[PATCH v3 5/6] irqchip: Add Loongson PCH MSI controller

[Jiaxun Yang <jiaxun.yang@flygoat.com>]

This controller appears on Loongson LS7A family of PCH to transform
interrupts from PCI MSI into HyperTransport vectorized interrrupts
and send them to procrssor's HT vector controller.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
--
v2:
	- Style clean-ups
	- Add ack callback
	- Use bitmap_find_free_region
v3:
	- Style clean-ups
	- mutex lock instead of spin lock
	- correct bitmap usage
---
 drivers/irqchip/Kconfig                |  10 +
 drivers/irqchip/Makefile               |   1 +
 drivers/irqchip/irq-loongson-pch-msi.c | 255 +++++++++++++++++++++++++
 3 files changed, 266 insertions(+)
 create mode 100644 drivers/irqchip/irq-loongson-pch-msi.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 5524a621638c..0b6b826dd843 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -549,4 +549,14 @@ config LOONGSON_PCH_PIC
 	help
 	  Support for the Loongson PCH PIC Controller.
 
+config LOONGSON_PCH_MSI
+	bool "Loongson PCH PIC Controller"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	depends on PCI
+	default MACH_LOONGSON64
+	select IRQ_DOMAIN_HIERARCHY
+	select PCI_MSI
+	help
+	  Support for the Loongson PCH MSI Controller.
+
 endmenu
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index acc72331cec8..3a4ce283189a 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -109,3 +109,4 @@ obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
 obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
 obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
 obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o
+obj-$(CONFIG_LOONGSON_PCH_MSI)		+= irq-loongson-pch-msi.o
diff --git a/drivers/irqchip/irq-loongson-pch-msi.c b/drivers/irqchip/irq-loongson-pch-msi.c
new file mode 100644
index 000000000000..73e6124a95ac
--- /dev/null
+++ b/drivers/irqchip/irq-loongson-pch-msi.c
@@ -0,0 +1,255 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@flygoat.com>
+ *  Loongson PCH MSI support
+ */
+
+#define pr_fmt(fmt) "pch-msi: " fmt
+
+#include <linux/irqchip.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>
+
+struct pch_msi_data {
+	struct mutex		msi_map_lock;
+	phys_addr_t		doorbell;
+	u32			irq_first;	/* The vector number that MSIs starts */
+	u32			num_irqs;	/* The number of vectors for MSIs */
+	unsigned long		*msi_map;
+};
+
+static void pch_msi_mask_msi_irq(struct irq_data *d)
+{
+	pci_msi_mask_irq(d);
+	irq_chip_mask_parent(d);
+}
+
+static void pch_msi_unmask_msi_irq(struct irq_data *d)
+{
+	pci_msi_unmask_irq(d);
+	irq_chip_unmask_parent(d);
+}
+
+static struct irq_chip pch_msi_irq_chip = {
+	.name			= "PCH PCI MSI",
+	.irq_mask		= pch_msi_mask_msi_irq,
+	.irq_unmask		= pch_msi_unmask_msi_irq,
+	.irq_ack		= irq_chip_ack_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+};
+
+static int pch_msi_allocate_hwirq(struct pch_msi_data *priv, int num_req)
+{
+	int first;
+
+	mutex_lock(&priv->msi_map_lock);
+
+	first = bitmap_find_free_region(priv->msi_map, priv->num_irqs,
+					get_count_order(num_req));
+	if (first < 0) {
+		mutex_unlock(&priv->msi_map_lock);
+		return -ENOSPC;
+	}
+
+	mutex_unlock(&priv->msi_map_lock);
+
+	return priv->irq_first + first;
+}
+
+static void pch_msi_free_hwirq(struct pch_msi_data *priv,
+				int hwirq, int num_req)
+{
+	int first = hwirq - priv->irq_first;
+
+	mutex_lock(&priv->msi_map_lock);
+	bitmap_release_region(priv->msi_map, first, get_count_order(num_req));
+	mutex_unlock(&priv->msi_map_lock);
+}
+
+static void pch_msi_compose_msi_msg(struct irq_data *data,
+					struct msi_msg *msg)
+{
+	struct pch_msi_data *priv = irq_data_get_irq_chip_data(data);
+
+	msg->address_hi = upper_32_bits(priv->doorbell);
+	msg->address_lo = lower_32_bits(priv->doorbell);
+	msg->data = data->hwirq;
+}
+
+static struct msi_domain_info pch_msi_domain_info = {
+	.flags		= MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+			  MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
+	.chip	= &pch_msi_irq_chip,
+};
+
+static struct irq_chip middle_irq_chip = {
+	.name			= "PCH MSI",
+	.irq_mask		= irq_chip_mask_parent,
+	.irq_unmask		= irq_chip_unmask_parent,
+	.irq_ack		= irq_chip_ack_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+	.irq_compose_msi_msg	= pch_msi_compose_msi_msg,
+};
+
+static int pch_msi_parent_domain_alloc(struct irq_domain *domain,
+					unsigned int virq, int hwirq)
+{
+	struct irq_fwspec fwspec;
+	int ret;
+
+	fwspec.fwnode = domain->parent->fwnode;
+	fwspec.param_count = 1;
+	fwspec.param[0] = hwirq;
+
+	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int pch_msi_middle_domain_alloc(struct irq_domain *domain,
+					   unsigned int virq,
+					   unsigned int nr_irqs, void *args)
+{
+	struct pch_msi_data *priv = domain->host_data;
+	int hwirq, err, i;
+
+	hwirq = pch_msi_allocate_hwirq(priv, nr_irqs);
+	if (hwirq < 0)
+		return hwirq;
+
+	for (i = 0; i < nr_irqs; i++) {
+		err = pch_msi_parent_domain_alloc(domain, virq + i, hwirq + i);
+		if (err)
+			goto err_hwirq;
+
+		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
+					      &middle_irq_chip, priv);
+	}
+
+	return 0;
+
+err_hwirq:
+	pch_msi_free_hwirq(priv, hwirq, nr_irqs);
+	irq_domain_free_irqs_parent(domain, virq, i - 1);
+
+	return err;
+}
+
+static void pch_msi_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 pch_msi_data *priv = irq_data_get_irq_chip_data(d);
+
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+	pch_msi_free_hwirq(priv, d->hwirq, nr_irqs);
+}
+
+static const struct irq_domain_ops pch_msi_middle_domain_ops = {
+	.alloc	= pch_msi_middle_domain_alloc,
+	.free	= pch_msi_middle_domain_free,
+};
+
+static int pch_msi_init_domains(struct pch_msi_data *priv,
+				struct device_node *node,
+				struct irq_domain *parent)
+{
+	struct irq_domain *middle_domain, *msi_domain;
+
+	middle_domain = irq_domain_create_linear(of_node_to_fwnode(node),
+						priv->num_irqs,
+						&pch_msi_middle_domain_ops,
+						priv);
+	if (!middle_domain) {
+		pr_err("Failed to create the MSI middle domain\n");
+		return -ENOMEM;
+	}
+
+	middle_domain->parent = parent;
+	irq_domain_update_bus_token(middle_domain, DOMAIN_BUS_NEXUS);
+
+	msi_domain = pci_msi_create_irq_domain(of_node_to_fwnode(node),
+					       &pch_msi_domain_info,
+					       middle_domain);
+	if (!msi_domain) {
+		pr_err("Failed to create PCI MSI domain\n");
+		irq_domain_remove(middle_domain);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int pch_msi_init(struct device_node *node,
+			    struct device_node *parent)
+{
+	struct pch_msi_data *priv;
+	struct irq_domain *parent_domain;
+	struct resource res;
+	int ret;
+
+	parent_domain = irq_find_host(parent);
+	if (!parent_domain) {
+		pr_err("Failed to find the parent domain\n");
+		return -ENXIO;
+	}
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	mutex_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;
+	}
+
+	priv->doorbell = res.start;
+
+	if (of_property_read_u32(node, "loongson,msi-base-vec",
+				&priv->irq_first)) {
+		pr_err("Unable to parse MSI vec base\n");
+		ret = -EINVAL;
+		goto err_priv;
+	}
+
+	if (of_property_read_u32(node, "loongson,msi-num-vecs",
+				&priv->num_irqs)) {
+		pr_err("Unable to parse MSI vec number\n");
+		ret = -EINVAL;
+		goto err_priv;
+	}
+
+	priv->msi_map = bitmap_alloc(priv->num_irqs, GFP_KERNEL);
+	if (!priv->msi_map) {
+		ret = -ENOMEM;
+		goto err_priv;
+	}
+
+	pr_debug("Registering %d MSIs, starting at %d\n",
+		 priv->num_irqs, priv->irq_first);
+
+	ret = pch_msi_init_domains(priv, node, parent_domain);
+	if (ret)
+		goto err_map;
+
+	return 0;
+
+err_map:
+	kfree(priv->msi_map);
+err_priv:
+	kfree(priv);
+	return ret;
+}
+
+IRQCHIP_DECLARE(pch_msi, "loongson,pch-msi-1.0", pch_msi_init);
-- 
2.26.0.rc2