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authorMarco Pagani2024-03-05 20:29:26 +0100
committerXu Yilun2024-03-31 21:50:39 +0800
commit4d4d2d4346857bf778fafaa97d6f76bb1663e3c9 (patch)
tree1244dad0059e080171a59fa2e69f526744df63fa /Documentation/driver-api
parent4cece764965020c22cff7665b18a012006359095 (diff)
fpga: manager: add owner module and take its refcount
The current implementation of the fpga manager assumes that the low-level module registers a driver for the parent device and uses its owner pointer to take the module's refcount. This approach is problematic since it can lead to a null pointer dereference while attempting to get the manager if the parent device does not have a driver. To address this problem, add a module owner pointer to the fpga_manager struct and use it to take the module's refcount. Modify the functions for registering the manager to take an additional owner module parameter and rename them to avoid conflicts. Use the old function names for helper macros that automatically set the module that registers the manager as the owner. This ensures compatibility with existing low-level control modules and reduces the chances of registering a manager without setting the owner. Also, update the documentation to keep it consistent with the new interface for registering an fpga manager. Other changes: opportunistically move put_device() from __fpga_mgr_get() to fpga_mgr_get() and of_fpga_mgr_get() to improve code clarity since the manager device is taken in these functions. Fixes: 654ba4cc0f3e ("fpga manager: ensure lifetime with of_fpga_mgr_get") Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Suggested-by: Xu Yilun <yilun.xu@intel.com> Signed-off-by: Marco Pagani <marpagan@redhat.com> Acked-by: Xu Yilun <yilun.xu@intel.com> Link: https://lore.kernel.org/r/20240305192926.84886-1-marpagan@redhat.com Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/fpga/fpga-mgr.rst34
1 files changed, 20 insertions, 14 deletions
diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
index 49c0a9512653..8d2b79f696c1 100644
--- a/Documentation/driver-api/fpga/fpga-mgr.rst
+++ b/Documentation/driver-api/fpga/fpga-mgr.rst
@@ -24,7 +24,8 @@ How to support a new FPGA device
--------------------------------
To add another FPGA manager, write a driver that implements a set of ops. The
-probe function calls fpga_mgr_register() or fpga_mgr_register_full(), such as::
+probe function calls ``fpga_mgr_register()`` or ``fpga_mgr_register_full()``,
+such as::
static const struct fpga_manager_ops socfpga_fpga_ops = {
.write_init = socfpga_fpga_ops_configure_init,
@@ -69,10 +70,11 @@ probe function calls fpga_mgr_register() or fpga_mgr_register_full(), such as::
}
Alternatively, the probe function could call one of the resource managed
-register functions, devm_fpga_mgr_register() or devm_fpga_mgr_register_full().
-When these functions are used, the parameter syntax is the same, but the call
-to fpga_mgr_unregister() should be removed. In the above example, the
-socfpga_fpga_remove() function would not be required.
+register functions, ``devm_fpga_mgr_register()`` or
+``devm_fpga_mgr_register_full()``. When these functions are used, the
+parameter syntax is the same, but the call to ``fpga_mgr_unregister()`` should be
+removed. In the above example, the ``socfpga_fpga_remove()`` function would not be
+required.
The ops will implement whatever device specific register writes are needed to
do the programming sequence for this particular FPGA. These ops return 0 for
@@ -125,15 +127,19 @@ API for implementing a new FPGA Manager driver
* struct fpga_manager - the FPGA manager struct
* struct fpga_manager_ops - Low level FPGA manager driver ops
* struct fpga_manager_info - Parameter structure for fpga_mgr_register_full()
-* fpga_mgr_register_full() - Create and register an FPGA manager using the
+* __fpga_mgr_register_full() - Create and register an FPGA manager using the
fpga_mgr_info structure to provide the full flexibility of options
-* fpga_mgr_register() - Create and register an FPGA manager using standard
+* __fpga_mgr_register() - Create and register an FPGA manager using standard
arguments
-* devm_fpga_mgr_register_full() - Resource managed version of
- fpga_mgr_register_full()
-* devm_fpga_mgr_register() - Resource managed version of fpga_mgr_register()
+* __devm_fpga_mgr_register_full() - Resource managed version of
+ __fpga_mgr_register_full()
+* __devm_fpga_mgr_register() - Resource managed version of __fpga_mgr_register()
* fpga_mgr_unregister() - Unregister an FPGA manager
+Helper macros ``fpga_mgr_register_full()``, ``fpga_mgr_register()``,
+``devm_fpga_mgr_register_full()``, and ``devm_fpga_mgr_register()`` are available
+to ease the registration.
+
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_mgr_states
@@ -147,16 +153,16 @@ API for implementing a new FPGA Manager driver
:functions: fpga_manager_info
.. kernel-doc:: drivers/fpga/fpga-mgr.c
- :functions: fpga_mgr_register_full
+ :functions: __fpga_mgr_register_full
.. kernel-doc:: drivers/fpga/fpga-mgr.c
- :functions: fpga_mgr_register
+ :functions: __fpga_mgr_register
.. kernel-doc:: drivers/fpga/fpga-mgr.c
- :functions: devm_fpga_mgr_register_full
+ :functions: __devm_fpga_mgr_register_full
.. kernel-doc:: drivers/fpga/fpga-mgr.c
- :functions: devm_fpga_mgr_register
+ :functions: __devm_fpga_mgr_register
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_unregister