sparc32,leon: add support for extended interrupt controller

The extended IRQ controller gives the LEON 16 more IRQs.

The patch installs a custom handler for the exetended controller
IRQ, where a register is read and the "real" IRQ causing IRQ is
determined.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 71 insertions, 24 deletions

diff --git a/arch/sparc/kernel/leon_kernel.c b/arch/sparc/kernel/leon_kernel.c
index 390e4696276..210f4a0a845 100644
--- a/arch/sparc/kernel/leon_kernel.c
+++ b/arch/sparc/kernel/leon_kernel.c
@@ -19,6 +19,7 @@
 #include <asm/leon_amba.h>
 #include <asm/traps.h>
 #include <asm/cacheflush.h>
+#include <asm/smp.h>
 
 #include "prom.h"
 #include "irq.h"
@@ -36,37 +37,51 @@ static DEFINE_SPINLOCK(leon_irq_lock);
 unsigned long leon3_gptimer_irq; /* interrupt controller irq number */
 unsigned long leon3_gptimer_idx; /* Timer Index (0..6) within Timer Core */
 unsigned int sparc_leon_eirq;
-#define LEON_IMASK ((&leon3_irqctrl_regs->mask[0]))
+#define LEON_IMASK (&leon3_irqctrl_regs->mask[0])
+#define LEON_IACK (&leon3_irqctrl_regs->iclear)
+#define LEON_DO_ACK_HW 1
 
-/* Return the IRQ of the pending IRQ on the extended IRQ controller */
-int sparc_leon_eirq_get(int eirq, int cpu)
+/* Return the last ACKed IRQ by the Extended IRQ controller. It has already
+ * been (automatically) ACKed when the CPU takes the trap.
+ */
+static inline unsigned int leon_eirq_get(int cpu)
 {
         return LEON3_BYPASS_LOAD_PA(&leon3_irqctrl_regs->intid[cpu]) & 0x1f;
 }
 
-irqreturn_t sparc_leon_eirq_isr(int dummy, void *dev_id)
+/* Handle one or multiple IRQs from the extended interrupt controller */
+static void leon_handle_ext_irq(unsigned int irq, struct irq_desc *desc)
 {
-        printk(KERN_ERR "sparc_leon_eirq_isr: ERROR EXTENDED IRQ\n");
-        return IRQ_HANDLED;
+        unsigned int eirq;
+        int cpu = hard_smp_processor_id();
+
+        eirq = leon_eirq_get(cpu);
+        if ((eirq & 0x10) && irq_map[eirq]->irq) /* bit4 tells if IRQ happened */
+                generic_handle_irq(irq_map[eirq]->irq);
 }
 
 /* The extended IRQ controller has been found, this function registers it */
-void sparc_leon_eirq_register(int eirq)
+void leon_eirq_setup(unsigned int eirq)
 {
-        int irq;
+        unsigned long mask, oldmask;
+        unsigned int veirq;
 
-        /* Register a "BAD" handler for this interrupt, it should never happen */
-        irq = request_irq(eirq, sparc_leon_eirq_isr,
-                          (IRQF_DISABLED | SA_STATIC_ALLOC), "extirq", NULL);
-
-        if (irq) {
-                printk(KERN_ERR
-                       "sparc_leon_eirq_register: unable to attach IRQ%d\n",
-                       eirq);
-        } else {
-                sparc_leon_eirq = eirq;
+        if (eirq < 1 || eirq > 0xf) {
+                printk(KERN_ERR "LEON EXT IRQ NUMBER BAD: %d\n", eirq);
+                return;
         }
 
+        veirq = leon_build_device_irq(eirq, leon_handle_ext_irq, "extirq", 0);
+
+        /*
+         * Unmask the Extended IRQ, the IRQs routed through the Ext-IRQ
+         * controller have a mask-bit of their own, so this is safe.
+         */
+        irq_link(veirq);
+        mask = 1 << eirq;
+        oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK);
+        LEON3_BYPASS_STORE_PA(LEON_IMASK, (oldmask | mask));
+        sparc_leon_eirq = eirq;
 }
 
 static inline unsigned long get_irqmask(unsigned int irq)
@@ -119,16 +134,33 @@ static void leon_shutdown_irq(struct irq_data *data)
         irq_unlink(data->irq);
 }
 
+/* Used by external level sensitive IRQ handlers on the LEON: ACK IRQ ctrl */
+static void leon_eoi_irq(struct irq_data *data)
+{
+        unsigned long mask = (unsigned long)data->chip_data;
+
+        if (mask & LEON_DO_ACK_HW)
+                LEON3_BYPASS_STORE_PA(LEON_IACK, mask & ~LEON_DO_ACK_HW);
+}
+
 static struct irq_chip leon_irq = {
         .name           = "leon",
         .irq_startup    = leon_startup_irq,
         .irq_shutdown   = leon_shutdown_irq,
         .irq_mask       = leon_mask_irq,
         .irq_unmask     = leon_unmask_irq,
+        .irq_eoi        = leon_eoi_irq,
 };
 
-static unsigned int leon_build_device_irq(struct platform_device *op,
-                                          unsigned int real_irq)
+/*
+ * Build a LEON IRQ for the edge triggered LEON IRQ controller:
+ *  Edge (normal) IRQ           - handle_simple_irq, ack=DONT-CARE, never ack
+ *  Level IRQ (PCI|Level-GPIO)  - handle_fasteoi_irq, ack=1, ack after ISR
+ *  Per-CPU Edge                - handle_percpu_irq, ack=0
+ */
+unsigned int leon_build_device_irq(unsigned int real_irq,
+                                    irq_flow_handler_t flow_handler,
+                                    const char *name, int do_ack)
 {
         unsigned int irq;
         unsigned long mask;
@@ -142,17 +174,26 @@ static unsigned int leon_build_device_irq(struct platform_device *op,
         if (irq == 0)
                 goto out;
 
+        if (do_ack)
+                mask |= LEON_DO_ACK_HW;
+
         irq_set_chip_and_handler_name(irq, &leon_irq,
-                                      handle_simple_irq, "edge");
+                                      flow_handler, name);
         irq_set_chip_data(irq, (void *)mask);
 
 out:
         return irq;
 }
 
+static unsigned int _leon_build_device_irq(struct platform_device *op,
+                                           unsigned int real_irq)
+{
+        return leon_build_device_irq(real_irq, handle_simple_irq, "edge", 0);
+}
+
 void __init leon_init_timers(irq_handler_t counter_fn)
 {
-        int irq;
+        int irq, eirq;
         struct device_node *rootnp, *np, *nnp;
         struct property *pp;
         int len;
@@ -262,11 +303,17 @@ void __init leon_init_timers(irq_handler_t counter_fn)
                 icsel = LEON3_BYPASS_LOAD_PA(&leon3_irqctrl_regs->icsel[cpu/8]);
                 icsel = (icsel >> ((7 - (cpu&0x7)) * 4)) & 0xf;
                 leon3_irqctrl_regs += icsel;
+
+                /* Probe extended IRQ controller */
+                eirq = (LEON3_BYPASS_LOAD_PA(&leon3_irqctrl_regs->mpstatus)
+                        >> 16) & 0xf;
+                if (eirq != 0)
+                        leon_eirq_setup(eirq);
         } else {
                 goto bad;
         }
 
-        irq = leon_build_device_irq(NULL, leon3_gptimer_irq + leon3_gptimer_idx);
+        irq = _leon_build_device_irq(NULL, leon3_gptimer_irq+leon3_gptimer_idx);
         err = request_irq(irq, counter_fn, IRQF_TIMER, "timer", NULL);
 
         if (err) {
@@ -394,7 +441,7 @@ void leon_enable_irq_cpu(unsigned int irq_nr, unsigned int cpu)
 void __init leon_init_IRQ(void)
 {
         sparc_irq_config.init_timers      = leon_init_timers;
-        sparc_irq_config.build_device_irq = leon_build_device_irq;
+        sparc_irq_config.build_device_irq = _leon_build_device_irq;
 
         BTFIXUPSET_CALL(clear_clock_irq, leon_clear_clock_irq,
                         BTFIXUPCALL_NORM);