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>

3 files changed, 329 insertions, 0 deletions

diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
new file mode 100644
index 0000000000..35c1c5673c
--- /dev/null
+++ b/drivers/mux/Kconfig
@@ -0,0 +1,11 @@
+menu "Multiplexer drivers"
+
+config MULTIPLEXER
+	bool "Multiplexer Support"
+	depends on DM
+	help
+	 The mux framework is a minimalistic subsystem that handles multiplexer
+	 controllers. It provides the same API as Linux and mux drivers should
+	 be portable with a minimum effort.
+
+endmenu
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
new file mode 100644
index 0000000000..351e4363d3
--- /dev/null
+++ b/drivers/mux/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# (C) Copyright 2019
+# Jean-Jacques Hiblot <jjhiblot@ti.com>
+
+obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
new file mode 100644
index 0000000000..815df938aa
--- /dev/null
+++ b/drivers/mux/mux-uclass.c
@@ -0,0 +1,312 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Multiplexer subsystem
+ *
+ * Based on the linux multiplexer framework
+ *
+ * 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>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mux-internal.h>
+#include <dm/device-internal.h>
+#include <dm/device_compat.h>
+#include <dm/devres.h>
+#include <dt-bindings/mux/mux.h>
+#include <linux/bug.h>
+
+/*
+ * The idle-as-is "state" is not an actual state that may be selected, it
+ * only implies that the state should not be changed. So, use that state
+ * as indication that the cached state of the multiplexer is unknown.
+ */
+#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
+
+/**
+ * mux_control_ops() - Get the mux_control ops.
+ * @dev: The client device.
+ *
+ * Return: A pointer to the 'mux_control_ops' of the device.
+ */
+static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
+{
+	return (const struct mux_control_ops *)dev->driver->ops;
+}
+
+/**
+ * mux_control_set() - Set the state of the given mux controller.
+ * @mux: A multiplexer control
+ * @state: The new requested state.
+ *
+ * Return: 0 if OK, or a negative error code.
+ */
+static int mux_control_set(struct mux_control *mux, int state)
+{
+	int ret = mux_dev_ops(mux->dev)->set(mux, state);
+
+	mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
+
+	return ret;
+}
+
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return mux->states;
+}
+
+/**
+ * __mux_control_select() - Select the given multiplexer state.
+ * @mux: The mux-control to request a change of state from.
+ * @state: The new requested state.
+ *
+ * Try to set the mux to the requested state. If not, try to revert if
+ * appropriate.
+ */
+static int __mux_control_select(struct mux_control *mux, int state)
+{
+	int ret;
+
+	if (WARN_ON(state < 0 || state >= mux->states))
+		return -EINVAL;
+
+	if (mux->cached_state == state)
+		return 0;
+
+	ret = mux_control_set(mux, state);
+	if (ret >= 0)
+		return 0;
+
+	/* The mux update failed, try to revert if appropriate... */
+	if (mux->idle_state != MUX_IDLE_AS_IS)
+		mux_control_set(mux, mux->idle_state);
+
+	return ret;
+}
+
+int mux_control_select(struct mux_control *mux, unsigned int state)
+{
+	int ret;
+
+	if (mux->in_use)
+		return -EBUSY;
+
+	ret = __mux_control_select(mux, state);
+
+	if (ret < 0)
+		return ret;
+
+	mux->in_use = true;
+
+	return 0;
+}
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	int ret = 0;
+
+	if (mux->idle_state != MUX_IDLE_AS_IS &&
+	    mux->idle_state != mux->cached_state)
+		ret = mux_control_set(mux, mux->idle_state);
+
+	mux->in_use = false;
+
+	return ret;
+}
+
+static int mux_of_xlate_default(struct mux_chip *mux_chip,
+				struct ofnode_phandle_args *args,
+				struct mux_control **muxp)
+{
+	struct mux_control *mux;
+	int id;
+
+	log_debug("%s(muxp=%p)\n", __func__, muxp);
+
+	if (args->args_count > 1) {
+		debug("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		id = args->args[0];
+	else
+		id = 0;
+
+	if (id >= mux_chip->controllers) {
+		pr_err("bad mux controller %u specified in %s\n",
+			id, ofnode_get_name(args->node));
+		return -ERANGE;
+	}
+
+	mux = &mux_chip->mux[id];
+	mux->id = id;
+	*muxp = mux;
+	return 0;
+}
+
+/**
+ * mux_get_by_indexed_prop() - Get a mux control by integer index
+ * @dev: The client device.
+ * @prop_name: Name of the device tree property.
+ * @index: The index of the mux to get
+ * @mux: A pointer to the 'mux_control' struct to initialize.
+ *
+ * Return: 0 of OK, -errno otherwise.
+ */
+static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
+				   int index, struct mux_control **mux)
+{
+	int ret;
+	struct ofnode_phandle_args args;
+	struct udevice *dev_mux;
+	const struct mux_control_ops *ops;
+	struct mux_chip *mux_chip;
+
+	log_debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
+
+	ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
+					 0, index, &args);
+	if (ret) {
+		debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
+	if (ret) {
+		debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	mux_chip = dev_get_uclass_priv(dev_mux);
+
+	ops = mux_dev_ops(dev_mux);
+	if (ops->of_xlate)
+		ret = ops->of_xlate(mux_chip, &args, mux);
+	else
+		ret = mux_of_xlate_default(mux_chip, &args, mux);
+	if (ret) {
+		debug("of_xlate() failed: %d\n", ret);
+		return ret;
+	}
+	(*mux)->dev = dev_mux;
+
+	return 0;
+}
+
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
+{
+	return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
+}
+
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux)
+{
+	int index;
+
+	debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
+
+	index = dev_read_stringlist_search(dev, "mux-control-names", name);
+	if (index < 0) {
+		debug("fdt_stringlist_search() failed: %d\n", index);
+		return index;
+	}
+
+	return mux_get_by_index(dev, index, mux);
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+	mux_control_deselect(mux);
+}
+
+/**
+ * devm_mux_control_release() - Release the given managed mux.
+ * @dev: The client device.
+ * @res: Pointer to the mux to be released.
+ *
+ * This function is called by devres to release the mux. It reverses the
+ * effects of mux_control_get().
+ */
+static void devm_mux_control_release(struct udevice *dev, void *res)
+{
+	mux_control_put(*(struct mux_control **)res);
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
+{
+	int rc;
+	struct mux_control **mux;
+
+	mux = devres_alloc(devm_mux_control_release,
+			   sizeof(struct mux_control *), __GFP_ZERO);
+	if (unlikely(!mux))
+		return ERR_PTR(-ENOMEM);
+
+	rc = mux_control_get(dev, id, mux);
+	if (rc)
+		return ERR_PTR(rc);
+
+	devres_add(dev, mux);
+	return *mux;
+}
+
+int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
+{
+	int i;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	mux_chip->mux = devm_kmalloc(dev,
+				     sizeof(struct mux_control) * controllers,
+				     __GFP_ZERO);
+	if (!mux_chip->mux)
+		return -ENOMEM;
+
+	mux_chip->controllers = controllers;
+
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		mux->dev = dev;
+		mux->cached_state = MUX_CACHE_UNKNOWN;
+		mux->idle_state = MUX_IDLE_AS_IS;
+		mux->in_use = false;
+		mux->id = i;
+	}
+
+	return 0;
+}
+
+static int mux_uclass_post_probe(struct udevice *dev)
+{
+	int i, ret;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	/* Set all mux controllers to their idle state. */
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		if (mux->idle_state == mux->cached_state)
+			continue;
+
+		ret = mux_control_set(mux, mux->idle_state);
+		if (ret < 0) {
+			dev_err(dev, "unable to set idle state\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+UCLASS_DRIVER(mux) = {
+	.id		= UCLASS_MUX,
+	.name		= "mux",
+	.post_probe	= mux_uclass_post_probe,
+	.per_device_auto_alloc_size = sizeof(struct mux_chip),
+};