firmware: arm_ffa: Make ffa_bus_type const

Now that the driver core can properly handle constant struct bus_type,
move the ffa_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240211-bus_cleanup-firmware2-v1-1-1851c92c7be7@marliere.net
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Emit modalias for FF-A devices

In order to enable libkmod lookups for FF-A device objects to their
corresponding module, add 'modalias' to the base attribute of FF-A
devices.

Tested-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Link: https://lore.kernel.org/r/20231005175640.379631-1-sudeep.holla@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Assign the missing IDR allocation ID to the FFA device

Commit 19b8766459c4 ("firmware: arm_ffa: Fix FFA device names for logical
partitions") added an ID to the FFA device using ida_alloc() and append
the same to "arm-ffa" to make up a unique device name. However it missed
to stash the id value in ffa_dev to help freeing the ID later when the
device is destroyed.

Due to the missing/unassigned ID in FFA device, we get the following
warning when the FF-A device is unregistered.

| ida_free called for id=0 which is not allocated.
| WARNING: CPU: 7 PID: 1 at lib/idr.c:525 ida_free+0x114/0x164
| CPU: 7 PID: 1 Comm: swapper/0 Not tainted 6.6.0-rc4 #209
| pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
| pc : ida_free+0x114/0x164
| lr : ida_free+0x114/0x164
| Call trace:
| ida_free+0x114/0x164
| ffa_release_device+0x24/0x3c
| device_release+0x34/0x8c
| kobject_put+0x94/0xf8
| put_device+0x18/0x24
| klist_devices_put+0x14/0x20
| klist_next+0xc8/0x114
| bus_for_each_dev+0xd8/0x144
| arm_ffa_bus_exit+0x30/0x54
| ffa_init+0x68/0x330
| do_one_initcall+0xdc/0x250
| do_initcall_level+0x8c/0xac
| do_initcalls+0x54/0x94
| do_basic_setup+0x1c/0x28
| kernel_init_freeable+0x104/0x170
| kernel_init+0x20/0x1a0
| ret_from_fork+0x10/0x20

Fix the same by actually assigning the ID in the FFA device this time
for real.

Fixes: 19b8766459c4 ("firmware: arm_ffa: Fix FFA device names for logical partitions")
Link: https://lore.kernel.org/r/20231003085932.3553985-1-sudeep.holla@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Fix FFA device names for logical partitions

Each physical partition can provide multiple services each with UUID.
Each such service can be presented as logical partition with a unique
combination of VM ID and UUID. The number of distinct UUID in a system
will be less than or equal to the number of logical partitions.

However, currently it fails to register more than one logical partition
or service within a physical partition as the device name contains only
VM ID while both VM ID and UUID are maintained in the partition information.
The kernel complains with the below message:

| sysfs: cannot create duplicate filename '/devices/arm-ffa-8001'
| CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc7 #8
| Hardware name: FVP Base RevC (DT)
| Call trace:
| dump_backtrace+0xf8/0x118
| show_stack+0x18/0x24
| dump_stack_lvl+0x50/0x68
| dump_stack+0x18/0x24
| sysfs_create_dir_ns+0xe0/0x13c
| kobject_add_internal+0x220/0x3d4
| kobject_add+0x94/0x100
| device_add+0x144/0x5d8
| device_register+0x20/0x30
| ffa_device_register+0x88/0xd8
| ffa_setup_partitions+0x108/0x1b8
| ffa_init+0x2ec/0x3a4
| do_one_initcall+0xcc/0x240
| do_initcall_level+0x8c/0xac
| do_initcalls+0x54/0x94
| do_basic_setup+0x1c/0x28
| kernel_init_freeable+0x100/0x16c
| kernel_init+0x20/0x1a0
| ret_from_fork+0x10/0x20
| kobject_add_internal failed for arm-ffa-8001 with -EEXIST, don't try to
| register things with the same name in the same directory.
| arm_ffa arm-ffa: unable to register device arm-ffa-8001 err=-17
| ARM FF-A: ffa_setup_partitions: failed to register partition ID 0x8001

By virtue of being random enough to avoid collisions when generated in a
distributed system, there is no way to compress UUID keys to the number
of bits required to identify each. We can eliminate '-' in the name but
it is not worth eliminating 4 bytes and add unnecessary logic for doing
that. Also v1.0 doesn't provide the UUID of the partitions which makes
it hard to use the same for the device name.

So to keep it simple, let us alloc an ID using ida_alloc() and append the
same to "arm-ffa" to make up a unique device name. Also stash the id value
in ffa_dev to help freeing the ID later when the device is destroyed.

Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Reported-by: Lucian Paul-Trifu <lucian.paul-trifu@arm.com>
Link: https://lore.kernel.org/r/20230419-ffa_fixes_6-4-v2-3-d9108e43a176@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Check if ffa_driver remove is present before executing

Currently ffa_drv->remove() is called unconditionally from
ffa_device_remove(). Since the driver registration doesn't check for it
and allows it to be registered without .remove callback, we need to check
for the presence of it before executing it from ffa_device_remove() to
above a NULL pointer dereference like the one below:

| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
| Mem abort info:
| ESR = 0x0000000086000004
| EC = 0x21: IABT (current EL), IL = 32 bits
| SET = 0, FnV = 0
| EA = 0, S1PTW = 0
| FSC = 0x04: level 0 translation fault
| user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881cc8000
| [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
| Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP
| CPU: 3 PID: 130 Comm: rmmod Not tainted 6.3.0-rc7 #6
| Hardware name: FVP Base RevC (DT)
| pstate: 63402809 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=-c)
| pc : 0x0
| lr : ffa_device_remove+0x20/0x2c
| Call trace:
| 0x0
| device_release_driver_internal+0x16c/0x260
| driver_detach+0x90/0xd0
| bus_remove_driver+0xdc/0x11c
| driver_unregister+0x30/0x54
| ffa_driver_unregister+0x14/0x20
| cleanup_module+0x18/0xeec
| __arm64_sys_delete_module+0x234/0x378
| invoke_syscall+0x40/0x108
| el0_svc_common+0xb4/0xf0
| do_el0_svc+0x30/0xa4
| el0_svc+0x2c/0x7c
| el0t_64_sync_handler+0x84/0xf0
| el0t_64_sync+0x190/0x194

Fixes: 244f5d597e1e ("firmware: arm_ffa: Add missing remove callback to ffa_bus_type")
Link: https://lore.kernel.org/r/20230419-ffa_fixes_6-4-v2-1-d9108e43a176@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

driver core: make struct bus_type.uevent() take a const *

The uevent() callback in struct bus_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-16-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: arm_ffa: Rename ffa_dev_ops as ffa_ops

Except the message APIs, all other APIs are ffa_device independent and can
be used without any associated ffa_device from a non ffa_driver.

In order to reflect the same, just rename ffa_dev_ops as ffa_ops to
avoid any confusion or to keep it simple.

Link: https://lore.kernel.org/r/20220907145240.1683088-8-sudeep.holla@arm.com
Suggested-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Add pointer to the ffa_dev_ops in struct ffa_dev

Currently ffa_dev_ops_get() is the way to fetch the ffa_dev_ops pointer.
It checks if the ffa_dev structure pointer is valid before returning the
ffa_dev_ops pointer.

Instead, the pointer can be made part of the ffa_dev structure and since
the core driver is incharge of creating ffa_device for each identified
partition, there is no need to check for the validity explicitly if the
pointer is embedded in the structure.

Add the pointer to the ffa_dev_ops in the ffa_dev structure itself and
initialise the same as part of creation of the device.

Link: https://lore.kernel.org/r/20220907145240.1683088-2-sudeep.holla@arm.com
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Fix __ffa_devices_unregister

When arm_ffa firmware driver module is unloaded or removed we call
__ffa_devices_unregister on all the devices on the ffa bus. It must
unregister all the devices instead it is currently just releasing the
devices without unregistering. That is pure wrong as when we try to
load the module back again, it will result in the kernel crash something
like below.

-->8
CPU: 2 PID: 232 Comm: modprobe Not tainted 5.15.0-rc2+ #169
Hardware name: FVP Base RevC (DT)
Call trace:
dump_backtrace+0x0/0x1cc
show_stack+0x18/0x64
dump_stack_lvl+0x64/0x7c
dump_stack+0x18/0x38
sysfs_create_dir_ns+0xe4/0x140
kobject_add_internal+0x170/0x358
kobject_add+0x94/0x100
device_add+0x178/0x5f0
device_register+0x20/0x30
ffa_device_register+0x80/0xcc [ffa_module]
ffa_setup_partitions+0x7c/0x108 [ffa_module]
init_module+0x290/0x2dc [ffa_module]
do_one_initcall+0xbc/0x230
do_init_module+0x58/0x304
load_module+0x15e0/0x1f68
__arm64_sys_finit_module+0xb8/0xf4
invoke_syscall+0x44/0x140
el0_svc_common+0xb4/0xf0
do_el0_svc+0x24/0x80
el0_svc+0x20/0x50
el0t_64_sync_handler+0x84/0xe4
el0t_64_sync+0x1a0/0x1a4
kobject_add_internal failed for arm-ffa-8001 with -EEXIST, don't try to
register things with the same name in the same directory.
----

Fix the issue by calling device_unregister in __ffa_devices_unregister
which will also take care of calling device_release(which is mapped to
ffa_release_device)

Link: https://lore.kernel.org/r/20210924092859.3057562-2-sudeep.holla@arm.com
Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Add missing remove callback to ffa_bus_type

Currently the arm_ffa firmware driver can be built as module and hence
all the users of FFA driver. If any driver on the ffa bus is removed or
unregistered, the remove callback on all the device bound to the driver
being removed should be callback. For that to happen, we must register
a remove callback on the ffa_bus which is currently missing. This results
in the probe getting called again without the previous remove callback
on a device which may result in kernel crash.

Fix the issue by registering the remove callback on the FFA bus.

Link: https://lore.kernel.org/r/20210924092859.3057562-1-sudeep.holla@arm.com
Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Reported-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Simplify probe function

When the driver core calls the probe callback it already checked that
the devices match, so there is no need to call the match callback again.

Link: https://lore.kernel.org/r/20210621201652.127611-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Ensure drivers provide a probe function

The bus probe callback calls the driver callback without further
checking. Better be safe than sorry and refuse registration of a driver
without a probe function to prevent a NULL pointer exception.

Link: https://lore.kernel.org/r/20210621201652.127611-1-u.kleine-koenig@pengutronix.de
Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Setup in-kernel users of FFA partitions

Parse the FFA nodes from the device-tree and register all the partitions
whose services will be used in the kernel.

In order to also enable in-kernel users of FFA interface, let us add
simple set of operations for such devices.

The in-kernel users are registered without the character device interface.

Link: https://lore.kernel.org/r/20210521151033.181846-5-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Add initial Arm FFA driver support

This just add a basic driver that sets up the transport(e.g. SMCCC),
checks the FFA version implemented, get the partition ID for self and
sets up the Tx/Rx buffers for communication.

Link: https://lore.kernel.org/r/20210521151033.181846-3-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_ffa: Add initial FFA bus support for device enumeration

The Arm FF for Armv8-A specification has concept of endpoints or
partitions. In the Normal world, a partition could be a VM when
the Virtualization extension is enabled or the kernel itself.

In order to handle multiple partitions, we can create a FFA device for
each such partition on a dedicated FFA bus. Similarly, different drivers
requiring FFA transport can be registered on the same bus. We can match
the device and drivers using UUID. This is mostly for the in-kernel
users with FFA drivers.

Link: https://lore.kernel.org/r/20210521151033.181846-2-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>