From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Wed, 9 May 2018 14:38:32 +0100 Subject: [PATCH 1/4] amba: Export amba_bustype In-Reply-To: <20180508140628.f30774c70c4c481bff3f8000@arm.com> References: <20180508140628.f30774c70c4c481bff3f8000@arm.com> Message-ID: <8c2648ec-1379-fb2a-35d2-b3fa8fc9f063@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Kim, On 08/05/18 20:06, Kim Phillips wrote: > This patch is provided in the context of allowing the Coresight driver > subsystem to be loaded as modules. Coresight uses amba_bus in its call > to bus_find_device() in of_coresight_get_endpoint_device() when > searching for a configurable endpoint device. This patch allows > Coresight to reference amba_bustype when built as a module. > > Cc: Mathieu Poirier > Cc: Alex Williamson > Cc: Eric Auger > Cc: Russell King > Cc: Greg Kroah-Hartman > Cc: Todd Kjos > Cc: Geert Uytterhoeven > Cc: Thierry Reding > Cc: Robin Murphy > Signed-off-by: Kim Phillips > --- > There was a prior patch submitted by Alex W. here: > > https://lkml.org/lkml/2017/6/19/811 > > But I can't tell its fate - presume simply delayed? > > Coresight uses amba_bus in its call to bus_find_device() here: > > https://lxr.missinglinkelectronics.com/linux/drivers/hwtracing/coresight/of_coresight.c#L51 > > Grepping for bus_type and EXPORT shows other busses exporting their > type, so I don't think this is the wrong approach. If, OTOH, Coresight > needs to do something differently, please comment. Exposing raw bus_types is pretty ugly, but it is indeed the status quo, so this probably is the reasonable thing to do. I suppose an amba_bus equivalent of of_find_device_by_node() could be implemented, but for only a single potential user that doesn't seem particularly worthwhile, since unless some massive shake-up of how buses work comes along the bus_type will inevitably end up being exported for other reasons anyway. So, in the context of this series; Reviewed-by: Robin Murphy However, as a wild idea for sidestepping the issue completely (or at least keeping it within the CoreSight framework), at first glance it appears something like the below might be feasible, although I may well be missing some obvious reason why not. Thanks, Robin. ----->8----- diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c index 7c375443ede6..2c3fdc9b63e6 100644 --- a/drivers/hwtracing/coresight/of_coresight.c +++ b/drivers/hwtracing/coresight/of_coresight.c @@ -27,28 +27,13 @@ static int of_dev_node_match(struct device *dev, void *data) { - return dev->of_node == data; + return dev->parent->of_node == data; } static struct device * of_coresight_get_endpoint_device(struct device_node *endpoint) { - struct device *dev = NULL; - - /* - * If we have a non-configurable replicator, it will be found on the - * platform bus. - */ - dev = bus_find_device(&platform_bus_type, NULL, - endpoint, of_dev_node_match); - if (dev) - return dev; - - /* - * We have a configurable component - circle through the AMBA bus - * looking for the device that matches the endpoint node. - */ - return bus_find_device(&amba_bustype, NULL, + return bus_find_device(&coresight_bustype, NULL, endpoint, of_dev_node_match); }