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Message-ID: <20250221133501.2203897-2-koichiro.den@canonical.com>
Date: Fri, 21 Feb 2025 22:34:59 +0900
From: Koichiro Den <koichiro.den@...onical.com>
To: linux-gpio@...r.kernel.org
Cc: brgl@...ev.pl,
geert+renesas@...der.be,
linus.walleij@...aro.org,
maciej.borzecki@...onical.com,
linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/3] gpio: introduce utilities for synchronous fake device creation
Both gpio-sim and gpio-virtuser share a mechanism to instantiate a
platform device, wait for probe completion, and retrieve the probe
success or error status synchronously. With gpio-aggregator planned to
adopt this approach for its configfs interface, it's time to factor
out the common code.
Add dev-sync-probe.[ch] to house helper functions used by all such
implementations.
No functional change.
Signed-off-by: Koichiro Den <koichiro.den@...onical.com>
---
drivers/gpio/Kconfig | 3 ++
drivers/gpio/Makefile | 3 ++
drivers/gpio/dev-sync-probe.c | 97 +++++++++++++++++++++++++++++++++++
drivers/gpio/dev-sync-probe.h | 25 +++++++++
4 files changed, 128 insertions(+)
create mode 100644 drivers/gpio/dev-sync-probe.c
create mode 100644 drivers/gpio/dev-sync-probe.h
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 56c1f30ac195..e15405add317 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1947,3 +1947,6 @@ config GPIO_VIRTUSER
endmenu
endif
+
+config DEV_SYNC_PROBE
+ tristate
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index af3ba4d81b58..af130882ffee 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -19,6 +19,9 @@ obj-$(CONFIG_GPIO_GENERIC) += gpio-generic.o
# directly supported by gpio-generic
gpio-generic-$(CONFIG_GPIO_GENERIC) += gpio-mmio.o
+# Utilities for drivers that need synchronous fake device creation
+obj-$(CONFIG_DEV_SYNC_PROBE) += dev-sync-probe.o
+
obj-$(CONFIG_GPIO_104_DIO_48E) += gpio-104-dio-48e.o
obj-$(CONFIG_GPIO_104_IDI_48) += gpio-104-idi-48.o
obj-$(CONFIG_GPIO_104_IDIO_16) += gpio-104-idio-16.o
diff --git a/drivers/gpio/dev-sync-probe.c b/drivers/gpio/dev-sync-probe.c
new file mode 100644
index 000000000000..9ea733b863b2
--- /dev/null
+++ b/drivers/gpio/dev-sync-probe.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Common code for drivers creating fake platform devices.
+ *
+ * Provides synchronous device creation: waits for probe completion and
+ * returns the probe success or error status to the device creator.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@...ev.pl>
+ * Copyright (C) 2025 Koichiro Den <koichiro.den@...onical.com>
+ */
+
+#include <linux/device.h>
+#include <linux/slab.h>
+
+#include "dev-sync-probe.h"
+
+static int dev_sync_probe_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct dev_sync_probe_data *pdata;
+ struct device *dev = data;
+
+ pdata = container_of(nb, struct dev_sync_probe_data, bus_notifier);
+ if (!device_match_name(dev, pdata->name))
+ return NOTIFY_DONE;
+
+ switch (action) {
+ case BUS_NOTIFY_BOUND_DRIVER:
+ pdata->driver_bound = true;
+ break;
+ case BUS_NOTIFY_DRIVER_NOT_BOUND:
+ pdata->driver_bound = false;
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ complete(&pdata->probe_completion);
+ return NOTIFY_OK;
+}
+
+void dev_sync_probe_init(struct dev_sync_probe_data *data)
+{
+ memset(data, 0, sizeof(*data));
+ init_completion(&data->probe_completion);
+ data->bus_notifier.notifier_call = dev_sync_probe_notifier_call;
+}
+EXPORT_SYMBOL_GPL(dev_sync_probe_init);
+
+int dev_sync_probe_register(struct dev_sync_probe_data *data,
+ struct platform_device_info *pdevinfo)
+{
+ struct platform_device *pdev;
+ char *name;
+
+ name = kasprintf(GFP_KERNEL, "%s.%d", pdevinfo->name, pdevinfo->id);
+ if (!name)
+ return -ENOMEM;
+
+ data->driver_bound = false;
+ data->name = name;
+ reinit_completion(&data->probe_completion);
+ bus_register_notifier(&platform_bus_type, &data->bus_notifier);
+
+ pdev = platform_device_register_full(pdevinfo);
+ if (IS_ERR(pdev)) {
+ bus_unregister_notifier(&platform_bus_type, &data->bus_notifier);
+ kfree(data->name);
+ return PTR_ERR(pdev);
+ }
+
+ wait_for_completion(&data->probe_completion);
+ bus_unregister_notifier(&platform_bus_type, &data->bus_notifier);
+
+ if (!data->driver_bound) {
+ platform_device_unregister(pdev);
+ kfree(data->name);
+ return -ENXIO;
+ }
+
+ data->pdev = pdev;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dev_sync_probe_register);
+
+void dev_sync_probe_unregister(struct dev_sync_probe_data *data)
+{
+ platform_device_unregister(data->pdev);
+ kfree(data->name);
+ data->pdev = NULL;
+}
+EXPORT_SYMBOL_GPL(dev_sync_probe_unregister);
+
+MODULE_AUTHOR("Bartosz Golaszewski <brgl@...ev.pl>");
+MODULE_AUTHOR("Koichiro Den <koichiro.den@...onical.com>");
+MODULE_DESCRIPTION("Utilities for synchronous fake device creation");
+MODULE_LICENSE("GPL");
diff --git a/drivers/gpio/dev-sync-probe.h b/drivers/gpio/dev-sync-probe.h
new file mode 100644
index 000000000000..4b3d52b70519
--- /dev/null
+++ b/drivers/gpio/dev-sync-probe.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef DEV_SYNC_PROBE_H
+#define DEV_SYNC_PROBE_H
+
+#include <linux/completion.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+
+struct dev_sync_probe_data {
+ struct platform_device *pdev;
+ const char *name;
+
+ /* Synchronize with probe */
+ struct notifier_block bus_notifier;
+ struct completion probe_completion;
+ bool driver_bound;
+};
+
+void dev_sync_probe_init(struct dev_sync_probe_data *data);
+int dev_sync_probe_register(struct dev_sync_probe_data *data,
+ struct platform_device_info *pdevinfo);
+void dev_sync_probe_unregister(struct dev_sync_probe_data *data);
+
+#endif /* DEV_SYNC_PROBE_H */
--
2.45.2
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