usb: add bus type for USB ULPI

UTMI+ Low Pin Interface (ULPI) is a commonly used PHY
interface for USB 2.0. The ULPI specification describes a
standard set of registers which the vendors can extend for
their specific needs. ULPI PHYs provide often functions
such as charger detection and ADP sensing and probing.

There are two major issues that the bus type is meant to
tackle:

Firstly, ULPI registers are accessed from the controller.
The bus provides convenient method for the controller
drivers to share that access with the actual PHY drivers.

Secondly, there are already platforms that assume ULPI PHYs
are runtime detected, such as many Intel Baytrail based
platforms. They do not provide any kind of hardware
description for the ULPI PHYs like separate ACPI device
object that could be used to enumerate a device from.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/ulpi/interface.h b/include/linux/ulpi/interface.h
new file mode 100644
index 000000000000..4de8ab491038
--- /dev/null
+++ b/include/linux/ulpi/interface.h
@@ -0,0 +1,23 @@
+#ifndef __LINUX_ULPI_INTERFACE_H
+#define __LINUX_ULPI_INTERFACE_H
+
+#include <linux/types.h>
+
+struct ulpi;
+
+/**
+ * struct ulpi_ops - ULPI register access
+ * @dev: the interface provider
+ * @read: read operation for ULPI register access
+ * @write: write operation for ULPI register access
+ */
+struct ulpi_ops {
+	struct device *dev;
+	int (*read)(struct ulpi_ops *ops, u8 addr);
+	int (*write)(struct ulpi_ops *ops, u8 addr, u8 val);
+};
+
+struct ulpi *ulpi_register_interface(struct device *, struct ulpi_ops *);
+void ulpi_unregister_interface(struct ulpi *);
+
+#endif /* __LINUX_ULPI_INTERFACE_H */