diff options
Diffstat (limited to 'arch/arm64/kernel/smp_spin_table.c')
-rw-r--r-- | arch/arm64/kernel/smp_spin_table.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c new file mode 100644 index 000000000..49029eace --- /dev/null +++ b/arch/arm64/kernel/smp_spin_table.c @@ -0,0 +1,127 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Spin Table SMP initialisation + * + * Copyright (C) 2013 ARM Ltd. + */ + +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/of.h> +#include <linux/smp.h> +#include <linux/types.h> +#include <linux/mm.h> + +#include <asm/cacheflush.h> +#include <asm/cpu_ops.h> +#include <asm/cputype.h> +#include <asm/io.h> +#include <asm/smp_plat.h> + +extern void secondary_holding_pen(void); +volatile unsigned long __section(".mmuoff.data.read") +secondary_holding_pen_release = INVALID_HWID; + +static phys_addr_t cpu_release_addr[NR_CPUS]; + +/* + * Write secondary_holding_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 write_pen_release(u64 val) +{ + void *start = (void *)&secondary_holding_pen_release; + unsigned long size = sizeof(secondary_holding_pen_release); + + secondary_holding_pen_release = val; + dcache_clean_inval_poc((unsigned long)start, (unsigned long)start + size); +} + + +static int smp_spin_table_cpu_init(unsigned int cpu) +{ + struct device_node *dn; + int ret; + + dn = of_get_cpu_node(cpu, NULL); + if (!dn) + return -ENODEV; + + /* + * Determine the address from which the CPU is polling. + */ + ret = of_property_read_u64(dn, "cpu-release-addr", + &cpu_release_addr[cpu]); + if (ret) + pr_err("CPU %d: missing or invalid cpu-release-addr property\n", + cpu); + + of_node_put(dn); + + return ret; +} + +static int smp_spin_table_cpu_prepare(unsigned int cpu) +{ + __le64 __iomem *release_addr; + phys_addr_t pa_holding_pen = __pa_symbol(secondary_holding_pen); + + if (!cpu_release_addr[cpu]) + return -ENODEV; + + /* + * The cpu-release-addr may or may not be inside the linear mapping. + * As ioremap_cache will either give us a new mapping or reuse the + * existing linear mapping, we can use it to cover both cases. In + * either case the memory will be MT_NORMAL. + */ + release_addr = ioremap_cache(cpu_release_addr[cpu], + sizeof(*release_addr)); + if (!release_addr) + return -ENOMEM; + + /* + * We write the release address as LE regardless of the native + * endianness of the kernel. Therefore, any boot-loaders that + * read this address need to convert this address to the + * boot-loader's endianness before jumping. This is mandated by + * the boot protocol. + */ + writeq_relaxed(pa_holding_pen, release_addr); + dcache_clean_inval_poc((__force unsigned long)release_addr, + (__force unsigned long)release_addr + + sizeof(*release_addr)); + + /* + * Send an event to wake up the secondary CPU. + */ + sev(); + + iounmap(release_addr); + + return 0; +} + +static int smp_spin_table_cpu_boot(unsigned int cpu) +{ + /* + * Update the pen release flag. + */ + write_pen_release(cpu_logical_map(cpu)); + + /* + * Send an event, causing the secondaries to read pen_release. + */ + sev(); + + return 0; +} + +const struct cpu_operations smp_spin_table_ops = { + .name = "spin-table", + .cpu_init = smp_spin_table_cpu_init, + .cpu_prepare = smp_spin_table_cpu_prepare, + .cpu_boot = smp_spin_table_cpu_boot, +}; |