Re: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 02-09-17 21:13, sathya wrote:
> Hi,
> 
> 
> On 09/01/2017 02:48 PM, 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);
> Device name usually contains id section (devname.id). Did you take this into consideration ?
>> +    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
> PWM -> MUX

Thank you, good catch, fixed for v2.

Regards,

Hans


>> + * @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);
>