irqchip: Add the Alpine MSIX interrupt controller

This patch adds the Alpine MSIX interrupt controller driver.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Tsahee Zidenberg <tsahee@annapurnalabs.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

3 files changed, 300 insertions, 0 deletions

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 00bbec6eca0b..7e8c441ff2de 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -65,6 +65,12 @@ config ARMADA_370_XP_IRQ
 	select GENERIC_IRQ_CHIP
 	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
 
+config ALPINE_MSI
+	bool
+	depends on PCI && PCI_MSI
+	select GENERIC_IRQ_CHIP
+	select PCI_MSI_IRQ_DOMAIN
+
 config ATMEL_AIC_IRQ
 	bool
 	select GENERIC_IRQ_CHIP
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 8698710fda37..b03cfcbbac6b 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -1,5 +1,6 @@
 obj-$(CONFIG_IRQCHIP)			+= irqchip.o
 
+obj-$(CONFIG_ALPINE_MSI)		+= irq-alpine-msi.o
 obj-$(CONFIG_ATH79)			+= irq-ath79-cpu.o
 obj-$(CONFIG_ATH79)			+= irq-ath79-misc.o
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
diff --git a/drivers/irqchip/irq-alpine-msi.c b/drivers/irqchip/irq-alpine-msi.c
new file mode 100644
index 000000000000..f8712722a606
--- /dev/null
+++ b/drivers/irqchip/irq-alpine-msi.c
@@ -0,0 +1,293 @@
+/*
+ * Annapurna Labs MSIX support services
+ *
+ * Copyright (C) 2016, Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Antoine Tenart <antoine.tenart@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/irqchip.h>
+#include <linux/irqchip/arm-gic.h>
+#include <linux/msi.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_pci.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+
+#include <asm/irq.h>
+#include <asm-generic/msi.h>
+
+/* MSIX message address format: local GIC target */
+#define ALPINE_MSIX_SPI_TARGET_CLUSTER0		BIT(16)
+
+struct alpine_msix_data {
+	spinlock_t msi_map_lock;
+	phys_addr_t addr;
+	u32 spi_first;		/* The SGI number that MSIs start */
+	u32 num_spis;		/* The number of SGIs for MSIs */
+	unsigned long *msi_map;
+};
+
+static void alpine_msix_mask_msi_irq(struct irq_data *d)
+{
+	pci_msi_mask_irq(d);
+	irq_chip_mask_parent(d);
+}
+
+static void alpine_msix_unmask_msi_irq(struct irq_data *d)
+{
+	pci_msi_unmask_irq(d);
+	irq_chip_unmask_parent(d);
+}
+
+static struct irq_chip alpine_msix_irq_chip = {
+	.name			= "MSIx",
+	.irq_mask		= alpine_msix_mask_msi_irq,
+	.irq_unmask		= alpine_msix_unmask_msi_irq,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+};
+
+static int alpine_msix_allocate_sgi(struct alpine_msix_data *priv, int num_req)
+{
+	int first;
+
+	spin_lock(&priv->msi_map_lock);
+
+	first = bitmap_find_next_zero_area(priv->msi_map, priv->num_spis, 0,
+					   num_req, 0);
+	if (first >= priv->num_spis) {
+		spin_unlock(&priv->msi_map_lock);
+		return -ENOSPC;
+	}
+
+	bitmap_set(priv->msi_map, first, num_req);
+
+	spin_unlock(&priv->msi_map_lock);
+
+	return priv->spi_first + first;
+}
+
+static void alpine_msix_free_sgi(struct alpine_msix_data *priv, unsigned sgi,
+				 int num_req)
+{
+	int first = sgi - priv->spi_first;
+
+	spin_lock(&priv->msi_map_lock);
+
+	bitmap_clear(priv->msi_map, first, num_req);
+
+	spin_unlock(&priv->msi_map_lock);
+}
+
+static void alpine_msix_compose_msi_msg(struct irq_data *data,
+					struct msi_msg *msg)
+{
+	struct alpine_msix_data *priv = irq_data_get_irq_chip_data(data);
+	phys_addr_t msg_addr = priv->addr;
+
+	msg_addr |= (data->hwirq << 3);
+
+	msg->address_hi = upper_32_bits(msg_addr);
+	msg->address_lo = lower_32_bits(msg_addr);
+	msg->data = 0;
+}
+
+static struct msi_domain_info alpine_msix_domain_info = {
+	.flags	= MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		  MSI_FLAG_PCI_MSIX,
+	.chip	= &alpine_msix_irq_chip,
+};
+
+static struct irq_chip middle_irq_chip = {
+	.name			= "alpine_msix_middle",
+	.irq_mask		= irq_chip_mask_parent,
+	.irq_unmask		= irq_chip_unmask_parent,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+	.irq_compose_msi_msg	= alpine_msix_compose_msi_msg,
+};
+
+static int alpine_msix_gic_domain_alloc(struct irq_domain *domain,
+					unsigned int virq, int sgi)
+{
+	struct irq_fwspec fwspec;
+	struct irq_data *d;
+	int ret;
+
+	if (!is_of_node(domain->parent->fwnode))
+		return -EINVAL;
+
+	fwspec.fwnode = domain->parent->fwnode;
+	fwspec.param_count = 3;
+	fwspec.param[0] = 0;
+	fwspec.param[1] = sgi;
+	fwspec.param[2] = IRQ_TYPE_EDGE_RISING;
+
+	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
+	if (ret)
+		return ret;
+
+	d = irq_domain_get_irq_data(domain->parent, virq);
+	d->chip->irq_set_type(d, IRQ_TYPE_EDGE_RISING);
+
+	return 0;
+}
+
+static int alpine_msix_middle_domain_alloc(struct irq_domain *domain,
+					   unsigned int virq,
+					   unsigned int nr_irqs, void *args)
+{
+	struct alpine_msix_data *priv = domain->host_data;
+	int sgi, err, i;
+
+	sgi = alpine_msix_allocate_sgi(priv, nr_irqs);
+	if (sgi < 0)
+		return sgi;
+
+	for (i = 0; i < nr_irqs; i++) {
+		err = alpine_msix_gic_domain_alloc(domain, virq + i, sgi + i);
+		if (err)
+			goto err_sgi;
+
+		irq_domain_set_hwirq_and_chip(domain, virq + i, sgi + i,
+					      &middle_irq_chip, priv);
+	}
+
+	return 0;
+
+err_sgi:
+	while (--i >= 0)
+		irq_domain_free_irqs_parent(domain, virq, i);
+	alpine_msix_free_sgi(priv, sgi, nr_irqs);
+	return err;
+}
+
+static void alpine_msix_middle_domain_free(struct irq_domain *domain,
+					   unsigned int virq,
+					   unsigned int nr_irqs)
+{
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+	struct alpine_msix_data *priv = irq_data_get_irq_chip_data(d);
+
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+	alpine_msix_free_sgi(priv, d->hwirq, nr_irqs);
+}
+
+static const struct irq_domain_ops alpine_msix_middle_domain_ops = {
+	.alloc	= alpine_msix_middle_domain_alloc,
+	.free	= alpine_msix_middle_domain_free,
+};
+
+static int alpine_msix_init_domains(struct alpine_msix_data *priv,
+				    struct device_node *node)
+{
+	struct irq_domain *middle_domain, *msi_domain, *gic_domain;
+	struct device_node *gic_node;
+
+	gic_node = of_irq_find_parent(node);
+	if (!gic_node) {
+		pr_err("Failed to find the GIC node\n");
+		return -ENODEV;
+	}
+
+	gic_domain = irq_find_host(gic_node);
+	if (!gic_domain) {
+		pr_err("Failed to find the GIC domain\n");
+		return -ENXIO;
+	}
+
+	middle_domain = irq_domain_add_tree(NULL,
+					    &alpine_msix_middle_domain_ops,
+					    priv);
+	if (!middle_domain) {
+		pr_err("Failed to create the MSIX middle domain\n");
+		return -ENOMEM;
+	}
+
+	middle_domain->parent = gic_domain;
+
+	msi_domain = pci_msi_create_irq_domain(of_node_to_fwnode(node),
+					       &alpine_msix_domain_info,
+					       middle_domain);
+	if (!msi_domain) {
+		pr_err("Failed to create MSI domain\n");
+		irq_domain_remove(msi_domain);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int alpine_msix_init(struct device_node *node,
+			    struct device_node *parent)
+{
+	struct alpine_msix_data *priv;
+	struct resource res;
+	int ret;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	spin_lock_init(&priv->msi_map_lock);
+
+	ret = of_address_to_resource(node, 0, &res);
+	if (ret) {
+		pr_err("Failed to allocate resource\n");
+		goto err_priv;
+	}
+
+	/*
+	 * The 20 least significant bits of addr provide direct information
+	 * regarding the interrupt destination.
+	 *
+	 * To select the primary GIC as the target GIC, bits [18:17] must be set
+	 * to 0x0. In this case, bit 16 (SPI_TARGET_CLUSTER0) must be set.
+	 */
+	priv->addr = res.start & GENMASK_ULL(63,20);
+	priv->addr |= ALPINE_MSIX_SPI_TARGET_CLUSTER0;
+
+	if (of_property_read_u32(node, "al,msi-base-spi", &priv->spi_first)) {
+		pr_err("Unable to parse MSI base\n");
+		ret = -EINVAL;
+		goto err_priv;
+	}
+
+	if (of_property_read_u32(node, "al,msi-num-spis", &priv->num_spis)) {
+		pr_err("Unable to parse MSI numbers\n");
+		ret = -EINVAL;
+		goto err_priv;
+	}
+
+	priv->msi_map = kzalloc(sizeof(*priv->msi_map) * BITS_TO_LONGS(priv->num_spis),
+				GFP_KERNEL);
+	if (!priv->msi_map) {
+		ret = -ENOMEM;
+		goto err_priv;
+	}
+
+	pr_debug("Registering %d msixs, starting at %d\n",
+		 priv->num_spis, priv->spi_first);
+
+	ret = alpine_msix_init_domains(priv, node);
+	if (ret)
+		goto err_map;
+
+	return 0;
+
+err_map:
+	kfree(priv->msi_map);
+err_priv:
+	kfree(priv);
+	return ret;
+}
+IRQCHIP_DECLARE(alpine_msix, "al,alpine-msix", alpine_msix_init);