[PATCH] Initial generic hypertransport interrupt support

This patch implements two functions ht_create_irq and ht_destroy_irq for
use by drivers.  Several other functions are implemented as helpers for
arch specific irq_chip handlers.

The driver for the card I tested this on isn't yet ready to be merged.
However this code is and hypertransport irqs are in use in a few other
places in the kernel.  Not that any of this will get merged before 2.6.19

Because the ipath-ht400 is slightly out of spec this code will need to be
generalized to work there.

I think all of the powerpc uses are for a plain interrupt controller in a
chipset so support for native hypertransport devices is a little less
interesting.

However I think this is a half way decent model on how to separate arch
specific and generic helper code, and I think this is a functional model of
how to get the architecture dependencies out of the msi code.

[akpm@osdl.org: Kconfig fix]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg KH <greg@kroah.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 199 insertions, 0 deletions

diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index c27e782..0af6d72 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -52,3 +52,12 @@ config PCI_DEBUG
 
 	  When in doubt, say N.
 
+config HT_IRQ
+	bool "Interrupts on hypertransport devices"
+	default y
+	depends on PCI_MSI
+	depends on X86_LOCAL_APIC && X86_IO_APIC
+	help
+	   This allows native hypertransport devices to use interrupts.
+
+	   If unsure say Y.
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 983d0f8..2752c57 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_PPC32) += setup-irq.o
 obj-$(CONFIG_PPC64) += setup-bus.o
 obj-$(CONFIG_MIPS) += setup-bus.o setup-irq.o
 obj-$(CONFIG_X86_VISWS) += setup-irq.o
+obj-$(CONFIG_HT_IRQ) += htirq.o
 
 msiobj-y := msi.o
 msiobj-$(CONFIG_IA64) += msi-apic.o
diff --git a/drivers/pci/htirq.c b/drivers/pci/htirq.c
new file mode 100644
index 0000000..4ba4635
--- /dev/null
+++ b/drivers/pci/htirq.c
@@ -0,0 +1,189 @@
+/*
+ * File:	htirq.c
+ * Purpose:	Hypertransport Interrupt Capability
+ *
+ * Copyright (C) 2006 Linux Networx
+ * Copyright (C) Eric Biederman <ebiederman@lnxi.com>
+ */
+
+#include <linux/irq.h>
+#include <linux/pci.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/gfp.h>
+
+/* Global ht irq lock.
+ *
+ * This is needed to serialize access to the data port in hypertransport
+ * irq capability.
+ *
+ * With multiple simultaneous hypertransport irq devices it might pay
+ * to make this more fine grained.  But start with simple, stupid, and correct.
+ */
+static DEFINE_SPINLOCK(ht_irq_lock);
+
+struct ht_irq_cfg {
+	struct pci_dev *dev;
+	unsigned pos;
+	unsigned idx;
+};
+
+void write_ht_irq_low(unsigned int irq, u32 data)
+{
+	struct ht_irq_cfg *cfg = get_irq_data(irq);
+	unsigned long flags;
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
+	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+}
+
+void write_ht_irq_high(unsigned int irq, u32 data)
+{
+	struct ht_irq_cfg *cfg = get_irq_data(irq);
+	unsigned long flags;
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
+	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+}
+
+u32 read_ht_irq_low(unsigned int irq)
+{
+	struct ht_irq_cfg *cfg = get_irq_data(irq);
+	unsigned long flags;
+	u32 data;
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
+	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+	return data;
+}
+
+u32 read_ht_irq_high(unsigned int irq)
+{
+	struct ht_irq_cfg *cfg = get_irq_data(irq);
+	unsigned long flags;
+	u32 data;
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
+	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+	return data;
+}
+
+void mask_ht_irq(unsigned int irq)
+{
+	struct ht_irq_cfg *cfg;
+	unsigned long flags;
+	u32 data;
+
+	cfg = get_irq_data(irq);
+
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
+	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
+	data |= 1;
+	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+}
+
+void unmask_ht_irq(unsigned int irq)
+{
+	struct ht_irq_cfg *cfg;
+	unsigned long flags;
+	u32 data;
+
+	cfg = get_irq_data(irq);
+
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
+	pci_read_config_dword(cfg->dev, cfg->pos + 4, &data);
+	data &= ~1;
+	pci_write_config_dword(cfg->dev, cfg->pos + 4, data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+}
+
+/**
+ * ht_create_irq - create an irq and attach it to a device.
+ * @dev: The hypertransport device to find the irq capability on.
+ * @idx: Which of the possible irqs to attach to.
+ *
+ * ht_create_irq is needs to be called for all hypertransport devices
+ * that generate irqs.
+ *
+ * The irq number of the new irq or a negative error value is returned.
+ */
+int ht_create_irq(struct pci_dev *dev, int idx)
+{
+	struct ht_irq_cfg *cfg;
+	unsigned long flags;
+	u32 data;
+	int max_irq;
+	int pos;
+	int irq;
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_HT);
+	while (pos) {
+		u8 subtype;
+		pci_read_config_byte(dev, pos + 3, &subtype);
+		if (subtype == HT_CAPTYPE_IRQ)
+			break;
+		pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_HT);
+	}
+	if (!pos)
+		return -EINVAL;
+
+	/* Verify the idx I want to use is in range */
+	spin_lock_irqsave(&ht_irq_lock, flags);
+	pci_write_config_byte(dev, pos + 2, 1);
+	pci_read_config_dword(dev, pos + 4, &data);
+	spin_unlock_irqrestore(&ht_irq_lock, flags);
+
+	max_irq = (data >> 16) & 0xff;
+	if ( idx > max_irq)
+		return -EINVAL;
+
+	cfg = kmalloc(sizeof(*cfg), GFP_KERNEL);
+	if (!cfg)
+		return -ENOMEM;
+
+	cfg->dev = dev;
+	cfg->pos = pos;
+	cfg->idx = 0x10 + (idx * 2);
+
+	irq = create_irq();
+	if (irq < 0) {
+		kfree(cfg);
+		return -EBUSY;
+	}
+	set_irq_data(irq, cfg);
+
+	if (arch_setup_ht_irq(irq, dev) < 0) {
+		ht_destroy_irq(irq);
+		return -EBUSY;
+	}
+
+	return irq;
+}
+
+/**
+ * ht_destroy_irq - destroy an irq created with ht_create_irq
+ *
+ * This reverses ht_create_irq removing the specified irq from
+ * existence.  The irq should be free before this happens.
+ */
+void ht_destroy_irq(unsigned int irq)
+{
+	struct ht_irq_cfg *cfg;
+
+	cfg = get_irq_data(irq);
+	set_irq_chip(irq, NULL);
+	set_irq_data(irq, NULL);
+	destroy_irq(irq);
+
+	kfree(cfg);
+}
+
+EXPORT_SYMBOL(ht_create_irq);
+EXPORT_SYMBOL(ht_destroy_irq);