On 11/05/2012 03:02 PM, Will Deacon wrote: > Hi Gregory, Hi Will,
> > On Mon, Oct 29, 2012 at 09:11:44PM +0000, Gregory CLEMENT wrote: >> 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 <[email protected]> >> + * Gregory Clement <[email protected]> >> + * Thomas Petazzoni <[email protected]> >> + * >> + * 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? I forward this question to the Marvell experts. > > Will > > _______________________________________________ > linux-arm-kernel mailing list > [email protected] > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
