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, 9 insertions, 9 deletions

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index def184da51cf..b1ae0c0d1187 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -252,7 +252,7 @@ static int pseries_eeh_cap_start(struct pci_dn *pdn)
 	if (!pdn)
 		return 0;
 
-	rtas_read_config(pdn, PCI_STATUS, 2, &status);
+	rtas_pci_dn_read_config(pdn, PCI_STATUS, 2, &status);
 	if (!(status & PCI_STATUS_CAP_LIST))
 		return 0;
 
@@ -270,11 +270,11 @@ static int pseries_eeh_find_cap(struct pci_dn *pdn, int cap)
 		return 0;
 
         while (cnt--) {
-		rtas_read_config(pdn, pos, 1, &pos);
+		rtas_pci_dn_read_config(pdn, pos, 1, &pos);
 		if (pos < 0x40)
 			break;
 		pos &= ~3;
-		rtas_read_config(pdn, pos + PCI_CAP_LIST_ID, 1, &id);
+		rtas_pci_dn_read_config(pdn, pos + PCI_CAP_LIST_ID, 1, &id);
 		if (id == 0xff)
 			break;
 		if (id == cap)
@@ -294,7 +294,7 @@ static int pseries_eeh_find_ecap(struct pci_dn *pdn, int cap)
 
 	if (!edev || !edev->pcie_cap)
 		return 0;
-	if (rtas_read_config(pdn, pos, 4, &header) != PCIBIOS_SUCCESSFUL)
+	if (rtas_pci_dn_read_config(pdn, pos, 4, &header) != PCIBIOS_SUCCESSFUL)
 		return 0;
 	else if (!header)
 		return 0;
@@ -307,7 +307,7 @@ static int pseries_eeh_find_ecap(struct pci_dn *pdn, int cap)
 		if (pos < 256)
 			break;
 
-		if (rtas_read_config(pdn, pos, 4, &header) != PCIBIOS_SUCCESSFUL)
+		if (rtas_pci_dn_read_config(pdn, pos, 4, &header) != PCIBIOS_SUCCESSFUL)
 			break;
 	}
 
@@ -412,8 +412,8 @@ static void pseries_eeh_init_edev(struct pci_dn *pdn)
 	if ((pdn->class_code >> 8) == PCI_CLASS_BRIDGE_PCI) {
 		edev->mode |= EEH_DEV_BRIDGE;
 		if (edev->pcie_cap) {
-			rtas_read_config(pdn, edev->pcie_cap + PCI_EXP_FLAGS,
-					 2, &pcie_flags);
+			rtas_pci_dn_read_config(pdn, edev->pcie_cap + PCI_EXP_FLAGS,
+						2, &pcie_flags);
 			pcie_flags = (pcie_flags & PCI_EXP_FLAGS_TYPE) >> 4;
 			if (pcie_flags == PCI_EXP_TYPE_ROOT_PORT)
 				edev->mode |= EEH_DEV_ROOT_PORT;
@@ -676,7 +676,7 @@ static int pseries_eeh_read_config(struct eeh_dev *edev, int where, int size, u3
 {
 	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
 
-	return rtas_read_config(pdn, where, size, val);
+	return rtas_pci_dn_read_config(pdn, where, size, val);
 }
 
 /**
@@ -692,7 +692,7 @@ static int pseries_eeh_write_config(struct eeh_dev *edev, int where, int size, u
 {
 	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
 
-	return rtas_write_config(pdn, where, size, val);
+	return rtas_pci_dn_write_config(pdn, where, size, val);
 }
 
 #ifdef CONFIG_PCI_IOV