linux-kernel - [PATCH v3] PCI: uniphier: Serialize INTx masking/unmasking and fix the bit operation

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Message-Id: <1631924579-24567-1-git-send-email-hayashi.kunihiko@socionext.com>
Date:   Sat, 18 Sep 2021 09:22:59 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Pali Rohár <pali@...nel.org>,
        Marc Zyngier <maz@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Subject: [PATCH v3] PCI: uniphier: Serialize INTx masking/unmasking and fix the bit operation

The condition register PCI_RCV_INTX is used in irq_mask() and irq_unmask()
callbacks. Accesses to register can occur at the same time without a lock.
Add a lock into each callback to prevent the issue.

And INTX mask and unmask fields in PCL_RCV_INTX register should only be
set/reset for each bit. Clearing by PCL_RCV_INTX_ALL_MASK should be
removed.

INTX status fields in PCL_RCV_INTX register only indicates each INTX
interrupt status, so the handler can't clear by writing 1 to the field.
The status is expected to be cleared by the interrupt origin.
The ack function has no meaning, so should remove it.

Fixes: 7e6d5cd88a6f ("PCI: uniphier: Add UniPhier PCIe host controller support")
Suggested-by: Pali Rohár <pali@...nel.org>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Acked-by: Pali Rohár <pali@...nel.org>
Acked-by: Marc Zyngier <maz@...nel.org>
---
Changes in v3:
- Squash two fix patches into one
- Add Acked-by: line

Changes in v2:
- Add Acked-by: line to the first patch
- Add a fix patch for bit operation

---
 drivers/pci/controller/dwc/pcie-uniphier.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-uniphier.c b/drivers/pci/controller/dwc/pcie-uniphier.c
index d95df02..d35501b 100644
--- a/drivers/pci/controller/dwc/pcie-uniphier.c
+++ b/drivers/pci/controller/dwc/pcie-uniphier.c
@@ -194,30 +194,21 @@ static void uniphier_pcie_irq_enable(struct uniphier_pcie_priv *priv)
 	writel(PCL_RCV_INTX_ALL_ENABLE, priv->base + PCL_RCV_INTX);
 }
 
-static void uniphier_pcie_irq_ack(struct irq_data *d)
-{
-	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
-	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
-	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
-	u32 val;
-
-	val = readl(priv->base + PCL_RCV_INTX);
-	val &= ~PCL_RCV_INTX_ALL_STATUS;
-	val |= BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_STATUS_SHIFT);
-	writel(val, priv->base + PCL_RCV_INTX);
-}
-
 static void uniphier_pcie_irq_mask(struct irq_data *d)
 {
 	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
+	unsigned long flags;
 	u32 val;
 
+	raw_spin_lock_irqsave(&pp->lock, flags);
+
 	val = readl(priv->base + PCL_RCV_INTX);
-	val &= ~PCL_RCV_INTX_ALL_MASK;
 	val |= BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_MASK_SHIFT);
 	writel(val, priv->base + PCL_RCV_INTX);
+
+	raw_spin_unlock_irqrestore(&pp->lock, flags);
 }
 
 static void uniphier_pcie_irq_unmask(struct irq_data *d)
@@ -225,17 +216,20 @@ static void uniphier_pcie_irq_unmask(struct irq_data *d)
 	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
+	unsigned long flags;
 	u32 val;
 
+	raw_spin_lock_irqsave(&pp->lock, flags);
+
 	val = readl(priv->base + PCL_RCV_INTX);
-	val &= ~PCL_RCV_INTX_ALL_MASK;
 	val &= ~BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_MASK_SHIFT);
 	writel(val, priv->base + PCL_RCV_INTX);
+
+	raw_spin_unlock_irqrestore(&pp->lock, flags);
 }
 
 static struct irq_chip uniphier_pcie_irq_chip = {
 	.name = "PCI",
-	.irq_ack = uniphier_pcie_irq_ack,
 	.irq_mask = uniphier_pcie_irq_mask,
 	.irq_unmask = uniphier_pcie_irq_unmask,
 };
-- 
2.7.4