irqchip: Add Layerscape SCFG MSI controller support

Some kind of Freescale Layerscape SoC provides a MSI
implementation which uses two SCFG registers MSIIR and
MSIR to support 32 MSI interrupts for each PCIe controller.
The patch is to support it.

Signed-off-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/Kconfig

@@ -246,5 +246,10 @@ config MVEBU_ODMI
 	bool
 	select GENERIC_MSI_IRQ_DOMAIN
 
+config LS_SCFG_MSI
+	def_bool y if SOC_LS1021A || ARCH_LAYERSCAPE
+	depends on PCI && PCI_MSI
+	select PCI_MSI_IRQ_DOMAIN
+
 config PARTITION_PERCPU
 	bool

drivers/irqchip/Makefile

@@ -66,3 +66,4 @@ obj-$(CONFIG_INGENIC_IRQ)		+= irq-ingenic.o
 obj-$(CONFIG_IMX_GPCV2)			+= irq-imx-gpcv2.o
 obj-$(CONFIG_PIC32_EVIC)		+= irq-pic32-evic.o
 obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o
+obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o

drivers/irqchip/irq-ls-scfg-msi.c

@@ -0,0 +1,240 @@
+/*
+ * Freescale SCFG MSI(-X) support
+ *
+ * Copyright (C) 2016 Freescale Semiconductor.
+ *
+ * Author: Minghuan Lian <Minghuan.Lian@nxp.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/kernel.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of_pci.h>
+#include <linux/of_platform.h>
+#include <linux/spinlock.h>
+
+#define MSI_MAX_IRQS	32
+#define MSI_IBS_SHIFT	3
+#define MSIR		4
+
+struct ls_scfg_msi {
+	spinlock_t		lock;
+	struct platform_device	*pdev;
+	struct irq_domain	*parent;
+	struct irq_domain	*msi_domain;
+	void __iomem		*regs;
+	phys_addr_t		msiir_addr;
+	int			irq;
+	DECLARE_BITMAP(used, MSI_MAX_IRQS);
+};
+
+static struct irq_chip ls_scfg_msi_irq_chip = {
+	.name = "MSI",
+	.irq_mask	= pci_msi_mask_irq,
+	.irq_unmask	= pci_msi_unmask_irq,
+};
+
+static struct msi_domain_info ls_scfg_msi_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS |
+		   MSI_FLAG_USE_DEF_CHIP_OPS |
+		   MSI_FLAG_PCI_MSIX),
+	.chip	= &ls_scfg_msi_irq_chip,
+};
+
+static void ls_scfg_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
+{
+	struct ls_scfg_msi *msi_data = irq_data_get_irq_chip_data(data);
+
+	msg->address_hi = upper_32_bits(msi_data->msiir_addr);
+	msg->address_lo = lower_32_bits(msi_data->msiir_addr);
+	msg->data = data->hwirq << MSI_IBS_SHIFT;
+}
+
+static int ls_scfg_msi_set_affinity(struct irq_data *irq_data,
+				    const struct cpumask *mask, bool force)
+{
+	return -EINVAL;
+}
+
+static struct irq_chip ls_scfg_msi_parent_chip = {
+	.name			= "SCFG",
+	.irq_compose_msi_msg	= ls_scfg_msi_compose_msg,
+	.irq_set_affinity	= ls_scfg_msi_set_affinity,
+};
+
+static int ls_scfg_msi_domain_irq_alloc(struct irq_domain *domain,
+					unsigned int virq,
+					unsigned int nr_irqs,
+					void *args)
+{
+	struct ls_scfg_msi *msi_data = domain->host_data;
+	int pos, err = 0;
+
+	WARN_ON(nr_irqs != 1);
+
+	spin_lock(&msi_data->lock);
+	pos = find_first_zero_bit(msi_data->used, MSI_MAX_IRQS);
+	if (pos < MSI_MAX_IRQS)
+		__set_bit(pos, msi_data->used);
+	else
+		err = -ENOSPC;
+	spin_unlock(&msi_data->lock);
+
+	if (err)
+		return err;
+
+	irq_domain_set_info(domain, virq, pos,
+			    &ls_scfg_msi_parent_chip, msi_data,
+			    handle_simple_irq, NULL, NULL);
+
+	return 0;
+}
+
+static void ls_scfg_msi_domain_irq_free(struct irq_domain *domain,
+				   unsigned int virq, unsigned int nr_irqs)
+{
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+	struct ls_scfg_msi *msi_data = irq_data_get_irq_chip_data(d);
+	int pos;
+
+	pos = d->hwirq;
+	if (pos < 0 || pos >= MSI_MAX_IRQS) {
+		pr_err("failed to teardown msi. Invalid hwirq %d\n", pos);
+		return;
+	}
+
+	spin_lock(&msi_data->lock);
+	__clear_bit(pos, msi_data->used);
+	spin_unlock(&msi_data->lock);
+}
+
+static const struct irq_domain_ops ls_scfg_msi_domain_ops = {
+	.alloc	= ls_scfg_msi_domain_irq_alloc,
+	.free	= ls_scfg_msi_domain_irq_free,
+};
+
+static void ls_scfg_msi_irq_handler(struct irq_desc *desc)
+{
+	struct ls_scfg_msi *msi_data = irq_desc_get_handler_data(desc);
+	unsigned long val;
+	int pos, virq;
+
+	chained_irq_enter(irq_desc_get_chip(desc), desc);
+
+	val = ioread32be(msi_data->regs + MSIR);
+	for_each_set_bit(pos, &val, MSI_MAX_IRQS) {
+		virq = irq_find_mapping(msi_data->parent, (31 - pos));
+		if (virq)
+			generic_handle_irq(virq);
+	}
+
+	chained_irq_exit(irq_desc_get_chip(desc), desc);
+}
+
+static int ls_scfg_msi_domains_init(struct ls_scfg_msi *msi_data)
+{
+	/* Initialize MSI domain parent */
+	msi_data->parent = irq_domain_add_linear(NULL,
+						 MSI_MAX_IRQS,
+						 &ls_scfg_msi_domain_ops,
+						 msi_data);
+	if (!msi_data->parent) {
+		dev_err(&msi_data->pdev->dev, "failed to create IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	msi_data->msi_domain = pci_msi_create_irq_domain(
+				of_node_to_fwnode(msi_data->pdev->dev.of_node),
+				&ls_scfg_msi_domain_info,
+				msi_data->parent);
+	if (!msi_data->msi_domain) {
+		dev_err(&msi_data->pdev->dev, "failed to create MSI domain\n");
+		irq_domain_remove(msi_data->parent);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int ls_scfg_msi_probe(struct platform_device *pdev)
+{
+	struct ls_scfg_msi *msi_data;
+	struct resource *res;
+	int ret;
+
+	msi_data = devm_kzalloc(&pdev->dev, sizeof(*msi_data), GFP_KERNEL);
+	if (!msi_data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	msi_data->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(msi_data->regs)) {
+		dev_err(&pdev->dev, "failed to initialize 'regs'\n");
+		return PTR_ERR(msi_data->regs);
+	}
+	msi_data->msiir_addr = res->start;
+
+	msi_data->irq = platform_get_irq(pdev, 0);
+	if (msi_data->irq <= 0) {
+		dev_err(&pdev->dev, "failed to get MSI irq\n");
+		return -ENODEV;
+	}
+
+	msi_data->pdev = pdev;
+	spin_lock_init(&msi_data->lock);
+
+	ret = ls_scfg_msi_domains_init(msi_data);
+	if (ret)
+		return ret;
+
+	irq_set_chained_handler_and_data(msi_data->irq,
+					 ls_scfg_msi_irq_handler,
+					 msi_data);
+
+	platform_set_drvdata(pdev, msi_data);
+
+	return 0;
+}
+
+static int ls_scfg_msi_remove(struct platform_device *pdev)
+{
+	struct ls_scfg_msi *msi_data = platform_get_drvdata(pdev);
+
+	irq_set_chained_handler_and_data(msi_data->irq, NULL, NULL);
+
+	irq_domain_remove(msi_data->msi_domain);
+	irq_domain_remove(msi_data->parent);
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id ls_scfg_msi_id[] = {
+	{ .compatible = "fsl,1s1021a-msi", },
+	{ .compatible = "fsl,1s1043a-msi", },
+	{},
+};
+
+static struct platform_driver ls_scfg_msi_driver = {
+	.driver = {
+		.name = "ls-scfg-msi",
+		.of_match_table = ls_scfg_msi_id,
+	},
+	.probe = ls_scfg_msi_probe,
+	.remove = ls_scfg_msi_remove,
+};
+
+module_platform_driver(ls_scfg_msi_driver);
+
+MODULE_AUTHOR("Minghuan Lian <Minghuan.Lian@nxp.com>");
+MODULE_DESCRIPTION("Freescale Layerscape SCFG MSI controller driver");
+MODULE_LICENSE("GPL v2");