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    Subject[PATCH v3 03/37] firmware: arm_scmi: introduce devres get/put protocols operations
    Date
    Expose to the SCMI drivers a new devres managed common protocols API based
    on generic get/put methods and protocol handles.

    All drivers still keep using the old API, no functional change.

    Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
    ---
    drivers/firmware/arm_scmi/driver.c | 92 ++++++++++++++++++++++++++++++
    include/linux/scmi_protocol.h | 11 ++++
    2 files changed, 103 insertions(+)

    diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
    index 10fe9aacae1b..fbc3ba1b69f6 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>
    @@ -732,6 +733,95 @@ 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
    *
    @@ -986,6 +1076,8 @@ 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;

    ret = scmi_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
    if (ret)
    diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
    index 48393264397f..b9bdb3f1d562 100644
    --- a/include/linux/scmi_protocol.h
    +++ b/include/linux/scmi_protocol.h
    @@ -57,6 +57,8 @@ struct scmi_clock_info {
    };

    struct scmi_handle;
    +struct scmi_device;
    +struct scmi_protocol_handle;

    /**
    * struct scmi_clk_ops - represents the various operations provided
    @@ -592,6 +594,9 @@ struct scmi_notify_ops {
    * @sensor_ops: pointer to set of sensor protocol operations
    * @reset_ops: pointer to set of reset protocol operations
    * @voltage_ops: pointer to set of voltage protocol operations
    + * @devm_get_ops: devres managed method to acquire a protocol and get specific
    + * operations and a dedicated protocol handler
    + * @devm_put_ops: devres managed method to release a protocol
    * @notify_ops: pointer to set of notifications related operations
    * @perf_priv: pointer to private data structure specific to performance
    * protocol(for internal use only)
    @@ -617,6 +622,12 @@ struct scmi_handle {
    const struct scmi_sensor_ops *sensor_ops;
    const struct scmi_reset_ops *reset_ops;
    const struct scmi_voltage_ops *voltage_ops;
    +
    + const void __must_check *
    + (*devm_get_ops)(struct scmi_device *sdev, u8 proto,
    + struct scmi_protocol_handle **ph);
    + void (*devm_put_ops)(struct scmi_device *sdev, u8 proto);
    +
    const struct scmi_notify_ops *notify_ops;
    /* for protocol internal use */
    void *perf_priv;
    --
    2.17.1
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