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SubjectRe: [PATCH v2 29/36] coresight: Use fwnode handle instead of device names
On Mon, Apr 15, 2019 at 05:04:12PM +0100, Suzuki K Poulose wrote:
> We rely on the device names to find a CoreSight device on the
> coresight bus. The device name however is obtained from the platform,
> which is bound to the real platform/amba device. As we are about
> to use different naming scheme for the coresight devices, we can't
> rely on the platform device name to find the corresponding
> coresight device. Instead we use the platform agnostic
> "fwnode handle" of the parent device to find the devices.
> We also reuse the same fwnode as the parent for the Coresight
> device we create.
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> drivers/hwtracing/coresight/coresight-platform.c | 12 +++++--
> drivers/hwtracing/coresight/coresight-priv.h | 4 +--
> drivers/hwtracing/coresight/coresight.c | 42 +++++++++++++++++++-----
> include/linux/coresight.h | 4 +--
> 4 files changed, 46 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> index 318a6ff..c9a59fb 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -214,9 +214,15 @@ static int of_coresight_parse_endpoint(struct device *dev,
> }
>
> conn->outport = endpoint.port;
> - conn->child_name = devm_kstrdup(dev,
> - dev_name(rdev),
> - GFP_KERNEL);
> + /*
> + * Hold the refcount to the target device. This could be
> + * released via:
> + * 1) coresight_release_platform_data() if the probe fails or
> + * this device is unregistered.
> + * 2) While removing the target device via
> + * coresight_remove_match()
> + */

Many thanks for the documentation - not only does it help me but it also makes
it easier for other people to contribute to the subsystem.

> + conn->child_fwnode = fwnode_handle_get(rdev_fwnode);
> conn->child_port = rendpoint.port;
> /* Connection record updated */
> ret = 1;
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index c216421..61d7f9f 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -200,8 +200,6 @@ static inline void *coresight_get_uci_data(const struct amba_id *id)
> return 0;
> }
>
> -static inline void
> -coresight_release_platform_data(struct coresight_platform_data *pdata)
> -{}
> +void coresight_release_platform_data(struct coresight_platform_data *pdata);

Now that we have fixed of_get_coresight_platform_data() I think patch 26 should
be rolled into this one. That way everything related to
coresight_release_platform_data() is done in the same patch and the function
doesn't have to be modified twice.

>
> #endif
> diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
> index 82fb411..5169ce1 100644
> --- a/drivers/hwtracing/coresight/coresight.c
> +++ b/drivers/hwtracing/coresight/coresight.c
> @@ -976,6 +976,7 @@ static void coresight_device_release(struct device *dev)
> {
> struct coresight_device *csdev = to_coresight_device(dev);
>
> + fwnode_handle_put(csdev->dev.fwnode);
> kfree(csdev->refcnt);
> kfree(csdev);
> }
> @@ -1007,13 +1008,11 @@ static int coresight_orphan_match(struct device *dev, void *data)
> /* We have found at least one orphan connection */
> if (conn->child_dev == NULL) {
> /* Does it match this newly added device? */
> - if (conn->child_name &&
> - !strcmp(dev_name(&csdev->dev), conn->child_name)) {
> + if (conn->child_fwnode == csdev->dev.fwnode)
> conn->child_dev = csdev;
> - } else {
> + else
> /* This component still has an orphan */
> still_orphan = true;
> - }
> }
> }
>
> @@ -1045,9 +1044,9 @@ static void coresight_fixup_device_conns(struct coresight_device *csdev)
> struct coresight_connection *conn = &csdev->pdata->conns[i];
> struct device *dev = NULL;
>
> - if (conn->child_name)
> - dev = bus_find_device_by_name(&coresight_bustype, NULL,
> - conn->child_name);
> + dev = bus_find_device(&coresight_bustype, NULL,
> + (void *)conn->child_fwnode,
> + device_fwnode_match);
> if (dev) {
> conn->child_dev = to_coresight_device(dev);
> /* and put reference from 'bus_find_device()' */
> @@ -1082,9 +1081,15 @@ static int coresight_remove_match(struct device *dev, void *data)
> if (conn->child_dev == NULL)
> continue;
>
> - if (!strcmp(dev_name(&csdev->dev), conn->child_name)) {
> + if (csdev->dev.fwnode == conn->child_fwnode) {
> iterator->orphan = true;
> conn->child_dev = NULL;
> + /*
> + * Drop the reference to the handle for the remote
> + * device acquired in parsing the connections from
> + * platform data.
> + */
> + fwnode_handle_put(conn->child_fwnode);
> /* No need to continue */
> break;
> }
> @@ -1164,6 +1169,22 @@ static int __init coresight_init(void)
> }
> postcore_initcall(coresight_init);
>
> +/*
> + * coresight_release_platform_data: Release references to the devices connected
> + * to the output port of this device.
> + */
> +void coresight_release_platform_data(struct coresight_platform_data *pdata)
> +{
> + int i;
> +
> + for (i = 0; i < pdata->nr_outport; i++) {
> + if (pdata->conns[i].child_fwnode) {
> + fwnode_handle_put(pdata->conns[i].child_fwnode);
> + pdata->conns[i].child_fwnode = 0;

pdata->conns[i].child_fwnode = NULL;
> +
> + }
> +}
> +
> struct coresight_device *coresight_register(struct coresight_desc *desc)
> {
> int ret;
> @@ -1208,6 +1229,11 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
> csdev->dev.parent = desc->dev;
> csdev->dev.release = coresight_device_release;
> csdev->dev.bus = &coresight_bustype;
> + /*
> + * Hold the reference to our parent device. This will be
> + * dropped only in coresight_device_release().
> + */
> + csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev));
> dev_set_name(&csdev->dev, "%s", desc->name);
>
> ret = device_register(&csdev->dev);
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index 8c10def..188e759 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -126,15 +126,15 @@ struct coresight_desc {
> /**
> * struct coresight_connection - representation of a single connection
> * @outport: a connection's output port number.
> - * @chid_name: remote component's name.
> * @child_port: remote component's port number @output is connected to.
> + * @chid_fwnode: remote component's fwnode handle.
> * @child_dev: a @coresight_device representation of the component
> connected to @outport.
> */
> struct coresight_connection {
> int outport;
> - const char *child_name;
> int child_port;
> + struct fwnode_handle *child_fwnode;
> struct coresight_device *child_dev;
> };
>
> --
> 2.7.4
>

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