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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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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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