powerpc/xics: Rewrite XICS driver

This is a significant rework of the XICS driver, too significant to
conveniently break it up into a series of smaller patches to be honest.

The driver is moved to a more generic location to allow new platforms
to use it, and is broken up into separate ICP and ICS "backends". For
now we have the native and "hypervisor" ICP backends and one common
RTAS ICS backend.

The driver supports one ICP backend instanciation, and many ICS ones,
in order to accomodate future platforms with multiple possibly different
interrupt "sources" mechanisms.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

8 files changed, 1211 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/Kconfig b/arch/powerpc/sysdev/Kconfig
index 396582835cb5..cfc18770af79 100644
--- a/arch/powerpc/sysdev/Kconfig
+++ b/arch/powerpc/sysdev/Kconfig
@@ -12,3 +12,6 @@ config PPC_MSI_BITMAP
 	depends on PCI_MSI
 	default y if MPIC
 	default y if FSL_PCI
+
+source "arch/powerpc/sysdev/xics/Kconfig"
+
diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
index 1e0c933ef772..9516e7598573 100644
--- a/arch/powerpc/sysdev/Makefile
+++ b/arch/powerpc/sysdev/Makefile
@@ -57,3 +57,7 @@ obj-$(CONFIG_PPC_MPC52xx)	+= mpc5xxx_clocks.o
 ifeq ($(CONFIG_SUSPEND),y)
 obj-$(CONFIG_6xx)		+= 6xx-suspend.o
 endif
+
+subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
+
+obj-$(CONFIG_PPC_XICS)		+= xics/
diff --git a/arch/powerpc/sysdev/xics/Kconfig b/arch/powerpc/sysdev/xics/Kconfig
new file mode 100644
index 000000000000..123b8ddf2816
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/Kconfig
@@ -0,0 +1,12 @@
+config PPC_XICS
+       def_bool n
+
+config PPC_ICP_NATIVE
+       def_bool n
+
+config PPC_ICP_HV
+       def_bool n
+
+config PPC_ICS_RTAS
+       def_bool n
+
diff --git a/arch/powerpc/sysdev/xics/Makefile b/arch/powerpc/sysdev/xics/Makefile
new file mode 100644
index 000000000000..b75a6059337f
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/Makefile
@@ -0,0 +1,6 @@
+subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
+
+obj-y				+= xics-common.o
+obj-$(CONFIG_PPC_ICP_NATIVE)	+= icp-native.o
+obj-$(CONFIG_PPC_ICP_HV)	+= icp-hv.o
+obj-$(CONFIG_PPC_ICS_RTAS)	+= ics-rtas.o
diff --git a/arch/powerpc/sysdev/xics/icp-hv.c b/arch/powerpc/sysdev/xics/icp-hv.c
new file mode 100644
index 000000000000..b03d348b19a5
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/icp-hv.c
@@ -0,0 +1,184 @@
+/*
+ * Copyright 2011 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/types.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+
+#include <asm/smp.h>
+#include <asm/irq.h>
+#include <asm/errno.h>
+#include <asm/xics.h>
+#include <asm/io.h>
+#include <asm/hvcall.h>
+
+static inline unsigned int icp_hv_get_xirr(unsigned char cppr)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+	long rc;
+
+	rc = plpar_hcall(H_XIRR, retbuf, cppr);
+	if (rc != H_SUCCESS)
+		panic(" bad return code xirr - rc = %lx\n", rc);
+	return (unsigned int)retbuf[0];
+}
+
+static inline void icp_hv_set_xirr(unsigned int value)
+{
+	long rc = plpar_hcall_norets(H_EOI, value);
+	if (rc != H_SUCCESS)
+		panic("bad return code EOI - rc = %ld, value=%x\n", rc, value);
+}
+
+static inline void icp_hv_set_cppr(u8 value)
+{
+	long rc = plpar_hcall_norets(H_CPPR, value);
+	if (rc != H_SUCCESS)
+		panic("bad return code cppr - rc = %lx\n", rc);
+}
+
+static inline void icp_hv_set_qirr(int n_cpu , u8 value)
+{
+	long rc = plpar_hcall_norets(H_IPI, get_hard_smp_processor_id(n_cpu),
+				     value);
+	if (rc != H_SUCCESS)
+		panic("bad return code qirr - rc = %lx\n", rc);
+}
+
+static void icp_hv_eoi(struct irq_data *d)
+{
+	unsigned int hw_irq = (unsigned int)irq_data_to_hw(d);
+
+	iosync();
+	icp_hv_set_xirr((xics_pop_cppr() << 24) | hw_irq);
+}
+
+static void icp_hv_teardown_cpu(void)
+{
+	int cpu = smp_processor_id();
+
+	/* Clear any pending IPI */
+	icp_hv_set_qirr(cpu, 0xff);
+}
+
+static void icp_hv_flush_ipi(void)
+{
+	/* We take the ipi irq but and never return so we
+	 * need to EOI the IPI, but want to leave our priority 0
+	 *
+	 * should we check all the other interrupts too?
+	 * should we be flagging idle loop instead?
+	 * or creating some task to be scheduled?
+	 */
+
+	icp_hv_set_xirr((0x00 << 24) | XICS_IPI);
+}
+
+static unsigned int icp_hv_get_irq(void)
+{
+	unsigned int xirr = icp_hv_get_xirr(xics_cppr_top());
+	unsigned int vec = xirr & 0x00ffffff;
+	unsigned int irq;
+
+	if (vec == XICS_IRQ_SPURIOUS)
+		return NO_IRQ;
+
+	irq = irq_radix_revmap_lookup(xics_host, vec);
+	if (likely(irq != NO_IRQ)) {
+		xics_push_cppr(vec);
+		return irq;
+	}
+
+	/* We don't have a linux mapping, so have rtas mask it. */
+	xics_mask_unknown_vec(vec);
+
+	/* We might learn about it later, so EOI it */
+	icp_hv_set_xirr(xirr);
+
+	return NO_IRQ;
+}
+
+static void icp_hv_set_cpu_priority(unsigned char cppr)
+{
+	xics_set_base_cppr(cppr);
+	icp_hv_set_cppr(cppr);
+	iosync();
+}
+
+#ifdef CONFIG_SMP
+
+static inline void icp_hv_do_message(int cpu, int msg)
+{
+	unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
+
+	set_bit(msg, tgt);
+	mb();
+	icp_hv_set_qirr(cpu, IPI_PRIORITY);
+}
+
+static void icp_hv_message_pass(int target, int msg)
+{
+	unsigned int i;
+
+	if (target < NR_CPUS) {
+		icp_hv_do_message(target, msg);
+	} else {
+		for_each_online_cpu(i) {
+			if (target == MSG_ALL_BUT_SELF
+			    && i == smp_processor_id())
+				continue;
+			icp_hv_do_message(i, msg);
+		}
+	}
+}
+
+static irqreturn_t icp_hv_ipi_action(int irq, void *dev_id)
+{
+	int cpu = smp_processor_id();
+
+	icp_hv_set_qirr(cpu, 0xff);
+
+	return xics_ipi_dispatch(cpu);
+}
+
+#endif /* CONFIG_SMP */
+
+static const struct icp_ops icp_hv_ops = {
+	.get_irq	= icp_hv_get_irq,
+	.eoi		= icp_hv_eoi,
+	.set_priority	= icp_hv_set_cpu_priority,
+	.teardown_cpu	= icp_hv_teardown_cpu,
+	.flush_ipi	= icp_hv_flush_ipi,
+#ifdef CONFIG_SMP
+	.ipi_action	= icp_hv_ipi_action,
+	.message_pass	= icp_hv_message_pass,
+#endif
+};
+
+int icp_hv_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xicp");
+	if (!np)
+		np = of_find_node_by_type(NULL,
+				    "PowerPC-External-Interrupt-Presentation");
+	if (!np)
+		return -ENODEV;
+
+	icp_ops = &icp_hv_ops;
+
+	return 0;
+}
+
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
new file mode 100644
index 000000000000..be5e3d748edb
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -0,0 +1,312 @@
+/*
+ * Copyright 2011 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/types.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/spinlock.h>
+
+#include <asm/prom.h>
+#include <asm/io.h>
+#include <asm/smp.h>
+#include <asm/irq.h>
+#include <asm/errno.h>
+#include <asm/xics.h>
+
+struct icp_ipl {
+	union {
+		u32 word;
+		u8 bytes[4];
+	} xirr_poll;
+	union {
+		u32 word;
+		u8 bytes[4];
+	} xirr;
+	u32 dummy;
+	union {
+		u32 word;
+		u8 bytes[4];
+	} qirr;
+	u32 link_a;
+	u32 link_b;
+	u32 link_c;
+};
+
+static struct icp_ipl __iomem *icp_native_regs[NR_CPUS];
+
+static inline unsigned int icp_native_get_xirr(void)
+{
+	int cpu = smp_processor_id();
+
+	return in_be32(&icp_native_regs[cpu]->xirr.word);
+}
+
+static inline void icp_native_set_xirr(unsigned int value)
+{
+	int cpu = smp_processor_id();
+
+	out_be32(&icp_native_regs[cpu]->xirr.word, value);
+}
+
+static inline void icp_native_set_cppr(u8 value)
+{
+	int cpu = smp_processor_id();
+
+	out_8(&icp_native_regs[cpu]->xirr.bytes[0], value);
+}
+
+static inline void icp_native_set_qirr(int n_cpu, u8 value)
+{
+	out_8(&icp_native_regs[n_cpu]->qirr.bytes[0], value);
+}
+
+static void icp_native_set_cpu_priority(unsigned char cppr)
+{
+	xics_set_base_cppr(cppr);
+	icp_native_set_cppr(cppr);
+	iosync();
+}
+
+static void icp_native_eoi(struct irq_data *d)
+{
+	unsigned int hw_irq = (unsigned int)irq_data_to_hw(d);
+
+	iosync();
+	icp_native_set_xirr((xics_pop_cppr() << 24) | hw_irq);
+}
+
+static void icp_native_teardown_cpu(void)
+{
+	int cpu = smp_processor_id();
+
+	/* Clear any pending IPI */
+	icp_native_set_qirr(cpu, 0xff);
+}
+
+static void icp_native_flush_ipi(void)
+{
+	/* We take the ipi irq but and never return so we
+	 * need to EOI the IPI, but want to leave our priority 0
+	 *
+	 * should we check all the other interrupts too?
+	 * should we be flagging idle loop instead?
+	 * or creating some task to be scheduled?
+	 */
+
+	icp_native_set_xirr((0x00 << 24) | XICS_IPI);
+}
+
+static unsigned int icp_native_get_irq(void)
+{
+	unsigned int xirr = icp_native_get_xirr();
+	unsigned int vec = xirr & 0x00ffffff;
+	unsigned int irq;
+
+	if (vec == XICS_IRQ_SPURIOUS)
+		return NO_IRQ;
+
+	irq = irq_radix_revmap_lookup(xics_host, vec);
+	if (likely(irq != NO_IRQ)) {
+		xics_push_cppr(vec);
+		return irq;
+	}
+
+	/* We don't have a linux mapping, so have rtas mask it. */
+	xics_mask_unknown_vec(vec);
+
+	/* We might learn about it later, so EOI it */
+	icp_native_set_xirr(xirr);
+
+	return NO_IRQ;
+}
+
+#ifdef CONFIG_SMP
+
+static inline void icp_native_do_message(int cpu, int msg)
+{
+	unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
+
+	set_bit(msg, tgt);
+	mb();
+	icp_native_set_qirr(cpu, IPI_PRIORITY);
+}
+
+static void icp_native_message_pass(int target, int msg)
+{
+	unsigned int i;
+
+	if (target < NR_CPUS) {
+		icp_native_do_message(target, msg);
+	} else {
+		for_each_online_cpu(i) {
+			if (target == MSG_ALL_BUT_SELF
+			    && i == smp_processor_id())
+				continue;
+			icp_native_do_message(i, msg);
+		}
+	}
+}
+
+static irqreturn_t icp_native_ipi_action(int irq, void *dev_id)
+{
+	int cpu = smp_processor_id();
+
+	icp_native_set_qirr(cpu, 0xff);
+
+	return xics_ipi_dispatch(cpu);
+}
+
+#endif /* CONFIG_SMP */
+
+static int __init icp_native_map_one_cpu(int hw_id, unsigned long addr,
+					 unsigned long size)
+{
+	char *rname;
+	int i, cpu = -1;
+
+	/* This may look gross but it's good enough for now, we don't quite
+	 * have a hard -> linux processor id matching.
+	 */
+	for_each_possible_cpu(i) {
+		if (!cpu_present(i))
+			continue;
+		if (hw_id == get_hard_smp_processor_id(i)) {
+			cpu = i;
+			break;
+		}
+	}
+
+	/* Fail, skip that CPU. Don't print, it's normal, some XICS come up
+	 * with way more entries in there than you have CPUs
+	 */
+	if (cpu == -1)
+		return 0;
+
+	rname = kasprintf(GFP_KERNEL, "CPU %d [0x%x] Interrupt Presentation",
+			  cpu, hw_id);
+
+	if (!request_mem_region(addr, size, rname)) {
+		pr_warning("icp_native: Could not reserve ICP MMIO"
+			   " for CPU %d, interrupt server #0x%x\n",
+			   cpu, hw_id);
+		return -EBUSY;
+	}
+
+	icp_native_regs[cpu] = ioremap(addr, size);
+	if (!icp_native_regs[cpu]) {
+		pr_warning("icp_native: Failed ioremap for CPU %d, "
+			   "interrupt server #0x%x, addr %#lx\n",
+			   cpu, hw_id, addr);
+		release_mem_region(addr, size);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static int __init icp_native_init_one_node(struct device_node *np,
+					   unsigned int *indx)
+{
+	unsigned int ilen;
+	const u32 *ireg;
+	int i;
+	int reg_tuple_size;
+	int num_servers = 0;
+
+	/* This code does the theorically broken assumption that the interrupt
+	 * server numbers are the same as the hard CPU numbers.
+	 * This happens to be the case so far but we are playing with fire...
+	 * should be fixed one of these days. -BenH.
+	 */
+	ireg = of_get_property(np, "ibm,interrupt-server-ranges", &ilen);
+
+	/* Do that ever happen ? we'll know soon enough... but even good'old
+	 * f80 does have that property ..
+	 */
+	WARN_ON((ireg == NULL) || (ilen != 2*sizeof(u32)));
+
+	if (ireg) {
+		*indx = of_read_number(ireg, 1);
+		if (ilen >= 2*sizeof(u32))
+			num_servers = of_read_number(ireg + 1, 1);
+	}
+
+	ireg = of_get_property(np, "reg", &ilen);
+	if (!ireg) {
+		pr_err("icp_native: Can't find interrupt reg property");
+		return -1;
+	}
+
+	reg_tuple_size = (of_n_addr_cells(np) + of_n_size_cells(np)) * 4;
+	if (((ilen % reg_tuple_size) != 0)
+	    || (num_servers && (num_servers != (ilen / reg_tuple_size)))) {
+		pr_err("icp_native: ICP reg len (%d) != num servers (%d)",
+		       ilen / reg_tuple_size, num_servers);
+		return -1;
+	}
+
+	for (i = 0; i < (ilen / reg_tuple_size); i++) {
+		struct resource r;
+		int err;
+
+		err = of_address_to_resource(np, i, &r);
+		if (err) {
+			pr_err("icp_native: Could not translate ICP MMIO"
+			       " for interrupt server 0x%x (%d)\n", *indx, err);
+			return -1;
+		}
+
+		if (icp_native_map_one_cpu(*indx, r.start, r.end - r.start))
+			return -1;
+
+		(*indx)++;
+	}
+	return 0;
+}
+
+static const struct icp_ops icp_native_ops = {
+	.get_irq	= icp_native_get_irq,
+	.eoi		= icp_native_eoi,
+	.set_priority	= icp_native_set_cpu_priority,
+	.teardown_cpu	= icp_native_teardown_cpu,
+	.flush_ipi	= icp_native_flush_ipi,
+#ifdef CONFIG_SMP
+	.ipi_action	= icp_native_ipi_action,
+	.message_pass	= icp_native_message_pass,
+#endif
+};
+
+int icp_native_init(void)
+{
+	struct device_node *np;
+	u32 indx = 0;
+	int found = 0;
+
+	for_each_compatible_node(np, NULL, "ibm,ppc-xicp")
+		if (icp_native_init_one_node(np, &indx) == 0)
+			found = 1;
+	if (!found) {
+		for_each_node_by_type(np,
+			"PowerPC-External-Interrupt-Presentation") {
+				if (icp_native_init_one_node(np, &indx) == 0)
+					found = 1;
+		}
+	}
+
+	if (found == 0)
+		return -ENODEV;
+
+	icp_ops = &icp_native_ops;
+
+	return 0;
+}
diff --git a/arch/powerpc/sysdev/xics/ics-rtas.c b/arch/powerpc/sysdev/xics/ics-rtas.c
new file mode 100644
index 000000000000..5b3ee387e89d
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/ics-rtas.c
@@ -0,0 +1,229 @@
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/spinlock.h>
+#include <linux/msi.h>
+
+#include <asm/prom.h>
+#include <asm/smp.h>
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/errno.h>
+#include <asm/xics.h>
+#include <asm/rtas.h>
+
+/* RTAS service tokens */
+static int ibm_get_xive;
+static int ibm_set_xive;
+static int ibm_int_on;
+static int ibm_int_off;
+
+static int ics_rtas_map(struct ics *ics, unsigned int virq);
+static void ics_rtas_mask_unknown(struct ics *ics, unsigned long vec);
+static long ics_rtas_get_server(struct ics *ics, unsigned long vec);
+
+/* Only one global & state struct ics */
+static struct ics ics_rtas = {
+	.map		= ics_rtas_map,
+	.mask_unknown	= ics_rtas_mask_unknown,
+	.get_server	= ics_rtas_get_server,
+};
+
+static void ics_rtas_unmask_irq(struct irq_data *d)
+{
+	unsigned int hw_irq = (unsigned int)irq_data_to_hw(d);
+	int call_status;
+	int server;
+
+	pr_devel("xics: unmask virq %d [hw 0x%x]\n", d->irq, hw_irq);
+
+	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
+		return;
+
+	server = xics_get_irq_server(d->irq, d->affinity, 0);
+
+	call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, server,
+				DEFAULT_PRIORITY);
+	if (call_status != 0) {
+		printk(KERN_ERR
+			"%s: ibm_set_xive irq %u server %x returned %d\n",
+			__func__, hw_irq, server, call_status);
+		return;
+	}
+
+	/* Now unmask the interrupt (often a no-op) */
+	call_status = rtas_call(ibm_int_on, 1, 1, NULL, hw_irq);
+	if (call_status != 0) {
+		printk(KERN_ERR "%s: ibm_int_on irq=%u returned %d\n",
+			__func__, hw_irq, call_status);
+		return;
+	}
+}
+
+static unsigned int ics_rtas_startup(struct irq_data *d)
+{
+#ifdef CONFIG_PCI_MSI
+	/*
+	 * The generic MSI code returns with the interrupt disabled on the
+	 * card, using the MSI mask bits. Firmware doesn't appear to unmask
+	 * at that level, so we do it here by hand.
+	 */
+	if (d->msi_desc)
+		unmask_msi_irq(d);
+#endif
+	/* unmask it */
+	ics_rtas_unmask_irq(d);
+	return 0;
+}
+
+static void ics_rtas_mask_real_irq(unsigned int hw_irq)
+{
+	int call_status;
+
+	if (hw_irq == XICS_IPI)
+		return;
+
+	call_status = rtas_call(ibm_int_off, 1, 1, NULL, hw_irq);
+	if (call_status != 0) {
+		printk(KERN_ERR "%s: ibm_int_off irq=%u returned %d\n",
+			__func__, hw_irq, call_status);
+		return;
+	}
+
+	/* Have to set XIVE to 0xff to be able to remove a slot */
+	call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq,
+				xics_default_server, 0xff);
+	if (call_status != 0) {
+		printk(KERN_ERR "%s: ibm_set_xive(0xff) irq=%u returned %d\n",
+			__func__, hw_irq, call_status);
+		return;
+	}
+}
+
+static void ics_rtas_mask_irq(struct irq_data *d)
+{
+	unsigned int hw_irq = (unsigned int)irq_data_to_hw(d);
+
+	pr_devel("xics: mask virq %d [hw 0x%x]\n", d->irq, hw_irq);
+
+	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
+		return;
+	ics_rtas_mask_real_irq(hw_irq);
+}
+
+static int ics_rtas_set_affinity(struct irq_data *d,
+				 const struct cpumask *cpumask,
+				 bool force)
+{
+	unsigned int hw_irq = (unsigned int)irq_data_to_hw(d);
+	int status;
+	int xics_status[2];
+	int irq_server;
+
+	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
+		return -1;
+
+	status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq);
+
+	if (status) {
+		printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n",
+			__func__, hw_irq, status);
+		return -1;
+	}
+
+	irq_server = xics_get_irq_server(d->irq, cpumask, 1);
+	if (irq_server == -1) {
+		char cpulist[128];
+		cpumask_scnprintf(cpulist, sizeof(cpulist), cpumask);
+		printk(KERN_WARNING
+			"%s: No online cpus in the mask %s for irq %d\n",
+			__func__, cpulist, d->irq);
+		return -1;
+	}
+
+	status = rtas_call(ibm_set_xive, 3, 1, NULL,
+			   hw_irq, irq_server, xics_status[1]);
+
+	if (status) {
+		printk(KERN_ERR "%s: ibm,set-xive irq=%u returns %d\n",
+			__func__, hw_irq, status);
+		return -1;
+	}
+
+	return IRQ_SET_MASK_OK;
+}
+
+static struct irq_chip ics_rtas_irq_chip = {
+	.name = "XICS",
+	.irq_startup = ics_rtas_startup,
+	.irq_mask = ics_rtas_mask_irq,
+	.irq_unmask = ics_rtas_unmask_irq,
+	.irq_eoi = NULL, /* Patched at init time */
+	.irq_set_affinity = ics_rtas_set_affinity
+};
+
+static int ics_rtas_map(struct ics *ics, unsigned int virq)
+{
+	unsigned int hw_irq = (unsigned int)irq_map[virq].hwirq;
+	int status[2];
+	int rc;
+
+	if (WARN_ON(hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS))
+		return -EINVAL;
+
+	/* Check if RTAS knows about this interrupt */
+	rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq);
+	if (rc)
+		return -ENXIO;
+
+	irq_set_chip_and_handler(virq, &ics_rtas_irq_chip, handle_fasteoi_irq);
+	irq_set_chip_data(virq, &ics_rtas);
+
+	return 0;
+}
+
+static void ics_rtas_mask_unknown(struct ics *ics, unsigned long vec)
+{
+	ics_rtas_mask_real_irq(vec);
+}
+
+static long ics_rtas_get_server(struct ics *ics, unsigned long vec)
+{
+	int rc, status[2];
+
+	rc = rtas_call(ibm_get_xive, 1, 3, status, vec);
+	if (rc)
+		return -1;
+	return status[0];
+}
+
+int ics_rtas_init(void)
+{
+	ibm_get_xive = rtas_token("ibm,get-xive");
+	ibm_set_xive = rtas_token("ibm,set-xive");
+	ibm_int_on  = rtas_token("ibm,int-on");
+	ibm_int_off = rtas_token("ibm,int-off");
+
+	/* We enable the RTAS "ICS" if RTAS is present with the
+	 * appropriate tokens
+	 */
+	if (ibm_get_xive == RTAS_UNKNOWN_SERVICE ||
+	    ibm_set_xive == RTAS_UNKNOWN_SERVICE)
+		return -ENODEV;
+
+	/* We need to patch our irq chip's EOI to point to the
+	 * right ICP
+	 */
+	ics_rtas_irq_chip.irq_eoi = icp_ops->eoi;
+
+	/* Register ourselves */
+	xics_register_ics(&ics_rtas);
+
+	return 0;
+}
+
diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
new file mode 100644
index 000000000000..a2be84de5237
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/xics-common.c
@@ -0,0 +1,461 @@
+/*
+ * Copyright 2011 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/types.h>
+#include <linux/threads.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/debugfs.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <asm/prom.h>
+#include <asm/io.h>
+#include <asm/smp.h>
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/errno.h>
+#include <asm/rtas.h>
+#include <asm/xics.h>
+#include <asm/firmware.h>
+
+/* Globals common to all ICP/ICS implementations */
+const struct icp_ops	*icp_ops;
+
+unsigned int xics_default_server		= 0xff;
+unsigned int xics_default_distrib_server	= 0;
+unsigned int xics_interrupt_server_size		= 8;
+
+DEFINE_PER_CPU(struct xics_cppr, xics_cppr);
+
+struct irq_host *xics_host;
+
+static LIST_HEAD(ics_list);
+
+void xics_update_irq_servers(void)
+{
+	int i, j;
+	struct device_node *np;
+	u32 ilen;
+	const u32 *ireg;
+	u32 hcpuid;
+
+	/* Find the server numbers for the boot cpu. */
+	np = of_get_cpu_node(boot_cpuid, NULL);
+	BUG_ON(!np);
+
+	hcpuid = get_hard_smp_processor_id(boot_cpuid);
+	xics_default_server = hcpuid;
+
+	ireg = of_get_property(np, "ibm,ppc-interrupt-gserver#s", &ilen);
+	if (!ireg) {
+		of_node_put(np);
+		return;
+	}
+
+	i = ilen / sizeof(int);
+
+	/* Global interrupt distribution server is specified in the last
+	 * entry of "ibm,ppc-interrupt-gserver#s" property. Get the last
+	 * entry fom this property for current boot cpu id and use it as
+	 * default distribution server
+	 */
+	for (j = 0; j < i; j += 2) {
+		if (ireg[j] == hcpuid) {
+			xics_default_distrib_server = ireg[j+1];
+		}
+	}
+
+	of_node_put(np);
+}
+
+/* GIQ stuff, currently only supported on RTAS setups, will have
+ * to be sorted properly for bare metal
+ */
+void xics_set_cpu_giq(unsigned int gserver, unsigned int join)
+{
+#ifdef CONFIG_PPC_RTAS
+	int index;
+	int status;
+
+	if (!rtas_indicator_present(GLOBAL_INTERRUPT_QUEUE, NULL))
+		return;
+
+	index = (1UL << xics_interrupt_server_size) - 1 - gserver;
+
+	status = rtas_set_indicator_fast(GLOBAL_INTERRUPT_QUEUE, index, join);
+
+	WARN(status < 0, "set-indicator(%d, %d, %u) returned %d\n",
+	     GLOBAL_INTERRUPT_QUEUE, index, join, status);
+#endif
+}
+
+void xics_setup_cpu(void)
+{
+	icp_ops->set_priority(LOWEST_PRIORITY);
+
+	xics_set_cpu_giq(xics_default_distrib_server, 1);
+}
+
+void xics_mask_unknown_vec(unsigned int vec)
+{
+	struct ics *ics;
+
+	pr_err("Interrupt %u (real) is invalid, disabling it.\n", vec);
+
+	list_for_each_entry(ics, &ics_list, link)
+		ics->mask_unknown(ics, vec);
+}
+
+
+#ifdef CONFIG_SMP
+
+DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, xics_ipi_message);
+
+irqreturn_t xics_ipi_dispatch(int cpu)
+{
+	unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
+
+	mb();	/* order mmio clearing qirr */
+	while (*tgt) {
+		if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, tgt)) {
+			smp_message_recv(PPC_MSG_CALL_FUNCTION);
+		}
+		if (test_and_clear_bit(PPC_MSG_RESCHEDULE, tgt)) {
+			smp_message_recv(PPC_MSG_RESCHEDULE);
+		}
+		if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, tgt)) {
+			smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE);
+		}
+#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
+		if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, tgt)) {
+			smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
+		}
+#endif
+	}
+	return IRQ_HANDLED;
+}
+
+static void xics_request_ipi(void)
+{
+	unsigned int ipi;
+
+	ipi = irq_create_mapping(xics_host, XICS_IPI);
+	BUG_ON(ipi == NO_IRQ);
+
+	/*
+	 * IPIs are marked IRQF_DISABLED as they must run with irqs
+	 * disabled
+	 */
+	irq_set_handler(ipi, handle_percpu_irq);
+	BUG_ON(request_irq(ipi, icp_ops->ipi_action,
+			   IRQF_DISABLED|IRQF_PERCPU, "IPI", NULL));
+}
+
+int __init xics_smp_probe(void)
+{
+	/* Setup message_pass callback  based on which ICP is used */
+	smp_ops->message_pass = icp_ops->message_pass;
+
+	/* Register all the IPIs */
+	xics_request_ipi();
+
+	return cpumask_weight(cpu_possible_mask);
+}
+
+#endif /* CONFIG_SMP */
+
+void xics_teardown_cpu(void)
+{
+	struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
+
+	/*
+	 * we have to reset the cppr index to 0 because we're
+	 * not going to return from the IPI
+	 */
+	os_cppr->index = 0;
+	icp_ops->set_priority(0);
+	icp_ops->teardown_cpu();
+}
+
+void xics_kexec_teardown_cpu(int secondary)
+{
+	xics_teardown_cpu();
+
+	icp_ops->flush_ipi();
+
+	/*
+	 * Some machines need to have at least one cpu in the GIQ,
+	 * so leave the master cpu in the group.
+	 */
+	if (secondary)
+		xics_set_cpu_giq(xics_default_distrib_server, 0);
+}
+
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* Interrupts are disabled. */
+void xics_migrate_irqs_away(void)
+{
+	int cpu = smp_processor_id(), hw_cpu = hard_smp_processor_id();
+	unsigned int irq, virq;
+
+	/* If we used to be the default server, move to the new "boot_cpuid" */
+	if (hw_cpu == xics_default_server)
+		xics_update_irq_servers();
+
+	/* Reject any interrupt that was queued to us... */
+	icp_ops->set_priority(0);
+
+	/* Remove ourselves from the global interrupt queue */
+	xics_set_cpu_giq(xics_default_distrib_server, 0);
+
+	/* Allow IPIs again... */
+	icp_ops->set_priority(DEFAULT_PRIORITY);
+
+	for_each_irq(virq) {
+		struct irq_desc *desc;
+		struct irq_chip *chip;
+		long server;
+		unsigned long flags;
+		struct ics *ics;
+
+		/* We can't set affinity on ISA interrupts */
+		if (virq < NUM_ISA_INTERRUPTS)
+			continue;
+		if (irq_map[virq].host != xics_host)
+			continue;
+		irq = (unsigned int)irq_map[virq].hwirq;
+		/* We need to get IPIs still. */
+		if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
+			continue;
+		desc = irq_to_desc(virq);
+		/* We only need to migrate enabled IRQS */
+		if (!desc || !desc->action)
+			continue;
+		chip = irq_desc_get_chip(desc);
+		if (!chip || !chip->irq_set_affinity)
+			continue;
+
+		raw_spin_lock_irqsave(&desc->lock, flags);
+
+		/* Locate interrupt server */
+		server = -1;
+		ics = irq_get_chip_data(virq);
+		if (ics)
+			server = ics->get_server(ics, irq);
+		if (server < 0) {
+			printk(KERN_ERR "%s: Can't find server for irq %d\n",
+			       __func__, irq);
+			goto unlock;
+		}
+
+		/* We only support delivery to all cpus or to one cpu.
+		 * The irq has to be migrated only in the single cpu
+		 * case.
+		 */
+		if (server != hw_cpu)
+			goto unlock;
+
+		/* This is expected during cpu offline. */
+		if (cpu_online(cpu))
+			pr_warning("IRQ %u affinity broken off cpu %u\n",
+			       virq, cpu);
+
+		/* Reset affinity to all cpus */
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+		irq_set_affinity(virq, cpu_all_mask);
+		continue;
+unlock:
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+	}
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+#ifdef CONFIG_SMP
+/*
+ * For the moment we only implement delivery to all cpus or one cpu.
+ *
+ * If the requested affinity is cpu_all_mask, we set global affinity.
+ * If not we set it to the first cpu in the mask, even if multiple cpus
+ * are set. This is so things like irqbalance (which set core and package
+ * wide affinities) do the right thing.
+ */
+int xics_get_irq_server(unsigned int virq, const struct cpumask *cpumask,
+			unsigned int strict_check)
+{
+
+	if (!distribute_irqs)
+		return xics_default_server;
+
+	if (!cpumask_subset(cpu_possible_mask, cpumask)) {
+		int server = cpumask_first_and(cpu_online_mask, cpumask);
+
+		if (server < nr_cpu_ids)
+			return get_hard_smp_processor_id(server);
+
+		if (strict_check)
+			return -1;
+	}
+
+	/*
+	 * Workaround issue with some versions of JS20 firmware that
+	 * deliver interrupts to cpus which haven't been started. This
+	 * happens when using the maxcpus= boot option.
+	 */
+	if (cpumask_equal(cpu_online_mask, cpu_present_mask))
+		return xics_default_distrib_server;
+
+	return xics_default_server;
+}
+#endif /* CONFIG_SMP */
+
+static int xics_host_match(struct irq_host *h, struct device_node *node)
+{
+	/* IBM machines have interrupt parents of various funky types for things
+	 * like vdevices, events, etc... The trick we use here is to match
+	 * everything here except the legacy 8259 which is compatible "chrp,iic"
+	 */
+	return !of_device_is_compatible(node, "chrp,iic");
+}
+
+/* Dummies */
+static void xics_ipi_unmask(struct irq_data *d) { }
+static void xics_ipi_mask(struct irq_data *d) { }
+
+static struct irq_chip xics_ipi_chip = {
+	.name = "XICS",
+	.irq_eoi = NULL, /* Patched at init time */
+	.irq_mask = xics_ipi_mask,
+	.irq_unmask = xics_ipi_unmask,
+};
+
+static int xics_host_map(struct irq_host *h, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	struct ics *ics;
+
+	pr_devel("xics: map virq %d, hwirq 0x%lx\n", virq, hw);
+
+	/* Insert the interrupt mapping into the radix tree for fast lookup */
+	irq_radix_revmap_insert(xics_host, virq, hw);
+
+	/* They aren't all level sensitive but we just don't really know */
+	irq_set_status_flags(virq, IRQ_LEVEL);
+
+	/* Don't call into ICS for IPIs */
+	if (hw == XICS_IPI) {
+		irq_set_chip_and_handler(virq, &xics_ipi_chip,
+					 handle_fasteoi_irq);
+		return 0;
+	}
+
+	/* Let the ICS setup the chip data */
+	list_for_each_entry(ics, &ics_list, link)
+		if (ics->map(ics, virq) == 0)
+			break;
+	return 0;
+}
+
+static int xics_host_xlate(struct irq_host *h, struct device_node *ct,
+			   const u32 *intspec, unsigned int intsize,
+			   irq_hw_number_t *out_hwirq, unsigned int *out_flags)
+
+{
+	/* Current xics implementation translates everything
+	 * to level. It is not technically right for MSIs but this
+	 * is irrelevant at this point. We might get smarter in the future
+	 */
+	*out_hwirq = intspec[0];
+	*out_flags = IRQ_TYPE_LEVEL_LOW;
+
+	return 0;
+}
+
+static struct irq_host_ops xics_host_ops = {
+	.match = xics_host_match,
+	.map = xics_host_map,
+	.xlate = xics_host_xlate,
+};
+
+static void __init xics_init_host(void)
+{
+	xics_host = irq_alloc_host(NULL, IRQ_HOST_MAP_TREE, 0, &xics_host_ops,
+				   XICS_IRQ_SPURIOUS);
+	BUG_ON(xics_host == NULL);
+	irq_set_default_host(xics_host);
+}
+
+void __init xics_register_ics(struct ics *ics)
+{
+	list_add(&ics->link, &ics_list);
+}
+
+static void __init xics_get_server_size(void)
+{
+	struct device_node *np;
+	const u32 *isize;
+
+	/* We fetch the interrupt server size from the first ICS node
+	 * we find if any
+	 */
+	np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xics");
+	if (!np)
+		return;
+	isize = of_get_property(np, "ibm,interrupt-server#-size", NULL);
+	if (!isize)
+		return;
+	xics_interrupt_server_size = *isize;
+	of_node_put(np);
+}
+
+void __init xics_init(void)
+{
+	int rc = -1;
+
+	/* Fist locate ICP */
+#ifdef CONFIG_PPC_ICP_HV
+	if (firmware_has_feature(FW_FEATURE_LPAR))
+		rc = icp_hv_init();
+#endif
+#ifdef CONFIG_PPC_ICP_NATIVE
+	if (rc < 0)
+		rc = icp_native_init();
+#endif
+	if (rc < 0) {
+		pr_warning("XICS: Cannot find a Presentation Controller !\n");
+		return;
+	}
+
+	/* Copy get_irq callback over to ppc_md */
+	ppc_md.get_irq = icp_ops->get_irq;
+
+	/* Patch up IPI chip EOI */
+	xics_ipi_chip.irq_eoi = icp_ops->eoi;
+
+	/* Now locate ICS */
+#ifdef CONFIG_PPC_ICS_RTAS
+	rc = ics_rtas_init();
+#endif
+	if (rc < 0)
+		pr_warning("XICS: Cannot find a Source Controller !\n");
+
+	/* Initialize common bits */
+	xics_get_server_size();
+	xics_update_irq_servers();
+	xics_init_host();
+	xics_setup_cpu();
+}