greybus: add module support

Modules in the greybus system sit above the interface, so insert them
early in the sysfs tree.  We dynamically create them when we have an
interface that references a module, as we don't get a "module create"
message directly.  They also dynamically go away when the last interface
associated with a module is removed.

Naming scheme for modules/interfaces/bundles/connections is bumped up by
one ':', and now looks like the following:

/sys/bus/greybus $ tree
.
├── devices
│   ├── 7 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-1/7
│   ├── 7:7 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-1/7/7:7
│   ├── 7:7:0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-1/7/7:7/7:7:0
│   └── 7:7:0:1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-1/7/7:7/7:7:0/7:7:0:1
├── drivers
├── drivers_autoprobe
├── drivers_probe
└── uevent

6 directories, 3 files
/sys/bus/greybus $ grep . devices/*/uevent
devices/7/uevent:DEVTYPE=greybus_module
devices/7:7/uevent:DEVTYPE=greybus_interface
devices/7:7:0/uevent:DEVTYPE=greybus_bundle
devices/7:7:0:1/uevent:DEVTYPE=greybus_connection

We still have some "confusion" about interface ids and module ids, which
will be cleaned up later when the svc control protocol changes die down,
right now we just name a module after the interface as we don't have any
modules that have multiple interfaces in our systems.

This has been tested with gbsim.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/drivers/staging/greybus/module.c b/drivers/staging/greybus/module.c
new file mode 100644
index 000000000000..625e2d436073
--- /dev/null
+++ b/drivers/staging/greybus/module.c
@@ -0,0 +1,140 @@
+/*
+ * Greybus module code
+ *
+ * Copyright 2014 Google Inc.
+ * Copyright 2014 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include "greybus.h"
+
+
+/*
+ * List of modules in the system.  We really should just walk the list the
+ * driver core provides us, but as we have lots of different things on the same
+ * "bus" at the same time, a single list of modules is simplest for now.
+ */
+static DEFINE_SPINLOCK(gb_modules_lock);
+static LIST_HEAD(module_list);
+
+/* module sysfs attributes */
+#define gb_module_attr(field, type)					\
+static ssize_t field##_show(struct device *dev,				\
+			    struct device_attribute *attr,		\
+			    char *buf)					\
+{									\
+	struct gb_module *module = to_gb_module(dev);			\
+	return sprintf(buf, "%"#type"\n", module->field);		\
+}									\
+static DEVICE_ATTR_RO(field)
+
+// FIXME, do we really need this attribute?
+gb_module_attr(module_id, x);
+
+static ssize_t epm_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	// FIXME, implement something here
+	return sprintf(buf, "1\n");
+}
+
+static ssize_t epm_store(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t size)
+{
+	// FIXME, implement something here.
+	return 0;
+}
+static DEVICE_ATTR_RW(epm);
+
+static struct attribute *module_attrs[] = {
+	&dev_attr_module_id.attr,
+	&dev_attr_epm.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(module);
+
+static void greybus_module_release(struct device *dev)
+{
+	struct gb_module *module = to_gb_module(dev);
+
+	spin_lock(&gb_modules_lock);
+	list_del(&module->list);
+	spin_unlock(&gb_modules_lock);
+
+	kfree(module);
+}
+
+struct device_type greybus_module_type = {
+	.name =		"greybus_module",
+	.release =	greybus_module_release,
+};
+
+/*
+ * Search the list of modules in the system.  If one is found, return it, with
+ * the reference count incremented.
+ */
+static struct gb_module *gb_module_find(u8 module_id)
+{
+	struct gb_module *module;
+
+	spin_lock(&gb_modules_lock);
+	list_for_each_entry(module, &module_list, list) {
+		if (module->module_id == module_id) {
+			get_device(&module->dev);
+			goto exit;
+		}
+	}
+	module = NULL;
+exit:
+	spin_unlock(&gb_modules_lock);
+	return module;
+}
+
+static struct gb_module *gb_module_create(struct greybus_host_device *hd,
+					  u8 module_id)
+{
+	struct gb_module *module;
+	int retval;
+
+	module = kzalloc(sizeof(*module), GFP_KERNEL);
+	if (!module)
+		return NULL;
+
+	module->module_id = module_id;
+	module->dev.parent = hd->parent;
+	module->dev.bus = &greybus_bus_type;
+	module->dev.type = &greybus_module_type;
+	module->dev.groups = module_groups;
+	module->dev.dma_mask = hd->parent->dma_mask;
+	device_initialize(&module->dev);
+	dev_set_name(&module->dev, "%d", module_id);
+
+	retval = device_add(&module->dev);
+	if (retval) {
+		pr_err("failed to add module device for id 0x%02hhx\n",
+			module_id);
+		put_device(&module->dev);
+		kfree(module);
+		return NULL;
+	}
+
+	spin_lock(&gb_modules_lock);
+	list_add_tail(&module->list, &module_list);
+	spin_unlock(&gb_modules_lock);
+
+	return module;
+}
+
+struct gb_module *gb_module_find_or_create(struct greybus_host_device *hd,
+					   u8 module_id)
+{
+	struct gb_module *module;
+
+	module = gb_module_find(module_id);
+	if (module)
+		return module;
+
+	return gb_module_create(hd, module_id);
+}
+