1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * Pvpanic Device Support 4 * 5 * Copyright (C) 2013 Fujitsu. 6 * Copyright (C) 2018 ZTE. 7 * Copyright (C) 2021 Oracle. 8 */ 9 10#include <linux/device.h> 11#include <linux/errno.h> 12#include <linux/gfp_types.h> 13#include <linux/io.h> 14#include <linux/kexec.h> 15#include <linux/kstrtox.h> 16#include <linux/limits.h> 17#include <linux/list.h> 18#include <linux/mod_devicetable.h> 19#include <linux/module.h> 20#include <linux/panic_notifier.h> 21#include <linux/platform_device.h> 22#include <linux/spinlock.h> 23#include <linux/sysfs.h> 24#include <linux/types.h> 25 26#include <uapi/misc/pvpanic.h> 27 28#include "pvpanic.h" 29 30MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>"); 31MODULE_DESCRIPTION("pvpanic device driver"); 32MODULE_LICENSE("GPL"); 33 34struct pvpanic_instance { 35 void __iomem *base; 36 unsigned int capability; 37 unsigned int events; 38 struct list_head list; 39}; 40 41static struct list_head pvpanic_list; 42static spinlock_t pvpanic_lock; 43 44static void 45pvpanic_send_event(unsigned int event) 46{ 47 struct pvpanic_instance *pi_cur; 48 49 if (!spin_trylock(&pvpanic_lock)) 50 return; 51 52 list_for_each_entry(pi_cur, &pvpanic_list, list) { 53 if (event & pi_cur->capability & pi_cur->events) 54 iowrite8(event, pi_cur->base); 55 } 56 spin_unlock(&pvpanic_lock); 57} 58 59static int 60pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused) 61{ 62 unsigned int event = PVPANIC_PANICKED; 63 64 if (kexec_crash_loaded()) 65 event = PVPANIC_CRASH_LOADED; 66 67 pvpanic_send_event(event); 68 69 return NOTIFY_DONE; 70} 71 72/* 73 * Call our notifier very early on panic, deferring the 74 * action taken to the hypervisor. 75 */ 76static struct notifier_block pvpanic_panic_nb = { 77 .notifier_call = pvpanic_panic_notify, 78 .priority = INT_MAX, 79}; 80 81static void pvpanic_remove(void *param) 82{ 83 struct pvpanic_instance *pi_cur, *pi_next; 84 struct pvpanic_instance *pi = param; 85 86 spin_lock(&pvpanic_lock); 87 list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) { 88 if (pi_cur == pi) { 89 list_del(&pi_cur->list); 90 break; 91 } 92 } 93 spin_unlock(&pvpanic_lock); 94} 95 96static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf) 97{ 98 struct pvpanic_instance *pi = dev_get_drvdata(dev); 99 100 return sysfs_emit(buf, "%x\n", pi->capability); 101} 102static DEVICE_ATTR_RO(capability); 103 104static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf) 105{ 106 struct pvpanic_instance *pi = dev_get_drvdata(dev); 107 108 return sysfs_emit(buf, "%x\n", pi->events); 109} 110 111static ssize_t events_store(struct device *dev, struct device_attribute *attr, 112 const char *buf, size_t count) 113{ 114 struct pvpanic_instance *pi = dev_get_drvdata(dev); 115 unsigned int tmp; 116 int err; 117 118 err = kstrtouint(buf, 16, &tmp); 119 if (err) 120 return err; 121 122 if ((tmp & pi->capability) != tmp) 123 return -EINVAL; 124 125 pi->events = tmp; 126 127 return count; 128} 129static DEVICE_ATTR_RW(events); 130 131static struct attribute *pvpanic_dev_attrs[] = { 132 &dev_attr_capability.attr, 133 &dev_attr_events.attr, 134 NULL 135}; 136 137static const struct attribute_group pvpanic_dev_group = { 138 .attrs = pvpanic_dev_attrs, 139}; 140 141const struct attribute_group *pvpanic_dev_groups[] = { 142 &pvpanic_dev_group, 143 NULL 144}; 145EXPORT_SYMBOL_GPL(pvpanic_dev_groups); 146 147int devm_pvpanic_probe(struct device *dev, void __iomem *base) 148{ 149 struct pvpanic_instance *pi; 150 151 if (!base) 152 return -EINVAL; 153 154 pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL); 155 if (!pi) 156 return -ENOMEM; 157 158 pi->base = base; 159 pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED; 160 161 /* initlize capability by RDPT */ 162 pi->capability &= ioread8(base); 163 pi->events = pi->capability; 164 165 spin_lock(&pvpanic_lock); 166 list_add(&pi->list, &pvpanic_list); 167 spin_unlock(&pvpanic_lock); 168 169 dev_set_drvdata(dev, pi); 170 171 return devm_add_action_or_reset(dev, pvpanic_remove, pi); 172} 173EXPORT_SYMBOL_GPL(devm_pvpanic_probe); 174 175static int pvpanic_init(void) 176{ 177 INIT_LIST_HEAD(&pvpanic_list); 178 spin_lock_init(&pvpanic_lock); 179 180 atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb); 181 182 return 0; 183} 184module_init(pvpanic_init); 185 186static void pvpanic_exit(void) 187{ 188 atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb); 189 190} 191module_exit(pvpanic_exit); 192