fpga: dfl: afu: harden port enable logic

Port enable is not complete until ACK = 0. Change
__afu_port_enable() to guarantee that the enable process
is complete by polling for ACK == 0.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Reviewed-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Acked-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>

1 files changed, 24 insertions, 11 deletions

diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 753cda4b2568..7f621e96d3b8 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c
@@ -21,6 +21,9 @@
 
 #include "dfl-afu.h"
 
+#define RST_POLL_INVL 10 /* us */
+#define RST_POLL_TIMEOUT 1000 /* us */
+
 /**
  * __afu_port_enable - enable a port by clear reset
  * @pdev: port platform device.
@@ -32,7 +35,7 @@
  *
  * The caller needs to hold lock for protection.
  */
-void __afu_port_enable(struct platform_device *pdev)
+int __afu_port_enable(struct platform_device *pdev)
 {
 	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	void __iomem *base;
@@ -41,7 +44,7 @@ void __afu_port_enable(struct platform_device *pdev)
 	WARN_ON(!pdata->disable_count);
 
 	if (--pdata->disable_count != 0)
-		return;
+		return 0;
 
 	base = dfl_get_feature_ioaddr_by_id(&pdev->dev, PORT_FEATURE_ID_HEADER);
 
@@ -49,10 +52,20 @@ void __afu_port_enable(struct platform_device *pdev)
 	v = readq(base + PORT_HDR_CTRL);
 	v &= ~PORT_CTRL_SFTRST;
 	writeq(v, base + PORT_HDR_CTRL);
-}
 
-#define RST_POLL_INVL 10 /* us */
-#define RST_POLL_TIMEOUT 1000 /* us */
+	/*
+	 * HW clears the ack bit to indicate that the port is fully out
+	 * of reset.
+	 */
+	if (readq_poll_timeout(base + PORT_HDR_CTRL, v,
+			       !(v & PORT_CTRL_SFTRST_ACK),
+			       RST_POLL_INVL, RST_POLL_TIMEOUT)) {
+		dev_err(&pdev->dev, "timeout, failure to enable device\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
 
 /**
  * __afu_port_disable - disable a port by hold reset
@@ -86,7 +99,7 @@ int __afu_port_disable(struct platform_device *pdev)
 	if (readq_poll_timeout(base + PORT_HDR_CTRL, v,
 			       v & PORT_CTRL_SFTRST_ACK,
 			       RST_POLL_INVL, RST_POLL_TIMEOUT)) {
-		dev_err(&pdev->dev, "timeout, fail to reset device\n");
+		dev_err(&pdev->dev, "timeout, failure to disable device\n");
 		return -ETIMEDOUT;
 	}
 
@@ -110,10 +123,10 @@ static int __port_reset(struct platform_device *pdev)
 	int ret;
 
 	ret = __afu_port_disable(pdev);
-	if (!ret)
-		__afu_port_enable(pdev);
+	if (ret)
+		return ret;
 
-	return ret;
+	return __afu_port_enable(pdev);
 }
 
 static int port_reset(struct platform_device *pdev)
@@ -872,11 +885,11 @@ static int afu_dev_destroy(struct platform_device *pdev)
 static int port_enable_set(struct platform_device *pdev, bool enable)
 {
 	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
-	int ret = 0;
+	int ret;
 
 	mutex_lock(&pdata->lock);
 	if (enable)
-		__afu_port_enable(pdev);
+		ret = __afu_port_enable(pdev);
 	else
 		ret = __afu_port_disable(pdev);
 	mutex_unlock(&pdata->lock);