[POWERPC] MPIC MSI allocator

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

New firmware platforms must define a "msi-available-ranges" property on their
MPIC node for MSI to work. For U3/U4 we do a best-guess setup.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

4 files changed, 217 insertions, 1 deletions

diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
index e96ca9618dbb..a1702053297b 100644
--- a/arch/powerpc/sysdev/Makefile
+++ b/arch/powerpc/sysdev/Makefile
@@ -2,7 +2,9 @@ ifeq ($(CONFIG_PPC64),y)
 EXTRA_CFLAGS                    += -mno-minimal-toc
 endif
 
-obj-$(CONFIG_MPIC)              += mpic.o
+mpic-msi-obj-$(CONFIG_PCI_MSI)  += mpic_msi.o
+obj-$(CONFIG_MPIC)              += mpic.o $(mpic-msi-obj-y)
+
 obj-$(CONFIG_PPC_INDIRECT_PCI)  += indirect_pci.o
 obj-$(CONFIG_PPC_MPC106)        += grackle.o
 obj-$(CONFIG_PPC_DCR)           += dcr.o
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 33ecf89702d4..fc0428aea0c0 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/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
@@ -891,6 +893,8 @@ static int mpic_host_map(struct irq_host *h, unsigned int virq,
         if (hw >= mpic->irq_count)
                 return -EINVAL;
 
+        mpic_msi_reserve_hwirq(mpic, hw);
+
         /* Default chip */
         chip = &mpic->hc_irq;
 
diff --git a/arch/powerpc/sysdev/mpic.h b/arch/powerpc/sysdev/mpic.h
new file mode 100644
index 000000000000..87cb2aea2fb4
--- /dev/null
+++ b/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.
+ *
+ */
+
+#ifdef CONFIG_PCI_MSI
+extern void mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq);
+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);
+#else
+static inline void mpic_msi_reserve_hwirq(struct mpic *mpic,
+                                          irq_hw_number_t hwirq)
+{
+        return;
+}
+#endif
+
+#endif /* _POWERPC_SYSDEV_MPIC_H */
diff --git a/arch/powerpc/sysdev/mpic_msi.c b/arch/powerpc/sysdev/mpic_msi.c
new file mode 100644
index 000000000000..b076793033c2
--- /dev/null
+++ b/arch/powerpc/sysdev/mpic_msi.c
@@ -0,0 +1,183 @@
+/*
+ * 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/bitmap.h>
+#include <linux/msi.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)
+{
+        pr_debug("mpic: 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 = get_count_order(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);
+
+        pr_debug("mpic: allocated 0x%x (2^%d) at offset 0x%x\n",
+                 num, order, offset);
+
+        return offset;
+}
+
+void mpic_msi_free_hwirqs(struct mpic *mpic, int offset, int num)
+{
+        unsigned long flags;
+        int order = get_count_order(num);
+
+        pr_debug("mpic: freeing 0x%x (2^%d) at offset 0x%x\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_U3_HT_IRQS
+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;
+
+        pr_debug("mpic: 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))) {
+                pr_debug("mpic: 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 = of_get_property(mpic->of_node, "msi-available-ranges", &len);
+        if (!p) {
+                pr_debug("mpic: no msi-available-ranges property found on %s\n",
+                          mpic->of_node->full_name);
+                return -ENODEV;
+        }
+
+        if (len % 8 != 0) {
+                printk(KERN_WARNING "mpic: Malformed msi-available-ranges "
+                       "property on %s\n", mpic->of_node->full_name);
+                return -EINVAL;
+        }
+
+        bitmap_allocate_region(mpic->hwirq_bitmap, 0,
+                               get_count_order(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 = BITS_TO_LONGS(mpic->irq_count) * sizeof(long);
+        pr_debug("mpic: 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) {
+                pr_debug("mpic: ENOMEM 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_U3_HT_IRQS)
+                        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;
+}