powerpc/rtas_pci: rename and properly expose config access APIs

The rtas_read_config() and rtas_write_config() functions in
kernel/rtas_pci.c have external linkage and two users in arch/powerpc:
the rtas_pci code itself and the pseries platform's "enhanced error
handling" (EEH) support code.

The prototypes for these functions in asm/ppc-pci.h have until now
been guarded by CONFIG_EEH since the only external caller is the
pseries EEH code. However, this presumably has always generated
warnings when built with !CONFIG_EEH and -Wmissing-prototypes:

  arch/powerpc/kernel/rtas_pci.c:46:5: error: no previous prototype for
  function 'rtas_read_config' [-Werror,-Wmissing-prototypes]
     46 | int rtas_read_config(struct pci_dn *pdn, int where,
                               int size, u32 *val)

  arch/powerpc/kernel/rtas_pci.c:98:5: error: no previous prototype for
  function 'rtas_write_config' [-Werror,-Wmissing-prototypes]
     98 | int rtas_write_config(struct pci_dn *pdn, int where,
                                int size, u32 val)

The introduction of commit c6345dfa6e3e ("Makefile.extrawarn: turn on
missing-prototypes globally") forces the issue.

The efika and chrp platform code have (static) functions with the same
names but different signatures. We may as well eliminate the potential
for conflicts and confusion by renaming the globally visible versions
as their prototypes get moved out of the CONFIG_EEH-guarded region;
their current names are too generic anyway. Since they operate on
objects of the type 'struct pci_dn *', give them the slightly more
verbose prefix "rtas_pci_dn_" and fix up all the call sites.

Fixes: c6345dfa6e3e ("Makefile.extrawarn: turn on missing-prototypes globally")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/linuxppc-dev/CA+G9fYt0LLXtjSz+Hkf3Fhm-kf0ZQanrhUS+zVZGa3O+Wt2+vg@mail.gmail.com/
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231127-rtas-pci-rw-config-v1-1-385d29ace3df@linux.ibm.com

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/ppc-pci.h b/arch/powerpc/include/asm/ppc-pci.h
index d9fcff575027..ce2b1b5eebdd 100644
--- a/arch/powerpc/include/asm/ppc-pci.h
+++ b/arch/powerpc/include/asm/ppc-pci.h
@@ -35,6 +35,9 @@ extern void init_pci_config_tokens (void);
 extern unsigned long get_phb_buid (struct device_node *);
 extern int rtas_setup_phb(struct pci_controller *phb);
 
+int rtas_pci_dn_read_config(struct pci_dn *pdn, int where, int size, u32 *val);
+int rtas_pci_dn_write_config(struct pci_dn *pdn, int where, int size, u32 val);
+
 #ifdef CONFIG_EEH
 
 void eeh_addr_cache_insert_dev(struct pci_dev *dev);
@@ -44,8 +47,6 @@ void eeh_slot_error_detail(struct eeh_pe *pe, int severity);
 int eeh_pci_enable(struct eeh_pe *pe, int function);
 int eeh_pe_reset_full(struct eeh_pe *pe, bool include_passed);
 void eeh_save_bars(struct eeh_dev *edev);
-int rtas_write_config(struct pci_dn *, int where, int size, u32 val);
-int rtas_read_config(struct pci_dn *, int where, int size, u32 *val);
 void eeh_pe_state_mark(struct eeh_pe *pe, int state);
 void eeh_pe_mark_isolated(struct eeh_pe *pe);
 void eeh_pe_state_clear(struct eeh_pe *pe, int state, bool include_passed);