ipmi:bt-bmc: Fix error handling and status check

If the function platform_get_irq() failed, the negative value
returned will not be detected here. So fix error handling in
bt_bmc_config_irq(). And in the function bt_bmc_probe(),
when get irq failed, it will print error message. So use
platform_get_irq_optional() to simplify code. Finally in the
function bt_bmc_remove() should make the right status check
if get irq failed.
Signed-off-by: Shengju Zhang <zhangshengju@cmss.chinamobile.com>
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Message-Id: <20200505102906.17196-1-tangbin@cmss.chinamobile.com>
[Also set bt_bmc->irq to a negative value if devm_request_irq() fails.]
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/bt-bmc.c

@@ -399,15 +399,15 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 	struct device *dev = &pdev->dev;
 	int rc;
 
-	bt_bmc->irq = platform_get_irq(pdev, 0);
-	if (!bt_bmc->irq)
-		return -ENODEV;
+	bt_bmc->irq = platform_get_irq_optional(pdev, 0);
+	if (bt_bmc->irq < 0)
+		return bt_bmc->irq;
 
 	rc = devm_request_irq(dev, bt_bmc->irq, bt_bmc_irq, IRQF_SHARED,
 			      DEVICE_NAME, bt_bmc);
 	if (rc < 0) {
 		dev_warn(dev, "Unable to request IRQ %d\n", bt_bmc->irq);
-		bt_bmc->irq = 0;
+		bt_bmc->irq = rc;
 		return rc;
 	}
 
@@ -474,7 +474,7 @@ static int bt_bmc_probe(struct platform_device *pdev)
 
 	bt_bmc_config_irq(bt_bmc, pdev);
 
-	if (bt_bmc->irq) {
+	if (bt_bmc->irq >= 0) {
 		dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
 	} else {
 		dev_info(dev, "No IRQ; using timer\n");
@@ -500,7 +500,7 @@ static int bt_bmc_remove(struct platform_device *pdev)
 	struct bt_bmc *bt_bmc = dev_get_drvdata(&pdev->dev);
 
 	misc_deregister(&bt_bmc->miscdev);
-	if (!bt_bmc->irq)
+	if (bt_bmc->irq < 0)
 		del_timer_sync(&bt_bmc->poll_timer);
 	return 0;
 }