remoteproc: maintain a generic child device for each rproc

For each registered rproc, maintain a generic remoteproc device whose
parent is the low level platform-specific device (commonly a pdev, but
it may certainly be any other type of device too).

With this in hand, the resulting device hierarchy might then look like:

omap-rproc.0
 |
 - remoteproc0  <---- new !
    |
    - virtio0
    |
    - virtio1
       |
       - rpmsg0
       |
       - rpmsg1
       |
       - rpmsg2

Where:
- omap-rproc.0 is the low level device that's bound to the
  driver which invokes rproc_register()
- remoteproc0 is the result of this patch, and will be added by the
  remoteproc framework when rproc_register() is invoked
- virtio0 and virtio1 are vdevs that are registered by remoteproc
  when it realizes that they are supported by the firmware
  of the physical remote processor represented by omap-rproc.0
- rpmsg0, rpmsg1 and rpmsg2 are rpmsg devices that represent rpmsg
  channels, and are registerd by the rpmsg bus when it gets notified
  about their existence

Technically, this patch:
- changes 'struct rproc' to contain this generic remoteproc.x device
- creates a new "remoteproc" type, to which this new generic remoteproc.x
  device belong to.
- adds a super simple enumeration method for the indices of the
  remoteproc.x devices
- updates all dev_* messaging to use the generic remoteproc.x device
  instead of the low level platform-specific device
- updates all dma_* allocations to use the parent of remoteproc.x (where
  the platform-specific memory pools, most commonly CMA, are to be found)

Adding this generic device has several merits:
- we can now add remoteproc runtime PM support simply by hooking onto the
  new "remoteproc" type
- all remoteproc log messages will now carry a common name prefix
  instead of having a platform-specific one
- having a device as part of the rproc struct makes it possible to simplify
  refcounting (see subsequent patch)

Thanks to Stephen Boyd <sboyd@codeaurora.org> for suggesting and
discussing these ideas in one of the remoteproc review threads and
to Fernando Guzman Lugo <fernando.lugo@ti.com> for trying them out
with the (upcoming) runtime PM support for remoteproc.

Cc: Fernando Guzman Lugo <fernando.lugo@ti.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index f1ffabb978d3..7f806dcf5278 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -369,7 +369,7 @@ enum rproc_state {
  * @firmware: name of firmware file to be loaded
  * @priv: private data which belongs to the platform-specific rproc module
  * @ops: platform-specific start/stop rproc handlers
- * @dev: underlying device
+ * @dev: virtual device for refcounting and common remoteproc behavior
  * @refcount: refcount of users that have a valid pointer to this rproc
  * @power: refcount of users who need this rproc powered up
  * @state: state of the device
@@ -383,6 +383,7 @@ enum rproc_state {
  * @bootaddr: address of first instruction to boot rproc with (optional)
  * @rvdevs: list of remote virtio devices
  * @notifyids: idr for dynamically assigning rproc-wide unique notify ids
+ * @index: index of this rproc device
  */
 struct rproc {
         struct klist_node node;
@@ -391,7 +392,7 @@ struct rproc {
         const char *firmware;
         void *priv;
         const struct rproc_ops *ops;
-        struct device *dev;
+        struct device dev;
         struct kref refcount;
         atomic_t power;
         unsigned int state;
@@ -405,6 +406,7 @@ struct rproc {
         u32 bootaddr;
         struct list_head rvdevs;
         struct idr notifyids;
+        int index;
 };
 
 /* we currently support only two vrings per rvdev */