[PATCH V2 1/5] arm: mvebu: Added support for coherency fabric in mach-mvebu
From: Will Deacon <hidden>
Date: 2012-11-05 14:02:58
Also in:
linux-devicetree
Hi Gregory, On Mon, Oct 29, 2012 at 09:11:44PM +0000, Gregory CLEMENT wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c new file mode 100644 index 0000000..69e130d --- /dev/null +++ b/arch/arm/mach-mvebu/coherency.c@@ -0,0 +1,89 @@ +/* + * Coherency fabric (Aurora) support for Armada 370 and XP platforms. + * + * Copyright (C) 2012 Marvell + * + * Yehuda Yitschak <yehuday@marvell.com> + * Gregory Clement <gregory.clement@free-electrons.com> + * Thomas Petazzoni <thomas.petazzoni@free-electrons.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + * + * The Armada 370 and Armada XP SOCs have a coherency fabric which is + * responsible for ensuring hardware coherency between all CPUs and between + * CPUs and I/O masters. This file initializes the coherency fabric and + * supplies basic routines for configuring and controlling hardware coherency + */
[...]
+int set_cpu_coherent(unsigned int hw_cpu_id, int smp_group_id)
+{
+ int reg;
+
+ if (!coherency_base) {
+ pr_warn("Can't make CPU %d cache coherent.\n", hw_cpu_id);
+ pr_warn("Coherency fabric is not initialized\n");
+ return 1;
+ }
+
+ /* Enable the CPU in coherency fabric */
+ reg = readl(coherency_base + COHERENCY_FABRIC_CTL_OFFSET);
+ reg |= 1 << (24 + hw_cpu_id);
+ writel(reg, coherency_base + COHERENCY_FABRIC_CTL_OFFSET);
+
+ /* Add CPU to SMP group */
+ reg = readl(coherency_base + COHERENCY_FABRIC_CFG_OFFSET);
+ reg |= 1 << (16 + hw_cpu_id + (smp_group_id == 0 ? 8 : 0));
+ writel(reg, coherency_base + COHERENCY_FABRIC_CFG_OFFSET);
+
+ return 0;
+}These writels may expand to code containing calls to outer_sync(), which will attempt to take a spinlock for the aurora l2. Given that the CPU isn't coherent, how does this play out with the exclusive store instruction in the lock? Will