From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- arch/arm/mach-spear/platsmp.c | 133 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 arch/arm/mach-spear/platsmp.c (limited to 'arch/arm/mach-spear/platsmp.c') diff --git a/arch/arm/mach-spear/platsmp.c b/arch/arm/mach-spear/platsmp.c new file mode 100644 index 0000000000..97fbda998d --- /dev/null +++ b/arch/arm/mach-spear/platsmp.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * arch/arm/mach-spear13xx/platsmp.c + * + * based upon linux/arch/arm/mach-realview/platsmp.c + * + * Copyright (C) 2012 ST Microelectronics Ltd. + * Shiraz Hashim + */ + +#include +#include +#include +#include +#include +#include +#include "spear.h" +#include "generic.h" + +/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */ +volatile int spear_pen_release = -1; + +/* + * XXX CARGO CULTED CODE - DO NOT COPY XXX + * + * Write spear_pen_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 spear_write_pen_release(int val) +{ + spear_pen_release = val; + smp_wmb(); + sync_cache_w(&spear_pen_release); +} + +static DEFINE_SPINLOCK(boot_lock); + +static void __iomem *scu_base = IOMEM(VA_SCU_BASE); + +static void spear13xx_secondary_init(unsigned int cpu) +{ + /* + * let the primary processor know we're out of the + * pen, then head off into the C entry point + */ + spear_write_pen_release(-1); + + /* + * Synchronise with the boot thread. + */ + spin_lock(&boot_lock); + spin_unlock(&boot_lock); +} + +static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) +{ + unsigned long timeout; + + /* + * set synchronisation state between this boot processor + * and the secondary one + */ + spin_lock(&boot_lock); + + /* + * The secondary processor is waiting to be released from + * the holding pen - release it, then wait for it to flag + * that it has been released by resetting spear_pen_release. + * + * Note that "spear_pen_release" is the hardware CPU ID, whereas + * "cpu" is Linux's internal ID. + */ + spear_write_pen_release(cpu); + + timeout = jiffies + (1 * HZ); + while (time_before(jiffies, timeout)) { + smp_rmb(); + if (spear_pen_release == -1) + break; + + udelay(10); + } + + /* + * now the secondary core is starting up let it run its + * calibrations, then wait for it to finish + */ + spin_unlock(&boot_lock); + + return spear_pen_release != -1 ? -ENOSYS : 0; +} + +/* + * Initialise the CPU possible map early - this describes the CPUs + * which may be present or become present in the system. + */ +static void __init spear13xx_smp_init_cpus(void) +{ + unsigned int i, ncores = scu_get_core_count(scu_base); + + if (ncores > nr_cpu_ids) { + pr_warn("SMP: %u cores greater than maximum (%u), clipping\n", + ncores, nr_cpu_ids); + ncores = nr_cpu_ids; + } + + for (i = 0; i < ncores; i++) + set_cpu_possible(i, true); +} + +static void __init spear13xx_smp_prepare_cpus(unsigned int max_cpus) +{ + + scu_enable(scu_base); + + /* + * Write the address of secondary startup into the system-wide location + * (presently it is in SRAM). The BootMonitor waits until it receives a + * soft interrupt, and then the secondary CPU branches to this address. + */ + __raw_writel(__pa_symbol(spear13xx_secondary_startup), SYS_LOCATION); +} + +const struct smp_operations spear13xx_smp_ops __initconst = { + .smp_init_cpus = spear13xx_smp_init_cpus, + .smp_prepare_cpus = spear13xx_smp_prepare_cpus, + .smp_secondary_init = spear13xx_secondary_init, + .smp_boot_secondary = spear13xx_boot_secondary, +#ifdef CONFIG_HOTPLUG_CPU + .cpu_die = spear13xx_cpu_die, +#endif +}; -- cgit v1.2.3