET;
        buffer[index++] = XHI_NOOP_PACKET;

        /*
         * Write the data to the FIFO and initiate the transfer of data present
         * in the FIFO to the ICAP device.
         */
        status = drvdata->config->set_configuration(drvdata,
                                                    &buffer[0], index);
        if (status)
                return status;

        /* If the syncword was not found, then we need to start over. */
        status = drvdata->config->get_status(drvdata);
        if ((status & XHI_SR_DALIGN_MASK) != XHI_SR_DALIGN_MASK)
                return -EIO;

        index = 0;
        buffer[index++] = hwicap_type_1_read(reg) | 1;
        buffer[index++] = XHI_NOOP_PACKET;
        buffer[index++] = XHI_NOOP_PACKET;

        /*
         * Write the data to the FIFO and initiate the transfer of data present
         * in the FIFO to the ICAP device.
         */
        status = drvdata->config->set_configuration(drvdata,
                        &buffer[0], index);
        if (status)
                return status;

        /*
         * Read the configuration register
         */
        status = drvdata->config->get_configuration(drvdata, reg_data, 1);
        if (status)
                return status;

        return 0;
}

static int hwicap_initialize_hwicap(struct hwicap_drvdata *drvdata)
{
        int status;
        u32 idcode;

        dev_dbg(drvdata->dev, "initializing\n");

        /* Abort any current transaction, to make sure we have the
         * ICAP in a good state.
         */
        dev_dbg(drvdata->dev, "Reset...\n");
        drvdata->config->reset(drvdata);

        dev_dbg(drvdata->dev, "Desync...\n");
        status = hwicap_command_desync(drvdata);
        if (status)
                return status;

        /* Attempt to read the IDCODE from ICAP.  This
         * may not be returned correctly, due to the design of the
         * hardware.
         */
        dev_dbg(drvdata->dev, "Reading IDCODE...\n");
        status = hwicap_get_configuration_register(
                        drvdata, drvdata->config_regs->IDCODE, &idcode);
        dev_dbg(drvdata->dev, "IDCODE = %x\n", idcode);
        if (status)
                return status;

        dev_dbg(drvdata->dev, "Desync...\n");
        status = hwicap_command_desync(drvdata);
        if (status)
                return status;

        return 0;
}

static ssize_t
hwicap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
        struct hwicap_drvdata *drvdata = file->private_data;
        ssize_t bytes_to_read = 0;
        u32 *kbuf;
        u32 words;
        u32 bytes_remaining;
        int status;

        status = mutex_lock_interruptible(&drvdata->sem);
        if (status)
                return status;

        if (drvdata->read_buffer_in_use) {
                /* If there are leftover bytes in the buffer, just */
                /* return them and don't try to read more from the */
                /* ICAP device. */
                bytes_to_read =
                        (count < drvdata->read_buffer_in_use) ? count :
                        drvdata->read_buffer_in_use;

                /* Return the data currently in the read buffer. */
                if (copy_to_user(buf, drvdata->read_buffer, bytes_to_read)) {
                        status = -EFAULT;
                        goto error;
                }
                drvdata->read_buffer_in_use -= bytes_to_read;
                memmove(drvdata->read_buffer,
                       drvdata->read_buffer + bytes_to_read,
                       4 - bytes_to_read);
        } else {
                /* Get new data from the ICAP, and return what was requested. */
                kbuf = (u32 *) get_zeroed_page(GFP_KERNEL);
                if (!kbuf) {
                        status = -ENOMEM;
                        goto error;
                }

                /* The ICAP device is only able to read complete */
                /* words.  If a number of bytes that do not correspond */
                /* to complete words is requested, then we read enough */
                /* words to get the required number of bytes, and then */
                /* save the remaining bytes for the next read. */

                /* Determine the number of words to read, rounding up */
                /* if necessary. */
                words = ((count + 3) >> 2);
                bytes_to_read = words << 2;

                if (bytes_to_read > PAGE_SIZE)
                        bytes_to_read = PAGE_SIZE;

                /* Ensure we only read a complete number of words. */
                bytes_remaining = bytes_to_read & 3;
                bytes_to_read &= ~3;
                words = bytes_to_read >> 2;

                status = drvdata->config->get_configuration(drvdata,
                                kbuf, words);

                /* If we didn't read correctly, then bail out. */
                if (status) {
                        free_page((unsigned long)kbuf);
                        goto error;
                }

                /* If we fail to return the data to the user, then bail out. */
                if (copy_to_user(buf, kbuf, bytes_to_read)) {
                        free_page((unsigned long)kbuf);
                        status = -EFAULT;
                        goto error;
                }
                memcpy(drvdata->read_buffer,
                       kbuf,
                       bytes_remaining);
                drvdata->read_buffer_in_use = bytes_remaining;
                free_page((unsigned long)kbuf);
        }
        status = bytes_to_read;
 error:
        mutex_unlock(&drvdata->sem);
        return status;
}

static ssize_t
hwicap_write(struct file *file, const char __user *buf,
                size_t count, loff_t *ppos)
{
        struct hwicap_drvdata *drvdata = file->private_data;
        ssize_t written = 0;
        ssize_t left = count;
        u32 *kbuf;
        ssize_t len;
        ssize_t status;

        status = mutex_lock_interruptible(&drvdata->sem);
        if (status)
                return status;

        left += drvdata->write_buffer_in_use;

        /* Only write multiples of 4 bytes. */
        if (left < 4) {
                status = 0;
                goto error;
        }

        kbuf = (u32 *) __get_free_page(GFP_KERNEL);
        if (!kbuf) {
                status = -ENOMEM;
                goto error;
        }

        while (left > 3) {
                /* only write multiples of 4 bytes, so there might */
                /* be as many as 3 bytes left (at the end). */
                len = left;

                if (len > PAGE_SIZE)
                        len = PAGE_SIZE;
                len &= ~3;

                if (drvdata->write_buffer_in_use) {
                        memcpy(kbuf, drvdata->write_buffer,
                                        drvdata->write_buffer_in_use);
                        if (copy_from_user(
                            (((char *)kbuf) + drvdata->write_buffer_in_use),
                            buf + written,
                            len - (drvdata->write_buffer_in_use))) {
                                free_page((unsigned long)kbuf);
                                status = -EFAULT;
                                goto error;
                        }
                } else {
                        if (copy_from_user(kbuf, buf + written, len)) {
                                free_page((unsigned long)kbuf);
                                status = -EFAULT;
                                goto error;
                        }
                }

                status = drvdata->config->set_configuration(drvdata,
                                kbuf, len >> 2);

                if (status) {
                        free_page((unsigned long)kbuf);
                        status = -EFAULT;
                        goto error;
                }
                if (drvdata->write_buffer_in_use) {
                        len -= drvdata->write_buffer_in_use;
                        left -= drvdata->write_buffer_in_use;
                        drvdata->write_buffer_in_use = 0;
                }
                written += len;
                left -= len;
        }
        if ((left > 0) && (left < 4)) {
                if (!copy_from_user(drvdata->write_buffer,
                                                buf + written, left)) {
                        drvdata->write_buffer_in_use = left;
                        written += left;
                        left = 0;
                }
        }

        free_page((unsigned long)kbuf);
        status = written;
 error:
        mutex_unlock(&drvdata->sem);
        return status;
}

static int hwicap_open(struct inode *inode, struct file *file)
{
        struct hwicap_drvdata *drvdata;
        int status;

        mutex_lock(&hwicap_mutex);
        drvdata = container_of(inode->i_cdev, struct hwicap_drvdata, cdev);

        status = mutex_lock_interruptible(&drvdata->sem);
        if (status)
                goto out;

        if (drvdata->is_open) {
                status = -EBUSY;
                goto error;
        }

        status = hwicap_initialize_hwicap(drvdata);
        if (status) {
                dev_err(drvdata->dev, "Failed to open file");
                goto error;
        }

        file->private_data = drvdata;
        drvdata->write_buffer_in_use = 0;
        drvdata->read_buffer_in_use = 0;
        drvdata->is_open = 1;

 error:
        mutex_unlock(&drvdata->sem);
 out:
        mutex_unlock(&hwicap_mutex);
        return status;
}

static int hwicap_release(struct inode *inode, struct file *file)
{
        struct hwicap_drvdata *drvdata = file->private_data;
        int i;
        int status = 0;

        mutex_lock(&drvdata->sem);

        if (drvdata->write_buffer_in_use) {
                /* Flush write buffer. */
                for (i = drvdata->write_buffer_in_use; i < 4; i++)
                        drvdata->write_buffer[i] = 0;

                status = drvdata->config->set_configuration(drvdata,
                                (u32 *) drvdata->write_buffer, 1);
                if (status)
                        goto error;
        }

        status = hwicap_command_desync(drvdata);
        if (status)
                goto error;

 error:
        drvdata->is_open = 0;
        mutex_unlock(&drvdata->sem);
        return status;
}

static const struct file_operations hwicap_fops = {
        .owner = THIS_MODULE,
        .write = hwicap_write,
        .read = hwicap_read,
        .open = hwicap_open,
        .release = hwicap_release,
        .llseek = noop_llseek,
};

static int hwicap_setup(struct platform_device *pdev, int id,
                const struct hwicap_driver_config *config,
                const struct config_registers *config_regs)
{
        dev_t devt;
        struct hwicap_drvdata *drvdata = NULL;
        struct device *dev = &pdev->dev;
        int retval;

        dev_info(dev, "Xilinx icap port driver\n");

        mutex_lock(&icap_sem);

        if (id < 0) {
                for (id = 0; id < HWICAP_DEVICES; id++)
                        if (!probed_devices[id])
                                break;
        }
        if (id < 0 || id >= HWICAP_DEVICES) {
                mutex_unlock(&icap_sem);
                dev_err(dev, "%s%i too large\n", DRIVER_NAME, id);
                return -EINVAL;
        }
        if (probed_devices[id]) {
                mutex_unlock(&icap_sem);
                dev_err(dev, "cannot assign to %s%i; it is already in use\n",
                        DRIVER_NAME, id);
                return -EBUSY;
        }

        probed_devices[id] = 1;
        mutex_unlock(&icap_sem);

        devt = MKDEV(XHWICAP_MAJOR, XHWICAP_MINOR + id);

        drvdata = devm_kzalloc(dev, sizeof(struct hwicap_drvdata), GFP_KERNEL);
        if (!drvdata) {
                retval = -ENOMEM;
                goto failed;
        }
        dev_set_drvdata(dev, drvdata);

        drvdata->base_address = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(drvdata->base_address)) {
                retval = PTR_ERR(drvdata->base_address);
                goto failed;
        }

        drvdata->devt = devt;
        drvdata->dev = dev;
        drvdata->config = config;
        drvdata->config_regs = config_regs;

        mutex_init(&drvdata->sem);
        drvdata->is_open = 0;

        cdev_init(&drvdata->cdev, &hwicap_fops);
        drvdata->cdev.owner = THIS_MODULE;
        retval = cdev_add(&drvdata->cdev, devt, 1);
        if (retval) {
                dev_err(dev, "cdev_add() failed\n");
                goto failed;
        }

        device_create(&icap_class, dev, devt, NULL, "%s%d", DRIVER_NAME, id);
        return 0;               /* success */

 failed:
        mutex_lock(&icap_sem);
        probed_devices[id] = 0;
        mutex_unlock(&icap_sem);

        return retval;
}

static struct hwicap_driver_config buffer_icap_config = {
        .get_configuration = buffer_icap_get_configuration,
        .set_configuration = buffer_icap_set_configuration,
        .get_status = buffer_icap_get_status,
        .reset = buffer_icap_reset,
};

static struct hwicap_driver_config fifo_icap_config = {
        .get_configuration = fifo_icap_get_configuration,
        .set_configuration = fifo_icap_set_configuration,
        .get_status = fifo_icap_get_status,
        .reset = fifo_icap_reset,
};

static int hwicap_drv_probe(struct platform_device *pdev)
{
        const struct config_registers *regs;
        const struct hwicap_driver_config *config;
        const char *family;
        int id = -1;

        config = device_get_match_data(&pdev->dev);

        of_property_read_u32(pdev->dev.of_node, "port-number", &id);

        /* It's most likely that we're using V4, if the family is not
         * specified
         */
        regs = &v4_config_registers;
        if (!of_property_read_string(pdev->dev.of_node, "xlnx,family", &family)) {
                if (!strcmp(family, "virtex2p"))
                        regs = &v2_config_registers;
                else if (!strcmp(family, "virtex4"))
                        regs = &v4_config_registers;
                else if (!strcmp(family, "virtex5"))
                        regs = &v5_config_registers;
                else if (!strcmp(family, "virtex6"))
                        regs = &v6_config_registers;
        }
        return hwicap_setup(pdev, id, config, regs);
}

static void hwicap_drv_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct hwicap_drvdata *drvdata;

        drvdata = dev_get_drvdata(dev);

        device_destroy(&icap_class, drvdata->devt);
        cdev_del(&drvdata->cdev);

        mutex_lock(&icap_sem);
        probed_devices[MINOR(dev->devt)-XHWICAP_MINOR] = 0;
        mutex_unlock(&icap_sem);
}

/* Match table for device tree binding */
static const struct of_device_id hwicap_of_match[] = {
        { .compatible = "xlnx,opb-hwicap-1.00.b", .data = &buffer_icap_config},
        { .compatible = "xlnx,xps-hwicap-1.00.a", .data = &fifo_icap_config},
        {},
};
MODULE_DEVICE_TABLE(of, hwicap_of_match);

static struct platform_driver hwicap_platform_driver = {
        .probe = hwicap_drv_probe,
        .remove = hwicap_drv_remove,
        .driver = {
                .name = DRIVER_NAME,
                .of_match_table = hwicap_of_match,
        },
};

static int __init hwicap_module_init(void)
{
        dev_t devt;
        int retval;

        retval = class_register(&icap_class);
        if (retval)
                return retval;
        mutex_init(&icap_sem);

        devt = MKDEV(XHWICAP_MAJOR, XHWICAP_MINOR);
        retval = register_chrdev_region(devt,
                                        HWICAP_DEVICES,
                                        DRIVER_NAME);
        if (retval < 0)
                return retval;

        retval = platform_driver_register(&hwicap_platform_driver);
        if (retval)
                goto failed;

        return retval;

 failed:
        unregister_chrdev_region(devt, HWICAP_DEVICES);

        return retval;
}

static void __exit hwicap_module_cleanup(void)
{
        dev_t devt = MKDEV(XHWICAP_MAJOR, XHWICAP_MINOR);

        class_unregister(&icap_class);

        platform_driver_unregister(&hwicap_platform_driver);

        unregister_chrdev_region(devt, HWICAP_DEVICES);
}

module_init(hwicap_module_init);
module_exit(hwicap_module_cleanup);

MODULE_AUTHOR("Xilinx, Inc; Xilinx Research Labs Group");
MODULE_DESCRIPTION("Xilinx ICAP Port Driver");
MODULE_LICENSE("GPL");