greybus: core: add module abstraction

Add Greybus module abstraction that will be used to implement controlled
module removal (eject) and represent module geometry.

Greybus module devices correspond to physical modules and have one or
more interfaces. Modules have an id that is identical to the id of their
primary interface, which in turn is the interface with lowest numbered
id. The module name is constructed from the bus and module id:

        <bus_id>-<module_id>

Interfaces, bundles, and control devices are consequently renamed as

        <bus_id>-<module_id>.<interface_id>
        <bus_id>-<module_id>.<interface_id>.<bundle_id>
        <bus_id>-<module_id>.<interface_id>.ctrl

As before, interface ids (and therefore in a sense now also module ids)
correspond to physical interface positions on the frame.

Modules have the following attributes:

        module_id
        num_interfaces

where module_id is the id of the module and num_interface the number of
interfaces the module has.

Note that until SVC module-size detection has been implemented, all
interfaces are considered to be part of 1x2 modules. Specifically, the
two interfaces of a 2x2 module will be presented as two 1x2 modules for
now.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 178 insertions, 0 deletions

diff --git a/drivers/staging/greybus/module.c b/drivers/staging/greybus/module.c
new file mode 100644
index 000000000000..5c498e0a4eaf
--- /dev/null
+++ b/drivers/staging/greybus/module.c
@@ -0,0 +1,178 @@
+/*
+ * Greybus Module code
+ *
+ * Copyright 2016 Google Inc.
+ * Copyright 2016 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include "greybus.h"
+
+
+static ssize_t module_id_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct gb_module *module = to_gb_module(dev);
+
+	return sprintf(buf, "%u\n", module->module_id);
+}
+static DEVICE_ATTR_RO(module_id);
+
+static ssize_t num_interfaces_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct gb_module *module = to_gb_module(dev);
+
+	return sprintf(buf, "%zu\n", module->num_interfaces);
+}
+static DEVICE_ATTR_RO(num_interfaces);
+
+static struct attribute *module_attrs[] = {
+	&dev_attr_module_id.attr,
+	&dev_attr_num_interfaces.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(module);
+
+static void gb_module_release(struct device *dev)
+{
+	struct gb_module *module = to_gb_module(dev);
+
+	kfree(module);
+}
+
+struct device_type greybus_module_type = {
+	.name		= "greybus_module",
+	.release	= gb_module_release,
+};
+
+struct gb_module *gb_module_create(struct gb_host_device *hd, u8 module_id,
+					size_t num_interfaces)
+{
+	struct gb_interface *intf;
+	struct gb_module *module;
+	int i;
+
+	module = kzalloc(sizeof(*module) + num_interfaces * sizeof(intf),
+				GFP_KERNEL);
+	if (!module)
+		return NULL;
+
+	module->hd = hd;
+	module->module_id = module_id;
+	module->num_interfaces = num_interfaces;
+
+	module->dev.parent = &hd->dev;
+	module->dev.bus = &greybus_bus_type;
+	module->dev.type = &greybus_module_type;
+	module->dev.groups = module_groups;
+	module->dev.dma_mask = hd->dev.dma_mask;
+	device_initialize(&module->dev);
+	dev_set_name(&module->dev, "%d-%u", hd->bus_id, module_id);
+
+	for (i = 0; i < num_interfaces; ++i) {
+		intf = gb_interface_create(module, module_id + i);
+		if (!intf) {
+			dev_err(&module->dev, "failed to create interface %u\n",
+					module_id + i);
+			goto err_put_interfaces;
+		}
+		module->interfaces[i] = intf;
+	}
+
+	return module;
+
+err_put_interfaces:
+	for (--i; i > 0; --i)
+		gb_interface_put(module->interfaces[i]);
+
+	put_device(&module->dev);
+
+	return NULL;
+}
+
+/*
+ * Register and enable an interface after first attempting to activate it.
+ */
+static void gb_module_register_interface(struct gb_interface *intf)
+{
+	struct gb_module *module = intf->module;
+	u8 intf_id = intf->interface_id;
+	int ret;
+
+	ret = gb_interface_activate(intf);
+	if (ret) {
+		dev_err(&module->dev, "failed to activate interface %u: %d\n",
+				intf_id, ret);
+		gb_interface_add(intf);
+		return;
+	}
+
+	ret = gb_interface_add(intf);
+	if (ret)
+		goto err_interface_deactivate;
+
+	ret = gb_interface_enable(intf);
+	if (ret) {
+		dev_err(&module->dev, "failed to enable interface %u: %d\n",
+				intf_id, ret);
+		goto err_interface_deactivate;
+	}
+
+	return;
+
+err_interface_deactivate:
+	gb_interface_deactivate(intf);
+}
+
+static void gb_module_deregister_interface(struct gb_interface *intf)
+{
+	/* Mark as disconnected to prevent I/O during disable. */
+	if (intf->module->disconnected)
+		intf->disconnected = true;
+
+	gb_interface_disable(intf);
+	gb_interface_deactivate(intf);
+
+	gb_interface_del(intf);
+}
+
+/* Register a module and its interfaces. */
+int gb_module_add(struct gb_module *module)
+{
+	size_t i;
+	int ret;
+
+	ret = device_add(&module->dev);
+	if (ret) {
+		dev_err(&module->dev, "failed to register module: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < module->num_interfaces; ++i)
+		gb_module_register_interface(module->interfaces[i]);
+
+	return 0;
+}
+
+/* Deregister a module and its interfaces. */
+void gb_module_del(struct gb_module *module)
+{
+	size_t i;
+
+	for (i = 0; i < module->num_interfaces; ++i)
+		gb_module_deregister_interface(module->interfaces[i]);
+
+	device_del(&module->dev);
+}
+
+void gb_module_put(struct gb_module *module)
+{
+	size_t i;
+
+	for (i = 0; i < module->num_interfaces; ++i)
+		gb_interface_put(module->interfaces[i]);
+
+	put_device(&module->dev);
+}