1 /*
2  * ARM64 ACPI Parking Protocol implementation
3  *
4  * Authors: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
5  *	    Mark Salter <msalter@redhat.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 #include <linux/acpi.h>
20 #include <linux/types.h>
21 
22 #include <asm/cpu_ops.h>
23 
24 struct parking_protocol_mailbox {
25 	__le32 cpu_id;
26 	__le32 reserved;
27 	__le64 entry_point;
28 };
29 
30 struct cpu_mailbox_entry {
31 	struct parking_protocol_mailbox __iomem *mailbox;
32 	phys_addr_t mailbox_addr;
33 	u8 version;
34 	u8 gic_cpu_id;
35 };
36 
37 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
38 
39 void __init acpi_set_mailbox_entry(int cpu,
40 				   struct acpi_madt_generic_interrupt *p)
41 {
42 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
43 
44 	cpu_entry->mailbox_addr = p->parked_address;
45 	cpu_entry->version = p->parking_version;
46 	cpu_entry->gic_cpu_id = p->cpu_interface_number;
47 }
48 
49 bool acpi_parking_protocol_valid(int cpu)
50 {
51 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
52 
53 	return cpu_entry->mailbox_addr && cpu_entry->version;
54 }
55 
56 static int acpi_parking_protocol_cpu_init(unsigned int cpu)
57 {
58 	pr_debug("%s: ACPI parked addr=%llx\n", __func__,
59 		  cpu_mailbox_entries[cpu].mailbox_addr);
60 
61 	return 0;
62 }
63 
64 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
65 {
66 	return 0;
67 }
68 
69 static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
70 {
71 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
72 	struct parking_protocol_mailbox __iomem *mailbox;
73 	__le32 cpu_id;
74 
75 	/*
76 	 * Map mailbox memory with attribute device nGnRE (ie ioremap -
77 	 * this deviates from the parking protocol specifications since
78 	 * the mailboxes are required to be mapped nGnRnE; the attribute
79 	 * discrepancy is harmless insofar as the protocol specification
80 	 * is concerned).
81 	 * If the mailbox is mistakenly allocated in the linear mapping
82 	 * by FW ioremap will fail since the mapping will be prevented
83 	 * by the kernel (it clashes with the linear mapping attributes
84 	 * specifications).
85 	 */
86 	mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
87 	if (!mailbox)
88 		return -EIO;
89 
90 	cpu_id = readl_relaxed(&mailbox->cpu_id);
91 	/*
92 	 * Check if firmware has set-up the mailbox entry properly
93 	 * before kickstarting the respective cpu.
94 	 */
95 	if (cpu_id != ~0U) {
96 		iounmap(mailbox);
97 		return -ENXIO;
98 	}
99 
100 	/*
101 	 * stash the mailbox address mapping to use it for further FW
102 	 * checks in the postboot method
103 	 */
104 	cpu_entry->mailbox = mailbox;
105 
106 	/*
107 	 * We write the entry point and cpu id as LE regardless of the
108 	 * native endianness of the kernel. Therefore, any boot-loaders
109 	 * that read this address need to convert this address to the
110 	 * Boot-Loader's endianness before jumping.
111 	 */
112 	writeq_relaxed(__pa(secondary_entry), &mailbox->entry_point);
113 	writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
114 
115 	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
116 
117 	return 0;
118 }
119 
120 static void acpi_parking_protocol_cpu_postboot(void)
121 {
122 	int cpu = smp_processor_id();
123 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
124 	struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
125 	__le64 entry_point;
126 
127 	entry_point = readl_relaxed(&mailbox->entry_point);
128 	/*
129 	 * Check if firmware has cleared the entry_point as expected
130 	 * by the protocol specification.
131 	 */
132 	WARN_ON(entry_point);
133 }
134 
135 const struct cpu_operations acpi_parking_protocol_ops = {
136 	.name		= "parking-protocol",
137 	.cpu_init	= acpi_parking_protocol_cpu_init,
138 	.cpu_prepare	= acpi_parking_protocol_cpu_prepare,
139 	.cpu_boot	= acpi_parking_protocol_cpu_boot,
140 	.cpu_postboot	= acpi_parking_protocol_cpu_postboot
141 };
142