staging/fwserial: Create loop device the 'tty' way

Register a second tty driver to create loopback devices for
each firewire node. Note that the loopback devices are numbered
from 0; the tty->index is transformed when used to index the
port table.

Remove the hack that previously enabled this.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 93 insertions, 96 deletions

diff --git a/drivers/staging/fwserial/TODO b/drivers/staging/fwserial/TODO
index dc61d9773c6f..382a7959407c 100644
--- a/drivers/staging/fwserial/TODO
+++ b/drivers/staging/fwserial/TODO
@@ -12,16 +12,3 @@ TODOs prior to this driver moving out of staging
 1. This driver uses the same unregistered vendor id that the firewire core does
      (0xd00d1e). Perhaps this could be exposed as a define in
      firewire.h?
-
--- Issues with TTY core --
-  1. Hack for alternate device name scheme
-     - because udev no longer allows device renaming, devices should have
-       their proper names on creation. This is an issue for creating the
-       fwloop<n> device with the fwtty<n> devices because although duplicating
-       roughly the same operations as tty_port_register_device() isn't difficult,
-       access to the tty_class & tty_fops is restricted in scope.
-
-       This is currently being worked around in create_loop_device() by
-       extracting the tty_class ptr and tty_fops ptr from the previously created
-       tty devices. Perhaps an add'l api can be added -- eg.,
-       tty_{port_}register_named_device().
diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index a9e814e5cbdd..3f2d26e7a008 100644
--- a/drivers/staging/fwserial/fwserial.c
+++ b/drivers/staging/fwserial/fwserial.c
@@ -72,6 +72,9 @@ static DEFINE_MUTEX(port_table_lock);
 static bool port_table_corrupt;
 #define FWTTY_INVALID_INDEX  MAX_TOTAL_PORTS
 
+#define loop_idx(port)  (((port)->index) / num_ports)
+#define table_idx(loop) ((loop) * num_ports + num_ttys)
+
 /* total # of tty ports created per fw_card */
 static int num_ports;
 
@@ -79,6 +82,7 @@ static int num_ports;
 static struct kmem_cache *fwtty_txn_cache;
 
 struct tty_driver *fwtty_driver;
+static struct tty_driver *fwloop_driver;
 
 struct fwtty_transaction;
 typedef void (*fwtty_transaction_cb)(struct fw_card *card, int rcode,
@@ -1165,6 +1169,19 @@ static int fwtty_install(struct tty_driver *driver, struct tty_struct *tty)
         return err;
 }
 
+static int fwloop_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+        struct fwtty_port *port = fwtty_port_get(table_idx(tty->index));
+        int err;
+
+        err = tty_standard_install(driver, tty);
+        if (!err)
+                tty->driver_data = port;
+        else
+                fwtty_port_put(port);
+        return err;
+}
+
 static int fwtty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 {
         struct fwtty_port *port = tty->driver_data;
@@ -1601,6 +1618,26 @@ static const struct tty_operations fwtty_ops = {
         .proc_fops =            &fwtty_proc_fops,
 };
 
+static const struct tty_operations fwloop_ops = {
+        .open =                 fwtty_open,
+        .close =                fwtty_close,
+        .hangup =               fwtty_hangup,
+        .cleanup =              fwtty_cleanup,
+        .install =              fwloop_install,
+        .write =                fwtty_write,
+        .write_room =           fwtty_write_room,
+        .chars_in_buffer =      fwtty_chars_in_buffer,
+        .send_xchar =           fwtty_send_xchar,
+        .throttle =             fwtty_throttle,
+        .unthrottle =           fwtty_unthrottle,
+        .ioctl =                fwtty_ioctl,
+        .set_termios =          fwtty_set_termios,
+        .break_ctl =            fwtty_break_ctl,
+        .tiocmget =             fwtty_tiocmget,
+        .tiocmset =             fwtty_tiocmset,
+        .get_icount =           fwtty_get_icount,
+};
+
 static inline int mgmt_pkt_expected_len(__be16 code)
 {
         static const struct fwserial_mgmt_pkt pkt;
@@ -1897,7 +1934,8 @@ free_pkt:
  * The port reference is put by fwtty_cleanup (if a reference was
  * ever taken).
  */
-static void fwserial_close_port(struct fwtty_port *port)
+static void fwserial_close_port(struct tty_driver *driver,
+                                struct fwtty_port *port)
 {
         struct tty_struct *tty;
 
@@ -1909,7 +1947,10 @@ static void fwserial_close_port(struct fwtty_port *port)
         }
         mutex_unlock(&port->port.mutex);
 
-        tty_unregister_device(fwtty_driver, port->index);
+        if (driver == fwloop_driver)
+                tty_unregister_device(driver, loop_idx(port));
+        else
+                tty_unregister_device(driver, port->index);
 }
 
 /**
@@ -2167,78 +2208,6 @@ static void fwserial_remove_peer(struct fwtty_peer *peer)
 }
 
 /**
- * create_loop_device - create a loopback tty device
- * @tty_driver: tty_driver to own loopback device
- * @prototype: ptr to already-assigned 'prototype' tty port
- * @index: index to associate this device with the tty port
- * @parent: device to child to
- *
- * HACK - this is basically tty_port_register_device() with an
- * alternate naming scheme. Suggest tty_port_register_named_device()
- * helper api.
- *
- * Creates a loopback tty device named 'fwloop<n>' which is attached to
- * the local unit in fwserial_add_peer(). Note that <n> in the device
- * name advances in increments of port allocation blocks, ie., for port
- * indices 0..3, the device name will be 'fwloop0'; for 4..7, 'fwloop1',
- * and so on.
- *
- * Only one loopback device should be created per fw_card.
- */
-static void release_loop_device(struct device *dev)
-{
-        kfree(dev);
-}
-
-static struct device *create_loop_device(struct tty_driver *driver,
-                                         struct fwtty_port *prototype,
-                                         struct fwtty_port *port,
-                                         struct device *parent)
-{
-        char name[64];
-        int index = port->index;
-        dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
-        struct device *dev = NULL;
-        int err;
-
-        if (index >= fwtty_driver->num)
-                return ERR_PTR(-EINVAL);
-
-        snprintf(name, 64, "%s%d", loop_dev_name, index / num_ports);
-
-        tty_port_link_device(&port->port, driver, index);
-
-        cdev_init(&driver->cdevs[index], driver->cdevs[prototype->index].ops);
-        driver->cdevs[index].owner = driver->owner;
-        err = cdev_add(&driver->cdevs[index], devt, 1);
-        if (err)
-                return ERR_PTR(err);
-
-        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-        if (!dev) {
-                cdev_del(&driver->cdevs[index]);
-                return ERR_PTR(-ENOMEM);
-        }
-
-        dev->devt = devt;
-        dev->class = prototype->device->class;
-        dev->parent = parent;
-        dev->release = release_loop_device;
-        dev_set_name(dev, "%s", name);
-        dev->groups = NULL;
-        dev_set_drvdata(dev, NULL);
-
-        err = device_register(dev);
-        if (err) {
-                put_device(dev);
-                cdev_del(&driver->cdevs[index]);
-                return ERR_PTR(err);
-        }
-
-        return dev;
-}
-
-/**
  * fwserial_create - init everything to create TTYs for a specific fw_card
  * @unit: fw_unit for first 'serial' unit device probed for this fw_card
  *
@@ -2336,17 +2305,17 @@ static int fwserial_create(struct fw_unit *unit)
         if (create_loop_dev) {
                 struct device *loop_dev;
 
-                loop_dev = create_loop_device(fwtty_driver,
-                                              serial->ports[0],
-                                              serial->ports[num_ttys],
-                                              card->device);
+                loop_dev = tty_port_register_device(&serial->ports[j]->port,
+                                                    fwloop_driver,
+                                                    loop_idx(serial->ports[j]),
+                                                    card->device);
                 if (IS_ERR(loop_dev)) {
                         err = PTR_ERR(loop_dev);
                         fwtty_err(&unit, "create loop device failed (%d)", err);
                         goto unregister_ttys;
                 }
-                serial->ports[num_ttys]->device = loop_dev;
-                serial->ports[num_ttys]->loopback = true;
+                serial->ports[j]->device = loop_dev;
+                serial->ports[j]->loopback = true;
         }
 
         list_add_rcu(&serial->list, &fwserial_list);
@@ -2362,6 +2331,8 @@ static int fwserial_create(struct fw_unit *unit)
 
         /* fall-through to error processing */
         list_del_rcu(&serial->list);
+        if (create_loop_dev)
+                tty_unregister_device(fwloop_driver, loop_idx(serial->ports[j]));
 unregister_ttys:
         for (--j; j >= 0; --j)
                 tty_unregister_device(fwtty_driver, serial->ports[j]->index);
@@ -2450,8 +2421,10 @@ static int fwserial_remove(struct device *dev)
                 /* unlink from the fwserial_list here */
                 list_del_rcu(&serial->list);
 
-                for (i = 0; i < num_ports; ++i)
-                        fwserial_close_port(serial->ports[i]);
+                for (i = 0; i < num_ttys; ++i)
+                        fwserial_close_port(fwtty_driver, serial->ports[i]);
+                if (create_loop_dev)
+                        fwserial_close_port(fwloop_driver, serial->ports[i]);
                 kref_put(&serial->kref, fwserial_destroy);
         }
         mutex_unlock(&fwserial_list_mutex);
@@ -2872,12 +2845,39 @@ static int __init fwserial_init(void)
                 goto put_tty;
         }
 
+        if (create_loop_dev) {
+                fwloop_driver = alloc_tty_driver(MAX_TOTAL_PORTS / num_ports);
+                if (!fwloop_driver) {
+                        err = -ENOMEM;
+                        goto unregister_driver;
+                }
+
+                fwloop_driver->driver_name      = KBUILD_MODNAME "_loop";
+                fwloop_driver->name             = loop_dev_name;
+                fwloop_driver->major            = 0;
+                fwloop_driver->minor_start      = 0;
+                fwloop_driver->type             = TTY_DRIVER_TYPE_SERIAL;
+                fwloop_driver->subtype          = SERIAL_TYPE_NORMAL;
+                fwloop_driver->flags            = TTY_DRIVER_REAL_RAW |
+                                                        TTY_DRIVER_DYNAMIC_DEV;
+
+                fwloop_driver->init_termios         = tty_std_termios;
+                fwloop_driver->init_termios.c_cflag  |= CLOCAL;
+                tty_set_operations(fwloop_driver, &fwloop_ops);
+
+                err = tty_register_driver(fwloop_driver);
+                if (err) {
+                        driver_err("register loop driver failed (%d)", err);
+                        goto put_loop;
+                }
+        }
+
         fwtty_txn_cache = kmem_cache_create("fwtty_txn_cache",
                                             sizeof(struct fwtty_transaction),
                                             0, 0, fwtty_txn_constructor);
         if (!fwtty_txn_cache) {
                 err = -ENOMEM;
-                goto unregister_driver;
+                goto unregister_loop;
         }
 
         /*
@@ -2919,6 +2919,12 @@ remove_handler:
         fw_core_remove_address_handler(&fwserial_mgmt_addr_handler);
 destroy_cache:
         kmem_cache_destroy(fwtty_txn_cache);
+unregister_loop:
+        if (create_loop_dev)
+                tty_unregister_driver(fwloop_driver);
+put_loop:
+        if (create_loop_dev)
+                put_tty_driver(fwloop_driver);
 unregister_driver:
         tty_unregister_driver(fwtty_driver);
 put_tty:
@@ -2932,6 +2938,10 @@ static void __exit fwserial_exit(void)
         fw_core_remove_descriptor(&fwserial_unit_directory);
         fw_core_remove_address_handler(&fwserial_mgmt_addr_handler);
         kmem_cache_destroy(fwtty_txn_cache);
+        if (create_loop_dev) {
+                tty_unregister_driver(fwloop_driver);
+                put_tty_driver(fwloop_driver);
+        }
         tty_unregister_driver(fwtty_driver);
         put_tty_driver(fwtty_driver);
 }