[CELL] add support for MSI on Axon-based Cell systems

This patch adds support for the setup and decoding of MSIs
on Axon-based Cell systems, using the MSIC mechanism.

This involves setting up an area of BE memory which the Axon
then uses as a FIFO for MSI messages. When one or more MSIs
are decoded by the MSIC we receive an interrupt on the MPIC,
and the MSI messages are written into the FIFO. At the moment
we use a 64KB FIFO, one per MSIC/BE.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

arch/powerpc/platforms/cell/Makefile

@@ -25,3 +25,5 @@ obj-$(CONFIG_SPU_BASE)			+= spu_callbacks.o spu_base.o \
 					   $(spu-priv1-y) \
 					   $(spu-manage-y) \
 					   spufs/
+
+obj-$(CONFIG_PCI_MSI)			+= axon_msi.o

arch/powerpc/platforms/cell/axon_msi.c

+/*
+ * Copyright 2007, Michael Ellerman, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/msi.h>
+#include <linux/reboot.h>
+
+#include <asm/dcr.h>
+#include <asm/machdep.h>
+#include <asm/prom.h>
+
+
+/*
+ * MSIC registers, specified as offsets from dcr_base
+ */
+#define MSIC_CTRL_REG	0x0
+
+/* Base Address registers specify FIFO location in BE memory */
+#define MSIC_BASE_ADDR_HI_REG	0x3
+#define MSIC_BASE_ADDR_LO_REG	0x4
+
+/* Hold the read/write offsets into the FIFO */
+#define MSIC_READ_OFFSET_REG	0x5
+#define MSIC_WRITE_OFFSET_REG	0x6
+
+
+/* MSIC control register flags */
+#define MSIC_CTRL_ENABLE		0x0001
+#define MSIC_CTRL_FIFO_FULL_ENABLE	0x0002
+#define MSIC_CTRL_IRQ_ENABLE		0x0008
+#define MSIC_CTRL_FULL_STOP_ENABLE	0x0010
+
+/*
+ * The MSIC can be configured to use a FIFO of 32KB, 64KB, 128KB or 256KB.
+ * Currently we're using a 64KB FIFO size.
+ */
+#define MSIC_FIFO_SIZE_SHIFT	16
+#define MSIC_FIFO_SIZE_BYTES	(1 << MSIC_FIFO_SIZE_SHIFT)
+
+/*
+ * To configure the FIFO size as (1 << n) bytes, we write (n - 15) into bits
+ * 8-9 of the MSIC control reg.
+ */
+#define MSIC_CTRL_FIFO_SIZE	(((MSIC_FIFO_SIZE_SHIFT - 15) << 8) & 0x300)
+
+/*
+ * We need to mask the read/write offsets to make sure they stay within
+ * the bounds of the FIFO. Also they should always be 16-byte aligned.
+ */
+#define MSIC_FIFO_SIZE_MASK	((MSIC_FIFO_SIZE_BYTES - 1) & ~0xFu)
+
+/* Each entry in the FIFO is 16 bytes, the first 4 bytes hold the irq # */
+#define MSIC_FIFO_ENTRY_SIZE	0x10
+
+
+struct axon_msic {
+	struct device_node *dn;
+	struct irq_host *irq_host;
+	__le32 *fifo;
+	dcr_host_t dcr_host;
+	struct list_head list;
+	u32 read_offset;
+	u32 dcr_base;
+};
+
+static LIST_HEAD(axon_msic_list);
+
+static void msic_dcr_write(struct axon_msic *msic, unsigned int dcr_n, u32 val)
+{
+	pr_debug("axon_msi: dcr_write(0x%x, 0x%x)\n", val, dcr_n);
+
+	dcr_write(msic->dcr_host, msic->dcr_base + dcr_n, val);
+}
+
+static u32 msic_dcr_read(struct axon_msic *msic, unsigned int dcr_n)
+{
+	return dcr_read(msic->dcr_host, msic->dcr_base + dcr_n);
+}
+
+static void axon_msi_cascade(unsigned int irq, struct irq_desc *desc)
+{
+	struct axon_msic *msic = get_irq_data(irq);
+	u32 write_offset, msi;
+	int idx;
+
+	write_offset = msic_dcr_read(msic, MSIC_WRITE_OFFSET_REG);
+	pr_debug("axon_msi: original write_offset 0x%x\n", write_offset);
+
+	/* write_offset doesn't wrap properly, so we have to mask it */
+	write_offset &= MSIC_FIFO_SIZE_MASK;
+
+	while (msic->read_offset != write_offset) {
+		idx  = msic->read_offset / sizeof(__le32);
+		msi  = le32_to_cpu(msic->fifo[idx]);
+		msi &= 0xFFFF;
+
+		pr_debug("axon_msi: woff %x roff %x msi %x\n",
+			  write_offset, msic->read_offset, msi);
+
+		msic->read_offset += MSIC_FIFO_ENTRY_SIZE;
+		msic->read_offset &= MSIC_FIFO_SIZE_MASK;
+
+		if (msi < NR_IRQS && irq_map[msi].host == msic->irq_host)
+			generic_handle_irq(msi);
+		else
+			pr_debug("axon_msi: invalid irq 0x%x!\n", msi);
+	}
+
+	desc->chip->eoi(irq);
+}
+
+static struct axon_msic *find_msi_translator(struct pci_dev *dev)
+{
+	struct irq_host *irq_host;
+	struct device_node *dn, *tmp;
+	const phandle *ph;
+	struct axon_msic *msic = NULL;
+
+	dn = pci_device_to_OF_node(dev);
+	if (!dn) {
+		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
+		return NULL;
+	}
+
+	for (; dn; tmp = of_get_parent(dn), of_node_put(dn), dn = tmp) {
+		ph = of_get_property(dn, "msi-translator", NULL);
+		if (ph)
+			break;
+	}
+
+	if (!ph) {
+		dev_dbg(&dev->dev,
+			"axon_msi: no msi-translator property found\n");
+		goto out_error;
+	}
+
+	tmp = dn;
+	dn = of_find_node_by_phandle(*ph);
+	if (!dn) {
+		dev_dbg(&dev->dev,
+			"axon_msi: msi-translator doesn't point to a node\n");
+		goto out_error;
+	}
+
+	irq_host = irq_find_host(dn);
+	if (!irq_host) {
+		dev_dbg(&dev->dev, "axon_msi: no irq_host found for node %s\n",
+			dn->full_name);
+		goto out_error;
+	}
+
+	msic = irq_host->host_data;
+
+out_error:
+	of_node_put(dn);
+	of_node_put(tmp);
+
+	return msic;
+}
+
+static int axon_msi_check_device(struct pci_dev *dev, int nvec, int type)
+{
+	if (!find_msi_translator(dev))
+		return -ENODEV;
+
+	return 0;
+}
+
+static int setup_msi_msg_address(struct pci_dev *dev, struct msi_msg *msg)
+{
+	struct device_node *dn, *tmp;
+	struct msi_desc *entry;
+	int len;
+	const u32 *prop;
+
+	dn = pci_device_to_OF_node(dev);
+	if (!dn) {
+		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
+		return -ENODEV;
+	}
+
+	entry = list_first_entry(&dev->msi_list, struct msi_desc, list);
+
+	for (; dn; tmp = of_get_parent(dn), of_node_put(dn), dn = tmp) {
+		if (entry->msi_attrib.is_64) {
+			prop = of_get_property(dn, "msi-address-64", &len);
+			if (prop)
+				break;
+		}
+
+		prop = of_get_property(dn, "msi-address-32", &len);
+		if (prop)
+			break;
+	}
+
+	if (!prop) {
+		dev_dbg(&dev->dev,
+			"axon_msi: no msi-address-(32|64) properties found\n");
+		return -ENOENT;
+	}
+
+	switch (len) {
+	case 8:
+		msg->address_hi = prop[0];
+		msg->address_lo = prop[1];
+		break;
+	case 4:
+		msg->address_hi = 0;
+		msg->address_lo = prop[0];
+		break;
+	default:
+		dev_dbg(&dev->dev,
+			"axon_msi: malformed msi-address-(32|64) property\n");
+		of_node_put(dn);
+		return -EINVAL;
+	}
+
+	of_node_put(dn);
+
+	return 0;
+}
+
+static int axon_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
+{
+	unsigned int virq, rc;
+	struct msi_desc *entry;
+	struct msi_msg msg;
+	struct axon_msic *msic;
+
+	msic = find_msi_translator(dev);
+	if (!msic)
+		return -ENODEV;
+
+	rc = setup_msi_msg_address(dev, &msg);
+	if (rc)
+		return rc;
+
+	/* We rely on being able to stash a virq in a u16 */
+	BUILD_BUG_ON(NR_IRQS > 65536);
+
+	list_for_each_entry(entry, &dev->msi_list, list) {
+		virq = irq_create_direct_mapping(msic->irq_host);
+		if (virq == NO_IRQ) {
+			dev_warn(&dev->dev,
+				 "axon_msi: virq allocation failed!\n");
+			return -1;
+		}
+		dev_dbg(&dev->dev, "axon_msi: allocated virq 0x%x\n", virq);
+
+		set_irq_msi(virq, entry);
+		msg.data = virq;
+		write_msi_msg(virq, &msg);
+	}
+
+	return 0;
+}
+
+static void axon_msi_teardown_msi_irqs(struct pci_dev *dev)
+{
+	struct msi_desc *entry;
+
+	dev_dbg(&dev->dev, "axon_msi: tearing down msi irqs\n");
+
+	list_for_each_entry(entry, &dev->msi_list, list) {
+		if (entry->irq == NO_IRQ)
+			continue;
+
+		set_irq_msi(entry->irq, NULL);
+		irq_dispose_mapping(entry->irq);
+	}
+}
+
+static struct irq_chip msic_irq_chip = {
+	.mask		= mask_msi_irq,
+	.unmask		= unmask_msi_irq,
+	.shutdown	= unmask_msi_irq,
+	.typename	= "AXON-MSI",
+};
+
+static int msic_host_map(struct irq_host *h, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	set_irq_chip_and_handler(virq, &msic_irq_chip, handle_simple_irq);
+
+	return 0;
+}
+
+static int msic_host_match(struct irq_host *host, struct device_node *dn)
+{
+	struct axon_msic *msic = host->host_data;
+
+	return msic->dn == dn;
+}
+
+static struct irq_host_ops msic_host_ops = {
+	.match	= msic_host_match,
+	.map	= msic_host_map,
+};
+
+static int axon_msi_notify_reboot(struct notifier_block *nb,
+				  unsigned long code, void *data)
+{
+	struct axon_msic *msic;
+	u32 tmp;
+
+	list_for_each_entry(msic, &axon_msic_list, list) {
+		pr_debug("axon_msi: disabling %s\n", msic->dn->full_name);
+		tmp  = msic_dcr_read(msic, MSIC_CTRL_REG);
+		tmp &= ~MSIC_CTRL_ENABLE & ~MSIC_CTRL_IRQ_ENABLE;
+		msic_dcr_write(msic, MSIC_CTRL_REG, tmp);
+	}
+
+	return 0;
+}
+
+static struct notifier_block axon_msi_reboot_notifier = {
+	.notifier_call = axon_msi_notify_reboot
+};
+
+static int axon_msi_setup_one(struct device_node *dn)
+{
+	struct page *page;
+	struct axon_msic *msic;
+	unsigned int virq;
+	int dcr_len;
+
+	pr_debug("axon_msi: setting up dn %s\n", dn->full_name);
+
+	msic = kzalloc(sizeof(struct axon_msic), GFP_KERNEL);
+	if (!msic) {
+		printk(KERN_ERR "axon_msi: couldn't allocate msic for %s\n",
+		       dn->full_name);
+		goto out;
+	}
+
+	msic->dcr_base = dcr_resource_start(dn, 0);
+	dcr_len = dcr_resource_len(dn, 0);
+
+	if (msic->dcr_base == 0 || dcr_len == 0) {
+		printk(KERN_ERR
+		       "axon_msi: couldn't parse dcr properties on %s\n",
+			dn->full_name);
+		goto out;
+	}
+
+	msic->dcr_host = dcr_map(dn, msic->dcr_base, dcr_len);
+	if (!DCR_MAP_OK(msic->dcr_host)) {
+		printk(KERN_ERR "axon_msi: dcr_map failed for %s\n",
+		       dn->full_name);
+		goto out_free_msic;
+	}
+
+	page = alloc_pages_node(of_node_to_nid(dn), GFP_KERNEL,
+				get_order(MSIC_FIFO_SIZE_BYTES));
+	if (!page) {
+		printk(KERN_ERR "axon_msi: couldn't allocate fifo for %s\n",
+		       dn->full_name);
+		goto out_free_msic;
+	}
+
+	msic->fifo = page_address(page);
+
+	msic->irq_host = irq_alloc_host(IRQ_HOST_MAP_NOMAP, NR_IRQS,
+					&msic_host_ops, 0);
+	if (!msic->irq_host) {
+		printk(KERN_ERR "axon_msi: couldn't allocate irq_host for %s\n",
+		       dn->full_name);
+		goto out_free_fifo;
+	}
+
+	msic->irq_host->host_data = msic;
+
+	virq = irq_of_parse_and_map(dn, 0);
+	if (virq == NO_IRQ) {
+		printk(KERN_ERR "axon_msi: irq parse and map failed for %s\n",
+		       dn->full_name);
+		goto out_free_host;
+	}
+
+	msic->dn = of_node_get(dn);
+
+	set_irq_data(virq, msic);
+	set_irq_chained_handler(virq, axon_msi_cascade);
+	pr_debug("axon_msi: irq 0x%x setup for axon_msi\n", virq);
+
+	/* Enable the MSIC hardware */
+	msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, (u64)msic->fifo >> 32);
+	msic_dcr_write(msic, MSIC_BASE_ADDR_LO_REG,
+				  (u64)msic->fifo & 0xFFFFFFFF);
+	msic_dcr_write(msic, MSIC_CTRL_REG,
+			MSIC_CTRL_IRQ_ENABLE | MSIC_CTRL_ENABLE |
+			MSIC_CTRL_FIFO_SIZE);
+
+	list_add(&msic->list, &axon_msic_list);
+
+	printk(KERN_DEBUG "axon_msi: setup MSIC on %s\n", dn->full_name);
+
+	return 0;
+
+out_free_host:
+	kfree(msic->irq_host);
+out_free_fifo:
+	__free_pages(virt_to_page(msic->fifo), get_order(MSIC_FIFO_SIZE_BYTES));
+out_free_msic:
+	kfree(msic);
+out:
+
+	return -1;
+}
+
+static int axon_msi_init(void)
+{
+	struct device_node *dn;
+	int found = 0;
+
+	pr_debug("axon_msi: initialising ...\n");
+
+	for_each_compatible_node(dn, NULL, "ibm,axon-msic") {
+		if (axon_msi_setup_one(dn) == 0)
+			found++;
+	}
+
+	if (found) {
+		ppc_md.setup_msi_irqs = axon_msi_setup_msi_irqs;
+		ppc_md.teardown_msi_irqs = axon_msi_teardown_msi_irqs;
+		ppc_md.msi_check_device = axon_msi_check_device;
+
+		register_reboot_notifier(&axon_msi_reboot_notifier);
+
+		pr_debug("axon_msi: registered callbacks!\n");
+	}
+
+	return 0;
+}
+arch_initcall(axon_msi_init);