// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Silicon Labs C2 port core Linux support
 *
 *  Copyright (c) 2007 Rodolfo Giometti <giometti@linux.it>
 *  Copyright (c) 2007 Eurotech S.p.A. <info@eurotech.it>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <linux/c2port.h>

#define DRIVER_NAME             "c2port"
#define DRIVER_VERSION          "0.51.0"

static DEFINE_SPINLOCK(c2port_idr_lock);
static DEFINE_IDR(c2port_idr);

/*
 * Local variables
 */

static struct class *c2port_class;

/*
 * C2 registers & commands defines
 */

/* C2 registers */
#define C2PORT_DEVICEID         0x00
#define C2PORT_REVID            0x01
#define C2PORT_FPCTL            0x02
#define C2PORT_FPDAT            0xB4

/* C2 interface commands */
#define C2PORT_GET_VERSION      0x01
#define C2PORT_DEVICE_ERASE     0x03
#define C2PORT_BLOCK_READ       0x06
#define C2PORT_BLOCK_WRITE      0x07
#define C2PORT_PAGE_ERASE       0x08

/* C2 status return codes */
#define C2PORT_INVALID_COMMAND  0x00
#define C2PORT_COMMAND_FAILED   0x02
#define C2PORT_COMMAND_OK       0x0d

/*
 * C2 port low level signal managements
 */

static void c2port_reset(struct c2port_device *dev)
{
        struct c2port_ops *ops = dev->ops;

        /* To reset the device we have to keep clock line low for at least
         * 20us.
         */
        local_irq_disable();
        ops->c2ck_set(dev, 0);
        udelay(25);
        ops->c2ck_set(dev, 1);
        local_irq_enable();

        udelay(1);
}

static void c2port_strobe_ck(struct c2port_device *dev)
{
        struct c2port_ops *ops = dev->ops;

        /* During hi-low-hi transition we disable local IRQs to avoid
         * interructions since C2 port specification says that it must be
         * shorter than 5us, otherwise the microcontroller may consider
         * it as a reset signal!
         */
        local_irq_disable();
        ops->c2ck_set(dev, 0);
        udelay(1);
        ops->c2ck_set(dev, 1);
        local_irq_enable();

        udelay(1);
}

/*
 * C2 port basic functions
 */

static void c2port_write_ar(struct c2port_device *dev, u8 addr)
{
        struct c2port_ops *ops = dev->ops;
        int i;

        /* START field */
        c2port_strobe_ck(dev);

        /* INS field (11b, LSB first) */
        ops->c2d_dir(dev, 0);
        ops->c2d_set(dev, 1);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 1);
        c2port_strobe_ck(dev);

        /* ADDRESS field */
        for (i = 0; i < 8; i++) {
                ops->c2d_set(dev, addr & 0x01);
                c2port_strobe_ck(dev);

                addr >>= 1;
        }

        /* STOP field */
        ops->c2d_dir(dev, 1);
        c2port_strobe_ck(dev);
}

static int c2port_read_ar(struct c2port_device *dev, u8 *addr)
{
        struct c2port_ops *ops = dev->ops;
        int i;

        /* START field */
        c2port_strobe_ck(dev);

        /* INS field (10b, LSB first) */
        ops->c2d_dir(dev, 0);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 1);
        c2port_strobe_ck(dev);

        /* ADDRESS field */
        ops->c2d_dir(dev, 1);
        *addr = 0;
        for (i = 0; i < 8; i++) {
                *addr >>= 1;    /* shift in 8-bit ADDRESS field LSB first */

                c2port_strobe_ck(dev);
                if (ops->c2d_get(dev))
                        *addr |= 0x80;
        }

        /* STOP field */
        c2port_strobe_ck(dev);

        return 0;
}

static int c2port_write_dr(struct c2port_device *dev, u8 data)
{
        struct c2port_ops *ops = dev->ops;
        int timeout, i;

        /* START field */
        c2port_strobe_ck(dev);

        /* INS field (01b, LSB first) */
        ops->c2d_dir(dev, 0);
        ops->c2d_set(dev, 1);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);

        /* LENGTH field (00b, LSB first -> 1 byte) */
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);

        /* DATA field */
        for (i = 0; i < 8; i++) {
                ops->c2d_set(dev, data & 0x01);
                c2port_strobe_ck(dev);

                data >>= 1;
        }

        /* WAIT field */
        ops->c2d_dir(dev, 1);
        timeout = 20;
        do {
                c2port_strobe_ck(dev);
                if (ops->c2d_get(dev))
                        break;

                udelay(1);
        } while (--timeout > 0);
        if (timeout == 0)
                return -EIO;

        /* STOP field */
        c2port_strobe_ck(dev);

        return 0;
}

static int c2port_read_dr(struct c2port_device *dev, u8 *data)
{
        struct c2port_ops *ops = dev->ops;
        int timeout, i;

        /* START field */
        c2port_strobe_ck(dev);

        /* INS field (00b, LSB first) */
        ops->c2d_dir(dev, 0);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);

        /* LENGTH field (00b, LSB first -> 1 byte) */
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);
        ops->c2d_set(dev, 0);
        c2port_strobe_ck(dev);

        /* WAIT field */
        ops->c2d_dir(dev, 1);
        timeout = 20;
        do {
                c2port_strobe_ck(dev);
                if (ops->c2d_get(dev))
                        break;

                udelay(1);
        } while (--timeout > 0);
        if (timeout == 0)
                return -EIO;

        /* DATA field */
        *data = 0;
        for (i = 0; i < 8; i++) {
                *data >>= 1;    /* shift in 8-bit DATA field LSB first */

                c2port_strobe_ck(dev);
                if (ops->c2d_get(dev))
                        *data |= 0x80;
        }

        /* STOP field */
        c2port_strobe_ck(dev);

        return 0;
}

static int c2port_poll_in_busy(struct c2port_device *dev)
{
        u8 addr;
        int ret, timeout = 20;

        do {
                ret = (c2port_read_ar(dev, &addr));
                if (ret < 0)
                        return -EIO;

                if (!(addr & 0x02))
                        break;

                udelay(1);
        } while (--timeout > 0);
        if (timeout == 0)
                return -EIO;

        return 0;
}

static int c2port_poll_out_ready(struct c2port_device *dev)
{
        u8 addr;
        int ret, timeout = 10000; /* erase flash needs long time... */

        do {
                ret = (c2port_read_ar(dev, &addr));
                if (ret < 0)
                        return -EIO;

                if (addr & 0x01)
                        break;

                udelay(1);
        } while (--timeout > 0);
        if (timeout == 0)
                return -EIO;

        return 0;
}

/*
 * sysfs methods
 */

static ssize_t c2port_show_name(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);

        return sprintf(buf, "%s\n", c2dev->name);
}
static DEVICE_ATTR(name, 0444, c2port_show_name, NULL);

static ssize_t c2port_show_flash_blocks_num(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        struct c2port_ops *ops = c2dev->ops;

        return sprintf(buf, "%d\n", ops->blocks_num);
}
static DEVICE_ATTR(flash_blocks_num, 0444, c2port_show_flash_blocks_num, NULL);

static ssize_t c2port_show_flash_block_size(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        struct c2port_ops *ops = c2dev->ops;

        return sprintf(buf, "%d\n", ops->block_size);
}
static DEVICE_ATTR(flash_block_size, 0444, c2port_show_flash_block_size, NULL);

static ssize_t c2port_show_flash_size(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        struct c2port_ops *ops = c2dev->ops;

        return sprintf(buf, "%d\n", ops->blocks_num * ops->block_size);
}
static DEVICE_ATTR(flash_size, 0444, c2port_show_flash_size, NULL);

static ssize_t access_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n", c2dev->access);
}

static ssize_t access_store(struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        struct c2port_ops *ops = c2dev->ops;
        int status, ret;

        ret = sscanf(buf, "%d", &status);
        if (ret != 1)
                return -EINVAL;

        mutex_lock(&c2dev->mutex);

        c2dev->access = !!status;

        /* If access is "on" clock should be HIGH _before_ setting the line
         * as output and data line should be set as INPUT anyway */
        if (c2dev->access)
                ops->c2ck_set(c2dev, 1);
        ops->access(c2dev, c2dev->access);
        if (c2dev->access)
                ops->c2d_dir(c2dev, 1);

        mutex_unlock(&c2dev->mutex);

        return count;
}
static DEVICE_ATTR_RW(access);

static ssize_t c2port_store_reset(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);

        /* Check the device access status */
        if (!c2dev->access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);

        c2port_reset(c2dev);
        c2dev->flash_access = 0;

        mutex_unlock(&c2dev->mutex);

        return count;
}
static DEVICE_ATTR(reset, 0200, NULL, c2port_store_reset);

static ssize_t __c2port_show_dev_id(struct c2port_device *dev, char *buf)
{
        u8 data;
        int ret;

        /* Select DEVICEID register for C2 data register accesses */
        c2port_write_ar(dev, C2PORT_DEVICEID);

        /* Read and return the device ID register */
        ret = c2port_read_dr(dev, &data);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%d\n", data);
}

static ssize_t c2port_show_dev_id(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        ssize_t ret;

        /* Check the device access status */
        if (!c2dev->access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_show_dev_id(c2dev, buf);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0)
                dev_err(dev, "cannot read from %s\n", c2dev->name);

        return ret;
}
static DEVICE_ATTR(dev_id, 0444, c2port_show_dev_id, NULL);

static ssize_t __c2port_show_rev_id(struct c2port_device *dev, char *buf)
{
        u8 data;
        int ret;

        /* Select REVID register for C2 data register accesses */
        c2port_write_ar(dev, C2PORT_REVID);

        /* Read and return the revision ID register */
        ret = c2port_read_dr(dev, &data);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%d\n", data);
}

static ssize_t c2port_show_rev_id(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        ssize_t ret;

        /* Check the device access status */
        if (!c2dev->access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_show_rev_id(c2dev, buf);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0)
                dev_err(c2dev->dev, "cannot read from %s\n", c2dev->name);

        return ret;
}
static DEVICE_ATTR(rev_id, 0444, c2port_show_rev_id, NULL);

static ssize_t c2port_show_flash_access(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n", c2dev->flash_access);
}

static ssize_t __c2port_store_flash_access(struct c2port_device *dev,
                                                int status)
{
        int ret;

        /* Check the device access status */
        if (!dev->access)
                return -EBUSY;

        dev->flash_access = !!status;

        /* If flash_access is off we have nothing to do... */
        if (dev->flash_access == 0)
                return 0;

        /* Target the C2 flash programming control register for C2 data
         * register access */
        c2port_write_ar(dev, C2PORT_FPCTL);

        /* Write the first keycode to enable C2 Flash programming */
        ret = c2port_write_dr(dev, 0x02);
        if (ret < 0)
                return ret;

        /* Write the second keycode to enable C2 Flash programming */
        ret = c2port_write_dr(dev, 0x01);
        if (ret < 0)
                return ret;

        /* Delay for at least 20ms to ensure the target is ready for
         * C2 flash programming */
        mdelay(25);

        return 0;
}

static ssize_t c2port_store_flash_access(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        int status;
        ssize_t ret;

        ret = sscanf(buf, "%d", &status);
        if (ret != 1)
                return -EINVAL;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_store_flash_access(c2dev, status);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0) {
                dev_err(c2dev->dev, "cannot enable %s flash programming\n",
                        c2dev->name);
                return ret;
        }

        return count;
}
static DEVICE_ATTR(flash_access, 0644, c2port_show_flash_access,
                   c2port_store_flash_access);

static ssize_t __c2port_write_flash_erase(struct c2port_device *dev)
{
        u8 status;
        int ret;

        /* Target the C2 flash programming data register for C2 data register
         * access.
         */
        c2port_write_ar(dev, C2PORT_FPDAT);

        /* Send device erase command */
        c2port_write_dr(dev, C2PORT_DEVICE_ERASE);

        /* Wait for input acknowledge */
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Should check status before starting FLASH access sequence */

        /* Wait for status information */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        /* Read flash programming interface status */
        ret = c2port_read_dr(dev, &status);
        if (ret < 0)
                return ret;
        if (status != C2PORT_COMMAND_OK)
                return -EBUSY;

        /* Send a three-byte arming sequence to enable the device erase.
         * If the sequence is not received correctly, the command will be
         * ignored.
         * Sequence is: 0xde, 0xad, 0xa5.
         */
        c2port_write_dr(dev, 0xde);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;
        c2port_write_dr(dev, 0xad);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;
        c2port_write_dr(dev, 0xa5);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        return 0;
}

static ssize_t c2port_store_flash_erase(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(dev);
        int ret;

        /* Check the device and flash access status */
        if (!c2dev->access || !c2dev->flash_access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_write_flash_erase(c2dev);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0) {
                dev_err(c2dev->dev, "cannot erase %s flash\n", c2dev->name);
                return ret;
        }

        return count;
}
static DEVICE_ATTR(flash_erase, 0200, NULL, c2port_store_flash_erase);

static ssize_t __c2port_read_flash_data(struct c2port_device *dev,
                                char *buffer, loff_t offset, size_t count)
{
        struct c2port_ops *ops = dev->ops;
        u8 status, nread = 128;
        int i, ret;

        /* Check for flash end */
        if (offset >= ops->block_size * ops->blocks_num)
                return 0;

        if (ops->block_size * ops->blocks_num - offset < nread)
                nread = ops->block_size * ops->blocks_num - offset;
        if (count < nread)
                nread = count;
        if (nread == 0)
                return nread;

        /* Target the C2 flash programming data register for C2 data register
         * access */
        c2port_write_ar(dev, C2PORT_FPDAT);

        /* Send flash block read command */
        c2port_write_dr(dev, C2PORT_BLOCK_READ);

        /* Wait for input acknowledge */
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Should check status before starting FLASH access sequence */

        /* Wait for status information */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        /* Read flash programming interface status */
        ret = c2port_read_dr(dev, &status);
        if (ret < 0)
                return ret;
        if (status != C2PORT_COMMAND_OK)
                return -EBUSY;

        /* Send address high byte */
        c2port_write_dr(dev, offset >> 8);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Send address low byte */
        c2port_write_dr(dev, offset & 0x00ff);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Send address block size */
        c2port_write_dr(dev, nread);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Should check status before reading FLASH block */

        /* Wait for status information */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        /* Read flash programming interface status */
        ret = c2port_read_dr(dev, &status);
        if (ret < 0)
                return ret;
        if (status != C2PORT_COMMAND_OK)
                return -EBUSY;

        /* Read flash block */
        for (i = 0; i < nread; i++) {
                ret = c2port_poll_out_ready(dev);
                if (ret < 0)
                        return ret;

                ret = c2port_read_dr(dev, buffer+i);
                if (ret < 0)
                        return ret;
        }

        return nread;
}

static ssize_t c2port_read_flash_data(struct file *filp, struct kobject *kobj,
                                struct bin_attribute *attr,
                                char *buffer, loff_t offset, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(kobj_to_dev(kobj));
        ssize_t ret;

        /* Check the device and flash access status */
        if (!c2dev->access || !c2dev->flash_access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_read_flash_data(c2dev, buffer, offset, count);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0)
                dev_err(c2dev->dev, "cannot read %s flash\n", c2dev->name);

        return ret;
}

static ssize_t __c2port_write_flash_data(struct c2port_device *dev,
                                char *buffer, loff_t offset, size_t count)
{
        struct c2port_ops *ops = dev->ops;
        u8 status, nwrite = 128;
        int i, ret;

        if (nwrite > count)
                nwrite = count;
        if (ops->block_size * ops->blocks_num - offset < nwrite)
                nwrite = ops->block_size * ops->blocks_num - offset;

        /* Check for flash end */
        if (offset >= ops->block_size * ops->blocks_num)
                return -EINVAL;

        /* Target the C2 flash programming data register for C2 data register
         * access */
        c2port_write_ar(dev, C2PORT_FPDAT);

        /* Send flash block write command */
        c2port_write_dr(dev, C2PORT_BLOCK_WRITE);

        /* Wait for input acknowledge */
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Should check status before starting FLASH access sequence */

        /* Wait for status information */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        /* Read flash programming interface status */
        ret = c2port_read_dr(dev, &status);
        if (ret < 0)
                return ret;
        if (status != C2PORT_COMMAND_OK)
                return -EBUSY;

        /* Send address high byte */
        c2port_write_dr(dev, offset >> 8);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Send address low byte */
        c2port_write_dr(dev, offset & 0x00ff);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Send address block size */
        c2port_write_dr(dev, nwrite);
        ret = c2port_poll_in_busy(dev);
        if (ret < 0)
                return ret;

        /* Should check status before writing FLASH block */

        /* Wait for status information */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        /* Read flash programming interface status */
        ret = c2port_read_dr(dev, &status);
        if (ret < 0)
                return ret;
        if (status != C2PORT_COMMAND_OK)
                return -EBUSY;

        /* Write flash block */
        for (i = 0; i < nwrite; i++) {
                ret = c2port_write_dr(dev, *(buffer+i));
                if (ret < 0)
                        return ret;

                ret = c2port_poll_in_busy(dev);
                if (ret < 0)
                        return ret;

        }

        /* Wait for last flash write to complete */
        ret = c2port_poll_out_ready(dev);
        if (ret < 0)
                return ret;

        return nwrite;
}

static ssize_t c2port_write_flash_data(struct file *filp, struct kobject *kobj,
                                struct bin_attribute *attr,
                                char *buffer, loff_t offset, size_t count)
{
        struct c2port_device *c2dev = dev_get_drvdata(kobj_to_dev(kobj));
        int ret;

        /* Check the device access status */
        if (!c2dev->access || !c2dev->flash_access)
                return -EBUSY;

        mutex_lock(&c2dev->mutex);
        ret = __c2port_write_flash_data(c2dev, buffer, offset, count);
        mutex_unlock(&c2dev->mutex);

        if (ret < 0)
                dev_err(c2dev->dev, "cannot write %s flash\n", c2dev->name);

        return ret;
}
/* size is computed at run-time */
static BIN_ATTR(flash_data, 0644, c2port_read_flash_data,
                c2port_write_flash_data, 0);

/*
 * Class attributes
 */
static struct attribute *c2port_attrs[] = {
        &dev_attr_name.attr,
        &dev_attr_flash_blocks_num.attr,
        &dev_attr_flash_block_size.attr,
        &dev_attr_flash_size.attr,
        &dev_attr_access.attr,
        &dev_attr_reset.attr,
        &dev_attr_dev_id.attr,
        &dev_attr_rev_id.attr,
        &dev_attr_flash_access.attr,
        &dev_attr_flash_erase.attr,
        NULL,
};

static struct bin_attribute *c2port_bin_attrs[] = {
        &bin_attr_flash_data,
        NULL,
};

static const struct attribute_group c2port_group = {
        .attrs = c2port_attrs,
        .bin_attrs = c2port_bin_attrs,
};

static const struct attribute_group *c2port_groups[] = {
        &c2port_group,
        NULL,
};

/*
 * Exported functions
 */

struct c2port_device *c2port_device_register(char *name,
                                        struct c2port_ops *ops, void *devdata)
{
        struct c2port_device *c2dev;
        int ret;

        if (unlikely(!ops) || unlikely(!ops->access) || \
                unlikely(!ops->c2d_dir) || unlikely(!ops->c2ck_set) || \
                unlikely(!ops->c2d_get) || unlikely(!ops->c2d_set))
                return ERR_PTR(-EINVAL);

        c2dev = kzalloc(sizeof(struct c2port_device), GFP_KERNEL);
        if (unlikely(!c2dev))
                return ERR_PTR(-ENOMEM);

        idr_preload(GFP_KERNEL);
        spin_lock_irq(&c2port_idr_lock);
        ret = idr_alloc(&c2port_idr, c2dev, 0, 0, GFP_NOWAIT);
        spin_unlock_irq(&c2port_idr_lock);
        idr_preload_end();

        if (ret < 0)
                goto error_idr_alloc;
        c2dev->id = ret;

        bin_attr_flash_data.size = ops->blocks_num * ops->block_size;

        c2dev->dev = device_create(c2port_class, NULL, 0, c2dev,
                                   "c2port%d", c2dev->id);
        if (IS_ERR(c2dev->dev)) {
                ret = PTR_ERR(c2dev->dev);
                goto error_device_create;
        }
        dev_set_drvdata(c2dev->dev, c2dev);

        strncpy(c2dev->name, name, C2PORT_NAME_LEN - 1);
        c2dev->ops = ops;
        mutex_init(&c2dev->mutex);

        /* By default C2 port access is off */
        c2dev->access = c2dev->flash_access = 0;
        ops->access(c2dev, 0);

        dev_info(c2dev->dev, "C2 port %s added\n", name);
        dev_info(c2dev->dev, "%s flash has %d blocks x %d bytes "
                                "(%d bytes total)\n",
                                name, ops->blocks_num, ops->block_size,
                                ops->blocks_num * ops->block_size);

        return c2dev;

error_device_create:
        spin_lock_irq(&c2port_idr_lock);
        idr_remove(&c2port_idr, c2dev->id);
        spin_unlock_irq(&c2port_idr_lock);

error_idr_alloc:
        kfree(c2dev);

        return ERR_PTR(ret);
}
EXPORT_SYMBOL(c2port_device_register);

void c2port_device_unregister(struct c2port_device *c2dev)
{
        if (!c2dev)
                return;

        dev_info(c2dev->dev, "C2 port %s removed\n", c2dev->name);

        spin_lock_irq(&c2port_idr_lock);
        idr_remove(&c2port_idr, c2dev->id);
        spin_unlock_irq(&c2port_idr_lock);

        device_destroy(c2port_class, c2dev->id);

        kfree(c2dev);
}
EXPORT_SYMBOL(c2port_device_unregister);

/*
 * Module stuff
 */

static int __init c2port_init(void)
{
        printk(KERN_INFO "Silicon Labs C2 port support v. " DRIVER_VERSION
                " - (C) 2007 Rodolfo Giometti\n");

        c2port_class = class_create(THIS_MODULE, "c2port");
        if (IS_ERR(c2port_class)) {
                printk(KERN_ERR "c2port: failed to allocate class\n");
                return PTR_ERR(c2port_class);
        }
        c2port_class->dev_groups = c2port_groups;

        return 0;
}

static void __exit c2port_exit(void)
{
        class_destroy(c2port_class);
}

module_init(c2port_init);
module_exit(c2port_exit);

MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("Silicon Labs C2 port support v. " DRIVER_VERSION);
MODULE_LICENSE("GPL");