drivers: Add a new framework for multiplexer devices

Add a new subsystem that handles multiplexer controllers. The API is the
same as in Linux.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
[trini: Update some error calls to use different functions or pass
        correct arguments]
Signed-off-by: Tom Rini <trini@konsulko.com>

1 files changed, 147 insertions, 0 deletions

diff --git a/include/mux.h b/include/mux.h
new file mode 100644
index 0000000000..85eb7d42fc
--- /dev/null
+++ b/include/mux.h
@@ -0,0 +1,147 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Based on the linux multiplexer framework
+ *
+ * At its core, a multiplexer (or mux), also known as a data selector, is a
+ * device that selects between several analog or digital input signals and
+ * forwards it to a single output line. This notion can be extended to work
+ * with buses, like a I2C bus multiplexer for example.
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#ifndef _MUX_H_
+#define _MUX_H_
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct udevice;
+struct mux_control;
+
+#if CONFIG_IS_ENABLED(MULTIPLEXER)
+/**
+ * mux_control_states() - Query the number of multiplexer states.
+ * @mux: The mux-control to query.
+ *
+ * Return: The number of multiplexer states.
+ */
+unsigned int mux_control_states(struct mux_control *mux);
+
+/**
+ * mux_control_select() - Select the given multiplexer state.
+ * @mux: The mux-control to request a change of state from.
+ * @state: The new requested state.
+ *
+ * On successfully selecting the mux-control state, it will be locked until
+ * there is a call to mux_control_deselect(). If the mux-control is already
+ * selected when mux_control_select() is called, the function will indicate
+ * -EBUSY
+ *
+ * Therefore, make sure to call mux_control_deselect() when the operation is
+ * complete and the mux-control is free for others to use, but do not call
+ * mux_control_deselect() if mux_control_select() fails.
+ *
+ * Return: 0 when the mux-control state has the requested state or a negative
+ * errno on error.
+ */
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state);
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+/**
+ * mux_control_deselect() - Deselect the previously selected multiplexer state.
+ * @mux: The mux-control to deselect.
+ *
+ * It is required that a single call is made to mux_control_deselect() for
+ * each and every successful call made to either of mux_control_select() or
+ * mux_control_try_select().
+ *
+ * Return: 0 on success and a negative errno on error. An error can only
+ * occur if the mux has an idle state. Note that even if an error occurs, the
+ * mux-control is unlocked and is thus free for the next access.
+ */
+int mux_control_deselect(struct mux_control *mux);
+
+/**
+ * mux_get_by_index() = Get a mux by integer index.
+ * @dev: The client device.
+ * @index: The index of the mux to get.
+ * @mux: A pointer to the 'mux_control' struct to initialize.
+ *
+ * This looks up and initializes a mux. The index is relative to the client
+ * device.
+ *
+ * Return: 0 if OK, or a negative error code.
+ */
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux);
+
+/**
+ * mux_control_get() - Get the mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ * @mux: A pointer to the mux-control pointer.
+ *
+ * Return: 0 of OK, or a negative error code.
+ */
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux);
+
+/**
+ * mux_control_put() - Put away the mux-control for good.
+ * @mux: The mux-control to put away.
+ *
+ * mux_control_put() reverses the effects of mux_control_get().
+ */
+void mux_control_put(struct mux_control *mux);
+
+/**
+ * devm_mux_control_get() - Get the mux-control for a device, with resource
+ *			    management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name);
+#else
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state)
+{
+	return -ENOSYS;
+}
+
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+struct mux_control *mux_control_get(struct udevice *dev, const char *mux_name)
+{
+	return NULL;
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name)
+{
+	return NULL;
+}
+#endif
+
+#endif