Re: [PATCH net-next v2 2/3] i3c: Add support for bus enumeration & notification

[Alexandre Belloni <alexandre.belloni@bootlin.com>]

On 17/07/2023 12:06:37+0800, Matt Johnston wrote:
> From: Jeremy Kerr <jk@codeconstruct.com.au>
> 
> This allows other drivers to be notified when new i3c busses are
> attached, referring to a whole i3c bus as opposed to individual
> devices.
> 
> Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
> Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>

Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
>  drivers/i3c/master.c       | 35 +++++++++++++++++++++++++++++++++++
>  include/linux/i3c/master.h | 11 +++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 08aeb69a7800..2276abe38bdc 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -22,6 +22,7 @@
>  static DEFINE_IDR(i3c_bus_idr);
>  static DEFINE_MUTEX(i3c_core_lock);
>  static int __i3c_first_dynamic_bus_num;
> +static BLOCKING_NOTIFIER_HEAD(i3c_bus_notifier);
>  
>  /**
>   * i3c_bus_maintenance_lock - Lock the bus for a maintenance operation
> @@ -453,6 +454,36 @@ static int i3c_bus_init(struct i3c_bus *i3cbus, struct device_node *np)
>  	return 0;
>  }
>  
> +void i3c_for_each_bus_locked(int (*fn)(struct i3c_bus *bus, void *data),
> +			     void *data)
> +{
> +	struct i3c_bus *bus;
> +	int id;
> +
> +	mutex_lock(&i3c_core_lock);
> +	idr_for_each_entry(&i3c_bus_idr, bus, id)
> +		fn(bus, data);
> +	mutex_unlock(&i3c_core_lock);
> +}
> +EXPORT_SYMBOL_GPL(i3c_for_each_bus_locked);
> +
> +int i3c_register_notifier(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_register(&i3c_bus_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(i3c_register_notifier);
> +
> +int i3c_unregister_notifier(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_unregister(&i3c_bus_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(i3c_unregister_notifier);
> +
> +static void i3c_bus_notify(struct i3c_bus *bus, unsigned int action)
> +{
> +	blocking_notifier_call_chain(&i3c_bus_notifier, action, bus);
> +}
> +
>  static const char * const i3c_bus_mode_strings[] = {
>  	[I3C_BUS_MODE_PURE] = "pure",
>  	[I3C_BUS_MODE_MIXED_FAST] = "mixed-fast",
> @@ -2678,6 +2709,8 @@ int i3c_master_register(struct i3c_master_controller *master,
>  	if (ret)
>  		goto err_del_dev;
>  
> +	i3c_bus_notify(i3cbus, I3C_NOTIFY_BUS_ADD);
> +
>  	/*
>  	 * We're done initializing the bus and the controller, we can now
>  	 * register I3C devices discovered during the initial DAA.
> @@ -2710,6 +2743,8 @@ EXPORT_SYMBOL_GPL(i3c_master_register);
>   */
>  void i3c_master_unregister(struct i3c_master_controller *master)
>  {
> +	i3c_bus_notify(&master->bus, I3C_NOTIFY_BUS_REMOVE);
> +
>  	i3c_master_i2c_adapter_cleanup(master);
>  	i3c_master_unregister_i3c_devs(master);
>  	i3c_master_bus_cleanup(master);
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 0b52da4f2346..db909ef79be4 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -24,6 +24,12 @@
>  
>  struct i2c_client;
>  
> +/* notifier actions. notifier call data is the struct i3c_bus */
> +enum {
> +	I3C_NOTIFY_BUS_ADD,
> +	I3C_NOTIFY_BUS_REMOVE,
> +};
> +
>  struct i3c_master_controller;
>  struct i3c_bus;
>  struct i3c_device;
> @@ -652,4 +658,9 @@ void i3c_master_queue_ibi(struct i3c_dev_desc *dev, struct i3c_ibi_slot *slot);
>  
>  struct i3c_ibi_slot *i3c_master_get_free_ibi_slot(struct i3c_dev_desc *dev);
>  
> +void i3c_for_each_bus_locked(int (*fn)(struct i3c_bus *bus, void *data),
> +			     void *data);
> +int i3c_register_notifier(struct notifier_block *nb);
> +int i3c_unregister_notifier(struct notifier_block *nb);
> +
>  #endif /* I3C_MASTER_H */
> -- 
> 2.37.2
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com