[v6,1/8] i2c: core: let adapters be notified of client attach/detach
Commit Message
From: Luca Ceresoli <luca@lucaceresoli.net>
An adapter might need to know when a new device is about to be
added. This will soon bee needed to implement an "I2C address
translator" (ATR for short), a device that propagates I2C transactions
with a different slave address (an "alias" address). An ATR driver
needs to know when a slave is being added to find a suitable alias and
program the device translation map.
Add an attach/detach callback pair to allow adapter drivers to be
notified of clients being added and removed.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
drivers/i2c/i2c-core-base.c | 21 ++++++++++++++++++++-
include/linux/i2c.h | 16 ++++++++++++++++
2 files changed, 36 insertions(+), 1 deletion(-)
Comments
Hi Tomi,
Thank you for the patch.
On Thu, Jan 05, 2023 at 04:03:00PM +0200, Tomi Valkeinen wrote:
> From: Luca Ceresoli <luca@lucaceresoli.net>
>
> An adapter might need to know when a new device is about to be
> added. This will soon bee needed to implement an "I2C address
> translator" (ATR for short), a device that propagates I2C transactions
> with a different slave address (an "alias" address). An ATR driver
> needs to know when a slave is being added to find a suitable alias and
> program the device translation map.
>
> Add an attach/detach callback pair to allow adapter drivers to be
> notified of clients being added and removed.
I've asked in the review of v6 if we could instead use the
BUS_NOTIFY_ADD_DEVICE and BUS_NOTIFY_DEL_DEVICE bus notifiers. There's
been a follow up discussion with Andy, but no reply from you AFAICS.
Have you given this a try ? It's not a mandatory requirement, but if it
can't be done (or shouldn't be done), I'd like to know why.
> Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
> drivers/i2c/i2c-core-base.c | 21 ++++++++++++++++++++-
> include/linux/i2c.h | 16 ++++++++++++++++
> 2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 7539b0740351..8a0888ba89e5 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -916,6 +916,7 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
> struct i2c_client *
> i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> {
> + const struct i2c_attach_operations *attach_ops;
> struct i2c_client *client;
> int status;
>
> @@ -967,15 +968,24 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
> }
> }
>
> + attach_ops = adap->attach_ops;
> +
> + if (attach_ops && attach_ops->attach_client &&
> + attach_ops->attach_client(adap, info, client))
> + goto out_remove_swnode;
> +
> status = device_register(&client->dev);
> if (status)
> - goto out_remove_swnode;
> + goto out_detach_client;
>
> dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
> client->name, dev_name(&client->dev));
>
> return client;
>
> +out_detach_client:
> + if (attach_ops && attach_ops->detach_client)
> + attach_ops->detach_client(adap, client);
> out_remove_swnode:
> device_remove_software_node(&client->dev);
> out_err_put_of_node:
> @@ -997,9 +1007,18 @@ EXPORT_SYMBOL_GPL(i2c_new_client_device);
> */
> void i2c_unregister_device(struct i2c_client *client)
> {
> + const struct i2c_attach_operations *attach_ops;
> + struct i2c_adapter *adap;
> +
> if (IS_ERR_OR_NULL(client))
> return;
>
> + adap = client->adapter;
> + attach_ops = adap->attach_ops;
> +
> + if (attach_ops && attach_ops->detach_client)
> + attach_ops->detach_client(adap, client);
> +
> if (client->dev.of_node) {
> of_node_clear_flag(client->dev.of_node, OF_POPULATED);
> of_node_put(client->dev.of_node);
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index f7c49bbdb8a1..9a385b6de388 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -584,6 +584,21 @@ struct i2c_lock_operations {
> void (*unlock_bus)(struct i2c_adapter *adapter, unsigned int flags);
> };
>
> +/**
> + * struct i2c_attach_operations - callbacks to notify client attach/detach
> + * @attach_client: Notify of new client being attached
> + * @detach_client: Notify of new client being detached
> + *
> + * Both ops are optional.
> + */
> +struct i2c_attach_operations {
> + int (*attach_client)(struct i2c_adapter *adapter,
> + const struct i2c_board_info *info,
> + const struct i2c_client *client);
> + void (*detach_client)(struct i2c_adapter *adapter,
> + const struct i2c_client *client);
> +};
> +
> /**
> * struct i2c_timings - I2C timing information
> * @bus_freq_hz: the bus frequency in Hz
> @@ -726,6 +741,7 @@ struct i2c_adapter {
>
> /* data fields that are valid for all devices */
> const struct i2c_lock_operations *lock_ops;
> + const struct i2c_attach_operations *attach_ops;
> struct rt_mutex bus_lock;
> struct rt_mutex mux_lock;
>
On 08/01/2023 05:13, Laurent Pinchart wrote:
> Hi Tomi,
>
> Thank you for the patch.
>
> On Thu, Jan 05, 2023 at 04:03:00PM +0200, Tomi Valkeinen wrote:
>> From: Luca Ceresoli <luca@lucaceresoli.net>
>>
>> An adapter might need to know when a new device is about to be
>> added. This will soon bee needed to implement an "I2C address
>> translator" (ATR for short), a device that propagates I2C transactions
>> with a different slave address (an "alias" address). An ATR driver
>> needs to know when a slave is being added to find a suitable alias and
>> program the device translation map.
>>
>> Add an attach/detach callback pair to allow adapter drivers to be
>> notified of clients being added and removed.
>
> I've asked in the review of v6 if we could instead use the
> BUS_NOTIFY_ADD_DEVICE and BUS_NOTIFY_DEL_DEVICE bus notifiers. There's
> been a follow up discussion with Andy, but no reply from you AFAICS.
> Have you given this a try ? It's not a mandatory requirement, but if it
> can't be done (or shouldn't be done), I'd like to know why.
Sorry, I meant to mention this in the cover letter, but forgot:
I haven't looked at the bus notifiers yet, but will have a look. I
wanted to send a new revision due to the large amount of changes already
done.
Tomi
@@ -916,6 +916,7 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
struct i2c_client *
i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
+ const struct i2c_attach_operations *attach_ops;
struct i2c_client *client;
int status;
@@ -967,15 +968,24 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
}
}
+ attach_ops = adap->attach_ops;
+
+ if (attach_ops && attach_ops->attach_client &&
+ attach_ops->attach_client(adap, info, client))
+ goto out_remove_swnode;
+
status = device_register(&client->dev);
if (status)
- goto out_remove_swnode;
+ goto out_detach_client;
dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
client->name, dev_name(&client->dev));
return client;
+out_detach_client:
+ if (attach_ops && attach_ops->detach_client)
+ attach_ops->detach_client(adap, client);
out_remove_swnode:
device_remove_software_node(&client->dev);
out_err_put_of_node:
@@ -997,9 +1007,18 @@ EXPORT_SYMBOL_GPL(i2c_new_client_device);
*/
void i2c_unregister_device(struct i2c_client *client)
{
+ const struct i2c_attach_operations *attach_ops;
+ struct i2c_adapter *adap;
+
if (IS_ERR_OR_NULL(client))
return;
+ adap = client->adapter;
+ attach_ops = adap->attach_ops;
+
+ if (attach_ops && attach_ops->detach_client)
+ attach_ops->detach_client(adap, client);
+
if (client->dev.of_node) {
of_node_clear_flag(client->dev.of_node, OF_POPULATED);
of_node_put(client->dev.of_node);
@@ -584,6 +584,21 @@ struct i2c_lock_operations {
void (*unlock_bus)(struct i2c_adapter *adapter, unsigned int flags);
};
+/**
+ * struct i2c_attach_operations - callbacks to notify client attach/detach
+ * @attach_client: Notify of new client being attached
+ * @detach_client: Notify of new client being detached
+ *
+ * Both ops are optional.
+ */
+struct i2c_attach_operations {
+ int (*attach_client)(struct i2c_adapter *adapter,
+ const struct i2c_board_info *info,
+ const struct i2c_client *client);
+ void (*detach_client)(struct i2c_adapter *adapter,
+ const struct i2c_client *client);
+};
+
/**
* struct i2c_timings - I2C timing information
* @bus_freq_hz: the bus frequency in Hz
@@ -726,6 +741,7 @@ struct i2c_adapter {
/* data fields that are valid for all devices */
const struct i2c_lock_operations *lock_ops;
+ const struct i2c_attach_operations *attach_ops;
struct rt_mutex bus_lock;
struct rt_mutex mux_lock;