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>

1 files changed, 312 insertions, 0 deletions

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;
+}