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Date: Fri, 6 Nov 2020 11:07:17 -0500
From: Thara Gopinath <thara.gopinath@...aro.org>
To: Cristian Marussi <cristian.marussi@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
sudeep.holla@....com, lukasz.luba@....com,
james.quinlan@...adcom.com, Jonathan.Cameron@...wei.com,
f.fainelli@...il.com, etienne.carriere@...aro.org,
vincent.guittot@...aro.org, souvik.chakravarty@....com
Subject: Re: [PATCH v2 3/8] firmware: arm_scmi: introduce new protocol
operations support
On 11/4/20 1:08 PM, Cristian Marussi wrote:
> Hi,
>
> On Wed, Nov 04, 2020 at 11:16:31AM -0500, Thara Gopinath wrote:
>> Hi Cristian,
>>
>> On 10/28/20 4:29 PM, Cristian Marussi wrote:
>>> Expose a new generic get/put protocols API based on protocol handles;
>>> provide also a devres managed version also for notifications.
>>
>> minor nit.. Maybe yous should reword this! Kind of confusing to understand!
>>
>> Also, if it was me, I will separate the notifications and get/put hooks
>> into two separate patches. Not an issue though if you want to keep it
>> in the same patch.
>
> You're right I have to reword the commit message, and I'll review the
> possibility of a further split, even though many parts of this series
> are tightly bound together given the kind of changes so sometimes to
> avoid breaking bisectability I had to push painfully long patches (like
> 6/8 :< )...but maybe I've got it wrong and this is not the case here.
>
>>
>>> All SCMI drivers still keep using the old handle based interface.
>>>
>>> Signed-off-by: Cristian Marussi <cristian.marussi@....com>
>>> ---
>>> drivers/firmware/arm_scmi/driver.c | 126 +++++++++++++++++++++++++++++
>>> drivers/firmware/arm_scmi/notify.c | 123 ++++++++++++++++++++++++++++
>>> include/linux/scmi_protocol.h | 34 +++++++-
>>> 3 files changed, 282 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
>>> index 8ca04acb6abb..4d86aafbf465 100644
>>> --- a/drivers/firmware/arm_scmi/driver.c
>>> +++ b/drivers/firmware/arm_scmi/driver.c
>>> @@ -15,6 +15,7 @@
>>> */
>>> #include <linux/bitmap.h>
>>> +#include <linux/device.h>
>>> #include <linux/export.h>
>>> #include <linux/idr.h>
>>> #include <linux/io.h>
>>> @@ -728,6 +729,38 @@ void scmi_release_protocol(struct scmi_handle *handle, u8 protocol_id)
>>> mutex_unlock(&info->protocols_mtx);
>>> }
>>> +/**
>>> + * scmi_get_protocol_operations - Get protocol operations
>>> + * @handle: A reference to the SCMI platform instance.
>>> + * @protocol_id: The protocol being requested.
>>> + * @ph: A pointer reference used to pass back the associated protocol handle.
>>> + *
>>> + * Get hold of a protocol accounting for its usage, eventually triggering its
>>> + * initialization, and returning the protocol specific operations and related
>>> + * protocol handle which will be used as first argument in most of the protocols
>>> + * operations methods.
>>> + *
>>> + * Return: A reference to the requested protocol operations or error.
>>> + * Must be checked for errors by caller.
>>> + */
>>> +static const void __must_check *
>>> +scmi_get_protocol_operations(struct scmi_handle *handle, u8 protocol_id,
>>> + struct scmi_protocol_handle **ph)
>>> +{
>>> + struct scmi_protocol_instance *pi;
>>> +
>>> + if (!ph)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + pi = scmi_get_protocol_instance(handle, protocol_id);
>>> + if (IS_ERR(pi))
>>> + return pi;
>>> +
>>> + *ph = &pi->ph;
>>> +
>>> + return pi->proto->ops;
>>> +}
>>> +
>>> void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
>>> u8 *prot_imp)
>>> {
>>> @@ -751,6 +784,95 @@ scmi_is_protocol_implemented(const struct scmi_handle *handle, u8 prot_id)
>>> return false;
>>> }
>>> +struct scmi_protocol_devres {
>>> + struct scmi_handle *handle;
>>> + u8 protocol_id;
>>> +};
>>> +
>>> +static void scmi_devm_release_protocol(struct device *dev, void *res)
>>> +{
>>> + struct scmi_protocol_devres *dres = res;
>>> +
>>> + scmi_release_protocol(dres->handle, dres->protocol_id);
>>> +}
>>> +
>>> +/**
>>> + * scmi_devm_get_protocol_ops - Devres managed get protocol operations
>>> + * @sdev: A reference to an scmi_device whose embedded struct device is to
>>> + * be used for devres accounting.
>>> + * @protocol_id: The protocol being requested.
>>> + * @ph: A pointer reference used to pass back the associated protocol handle.
>>> + *
>>> + * Get hold of a protocol accounting for its usage, eventually triggering its
>>> + * initialization, and returning the protocol specific operations and related
>>> + * protocol handle which will be used as first argument in most of the
>>> + * protocols operations methods.
>>> + * Being a devres based managed method, protocol hold will be automatically
>>> + * released, and possibly de-initialized on last user, once the SCMI driver
>>> + * owning the scmi_device is unbound from it.
>>> + *
>>> + * Return: A reference to the requested protocol operations or error.
>>> + * Must be checked for errors by caller.
>>> + */
>>> +static const void __must_check *
>>> +scmi_devm_get_protocol_ops(struct scmi_device *sdev, u8 protocol_id,
>>> + struct scmi_protocol_handle **ph)
>>> +{
>>> + struct scmi_protocol_instance *pi;
>>> + struct scmi_protocol_devres *dres;
>>> + struct scmi_handle *handle = sdev->handle;
>>> +
>>> + if (!ph)
>>> + return ERR_PTR(-EINVAL);
>>> +
>>> + dres = devres_alloc(scmi_devm_release_protocol,
>>> + sizeof(*dres), GFP_KERNEL);
>>> + if (!dres)
>>> + return ERR_PTR(-ENOMEM);
>>> +
>>> + pi = scmi_get_protocol_instance(handle, protocol_id);
>>> + if (IS_ERR(pi)) {
>>> + devres_free(dres);
>>> + return pi;
>>> + }
>>> +
>>> + dres->handle = handle;
>>> + dres->protocol_id = protocol_id;
>>> + devres_add(&sdev->dev, dres);
>>> +
>>> + *ph = &pi->ph;
>>> +
>>> + return pi->proto->ops;
>>> +}
>>> +
>>> +static int scmi_devm_protocol_match(struct device *dev, void *res, void *data)
>>> +{
>>> + struct scmi_protocol_devres *dres = res;
>>> +
>>> + if (WARN_ON(!dres || !data))
>>> + return 0;
>>> +
>>> + return dres->protocol_id == *((u8 *)data);
>>> +}
>>> +
>>> +/**
>>> + * scmi_devm_put_protocol_ops - Devres managed put protocol operations
>>> + * @sdev: A reference to an scmi_device whose embedded struct device is to
>>> + * be used for devres accounting.
>>> + * @protocol_id: The protocol being requested.
>>> + *
>>> + * Explicitly release a protocol hold previously obtained calling the above
>>> + * @scmi_devm_get_protocol_ops.
>>> + */
>>> +static void scmi_devm_put_protocol_ops(struct scmi_device *sdev, u8 protocol_id)
>>> +{
>>> + int ret;
>>> +
>>> + ret = devres_release(&sdev->dev, scmi_devm_release_protocol,
>>> + scmi_devm_protocol_match, &protocol_id);
>>> + WARN_ON(ret);
>>> +}
>>> +
>>> /**
>>> * scmi_handle_get() - Get the SCMI handle for a device
>>> *
>>> @@ -1004,6 +1126,10 @@ static int scmi_probe(struct platform_device *pdev)
>>> handle = &info->handle;
>>> handle->dev = info->dev;
>>> handle->version = &info->version;
>>> + handle->devm_get_ops = scmi_devm_get_protocol_ops;
>>> + handle->devm_put_ops = scmi_devm_put_protocol_ops;
>>> + handle->get_ops = scmi_get_protocol_operations;
>>> + handle->put_ops = scmi_release_protocol;
>>
>> Why do you need a dev_res version and a non dev_res version? I checked
>> patch 6 where you convert the drivers to use these hooks and all of them
>> are using the dev res apis.
>>
>
> Yes indeed, I wanted to drop the non devm_ version, but I was not sure
> if for completeness I should have instead not provided...So I left it
> to have it discussed on the list...I was hoping to be told to remove
> those non devres :D
>
> Also because in fact any current or future SCMI driver (that are the only
> possible users of this interface) will certainly have an scmi_dev to use
> with devm_() methods.
>
> Probably the same is true for notify_ops, I could stick with the new
> devres managed versions.
I think you should drop it, unless any one else has issues not having it.
--
Warm Regards
Thara
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