Add a simple SPI peripheral that echoes back received data. Useful for
testing SPI controllers.

Signed-off-by: Octavian Purdila <tavip@google.com>
---
 include/hw/misc/spi_tester.h | 32 +++++++++++++++++
 hw/misc/spi_tester.c         | 67 ++++++++++++++++++++++++++++++++++++
 hw/misc/Kconfig              |  5 +++
 hw/misc/meson.build          |  1 +
 4 files changed, 105 insertions(+)
 create mode 100644 include/hw/misc/spi_tester.h
 create mode 100644 hw/misc/spi_tester.c

diff --git a/include/hw/misc/spi_tester.h b/include/hw/misc/spi_tester.h
new file mode 100644
index 0000000000..8935f3f1af
--- /dev/null
+++ b/include/hw/misc/spi_tester.h
@@ -0,0 +1,32 @@
+/*
+ * Simple SPI peripheral device used for SPI controller testing.
+ *
+ * Copyright (c) 2024 Google LLC.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef HW_SPI_TESTER_H
+#define HW_SPI_TESTER_H
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/bswap.h"
+#include "hw/irq.h"
+#include "hw/ssi/ssi.h"
+#include "qemu/timer.h"
+#include "hw/qdev-properties.h"
+
+#define TYPE_SPI_TESTER "spi-tester"
+#define SPI_TESTER(obj) OBJECT_CHECK(SpiTesterState, (obj), TYPE_SPI_TESTER)
+
+typedef struct {
+    SSIPeripheral ssidev;
+    bool cs;
+} SpiTesterState;
+
+#endif /* HW_SPI_TESTER_H */
diff --git a/hw/misc/spi_tester.c b/hw/misc/spi_tester.c
new file mode 100644
index 0000000000..2793ce52dc
--- /dev/null
+++ b/hw/misc/spi_tester.c
@@ -0,0 +1,67 @@
+/*
+ * Simple SPI peripheral echo device used for SPI controller testing.
+ *
+ * Copyright (c) 2024 Google LLC.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "migration/vmstate.h"
+#include "hw/misc/spi_tester.h"
+
+static uint32_t spi_tester_transfer(SSIPeripheral *dev, uint32_t value)
+{
+    SpiTesterState *s = SPI_TESTER(dev);
+
+    if (s->cs) {
+        return 0;
+    }
+
+    return value;
+}
+
+static int spi_tester_set_cs(SSIPeripheral *dev, bool select)
+{
+    SpiTesterState *s = SPI_TESTER(dev);
+
+    s->cs = select;
+
+    return 0;
+}
+
+static const VMStateDescription vmstate_spi_tester = {
+    .name = "spi-tester",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_SSI_PERIPHERAL(ssidev, SpiTesterState),
+        VMSTATE_BOOL(cs, SpiTesterState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void spi_tester_class_init(ObjectClass *klass, void *data)
+{
+    SSIPeripheralClass *k = SSI_PERIPHERAL_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &vmstate_spi_tester;
+    k->transfer    = spi_tester_transfer;
+    k->set_cs      = spi_tester_set_cs;
+    k->cs_polarity = SSI_CS_LOW;
+}
+
+static const TypeInfo spi_tester_types[] = {
+    {
+        .name          = TYPE_SPI_TESTER,
+        .parent        = TYPE_SSI_PERIPHERAL,
+        .instance_size = sizeof(SpiTesterState),
+        .class_init    = spi_tester_class_init,
+    },
+};
+
+DEFINE_TYPES(spi_tester_types);
diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
index 3e93c12c8e..484ee3149f 100644
--- a/hw/misc/Kconfig
+++ b/hw/misc/Kconfig
@@ -218,6 +218,11 @@ config I2C_TESTER
     default y if TEST_DEVICES
     depends on I2C
 
+config SPI_TESTER
+    bool
+    default y if TEST_DEVICES
+    depends on SSI
+
 config FLEXCOMM
     bool
     select I2C
diff --git a/hw/misc/meson.build b/hw/misc/meson.build
index 4f22231fa3..413171f379 100644
--- a/hw/misc/meson.build
+++ b/hw/misc/meson.build
@@ -159,6 +159,7 @@ system_ss.add(when: 'CONFIG_SBSA_REF', if_true: files('sbsa_ec.c'))
 system_ss.add(when: 'CONFIG_LASI', if_true: files('lasi.c'))
 
 system_ss.add(when: 'CONFIG_I2C_TESTER', if_true: files('i2c_tester.c'))
+system_ss.add(when: 'CONFIG_SPI_TESTER', if_true: files('spi_tester.c'))
 
 system_ss.add(when: 'CONFIG_FLEXCOMM', if_true: files('flexcomm.c'))
 system_ss.add(when: 'CONFIG_RT500_CLKCTL', if_true: files('rt500_clkctl0.c', 'rt500_clkctl1.c'))
-- 
2.46.0.662.g92d0881bb0-goog