1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * HSM extension and cpu_ops implementation.
4 *
5 * Copyright (c) 2020 Western Digital Corporation or its affiliates.
6 */
7
8#include <linux/init.h>
9#include <linux/mm.h>
10#include <linux/sched/task_stack.h>
11#include <asm/cpu_ops.h>
12#include <asm/cpu_ops_sbi.h>
13#include <asm/sbi.h>
14#include <asm/smp.h>
15
16extern char secondary_start_sbi[];
17const struct cpu_operations cpu_ops_sbi;
18
19/*
20 * Ordered booting via HSM brings one cpu at a time. However, cpu hotplug can
21 * be invoked from multiple threads in parallel. Define a per cpu data
22 * to handle that.
23 */
24static DEFINE_PER_CPU(struct sbi_hart_boot_data, boot_data);
25
26static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
27			      unsigned long priv)
28{
29	struct sbiret ret;
30
31	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
32			hartid, saddr, priv, 0, 0, 0);
33	if (ret.error)
34		return sbi_err_map_linux_errno(ret.error);
35	else
36		return 0;
37}
38
39#ifdef CONFIG_HOTPLUG_CPU
40static int sbi_hsm_hart_stop(void)
41{
42	struct sbiret ret;
43
44	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
45
46	if (ret.error)
47		return sbi_err_map_linux_errno(ret.error);
48	else
49		return 0;
50}
51
52static int sbi_hsm_hart_get_status(unsigned long hartid)
53{
54	struct sbiret ret;
55
56	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
57			hartid, 0, 0, 0, 0, 0);
58	if (ret.error)
59		return sbi_err_map_linux_errno(ret.error);
60	else
61		return ret.value;
62}
63#endif
64
65static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
66{
67	unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
68	unsigned long hartid = cpuid_to_hartid_map(cpuid);
69	unsigned long hsm_data;
70	struct sbi_hart_boot_data *bdata = &per_cpu(boot_data, cpuid);
71
72	/* Make sure tidle is updated */
73	smp_mb();
74	bdata->task_ptr = tidle;
75	bdata->stack_ptr = task_stack_page(tidle) + THREAD_SIZE;
76	/* Make sure boot data is updated */
77	smp_mb();
78	hsm_data = __pa(bdata);
79	return sbi_hsm_hart_start(hartid, boot_addr, hsm_data);
80}
81
82#ifdef CONFIG_HOTPLUG_CPU
83static void sbi_cpu_stop(void)
84{
85	int ret;
86
87	ret = sbi_hsm_hart_stop();
88	pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);
89}
90
91static int sbi_cpu_is_stopped(unsigned int cpuid)
92{
93	int rc;
94	unsigned long hartid = cpuid_to_hartid_map(cpuid);
95
96	rc = sbi_hsm_hart_get_status(hartid);
97
98	if (rc == SBI_HSM_STATE_STOPPED)
99		return 0;
100	return rc;
101}
102#endif
103
104const struct cpu_operations cpu_ops_sbi = {
105	.cpu_start	= sbi_cpu_start,
106#ifdef CONFIG_HOTPLUG_CPU
107	.cpu_stop	= sbi_cpu_stop,
108	.cpu_is_stopped	= sbi_cpu_is_stopped,
109#endif
110};
111