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