1 files changed, 40 insertions, 9 deletions

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 051b48bd7985..e3f5e7ab7606 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -514,7 +514,7 @@ static int advk_pcie_wait_pio(struct advk_pcie *pcie)
 		udelay(PIO_RETRY_DELAY);
 	}
 
-	dev_err(dev, "config read/write timed out\n");
+	dev_err(dev, "PIO read/write transfer time out\n");
 	return -ETIMEDOUT;
 }
 
@@ -657,6 +657,35 @@ static bool advk_pcie_valid_device(struct advk_pcie *pcie, struct pci_bus *bus,
 	return true;
 }
 
+static bool advk_pcie_pio_is_running(struct advk_pcie *pcie)
+{
+	struct device *dev = &pcie->pdev->dev;
+
+	/*
+	 * Trying to start a new PIO transfer when previous has not completed
+	 * cause External Abort on CPU which results in kernel panic:
+	 *
+	 *     SError Interrupt on CPU0, code 0xbf000002 -- SError
+	 *     Kernel panic - not syncing: Asynchronous SError Interrupt
+	 *
+	 * Functions advk_pcie_rd_conf() and advk_pcie_wr_conf() are protected
+	 * by raw_spin_lock_irqsave() at pci_lock_config() level to prevent
+	 * concurrent calls at the same time. But because PIO transfer may take
+	 * about 1.5s when link is down or card is disconnected, it means that
+	 * advk_pcie_wait_pio() does not always have to wait for completion.
+	 *
+	 * Some versions of ARM Trusted Firmware handles this External Abort at
+	 * EL3 level and mask it to prevent kernel panic. Relevant TF-A commit:
+	 * https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50
+	 */
+	if (advk_readl(pcie, PIO_START)) {
+		dev_err(dev, "Previous PIO read/write transfer is still running\n");
+		return true;
+	}
+
+	return false;
+}
+
 static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 			     int where, int size, u32 *val)
 {
@@ -673,9 +702,10 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 		return pci_bridge_emul_conf_read(&pcie->bridge, where,
 						 size, val);
 
-	/* Start PIO */
-	advk_writel(pcie, 0, PIO_START);
-	advk_writel(pcie, 1, PIO_ISR);
+	if (advk_pcie_pio_is_running(pcie)) {
+		*val = 0xffffffff;
+		return PCIBIOS_SET_FAILED;
+	}
 
 	/* Program the control register */
 	reg = advk_readl(pcie, PIO_CTRL);
@@ -694,7 +724,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 	/* Program the data strobe */
 	advk_writel(pcie, 0xf, PIO_WR_DATA_STRB);
 
-	/* Start the transfer */
+	/* Clear PIO DONE ISR and start the transfer */
+	advk_writel(pcie, 1, PIO_ISR);
 	advk_writel(pcie, 1, PIO_START);
 
 	ret = advk_pcie_wait_pio(pcie);
@@ -734,9 +765,8 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
 	if (where % size)
 		return PCIBIOS_SET_FAILED;
 
-	/* Start PIO */
-	advk_writel(pcie, 0, PIO_START);
-	advk_writel(pcie, 1, PIO_ISR);
+	if (advk_pcie_pio_is_running(pcie))
+		return PCIBIOS_SET_FAILED;
 
 	/* Program the control register */
 	reg = advk_readl(pcie, PIO_CTRL);
@@ -763,7 +793,8 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
 	/* Program the data strobe */
 	advk_writel(pcie, data_strobe, PIO_WR_DATA_STRB);
 
-	/* Start the transfer */
+	/* Clear PIO DONE ISR and start the transfer */
+	advk_writel(pcie, 1, PIO_ISR);
 	advk_writel(pcie, 1, PIO_START);
 
 	ret = advk_pcie_wait_pio(pcie);