ipmi: Add a reference from BMC devices to their interfaces

In an upcoming change, we'll want to grab a reference to the ipmi_smi_t
from a struct bmc_device. This change adds a pointer to allow this.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

Reworked to support multiple interfaces on a BMC.
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -265,6 +265,7 @@ struct ipmi_proc_entry {
 struct bmc_device {
 	struct platform_device pdev;
 	struct ipmi_device_id  id;
+	struct list_head       intfs;
 	unsigned char          guid[16];
 	int                    guid_set;
 	char                   name[16];
@@ -404,6 +405,7 @@ struct ipmi_smi {
 
 	struct bmc_device *bmc;
 	bool bmc_registered;
+	struct list_head bmc_link;
 	char *my_dev_name;
 
 	/*
@@ -2616,6 +2618,8 @@ static void ipmi_bmc_unregister(ipmi_smi_t intf)
 	intf->my_dev_name = NULL;
 
 	mutex_lock(&ipmidriver_mutex);
+	list_del(&intf->bmc_link);
+	intf->bmc = NULL;
 	kref_put(&bmc->usecount, cleanup_bmc_device);
 	mutex_unlock(&ipmidriver_mutex);
 	intf->bmc_registered = false;
@@ -2646,7 +2650,10 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
 	 */
 	if (old_bmc) {
 		kfree(bmc);
+		mutex_lock(&ipmidriver_mutex);
 		intf->bmc = old_bmc;
+		list_add_tail(&intf->bmc_link, &bmc->intfs);
+		mutex_unlock(&ipmidriver_mutex);
 		bmc = old_bmc;
 
 		printk(KERN_INFO
@@ -2697,6 +2704,7 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
 		kref_init(&bmc->usecount);
 
 		rv = platform_device_register(&bmc->pdev);
+		list_add_tail(&intf->bmc_link, &bmc->intfs);
 		mutex_unlock(&ipmidriver_mutex);
 		if (rv) {
 			printk(KERN_ERR
@@ -2761,6 +2769,7 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
 
 out_put_bmc:
 	mutex_lock(&ipmidriver_mutex);
+	list_del(&intf->bmc_link);
 	intf->bmc = NULL;
 	kref_put(&bmc->usecount, cleanup_bmc_device);
 	mutex_unlock(&ipmidriver_mutex);
@@ -2768,6 +2777,7 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
 
 out_list_del:
 	mutex_lock(&ipmidriver_mutex);
+	list_del(&intf->bmc_link);
 	intf->bmc = NULL;
 	mutex_unlock(&ipmidriver_mutex);
 	put_device(&bmc->pdev.dev);
@@ -2990,6 +3000,7 @@ int ipmi_register_smi(const struct ipmi_smi_handlers *handlers,
 		kfree(intf);
 		return -ENOMEM;
 	}
+	INIT_LIST_HEAD(&intf->bmc->intfs);
 	intf->intf_num = -1; /* Mark it invalid for now. */
 	kref_init(&intf->refcount);
 	intf->bmc->id = *device_id;