Hi Suman, Apologies for replying to a subthread, due to an earlier mistake on my part I don't have the original to hand. On Fri, Sep 27, 2013 at 05:04:22PM +0100, Kumar Gala wrote: > > On Sep 17, 2013, at 2:30 PM, Suman Anna wrote: > > > All the platform-specific hwlock driver implementations need the > > number of locks and the associated base id for registering the > > locks present within a hwspinlock device with the driver core. > > These two variables are represented by 'hwlock-num-locks' and > > 'hwlock-base-id' properties. The documentation and OF helpers to > > retrieve these common properties have been added to the driver core. > > > > Signed-off-by: Suman Anna <s-anna@xxxxxx> > > --- > > .../devicetree/bindings/hwlock/hwlock.txt | 26 +++++++++ > > drivers/hwspinlock/hwspinlock_core.c | 61 +++++++++++++++++++++- > > include/linux/hwspinlock.h | 11 ++-- > > 3 files changed, 93 insertions(+), 5 deletions(-) > > create mode 100644 Documentation/devicetree/bindings/hwlock/hwlock.txt > > > > diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt > > new file mode 100644 > > index 0000000..789930e > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt > > @@ -0,0 +1,26 @@ > > +Generic hwlock bindings > > +======================= > > + > > +Generic bindings that are common to all the hwlock platform specific driver > > +implementations, the retrieved values are used for registering the device > > +specific parameters with the hwspinlock core. > > + > > +The validity and need of these common properties may vary from one driver > > +implementation to another. Look through the individual hwlock driver > > +binding documentations for identifying which are mandatory and which are > > +optional for that specific driver. > > + > > +Common properties: > > +- hwlock-base-id: Base Id for the locks for a particular hwlock device. > > + This property is used for representing a set of locks > > + present in a hwlock device with a unique base id in > > + the driver core. This property is mandatory ONLY if a > > + SoC has several hwlock devices. > > + > > + See documentation on struct hwspinlock_pdata in > > + linux/hwspinlock.h for more details. I don't like this, as it seems to be encoding a Linux implementation detail (the ID of the lock, which means that we have to have a numeric representation of each hwlock) in the device tree. I don't see why the ID within Linux should be a concern of the device tree binding. I think that whatever internal identifier we have in Linux (be it an integer or struct) should be allocated by Linux. If a driver needs to request specific hwlocks, then we should have a phandle + args representation for referring to a specific hwlock that bidnings can use, and some code for parsing that and returning a Linux-internal identifier/struct as we do with interrupts and clocks. > > + > > +- hwlock-num-locks: Number of locks present in a hwlock device. This > > + property is needed on hwlock devices, where the number > > + of supported locks within a hwlock device cannot be > > + read from a register. Hmm... this seems generic, but it doesn't allow for sparse ID spaces on the hwlock module. It should probably be common for the moment, but if we encounter a hwlock module with a sparse ID space, we'll need to come up with a way of handling sparse IDs (that might be device-specific). > > diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c > > index 461a0d7..aec32e7 100644 > > --- a/drivers/hwspinlock/hwspinlock_core.c > > +++ b/drivers/hwspinlock/hwspinlock_core.c > > @@ -1,7 +1,7 @@ > > /* > > * Hardware spinlock framework > > * > > - * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com > > + * Copyright (C) 2010-2013 Texas Instruments Incorporated - http://www.ti.com > > * > > * Contact: Ohad Ben-Cohen <ohad@xxxxxxxxxx> > > * > > @@ -27,6 +27,7 @@ > > #include <linux/hwspinlock.h> > > #include <linux/pm_runtime.h> > > #include <linux/mutex.h> > > +#include <linux/of.h> > > > > #include "hwspinlock_internal.h" > > > > @@ -308,6 +309,64 @@ out: > > } > > > > /** > > + * of_hwspin_lock_get_base_id() - OF helper to retrieve base id > > + * @dn: device node pointer > > + * > > + * This is an OF helper function that can be called by the underlying > > + * platform-specific implementations, to retrieve the base id for the > > + * set of locks present within a hwspinlock device instance. > > + * > > + * Returns the base id value on success, -ENODEV on generic failure or > > + * an appropriate error code as returned by the OF layer > > + */ > > +int of_hwspin_lock_get_base_id(struct device_node *dn) > > +{ > > + unsigned int val; > > + int ret = -ENODEV; > > + > > +#ifdef CONFIG_OF > > + if (!dn) > > + return -ENODEV; > > Checking !dn is done in of_property_read_u32, so you don't need to duplicate > > > + > > + ret = of_property_read_u32(dn, "hwlock-base-id", &val); > > + if (!ret) > > + ret = val; > > +#endif Do we need the CONFIG_OF check? of_property_read_u32 is defined to return -ENOSYS if CONFIG_OF isn't defined. Or would that confuse a higher layer? Similarly elsewhere in the file. Cheers, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
