[ot] hw/opentitan: ot_spi_device: Add Passthrough IRQs and SPI Host prop

This adds the corresponding out IRQs to OT SPI Device, as well as a
property that contains the downstream OT SPI Host.

Signed-off-by: Alice Ziuziakowska <[email protected]>

Author: ziuziakowska

hw/opentitan/Kconfig

@@ -196,6 +196,7 @@ config OT_SOCDBG_CTRL
 
 config OT_SPI_DEVICE
     bool
+    select OT_SPI_HOST
 
 config OT_SPI_HOST
     bool

hw/opentitan/ot_spi_device.c

@@ -36,6 +36,7 @@
 #include "hw/opentitan/ot_common.h"
 #include "hw/opentitan/ot_fifo32.h"
 #include "hw/opentitan/ot_spi_device.h"
+#include "hw/opentitan/ot_spi_host.h"
 #include "hw/qdev-properties-system.h"
 #include "hw/qdev-properties.h"
 #include "hw/registerfields.h"
@@ -450,12 +451,17 @@ struct OtSPIDeviceState {
     SpiDeviceFlash flash;
     SpiDeviceTpm tpm;
 
+    /* CS signal for downstream flash in passthrough mode, active low */
+    IbexIRQ passthrough_cs;
+    IbexIRQ passthrough_en;
+
     uint32_t *spi_regs; /* Registers */
     uint32_t *tpm_regs; /* Registers */
     uint32_t *sram;
 
     /* Properties */
     char *ot_id;
+    OtSPIHostState *spihost; /* downstream SPI Host */
     CharBackend chr; /* communication device */
     guint watch_tag; /* tracker for comm device change */
 };
@@ -2311,6 +2317,8 @@ static int ot_spi_device_chr_be_change(void *opaque)
 static Property ot_spi_device_properties[] = {
     DEFINE_PROP_STRING(OT_COMMON_DEV_ID, OtSPIDeviceState, ot_id),
     DEFINE_PROP_CHR("chardev", OtSPIDeviceState, chr),
+    DEFINE_PROP_LINK("spihost", OtSPIDeviceState, spihost, TYPE_OT_SPI_HOST,
+                     OtSPIHostState *),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -2373,6 +2381,9 @@ static void ot_spi_device_reset_enter(Object *obj, ResetType type)
 
     s->tpm_regs[R_TPM_CAP] = 0x660100u;
 
+    ibex_irq_lower(&s->passthrough_en);
+    ibex_irq_raise(&s->passthrough_cs);
+
     ot_spi_device_update_irqs(s);
     ot_spi_device_update_alerts(s);
 }
@@ -2430,6 +2441,12 @@ static void ot_spi_device_init(Object *obj)
         ibex_qdev_init_irq(obj, &s->alerts[ix], OT_DEVICE_ALERT);
     }
 
+    /* Passthrough enable is active high, CS is active low */
+    ibex_qdev_init_irq_default(OBJECT(s), &s->passthrough_en,
+                               OT_SPI_DEVICE_PASSTHROUGH_EN, 0);
+    ibex_qdev_init_irq_default(OBJECT(s), &s->passthrough_cs,
+                               OT_SPI_DEVICE_PASSTHROUGH_CS, 1);
+
     /*
      * This timer is used to hand over to the vCPU whenever a READBUF_* irq is
      * raised, otherwide the vCPU would not be able to get notified that a

include/hw/opentitan/ot_spi_device.h

@@ -2,9 +2,11 @@
  * QEMU OpenTitan SPI Device controller
  *
  * Copyright (c) 2023-2025 Rivos, Inc.
+ * Copyright (c) 2025 lowRISC contributors.
  *
  * Author(s):
  *  Emmanuel Blot <[email protected]>
+ *  Alice Ziuziakowska <[email protected]>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -33,4 +35,8 @@
 #define TYPE_OT_SPI_DEVICE "ot-spi_device"
 OBJECT_DECLARE_TYPE(OtSPIDeviceState, OtSPIDeviceClass, OT_SPI_DEVICE)
 
+/* IRQ lines to downstream OT SPI Host */
+#define OT_SPI_DEVICE_PASSTHROUGH_EN (TYPE_OT_SPI_DEVICE "-passthrough-en")
+#define OT_SPI_DEVICE_PASSTHROUGH_CS (TYPE_OT_SPI_DEVICE "-passthrough-cs")
+
 #endif /* HW_OPENTITAN_OT_SPI_DEVICE_H */