[Xen-devel] [PATCH v2 6/6] ARM: mach-virt: add SMP support using PSCI
Stefano Stabellini
stefano.stabellini at eu.citrix.com
Tue Dec 18 07:19:40 EST 2012
On Mon, 17 Dec 2012, Will Deacon wrote:
> This patch adds support for SMP to mach-virt using the PSCI
> infrastructure.
>
> Signed-off-by: Will Deacon <will.deacon at arm.com>
>
> arch/arm/mach-virt/Kconfig | 1 +
> arch/arm/mach-virt/Makefile | 1 +
> arch/arm/mach-virt/platsmp.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
> arch/arm/mach-virt/virt.c | 6 ++++
> 4 files changed, 84 insertions(+)
> create mode 100644 arch/arm/mach-virt/platsmp.c
>
> diff --git a/arch/arm/mach-virt/Kconfig b/arch/arm/mach-virt/Kconfig
> index a568a2a..8958f0d 100644
> --- a/arch/arm/mach-virt/Kconfig
> +++ b/arch/arm/mach-virt/Kconfig
> @@ -3,6 +3,7 @@ config ARCH_VIRT
> select ARCH_WANT_OPTIONAL_GPIOLIB
> select ARM_GIC
> select ARM_ARCH_TIMER
> + select ARM_PSCI
> select HAVE_SMP
> select CPU_V7
> select SPARSE_IRQ
Considering that PSCI is actually needed only to boot secondary cpus,
maybe we want to select it if CONFIG_SMP is enabled?
> diff --git a/arch/arm/mach-virt/Makefile b/arch/arm/mach-virt/Makefile
> index 7ddbfa6..042afc1 100644
> --- a/arch/arm/mach-virt/Makefile
> +++ b/arch/arm/mach-virt/Makefile
> @@ -3,3 +3,4 @@
> #
>
> obj-y := virt.o
> +obj-$(CONFIG_SMP) += platsmp.o
> diff --git a/arch/arm/mach-virt/platsmp.c b/arch/arm/mach-virt/platsmp.c
> new file mode 100644
> index 0000000..930362b
> --- /dev/null
> +++ b/arch/arm/mach-virt/platsmp.c
> @@ -0,0 +1,76 @@
> +/*
> + * Dummy Virtual Machine - does what it says on the tin.
> + *
> + * Copyright (C) 2012 ARM Ltd
> + * Author: Will Deacon <will.deacon at arm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/smp.h>
> +#include <linux/of.h>
> +
> +#include <asm/psci.h>
> +#include <asm/smp_plat.h>
> +#include <asm/hardware/gic.h>
> +
> +extern void secondary_startup(void);
> +
> +/*
> + * Enumerate the possible CPU set from the device tree.
> + */
> +static void __init virt_smp_init_cpus(void)
> +{
> + struct device_node *dn = NULL;
> + int cpu = 0;
> +
> + while ((dn = of_find_node_by_type(dn, "cpu"))) {
> + if (cpu < NR_CPUS)
> + set_cpu_possible(cpu, true);
> + cpu++;
> + }
> +
> + /* sanity check */
> + if (cpu > NR_CPUS)
> + pr_warning("no. of cores (%d) greater than configured maximum "
> + "of %d - clipping\n",
> + cpu, NR_CPUS);
> +
> + set_smp_cross_call(gic_raise_softirq);
> +}
> +
> +static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +}
> +
> +static int __cpuinit virt_boot_secondary(unsigned int cpu,
> + struct task_struct *idle)
> +{
> + if (psci_ops.cpu_on)
> + return psci_ops.cpu_on(cpu_logical_map(cpu),
> + __pa(secondary_startup));
> + return -ENODEV;
> +}
Isn't there a better way to check whether PSCI is actually "enabled", as
in present in the device tree and initialized correctly?
Maybe we need a pcsi_enabled() static inline of some sort?
> +static void __cpuinit virt_secondary_init(unsigned int cpu)
> +{
> + gic_secondary_init(0);
> +}
> +
> +struct smp_operations __initdata virt_smp_ops = {
> + .smp_init_cpus = virt_smp_init_cpus,
> + .smp_prepare_cpus = virt_smp_prepare_cpus,
> + .smp_secondary_init = virt_secondary_init,
> + .smp_boot_secondary = virt_boot_secondary,
> +};
> diff --git a/arch/arm/mach-virt/virt.c b/arch/arm/mach-virt/virt.c
> index 174b9da..d764835 100644
> --- a/arch/arm/mach-virt/virt.c
> +++ b/arch/arm/mach-virt/virt.c
> @@ -20,6 +20,7 @@
>
> #include <linux/of_irq.h>
> #include <linux/of_platform.h>
> +#include <linux/smp.h>
>
> #include <asm/arch_timer.h>
> #include <asm/hardware/gic.h>
> @@ -56,10 +57,15 @@ static struct sys_timer virt_timer = {
> .init = virt_timer_init,
> };
>
> +#ifdef CONFIG_SMP
> +extern struct smp_operations virt_smp_ops;
> +#endif
> +
> DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
> .init_irq = gic_init_irq,
> .handle_irq = gic_handle_irq,
> .timer = &virt_timer,
> .init_machine = virt_init,
> + .smp = smp_ops(virt_smp_ops),
> .dt_compat = virt_dt_match,
> MACHINE_END
> --
> 1.8.0
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