ide: add warm-plug support for IDE devices (take 2)

* Add 'struct class ide_port_class' ('ide_port' class) and a 'struct
  device *portdev' ('ide_port' class device) in ide_hwif_t.

* Register 'ide_port' class in ide_init() and unregister it in
  cleanup_module().

* Create ->portdev in ide_register_port () and unregister it in
  ide_unregister().

* Add "delete_devices" class device attribute for unregistering IDE devices
  on a port and "scan" one for probing+registering IDE devices on a port.

* Add ide_sysfs_register_port() helper for registering "delete_devices"
  and "scan" attributes with ->portdev.  Call it in ide_device_add_all().

* Document IDE warm-plug support in Documentation/ide/warm-plug-howto.txt.

v2:
* Convert patch from using 'struct class_device' to use 'struct device'.
  (thanks to Kay Sievers for doing it)

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

4 files changed, 110 insertions, 3 deletions

diff --git a/Documentation/ide/warm-plug-howto.txt b/Documentation/ide/warm-plug-howto.txt
new file mode 100644
index 000000000000..d5885468b072
--- /dev/null
+++ b/Documentation/ide/warm-plug-howto.txt
@@ -0,0 +1,13 @@
+
+IDE warm-plug HOWTO
+===================
+
+To warm-plug devices on a port 'idex':
+
+# echo -n "1" > /sys/class/ide_port/idex/delete_devices
+
+unplug old device(s) and plug new device(s)
+
+# echo -n "1" > /sys/class/ide_port/idex/scan
+
+done
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 468c4ac4181d..510254ab3c9b 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -623,7 +623,7 @@ static void hwif_release_dev (struct device *dev)
         complete(&hwif->gendev_rel_comp);
 }
 
-static void ide_register_port(ide_hwif_t *hwif)
+static int ide_register_port(ide_hwif_t *hwif)
 {
         int ret;
 
@@ -639,9 +639,23 @@ static void ide_register_port(ide_hwif_t *hwif)
         }
         hwif->gendev.release = hwif_release_dev;
         ret = device_register(&hwif->gendev);
-        if (ret < 0)
+        if (ret < 0) {
                 printk(KERN_WARNING "IDE: %s: device_register error: %d\n",
                         __FUNCTION__, ret);
+                goto out;
+        }
+
+        get_device(&hwif->gendev);
+
+        hwif->portdev = device_create(ide_port_class, &hwif->gendev,
+                                      MKDEV(0, 0), hwif->name);
+        if (IS_ERR(hwif->portdev)) {
+                ret = PTR_ERR(hwif->portdev);
+                device_unregister(&hwif->gendev);
+        }
+        dev_set_drvdata(hwif->portdev, hwif);
+out:
+        return ret;
 }
 
 /**
@@ -1378,6 +1392,58 @@ static void ide_port_cable_detect(ide_hwif_t *hwif)
         }
 }
 
+static ssize_t store_delete_devices(struct device *portdev,
+                                    struct device_attribute *attr,
+                                    const char *buf, size_t n)
+{
+        ide_hwif_t *hwif = dev_get_drvdata(portdev);
+
+        if (strncmp(buf, "1", n))
+                return -EINVAL;
+
+        ide_port_unregister_devices(hwif);
+
+        return n;
+};
+
+static DEVICE_ATTR(delete_devices, S_IWUSR, NULL, store_delete_devices);
+
+static ssize_t store_scan(struct device *portdev,
+                          struct device_attribute *attr,
+                          const char *buf, size_t n)
+{
+        ide_hwif_t *hwif = dev_get_drvdata(portdev);
+
+        if (strncmp(buf, "1", n))
+                return -EINVAL;
+
+        ide_port_unregister_devices(hwif);
+        ide_port_scan(hwif);
+
+        return n;
+};
+
+static DEVICE_ATTR(scan, S_IWUSR, NULL, store_scan);
+
+static struct device_attribute *ide_port_attrs[] = {
+        &dev_attr_delete_devices,
+        &dev_attr_scan,
+        NULL
+};
+
+static int ide_sysfs_register_port(ide_hwif_t *hwif)
+{
+        int i, rc;
+
+        for (i = 0; ide_port_attrs[i]; i++) {
+                rc = device_create_file(hwif->portdev, ide_port_attrs[i]);
+                if (rc)
+                        break;
+        }
+
+        return rc;
+}
+
 int ide_device_add_all(u8 *idx, const struct ide_port_info *d)
 {
         ide_hwif_t *hwif, *mate = NULL;
@@ -1474,6 +1540,7 @@ int ide_device_add_all(u8 *idx, const struct ide_port_info *d)
                 hwif = &ide_hwifs[idx[i]];
 
                 if (hwif->present) {
+                        ide_sysfs_register_port(hwif);
                         ide_proc_register_port(hwif);
                         ide_proc_port_register_devices(hwif);
                 }
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index cb18ba8de22d..d791b1ffb586 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -78,6 +78,8 @@
 /* default maximum number of failures */
 #define IDE_DEFAULT_MAX_FAILURES        1
 
+struct class *ide_port_class;
+
 static const u8 ide_hwif_to_major[] = { IDE0_MAJOR, IDE1_MAJOR,
                                         IDE2_MAJOR, IDE3_MAJOR,
                                         IDE4_MAJOR, IDE5_MAJOR,
@@ -591,6 +593,7 @@ void ide_unregister(unsigned int index, int init_default, int restore)
 
         ide_remove_port_from_hwgroup(hwif);
 
+        device_unregister(hwif->portdev);
         device_unregister(&hwif->gendev);
         wait_for_completion(&hwif->gendev_rel_comp);
 
@@ -1590,6 +1593,13 @@ struct bus_type ide_bus_type = {
 
 EXPORT_SYMBOL_GPL(ide_bus_type);
 
+static void ide_port_class_release(struct device *portdev)
+{
+        ide_hwif_t *hwif = dev_get_drvdata(portdev);
+
+        put_device(&hwif->gendev);
+}
+
 /*
  * This is gets invoked once during initialization, to set *everything* up
  */
@@ -1610,11 +1620,23 @@ static int __init ide_init(void)
                 return ret;
         }
 
+        ide_port_class = class_create(THIS_MODULE, "ide_port");
+        if (IS_ERR(ide_port_class)) {
+                ret = PTR_ERR(ide_port_class);
+                goto out_port_class;
+        }
+        ide_port_class->dev_release = ide_port_class_release;
+
         init_ide_data();
 
         proc_ide_create();
 
         return 0;
+
+out_port_class:
+        bus_unregister(&ide_bus_type);
+
+        return ret;
 }
 
 #ifdef MODULE
@@ -1651,6 +1673,8 @@ void __exit cleanup_module (void)
 
         proc_ide_destroy();
 
+        class_destroy(ide_port_class);
+
         bus_unregister(&ide_bus_type);
 }
 
diff --git a/include/linux/ide.h b/include/linux/ide.h
index e43570a19200..9cebf3054080 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -579,7 +579,9 @@ typedef struct hwif_s {
         unsigned        mmio       : 1; /* host uses MMIO */
         unsigned        straight8  : 1; /* Alan's straight 8 check */
 
-        struct device   gendev;
+        struct device           gendev;
+        struct device           *portdev;
+
         struct completion gendev_rel_comp; /* To deal with device release() */
 
         void            *hwif_data;     /* extra hwif data */
@@ -1275,6 +1277,7 @@ extern struct mutex ide_cfg_mtx;
 #define local_irq_set(flags)    do { local_save_flags((flags)); local_irq_enable_in_hardirq(); } while (0)
 
 extern struct bus_type ide_bus_type;
+extern struct class *ide_port_class;
 
 /* check if CACHE FLUSH (EXT) command is supported (bits defined in ATA-6) */
 #define ide_id_has_flush_cache(id)      ((id)->cfs_enable_2 & 0x3000)