Re: [PATCH v4 03/37] firmware: arm_scmi: introduce devres get/put protocols operations
From: Thara Gopinath
Date: Thu Jan 07 2021 - 09:29:22 EST
On 1/6/21 3:15 PM, Cristian Marussi wrote:
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@xxxxxxx>
---
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 757a826e3cef..2fd2fffb4024 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
@@ -593,6 +595,9 @@ 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)
@@ -618,6 +623,12 @@ 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);
These names are misleading. The devm_get_ops does two things. One
populate the scmi_protocol_handle, second return the protocol ops.
Either split this into two separate functions or rename it into
something like devm_get_protocol (or something better). Similar comment
for devm_put_ops as there is no releasing of ops happening here per say.
Also I am still not convinced that protocol_instance should be hidden
from the client drivers. But if everyone else is aligned towards this
approach, I am fine.
+
const struct scmi_notify_ops *notify_ops;
/* for protocol internal use */
void *perf_priv;
--
Warm Regards
Thara