On Thu, 25 Mar 2010 14:17:41 +0100 Giel van Schijndel <me@xxxxxxxxx> wrote: > From: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> > > This patch was originally written by Alan Cox [1]. I only updated it to > apply correctly to Linus' current tree and changed IORESOURCE_MUXED's > value from 0x00200000 to 0x00400000 because the former has already been > taken in use since. > > [1] https://patchwork.kernel.org/patch/32397/ > > Patch after this line: > ======================================================================== > SuperIO devices share regions and use lock/unlock operations to chip > select. We therefore need to be able to request a resource and wait for > it to be freed by whichever other SuperIO device currently hogs it. > Right now you have to poll which is horrible. > > Add a MUXED field to IO port resources. If the MUXED field is set on the > resource and on the request (via request_muxed_region) then we block > until the previous owner of the muxed resource releases their region. > > This allows us to implement proper resource sharing and locking for > superio chips using code of the form > > enable_my_superio_dev() { > request_muxed_region(0x44, 0x02, "superio:watchdog"); > outb() ..sequence to enable chip > } > > disable_my_superio_dev() { > outb() .. sequence of disable chip > release_region(0x44, 0x02); > } > > Signed-off-by: Giel van Schijndel <me@xxxxxxxxx> > --- > include/linux/ioport.h | 4 +++- > kernel/resource.c | 14 +++++++++++++- > 2 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/include/linux/ioport.h b/include/linux/ioport.h > index 71ab79d..604fd29 100644 > --- a/include/linux/ioport.h > +++ b/include/linux/ioport.h > @@ -52,6 +52,7 @@ struct resource_list { > > #define IORESOURCE_MEM_64 0x00100000 > #define IORESOURCE_WINDOW 0x00200000 /* forwarded by bridge */ > +#define IORESOURCE_MUXED 0x00400000 /* Resource is software muxed */ > > #define IORESOURCE_EXCLUSIVE 0x08000000 /* Userland may not map this resource */ > #define IORESOURCE_DISABLED 0x10000000 > @@ -141,7 +142,8 @@ static inline unsigned long resource_type(const struct resource *res) > } > > /* Convenience shorthand with allocation */ > -#define request_region(start,n,name) __request_region(&ioport_resource, (start), (n), (name), 0) > +#define request_region(start,n,name) __request_region(&ioport_resource, (start), (n), (name), 0) > +#define request_muxed_region(start,n,name) __request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED) > #define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl) > #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name), 0) > #define request_mem_region_exclusive(start,n,name) \ > diff --git a/kernel/resource.c b/kernel/resource.c > index 2d5be5d..1484180 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -651,6 +651,8 @@ resource_size_t resource_alignment(struct resource *res) > * release_region releases a matching busy region. > */ > > +static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait); > + > /** > * __request_region - create a new busy resource region > * @parent: parent resource descriptor > @@ -663,6 +665,7 @@ struct resource * __request_region(struct resource *parent, > resource_size_t start, resource_size_t n, > const char *name, int flags) > { > + DECLARE_WAITQUEUE(wait, current); > struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL); > > if (!res) > @@ -687,7 +690,14 @@ struct resource * __request_region(struct resource *parent, > if (!(conflict->flags & IORESOURCE_BUSY)) > continue; > } > - > + if (conflict->flags & flags & IORESOURCE_MUXED) { > + add_wait_queue(&muxed_resource_wait, &wait); > + write_unlock(&resource_lock); needs a set_current_state(TASK_UNINTERRUPTIBLE); here (error from my original test patch that I noticed re-reviewing it) _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
