[RFC/PATCH 13/16] MPIC MSI allocator

[Michael Ellerman <michael@ellerman.id.au>]

To support MSI on MPIC we need a way to reserve and allocate hardware irq
numbers, this patch implements an allocator for that.

Updated to only do dogy-U3-fallback-hacks on U3, all other platforms must
define a "msi-ranges" property on their MPIC node for MSI to work.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---

 arch/powerpc/sysdev/Makefile   |    5 -
 arch/powerpc/sysdev/mpic.c     |    4 
 arch/powerpc/sysdev/mpic.h     |   27 ++++++
 arch/powerpc/sysdev/mpic_msi.c |  171 +++++++++++++++++++++++++++++++++++++++++
 include/asm-powerpc/mpic.h     |   11 ++
 5 files changed, 217 insertions(+), 1 deletion(-)

Index: msi/arch/powerpc/sysdev/Makefile
===================================================================
--- msi.orig/arch/powerpc/sysdev/Makefile
+++ msi/arch/powerpc/sysdev/Makefile
@@ -2,7 +2,10 @@ ifeq ($(CONFIG_PPC64),y)
 EXTRA_CFLAGS			+= -mno-minimal-toc
 endif
 
-obj-$(CONFIG_MPIC)		+= mpic.o
+mpic-obj-y			:= mpic.o
+mpic-obj-$(CONFIG_PCI_MSI)	+= mpic_msi.o
+obj-$(CONFIG_MPIC)		+= $(mpic-obj-y)
+
 obj-$(CONFIG_PPC_INDIRECT_PCI)	+= indirect_pci.o
 obj-$(CONFIG_PPC_MPC106)	+= grackle.o
 obj-$(CONFIG_PPC_DCR)		+= dcr.o
Index: msi/arch/powerpc/sysdev/mpic.c
===================================================================
--- msi.orig/arch/powerpc/sysdev/mpic.c
+++ msi/arch/powerpc/sysdev/mpic.c
@@ -36,6 +36,8 @@
 #include <asm/mpic.h>
 #include <asm/smp.h>
 
+#include "mpic.h"
+
 #ifdef DEBUG
 #define DBG(fmt...) printk(fmt)
 #else
@@ -825,6 +827,8 @@ static int mpic_host_map(struct irq_host
 	if (hw >= mpic->irq_count)
 		return -EINVAL;
 
+	mpic_msi_reserve_hwirq(mpic, hw);
+
 	/* Default chip */
 	chip = &mpic->hc_irq;
 
Index: msi/arch/powerpc/sysdev/mpic.h
===================================================================
--- /dev/null
+++ msi/arch/powerpc/sysdev/mpic.h
@@ -0,0 +1,27 @@
+#ifndef _POWERPC_SYSDEV_MPIC_H
+#define _POWERPC_SYSDEV_MPIC_H
+
+/*
+ * Copyright 2006-2007, 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; version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/bitmap.h>
+#include <asm/msi.h>
+
+#ifdef CONFIG_PCI_MSI
+extern void mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq);
+#else
+static inline void mpic_msi_reserve_hwirq(struct mpic *mpic,
+					  irq_hw_number_t hwirq)
+{
+	return;
+}
+#endif
+
+#endif /* _POWERPC_SYSDEV_MPIC_H */
Index: msi/arch/powerpc/sysdev/mpic_msi.c
===================================================================
--- /dev/null
+++ msi/arch/powerpc/sysdev/mpic_msi.c
@@ -0,0 +1,171 @@
+/*
+ * Copyright 2006-2007, 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; version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/irq.h>
+#include <linux/bootmem.h>
+#include <linux/msi-ops.h>
+#include <asm/mpic.h>
+#include <asm/prom.h>
+#include <asm/hw_irq.h>
+#include <asm/ppc-pci.h>
+
+
+static void __mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq)
+{
+	msi_debug("reserving hwirq 0x%lx\n", hwirq);
+	bitmap_allocate_region(mpic->hwirq_bitmap, hwirq, 0);
+}
+
+void mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq)
+{
+	unsigned long flags;
+
+	/* The mpic calls this even when there is no allocator setup */
+	if (!mpic->hwirq_bitmap)
+		return;
+
+	spin_lock_irqsave(&mpic->bitmap_lock, flags);
+	__mpic_msi_reserve_hwirq(mpic, hwirq);
+	spin_unlock_irqrestore(&mpic->bitmap_lock, flags);
+}
+
+irq_hw_number_t mpic_msi_alloc_hwirqs(struct mpic *mpic, int num)
+{
+	unsigned long flags;
+	int offset, order = fls(num);
+
+	spin_lock_irqsave(&mpic->bitmap_lock, flags);
+	/*
+	 * This is fast, but stricter than we need. We might want to add
+	 * a fallback routine which does a linear search with no alignment.
+	 */
+	offset = bitmap_find_free_region(mpic->hwirq_bitmap, mpic->irq_count,
+					 order);
+	spin_unlock_irqrestore(&mpic->bitmap_lock, flags);
+
+	msi_debug("allocated %d (2^%d) at offset %d\n", num, order, offset);
+
+	return offset;
+}
+
+void mpic_msi_free_hwirqs(struct mpic *mpic, int offset, int num)
+{
+	unsigned long flags;
+	int order = fls(num);
+
+	msi_debug("freeing %d (2^%d) at offset %d\n", num, order, offset);
+
+	spin_lock_irqsave(&mpic->bitmap_lock, flags);
+	bitmap_release_region(mpic->hwirq_bitmap, offset, order);
+	spin_unlock_irqrestore(&mpic->bitmap_lock, flags);
+}
+
+#ifdef CONFIG_MPIC_BROKEN_U3
+static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic)
+{
+	irq_hw_number_t hwirq;
+	struct irq_host_ops *ops = mpic->irqhost->ops;
+	struct device_node *np;
+	int flags, index, i;
+	struct of_irq oirq;
+
+	msi_debug("found U3, guessing msi allocator setup\n");
+
+	/* Reserve source numbers we know are reserved in the HW */
+	for (i = 0;   i < 8;   i++) __mpic_msi_reserve_hwirq(mpic, i);
+	for (i = 42;  i < 46;  i++) __mpic_msi_reserve_hwirq(mpic, i);
+	for (i = 100; i < 105; i++) __mpic_msi_reserve_hwirq(mpic, i);
+
+	np = NULL;
+	while ((np = of_find_all_nodes(np))) {
+		msi_debug("mapping hwirqs for %s\n", np->full_name);
+
+		index = 0;
+		while (of_irq_map_one(np, index++, &oirq) == 0) {
+			ops->xlate(mpic->irqhost, NULL, oirq.specifier,
+						oirq.size, &hwirq, &flags);
+			__mpic_msi_reserve_hwirq(mpic, hwirq);
+		}
+	}
+
+	return 0;
+}
+#else
+static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic) { return -1; }
+#endif
+
+static int mpic_msi_reserve_dt_hwirqs(struct mpic *mpic)
+{
+	int i, len;
+	const u32 *p;
+
+	p = get_property(mpic->of_node, "msi-available-ranges", &len);
+	if (!p) {
+		msi_debug("no msi-available-ranges property found on %s\n",
+			  mpic->of_node->full_name);
+		return -ENODEV;
+	}
+
+	if (len % 8 != 0) {
+		printk(KERN_WARNING "Malformed msi-available-ranges "
+		       "property on %s\n", mpic->of_node->full_name);
+		return -EINVAL;
+	}
+
+	bitmap_allocate_region(mpic->hwirq_bitmap, 0, fls(mpic->irq_count));
+
+	/* Format is: (<u32 start> <u32 count>)+ */
+	len /= sizeof(u32);
+	for (i = 0; i < len / 2; i++, p += 2)
+		mpic_msi_free_hwirqs(mpic, *p, *(p + 1));
+
+	return 0;
+}
+
+int mpic_msi_init_allocator(struct mpic *mpic)
+{
+	int rc, size;
+
+	BUG_ON(mpic->hwirq_bitmap);
+	spin_lock_init(&mpic->bitmap_lock);
+
+	size = mpic->irq_count / 8;
+	msi_debug("allocator bitmap size is 0x%x bytes\n", size);
+
+	if (mem_init_done)
+		mpic->hwirq_bitmap = kmalloc(size, GFP_KERNEL);
+	else
+		mpic->hwirq_bitmap = alloc_bootmem(size);
+
+	if (!mpic->hwirq_bitmap) {
+		msi_debug("no mem allocating allocator bitmap!\n");
+		return -ENOMEM;
+	}
+
+	memset(mpic->hwirq_bitmap, 0, size);
+
+	rc = mpic_msi_reserve_dt_hwirqs(mpic);
+	if (rc) {
+		if (mpic->flags & MPIC_BROKEN_U3)
+			rc = mpic_msi_reserve_u3_hwirqs(mpic);
+
+		if (rc)
+			goto out_free;
+	}
+
+	return 0;
+
+ out_free:
+	if (mem_init_done)
+		kfree(mpic->hwirq_bitmap);
+
+	mpic->hwirq_bitmap = NULL;
+	return rc;
+}
Index: msi/include/asm-powerpc/mpic.h
===================================================================
--- msi.orig/include/asm-powerpc/mpic.h
+++ msi/include/asm-powerpc/mpic.h
@@ -300,6 +300,11 @@ struct mpic
 	u32			*hw_set;
 #endif
 
+#ifdef CONFIG_PCI_MSI
+	spinlock_t		bitmap_lock;
+	unsigned long		*hwirq_bitmap;
+#endif
+
 	/* link */
 	struct mpic		*next;
 };
@@ -446,5 +451,11 @@ void mpic_set_clk_ratio(struct mpic *mpi
 /* Enable/Disable EPIC serial interrupt mode */
 void mpic_set_serial_int(struct mpic *mpic, int enable);
 
+#ifdef CONFIG_PCI_MSI
+extern int mpic_msi_init_allocator(struct mpic *mpic);
+extern irq_hw_number_t mpic_msi_alloc_hwirqs(struct mpic *mpic, int num);
+extern void mpic_msi_free_hwirqs(struct mpic *mpic, int offset, int num);
+#endif
+
 #endif /* __KERNEL__ */
 #endif	/* _ASM_POWERPC_MPIC_H */