v4.19.13 snapshot.
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
new file mode 100644
index 0000000..bd74d57
--- /dev/null
+++ b/include/linux/i2c-mux.h
@@ -0,0 +1,80 @@
+/*
+ *
+ * i2c-mux.h - functions for the i2c-bus mux support
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ * Michael Lawnick <michael.lawnick.ext@nsn.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA.
+ */
+
+#ifndef _LINUX_I2C_MUX_H
+#define _LINUX_I2C_MUX_H
+
+#ifdef __KERNEL__
+
+#include <linux/bitops.h>
+
+struct i2c_mux_core {
+ struct i2c_adapter *parent;
+ struct device *dev;
+ unsigned int mux_locked:1;
+ unsigned int arbitrator:1;
+ unsigned int gate:1;
+
+ void *priv;
+
+ int (*select)(struct i2c_mux_core *, u32 chan_id);
+ int (*deselect)(struct i2c_mux_core *, u32 chan_id);
+
+ int num_adapters;
+ int max_adapters;
+ struct i2c_adapter *adapter[0];
+};
+
+struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
+ struct device *dev, int max_adapters,
+ int sizeof_priv, u32 flags,
+ int (*select)(struct i2c_mux_core *, u32),
+ int (*deselect)(struct i2c_mux_core *, u32));
+
+/* flags for i2c_mux_alloc */
+#define I2C_MUX_LOCKED BIT(0)
+#define I2C_MUX_ARBITRATOR BIT(1)
+#define I2C_MUX_GATE BIT(2)
+
+static inline void *i2c_mux_priv(struct i2c_mux_core *muxc)
+{
+ return muxc->priv;
+}
+
+struct i2c_adapter *i2c_root_adapter(struct device *dev);
+
+/*
+ * Called to create an i2c bus on a multiplexed bus segment.
+ * The chan_id parameter is passed to the select and deselect
+ * callback functions to perform hardware-specific mux control.
+ */
+int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
+ u32 force_nr, u32 chan_id,
+ unsigned int class);
+
+void i2c_mux_del_adapters(struct i2c_mux_core *muxc);
+
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_I2C_MUX_H */