1 /* 2 * nvs.c - Routines for saving and restoring ACPI NVS memory region 3 * 4 * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc. 5 * 6 * This file is released under the GPLv2. 7 */ 8 9 #include <linux/io.h> 10 #include <linux/kernel.h> 11 #include <linux/list.h> 12 #include <linux/mm.h> 13 #include <linux/slab.h> 14 #include <linux/acpi.h> 15 #include <linux/acpi_io.h> 16 #include <acpi/acpiosxf.h> 17 18 /* 19 * Platforms, like ACPI, may want us to save some memory used by them during 20 * suspend and to restore the contents of this memory during the subsequent 21 * resume. The code below implements a mechanism allowing us to do that. 22 */ 23 24 struct nvs_page { 25 unsigned long phys_start; 26 unsigned int size; 27 void *kaddr; 28 void *data; 29 bool unmap; 30 struct list_head node; 31 }; 32 33 static LIST_HEAD(nvs_list); 34 35 /** 36 * suspend_nvs_register - register platform NVS memory region to save 37 * @start - physical address of the region 38 * @size - size of the region 39 * 40 * The NVS region need not be page-aligned (both ends) and we arrange 41 * things so that the data from page-aligned addresses in this region will 42 * be copied into separate RAM pages. 43 */ 44 int suspend_nvs_register(unsigned long start, unsigned long size) 45 { 46 struct nvs_page *entry, *next; 47 48 pr_info("PM: Registering ACPI NVS region at %lx (%ld bytes)\n", 49 start, size); 50 51 while (size > 0) { 52 unsigned int nr_bytes; 53 54 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL); 55 if (!entry) 56 goto Error; 57 58 list_add_tail(&entry->node, &nvs_list); 59 entry->phys_start = start; 60 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK); 61 entry->size = (size < nr_bytes) ? size : nr_bytes; 62 63 start += entry->size; 64 size -= entry->size; 65 } 66 return 0; 67 68 Error: 69 list_for_each_entry_safe(entry, next, &nvs_list, node) { 70 list_del(&entry->node); 71 kfree(entry); 72 } 73 return -ENOMEM; 74 } 75 76 /** 77 * suspend_nvs_free - free data pages allocated for saving NVS regions 78 */ 79 void suspend_nvs_free(void) 80 { 81 struct nvs_page *entry; 82 83 list_for_each_entry(entry, &nvs_list, node) 84 if (entry->data) { 85 free_page((unsigned long)entry->data); 86 entry->data = NULL; 87 if (entry->kaddr) { 88 if (entry->unmap) { 89 iounmap(entry->kaddr); 90 entry->unmap = false; 91 } else { 92 acpi_os_unmap_memory(entry->kaddr, 93 entry->size); 94 } 95 entry->kaddr = NULL; 96 } 97 } 98 } 99 100 /** 101 * suspend_nvs_alloc - allocate memory necessary for saving NVS regions 102 */ 103 int suspend_nvs_alloc(void) 104 { 105 struct nvs_page *entry; 106 107 list_for_each_entry(entry, &nvs_list, node) { 108 entry->data = (void *)__get_free_page(GFP_KERNEL); 109 if (!entry->data) { 110 suspend_nvs_free(); 111 return -ENOMEM; 112 } 113 } 114 return 0; 115 } 116 117 /** 118 * suspend_nvs_save - save NVS memory regions 119 */ 120 int suspend_nvs_save(void) 121 { 122 struct nvs_page *entry; 123 124 printk(KERN_INFO "PM: Saving platform NVS memory\n"); 125 126 list_for_each_entry(entry, &nvs_list, node) 127 if (entry->data) { 128 unsigned long phys = entry->phys_start; 129 unsigned int size = entry->size; 130 131 entry->kaddr = acpi_os_get_iomem(phys, size); 132 if (!entry->kaddr) { 133 entry->kaddr = acpi_os_ioremap(phys, size); 134 entry->unmap = !!entry->kaddr; 135 } 136 if (!entry->kaddr) { 137 suspend_nvs_free(); 138 return -ENOMEM; 139 } 140 memcpy(entry->data, entry->kaddr, entry->size); 141 } 142 143 return 0; 144 } 145 146 /** 147 * suspend_nvs_restore - restore NVS memory regions 148 * 149 * This function is going to be called with interrupts disabled, so it 150 * cannot iounmap the virtual addresses used to access the NVS region. 151 */ 152 void suspend_nvs_restore(void) 153 { 154 struct nvs_page *entry; 155 156 printk(KERN_INFO "PM: Restoring platform NVS memory\n"); 157 158 list_for_each_entry(entry, &nvs_list, node) 159 if (entry->data) 160 memcpy(entry->kaddr, entry->data, entry->size); 161 } 162