1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ARM64 ACPI Parking Protocol implementation
  4 *
  5 * Authors: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
  6 *	    Mark Salter <msalter@redhat.com>
  7 */
  8#include <linux/acpi.h>
  9#include <linux/mm.h>
 10#include <linux/types.h>
 11
 12#include <asm/cpu_ops.h>
 13
 14struct parking_protocol_mailbox {
 15	__le32 cpu_id;
 16	__le32 reserved;
 17	__le64 entry_point;
 18};
 19
 20struct cpu_mailbox_entry {
 21	struct parking_protocol_mailbox __iomem *mailbox;
 22	phys_addr_t mailbox_addr;
 23	u8 version;
 24	u8 gic_cpu_id;
 25};
 26
 27static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
 28
 29void __init acpi_set_mailbox_entry(int cpu,
 30				   struct acpi_madt_generic_interrupt *p)
 31{
 32	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 33
 34	cpu_entry->mailbox_addr = p->parked_address;
 35	cpu_entry->version = p->parking_version;
 36	cpu_entry->gic_cpu_id = p->cpu_interface_number;
 37}
 38
 39bool acpi_parking_protocol_valid(int cpu)
 40{
 41	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 42
 43	return cpu_entry->mailbox_addr && cpu_entry->version;
 44}
 45
 46static int acpi_parking_protocol_cpu_init(unsigned int cpu)
 47{
 48	pr_debug("%s: ACPI parked addr=%llx\n", __func__,
 49		  cpu_mailbox_entries[cpu].mailbox_addr);
 50
 51	return 0;
 52}
 53
 54static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
 55{
 56	return 0;
 57}
 58
 59static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
 60{
 61	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 62	struct parking_protocol_mailbox __iomem *mailbox;
 63	u32 cpu_id;
 64
 65	/*
 66	 * Map mailbox memory with attribute device nGnRE (ie ioremap -
 67	 * this deviates from the parking protocol specifications since
 68	 * the mailboxes are required to be mapped nGnRnE; the attribute
 69	 * discrepancy is harmless insofar as the protocol specification
 70	 * is concerned).
 71	 * If the mailbox is mistakenly allocated in the linear mapping
 72	 * by FW ioremap will fail since the mapping will be prevented
 73	 * by the kernel (it clashes with the linear mapping attributes
 74	 * specifications).
 75	 */
 76	mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
 77	if (!mailbox)
 78		return -EIO;
 79
 80	cpu_id = readl_relaxed(&mailbox->cpu_id);
 81	/*
 82	 * Check if firmware has set-up the mailbox entry properly
 83	 * before kickstarting the respective cpu.
 84	 */
 85	if (cpu_id != ~0U) {
 86		iounmap(mailbox);
 87		return -ENXIO;
 88	}
 89
 90	/*
 91	 * stash the mailbox address mapping to use it for further FW
 92	 * checks in the postboot method
 93	 */
 94	cpu_entry->mailbox = mailbox;
 95
 96	/*
 97	 * We write the entry point and cpu id as LE regardless of the
 98	 * native endianness of the kernel. Therefore, any boot-loaders
 99	 * that read this address need to convert this address to the
100	 * Boot-Loader's endianness before jumping.
101	 */
102	writeq_relaxed(__pa_symbol(secondary_entry),
103		       &mailbox->entry_point);
104	writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
105
106	arch_send_wakeup_ipi(cpu);
107
108	return 0;
109}
110
111static void acpi_parking_protocol_cpu_postboot(void)
112{
113	int cpu = smp_processor_id();
114	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
115	struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
116	u64 entry_point;
117
118	entry_point = readq_relaxed(&mailbox->entry_point);
119	/*
120	 * Check if firmware has cleared the entry_point as expected
121	 * by the protocol specification.
122	 */
123	WARN_ON(entry_point);
124}
125
126const struct cpu_operations acpi_parking_protocol_ops = {
127	.name		= "parking-protocol",
128	.cpu_init	= acpi_parking_protocol_cpu_init,
129	.cpu_prepare	= acpi_parking_protocol_cpu_prepare,
130	.cpu_boot	= acpi_parking_protocol_cpu_boot,
131	.cpu_postboot	= acpi_parking_protocol_cpu_postboot
132};