[PATCH] IPMI: system interface hotplug

Add the ability to hot add and remove interfaces in the ipmi_si driver.  Any
users who have the device open will get errors if they try to send a message.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/IPMI.txt

@@ -365,6 +365,7 @@ You can change this at module load time (for a module) with:
        regshifts=<shift1>,<shift2>,...
        slave_addrs=<addr1>,<addr2>,...
        force_kipmid=<enable1>,<enable2>,...
+       unload_when_empty=[0|1]
 
 Each of these except si_trydefaults is a list, the first item for the
 first interface, second item for the second interface, etc.
@@ -416,6 +417,11 @@ by the driver, but systems with broken interrupts might need an enable,
 or users that don't want the daemon (don't need the performance, don't
 want the CPU hit) can disable it.
 
+If unload_when_empty is set to 1, the driver will be unloaded if it
+doesn't find any interfaces or all the interfaces fail to work.  The
+default is one.  Setting to 0 is useful with the hotmod, but is
+obviously only useful for modules.
+
 When compiled into the kernel, the parameters can be specified on the
 kernel command line as:
 
@@ -441,6 +447,25 @@ have high-res timers enabled in the kernel and you don't have
 interrupts enabled, the driver will run VERY slowly.  Don't blame me,
 these interfaces suck.
 
+The driver supports a hot add and remove of interfaces.  This way,
+interfaces can be added or removed after the kernel is up and running.
+This is done using /sys/modules/ipmi_si/hotmod, which is a write-only
+parameter.  You write a string to this interface.  The string has the
+format:
+   <op1>[:op2[:op3...]]
+The "op"s are:
+   add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
+You can specify more than one interface on the line.  The "opt"s are:
+   rsp=<regspacing>
+   rsi=<regsize>
+   rsh=<regshift>
+   irq=<irq>
+   ipmb=<ipmb slave addr>
+and these have the same meanings as discussed above.  Note that you
+can also use this on the kernel command line for a more compact format
+for specifying an interface.  Note that when removing an interface,
+only the first three parameters (si type, address type, and address)
+are used for the comparison.  Any options are ignored for removing.
 
 The SMBus Driver
 ----------------