ipmi: Handle BMCs that don't allow clearing the rcv irq bit

Some BMCs don't let you clear the receive irq bit in the global
enables.  This is kind of silly, but they give an error if you
try to clear it.  Compensate for this by detecting the situation
and working around it.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Tested-by: Thomas D <whissi@whissi.de>
Reviewed-by: Thomas D <whissi@whissi.de>

drivers/char/ipmi/ipmi_si_intf.c

@@ -262,6 +262,11 @@ struct smi_info {
 	 */
 	bool supports_event_msg_buff;
 
+	/*
+	 * Can we clear the global enables receive irq bit?
+	 */
+	bool cannot_clear_recv_irq_bit;
+
 	/*
 	 * Did we get an attention that we did not handle?
 	 */
@@ -461,6 +466,9 @@ static void smi_mod_timer(struct smi_info *smi_info, unsigned long new_val)
  * allocate messages, we just leave them in the BMC and run the system
  * polled until we can allocate some memory.  Once we have some
  * memory, we will re-enable the interrupt.
+ *
+ * Note that we cannot just use disable_irq(), since the interrupt may
+ * be shared.
  */
 static inline bool disable_si_irq(struct smi_info *smi_info)
 {
@@ -549,20 +557,15 @@ static u8 current_global_enables(struct smi_info *smi_info, u8 base,
 
 	if (smi_info->supports_event_msg_buff)
 		enables |= IPMI_BMC_EVT_MSG_BUFF;
-	else
-		enables &= ~IPMI_BMC_EVT_MSG_BUFF;
 
-	if (smi_info->irq && !smi_info->interrupt_disabled)
+	if ((smi_info->irq && !smi_info->interrupt_disabled) ||
+	    smi_info->cannot_clear_recv_irq_bit)
 		enables |= IPMI_BMC_RCV_MSG_INTR;
-	else
-		enables &= ~IPMI_BMC_RCV_MSG_INTR;
 
 	if (smi_info->supports_event_msg_buff &&
 	    smi_info->irq && !smi_info->interrupt_disabled)
 
 		enables |= IPMI_BMC_EVT_MSG_INTR;
-	else
-		enables &= ~IPMI_BMC_EVT_MSG_INTR;
 
 	*irq_on = enables & (IPMI_BMC_EVT_MSG_INTR | IPMI_BMC_RCV_MSG_INTR);
 
@@ -2900,6 +2903,96 @@ static int try_get_dev_id(struct smi_info *smi_info)
 	return rv;
 }
 
+/*
+ * Some BMCs do not support clearing the receive irq bit in the global
+ * enables (even if they don't support interrupts on the BMC).  Check
+ * for this and handle it properly.
+ */
+static void check_clr_rcv_irq(struct smi_info *smi_info)
+{
+	unsigned char         msg[3];
+	unsigned char         *resp;
+	unsigned long         resp_len;
+	int                   rv;
+
+	resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
+	if (!resp) {
+		printk(KERN_WARNING PFX "Out of memory allocating response for"
+		       " global enables command, cannot check recv irq bit"
+		       " handling.\n");
+		return;
+	}
+
+	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
+	msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;
+	smi_info->handlers->start_transaction(smi_info->si_sm, msg, 2);
+
+	rv = wait_for_msg_done(smi_info);
+	if (rv) {
+		printk(KERN_WARNING PFX "Error getting response from get"
+		       " global enables command, cannot check recv irq bit"
+		       " handling.\n");
+		goto out;
+	}
+
+	resp_len = smi_info->handlers->get_result(smi_info->si_sm,
+						  resp, IPMI_MAX_MSG_LENGTH);
+
+	if (resp_len < 4 ||
+			resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
+			resp[1] != IPMI_GET_BMC_GLOBAL_ENABLES_CMD   ||
+			resp[2] != 0) {
+		printk(KERN_WARNING PFX "Invalid return from get global"
+		       " enables command, cannot check recv irq bit"
+		       " handling.\n");
+		rv = -EINVAL;
+		goto out;
+	}
+
+	if ((resp[3] & IPMI_BMC_RCV_MSG_INTR) == 0)
+		/* Already clear, should work ok. */
+		goto out;
+
+	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
+	msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
+	msg[2] = resp[3] & ~IPMI_BMC_RCV_MSG_INTR;
+	smi_info->handlers->start_transaction(smi_info->si_sm, msg, 3);
+
+	rv = wait_for_msg_done(smi_info);
+	if (rv) {
+		printk(KERN_WARNING PFX "Error getting response from set"
+		       " global enables command, cannot check recv irq bit"
+		       " handling.\n");
+		goto out;
+	}
+
+	resp_len = smi_info->handlers->get_result(smi_info->si_sm,
+						  resp, IPMI_MAX_MSG_LENGTH);
+
+	if (resp_len < 3 ||
+			resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
+			resp[1] != IPMI_SET_BMC_GLOBAL_ENABLES_CMD) {
+		printk(KERN_WARNING PFX "Invalid return from get global"
+		       " enables command, cannot check recv irq bit"
+		       " handling.\n");
+		rv = -EINVAL;
+		goto out;
+	}
+
+	if (resp[2] != 0) {
+		/*
+		 * An error when setting the event buffer bit means
+		 * clearing the bit is not supported.
+		 */
+		printk(KERN_WARNING PFX "The BMC does not support clearing"
+		       " the recv irq bit, compensating, but the BMC needs to"
+		       " be fixed.\n");
+		smi_info->cannot_clear_recv_irq_bit = true;
+	}
+ out:
+	kfree(resp);
+}
+
 static int try_enable_event_buffer(struct smi_info *smi_info)
 {
 	unsigned char         msg[3];
@@ -3395,6 +3488,8 @@ static int try_smi_init(struct smi_info *new_smi)
 		goto out_err;
 	}
 
+	check_clr_rcv_irq(new_smi);
+
 	setup_oem_data_handler(new_smi);
 	setup_xaction_handlers(new_smi);