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    SubjectRe: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform
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    Date
    Hi!

    Some comments inline...

    On 2017-09-01 23:48, Hans de Goede wrote:
    > 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

    register mux controllers (because you are not registering consumers, right?
    someone is registering controllers so that they can be found by consumers?)

    > + * @table: array of consumers to register
    > + * @num: number of consumers in table

    controllers?

    > + */
    > +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++;
    > + }

    I prefer

    for (; num--; table++)
    list_add_tail(&table->list, &mux_lookup_list);

    > +
    > + mutex_unlock(&mux_lookup_lock);
    > +}
    > +EXPORT_SYMBOL_GPL(mux_add_table);
    > +
    > +/**
    > + * mux_remove_table() - unregister PWM device consumers

    unregister mux controllers(?)

    > + * @table: array of consumers to unregister
    > + * @num: number of consumers in table

    controllers?

    > + */
    > +void mux_remove_table(struct mux_lookup *table, size_t num)
    > +{
    > + mutex_lock(&mux_lookup_lock);
    > +
    > + while (num--) {
    > + list_del(&table->list);
    > + table++;
    > + }

    for() loop here as well.

    > +
    > + 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) {

    I want the below format (with ! instead of == 0 and the brace on the next line
    when the condition has a line break):

    if (!strcmp(m->dev_id, dev_id) &&
    !strcmp(m->mux_name, mux_name))
    {

    > + 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;
    >

    I want a kernel-doc comment here, describing the structure.

    > +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);
    > +

    I'm not sure if consumer.h is the right place for this, but it can
    be moved when I think of something better. Which I can't for the
    moment...

    > unsigned int mux_control_states(struct mux_control *mux);
    > int __must_check mux_control_select(struct mux_control *mux,
    > unsigned int state);
    >

    Cheers,
    Peter
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