[PATCH 2/2 V5] irqchip: gicv2m: Add support for multiple MSI for ARM64 GICv2m

[<suravee.suthikulpanit@amd.com>]

From: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>

This patch extend GICv2m MSI to support multiple MSI in ARM64.

This requires the common arch_setup_msi_irqs() to be overwriten
with ARM64 version which does not return 1 for PCI_CAP_ID_MSI and
nvec > 1.

Cc: Mark Rutland <Mark.Rutland@arm.com>
Cc: Marc Zyngier <Marc.Zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Will Deacon <Will.Deacon@arm.com>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
 arch/arm64/kernel/Makefile    |  1 +
 arch/arm64/kernel/msi.c       | 41 ++++++++++++++++++++
 drivers/irqchip/irq-gic-v2m.c | 87 ++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 119 insertions(+), 10 deletions(-)
 create mode 100644 arch/arm64/kernel/msi.c

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index df7ef87..a921c42 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -29,6 +29,7 @@ arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND)	+= sleep.o suspend.o
 arm64-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
 arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
+arm64-obj-$(CONFIG_PCI_MSI)		+= msi.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
diff --git a/arch/arm64/kernel/msi.c b/arch/arm64/kernel/msi.c
new file mode 100644
index 0000000..a295862
--- /dev/null
+++ b/arch/arm64/kernel/msi.c
@@ -0,0 +1,41 @@
+/*
+ * ARM64 architectural MSI implemention
+ *
+ * Support for Message Signalelled Interrupts for systems that
+ * implement ARM Generic Interrupt Controller: GICv2m.
+ *
+ * Copyright (C) 2014 Advanced Micro Devices, Inc.
+ * Authors: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/irq.h>
+#include <linux/msi.h>
+#include <linux/pci.h>
+
+/*
+ * ARM64 function for seting up MSI irqs.
+ * Based on driver/pci/msi.c: arch_setup_msi_irqs().
+ *
+ * Note:
+ * Current implementation assumes that all interrupt controller used in
+ * ARM64 architecture _MUST_ supports multi-MSI.
+ */
+int arm64_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
+{
+	struct msi_desc *entry;
+	int ret;
+
+	list_for_each_entry(entry, &dev->msi_list, list) {
+		ret = arch_setup_msi_irq(dev, entry);
+		if (ret < 0)
+			return ret;
+		if (ret > 0)
+			return -ENOSPC;
+	}
+
+	return 0;
+}
diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index 2471e4c..7b52e67 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -99,13 +99,26 @@ static void gicv2m_teardown_msi_irq(struct msi_chip *chip, unsigned int irq)
 	spin_unlock(&data->msi_cnt_lock);
 }
 
+static int gicv2m_msi_get_vec_count(struct pci_dev *pdev, struct msi_desc *desc)
+{
+	int ret = -EINVAL;
+#ifdef CONFIG_PCI_MSI
+	if (desc->msi_attrib.is_msix)
+		ret = pci_msix_vec_count(pdev);
+	else
+		ret = pci_msi_vec_count(pdev);
+#endif
+	return ret;
+}
+
 static int gicv2m_setup_msi_irq(struct msi_chip *chip,
 				struct pci_dev *pdev,
 				struct msi_desc *desc)
 {
-	int irq, avail;
+	int i, irq, nvec, avail;
 	struct msi_msg msg;
 	phys_addr_t addr;
+	struct msi_desc *entry;
 	struct v2m_data *data = container_of(chip, struct v2m_data, msi_chip);
 
 	if (!desc) {
@@ -114,16 +127,70 @@ static int gicv2m_setup_msi_irq(struct msi_chip *chip,
 		return -EINVAL;
 	}
 
-	avail = alloc_msi_irq(data, 1, &irq);
-	if (avail != 0) {
-		dev_err(&pdev->dev,
-			"GICv2m: MSI setup failed. Cannnot allocate IRQ\n");
-		return -ENOSPC;
-	}
+	if (desc->msi_attrib.is_msix) {
+		/**
+		 * For MSIx:
+		 * We allocate one irq at a time
+		 */
+		avail = alloc_msi_irq(data, 1, &irq);
+		if (avail != 0) {
+			dev_err(&pdev->dev,
+				"GICv2m: MSI setup failed. Cannnot allocate IRQ\n");
+			return -ENOSPC;
+		}
 
-	irq_set_chip_data(irq, chip);
-	irq_set_msi_desc(irq, desc);
-	irq_set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
+		irq_set_chip_data(irq, chip);
+		irq_set_msi_desc(irq, desc);
+		irq_set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
+	} else {
+		/**
+		 * For MSI and Multi-MSI:
+		 * All requested irqs are allocated and setup at
+		 * once. Subsequent calls to this function would simply return
+		 * success. This is to avoid having to implement a separate
+		 * function for setting up multiple irqs.
+		 */
+		BUG_ON(list_empty(&pdev->msi_list));
+		WARN_ON(!list_is_singular(&pdev->msi_list));
+
+		nvec = gicv2m_msi_get_vec_count(pdev, desc);
+		if (WARN_ON(nvec <= 0))
+			return nvec;
+
+		entry = list_first_entry(&pdev->msi_list,
+					 struct msi_desc, list);
+
+		if ((nvec > 1) && (entry->msi_attrib.multiple))
+			return 0;
+
+		avail = alloc_msi_irq(data, nvec, &irq);
+		if (avail != 0) {
+			dev_err(&pdev->dev,
+				"GICv2m: Failed to allocate %d irqs.\n", nvec);
+			return avail;
+		}
+
+		if (nvec > 1) {
+			/* Set lowest of the new interrupts assigned
+			 * to the PCI device
+			 */
+			entry->nvec_used = nvec;
+			entry->msi_attrib.multiple = ilog2(
+						__roundup_pow_of_two(nvec));
+		}
+
+		for (i = 0; i < nvec; i++) {
+			irq_set_chip_data(irq+i, chip);
+			if (irq_set_msi_desc_off(irq, i, entry)) {
+				dev_err(&pdev->dev,
+					"GICv2m: Failed to set up MSI irq %d\n",
+					(irq+i));
+				return -EINVAL;
+			}
+
+			irq_set_irq_type((irq+i), IRQ_TYPE_EDGE_RISING);
+		}
+	}
 
 	addr = data->res.start + V2M_MSI_SETSPI_NS;
 	msg.address_hi = (u32)(addr >> 32);
-- 
1.9.3