linux-kernel - [PATCH 41/42] PCI: pci-bridge-emul: add support for PCIe extended capabilities

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Date:   Thu,  6 May 2021 17:31:52 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Russell King <rmk+kernel@...linux.org.uk>,
        Marek Behún <kabel@...nel.org>,
        Remi Pommarel <repk@...plefau.lt>, Xogium <contact@...ium.me>,
        Tomasz Maciej Nowak <tmn505@...il.com>,
        Marc Zyngier <maz@...nel.org>, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 41/42] PCI: pci-bridge-emul: add support for PCIe extended capabilities

From: Russell King <rmk+kernel@...linux.org.uk>

Add support for PCIe extended capabilities, which we just redirect to the
emulating driver.

Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
---
 drivers/pci/pci-bridge-emul.c | 52 +++++++++++++++++++++++++----------
 drivers/pci/pci-bridge-emul.h | 15 ++++++++++
 2 files changed, 53 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 63959e4b188a..236036fdeaa2 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -385,10 +385,16 @@ int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
 		read_op = bridge->ops->read_pcie;
 		cfgspace = (__le32 *) &bridge->pcie_conf;
 		behavior = bridge->pcie_cap_regs_behavior;
-	} else {
-		/* Beyond our PCIe space */
+	} else if (reg < PCI_CFG_SPACE_SIZE) {
+		/* Rest of PCI space not implemented */
 		*value = 0;
 		return PCIBIOS_SUCCESSFUL;
+	} else {
+		/* PCIe extended capability space */
+		reg -= PCI_CFG_SPACE_SIZE;
+		read_op = bridge->ops->read_ext;
+		cfgspace = NULL;
+		behavior = NULL;
 	}
 
 	if (read_op)
@@ -396,15 +402,20 @@ int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
 	else
 		ret = PCI_BRIDGE_EMUL_NOT_HANDLED;
 
-	if (ret == PCI_BRIDGE_EMUL_NOT_HANDLED)
-		*value = le32_to_cpu(cfgspace[reg / 4]);
+	if (ret == PCI_BRIDGE_EMUL_NOT_HANDLED) {
+		if (cfgspace)
+			*value = le32_to_cpu(cfgspace[reg / 4]);
+		else
+			*value = 0;
+	}
 
 	/*
 	 * Make sure we never return any reserved bit with a value
 	 * different from 0.
 	 */
-	*value &= behavior[reg / 4].ro | behavior[reg / 4].rw |
-		  behavior[reg / 4].w1c;
+	if (behavior)
+		*value &= behavior[reg / 4].ro | behavior[reg / 4].rw |
+			  behavior[reg / 4].w1c;
 
 	if (size == 1)
 		*value = (*value >> (8 * (where & 3))) & 0xff;
@@ -450,8 +461,15 @@ int pci_bridge_emul_conf_write(struct pci_bridge_emul *bridge, int where,
 		write_op = bridge->ops->write_pcie;
 		cfgspace = (__le32 *) &bridge->pcie_conf;
 		behavior = bridge->pcie_cap_regs_behavior;
-	} else {
+	} else if (reg < PCI_CFG_SPACE_SIZE) {
+		/* Rest of PCI space not implemented */
 		return PCIBIOS_SUCCESSFUL;
+	} else {
+		/* PCIe extended capability space */
+		reg -= PCI_CFG_SPACE_SIZE;
+		write_op = bridge->ops->write_ext;
+		cfgspace = NULL;
+		behavior = NULL;
 	}
 
 	shift = (where & 0x3) * 8;
@@ -465,16 +483,22 @@ int pci_bridge_emul_conf_write(struct pci_bridge_emul *bridge, int where,
 	else
 		return PCIBIOS_BAD_REGISTER_NUMBER;
 
-	/* Keep all bits, except the RW bits */
-	new = old & (~mask | ~behavior[reg / 4].rw);
+	if (behavior) {
+		/* Keep all bits, except the RW bits */
+		new = old & (~mask | ~behavior[reg / 4].rw);
 
-	/* Update the value of the RW bits */
-	new |= (value << shift) & (behavior[reg / 4].rw & mask);
+		/* Update the value of the RW bits */
+		new |= (value << shift) & (behavior[reg / 4].rw & mask);
 
-	/* Clear the W1C bits */
-	new &= ~((value << shift) & (behavior[reg / 4].w1c & mask));
+		/* Clear the W1C bits */
+		new &= ~((value << shift) & (behavior[reg / 4].w1c & mask));
+	} else {
+		new = old & ~mask;
+		new |= (value << shift) & mask;
+	}
 
-	cfgspace[reg / 4] = cpu_to_le32(new);
+	if (cfgspace)
+		cfgspace[reg / 4] = cpu_to_le32(new);
 
 	if (write_op)
 		write_op(bridge, reg, old, new, mask);
diff --git a/drivers/pci/pci-bridge-emul.h b/drivers/pci/pci-bridge-emul.h
index 49bbd37ee318..2552ab660b08 100644
--- a/drivers/pci/pci-bridge-emul.h
+++ b/drivers/pci/pci-bridge-emul.h
@@ -90,6 +90,14 @@ struct pci_bridge_emul_ops {
 	 */
 	pci_bridge_emul_read_status_t (*read_pcie)(struct pci_bridge_emul *bridge,
 						   int reg, u32 *value);
+
+	/*
+	 * Same as ->read_base(), except it is for reading from the
+	 * PCIe extended capability configuration space.
+	 */
+	pci_bridge_emul_read_status_t (*read_ext)(struct pci_bridge_emul *bridge,
+						  int reg, u32 *value);
+
 	/*
 	 * Called when writing to the regular PCI bridge configuration
 	 * space. old is the current value, new is the new value being
@@ -105,6 +113,13 @@ struct pci_bridge_emul_ops {
 	 */
 	void (*write_pcie)(struct pci_bridge_emul *bridge, int reg,
 			   u32 old, u32 new, u32 mask);
+
+	/*
+	 * Same as ->write_base(), except it is for writing from the
+	 * PCIe extended capability configuration space.
+	 */
+	void (*write_ext)(struct pci_bridge_emul *bridge, int reg,
+			  u32 old, u32 new, u32 mask);
 };
 
 struct pci_bridge_reg_behavior;
-- 
2.20.1