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    SubjectRe: [PATCH v6 37/37] firmware: arm_scmi: add dynamic scmi devices creation
    Hi Cristian,

    Sorry for the delay.

    On Tue, Feb 02, 2021 at 10:15:55PM +0000, Cristian Marussi wrote:
    > Having added the support for SCMI protocols as modules in order to let
    > vendors extend the SCMI core with their own additions it seems odd to
    > then force SCMI drivers built on top to use a static device table to
    > declare their devices since this way any new SCMI drivers addition
    > would need the core SCMI device table to be updated too.
    >
    > Remove the static core device table and let SCMI drivers to simply declare
    > which device/protocol pair they need at initialization time: the core will
    > then take care to generate such devices dynamically during platform
    > initialization or at module loading time, as long as the requested
    > underlying protocol is defined in the DT.
    >
    > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
    > ---
    > v4 --> v5
    > - using klist instead of custom lists
    > v3 --> v4
    > - add a few comments
    > ---
    > drivers/firmware/arm_scmi/bus.c | 30 +++
    > drivers/firmware/arm_scmi/common.h | 5 +
    > drivers/firmware/arm_scmi/driver.c | 309 +++++++++++++++++++++++++----
    > 3 files changed, 310 insertions(+), 34 deletions(-)
    >
    > diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
    > index 88e5057f4e85..88149a46e6d9 100644
    > --- a/drivers/firmware/arm_scmi/bus.c
    > +++ b/drivers/firmware/arm_scmi/bus.c
    > @@ -51,6 +51,31 @@ static int scmi_dev_match(struct device *dev, struct device_driver *drv)
    > return 0;
    > }
    >
    > +static int scmi_match_by_id_table(struct device *dev, void *data)
    > +{
    > + struct scmi_device *sdev = to_scmi_dev(dev);
    > + struct scmi_device_id *id_table = data;
    > +
    > + return sdev->protocol_id == id_table->protocol_id &&
    > + !strcmp(sdev->name, id_table->name);
    > +}
    > +
    > +struct scmi_device *scmi_find_child_dev(struct device *parent,
    > + int prot_id, const char *name)
    > +{
    > + struct scmi_device_id id_table;
    > + struct device *dev;
    > +
    > + id_table.protocol_id = prot_id;
    > + id_table.name = name;
    > +
    > + dev = device_find_child(parent, &id_table, scmi_match_by_id_table);
    > + if (!dev)
    > + return NULL;
    > +
    > + return to_scmi_dev(dev);
    > +}
    > +
    > const struct scmi_protocol *scmi_get_protocol(int protocol_id)
    > {
    > const struct scmi_protocol *proto;
    > @@ -114,6 +139,10 @@ int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
    > {
    > int retval;
    >
    > + retval = scmi_request_protocol_device(driver->id_table);
    > + if (retval)
    > + return retval;
    > +
    > driver->driver.bus = &scmi_bus_type;
    > driver->driver.name = driver->name;
    > driver->driver.owner = owner;
    > @@ -130,6 +159,7 @@ EXPORT_SYMBOL_GPL(scmi_driver_register);
    > void scmi_driver_unregister(struct scmi_driver *driver)
    > {
    > driver_unregister(&driver->driver);
    > + scmi_unrequest_protocol_device(driver->id_table);
    > }
    > EXPORT_SYMBOL_GPL(scmi_driver_unregister);
    >
    > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
    > index 1e2046c61d43..9a0519db4865 100644
    > --- a/drivers/firmware/arm_scmi/common.h
    > +++ b/drivers/firmware/arm_scmi/common.h
    > @@ -307,6 +307,11 @@ struct scmi_transport_ops {
    > bool (*poll_done)(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer);
    > };
    >
    > +int scmi_request_protocol_device(const struct scmi_device_id *id_table);
    > +void scmi_unrequest_protocol_device(const struct scmi_device_id *id_table);

    Sorry for being pedantic, I don't like these names. I would prefer
    something like scmi_protocol_device_{create,destroy/delete}_request.
    The action the function does needs to be at the end of the function name.
    Atleast that is something I follow. I haven't checked all the previous
    patches, just this function made to look at both the name style and the
    name itself.


    > +struct scmi_device *scmi_find_child_dev(struct device *parent,
    > + int prot_id, const char *name);
    > +

    scmi_child_dev_find based on what I mentioned above. Please change all
    other non-static functions even if I have not mentioned. Try to cover
    all the new functions introduced in this series, existing ones we can
    take up later.

    > /**
    > * struct scmi_desc - Description of SoC integration
    > *
    > diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
    > index dcdfd94b47f7..9fc979e3b16f 100644
    > --- a/drivers/firmware/arm_scmi/driver.c
    > +++ b/drivers/firmware/arm_scmi/driver.c
    > @@ -21,6 +21,7 @@
    > #include <linux/io.h>
    > #include <linux/kernel.h>
    > #include <linux/ktime.h>
    > +#include <linux/list.h>
    > #include <linux/module.h>
    > #include <linux/of_address.h>
    > #include <linux/of_device.h>
    > @@ -56,6 +57,14 @@ static DEFINE_MUTEX(scmi_list_mutex);
    > /* Track the unique id for the transfers for debug & profiling purpose */
    > static atomic_t transfer_last_id;
    >
    > +static DEFINE_IDR(scmi_requested_devices);
    > +static DEFINE_MUTEX(scmi_requested_devices_mtx);
    > +
    > +struct scmi_requested_dev {
    > + const struct scmi_device_id *id_table;
    > + struct list_head node;
    > +};
    > +
    > /**
    > * struct scmi_xfers_info - Structure to manage transfer information
    > *
    > @@ -113,6 +122,8 @@ struct scmi_protocol_instance {
    > * @protocols_mtx: A mutex to protect protocols instances initialization.
    > * @protocols_imp: List of protocols implemented, currently maximum of
    > * MAX_PROTOCOLS_IMP elements allocated by the base protocol
    > + * @active_protocols: IDR storing device_nodes for protocols actually defined
    > + * in the DT and confirmed as implemented by fw.
    > * @notify_priv: Pointer to private data structure specific to notifications.
    > * @node: List head
    > * @users: Number of users of this instance
    > @@ -130,6 +141,7 @@ struct scmi_info {
    > /* Ensure mutual exclusive access to protocols instance array */
    > struct mutex protocols_mtx;
    > u8 *protocols_imp;
    > + struct idr active_protocols;
    > void *notify_priv;
    > struct list_head node;
    > int users;
    > @@ -936,6 +948,13 @@ static void scmi_devm_put_protocol(struct scmi_device *sdev, u8 protocol_id)
    > WARN_ON(ret);
    > }
    >
    > +static inline
    > +struct scmi_handle *scmi_handle_get_from_info(struct scmi_info *info)
    > +{
    > + info->users++;

    Doesn't it race with anything ? I have already forgotten how this is used
    and in what context this gets called.

    > + return &info->handle;
    > +}
    > +
    > /**
    > * scmi_handle_get() - Get the SCMI handle for a device
    > *
    > @@ -957,8 +976,7 @@ struct scmi_handle *scmi_handle_get(struct device *dev)
    > list_for_each(p, &scmi_list) {
    > info = list_entry(p, struct scmi_info, node);
    > if (dev->parent == info->dev) {
    > - handle = &info->handle;
    > - info->users++;
    > + handle = scmi_handle_get_from_info(info);

    Ah here it is. Any particular reasons for moving it to separate function ?

    --
    Regards,
    Sudeep

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