Below are the links on multi master bus arbitration where it has been discussing. http://comments.gmane.org/gmane.linux.kernel/1410276 http://www.kernelhub.org/?msg=179505&p=2 On Mon, Feb 4, 2013 at 2:33 PM, Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxx> wrote: > This RFC patch is w.r.t multimaster bus arbitration which is already > being discussing in the mainline. > This patch provides hooks for the i2c multimaster bus arbitration > and to have the arbitration parameters. > > Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxxxx> > --- > drivers/i2c/i2c-core.c | 13 ++++++++++++- > include/linux/i2c.h | 12 ++++++++++++ > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index e388590..ed89fc8 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -1408,18 +1408,29 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) > (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : ""); > } > #endif > + if (adap->mm_arbit_algo) { > + ret = adap->mm_arbit_algo->i2c_mm_bus_get(adap); > + if (ret) > + /* I2C bus under control of another master. */ > + return -EAGAIN; > + } > > if (in_atomic() || irqs_disabled()) { > ret = i2c_trylock_adapter(adap); > - if (!ret) > + if (!ret && adap->mm_arbit_algo) { > + adap->mm_arbit_algo->i2c_mm_bus_release(adap); > + > /* I2C activity is ongoing. */ > return -EAGAIN; > + } > } else { > i2c_lock_adapter(adap); > } > > ret = __i2c_transfer(adap, msgs, num); > i2c_unlock_adapter(adap); > + if (adap->mm_arbit_algo) > + adap->mm_arbit_algo->i2c_mm_bus_release(adap); > > return ret; > } else { > diff --git a/include/linux/i2c.h b/include/linux/i2c.h > index d0c4db7..61fbfe3 100644 > --- a/include/linux/i2c.h > +++ b/include/linux/i2c.h > @@ -371,6 +371,17 @@ struct i2c_algorithm { > }; > > /* > + *This struct provides hooks for i2c multi-master arbitration needs. > + */ > +struct i2c_mm_arbitration { > + void *arbitration_data; > + > + /* Should return 0 if mastership could be successfully established */ > + int (*i2c_mm_bus_get)(struct i2c_adapter *adap); > + void (*i2c_mm_bus_release)(struct i2c_adapter *adap); > +}; > + > +/* > * i2c_adapter is the structure used to identify a physical i2c bus along > * with the access algorithms necessary to access it. > */ > @@ -393,6 +404,7 @@ struct i2c_adapter { > > struct mutex userspace_clients_lock; > struct list_head userspace_clients; > + struct i2c_mm_arbitration *mm_arbit_algo; > }; > #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev) > > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
