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
 82static int sbi_cpu_prepare(unsigned int cpuid)
 83{
 84	if (!cpu_ops_sbi.cpu_start) {
 85		pr_err("cpu start method not defined for CPU [%d]\n", cpuid);
 86		return -ENODEV;
 87	}
 88	return 0;
 89}
 90
 91#ifdef CONFIG_HOTPLUG_CPU
 92static int sbi_cpu_disable(unsigned int cpuid)
 93{
 94	if (!cpu_ops_sbi.cpu_stop)
 95		return -EOPNOTSUPP;
 96	return 0;
 97}
 98
 99static void sbi_cpu_stop(void)
100{
101	int ret;
102
103	ret = sbi_hsm_hart_stop();
104	pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);
105}
106
107static int sbi_cpu_is_stopped(unsigned int cpuid)
108{
109	int rc;
110	unsigned long hartid = cpuid_to_hartid_map(cpuid);
111
112	rc = sbi_hsm_hart_get_status(hartid);
113
114	if (rc == SBI_HSM_STATE_STOPPED)
115		return 0;
116	return rc;
117}
118#endif
119
120const struct cpu_operations cpu_ops_sbi = {
121	.name		= "sbi",
122	.cpu_prepare	= sbi_cpu_prepare,
123	.cpu_start	= sbi_cpu_start,
124#ifdef CONFIG_HOTPLUG_CPU
125	.cpu_disable	= sbi_cpu_disable,
126	.cpu_stop	= sbi_cpu_stop,
127	.cpu_is_stopped	= sbi_cpu_is_stopped,
128#endif
129};