diff options
Diffstat (limited to 'arch/arm/plat-versatile')
| -rw-r--r-- | arch/arm/plat-versatile/Makefile | 5 | ||||
| -rw-r--r-- | arch/arm/plat-versatile/headsmp.S | 38 | ||||
| -rw-r--r-- | arch/arm/plat-versatile/hotplug.c | 102 | ||||
| -rw-r--r-- | arch/arm/plat-versatile/include/plat/platsmp.h | 13 | ||||
| -rw-r--r-- | arch/arm/plat-versatile/platsmp.c | 109 |
5 files changed, 267 insertions, 0 deletions
diff --git a/arch/arm/plat-versatile/Makefile b/arch/arm/plat-versatile/Makefile new file mode 100644 index 000000000..5de44a57c --- /dev/null +++ b/arch/arm/plat-versatile/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0-only +ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include + +obj-$(CONFIG_SMP) += headsmp.o platsmp.o +obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o diff --git a/arch/arm/plat-versatile/headsmp.S b/arch/arm/plat-versatile/headsmp.S new file mode 100644 index 000000000..09d9fc30c --- /dev/null +++ b/arch/arm/plat-versatile/headsmp.S @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/plat-versatile/headsmp.S + * + * Copyright (c) 2003 ARM Limited + * All Rights Reserved + */ +#include <linux/linkage.h> +#include <linux/init.h> +#include <asm/assembler.h> + +/* + * Realview/Versatile Express specific entry point for secondary CPUs. + * This provides a "holding pen" into which all secondary cores are held + * until we're ready for them to initialise. + */ +ENTRY(versatile_secondary_startup) + ARM_BE8(setend be) + mrc p15, 0, r0, c0, c0, 5 + bic r0, #0xff000000 + adr r4, 1f + ldmia r4, {r5, r6} + sub r4, r4, r5 + add r6, r6, r4 +pen: ldr r7, [r6] + cmp r7, r0 + bne pen + + /* + * we've been released from the holding pen: secondary_stack + * should now contain the SVC stack for this core + */ + b secondary_startup + + .align +1: .long . + .long versatile_cpu_release +ENDPROC(versatile_secondary_startup) diff --git a/arch/arm/plat-versatile/hotplug.c b/arch/arm/plat-versatile/hotplug.c new file mode 100644 index 000000000..2e9dca38b --- /dev/null +++ b/arch/arm/plat-versatile/hotplug.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2002 ARM Ltd. + * All Rights Reserved + * + * This hotplug implementation is _specific_ to the situation found on + * ARM development platforms where there is _no_ possibility of actually + * taking a CPU offline, resetting it, or otherwise. Real platforms must + * NOT copy this code. + */ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/smp.h> + +#include <asm/smp_plat.h> +#include <asm/cp15.h> + +#include <plat/platsmp.h> + +static inline void versatile_immitation_enter_lowpower(unsigned int actrl_mask) +{ + unsigned int v; + + asm volatile( + "mcr p15, 0, %1, c7, c5, 0\n" + " mcr p15, 0, %1, c7, c10, 4\n" + /* + * Turn off coherency + */ + " mrc p15, 0, %0, c1, c0, 1\n" + " bic %0, %0, %3\n" + " mcr p15, 0, %0, c1, c0, 1\n" + " mrc p15, 0, %0, c1, c0, 0\n" + " bic %0, %0, %2\n" + " mcr p15, 0, %0, c1, c0, 0\n" + : "=&r" (v) + : "r" (0), "Ir" (CR_C), "Ir" (actrl_mask) + : "cc"); +} + +static inline void versatile_immitation_leave_lowpower(unsigned int actrl_mask) +{ + unsigned int v; + + asm volatile( + "mrc p15, 0, %0, c1, c0, 0\n" + " orr %0, %0, %1\n" + " mcr p15, 0, %0, c1, c0, 0\n" + " mrc p15, 0, %0, c1, c0, 1\n" + " orr %0, %0, %2\n" + " mcr p15, 0, %0, c1, c0, 1\n" + : "=&r" (v) + : "Ir" (CR_C), "Ir" (actrl_mask) + : "cc"); +} + +static inline void versatile_immitation_do_lowpower(unsigned int cpu, int *spurious) +{ + /* + * there is no power-control hardware on this platform, so all + * we can do is put the core into WFI; this is safe as the calling + * code will have already disabled interrupts. + * + * This code should not be used outside Versatile platforms. + */ + for (;;) { + wfi(); + + if (versatile_cpu_release == cpu_logical_map(cpu)) { + /* + * OK, proper wakeup, we're done + */ + break; + } + + /* + * Getting here, means that we have come out of WFI without + * having been woken up - this shouldn't happen + * + * Just note it happening - when we're woken, we can report + * its occurrence. + */ + (*spurious)++; + } +} + +/* + * platform-specific code to shutdown a CPU. + * This code supports immitation-style CPU hotplug for Versatile/Realview/ + * Versatile Express platforms that are unable to do real CPU hotplug. + */ +void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask) +{ + int spurious = 0; + + versatile_immitation_enter_lowpower(actrl_mask); + versatile_immitation_do_lowpower(cpu, &spurious); + versatile_immitation_leave_lowpower(actrl_mask); + + if (spurious) + pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); +} diff --git a/arch/arm/plat-versatile/include/plat/platsmp.h b/arch/arm/plat-versatile/include/plat/platsmp.h new file mode 100644 index 000000000..500605f48 --- /dev/null +++ b/arch/arm/plat-versatile/include/plat/platsmp.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/plat-versatile/include/plat/platsmp.h + * + * Copyright (C) 2011 ARM Ltd. + * All Rights Reserved + */ +extern volatile int versatile_cpu_release; + +extern void versatile_secondary_startup(void); +extern void versatile_secondary_init(unsigned int cpu); +extern int versatile_boot_secondary(unsigned int cpu, struct task_struct *idle); +void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask); diff --git a/arch/arm/plat-versatile/platsmp.c b/arch/arm/plat-versatile/platsmp.c new file mode 100644 index 000000000..3567296ce --- /dev/null +++ b/arch/arm/plat-versatile/platsmp.c @@ -0,0 +1,109 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/plat-versatile/platsmp.c + * + * Copyright (C) 2002 ARM Ltd. + * All Rights Reserved + * + * This code is specific to the hardware found on ARM Realview and + * Versatile Express platforms where the CPUs are unable to be individually + * woken, and where there is no way to hot-unplug CPUs. Real platforms + * should not copy this code. + */ +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/jiffies.h> +#include <linux/smp.h> + +#include <asm/cacheflush.h> +#include <asm/smp_plat.h> + +#include <plat/platsmp.h> + +/* + * versatile_cpu_release controls the release of CPUs from the holding + * pen in headsmp.S, which exists because we are not always able to + * control the release of individual CPUs from the board firmware. + * Production platforms do not need this. + */ +volatile int versatile_cpu_release = -1; + +/* + * Write versatile_cpu_release in a way that is guaranteed to be visible to + * all observers, irrespective of whether they're taking part in coherency + * or not. This is necessary for the hotplug code to work reliably. + */ +static void versatile_write_cpu_release(int val) +{ + versatile_cpu_release = val; + smp_wmb(); + sync_cache_w(&versatile_cpu_release); +} + +/* + * versatile_lock exists to avoid running the loops_per_jiffy delay loop + * calibrations on the secondary CPU while the requesting CPU is using + * the limited-bandwidth bus - which affects the calibration value. + * Production platforms do not need this. + */ +static DEFINE_RAW_SPINLOCK(versatile_lock); + +void versatile_secondary_init(unsigned int cpu) +{ + /* + * let the primary processor know we're out of the + * pen, then head off into the C entry point + */ + versatile_write_cpu_release(-1); + + /* + * Synchronise with the boot thread. + */ + raw_spin_lock(&versatile_lock); + raw_spin_unlock(&versatile_lock); +} + +int versatile_boot_secondary(unsigned int cpu, struct task_struct *idle) +{ + unsigned long timeout; + + /* + * Set synchronisation state between this boot processor + * and the secondary one + */ + raw_spin_lock(&versatile_lock); + + /* + * This is really belt and braces; we hold unintended secondary + * CPUs in the holding pen until we're ready for them. However, + * since we haven't sent them a soft interrupt, they shouldn't + * be there. + */ + versatile_write_cpu_release(cpu_logical_map(cpu)); + + /* + * Send the secondary CPU a soft interrupt, thereby causing + * the boot monitor to read the system wide flags register, + * and branch to the address found there. + */ + arch_send_wakeup_ipi_mask(cpumask_of(cpu)); + + timeout = jiffies + (1 * HZ); + while (time_before(jiffies, timeout)) { + smp_rmb(); + if (versatile_cpu_release == -1) + break; + + udelay(10); + } + + /* + * now the secondary core is starting up let it run its + * calibrations, then wait for it to finish + */ + raw_spin_unlock(&versatile_lock); + + return versatile_cpu_release != -1 ? -ENOSYS : 0; +} |