[Pdbg] [PATCH 5/7] libpdbg: Add bmc /dev/scom* backend

[Amitay Isaacs]

From: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Avoid using the CFAM in raw mode, thus avoiding racing with
other users of the CFAM PIB bridge. Also a bit faster.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
 libpdbg/kernel.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++
 p9-kernel.dts.m4 |  6 ++++--
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/libpdbg/kernel.c b/libpdbg/kernel.c
index 9ff0174..a759c3c 100644
--- a/libpdbg/kernel.c
+++ b/libpdbg/kernel.c
@@ -149,3 +149,59 @@ static struct fsi kernel_fsi = {
 	.write = kernel_fsi_putcfam,
 };
 DECLARE_HW_UNIT(kernel_fsi);
+
+static int kernel_pib_getscom(struct pib *pib, uint64_t addr, uint64_t *value)
+{
+	int rc;
+
+	rc = pread(pib->fd, value, 8, addr);
+	if (rc < 0) {
+		rc = errno;
+		PR_ERROR("Failed to read scom");
+		return rc;
+	}
+	return 0;
+}
+
+static int kernel_pib_putscom(struct pib *pib, uint64_t addr, uint64_t value)
+{
+	int rc;
+
+	rc = pwrite(pib->fd, &value, 8, addr);
+	if (rc < 0) {
+		rc = errno;
+		PR_ERROR("Failed to write scom");
+		return rc;
+	}
+	return 0;
+}
+
+static int kernel_pib_probe(struct pdbg_target *target)
+{
+	struct pib *pib = target_to_pib(target);
+	const char *scom_path;
+
+	scom_path = pdbg_target_property(target, "device-path", NULL);
+	assert(scom_path);
+
+	pib->fd = open(scom_path, O_RDWR | O_SYNC);
+	if (pib->fd < 0) {
+		PR_ERROR("Unable to open %s\n", scom_path);
+		return -1;
+	}
+
+	lseek(pib->fd, 0, SEEK_SET);
+	return 0;
+}
+
+struct pib kernel_pib = {
+	.target = {
+		.name =	"Kernel based FSI SCOM",
+		.compatible = "ibm,kernel-pib",
+		.class = "pib",
+		.probe = kernel_pib_probe,
+	},
+	.read = kernel_pib_getscom,
+	.write = kernel_pib_putscom,
+};
+DECLARE_HW_UNIT(kernel_pib);
diff --git a/p9-kernel.dts.m4 b/p9-kernel.dts.m4
index 195be59..aec0881 100644
--- a/p9-kernel.dts.m4
+++ b/p9-kernel.dts.m4
@@ -18,7 +18,8 @@
 			#size-cells = <0x1>;
 			reg = <0x0 0x1000 0x7>;
 			index = <0x0>;
-			compatible = "ibm,fsi-pib", "ibm,power9-fsi-pib";
+			compatible = "ibm,kernel-pib";
+			device-path = "/dev/scom1";
 			include(p9-pib.dts.m4)dnl
 		};
 
@@ -35,7 +36,8 @@
 				#size-cells = <0x1>;
 				 reg = <0x0 0x1000 0x7>;
 				 index = <0x1>;
-				 compatible = "ibm,fsi-pib", "ibm,power9-fsi-pib";
+				 compatible = "ibm,kernel-pib";
+				 device-path = "/dev/scom2";
 				 include(p9-pib.dts.m4)dnl
 			};
 		};
-- 
2.20.1