[Skiboot] [PATCH v2] core/init: remove master_cpu parameter

[Oliver O'Halloran]

master_cpu is used to determine the ChipTOD master if no ChipTOD
information is available in the HDAT. However, it is set to zero at every
skiboot entry point (fdt_entry, the 0x180 FSP entry and
opal_boot_trampoline) and is otherwise unused. This patch removes this
passing around and uses the boot CPU PIR to find the ChipTOD master rather
than zero.

Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
 asm/head.S               |  5 -----
 core/init.c              |  8 ++++----
 hdata/spira.c            | 15 ++++++---------
 hdata/test/hdata_to_dt.c |  2 +-
 include/skiboot.h        |  2 +-
 5 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/asm/head.S b/asm/head.S
index 60bdbe8bba86..a4105ca4812b 100644
--- a/asm/head.S
+++ b/asm/head.S
@@ -57,7 +57,6 @@ __head:
 .global fdt_entry
 fdt_entry:
 	mr	%r27,%r3
-	li	%r25,0
 	b	boot_entry
 
 	/* This is a pointer to a descriptor used by debugging tools
@@ -109,7 +108,6 @@ hir_trigger:
 	/* Entry point set by the FSP */
 	.= 0x180
 	li	%r27,0
-	li	%r25,0
 	b	boot_entry
 
 #define EXCEPTION(nr)		\
@@ -249,7 +247,6 @@ boot_offset:
  *   r28 :  PVR
  *   r27 :  DTB pointer (or NULL)
  *   r26 :  PIR thread mask
- *   r25 :  Selected master CPU (OPAL boot)
  */
 .global boot_entry
 boot_entry:
@@ -390,7 +387,6 @@ boot_entry:
 #endif
 	/* Jump to C */
 	mr	%r3,%r27
-	mr	%r4,%r25
 	bl	main_cpu_entry
 	b	.
 
@@ -819,7 +815,6 @@ opal_naca:
 	 * got to the same entry we use for pHyp and FDT HB.
 	 */
 opal_boot_trampoline:
-	li	%r25,0
 	li	%r27,-1
 	ba	boot_entry - __head
 
diff --git a/core/init.c b/core/init.c
index a2daddb86d0b..db03d9777f5b 100644
--- a/core/init.c
+++ b/core/init.c
@@ -645,9 +645,9 @@ static void per_thread_sanity_checks(void)
 }
 
 /* Called from head.S, thus no prototype. */
-void main_cpu_entry(const void *fdt, u32 master_cpu);
+void main_cpu_entry(const void *fdt);
 
-void __noreturn __nomcount main_cpu_entry(const void *fdt, u32 master_cpu)
+void __noreturn __nomcount main_cpu_entry(const void *fdt)
 {
 	/*
 	 * WARNING: At this point. the timebases have
@@ -711,10 +711,10 @@ void __noreturn __nomcount main_cpu_entry(const void *fdt, u32 master_cpu)
 	dt_root = dt_new_root("");
 
 	if (fdt == (void *)-1ul) {
-		if (parse_hdat(true, master_cpu) < 0)
+		if (parse_hdat(true) < 0)
 			abort();
 	} else if (fdt == NULL) {
-		if (parse_hdat(false, master_cpu) < 0)
+		if (parse_hdat(false) < 0)
 			abort();
 	} else {
 		dt_expand(fdt);
diff --git a/hdata/spira.c b/hdata/spira.c
index 51d918f87481..6f384fdc7450 100644
--- a/hdata/spira.c
+++ b/hdata/spira.c
@@ -624,10 +624,10 @@ static bool add_chiptod_old(void)
 	return found;
 }
 
-static bool add_chiptod_new(uint32_t master_cpu)
+static bool add_chiptod_new(void)
 {
 	const void *hdif;
-	unsigned int i, master_chip;
+	unsigned int i;
 	bool found = false;
 
 	/*
@@ -636,8 +636,6 @@ static bool add_chiptod_new(uint32_t master_cpu)
 	if (!get_hdif(&spira.ntuples.proc_chip, SPPCRD_HDIF_SIG))
 		return found;
 
-	master_chip = pir_to_chip_id(master_cpu);
-
 	for_each_ntuple_idx(&spira.ntuples.proc_chip, hdif, i,
 			    SPPCRD_HDIF_SIG) {
 		const struct sppcrd_chip_info *cinfo;
@@ -668,12 +666,11 @@ static bool add_chiptod_new(uint32_t master_cpu)
 		/* The FSP may strip the chiptod info from HDAT; if we find
 		 * a zero-ed out entry, assume that the chiptod is
 		 * present, but we don't have any primary/secondary info. In
-		 * this case, pick the primary based on the CPU that was
-		 * assigned master.
+		 * this case, pick chip zero as the master.
 		 */
 		if (!size) {
 			flags = CHIPTOD_ID_FLAGS_STATUS_OK;
-			if (be32_to_cpu(cinfo->xscom_id) == master_chip)
+			if (be32_to_cpu(cinfo->xscom_id) == 0x0)
 				flags |= CHIPTOD_ID_FLAGS_PRIMARY;
 		}
 
@@ -1092,7 +1089,7 @@ static void fixup_spira(void)
 	spira.ntuples.hs_data = spiras->ntuples.hs_data;
 }
 
-int parse_hdat(bool is_opal, uint32_t master_cpu)
+int parse_hdat(bool is_opal)
 {
 	cpu_type = PVR_TYPE(mfspr(SPR_PVR));
 
@@ -1131,7 +1128,7 @@ int parse_hdat(bool is_opal, uint32_t master_cpu)
 	fsp_parse();
 
 	/* Add ChipTOD's */
-	if (!add_chiptod_old() && !add_chiptod_new(master_cpu))
+	if (!add_chiptod_old() && !add_chiptod_new())
 		prerror("CHIPTOD: No ChipTOD found !\n");
 
 	/* Add NX */
diff --git a/hdata/test/hdata_to_dt.c b/hdata/test/hdata_to_dt.c
index 1a644301986d..06f900544fcb 100644
--- a/hdata/test/hdata_to_dt.c
+++ b/hdata/test/hdata_to_dt.c
@@ -234,7 +234,7 @@ int main(int argc, char *argv[])
 
 	dt_root = dt_new_root("");
 
-	if(parse_hdat(false, 0) < 0) {
+	if(parse_hdat(false) < 0) {
 		fprintf(stderr, "FATAL ERROR parsing HDAT\n");
 		exit(EXIT_FAILURE);
 	}
diff --git a/include/skiboot.h b/include/skiboot.h
index 4ccf46d9e565..52a235b57beb 100644
--- a/include/skiboot.h
+++ b/include/skiboot.h
@@ -175,7 +175,7 @@ extern void start_kernel32(uint64_t entry, void* fdt,
 extern void start_kernel_secondary(uint64_t entry) __noreturn;
 
 /* Get description of machine from HDAT and create device-tree */
-extern int parse_hdat(bool is_opal, uint32_t master_cpu);
+extern int parse_hdat(bool is_opal);
 
 /* Root of device tree. */
 extern struct dt_node *dt_root;
-- 
2.5.5