Merge tag 'arm-ffa-fixes-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/fixes

Arm FF-A fixes for v5.14

A small set of fixes:
- adding check for presence of probe while registering the driver to
  prevent NULL pointer access
- dropping the duplicate check as the driver core already takes care of it
- fixing possible ffa_linux_errmap buffer overflow and
- fixing kernel-doc warning for comment style

* tag 'arm-ffa-fixes-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_ffa: Fix a possible ffa_linux_errmap buffer overflow
  firmware: arm_ffa: Fix the comment style
  firmware: arm_ffa: Simplify probe function
  firmware: arm_ffa: Ensure drivers provide a probe function

Link: https://lore.kernel.org/r/20210714165806.2617325-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

drivers/firmware/arm_ffa/bus.c

@@ -46,9 +46,6 @@ 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);
 
-	if (!ffa_device_match(dev, dev->driver))
-		return -ENODEV;
-
 	return ffa_drv->probe(ffa_dev);
 }
 
@@ -99,6 +96,9 @@ int ffa_driver_register(struct ffa_driver *driver, struct module *owner,
 {
 	int ret;
 
+	if (!driver->probe)
+		return -EINVAL;
+
 	driver->driver.bus = &ffa_bus_type;
 	driver->driver.name = driver->name;
 	driver->driver.owner = owner;

drivers/firmware/arm_ffa/driver.c

@@ -120,7 +120,7 @@
 #define PACK_TARGET_INFO(s, r)		\
 	(FIELD_PREP(SENDER_ID_MASK, (s)) | FIELD_PREP(RECEIVER_ID_MASK, (r)))
 
-/**
+/*
  * FF-A specification mentions explicitly about '4K pages'. This should
  * not be confused with the kernel PAGE_SIZE, which is the translation
  * granule kernel is configured and may be one among 4K, 16K and 64K.
@@ -149,8 +149,10 @@ static const int ffa_linux_errmap[] = {
 
 static inline int ffa_to_linux_errno(int errno)
 {
-	if (errno < FFA_RET_SUCCESS && errno >= -ARRAY_SIZE(ffa_linux_errmap))
-		return ffa_linux_errmap[-errno];
+	int err_idx = -errno;
+
+	if (err_idx >= 0 && err_idx < ARRAY_SIZE(ffa_linux_errmap))
+		return ffa_linux_errmap[err_idx];
 	return -EINVAL;
 }