powerpc: iSeries has only 256 IRQs

The iSeries Hypervisor only allows us to specify IRQ numbers up to 255 (it
has a u8 field to pass it in).  This patch allows platforms to specify a
maximum to the virtual IRQ numbers we will use and has iSeries set that
to 255.  If not set, the maximum is NR_IRQS - 1 (as before).

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index bb5c9501234c8364c855cf11d7e363983603ef61..57d560c68897b08bcd85003eaefbf1c4442ad0ac 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -272,18 +272,26 @@ unsigned int virt_irq_to_real_map[NR_IRQS];
  * Don't use virtual irqs 0, 1, 2 for devices.
  * The pcnet32 driver considers interrupt numbers < 2 to be invalid,
  * and 2 is the XICS IPI interrupt.
- * We limit virtual irqs to 17 less than NR_IRQS so that when we
- * offset them by 16 (to reserve the first 16 for ISA interrupts)
- * we don't end up with an interrupt number >= NR_IRQS.
+ * We limit virtual irqs to __irq_offet_value less than virt_irq_max so
+ * that when we offset them we don't end up with an interrupt
+ * number >= virt_irq_max.
  */
 #define MIN_VIRT_IRQ   3
-#define MAX_VIRT_IRQ   (NR_IRQS - NUM_ISA_INTERRUPTS - 1)
-#define NR_VIRT_IRQS   (MAX_VIRT_IRQ - MIN_VIRT_IRQ + 1)
+
+unsigned int virt_irq_max;
+static unsigned int max_virt_irq;
+static unsigned int nr_virt_irqs;
 
 void
 virt_irq_init(void)
 {
        int i;
+
+       if ((virt_irq_max == 0) || (virt_irq_max > (NR_IRQS - 1)))
+               virt_irq_max = NR_IRQS - 1;
+       max_virt_irq = virt_irq_max - __irq_offset_value;
+       nr_virt_irqs = max_virt_irq - MIN_VIRT_IRQ + 1;
+
        for (i = 0; i < NR_IRQS; i++)
                virt_irq_to_real_map[i] = UNDEFINED_IRQ;
 }
@@ -308,17 +316,17 @@ int virt_irq_create_mapping(unsigned int real_irq)
                return real_irq;
        }
 
-       /* map to a number between MIN_VIRT_IRQ and MAX_VIRT_IRQ */
+       /* map to a number between MIN_VIRT_IRQ and max_virt_irq */
        virq = real_irq;
-       if (virq > MAX_VIRT_IRQ)
-               virq = (virq % NR_VIRT_IRQS) + MIN_VIRT_IRQ;
+       if (virq > max_virt_irq)
+               virq = (virq % nr_virt_irqs) + MIN_VIRT_IRQ;
 
        /* search for this number or a free slot */
        first_virq = virq;
        while (virt_irq_to_real_map[virq] != UNDEFINED_IRQ) {
                if (virt_irq_to_real_map[virq] == real_irq)
                        return virq;
-               if (++virq > MAX_VIRT_IRQ)
+               if (++virq > max_virt_irq)
                        virq = MIN_VIRT_IRQ;
                if (virq == first_virq)
                        goto nospace;   /* oops, no free slots */
@@ -330,8 +338,8 @@ int virt_irq_create_mapping(unsigned int real_irq)
  nospace:
        if (!warned) {
                printk(KERN_CRIT "Interrupt table is full\n");
-               printk(KERN_CRIT "Increase NR_IRQS (currently %d) "
-                      "in your kernel sources and rebuild.\n", NR_IRQS);
+               printk(KERN_CRIT "Increase virt_irq_max (currently %d) "
+                      "in your kernel sources and rebuild.\n", virt_irq_max);
                warned = 1;
        }
        return NO_IRQ;
@@ -349,8 +357,8 @@ unsigned int real_irq_to_virt_slowpath(unsigned int real_irq)
 
        virq = real_irq;
 
-       if (virq > MAX_VIRT_IRQ)
-               virq = (virq % NR_VIRT_IRQS) + MIN_VIRT_IRQ;
+       if (virq > max_virt_irq)
+               virq = (virq % nr_virt_irqs) + MIN_VIRT_IRQ;
 
        first_virq = virq;
 
@@ -360,7 +368,7 @@ unsigned int real_irq_to_virt_slowpath(unsigned int real_irq)
 
                virq++;
 
-               if (virq >= MAX_VIRT_IRQ)
+               if (virq >= max_virt_irq)
                        virq = 0;
 
        } while (first_virq != virq);

diff --git a/arch/powerpc/platforms/iseries/setup.c b/arch/powerpc/platforms/iseries/setup.c
index 6ce8a404ba6b2b9cd8f5ccbccbb1888b441df1ba..a6fd9bedb0741b533fc207650a128ef1c35070ec 100644 (file)
--- a/arch/powerpc/platforms/iseries/setup.c
+++ b/arch/powerpc/platforms/iseries/setup.c
@@ -54,6 +54,7 @@
 #include <asm/iseries/hv_lp_event.h>
 #include <asm/iseries/lpar_map.h>
 #include <asm/udbg.h>
+#include <asm/irq.h>
 
 #include "naca.h"
 #include "setup.h"
@@ -684,6 +685,12 @@ static int __init iseries_probe(void)
        powerpc_firmware_features |= FW_FEATURE_ISERIES;
        powerpc_firmware_features |= FW_FEATURE_LPAR;
 
+       /*
+        * The Hypervisor only allows us up to 256 interrupt
+        * sources (the irq number is passed in a u8).
+        */
+       virt_irq_max = 255;
+
        return 1;
 }
 

diff --git a/include/asm-powerpc/irq.h b/include/asm-powerpc/irq.h
index 51f87d9993b6d09e2833f2ff403a58783c61d7bf..7bc6d73b2823c5032852d3b1ae57b8db569795e8 100644 (file)
--- a/include/asm-powerpc/irq.h
+++ b/include/asm-powerpc/irq.h
@@ -54,6 +54,13 @@
  */
 extern unsigned int virt_irq_to_real_map[NR_IRQS];
 
+/* The maximum virtual IRQ number that we support.  This
+ * can be set by the platform and will be reduced by the
+ * value of __irq_offset_value.  It defaults to and is
+ * capped by (NR_IRQS - 1).
+ */
+extern unsigned int virt_irq_max;
+
 /* Create a mapping for a real_irq if it doesn't already exist.
  * Return the virtual irq as a convenience.
  */