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    Subject[PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform
    Date
    On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
    (regulator, clock, pwm) have the same problem and solve this by allowing
    platform / board-setup code to add entries to a lookup table and then use
    this table to look things up.

    This commit adds support for getting a mux controller on a non DT platform
    following this pattern. It is based on a simplified version of the pwm
    subsys lookup code, the dev_id and mux_name parts of a lookup table entry
    are mandatory in the mux-core implementation.

    Signed-off-by: Hans de Goede <hdegoede@redhat.com>
    ---
    drivers/mux/core.c | 96 +++++++++++++++++++++++++++++++++++++++++++-
    include/linux/mux/consumer.h | 11 +++++
    2 files changed, 106 insertions(+), 1 deletion(-)

    diff --git a/drivers/mux/core.c b/drivers/mux/core.c
    index 6142493c327b..8864cc745506 100644
    --- a/drivers/mux/core.c
    +++ b/drivers/mux/core.c
    @@ -24,6 +24,9 @@
    #include <linux/of_platform.h>
    #include <linux/slab.h>

    +static DEFINE_MUTEX(mux_lookup_lock);
    +static LIST_HEAD(mux_lookup_list);
    +
    /*
    * 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
    @@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
    }
    EXPORT_SYMBOL_GPL(mux_control_deselect);

    +static int parent_name_match(struct device *dev, const void *data)
    +{
    + const char *parent_name = dev_name(dev->parent);
    + const char *name = data;
    +
    + return strcmp(parent_name, name) == 0;
    +}
    +
    +static struct mux_chip *mux_chip_get_by_name(const char *name)
    +{
    + struct device *dev;
    +
    + dev = class_find_device(&mux_class, NULL, name, parent_name_match);
    +
    + return dev ? to_mux_chip(dev) : NULL;
    +}
    +
    static int of_dev_node_match(struct device *dev, const void *data)
    {
    return dev->of_node == data;
    @@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct device *dev,
    }

    /**
    + * mux_add_table() - register PWM device consumers
    + * @table: array of consumers to register
    + * @num: number of consumers in table
    + */
    +void mux_add_table(struct mux_lookup *table, size_t num)
    +{
    + mutex_lock(&mux_lookup_lock);
    +
    + while (num--) {
    + list_add_tail(&table->list, &mux_lookup_list);
    + table++;
    + }
    +
    + mutex_unlock(&mux_lookup_lock);
    +}
    +EXPORT_SYMBOL_GPL(mux_add_table);
    +
    +/**
    + * mux_remove_table() - unregister PWM device consumers
    + * @table: array of consumers to unregister
    + * @num: number of consumers in table
    + */
    +void mux_remove_table(struct mux_lookup *table, size_t num)
    +{
    + mutex_lock(&mux_lookup_lock);
    +
    + while (num--) {
    + list_del(&table->list);
    + table++;
    + }
    +
    + mutex_unlock(&mux_lookup_lock);
    +}
    +EXPORT_SYMBOL_GPL(mux_remove_table);
    +
    +/**
    * 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.
    @@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct device *dev,
    */
    struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
    {
    + struct mux_lookup *m, *chosen = NULL;
    + const char *dev_id = dev_name(dev);
    + struct mux_chip *mux_chip;
    +
    /* look up via DT first */
    if (IS_ENABLED(CONFIG_OF) && dev->of_node)
    return of_mux_control_get(dev, mux_name);

    - return ERR_PTR(-ENODEV);
    + /*
    + * For non DT we look up the provider in the static table typically
    + * provided by board setup code.
    + *
    + * If a match is found, the provider mux chip is looked up by name
    + * and a mux-control is requested using the table provided index.
    + */
    + mutex_lock(&mux_lookup_lock);
    + list_for_each_entry(m, &mux_lookup_list, list) {
    + if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
    + continue;
    +
    + if (strcmp(m->dev_id, dev_id) == 0 &&
    + strcmp(m->mux_name, mux_name) == 0) {
    + chosen = m;
    + break;
    + }
    + }
    + mutex_unlock(&mux_lookup_lock);
    +
    + if (!chosen)
    + return ERR_PTR(-ENODEV);
    +
    + mux_chip = mux_chip_get_by_name(chosen->provider);
    + if (!mux_chip)
    + return ERR_PTR(-EPROBE_DEFER);
    +
    + if (chosen->index >= mux_chip->controllers) {
    + dev_err(dev, "Mux lookup table index out of bounds %u >= %u\n",
    + chosen->index, mux_chip->controllers);
    + put_device(&mux_chip->dev);
    + return ERR_PTR(-EINVAL);
    + }
    +
    + return &mux_chip->mux[chosen->index];
    }
    EXPORT_SYMBOL_GPL(mux_control_get);

    diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
    index ea96d4c82be7..912dd48a3a5d 100644
    --- a/include/linux/mux/consumer.h
    +++ b/include/linux/mux/consumer.h
    @@ -18,6 +18,17 @@
    struct device;
    struct mux_control;

    +struct mux_lookup {
    + struct list_head list;
    + const char *provider;
    + unsigned int index;
    + const char *dev_id;
    + const char *mux_name;
    +};
    +
    +void mux_add_table(struct mux_lookup *table, size_t num);
    +void mux_remove_table(struct mux_lookup *table, size_t num);
    +
    unsigned int mux_control_states(struct mux_control *mux);
    int __must_check mux_control_select(struct mux_control *mux,
    unsigned int state);
    --
    2.13.5
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