diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/psci.h | 37 | ||||
| -rw-r--r-- | arch/arm64/kernel/start.S | 78 | ||||
| -rw-r--r-- | arch/arm64/lib/cache_va.c | 73 | ||||
| -rw-r--r-- | arch/arm64/lib/psci.c | 118 | ||||
| -rw-r--r-- | arch/arm64/lib/system.c | 46 | ||||
| -rw-r--r-- | arch/arm64/lib/timer.c | 48 |
6 files changed, 399 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h new file mode 100644 index 0000000..d7ce0f3 --- /dev/null +++ b/arch/arm64/include/asm/psci.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_PSCI_H +#define __ASM_PSCI_H + +#include <stdint.h> +/* + * PSCI 0.2 handler at EL2, the Power State Coordination Interface + * per DEN 0022. the payload calls it through the conduit the dtb + * names, hvc here, the call traps to EL2 and this dispatches. + */ + +/* standard function ids, DEN 0022 table 5-1 */ +#define PSCI_FN_VERSION 0x84000000 +#define PSCI_FN_CPU_OFF 0x84000002 +#define PSCI_FN_CPU_ON 0x84000003 +#define PSCI_FN_SYSTEM_OFF 0x84000008 +#define PSCI_FN_SYSTEM_RESET 0x84000009 + +/* version 0.2, major 0 minor 2 */ +#define PSCI_VERSION_0_2 0x00000002 + +/* error codes, DEN 0022 */ +#define PSCI_RET_SUCCESS 0 +#define PSCI_RET_NOT_SUPPORTED -1 +#define PSCI_RET_INVALID_PARAMS -2 +#define PSCI_RET_DENIED -3 +#define PSCI_RET_ALREADY_ON -4 +#define PSCI_RET_ON_PENDING -5 +#define PSCI_RET_INTERNAL_FAIL -6 +#define PSCI_RET_NOT_PRESENT -7 +#define PSCI_RET_DISABLED -8 + +/* the asm HVC vector calls this with the caller's x0-x3 in place */ +uint64_t tb_psci_dispatch(uint64_t fn, uint64_t x1, uint64_t x2, + uint64_t x3); + +#endif /* __ASM_PSCI_H */ diff --git a/arch/arm64/kernel/start.S b/arch/arm64/kernel/start.S index 2d4b5c0..969830d 100644 --- a/arch/arm64/kernel/start.S +++ b/arch/arm64/kernel/start.S @@ -147,6 +147,11 @@ c_entry: ldr x0, =__stack_top mov sp, x0 + /* export the spin gate array address for the dtb patcher */ + adr x0, tb_spin_gates + adrp x1, tb_spin_gates_ptr + str x0, [x1, #:lo12:tb_spin_gates_ptr] + /* clear bss */ ldr x0, =__bss_start ldr x1, =__bss_end @@ -166,9 +171,44 @@ c_entry: bl tashaboot_main /* if main returns there is nothing sensible to do */ +/* + * the spin table pen, the Wait For Event mechanism from the manual + * (B2-144, D1-2255). each secondary watches its own gate, the + * cpu-release-addr the dtb names. WFE clears the event register and + * sleeps, the kernel writes the secondary entry to the gate, makes + * it visible, then SEV sets the event register on every PE. the load + * recheck after each wake covers a release that lands between the + * load and the WFE. entered with MMU and caches off, left the same. + */ +.globl park_ret +park_ret: park: + adr x0, tb_spin_gates + mrs x1, mpidr_el1 + and x1, x1, #0xff /* affinity 0, the core number */ + add x0, x0, x1, lsl #3 /* gate = gates + core * 8 */ + + /* diagnostic: stamp arrival, primary prints it later */ + adr x3, tb_pen_stamps + strb w1, [x3, x1] + sevl wfe - b park + sevl + wfe + +1: + ldr x2, [x0] + cbnz x2, 2f + wfe + b 1b +2: + mov x0, xzr /* secondaries enter with x0-x3 zero */ + mov x1, xzr + mov x2, xzr + mov x3, xzr + dsb sy + isb + br x2 /* * exception vectors, the armv8 layout: 16 slots, 128 bytes each, in @@ -218,6 +258,19 @@ vectors: .align 7 b exc_serr +.pushsection .data.tb_spin, "aw" +.align 3 +.globl tb_spin_gates +tb_spin_gates: + .quad 0, 0, 0, 0, 0, 0, 0, 0 +.globl tb_spin_gates_ptr +tb_spin_gates_ptr: + .quad 0 +.globl tb_pen_stamps +tb_pen_stamps: + .byte 0, 0, 0, 0, 0, 0, 0, 0 +.popsection + exc_sync: stp x29, x30, [sp, #-16]! mov x29, sp @@ -226,6 +279,10 @@ exc_sync: cmp x3, #2 b.lt 1f mrs x0, esr_el2 + mrs x2, elr_el2 + lsr x1, x0, #26 + cmp x1, #0x16 /* HVC from lower EL */ + b.eq hvc_from_el1 mrs x1, far_el2 b 2f 1: @@ -237,6 +294,25 @@ exc_sync: ldp x29, x30, [sp], #16 b park +/* + * HVC from EL1, the PSCI conduit. x0-x3 are the PSCI args in the + * caller registers, dispatch and return in x0. ELR_EL2 is already + * the resume point, eret takes it back. + */ +hvc_from_el1: + stp x4, x5, [sp, #-16]! + stp x6, x7, [sp, #-16]! + stp x29, x30, [sp, #-16]! + mov x29, sp + + bl tb_psci_dispatch + + ldp x29, x30, [sp], #16 + ldp x6, x7, [sp], #16 + ldp x4, x5, [sp], #16 + ldp x29, x30, [sp], #16 + eret + exc_serr: stp x29, x30, [sp, #-16]! mov x29, sp diff --git a/arch/arm64/lib/cache_va.c b/arch/arm64/lib/cache_va.c new file mode 100644 index 0000000..1fd7804 --- /dev/null +++ b/arch/arm64/lib/cache_va.c @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * cache_va.c - cache maintenance by virtual address, the operations + * the manual prescribes for boot handoff: clean to point of + * coherency (dc cvac), invalidate (dc ivac), and clean and + * invalidate (dc civac), plus icache invalidate by VA to the point + * of unification (ic ivau). by VA beats by set and way when the + * address range is known, the manual's own guidance, set and way + * only for the full flush cases in cache.S. + * + * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org> + */ + +#include <stdint.h> +#include <sys/types.h> + +#define CACHE_LINE_SHIFT 6 /* 64 byte lines on cortex-a class */ +#define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT) + +void tb_clean_dcache_range(uintptr_t start, size_t len) +{ + uintptr_t line = start & ~(uintptr_t)(CACHE_LINE_SIZE - 1); + uintptr_t end = start + len; + + while (line < end) { + asm volatile("dc cvac, %0" :: "r" (line) : "memory"); + line += CACHE_LINE_SIZE; + } + + asm volatile("dsb sy" ::: "memory"); +} + +void tb_inval_dcache_range(uintptr_t start, size_t len) +{ + uintptr_t line = start & ~(uintptr_t)(CACHE_LINE_SIZE - 1); + uintptr_t end = start + len; + + while (line < end) { + asm volatile("dc ivac, %0" :: "r" (line) : "memory"); + line += CACHE_LINE_SIZE; + } + + asm volatile("dsb sy" ::: "memory"); +} + +void tb_clean_inval_dcache_range(uintptr_t start, size_t len) +{ + uintptr_t line = start & ~(uintptr_t)(CACHE_LINE_SIZE - 1); + uintptr_t end = start + len; + + while (line < end) { + asm volatile("dc civac, %0" :: "r" (line) : "memory"); + line += CACHE_LINE_SIZE; + } + + asm volatile("dsb sy" ::: "memory"); +} + +void tb_inval_icache_range(uintptr_t start, size_t len) +{ + uintptr_t line = start & ~(uintptr_t)(CACHE_LINE_SIZE - 1); + uintptr_t end = start + len; + + while (line < end) { + asm volatile("ic ivau, %0" :: "r" (line) : "memory"); + line += CACHE_LINE_SIZE; + } + + asm volatile( + "dsb ish\n" + "isb\n" + ::: "memory"); +} diff --git a/arch/arm64/lib/psci.c b/arch/arm64/lib/psci.c new file mode 100644 index 0000000..ad5f461 --- /dev/null +++ b/arch/arm64/lib/psci.c @@ -0,0 +1,118 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * psci.c - PSCI 0.2 at EL2, the calls a payload makes to control + * cores and the system, per DEN 0022. the call arrives as an HVC + * trap at EL2 (EC 0x16), x0 holds the function id, x1 to x3 the + * arguments, the return value goes back in x0 and eret resumes the + * caller at EL1. + * + * CPU_ON writes the spin gate of the target core and SEVs, the pen + * from start.S does the release. CPU_OFF parks the calling core. + * SYSTEM_OFF and SYSTEM_RESET drive the architecture reset domain. + * + * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org> + */ + +#include <asm/psci.h> +#include <debug.h> + +extern void tb_system_reset(void); +extern void tb_system_off(void); + +/* the gates and stamps from start.S, one per possible core */ +extern unsigned long tb_spin_gates[8]; +extern unsigned char tb_pen_stamps[8]; + +static uint64_t psci_cpu_on(uint64_t target, uint64_t entry, + uint64_t ctx) +{ + unsigned long mpidr; + int cpu; + + /* affinity 0 only, our gate array indexes cores 0..7 */ + if (target > 7) + return PSCI_RET_INVALID_PARAMS; + + asm volatile("mrs %0, mpidr_el1" : "=r" (mpidr)); + if ((mpidr & 0xff) == target) + return PSCI_RET_ALREADY_ON; + + cpu = (int)target; + + /* + * the pen saves no context, CPU_ON per DEN 0022 passes an + * entry and a context id. the pen enters with x0 = ctx, the + * kernel secondary entry takes x0 as its context pointer. + * the gate holds the entry, the stamp array the ctx. + */ + tb_spin_gates[cpu] = entry; + tb_pen_stamps[cpu] = (unsigned char)(ctx & 0xff); + + /* make the gate write visible before the wake, D1-2255 */ + asm volatile("dsb sy"); + asm volatile("sev"); + + dprintf(ALWAYS, "psci: cpu_on %llu -> %llx\n", + (unsigned long long)target, + (unsigned long long)entry); + + return PSCI_RET_SUCCESS; +} + +extern void park_ret(void); + +static uint64_t psci_cpu_off(void) +{ + unsigned long mpidr; + int cpu; + + asm volatile("mrs %0, mpidr_el1" : "=r" (mpidr)); + cpu = (int)(mpidr & 0xff); + + if (cpu > 7) + return PSCI_RET_NOT_SUPPORTED; + + /* clear our own gate and go back to the pen */ + tb_spin_gates[cpu] = 0; + + dprintf(ALWAYS, "psci: cpu_off %d\n", cpu); + + asm volatile( + "dsb sy\n" + "b park_ret\n" + ); + + return PSCI_RET_INTERNAL_FAIL; /* not reached */ +} + +/* + * the asm vector calls this with the caller x0-x3 still in place, + * function id in x0, arguments in x1-x3, the return lands in x0. + */ +uint64_t tb_psci_dispatch(uint64_t fn, uint64_t x1, uint64_t x2, + uint64_t x3) +{ + switch (fn) { + case PSCI_FN_VERSION: + return PSCI_VERSION_0_2; + + case PSCI_FN_CPU_ON: + return psci_cpu_on(x1, x2, x3); + + case PSCI_FN_CPU_OFF: + return psci_cpu_off(); + + case PSCI_FN_SYSTEM_OFF: + dprintf(ALWAYS, "psci: system off\n"); + tb_system_off(); + return PSCI_RET_SUCCESS; + + case PSCI_FN_SYSTEM_RESET: + dprintf(ALWAYS, "psci: system reset\n"); + tb_system_reset(); + return PSCI_RET_INTERNAL_FAIL; /* not reached */ + + default: + return PSCI_RET_NOT_SUPPORTED; + } +} diff --git a/arch/arm64/lib/system.c b/arch/arm64/lib/system.c new file mode 100644 index 0000000..4e227f6 --- /dev/null +++ b/arch/arm64/lib/system.c @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * system.c - system power control, the PSCI SYSTEM_OFF and + * SYSTEM_RESET backends. off parks the core in WFI forever, the + * manual's low power entry (D1-2255). reset drives the PE reset + * domain: RMR_EL2 reset request with the system reset bit, RR bit 1, + * followed by a barrier pair so the request retires before anything + * else observes the core. + * + * On real hardware a SoC also needs a watchdog or PMIC write for a + * full board reset, that is board territory, the arch part is this. + * + * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org> + */ + +#include <debug.h> +#include <stdint.h> + +void tb_system_off(void) +{ + dprintf(ALWAYS, "system off\n"); + + for (;;) { + asm volatile("wfi"); + } +} + +void tb_system_reset(void) +{ + uint64_t rmr; + + dprintf(ALWAYS, "system reset\n"); + + asm volatile("mrs %0, rmr_el2" : "=r" (rmr)); + rmr |= (1 << 1); /* RR, request reset */ + asm volatile( + "msr rmr_el2, %0\n" + "dsb sy\n" + "isb\n" + :: "r" (rmr)); + + /* if the reset domain ignores us, park */ + for (;;) { + asm volatile("wfi"); + } +} diff --git a/arch/arm64/lib/timer.c b/arch/arm64/lib/timer.c new file mode 100644 index 0000000..605cd18 --- /dev/null +++ b/arch/arm64/lib/timer.c @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * timer.c - generic timer delays, the system counter from D10. the + * counter is a fixed frequency free running counter, CNTFRQ_EL0 + * carries the frequency, CNTVCT_EL0 the 64 bit count. delays are a + * busy wait on the counter, no interrupts needed, microsecond and + * millisecond granularity. + * + * CNTVCT_EL0 is the virtual counter view; at EL2 with no offset + * configured it is the physical count. the read is not speculative + * and needs an isb to serialize against subsequent counter reads + * per the counter access rules. + * + * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org> + */ + +#include <stdint.h> + +static uint64_t read_cntfrq(void) +{ + uint64_t v; + + asm volatile("mrs %0, cntfrq_el0" : "=r" (v)); + return v; +} + +static uint64_t read_counter(void) +{ + uint64_t v; + + asm volatile("isb\nmrs %0, cntvct_el0" : "=r" (v)); + return v; +} + +void tb_udelay(uint32_t us) +{ + uint64_t freq = read_cntfrq(); + uint64_t start = read_counter(); + uint64_t ticks = (uint64_t)us * freq / 1000000ULL; + + while (read_counter() - start < ticks) + ; +} + +void tb_mdelay(uint32_t ms) +{ + tb_udelay(ms * 1000); +} |