1 files changed, 67 insertions, 4 deletions

diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 176f1751237..4462b113ba3 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -295,6 +295,9 @@ struct smi_info {
 static int force_kipmid[SI_MAX_PARMS];
 static int num_force_kipmid;
 
+static unsigned int kipmid_max_busy_us[SI_MAX_PARMS];
+static int num_max_busy_us;
+
 static int unload_when_empty = 1;
 
 static int try_smi_init(struct smi_info *smi);
@@ -925,23 +928,77 @@ static void set_run_to_completion(void *send_info, int i_run_to_completion)
         }
 }
 
+/*
+ * Use -1 in the nsec value of the busy waiting timespec to tell that
+ * we are spinning in kipmid looking for something and not delaying
+ * between checks
+ */
+static inline void ipmi_si_set_not_busy(struct timespec *ts)
+{
+        ts->tv_nsec = -1;
+}
+static inline int ipmi_si_is_busy(struct timespec *ts)
+{
+        return ts->tv_nsec != -1;
+}
+
+static int ipmi_thread_busy_wait(enum si_sm_result smi_result,
+                                 const struct smi_info *smi_info,
+                                 struct timespec *busy_until)
+{
+        unsigned int max_busy_us = 0;
+
+        if (smi_info->intf_num < num_max_busy_us)
+                max_busy_us = kipmid_max_busy_us[smi_info->intf_num];
+        if (max_busy_us == 0 || smi_result != SI_SM_CALL_WITH_DELAY)
+                ipmi_si_set_not_busy(busy_until);
+        else if (!ipmi_si_is_busy(busy_until)) {
+                getnstimeofday(busy_until);
+                timespec_add_ns(busy_until, max_busy_us*NSEC_PER_USEC);
+        } else {
+                struct timespec now;
+                getnstimeofday(&now);
+                if (unlikely(timespec_compare(&now, busy_until) > 0)) {
+                        ipmi_si_set_not_busy(busy_until);
+                        return 0;
+                }
+        }
+        return 1;
+}
+
+
+/*
+ * A busy-waiting loop for speeding up IPMI operation.
+ *
+ * Lousy hardware makes this hard.  This is only enabled for systems
+ * that are not BT and do not have interrupts.  It starts spinning
+ * when an operation is complete or until max_busy tells it to stop
+ * (if that is enabled).  See the paragraph on kimid_max_busy_us in
+ * Documentation/IPMI.txt for details.
+ */
 static int ipmi_thread(void *data)
 {
         struct smi_info *smi_info = data;
         unsigned long flags;
         enum si_sm_result smi_result;
+        struct timespec busy_until;
 
+        ipmi_si_set_not_busy(&busy_until);
         set_user_nice(current, 19);
         while (!kthread_should_stop()) {
+                int busy_wait;
+
                 spin_lock_irqsave(&(smi_info->si_lock), flags);
                 smi_result = smi_event_handler(smi_info, 0);
                 spin_unlock_irqrestore(&(smi_info->si_lock), flags);
+                busy_wait = ipmi_thread_busy_wait(smi_result, smi_info,
+                                                  &busy_until);
                 if (smi_result == SI_SM_CALL_WITHOUT_DELAY)
                         ; /* do nothing */
-                else if (smi_result == SI_SM_CALL_WITH_DELAY)
+                else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait)
                         schedule();
                 else
-                        schedule_timeout_interruptible(1);
+                        schedule_timeout_interruptible(0);
         }
         return 0;
 }
@@ -1144,7 +1201,7 @@ static int           regsizes[SI_MAX_PARMS];
 static unsigned int num_regsizes;
 static int           regshifts[SI_MAX_PARMS];
 static unsigned int num_regshifts;
-static int slave_addrs[SI_MAX_PARMS];
+static int slave_addrs[SI_MAX_PARMS]; /* Leaving 0 chooses the default value */
 static unsigned int num_slave_addrs;
 
 #define IPMI_IO_ADDR_SPACE  0
@@ -1212,6 +1269,11 @@ module_param(unload_when_empty, int, 0);
 MODULE_PARM_DESC(unload_when_empty, "Unload the module if no interfaces are"
                  " specified or found, default is 1.  Setting to 0"
                  " is useful for hot add of devices using hotmod.");
+module_param_array(kipmid_max_busy_us, uint, &num_max_busy_us, 0644);
+MODULE_PARM_DESC(kipmid_max_busy_us,
+                 "Max time (in microseconds) to busy-wait for IPMI data before"
+                 " sleeping. 0 (default) means to wait forever. Set to 100-500"
+                 " if kipmid is using up a lot of CPU time.");
 
 
 static void std_irq_cleanup(struct smi_info *info)
@@ -1607,7 +1669,7 @@ static int hotmod_handler(const char *val, struct kernel_param *kp)
                 regsize = 1;
                 regshift = 0;
                 irq = 0;
-                ipmb = 0x20;
+                ipmb = 0; /* Choose the default if not specified */
 
                 next = strchr(curr, ':');
                 if (next) {
@@ -1799,6 +1861,7 @@ static __devinit void hardcode_find_bmc(void)
                 info->irq = irqs[i];
                 if (info->irq)
                         info->irq_setup = std_irq_setup;
+                info->slave_addr = slave_addrs[i];
 
                 try_smi_init(info);
         }