[RFC PATCH] RFC: Sketch of dm event notification

Simon Glass
2021-11-01T03:07:16Z

This is a patch for Takahiro to look at, just for illustration. Not ready
for review.

To run the test:

./u-boot -T -c "ut common test_event_probe"

Signed-off-by: Simon Glass <sjg@chromium.org>
---

common/Kconfig | 11 ++++
common/Makefile | 2 +
common/board_f.c | 2 +
common/event.c | 103 ++++++++++++++++++++++++++++++
common/log.c | 1 +
drivers/core/device.c | 14 ++++
include/asm-generic/global_data.h | 3 +
include/event.h | 103 ++++++++++++++++++++++++++++++
include/event_internal.h | 34 ++++++++++
include/log.h | 2 +
test/common/Makefile | 1 +
test/common/event.c | 85 ++++++++++++++++++++++++
test/test-main.c | 5 ++
13 files changed, 366 insertions(+)
create mode 100644 common/event.c
create mode 100644 include/event.h
create mode 100644 include/event_internal.h
create mode 100644 test/common/event.c

diff --git a/common/Kconfig b/common/Kconfig
index d6f77ab7b9c..54d0adaa8d5 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -484,6 +484,17 @@ config DISPLAY_BOARDINFO_LATE

menu "Start-up hooks"

+config EVENT
+ bool "General-purpose event-handling mechanism"
+ default y if SANDBOX
+ help
+ This enables sending and processing of events, to allow interested
+ parties to be alerted when something happens. This is an attempt to
+ step the flow of weak functions, hooks, functions in board_f.c
+ and board_r.c and the Kconfig options below.
+
+ See doc/develop/event.rst for more information.
+
config ARCH_EARLY_INIT_R
bool "Call arch-specific init soon after relocation"
help
diff --git a/common/Makefile b/common/Makefile
index e7839027b6c..1b4601ac13f 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -101,6 +101,8 @@ obj-y += malloc_simple.o
endif
endif

+obj-$(CONFIG_EVENT) += event.o
+
obj-y += image.o image-board.o
obj-$(CONFIG_$(SPL_TPL_)HASH) += hash.o
obj-$(CONFIG_ANDROID_AB) += android_ab.o
diff --git a/common/board_f.c b/common/board_f.c
index 3dc0eaa59c5..faf262d564c 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -19,6 +19,7 @@
#include <dm.h>
#include <env.h>
#include <env_internal.h>
+#include <event.h>
#include <fdtdec.h>
#include <fs.h>
#include <hang.h>
@@ -820,6 +821,7 @@ static const init_fnc_t init_sequence_f[] = {
initf_malloc,
log_init,
initf_bootstage, /* uses its own timer, so does not need DM */
+ event_init,
#ifdef CONFIG_BLOBLIST
bloblist_init,
#endif
diff --git a/common/event.c b/common/event.c
new file mode 100644
index 00000000000..428628da44d
--- /dev/null
+++ b/common/event.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Events provide a general-purpose way to react to / subscribe to changes
+ * within U-Boot
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY LOGC_EVENT
+
+#include <common.h>
+#include <event.h>
+#include <event_internal.h>
+#include <log.h>
+#include <malloc.h>
+#include <asm/global_data.h>
+#include <linux/list.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static void spy_free(struct event_spy *spy)
+{
+ list_del(&spy->sibling_node);
+}
+
+int event_register(const char *id, enum event_t type, event_handler_t func, void *ctx)
+{
+ struct event_state *state = gd->event_state;
+ struct event_spy *spy;
+
+ spy = malloc(sizeof(*spy));
+ if (!spy)
+ return log_msg_ret("alloc", -ENOMEM);
+
+ spy->id = id;
+ spy->type = type;
+ spy->func = func;
+ spy->ctx = ctx;
+ list_add_tail(&spy->sibling_node, &state->spy_head);
+
+ return 0;
+}
+
+int event_notify(enum event_t type, void *data, int size)
+{
+ struct event_state *state = gd->event_state;
+ struct event_spy *spy, *next;
+ struct event event;
+
+ event.type = type;
+ if (size > sizeof(event.data))
+ return log_msg_ret("size", -E2BIG);
+ memcpy(&event.data, data, size);
+ list_for_each_entry_safe(spy, next, &state->spy_head, sibling_node) {
+ if (spy->type == type) {
+ int ret;
+
+ log_debug("Sending event %x to spy '%s'\n", type,
+ spy->id);
+ ret = spy->func(spy->ctx, &event);
+
+ /*
+ * TODO: Handle various return codes to
+ *
+ * - claim an event (no others will see it)
+ * - return an error from the event
+ */
+ if (ret)
+ return log_msg_ret("spy", ret);
+ }
+ }
+
+ return 0;
+}
+
+int event_uninit(void)
+{
+ struct event_state *state = gd->event_state;
+ struct event_spy *spy, *next;
+
+ if (!state)
+ return 0;
+ list_for_each_entry_safe(spy, next, &state->spy_head, sibling_node)
+ spy_free(spy);
+
+ return 0;
+}
+
+int event_init(void)
+{
+ struct event_state *state;
+
+ state = malloc(sizeof(struct event_state));
+ if (!state)
+ return log_msg_ret("alloc", -ENOMEM);
+
+ INIT_LIST_HEAD(&state->spy_head);
+
+ gd->event_state = state;
+
+ return 0;
+}
diff --git a/common/log.c b/common/log.c
index 1aaa6c1527b..aa2e780d2d7 100644
--- a/common/log.c
+++ b/common/log.c
@@ -28,6 +28,7 @@ static const char *const log_cat_name[] = {
"devres",
"acpi",
"boot",
+ "event",
};

_Static_assert(ARRAY_SIZE(log_cat_name) == LOGC_COUNT - LOGC_NONE,
diff --git a/drivers/core/device.c b/drivers/core/device.c
index efd07176e37..c52b47d5cc1 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -10,6 +10,7 @@

#include <common.h>
#include <cpu_func.h>
+#include <event.h>
#include <log.h>
#include <asm/global_data.h>
#include <asm/io.h>
@@ -482,6 +483,11 @@ static int device_get_dma_constraints(struct udevice *dev)
return 0;
}

+static int device_notify(const struct udevice *dev, enum event_t type)
+{
+ return event_notify(type, &dev, sizeof(dev));
+}
+
int device_probe(struct udevice *dev)
{
const struct driver *drv;
@@ -493,6 +499,10 @@ int device_probe(struct udevice *dev)
if (dev_get_flags(dev) & DM_FLAG_ACTIVATED)
return 0;

+ ret = device_notify(dev, EVT_DM_PRE_PROBE);
+ if (ret)
+ return ret;
+
drv = dev->driver;
assert(drv);

@@ -589,6 +599,10 @@ int device_probe(struct udevice *dev)
if (dev->parent && device_get_uclass_id(dev) == UCLASS_PINCTRL)
pinctrl_select_state(dev, "default");

+ ret = device_notify(dev, EVT_DM_POST_PROBE);
+ if (ret)
+ return ret;
+
return 0;
fail_uclass:
if (device_remove(dev, DM_REMOVE_NORMAL)) {
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index 16fd305a65c..771cda57a58 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -459,6 +459,9 @@ struct global_data {
*/
char *smbios_version;
#endif
+#if CONFIG_IS_ENABLED(EVENT)
+ struct event_state *event_state;
+#endif
};
#ifndef DO_DEPS_ONLY
static_assert(sizeof(struct global_data) == GD_SIZE);
diff --git a/include/event.h b/include/event.h
new file mode 100644
index 00000000000..d44fd53639a
--- /dev/null
+++ b/include/event.h
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Events provide a general-purpose way to react to / subscribe to changes
+ * within U-Boot
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __event_h
+#define __event_h
+
+/**
+ * enum event_t - Types of events supported by U-Boot
+ *
+ * @EVT_DM_PRE_PROBE: Device is about to be probed
+ */
+enum event_t {
+ EVT_NONE,
+ EVT_TEST,
+
+ /* Events related to driver model */
+ EVT_DM_PRE_PROBE,
+ EVT_DM_POST_PROBE,
+
+ EVT_COUNT
+};
+
+union event_data {
+ /**
+ * struct event_data_test - test data
+ *
+ * @signal: A value to update the state with
+ */
+ struct event_data_test {
+ int signal;
+ } test;
+
+ /**
+ * struct event_dm - driver model event
+ *
+ * @dev: Device this event relates to
+ */
+ struct event_dm {
+ struct udevice *dev;
+ } dm;
+};
+
+/**
+ * struct event - an event that can be sent and received
+ *
+ * @type: Event type
+ * @data: Data for this particular event
+ */
+struct event {
+ enum event_t type;
+ union event_data data;
+};
+
+/** Function type for event handlers */
+typedef int (*event_handler_t)(void *ctx, struct event *event);
+
+/**
+ * event_register - register a new spy
+ *
+ * @id: Spy ID
+ * @type: Event type to subscribe to
+ * @func: Function to call when the event is sent
+ * @ctx: Context to pass to the function
+ * @return 0 if OK, -ve on erropr
+ */
+int event_register(const char *id, enum event_t type, event_handler_t func,
+ void *ctx);
+
+/**
+ * event_notify() - notify spies about an event
+ *
+ * It is possible to pass in union event_data here but that may not be
+ * convenient if the data is elsewhere, or is one of the members of the union.
+ * So this uses a void * for @data, with a separate @size.
+ *
+ * @type: Event type
+ * @data: Event data to be sent (e.g. union_event_data)
+ * @size: Size of data in bytes
+ */
+int event_notify(enum event_t type, void *data, int size);
+
+#if CONFIG_IS_ENABLED(EVENT)
+int event_uninit(void);
+int event_init(void);
+#else
+static int event_uninit(void)
+{
+ return 0;
+}
+
+static inline int event_init(void)
+{
+ return 0;
+}
+#endif
+
+#endif
diff --git a/include/event_internal.h b/include/event_internal.h
new file mode 100644
index 00000000000..19308453f7b
--- /dev/null
+++ b/include/event_internal.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Internal definitions for events
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __event_internal_h
+#define __event_internal_h
+
+#include <linux/list.h>
+
+/**
+ * struct event_spy - a spy that watches for an event of a particular type
+ *
+ * @id: Spy ID
+ * @type: Event type to subscribe to
+ * @func: Function to call when the event is sent
+ * @ctx: Context to pass to the function
+ */
+struct event_spy {
+ struct list_head sibling_node;
+ const char *id;
+ enum event_t type;
+ event_handler_t func;
+ void *ctx;
+};
+
+struct event_state {
+ struct list_head spy_head;
+};
+
+#endif
diff --git a/include/log.h b/include/log.h
index e0e12ce1944..7169fff7aa5 100644
--- a/include/log.h
+++ b/include/log.h
@@ -98,6 +98,8 @@ enum log_category_t {
LOGC_ACPI,
/** @LOGC_BOOT: Related to boot process / boot image processing */
LOGC_BOOT,
+ /** @LOGC_EVENT: Related to event and event handling */
+ LOGC_EVENT,
/** @LOGC_COUNT: Number of log categories */
LOGC_COUNT,
/** @LOGC_END: Sentinel value for lists of log categories */
diff --git a/test/common/Makefile b/test/common/Makefile
index 24c9145dccc..9087788ba6a 100644
--- a/test/common/Makefile
+++ b/test/common/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0+
obj-y += cmd_ut_common.o
obj-$(CONFIG_AUTOBOOT) += test_autoboot.o
+obj-$(CONFIG_EVENT) += event.o
diff --git a/test/common/event.c b/test/common/event.c
new file mode 100644
index 00000000000..6f359e2a933
--- /dev/null
+++ b/test/common/event.c
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Unit tests for event handling
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <event.h>
+#include <test/common.h>
+#include <test/test.h>
+#include <test/ut.h>
+
+struct test_state {
+ struct udevice *dev;
+ int val;
+};
+
+static int h_adder(void *ctx, struct event *event)
+{
+ struct event_data_test *data = &event->data.test;
+ struct test_state *test_state = ctx;
+
+ test_state->val += data->signal;
+
+ return 0;
+}
+
+static int test_event_base(struct unit_test_state *uts)
+{
+ struct test_state state;
+ int signal;
+
+ state.val = 12;
+ ut_assertok(event_register("wibble", EVT_TEST, h_adder, &state));
+
+ signal = 17;
+
+ /* Check that the handler is called */
+ ut_assertok(event_notify(EVT_TEST, &signal, sizeof(signal)));
+ ut_asserteq(12 + 17, state.val);
+
+ return 0;
+}
+COMMON_TEST(test_event_base, 0);
+
+static int h_probe(void *ctx, struct event *event)
+{
+ struct test_state *test_state = ctx;
+
+ test_state->dev = event->data.dm.dev;
+ switch (event->type) {
+ case EVT_DM_PRE_PROBE:
+ test_state->val |= 1;
+ break;
+ case EVT_DM_POST_PROBE:
+ test_state->val |= 2;
+ break;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static int test_event_probe(struct unit_test_state *uts)
+{
+ struct test_state state;
+ struct udevice *dev;
+
+ state.val = 0;
+ ut_assertok(event_register("pre", EVT_DM_PRE_PROBE, h_probe, &state));
+ ut_assertok(event_register("post", EVT_DM_POST_PROBE, h_probe, &state));
+
+ /* Probe a device */
+ ut_assertok(uclass_first_device_err(UCLASS_TEST_FDT, &dev));
+
+ /* Check that the handler is called */
+ ut_asserteq(3, state.val);
+
+ return 0;
+}
+COMMON_TEST(test_event_probe, UT_TESTF_DM | UT_TESTF_SCAN_FDT);
diff --git a/test/test-main.c b/test/test-main.c
index 3cdf6849c57..c3ccdf3fed8 100644
--- a/test/test-main.c
+++ b/test/test-main.c
@@ -7,6 +7,7 @@
#include <common.h>
#include <console.h>
#include <dm.h>
+#include <event.h>
#include <dm/root.h>
#include <dm/test.h>
#include <dm/uclass-internal.h>
@@ -218,6 +219,9 @@ static int dm_test_restore(struct device_node *of_root)
*/
static int test_pre_run(struct unit_test_state *uts, struct unit_test *test)
{
+ gd->event_state = NULL;
+ ut_assertok(event_init());
+
if (test->flags & UT_TESTF_DM)
ut_assertok(dm_test_pre_run(uts));

@@ -260,6 +264,7 @@ static int test_post_run(struct unit_test_state *uts, struct unit_test *test)
ut_unsilence_console(uts);
if (test->flags & UT_TESTF_DM)
ut_assertok(dm_test_post_run(uts));
+ ut_assertok(event_uninit());

return 0;
}
--
2.33.1.1089.g2158813163f-goog