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-rw-r--r--drivers/base/Makefile3
-rw-r--r--drivers/base/devcon.c136
2 files changed, 138 insertions, 1 deletions
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index e32a52490051..12a7f64d35a9 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -5,7 +5,8 @@ obj-y := component.o core.o bus.o dd.o syscore.o \
driver.o class.o platform.o \
cpu.o firmware.o init.o map.o devres.o \
attribute_container.o transport_class.o \
- topology.o container.o property.o cacheinfo.o
+ topology.o container.o property.o cacheinfo.o \
+ devcon.o
obj-$(CONFIG_DEVTMPFS) += devtmpfs.o
obj-$(CONFIG_DMA_CMA) += dma-contiguous.o
obj-y += power/
diff --git a/drivers/base/devcon.c b/drivers/base/devcon.c
new file mode 100644
index 000000000000..d427e806cd73
--- /dev/null
+++ b/drivers/base/devcon.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * Device connections
+ *
+ * Copyright (C) 2018 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ */
+
+#include <linux/device.h>
+
+static DEFINE_MUTEX(devcon_lock);
+static LIST_HEAD(devcon_list);
+
+/**
+ * device_connection_find_match - Find physical connection to a device
+ * @dev: Device with the connection
+ * @con_id: Identifier for the connection
+ * @data: Data for the match function
+ * @match: Function to check and convert the connection description
+ *
+ * Find a connection with unique identifier @con_id between @dev and another
+ * device. @match will be used to convert the connection description to data the
+ * caller is expecting to be returned.
+ */
+void *device_connection_find_match(struct device *dev, const char *con_id,
+ void *data,
+ void *(*match)(struct device_connection *con,
+ int ep, void *data))
+{
+ const char *devname = dev_name(dev);
+ struct device_connection *con;
+ void *ret = NULL;
+ int ep;
+
+ if (!match)
+ return NULL;
+
+ mutex_lock(&devcon_lock);
+
+ list_for_each_entry(con, &devcon_list, list) {
+ ep = match_string(con->endpoint, 2, devname);
+ if (ep < 0)
+ continue;
+
+ if (con_id && strcmp(con->id, con_id))
+ continue;
+
+ ret = match(con, !ep, data);
+ if (ret)
+ break;
+ }
+
+ mutex_unlock(&devcon_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(device_connection_find_match);
+
+extern struct bus_type platform_bus_type;
+extern struct bus_type pci_bus_type;
+extern struct bus_type i2c_bus_type;
+extern struct bus_type spi_bus_type;
+
+static struct bus_type *generic_match_buses[] = {
+ &platform_bus_type,
+#ifdef CONFIG_PCI
+ &pci_bus_type,
+#endif
+#ifdef CONFIG_I2C
+ &i2c_bus_type,
+#endif
+#ifdef CONFIG_SPI_MASTER
+ &spi_bus_type,
+#endif
+ NULL,
+};
+
+/* This tries to find the device from the most common bus types by name. */
+static void *generic_match(struct device_connection *con, int ep, void *data)
+{
+ struct bus_type *bus;
+ struct device *dev;
+
+ for (bus = generic_match_buses[0]; bus; bus++) {
+ dev = bus_find_device_by_name(bus, NULL, con->endpoint[ep]);
+ if (dev)
+ return dev;
+ }
+
+ /*
+ * We only get called if a connection was found, tell the caller to
+ * wait for the other device to show up.
+ */
+ return ERR_PTR(-EPROBE_DEFER);
+}
+
+/**
+ * device_connection_find - Find two devices connected together
+ * @dev: Device with the connection
+ * @con_id: Identifier for the connection
+ *
+ * Find a connection with unique identifier @con_id between @dev and
+ * another device. On success returns handle to the device that is connected
+ * to @dev, with the reference count for the found device incremented. Returns
+ * NULL if no matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a
+ * connection was found but the other device has not been enumerated yet.
+ */
+struct device *device_connection_find(struct device *dev, const char *con_id)
+{
+ return device_connection_find_match(dev, con_id, NULL, generic_match);
+}
+EXPORT_SYMBOL_GPL(device_connection_find);
+
+/**
+ * device_connection_add - Register a connection description
+ * @con: The connection description to be registered
+ */
+void device_connection_add(struct device_connection *con)
+{
+ mutex_lock(&devcon_lock);
+ list_add_tail(&con->list, &devcon_list);
+ mutex_unlock(&devcon_lock);
+}
+EXPORT_SYMBOL_GPL(device_connection_add);
+
+/**
+ * device_connections_remove - Unregister connection description
+ * @con: The connection description to be unregistered
+ */
+void device_connection_remove(struct device_connection *con)
+{
+ mutex_lock(&devcon_lock);
+ list_del(&con->list);
+ mutex_unlock(&devcon_lock);
+}
+EXPORT_SYMBOL_GPL(device_connection_remove);