linux-kernel - [PATCH v2 06/12] MIPS: pm-cps: Use MIPS standard lightweight ordering barrier

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Date:   Wed, 7 Sep 2016 10:45:14 +0100
From:   Matt Redfearn <matt.redfearn@...tec.com>
To:     Ralf Baechle <ralf@...ux-mips.org>
CC:     <linux-mips@...ux-mips.org>,
        Matt Redfearn <matt.redfearn@...tec.com>,
        Adam Buchbinder <adam.buchbinder@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        <linux-kernel@...r.kernel.org>,
        Markos Chandras <markos.chandras@...tec.com>,
        Paul Burton <paul.burton@...tec.com>
Subject: [PATCH v2 06/12] MIPS: pm-cps: Use MIPS standard lightweight ordering barrier

Since R2 of the MIPS architecture, SYNC(0x10) has been an optional but
architecturally defined ordering barrier. If a CPU does not implement it,
the arch specifies that it must fall back to SYNC(0).

In places where we require that the instruction stream not be reordered,
but do not require that loads / stores are gloablly completed, use the
defined standard sync stype.

Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>
Reviewed-by: Paul Burton <paul.burton@...tec.com>
---

Changes in v2: None

 arch/mips/kernel/pm-cps.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/mips/kernel/pm-cps.c b/arch/mips/kernel/pm-cps.c
index 7e8d4aa22233..d7037fe00d1c 100644
--- a/arch/mips/kernel/pm-cps.c
+++ b/arch/mips/kernel/pm-cps.c
@@ -76,7 +76,6 @@ static struct uasm_reloc relocs[32] __initdata;
 /* CPU dependant sync types */
 static unsigned stype_intervention;
 static unsigned stype_memory;
-static unsigned stype_ordering;
 
 enum mips_reg {
 	zero, at, v0, v1, a0, a1, a2, a3,
@@ -406,7 +405,7 @@ static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 
 	if (coupled_coherence) {
 		/* Increment ready_count */
-		uasm_i_sync(&p, stype_ordering);
+		uasm_i_sync(&p, STYPE_SYNC_MB);
 		uasm_build_label(&l, p, lbl_incready);
 		uasm_i_ll(&p, t1, 0, r_nc_count);
 		uasm_i_addiu(&p, t2, t1, 1);
@@ -415,7 +414,7 @@ static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 		uasm_i_addiu(&p, t1, t1, 1);
 
 		/* Barrier ensuring all CPUs see the updated r_nc_count value */
-		uasm_i_sync(&p, stype_ordering);
+		uasm_i_sync(&p, STYPE_SYNC_MB);
 
 		/*
 		 * If this is the last VPE to become ready for non-coherence
@@ -568,7 +567,7 @@ static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 	if (coupled_coherence && (state == CPS_PM_NC_WAIT)) {
 		/* Decrement ready_count */
 		uasm_build_label(&l, p, lbl_decready);
-		uasm_i_sync(&p, stype_ordering);
+		uasm_i_sync(&p, STYPE_SYNC_MB);
 		uasm_i_ll(&p, t1, 0, r_nc_count);
 		uasm_i_addiu(&p, t2, t1, -1);
 		uasm_i_sc(&p, t2, 0, r_nc_count);
@@ -576,7 +575,7 @@ static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 		uasm_i_andi(&p, v0, t1, (1 << fls(smp_num_siblings)) - 1);
 
 		/* Barrier ensuring all CPUs see the updated r_nc_count value */
-		uasm_i_sync(&p, stype_ordering);
+		uasm_i_sync(&p, STYPE_SYNC_MB);
 	}
 
 	if (coupled_coherence && (state == CPS_PM_CLOCK_GATED)) {
@@ -598,7 +597,7 @@ static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 		uasm_build_label(&l, p, lbl_secondary_cont);
 
 		/* Barrier ensuring all CPUs see the updated r_nc_count value */
-		uasm_i_sync(&p, stype_ordering);
+		uasm_i_sync(&p, STYPE_SYNC_MB);
 	}
 
 	/* The core is coherent, time to return to C code */
@@ -677,7 +676,6 @@ static int __init cps_pm_init(void)
 	case CPU_I6400:
 		stype_intervention = 0x2;
 		stype_memory = 0x3;
-		stype_ordering = 0x10;
 		break;
 
 	default:
-- 
2.7.4