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/mm.h>
21 #include <linux/types.h>
22 
23 #include <asm/cpu_ops.h>
24 
25 struct parking_protocol_mailbox {
26 	__le32 cpu_id;
27 	__le32 reserved;
28 	__le64 entry_point;
29 };
30 
31 struct cpu_mailbox_entry {
32 	struct parking_protocol_mailbox __iomem *mailbox;
33 	phys_addr_t mailbox_addr;
34 	u8 version;
35 	u8 gic_cpu_id;
36 };
37 
38 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
39 
40 void __init acpi_set_mailbox_entry(int cpu,
41 				   struct acpi_madt_generic_interrupt *p)
42 {
43 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
44 
45 	cpu_entry->mailbox_addr = p->parked_address;
46 	cpu_entry->version = p->parking_version;
47 	cpu_entry->gic_cpu_id = p->cpu_interface_number;
48 }
49 
50 bool acpi_parking_protocol_valid(int cpu)
51 {
52 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
53 
54 	return cpu_entry->mailbox_addr && cpu_entry->version;
55 }
56 
57 static int acpi_parking_protocol_cpu_init(unsigned int cpu)
58 {
59 	pr_debug("%s: ACPI parked addr=%llx\n", __func__,
60 		  cpu_mailbox_entries[cpu].mailbox_addr);
61 
62 	return 0;
63 }
64 
65 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
66 {
67 	return 0;
68 }
69 
70 static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
71 {
72 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
73 	struct parking_protocol_mailbox __iomem *mailbox;
74 	u32 cpu_id;
75 
76 	/*
77 	 * Map mailbox memory with attribute device nGnRE (ie ioremap -
78 	 * this deviates from the parking protocol specifications since
79 	 * the mailboxes are required to be mapped nGnRnE; the attribute
80 	 * discrepancy is harmless insofar as the protocol specification
81 	 * is concerned).
82 	 * If the mailbox is mistakenly allocated in the linear mapping
83 	 * by FW ioremap will fail since the mapping will be prevented
84 	 * by the kernel (it clashes with the linear mapping attributes
85 	 * specifications).
86 	 */
87 	mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
88 	if (!mailbox)
89 		return -EIO;
90 
91 	cpu_id = readl_relaxed(&mailbox->cpu_id);
92 	/*
93 	 * Check if firmware has set-up the mailbox entry properly
94 	 * before kickstarting the respective cpu.
95 	 */
96 	if (cpu_id != ~0U) {
97 		iounmap(mailbox);
98 		return -ENXIO;
99 	}
100 
101 	/*
102 	 * stash the mailbox address mapping to use it for further FW
103 	 * checks in the postboot method
104 	 */
105 	cpu_entry->mailbox = mailbox;
106 
107 	/*
108 	 * We write the entry point and cpu id as LE regardless of the
109 	 * native endianness of the kernel. Therefore, any boot-loaders
110 	 * that read this address need to convert this address to the
111 	 * Boot-Loader's endianness before jumping.
112 	 */
113 	writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point);
114 	writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
115 
116 	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
117 
118 	return 0;
119 }
120 
121 static void acpi_parking_protocol_cpu_postboot(void)
122 {
123 	int cpu = smp_processor_id();
124 	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
125 	struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
126 	u64 entry_point;
127 
128 	entry_point = readq_relaxed(&mailbox->entry_point);
129 	/*
130 	 * Check if firmware has cleared the entry_point as expected
131 	 * by the protocol specification.
132 	 */
133 	WARN_ON(entry_point);
134 }
135 
136 const struct cpu_operations acpi_parking_protocol_ops = {
137 	.name		= "parking-protocol",
138 	.cpu_init	= acpi_parking_protocol_cpu_init,
139 	.cpu_prepare	= acpi_parking_protocol_cpu_prepare,
140 	.cpu_boot	= acpi_parking_protocol_cpu_boot,
141 	.cpu_postboot	= acpi_parking_protocol_cpu_postboot
142 };
143