[PATCH v5 02/10] hw/fsi: Introduce IBM's scratchpad

[Ninad Palsule]

This is a part of patchset where scratchpad is introduced.

The scratchpad provides a set of non-functional registers. The firmware
is free to use them, hardware does not support any special management
support. The scratchpad registers can be read or written from LBUS
slave.

In this model, The LBUS device is parent for the scratchpad.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
---
v2:
- Incorporated Joel's review comments.
v5:
- Incorporated review comments by Cedric.
---
 include/hw/fsi/engine-scratchpad.h | 33 ++++++++++
 hw/fsi/engine-scratchpad.c         | 99 ++++++++++++++++++++++++++++++
 hw/fsi/Kconfig                     |  4 ++
 hw/fsi/meson.build                 |  1 +
 hw/fsi/trace-events                |  2 +
 5 files changed, 139 insertions(+)
 create mode 100644 include/hw/fsi/engine-scratchpad.h
 create mode 100644 hw/fsi/engine-scratchpad.c
 create mode 100644 hw/fsi/trace-events

diff --git a/include/hw/fsi/engine-scratchpad.h 
b/include/hw/fsi/engine-scratchpad.h
new file mode 100644
index 0000000000..17e9570c5c
--- /dev/null
+++ b/include/hw/fsi/engine-scratchpad.h
@@ -0,0 +1,33 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (C) 2023 IBM Corp.
+ *
+ * IBM scratchpad engne
+ */
+#ifndef FSI_ENGINE_SCRATCHPAD_H
+#define FSI_ENGINE_SCRATCHPAD_H
+
+#include "qemu/bitops.h"
+
+#include "hw/fsi/lbus.h"
+
+#define ENGINE_CONFIG_NEXT              BE_BIT(0)
+#define ENGINE_CONFIG_VPD               BE_BIT(1)
+#define ENGINE_CONFIG_SLOTS             BE_GENMASK(8, 15)
+#define ENGINE_CONFIG_VERSION           BE_GENMASK(16, 19)
+#define ENGINE_CONFIG_TYPE              BE_GENMASK(20, 27)
+#define   ENGINE_CONFIG_TYPE_PEEK       (0x02 << 4)
+#define   ENGINE_CONFIG_TYPE_FSI        (0x03 << 4)
+#define   ENGINE_CONFIG_TYPE_SCRATCHPAD (0x06 << 4)
+#define ENGINE_CONFIG_CRC              BE_GENMASK(28, 31)
+
+#define TYPE_SCRATCHPAD "scratchpad"
+#define SCRATCHPAD(obj) OBJECT_CHECK(ScratchPad, (obj), TYPE_SCRATCHPAD)
+
+typedef struct ScratchPad {
+        FSILBusDevice parent;
+
+        uint32_t reg;
+} ScratchPad;
+
+#endif /* FSI_ENGINE_SCRATCHPAD_H */
diff --git a/hw/fsi/engine-scratchpad.c b/hw/fsi/engine-scratchpad.c
new file mode 100644
index 0000000000..60f678eec4
--- /dev/null
+++ b/hw/fsi/engine-scratchpad.c
@@ -0,0 +1,99 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (C) 2023 IBM Corp.
+ *
+ * IBM scratchpad engine
+ */
+
+#include "qemu/osdep.h"
+
+#include "qapi/error.h"
+#include "qemu/log.h"
+#include "trace.h"
+
+#include "hw/fsi/engine-scratchpad.h"
+
+static uint64_t scratchpad_read(void *opaque, hwaddr addr, unsigned size)
+{
+    ScratchPad *s = SCRATCHPAD(opaque);
+
+    trace_scratchpad_read(addr, size);
+
+    if (addr) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out of bounds read: 0x%"HWADDR_PRIx" for %u\n",
+                      __func__, addr, size);
+        return 0;
+    }
+
+    return s->reg;
+}
+
+static void scratchpad_write(void *opaque, hwaddr addr, uint64_t data,
+                                 unsigned size)
+{
+    ScratchPad *s = SCRATCHPAD(opaque);
+
+    trace_scratchpad_write(addr, size, data);
+
+    if (addr) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out of bounds write: 0x%"HWADDR_PRIx" for %u\n",
+                      __func__, addr, size);
+        return;
+    }
+
+    s->reg = data;
+}
+
+static const struct MemoryRegionOps scratchpad_ops = {
+    .read = scratchpad_read,
+    .write = scratchpad_write,
+    .endianness = DEVICE_BIG_ENDIAN,
+};
+
+static void scratchpad_realize(DeviceState *dev, Error **errp)
+{
+    FSILBusDevice *ldev = FSI_LBUS_DEVICE(dev);
+
+    memory_region_init_io(&ldev->iomem, OBJECT(ldev), &scratchpad_ops,
+                          ldev, TYPE_SCRATCHPAD, 0x400);
+}
+
+static void scratchpad_reset(DeviceState *dev)
+{
+    ScratchPad *s = SCRATCHPAD(dev);
+
+    s->reg = 0;
+}
+
+static void scratchpad_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    FSILBusDeviceClass *ldc = FSI_LBUS_DEVICE_CLASS(klass);
+
+    dc->realize = scratchpad_realize;
+    dc->reset = scratchpad_reset;
+
+    ldc->config =
+          ENGINE_CONFIG_NEXT            /* valid */
+        | 0x00010000                    /* slots */
+        | 0x00001000                    /* version */
+        | ENGINE_CONFIG_TYPE_SCRATCHPAD /* type */
+        | 0x00000007;                   /* crc */
+}
+
+static const TypeInfo scratchpad_info = {
+    .name = TYPE_SCRATCHPAD,
+    .parent = TYPE_FSI_LBUS_DEVICE,
+    .instance_size = sizeof(ScratchPad),
+    .class_init = scratchpad_class_init,
+    .class_size = sizeof(FSILBusDeviceClass),
+};
+
+static void scratchpad_register_types(void)
+{
+    type_register_static(&scratchpad_info);
+}
+
+type_init(scratchpad_register_types);
diff --git a/hw/fsi/Kconfig b/hw/fsi/Kconfig
index e650c660f0..f7c7fd1b28 100644
--- a/hw/fsi/Kconfig
+++ b/hw/fsi/Kconfig
@@ -1,2 +1,6 @@
+config FSI_SCRATCHPAD
+    bool
+    select FSI_LBUS
+
 config FSI_LBUS
     bool
diff --git a/hw/fsi/meson.build b/hw/fsi/meson.build
index 4074d3a7d2..d45a98c223 100644
--- a/hw/fsi/meson.build
+++ b/hw/fsi/meson.build
@@ -1 +1,2 @@
 system_ss.add(when: 'CONFIG_FSI_LBUS', if_true: files('lbus.c'))
+system_ss.add(when: 'CONFIG_FSI_SCRATCHPAD', if_true: 
files('engine-scratchpad.c'))
diff --git a/hw/fsi/trace-events b/hw/fsi/trace-events
new file mode 100644
index 0000000000..97fd070354
--- /dev/null
+++ b/hw/fsi/trace-events
@@ -0,0 +1,2 @@
+scratchpad_read(uint64_t addr, uint32_t size) "@0x%" PRIx64 " size=%d"
+scratchpad_write(uint64_t addr, uint32_t size, uint64_t data) "@0x%" PRIx64 " 
size=%d value=0x%"PRIx64
-- 
2.39.2