When an SPI irq line changes level, this causes what the spec
describes as SET_LEVEL, SET_EDGE or CLEAR events.  These also happen
when the trigger mode is reconfigured, or when software requests a
manual resample via the IRS_SPI_RESAMPLER register.

SET_LEVEL and SET_EDGE events make the interrupt pending, and update
its handler mode to match its trigger mode.  CLEAR events make the
interrupt no longer pending.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
---
 hw/intc/arm_gicv5.c  | 59 ++++++++++++++++++++++++++++++++++++++++++++
 hw/intc/trace-events |  1 +
 2 files changed, 60 insertions(+)

diff --git a/hw/intc/arm_gicv5.c b/hw/intc/arm_gicv5.c
index 6ff3a79745..bc887233f5 100644
--- a/hw/intc/arm_gicv5.c
+++ b/hw/intc/arm_gicv5.c
@@ -946,6 +946,28 @@ static void irs_ist_baser_write(GICv5 *s, GICv5Domain domain, uint64_t value)
     }
 }
 
+static void spi_sample(GICv5SPIState *spi)
+{
+    /*
+     * Sample the state of the SPI input line; this generates
+     * SET_EDGE, SET_LEVEL or CLEAR events which update the SPI's
+     * pending state and handling mode per R_HHKMN.  The logic is the
+     * same for "the input line changed" (R_QBXXV) and "software asked
+     * us to resample" (R_DMTFM).
+     */
+    if (spi->level) {
+        /*
+         * SET_LEVEL or SET_EDGE: interrupt becomes pending, and the
+         * handling mode is updated to match the trigger mode.
+         */
+        spi->pending = true;
+        spi->hm = spi->tm == GICV5_TRIGGER_EDGE ? GICV5_EDGE : GICV5_LEVEL;
+    } else if (spi->tm == GICV5_TRIGGER_LEVEL) {
+        /* falling edges only trigger a CLEAR event for level-triggered */
+        spi->pending = false;
+    }
+}
+
 static bool config_readl(GICv5 *s, GICv5Domain domain, hwaddr offset,
                          uint64_t *data, MemTxAttrs attrs)
 {
@@ -1096,7 +1118,24 @@ static bool config_writel(GICv5 *s, GICv5Domain domain, hwaddr offset,
     {
         GICv5SPIState *spi = spi_for_selr(cs, domain);
         if (spi) {
+            GICv5TriggerMode old_tm = spi->tm;
             spi->tm = FIELD_EX32(data, IRS_SPI_CFGR, TM);
+            if (spi->tm != old_tm) {
+                /*
+                 * R_KBPXL: updates to SPI trigger mode can generate CLEAR or
+                 * SET_LEVEL events. This is not the same logic as spi_sample().
+                 */
+                if (spi->tm == GICV5_TRIGGER_LEVEL) {
+                    if (spi->level) {
+                        spi->pending = true;
+                        spi->hm = GICV5_LEVEL;
+                    } else {
+                        spi->pending = false;
+                    }
+                } else if (spi->level) {
+                    spi->pending = false;
+                }
+            }
         }
         return true;
     }
@@ -1109,6 +1148,17 @@ static bool config_writel(GICv5 *s, GICv5Domain domain, hwaddr offset,
             }
         }
         return true;
+    case A_IRS_SPI_RESAMPLER:
+    {
+        uint32_t id = FIELD_EX32(data, IRS_SPI_RESAMPLER, SPI_ID);
+        GICv5SPIState *spi = gicv5_spi_state(cs, id, domain);
+
+        if (spi) {
+            spi_sample(spi);
+        }
+        trace_gicv5_spi_state(id, spi->level, spi->pending, spi->active);
+        return true;
+    }
     }
 
     return false;
@@ -1259,8 +1309,17 @@ static void gicv5_set_spi(void *opaque, int irq, int level)
     /* These irqs are all SPIs; the INTID is irq + s->spi_base */
     GICv5Common *cs = ARM_GICV5_COMMON(opaque);
     uint32_t spi_id = irq + cs->spi_base;
+    GICv5SPIState *spi = gicv5_raw_spi_state(cs, spi_id);
+
+    if (!spi || spi->level == level) {
+        return;
+    }
 
     trace_gicv5_spi(spi_id, level);
+
+    spi->level = level;
+    spi_sample(spi);
+    trace_gicv5_spi_state(spi_id, spi->level, spi->pending, spi->active);
 }
 
 static void gicv5_reset_hold(Object *obj, ResetType type)
diff --git a/hw/intc/trace-events b/hw/intc/trace-events
index 409935e15a..4c55af2780 100644
--- a/hw/intc/trace-events
+++ b/hw/intc/trace-events
@@ -241,6 +241,7 @@ gicv5_set_pending(const char *domain, const char *type, bool virtual, uint32_t i
 gicv5_set_handling(const char *domain, const char *type, bool virtual, uint32_t id, int handling) "GICv5 IRS SetHandling %s %s virtual:%d ID %u handling %d"
 gicv5_set_target(const char *domain, const char *type, bool virtual, uint32_t id, uint32_t iaffid, int irm) "GICv5 IRS SetTarget %s %s virtual:%d ID %u IAFFID %u routingmode %d"
 gicv5_request_config(const char *domain, const char *type, bool virtual, uint32_t id, uint64_t icsr) "GICv5 IRS RequestConfig %s %s virtual:%d ID %u ICSR 0x%" PRIx64
+gicv5_spi_state(uint32_t spi_id, bool level, bool pending, bool active) "GICv5 IRS SPI ID %u now level %d pending %d active %d"
 
 # arm_gicv5_common.c
 gicv5_common_realize(uint32_t irsid, uint32_t num_cpus, uint32_t spi_base, uint32_t spi_irs_range, uint32_t spi_range) "GICv5 IRS realized: IRS ID %u, %u CPUs, SPI base %u, SPI IRS range %u, SPI range %u"
-- 
2.43.0