[PATCH 1/1] fpga: dfl: afu: harden port enable logic

[Russ Weight]

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

Signed-off-by: Russ Weight <russell.h.wei...@intel.com>
---
 drivers/fpga/dfl-afu-error.c |  2 +-
 drivers/fpga/dfl-afu-main.c  | 29 +++++++++++++++++++++--------
 drivers/fpga/dfl-afu.h       |  2 +-
 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c
index c4691187cca9..0806532a3e9f 100644
--- a/drivers/fpga/dfl-afu-error.c
+++ b/drivers/fpga/dfl-afu-error.c
@@ -103,7 +103,7 @@ static int afu_port_err_clear(struct device *dev, u64 err)
        __afu_port_err_mask(dev, false);
 
        /* Enable the Port by clear the reset */
-       __afu_port_enable(pdev);
+       ret = __afu_port_enable(pdev);
 
 done:
        mutex_unlock(&pdata->lock);
diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 753cda4b2568..f73b06cdf13c 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
@@ -111,7 +124,7 @@ static int __port_reset(struct platform_device *pdev)
 
        ret = __afu_port_disable(pdev);
        if (!ret)
-               __afu_port_enable(pdev);
+               ret = __afu_port_enable(pdev);
 
        return ret;
 }
@@ -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);
diff --git a/drivers/fpga/dfl-afu.h b/drivers/fpga/dfl-afu.h
index 576e94960086..e5020e2b1f3d 100644
--- a/drivers/fpga/dfl-afu.h
+++ b/drivers/fpga/dfl-afu.h
@@ -80,7 +80,7 @@ struct dfl_afu {
 };
 
 /* hold pdata->lock when call __afu_port_enable/disable */
-void __afu_port_enable(struct platform_device *pdev);
+int __afu_port_enable(struct platform_device *pdev);
 int __afu_port_disable(struct platform_device *pdev);
 
 void afu_mmio_region_init(struct dfl_feature_platform_data *pdata);
-- 
2.17.1