IPMI: Convert system interface defines to an enum

Convert the #defines for statistics into an enum in the IPMI system interface
and remove the unused timeout_restart statistic. And comment what these
statistics mean.

Signed-off-by: Corey Minyard <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/ipmi/ipmi_si_intf.c

···
 /*
  * Indexes into stats[] in smi_info below.
  */
+enum si_stat_indexes {
+	/*
+	 * Number of times the driver requested a timer while an operation
+	 * was in progress.
+	 */
+	SI_STAT_short_timeouts = 0,
 
-#define SI_STAT_short_timeouts		0
-#define SI_STAT_long_timeouts		1
-#define SI_STAT_timeout_restarts	2
-#define SI_STAT_idles			3
-#define SI_STAT_interrupts		4
-#define SI_STAT_attentions		5
-#define SI_STAT_flag_fetches		6
-#define SI_STAT_hosed_count		7
-#define SI_STAT_complete_transactions	8
-#define SI_STAT_events			9
-#define SI_STAT_watchdog_pretimeouts	10
-#define SI_STAT_incoming_messages	11
+	/*
+	 * Number of times the driver requested a timer while nothing was in
+	 * progress.
+	 */
+	SI_STAT_long_timeouts,
 
-/* If you add a stat, you must update this value. */
-#define SI_NUM_STATS			12
+	/* Number of times the interface was idle while being polled. */
+	SI_STAT_idles,
+
+	/* Number of interrupts the driver handled. */
+	SI_STAT_interrupts,
+
+	/* Number of time the driver got an ATTN from the hardware. */
+	SI_STAT_attentions,
+
+	/* Number of times the driver requested flags from the hardware. */
+	SI_STAT_flag_fetches,
+
+	/* Number of times the hardware didn't follow the state machine. */
+	SI_STAT_hosed_count,
+
+	/* Number of completed messages. */
+	SI_STAT_complete_transactions,
+
+	/* Number of IPMI events received from the hardware. */
+	SI_STAT_events,
+
+	/* Number of watchdog pretimeouts. */
+	SI_STAT_watchdog_pretimeouts,
+
+	/* Number of asyncronous messages received. */
+	SI_STAT_incoming_messages,
+
+
+	/* This *must* remain last, add new values above this. */
+	SI_NUM_STATS
+};
 
 struct smi_info
 {
···
 		       smi_get_stat(smi, short_timeouts));
 	out += sprintf(out, "long_timeouts:         %u\n",
 		       smi_get_stat(smi, long_timeouts));
-	out += sprintf(out, "timeout_restarts:      %u\n",
-		       smi_get_stat(smi, timeout_restarts));
 	out += sprintf(out, "idles:                 %u\n",
 		       smi_get_stat(smi, idles));
 	out += sprintf(out, "interrupts:            %u\n",