linux-kernel - [PATCH 8/8] greybus: add function to probe p2p module

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Message-ID: <20251223183142.31897-9-damien.riegel@silabs.com>
Date: Tue, 23 Dec 2025 13:31:42 -0500
From: Damien Riégel <damien.riegel@...abs.com>
To: greybus-dev@...ts.linaro.org
Cc: linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        Alex Elder <elder@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-devel@...abs.com,
        Damien Riégel <damien.riegel@...abs.com>
Subject: [PATCH 8/8] greybus: add function to probe p2p module

In a normal Greybus topology, the enumeration of an interface would
start with a "Module Inserted" event, issued by the SVC. In a
point-to-point configuration, the SVC is absent and the host device must
enumerate the module manually.

In order to do so, export a new function that lets the host device
driver start the enumeration. Note that this function issues commands to
the module in a blocking way and should not be called in a probe
function, but should rather be called from a workqueue.

Signed-off-by: Damien Riégel <damien.riegel@...abs.com>
---
 drivers/greybus/hd.c       | 30 ++++++++++++++++++++++++++++++
 include/linux/greybus/hd.h |  2 ++
 2 files changed, 32 insertions(+)

diff --git a/drivers/greybus/hd.c b/drivers/greybus/hd.c
index 2fc9fbe987f..165775b6b8b 100644
--- a/drivers/greybus/hd.c
+++ b/drivers/greybus/hd.c
@@ -132,6 +132,36 @@ const struct device_type greybus_hd_type = {
 	.release	= gb_hd_release,
 };
 
+int gb_hd_p2p_probe_module(struct gb_host_device *hd)
+{
+	struct gb_module *module;
+	int ret;
+
+	if (!gb_hd_is_p2p(hd))
+		return -EOPNOTSUPP;
+
+	/* In P2P mode, only one module is supported. */
+	if (!list_empty(&hd->modules))
+		return -EBUSY;
+
+	module = gb_module_create_p2p(hd);
+	if (!module) {
+		dev_err(&hd->dev, "failed to create module\n");
+		return -ENOMEM;
+	}
+
+	ret = gb_module_add(module);
+	if (ret) {
+		gb_module_put(module);
+		return ret;
+	}
+
+	list_add(&module->hd_node, &hd->modules);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gb_hd_p2p_probe_module);
+
 struct gb_host_device *gb_hd_create_p2p(struct gb_hd_driver *driver,
 					struct device *parent,
 					size_t buffer_size_max,
diff --git a/include/linux/greybus/hd.h b/include/linux/greybus/hd.h
index 28ee7fca1d1..096b9642d11 100644
--- a/include/linux/greybus/hd.h
+++ b/include/linux/greybus/hd.h
@@ -83,6 +83,8 @@ void gb_hd_put(struct gb_host_device *hd);
 int gb_hd_output(struct gb_host_device *hd, void *req, u16 size, u8 cmd,
 		 bool in_irq);
 
+int gb_hd_p2p_probe_module(struct gb_host_device *hd);
+
 int gb_hd_init(void);
 void gb_hd_exit(void);
 
-- 
2.49.0