[POWERPC] pasemi: Implement MSI support

Implement MSI support for PA Semi PWRficient platforms. MSI is done
through a special range of sources on the openpic controller, and they're
unfortunately breaking the usual concepts of how sources are programmed:

* The source is calculated as 512 + the value written into the MSI
  register
* The vector for this source is added to the source and reported
  through IACK

This means that for simplicity, it makes much more sense to just set the
vector to 0 for the source, since that's really the vector we expect to
see from IACK.

Also, the affinity/priority registers will affect 16 sources at a
time. To avoid most (simple) users from being limited by this, allocate
16 sources per device but use only one. This means that there's a total
of 32 sources.

If we get usage scenarions that need more sources, the allocator should
probably be revised to take an alignment argument and size, not just do
natural alignment.

Finally, since I'm already touching the MPIC names on pasemi, rename
the base one from the somewhat odd " PAS-OPIC  " to "PASEMI-OPIC".

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 172 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/mpic_pasemi_msi.c b/arch/powerpc/sysdev/mpic_pasemi_msi.c
new file mode 100644
index 00000000000..d6bfda30ac8
--- /dev/null
+++ b/arch/powerpc/sysdev/mpic_pasemi_msi.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright 2007, Olof Johansson, PA Semi
+ *
+ * Based on arch/powerpc/sysdev/mpic_u3msi.c:
+ *
+ * Copyright 2006, Segher Boessenkool, IBM Corporation.
+ * 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.
+ *
+ */
+
+#undef DEBUG
+
+#include <linux/irq.h>
+#include <linux/bootmem.h>
+#include <linux/msi.h>
+#include <asm/mpic.h>
+#include <asm/prom.h>
+#include <asm/hw_irq.h>
+#include <asm/ppc-pci.h>
+
+#include "mpic.h"
+
+/* Allocate 16 interrupts per device, to give an alignment of 16,
+ * since that's the size of the grouping w.r.t. affinity. If someone
+ * needs more than 32 MSI's down the road we'll have to rethink this,
+ * but it should be OK for now.
+ */
+#define ALLOC_CHUNK 16
+
+#define PASEMI_MSI_ADDR 0xfc080000
+
+/* A bit ugly, can we get this from the pci_dev somehow? */
+static struct mpic *msi_mpic;
+
+
+static void mpic_pasemi_msi_mask_irq(unsigned int irq)
+{
+	pr_debug("mpic_pasemi_msi_mask_irq %d\n", irq);
+	mask_msi_irq(irq);
+	mpic_mask_irq(irq);
+}
+
+static void mpic_pasemi_msi_unmask_irq(unsigned int irq)
+{
+	pr_debug("mpic_pasemi_msi_unmask_irq %d\n", irq);
+	mpic_unmask_irq(irq);
+	unmask_msi_irq(irq);
+}
+
+static struct irq_chip mpic_pasemi_msi_chip = {
+	.shutdown	= mpic_pasemi_msi_mask_irq,
+	.mask		= mpic_pasemi_msi_mask_irq,
+	.unmask		= mpic_pasemi_msi_unmask_irq,
+	.eoi		= mpic_end_irq,
+	.set_type	= mpic_set_irq_type,
+	.set_affinity	= mpic_set_affinity,
+	.typename	= "PASEMI-MSI ",
+};
+
+static int pasemi_msi_check_device(struct pci_dev *pdev, int nvec, int type)
+{
+	if (type == PCI_CAP_ID_MSIX)
+		pr_debug("pasemi_msi: MSI-X untested, trying anyway\n");
+
+	return 0;
+}
+
+static void pasemi_msi_teardown_msi_irqs(struct pci_dev *pdev)
+{
+	struct msi_desc *entry;
+
+	pr_debug("pasemi_msi_teardown_msi_irqs, pdev %p\n", pdev);
+
+	list_for_each_entry(entry, &pdev->msi_list, list) {
+		if (entry->irq == NO_IRQ)
+			continue;
+
+		set_irq_msi(entry->irq, NULL);
+		mpic_msi_free_hwirqs(msi_mpic, virq_to_hw(entry->irq),
+				     ALLOC_CHUNK);
+		irq_dispose_mapping(entry->irq);
+	}
+
+	return;
+}
+
+static int pasemi_msi_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
+{
+	irq_hw_number_t hwirq;
+	unsigned int virq;
+	struct msi_desc *entry;
+	struct msi_msg msg;
+	u64 addr;
+
+	pr_debug("pasemi_msi_setup_msi_irqs, pdev %p nvec %d type %d\n",
+		 pdev, nvec, type);
+
+	msg.address_hi = 0;
+	msg.address_lo = PASEMI_MSI_ADDR;
+
+	list_for_each_entry(entry, &pdev->msi_list, list) {
+		/* Allocate 16 interrupts for now, since that's the grouping for
+		 * affinity. This can be changed later if it turns out 32 is too
+		 * few MSIs for someone, but restrictions will apply to how the
+		 * sources can be changed independently.
+		 */
+		hwirq = mpic_msi_alloc_hwirqs(msi_mpic, ALLOC_CHUNK);
+		if (hwirq < 0) {
+			pr_debug("pasemi_msi: failed allocating hwirq\n");
+			return hwirq;
+		}
+
+		virq = irq_create_mapping(msi_mpic->irqhost, hwirq);
+		if (virq == NO_IRQ) {
+			pr_debug("pasemi_msi: failed mapping hwirq 0x%lx\n", hwirq);
+			mpic_msi_free_hwirqs(msi_mpic, hwirq, ALLOC_CHUNK);
+			return -ENOSPC;
+		}
+
+		/* Vector on MSI is really an offset, the hardware adds
+		 * it to the value written at the magic address. So set
+		 * it to 0 to remain sane.
+		 */
+		mpic_set_vector(virq, 0);
+
+		set_irq_msi(virq, entry);
+		set_irq_chip(virq, &mpic_pasemi_msi_chip);
+		set_irq_type(virq, IRQ_TYPE_EDGE_RISING);
+
+		pr_debug("pasemi_msi: allocated virq 0x%x (hw 0x%lx) addr 0x%lx\n",
+			  virq, hwirq, addr);
+
+		/* Likewise, the device writes [0...511] into the target
+		 * register to generate MSI [512...1023]
+		 */
+		msg.data = hwirq-0x200;
+		write_msi_msg(virq, &msg);
+	}
+
+	return 0;
+}
+
+int mpic_pasemi_msi_init(struct mpic *mpic)
+{
+	int rc;
+
+	if (!mpic->irqhost->of_node ||
+	    !of_device_is_compatible(mpic->irqhost->of_node,
+				     "pasemi,pwrficient-openpic"))
+		return -ENODEV;
+
+	rc = mpic_msi_init_allocator(mpic);
+	if (rc) {
+		pr_debug("pasemi_msi: Error allocating bitmap!\n");
+		return rc;
+	}
+
+	pr_debug("pasemi_msi: Registering PA Semi MPIC MSI callbacks\n");
+
+	msi_mpic = mpic;
+	WARN_ON(ppc_md.setup_msi_irqs);
+	ppc_md.setup_msi_irqs = pasemi_msi_setup_msi_irqs;
+	ppc_md.teardown_msi_irqs = pasemi_msi_teardown_msi_irqs;
+	ppc_md.msi_check_device = pasemi_msi_check_device;
+
+	return 0;
+}