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 an array of boot data
22 * to handle that.
23 */
24static struct sbi_hart_boot_data boot_data[NR_CPUS];
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 = &boot_data[cpuid];
71
72 /* Make sure tidle is updated */
73 smp_mb();
74 bdata->task_ptr = tidle;
75 bdata->stack_ptr = task_pt_regs(tidle);
76 /* Make sure boot data is updated */
77 smp_mb();
78 hsm_data = __pa(bdata);
79 return sbi_hsm_hart_start(hartid, saddr: boot_addr, priv: 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 %d (%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

source code of linux/arch/riscv/kernel/cpu_ops_sbi.c