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541 lines
14 KiB
541 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Multiplexer subsystem |
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* |
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* Copyright (C) 2017 Axentia Technologies AB |
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* |
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* Author: Peter Rosin <[email protected]> |
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*/ |
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#define pr_fmt(fmt) "mux-core: " fmt |
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#include <linux/device.h> |
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#include <linux/err.h> |
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#include <linux/export.h> |
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#include <linux/idr.h> |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/mux/consumer.h> |
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#include <linux/mux/driver.h> |
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#include <linux/of.h> |
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#include <linux/of_platform.h> |
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#include <linux/slab.h> |
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/* |
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* The idle-as-is "state" is not an actual state that may be selected, it |
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* only implies that the state should not be changed. So, use that state |
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* as indication that the cached state of the multiplexer is unknown. |
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*/ |
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#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS |
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static struct class mux_class = { |
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.name = "mux", |
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.owner = THIS_MODULE, |
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}; |
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static DEFINE_IDA(mux_ida); |
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static int __init mux_init(void) |
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{ |
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ida_init(&mux_ida); |
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return class_register(&mux_class); |
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} |
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static void __exit mux_exit(void) |
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{ |
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class_unregister(&mux_class); |
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ida_destroy(&mux_ida); |
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} |
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static void mux_chip_release(struct device *dev) |
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{ |
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struct mux_chip *mux_chip = to_mux_chip(dev); |
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ida_simple_remove(&mux_ida, mux_chip->id); |
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kfree(mux_chip); |
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} |
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static const struct device_type mux_type = { |
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.name = "mux-chip", |
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.release = mux_chip_release, |
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}; |
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/** |
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* mux_chip_alloc() - Allocate a mux-chip. |
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* @dev: The parent device implementing the mux interface. |
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* @controllers: The number of mux controllers to allocate for this chip. |
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* @sizeof_priv: Size of extra memory area for private use by the caller. |
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* |
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* After allocating the mux-chip with the desired number of mux controllers |
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* but before registering the chip, the mux driver is required to configure |
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* the number of valid mux states in the mux_chip->mux[N].states members and |
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* the desired idle state in the returned mux_chip->mux[N].idle_state members. |
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* The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to |
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* provide a pointer to the operations struct in the mux_chip->ops member |
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* before registering the mux-chip with mux_chip_register. |
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* |
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* Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. |
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*/ |
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struct mux_chip *mux_chip_alloc(struct device *dev, |
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unsigned int controllers, size_t sizeof_priv) |
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{ |
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struct mux_chip *mux_chip; |
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int i; |
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if (WARN_ON(!dev || !controllers)) |
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return ERR_PTR(-EINVAL); |
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mux_chip = kzalloc(sizeof(*mux_chip) + |
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controllers * sizeof(*mux_chip->mux) + |
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sizeof_priv, GFP_KERNEL); |
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if (!mux_chip) |
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return ERR_PTR(-ENOMEM); |
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mux_chip->mux = (struct mux_control *)(mux_chip + 1); |
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mux_chip->dev.class = &mux_class; |
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mux_chip->dev.type = &mux_type; |
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mux_chip->dev.parent = dev; |
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mux_chip->dev.of_node = dev->of_node; |
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dev_set_drvdata(&mux_chip->dev, mux_chip); |
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mux_chip->id = ida_simple_get(&mux_ida, 0, 0, GFP_KERNEL); |
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if (mux_chip->id < 0) { |
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int err = mux_chip->id; |
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pr_err("muxchipX failed to get a device id\n"); |
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kfree(mux_chip); |
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return ERR_PTR(err); |
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} |
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dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id); |
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mux_chip->controllers = controllers; |
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for (i = 0; i < controllers; ++i) { |
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struct mux_control *mux = &mux_chip->mux[i]; |
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mux->chip = mux_chip; |
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sema_init(&mux->lock, 1); |
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mux->cached_state = MUX_CACHE_UNKNOWN; |
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mux->idle_state = MUX_IDLE_AS_IS; |
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} |
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device_initialize(&mux_chip->dev); |
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return mux_chip; |
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} |
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EXPORT_SYMBOL_GPL(mux_chip_alloc); |
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static int mux_control_set(struct mux_control *mux, int state) |
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{ |
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int ret = mux->chip->ops->set(mux, state); |
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mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state; |
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return ret; |
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} |
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/** |
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* mux_chip_register() - Register a mux-chip, thus readying the controllers |
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* for use. |
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* @mux_chip: The mux-chip to register. |
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* |
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* Do not retry registration of the same mux-chip on failure. You should |
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* instead put it away with mux_chip_free() and allocate a new one, if you |
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* for some reason would like to retry registration. |
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* |
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* Return: Zero on success or a negative errno on error. |
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*/ |
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int mux_chip_register(struct mux_chip *mux_chip) |
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{ |
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int i; |
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int ret; |
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for (i = 0; i < mux_chip->controllers; ++i) { |
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struct mux_control *mux = &mux_chip->mux[i]; |
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if (mux->idle_state == mux->cached_state) |
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continue; |
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ret = mux_control_set(mux, mux->idle_state); |
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if (ret < 0) { |
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dev_err(&mux_chip->dev, "unable to set idle state\n"); |
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return ret; |
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} |
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} |
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ret = device_add(&mux_chip->dev); |
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if (ret < 0) |
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dev_err(&mux_chip->dev, |
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"device_add failed in %s: %d\n", __func__, ret); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(mux_chip_register); |
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/** |
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* mux_chip_unregister() - Take the mux-chip off-line. |
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* @mux_chip: The mux-chip to unregister. |
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* |
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* mux_chip_unregister() reverses the effects of mux_chip_register(). |
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* But not completely, you should not try to call mux_chip_register() |
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* on a mux-chip that has been registered before. |
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*/ |
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void mux_chip_unregister(struct mux_chip *mux_chip) |
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{ |
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device_del(&mux_chip->dev); |
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} |
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EXPORT_SYMBOL_GPL(mux_chip_unregister); |
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/** |
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* mux_chip_free() - Free the mux-chip for good. |
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* @mux_chip: The mux-chip to free. |
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* |
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* mux_chip_free() reverses the effects of mux_chip_alloc(). |
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*/ |
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void mux_chip_free(struct mux_chip *mux_chip) |
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{ |
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if (!mux_chip) |
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return; |
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put_device(&mux_chip->dev); |
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} |
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EXPORT_SYMBOL_GPL(mux_chip_free); |
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static void devm_mux_chip_release(struct device *dev, void *res) |
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{ |
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struct mux_chip *mux_chip = *(struct mux_chip **)res; |
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mux_chip_free(mux_chip); |
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} |
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/** |
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* devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc(). |
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* @dev: The parent device implementing the mux interface. |
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* @controllers: The number of mux controllers to allocate for this chip. |
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* @sizeof_priv: Size of extra memory area for private use by the caller. |
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* |
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* See mux_chip_alloc() for more details. |
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* |
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* Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. |
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*/ |
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struct mux_chip *devm_mux_chip_alloc(struct device *dev, |
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unsigned int controllers, |
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size_t sizeof_priv) |
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{ |
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struct mux_chip **ptr, *mux_chip; |
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ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL); |
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if (!ptr) |
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return ERR_PTR(-ENOMEM); |
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mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv); |
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if (IS_ERR(mux_chip)) { |
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devres_free(ptr); |
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return mux_chip; |
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} |
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*ptr = mux_chip; |
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devres_add(dev, ptr); |
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return mux_chip; |
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} |
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EXPORT_SYMBOL_GPL(devm_mux_chip_alloc); |
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static void devm_mux_chip_reg_release(struct device *dev, void *res) |
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{ |
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struct mux_chip *mux_chip = *(struct mux_chip **)res; |
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mux_chip_unregister(mux_chip); |
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} |
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/** |
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* devm_mux_chip_register() - Resource-managed version mux_chip_register(). |
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* @dev: The parent device implementing the mux interface. |
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* @mux_chip: The mux-chip to register. |
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* |
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* See mux_chip_register() for more details. |
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* |
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* Return: Zero on success or a negative errno on error. |
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*/ |
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int devm_mux_chip_register(struct device *dev, |
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struct mux_chip *mux_chip) |
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{ |
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struct mux_chip **ptr; |
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int res; |
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ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL); |
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if (!ptr) |
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return -ENOMEM; |
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res = mux_chip_register(mux_chip); |
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if (res) { |
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devres_free(ptr); |
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return res; |
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} |
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*ptr = mux_chip; |
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devres_add(dev, ptr); |
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return res; |
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} |
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EXPORT_SYMBOL_GPL(devm_mux_chip_register); |
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/** |
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* mux_control_states() - Query the number of multiplexer states. |
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* @mux: The mux-control to query. |
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* |
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* Return: The number of multiplexer states. |
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*/ |
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unsigned int mux_control_states(struct mux_control *mux) |
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{ |
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return mux->states; |
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} |
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EXPORT_SYMBOL_GPL(mux_control_states); |
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/* |
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* The mux->lock must be down when calling this function. |
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*/ |
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static int __mux_control_select(struct mux_control *mux, int state) |
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{ |
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int ret; |
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if (WARN_ON(state < 0 || state >= mux->states)) |
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return -EINVAL; |
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if (mux->cached_state == state) |
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return 0; |
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ret = mux_control_set(mux, state); |
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if (ret >= 0) |
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return 0; |
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/* The mux update failed, try to revert if appropriate... */ |
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if (mux->idle_state != MUX_IDLE_AS_IS) |
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mux_control_set(mux, mux->idle_state); |
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return ret; |
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} |
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/** |
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* mux_control_select() - Select the given multiplexer state. |
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* @mux: The mux-control to request a change of state from. |
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* @state: The new requested state. |
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* |
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* On successfully selecting the mux-control state, it will be locked until |
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* there is a call to mux_control_deselect(). If the mux-control is already |
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* selected when mux_control_select() is called, the caller will be blocked |
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* until mux_control_deselect() is called (by someone else). |
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* |
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* Therefore, make sure to call mux_control_deselect() when the operation is |
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* complete and the mux-control is free for others to use, but do not call |
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* mux_control_deselect() if mux_control_select() fails. |
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* |
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* Return: 0 when the mux-control state has the requested state or a negative |
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* errno on error. |
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*/ |
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int mux_control_select(struct mux_control *mux, unsigned int state) |
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{ |
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int ret; |
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ret = down_killable(&mux->lock); |
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if (ret < 0) |
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return ret; |
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ret = __mux_control_select(mux, state); |
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if (ret < 0) |
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up(&mux->lock); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(mux_control_select); |
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/** |
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* mux_control_try_select() - Try to select the given multiplexer state. |
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* @mux: The mux-control to request a change of state from. |
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* @state: The new requested state. |
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* |
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* On successfully selecting the mux-control state, it will be locked until |
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* mux_control_deselect() called. |
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* |
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* Therefore, make sure to call mux_control_deselect() when the operation is |
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* complete and the mux-control is free for others to use, but do not call |
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* mux_control_deselect() if mux_control_try_select() fails. |
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* |
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* Return: 0 when the mux-control state has the requested state or a negative |
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* errno on error. Specifically -EBUSY if the mux-control is contended. |
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*/ |
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int mux_control_try_select(struct mux_control *mux, unsigned int state) |
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{ |
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int ret; |
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if (down_trylock(&mux->lock)) |
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return -EBUSY; |
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ret = __mux_control_select(mux, state); |
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if (ret < 0) |
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up(&mux->lock); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(mux_control_try_select); |
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/** |
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* mux_control_deselect() - Deselect the previously selected multiplexer state. |
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* @mux: The mux-control to deselect. |
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* |
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* It is required that a single call is made to mux_control_deselect() for |
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* each and every successful call made to either of mux_control_select() or |
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* mux_control_try_select(). |
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* |
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* Return: 0 on success and a negative errno on error. An error can only |
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* occur if the mux has an idle state. Note that even if an error occurs, the |
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* mux-control is unlocked and is thus free for the next access. |
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*/ |
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int mux_control_deselect(struct mux_control *mux) |
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{ |
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int ret = 0; |
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if (mux->idle_state != MUX_IDLE_AS_IS && |
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mux->idle_state != mux->cached_state) |
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ret = mux_control_set(mux, mux->idle_state); |
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up(&mux->lock); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(mux_control_deselect); |
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/* Note this function returns a reference to the mux_chip dev. */ |
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static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np) |
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{ |
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struct device *dev; |
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dev = class_find_device_by_of_node(&mux_class, np); |
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return dev ? to_mux_chip(dev) : NULL; |
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} |
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/** |
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* mux_control_get() - Get the mux-control for a device. |
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* @dev: The device that needs a mux-control. |
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* @mux_name: The name identifying the mux-control. |
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* |
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* Return: A pointer to the mux-control, or an ERR_PTR with a negative errno. |
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*/ |
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struct mux_control *mux_control_get(struct device *dev, const char *mux_name) |
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{ |
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struct device_node *np = dev->of_node; |
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struct of_phandle_args args; |
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struct mux_chip *mux_chip; |
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unsigned int controller; |
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int index = 0; |
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int ret; |
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if (mux_name) { |
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index = of_property_match_string(np, "mux-control-names", |
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mux_name); |
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if (index < 0) { |
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dev_err(dev, "mux controller '%s' not found\n", |
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mux_name); |
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return ERR_PTR(index); |
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} |
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} |
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ret = of_parse_phandle_with_args(np, |
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"mux-controls", "#mux-control-cells", |
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index, &args); |
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if (ret) { |
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dev_err(dev, "%pOF: failed to get mux-control %s(%i)\n", |
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np, mux_name ?: "", index); |
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return ERR_PTR(ret); |
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} |
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mux_chip = of_find_mux_chip_by_node(args.np); |
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of_node_put(args.np); |
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if (!mux_chip) |
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return ERR_PTR(-EPROBE_DEFER); |
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if (args.args_count > 1 || |
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(!args.args_count && (mux_chip->controllers > 1))) { |
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dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n", |
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np, args.np); |
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put_device(&mux_chip->dev); |
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return ERR_PTR(-EINVAL); |
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} |
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controller = 0; |
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if (args.args_count) |
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controller = args.args[0]; |
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if (controller >= mux_chip->controllers) { |
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dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n", |
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np, controller, args.np); |
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put_device(&mux_chip->dev); |
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return ERR_PTR(-EINVAL); |
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} |
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return &mux_chip->mux[controller]; |
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} |
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EXPORT_SYMBOL_GPL(mux_control_get); |
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/** |
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* mux_control_put() - Put away the mux-control for good. |
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* @mux: The mux-control to put away. |
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* |
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* mux_control_put() reverses the effects of mux_control_get(). |
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*/ |
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void mux_control_put(struct mux_control *mux) |
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{ |
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put_device(&mux->chip->dev); |
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} |
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EXPORT_SYMBOL_GPL(mux_control_put); |
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static void devm_mux_control_release(struct device *dev, void *res) |
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{ |
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struct mux_control *mux = *(struct mux_control **)res; |
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mux_control_put(mux); |
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} |
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/** |
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* devm_mux_control_get() - Get the mux-control for a device, with resource |
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* management. |
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* @dev: The device that needs a mux-control. |
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* @mux_name: The name identifying the mux-control. |
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* |
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* Return: Pointer to the mux-control, or an ERR_PTR with a negative errno. |
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*/ |
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struct mux_control *devm_mux_control_get(struct device *dev, |
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const char *mux_name) |
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{ |
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struct mux_control **ptr, *mux; |
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ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL); |
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if (!ptr) |
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return ERR_PTR(-ENOMEM); |
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mux = mux_control_get(dev, mux_name); |
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if (IS_ERR(mux)) { |
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devres_free(ptr); |
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return mux; |
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} |
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*ptr = mux; |
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devres_add(dev, ptr); |
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return mux; |
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} |
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EXPORT_SYMBOL_GPL(devm_mux_control_get); |
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|
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/* |
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* Using subsys_initcall instead of module_init here to try to ensure - for |
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* the non-modular case - that the subsystem is initialized when mux consumers |
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* and mux controllers start to use it. |
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* For the modular case, the ordering is ensured with module dependencies. |
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*/ |
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subsys_initcall(mux_init); |
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module_exit(mux_exit); |
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MODULE_DESCRIPTION("Multiplexer subsystem"); |
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MODULE_AUTHOR("Peter Rosin <[email protected]>"); |
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MODULE_LICENSE("GPL v2");
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