[PATCH 2/2] firmware: arm_ffa: Split bus and driver into distinct modules

[Sudeep Holla]

On Tue, May 14, 2024 at 02:54:46PM +0000, Sebastian Ene wrote:
> On Fri, May 10, 2024 at 07:38:11PM +0100, Sudeep Holla wrote:
> > Make the FF-A bus on its own as a distinct module initialized at
> > subsys_initcall level when builtin.
> > 
> > Keep the FF-A driver core stack, together with any configured transport,
> > in a different module initialized as module_init level.
> > 
> > FF-A drivers initialization is now changed to module_init level.
> > 
> > Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> > ---
> >  drivers/firmware/arm_ffa/Makefile |  6 ++++--
> >  drivers/firmware/arm_ffa/bus.c    | 22 ++++++++++++++++------
> >  drivers/firmware/arm_ffa/common.h |  2 --
> >  drivers/firmware/arm_ffa/driver.c | 12 ++----------
> >  4 files changed, 22 insertions(+), 20 deletions(-)
> > 
> > Hi Sebastian,
> > 
> > I reworked the patch I shared with you in private to include handling of
> > the FF-A v1.0 workaround I had removed as a quick hack when I shared the
> > patch. Please check if these couple of patches help you in the initcall
> > order issue you were facing.
> > 
> > Regards,
> > Sudeep
> 
> Hello Sudeep,
> 
> 
> Thank for sharing the patch. I gave it a spin with pKVM and OPTee under
> Qemu and it works well. Having the bus driver initialize separately is a
> good ideea.
>

Thanks for the review and testing.

> > 
> > diff --git a/drivers/firmware/arm_ffa/Makefile b/drivers/firmware/arm_ffa/Makefile
> > index 9d9f37523200..168990a7e792 100644
> > --- a/drivers/firmware/arm_ffa/Makefile
> > +++ b/drivers/firmware/arm_ffa/Makefile
> > @@ -2,5 +2,7 @@
> >  ffa-bus-y = bus.o
> >  ffa-driver-y = driver.o
> >  ffa-transport-$(CONFIG_ARM_FFA_SMCCC) += smccc.o
> > -ffa-module-objs := $(ffa-bus-y) $(ffa-driver-y) $(ffa-transport-y)
> > -obj-$(CONFIG_ARM_FFA_TRANSPORT) = ffa-module.o
> > +ffa-core-objs := $(ffa-bus-y)
> > +ffa-module-objs := $(ffa-driver-y) $(ffa-transport-y)
> > +obj-$(CONFIG_ARM_FFA_TRANSPORT)  = ffa-core.o
> > +obj-$(CONFIG_ARM_FFA_TRANSPORT) += ffa-module.o
> > diff --git a/drivers/firmware/arm_ffa/bus.c b/drivers/firmware/arm_ffa/bus.c
> > index 2f557e90f2eb..0c83931485f6 100644
> > --- a/drivers/firmware/arm_ffa/bus.c
> > +++ b/drivers/firmware/arm_ffa/bus.c
> > @@ -30,12 +30,11 @@ static int ffa_device_match(struct device *dev, struct device_driver *drv)
> >  	while (!uuid_is_null(&id_table->uuid)) {
> >  		/*
> >  		 * FF-A v1.0 doesn't provide discovery of UUIDs, just the
> > -		 * partition IDs, so fetch the partitions IDs for this
> > -		 * id_table UUID and assign the UUID to the device if the
> > -		 * partition ID matches
> > +		 * partition IDs, so match it unconditionally here and handle
> > +		 * it via the installed bus notifier during driver binding.
> >  		 */
> >  		if (uuid_is_null(&ffa_dev->uuid))
> > -			ffa_device_match_uuid(ffa_dev, &id_table->uuid);
> > +			return 1;
> > 
> >  		if (uuid_equal(&ffa_dev->uuid, &id_table->uuid))
> >  			return 1;
> > @@ -50,6 +49,10 @@ static int ffa_device_probe(struct device *dev)
> >  	struct ffa_driver *ffa_drv = to_ffa_driver(dev->driver);
> >  	struct ffa_device *ffa_dev = to_ffa_dev(dev);
> > 
> > +	/* UUID can be still NULL with FF-A v1.0, so just skip probing them */
> > +	if (uuid_is_null(&ffa_dev->uuid))
> > +		return -ENODEV;
> > +
> >  	return ffa_drv->probe(ffa_dev);
> >  }
> > 
> > @@ -232,14 +235,21 @@ void ffa_device_unregister(struct ffa_device *ffa_dev)
> >  }
> >  EXPORT_SYMBOL_GPL(ffa_device_unregister);
> > 
> > -int arm_ffa_bus_init(void)
> > +static int __init arm_ffa_bus_init(void)
> >  {
> >  	return bus_register(&ffa_bus_type);
> >  }
> > +subsys_initcall(arm_ffa_bus_init);
> > 
> > -void arm_ffa_bus_exit(void)
> > +static void __exit arm_ffa_bus_exit(void)
> >  {
> >  	ffa_devices_unregister();
> >  	bus_unregister(&ffa_bus_type);
> >  	ida_destroy(&ffa_bus_id);
> >  }
> > +module_exit(arm_ffa_bus_exit);
> > +
> > +MODULE_ALIAS("ffa-core");
> > +MODULE_AUTHOR("Sudeep Holla <sudeep.holla at arm.com>");
> > +MODULE_DESCRIPTION("ARM FF-A bus");
> > +MODULE_LICENSE("GPL");
> > diff --git a/drivers/firmware/arm_ffa/common.h b/drivers/firmware/arm_ffa/common.h
> > index d6eccf1fd3f6..9c6425a81d0d 100644
> > --- a/drivers/firmware/arm_ffa/common.h
> > +++ b/drivers/firmware/arm_ffa/common.h
> > @@ -14,8 +14,6 @@ typedef struct arm_smccc_1_2_regs ffa_value_t;
> > 
> >  typedef void (ffa_fn)(ffa_value_t, ffa_value_t *);
> > 
> > -int arm_ffa_bus_init(void);
> > -void arm_ffa_bus_exit(void);
> >  bool ffa_device_is_valid(struct ffa_device *ffa_dev);
> >  void ffa_device_match_uuid(struct ffa_device *ffa_dev, const uuid_t *uuid);
> > 
> > diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> > index 159f2106a541..7cdd425c5fc4 100644
> > --- a/drivers/firmware/arm_ffa/driver.c
> > +++ b/drivers/firmware/arm_ffa/driver.c
> > @@ -1603,14 +1603,9 @@ static int __init ffa_init(void)
> >  	if (ret)
> >  		return ret;
> > 
> > -	ret = arm_ffa_bus_init();
> > -	if (ret)
> > -		return ret;
> > -
> >  	drv_info = kzalloc(sizeof(*drv_info), GFP_KERNEL);
> >  	if (!drv_info) {
> > -		ret = -ENOMEM;
> > -		goto ffa_bus_exit;
> > +		return -ENOMEM;
> >  	}
> > 
> >  	ret = ffa_version_check(&drv_info->version);
> > @@ -1671,11 +1666,9 @@ static int __init ffa_init(void)
> >  	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
> >  free_drv_info:
> >  	kfree(drv_info);
> > -ffa_bus_exit:
> > -	arm_ffa_bus_exit();
> >  	return ret;
> >  }
> > -subsys_initcall(ffa_init);
> > +module_init(ffa_init);
> > 
> >  static void __exit ffa_exit(void)
> >  {
> > @@ -1685,7 +1678,6 @@ static void __exit ffa_exit(void)
> >  	free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
> >  	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
> >  	kfree(drv_info);
> > -	arm_ffa_bus_exit();
> >  }
> >  module_exit(ffa_exit);
> > 
> > --
> > 2.43.2
> > 
> 
> Ack, Sebastian

I wasn't sure if that meant

Acked-by: Sebastian Ene <sebastianene at google.com>

So, I didn't add it intentionally in v2. Please ack/review v2 if you are
happy with that.

--
Regards,
Sudeep