powerpc/mpic: FSL MPIC error interrupt support.

All SOC device error interrupts are muxed and delivered to the core
as a single MPIC error interrupt. Currently all the device drivers
requiring access to device errors have to register for the MPIC error
interrupt as a shared interrupt.

With this patch we add interrupt demuxing capability in the mpic driver,
allowing device drivers to register for their individual error interrupts.
This is achieved by handling error interrupts in a cascaded fashion.

MPIC error interrupt is handled by the "error_int_handler", which
subsequently demuxes it using the EISR and delivers it to the respective
drivers.

The error interrupt capability is dependent on the MPIC EIMR register,
which was introduced in FSL MPIC version 4.1 (P4080 rev2). So, error
interrupt demuxing capability is dependent on the MPIC version and can
be used for versions >= 4.1.

Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 43 insertions, 1 deletions

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 7e32db7e7b0d..9c6e535daad2 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1026,6 +1026,9 @@ static int mpic_host_map(struct irq_domain *h, unsigned int virq,
                 return 0;
         }
 
+        if (mpic_map_error_int(mpic, virq, hw))
+                return 0;
+
         if (hw >= mpic->num_sources)
                 return -EINVAL;
 
@@ -1085,7 +1088,16 @@ static int mpic_host_xlate(struct irq_domain *h, struct device_node *ct,
                  */
                 switch (intspec[2]) {
                 case 0:
-                case 1: /* no EISR/EIMR support for now, treat as shared IRQ */
+                        break;
+                case 1:
+                        if (!(mpic->flags & MPIC_FSL_HAS_EIMR))
+                                break;
+
+                        if (intspec[3] >= ARRAY_SIZE(mpic->err_int_vecs))
+                                return -EINVAL;
+
+                        *out_hwirq = mpic->err_int_vecs[intspec[3]];
+
                         break;
                 case 2:
                         if (intspec[0] >= ARRAY_SIZE(mpic->ipi_vecs))
@@ -1302,6 +1314,9 @@ struct mpic * __init mpic_alloc(struct device_node *node,
         mpic_map(mpic, mpic->paddr, &mpic->tmregs, MPIC_INFO(TIMER_BASE), 0x1000);
 
         if (mpic->flags & MPIC_FSL) {
+                u32 brr1, version;
+                int ret;
+
                 /*
                  * Yes, Freescale really did put global registers in the
                  * magic per-cpu area -- and they don't even show up in the
@@ -1309,6 +1324,29 @@ struct mpic * __init mpic_alloc(struct device_node *node,
                  */
                 mpic_map(mpic, mpic->paddr, &mpic->thiscpuregs,
                          MPIC_CPU_THISBASE, 0x1000);
+
+                brr1 = _mpic_read(mpic->reg_type, &mpic->thiscpuregs,
+                                MPIC_FSL_BRR1);
+                version = brr1 & MPIC_FSL_BRR1_VER;
+
+                /* Error interrupt mask register (EIMR) is required for
+                 * handling individual device error interrupts. EIMR
+                 * was added in MPIC version 4.1.
+                 *
+                 * Over here we reserve vector number space for error
+                 * interrupt vectors. This space is stolen from the
+                 * global vector number space, as in case of ipis
+                 * and timer interrupts.
+                 *
+                 * Available vector space = intvec_top - 12, where 12
+                 * is the number of vectors which have been consumed by
+                 * ipis and timer interrupts.
+                 */
+                if (version >= 0x401) {
+                        ret = mpic_setup_error_int(mpic, intvec_top - 12);
+                        if (ret)
+                                return NULL;
+                }
         }
 
         /* Reset */
@@ -1474,6 +1512,10 @@ void __init mpic_init(struct mpic *mpic)
                         num_timers = 8;
         }
 
+        /* FSL mpic error interrupt intialization */
+        if (mpic->flags & MPIC_FSL_HAS_EIMR)
+                mpic_err_int_init(mpic, MPIC_FSL_ERR_INT);
+
         /* Initialize timers to our reserved vectors and mask them for now */
         for (i = 0; i < num_timers; i++) {
                 unsigned int offset = mpic_tm_offset(mpic, i);