#include <linux/module.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/cdev.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <linux/slab.h>
#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/sg.h>
#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
#define BSG_VERSION "0.4"
struct bsg_device {
struct request_queue *queue;
struct device device;
struct cdev cdev;
int max_queue;
unsigned int timeout;
unsigned int reserved_size;
bsg_sg_io_fn *sg_io_fn;
};
static inline struct bsg_device *to_bsg_device(struct inode *inode)
{
return container_of(inode->i_cdev, struct bsg_device, cdev);
}
#define BSG_DEFAULT_CMDS 64
#define BSG_MAX_DEVS (1 << MINORBITS)
static DEFINE_IDA(bsg_minor_ida);
static const struct class bsg_class;
static int bsg_major;
static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)
{
unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;
if (hdr->timeout)
timeout = msecs_to_jiffies(hdr->timeout);
else if (bd->timeout)
timeout = bd->timeout;
return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);
}
static int bsg_sg_io(struct bsg_device *bd, bool open_for_write,
void __user *uarg)
{
struct sg_io_v4 hdr;
int ret;
if (copy_from_user(&hdr, uarg, sizeof(hdr)))
return -EFAULT;
if (hdr.guard != 'Q')
return -EINVAL;
ret = bd->sg_io_fn(bd->queue, &hdr, open_for_write,
bsg_timeout(bd, &hdr));
if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
return -EFAULT;
return ret;
}
static int bsg_open(struct inode *inode, struct file *file)
{
if (!blk_get_queue(to_bsg_device(inode)->queue))
return -ENXIO;
return 0;
}
static int bsg_release(struct inode *inode, struct file *file)
{
blk_put_queue(to_bsg_device(inode)->queue);
return 0;
}
static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
{
return put_user(READ_ONCE(bd->max_queue), uarg);
}
static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
{
int max_queue;
if (get_user(max_queue, uarg))
return -EFAULT;
if (max_queue < 1)
return -EINVAL;
WRITE_ONCE(bd->max_queue, max_queue);
return 0;
}
static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct bsg_device *bd = to_bsg_device(file_inode(file));
struct request_queue *q = bd->queue;
void __user *uarg = (void __user *) arg;
int __user *intp = uarg;
int val;
switch (cmd) {
case SG_GET_COMMAND_Q:
return bsg_get_command_q(bd, uarg);
case SG_SET_COMMAND_Q:
return bsg_set_command_q(bd, uarg);
case SG_GET_VERSION_NUM:
return put_user(30527, intp);
case SCSI_IOCTL_GET_IDLUN:
return put_user(0, intp);
case SCSI_IOCTL_GET_BUS_NUMBER:
return put_user(0, intp);
case SG_SET_TIMEOUT:
if (get_user(val, intp))
return -EFAULT;
bd->timeout = clock_t_to_jiffies(val);
return 0;
case SG_GET_TIMEOUT:
return jiffies_to_clock_t(bd->timeout);
case SG_GET_RESERVED_SIZE:
return put_user(min(bd->reserved_size, queue_max_bytes(q)),
intp);
case SG_SET_RESERVED_SIZE:
if (get_user(val, intp))
return -EFAULT;
if (val < 0)
return -EINVAL;
bd->reserved_size =
min_t(unsigned int, val, queue_max_bytes(q));
return 0;
case SG_EMULATED_HOST:
return put_user(1, intp);
case SG_IO:
return bsg_sg_io(bd, file->f_mode & FMODE_WRITE, uarg);
case SCSI_IOCTL_SEND_COMMAND:
pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
current->comm);
return -EINVAL;
default:
return -ENOTTY;
}
}
static const struct file_operations bsg_fops = {
.open = bsg_open,
.release = bsg_release,
.unlocked_ioctl = bsg_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.owner = THIS_MODULE,
.llseek = default_llseek,
};
static void bsg_device_release(struct device *dev)
{
struct bsg_device *bd = container_of(dev, struct bsg_device, device);
ida_free(&bsg_minor_ida, MINOR(bd->device.devt));
kfree(bd);
}
void bsg_unregister_queue(struct bsg_device *bd)
{
struct gendisk *disk = bd->queue->disk;
if (disk && disk->queue_kobj.sd)
sysfs_remove_link(&disk->queue_kobj, "bsg");
cdev_device_del(&bd->cdev, &bd->device);
put_device(&bd->device);
}
EXPORT_SYMBOL_GPL(bsg_unregister_queue);
struct bsg_device *bsg_register_queue(struct request_queue *q,
struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)
{
struct bsg_device *bd;
int ret;
bd = kzalloc_obj(*bd);
if (!bd)
return ERR_PTR(-ENOMEM);
bd->max_queue = BSG_DEFAULT_CMDS;
bd->reserved_size = INT_MAX;
bd->queue = q;
bd->sg_io_fn = sg_io_fn;
ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
if (ret < 0) {
if (ret == -ENOSPC)
dev_err(parent, "bsg: too many bsg devices\n");
kfree(bd);
return ERR_PTR(ret);
}
bd->device.devt = MKDEV(bsg_major, ret);
bd->device.class = &bsg_class;
bd->device.parent = parent;
bd->device.release = bsg_device_release;
dev_set_name(&bd->device, "%s", name);
device_initialize(&bd->device);
cdev_init(&bd->cdev, &bsg_fops);
bd->cdev.owner = THIS_MODULE;
ret = cdev_device_add(&bd->cdev, &bd->device);
if (ret)
goto out_put_device;
if (q->disk && q->disk->queue_kobj.sd) {
ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj,
"bsg");
if (ret)
goto out_device_del;
}
return bd;
out_device_del:
cdev_device_del(&bd->cdev, &bd->device);
out_put_device:
put_device(&bd->device);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(bsg_register_queue);
static char *bsg_devnode(const struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
}
static const struct class bsg_class = {
.name = "bsg",
.devnode = bsg_devnode,
};
static int __init bsg_init(void)
{
dev_t devid;
int ret;
ret = class_register(&bsg_class);
if (ret)
return ret;
ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
if (ret)
goto destroy_bsg_class;
bsg_major = MAJOR(devid);
printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
" loaded (major %d)\n", bsg_major);
return 0;
destroy_bsg_class:
class_unregister(&bsg_class);
return ret;
}
MODULE_AUTHOR("Jens Axboe");
MODULE_DESCRIPTION(BSG_DESCRIPTION);
MODULE_LICENSE("GPL");
device_initcall(bsg_init);
