On 4/21/21 7:40 PM, Mathieu Poirier wrote:
> Good day Arnaud,
>
> On Tue, Apr 13, 2021 at 03:44:56PM +0200, Arnaud Pouliquen wrote:
>> A rpmsg char device allows to probe the endpoint device on a remote name
>> service announcement.
>>
>> With this patch the /dev/rpmsgX interface is created either by a user
>> application or by the remote firmware.
>>
>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
>>
>> ---
>> update from V1:
>> - add missing unregister_rpmsg_driver call on module exit.
>>
>> ---
>> drivers/rpmsg/rpmsg_char.c | 59 +++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 58 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
>> index a64249d83172..4606787b7011 100644
>> --- a/drivers/rpmsg/rpmsg_char.c
>> +++ b/drivers/rpmsg/rpmsg_char.c
>> @@ -26,6 +26,8 @@
>> #include "rpmsg_char.h"
>> #include "rpmsg_internal.h"
>>
>> +#define RPMSG_CHAR_DEVNAME "rpmsg-raw"
>> +
>
> Why not simply call it rpmsg-char?
I would avoid to link the rpmsg name service to the Linux Kernel device.
>
>> static dev_t rpmsg_major;
>>
>> static DEFINE_IDA(rpmsg_ept_ida);
>> @@ -403,13 +405,67 @@ int rpmsg_chrdev_create_eptdev(struct rpmsg_device *rpdev, struct device *parent
>> }
>> EXPORT_SYMBOL(rpmsg_chrdev_create_eptdev);
>>
>> +static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
>> +{
>> + struct rpmsg_channel_info chinfo;
>> + struct rpmsg_eptdev *eptdev;
>> +
>> + if (!rpdev->ept)
>> + return -EINVAL;
>> +
>> + memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
>> + chinfo.src = rpdev->src;
>> + chinfo.dst = rpdev->dst;
>> +
>> + eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo, NULL);
>> + if (IS_ERR(eptdev))
>> + return PTR_ERR(eptdev);
>> +
>> + /* Set the private field of the default endpoint to retrieve context on callback. */
>> + rpdev->ept->priv = eptdev;
>
> This is already done in rpmsg_create_ept() when rpmsg_eptdev_open() is called.
>
>> +
>> + return 0;
>> +}
>> +
>> +static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
>> +{
>> + int ret;
>> +
>> + ret = device_for_each_child(&rpdev->dev, NULL, rpmsg_chrdev_destroy_eptdev);
>> + if (ret)
>> + dev_warn(&rpdev->dev, "failed to destroy endpoints: %d\n", ret);
>> +}
>> +
>> +static struct rpmsg_device_id rpmsg_chrdev_id_table[] = {
>> + { .name = RPMSG_CHAR_DEVNAME },
>> + { },
>> +};
>> +
>> +static struct rpmsg_driver rpmsg_chrdev_driver = {
>> + .probe = rpmsg_chrdev_probe,
>> + .remove = rpmsg_chrdev_remove,
>> + .id_table = rpmsg_chrdev_id_table,
>> + .callback = rpmsg_ept_cb,
>
> Not sure why we need a callback associated to this driver when
> rpmsg_eptdev_open() already creates and rpmsg_endpoint. To me the only thing
> having a callback provides is the association between the rpmsg_device and the
> rpmsg_endpoint[1] that happens in rpmsg_dev_probe(). The QC folks already do
> this association in their platform code[2]. Since this is not done in
> __rpmsg_create_ept() a check for rpdev->ept == NULL could be done in
> rpmsg_eptdev_open() and do the assignment there.
>
> [1]. https://elixir.bootlin.com/linux/v5.12-rc6/source/drivers/rpmsg/rpmsg_core.c#L513
> [2]. https://elixir.bootlin.com/linux/v5.12-rc6/source/drivers/rpmsg/qcom_glink_native.c#L1623
>
That's a good point! When I started the redesign, I faced some issues with the
approach you propose. But as I can not remember the reason and because the code
has evolved, i need to re-think about this.
Thanks,
Arnaud
>> + .drv = {
>> + .name = "rpmsg_chrdev",
>> + },
>> +};
>> +
>> static int rpmsg_chrdev_init(void)
>> {
>> int ret;
>>
>> ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg_char");
>> - if (ret < 0)
>> + if (ret < 0) {
>> pr_err("rpmsg: failed to allocate char dev region\n");
>> + return ret;
>> + }
>> +
>> + ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
>> + if (ret < 0) {
>> + pr_err("rpmsg: failed to register rpmsg raw driver\n");
>> + unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
>> + }
>>
>> return ret;
>> }
>> @@ -417,6 +473,7 @@ postcore_initcall(rpmsg_chrdev_init);
>>
>> static void rpmsg_chrdev_exit(void)
>> {
>> + unregister_rpmsg_driver(&rpmsg_chrdev_driver);
>> unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
>> }
>> module_exit(rpmsg_chrdev_exit);
>> --
>> 2.17.1
>>
