|
| 1 | +/* |
| 2 | + * Copyright(c) 2016 Intel Corporation. All rights reserved. |
| 3 | + * |
| 4 | + * This program is free software; you can redistribute it and/or modify |
| 5 | + * it under the terms of version 2 of the GNU General Public License as |
| 6 | + * published by the Free Software Foundation. |
| 7 | + * |
| 8 | + * This program is distributed in the hope that it will be useful, but |
| 9 | + * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 11 | + * General Public License for more details. |
| 12 | + */ |
| 13 | +#include <linux/pagemap.h> |
| 14 | +#include <linux/module.h> |
| 15 | +#include <linux/device.h> |
| 16 | +#include <linux/pfn_t.h> |
| 17 | +#include <linux/slab.h> |
| 18 | +#include <linux/dax.h> |
| 19 | +#include <linux/fs.h> |
| 20 | +#include <linux/mm.h> |
| 21 | + |
| 22 | +static int dax_major; |
| 23 | +static struct class *dax_class; |
| 24 | +static DEFINE_IDA(dax_minor_ida); |
| 25 | + |
| 26 | +/** |
| 27 | + * struct dax_region - mapping infrastructure for dax devices |
| 28 | + * @id: kernel-wide unique region for a memory range |
| 29 | + * @base: linear address corresponding to @res |
| 30 | + * @kref: to pin while other agents have a need to do lookups |
| 31 | + * @dev: parent device backing this region |
| 32 | + * @align: allocation and mapping alignment for child dax devices |
| 33 | + * @res: physical address range of the region |
| 34 | + * @pfn_flags: identify whether the pfns are paged back or not |
| 35 | + */ |
| 36 | +struct dax_region { |
| 37 | + int id; |
| 38 | + struct ida ida; |
| 39 | + void *base; |
| 40 | + struct kref kref; |
| 41 | + struct device *dev; |
| 42 | + unsigned int align; |
| 43 | + struct resource res; |
| 44 | + unsigned long pfn_flags; |
| 45 | +}; |
| 46 | + |
| 47 | +/** |
| 48 | + * struct dax_dev - subdivision of a dax region |
| 49 | + * @region - parent region |
| 50 | + * @dev - device backing the character device |
| 51 | + * @kref - enable this data to be tracked in filp->private_data |
| 52 | + * @id - child id in the region |
| 53 | + * @num_resources - number of physical address extents in this device |
| 54 | + * @res - array of physical address ranges |
| 55 | + */ |
| 56 | +struct dax_dev { |
| 57 | + struct dax_region *region; |
| 58 | + struct device *dev; |
| 59 | + struct kref kref; |
| 60 | + int id; |
| 61 | + int num_resources; |
| 62 | + struct resource res[0]; |
| 63 | +}; |
| 64 | + |
| 65 | +static void dax_region_free(struct kref *kref) |
| 66 | +{ |
| 67 | + struct dax_region *dax_region; |
| 68 | + |
| 69 | + dax_region = container_of(kref, struct dax_region, kref); |
| 70 | + kfree(dax_region); |
| 71 | +} |
| 72 | + |
| 73 | +void dax_region_put(struct dax_region *dax_region) |
| 74 | +{ |
| 75 | + kref_put(&dax_region->kref, dax_region_free); |
| 76 | +} |
| 77 | +EXPORT_SYMBOL_GPL(dax_region_put); |
| 78 | + |
| 79 | +static void dax_dev_free(struct kref *kref) |
| 80 | +{ |
| 81 | + struct dax_dev *dax_dev; |
| 82 | + |
| 83 | + dax_dev = container_of(kref, struct dax_dev, kref); |
| 84 | + dax_region_put(dax_dev->region); |
| 85 | + kfree(dax_dev); |
| 86 | +} |
| 87 | + |
| 88 | +static void dax_dev_put(struct dax_dev *dax_dev) |
| 89 | +{ |
| 90 | + kref_put(&dax_dev->kref, dax_dev_free); |
| 91 | +} |
| 92 | + |
| 93 | +struct dax_region *alloc_dax_region(struct device *parent, int region_id, |
| 94 | + struct resource *res, unsigned int align, void *addr, |
| 95 | + unsigned long pfn_flags) |
| 96 | +{ |
| 97 | + struct dax_region *dax_region; |
| 98 | + |
| 99 | + dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL); |
| 100 | + |
| 101 | + if (!dax_region) |
| 102 | + return NULL; |
| 103 | + |
| 104 | + memcpy(&dax_region->res, res, sizeof(*res)); |
| 105 | + dax_region->pfn_flags = pfn_flags; |
| 106 | + kref_init(&dax_region->kref); |
| 107 | + dax_region->id = region_id; |
| 108 | + ida_init(&dax_region->ida); |
| 109 | + dax_region->align = align; |
| 110 | + dax_region->dev = parent; |
| 111 | + dax_region->base = addr; |
| 112 | + |
| 113 | + return dax_region; |
| 114 | +} |
| 115 | +EXPORT_SYMBOL_GPL(alloc_dax_region); |
| 116 | + |
| 117 | +static ssize_t size_show(struct device *dev, |
| 118 | + struct device_attribute *attr, char *buf) |
| 119 | +{ |
| 120 | + struct dax_dev *dax_dev = dev_get_drvdata(dev); |
| 121 | + unsigned long long size = 0; |
| 122 | + int i; |
| 123 | + |
| 124 | + for (i = 0; i < dax_dev->num_resources; i++) |
| 125 | + size += resource_size(&dax_dev->res[i]); |
| 126 | + |
| 127 | + return sprintf(buf, "%llu\n", size); |
| 128 | +} |
| 129 | +static DEVICE_ATTR_RO(size); |
| 130 | + |
| 131 | +static struct attribute *dax_device_attributes[] = { |
| 132 | + &dev_attr_size.attr, |
| 133 | + NULL, |
| 134 | +}; |
| 135 | + |
| 136 | +static const struct attribute_group dax_device_attribute_group = { |
| 137 | + .attrs = dax_device_attributes, |
| 138 | +}; |
| 139 | + |
| 140 | +static const struct attribute_group *dax_attribute_groups[] = { |
| 141 | + &dax_device_attribute_group, |
| 142 | + NULL, |
| 143 | +}; |
| 144 | + |
| 145 | +static void unregister_dax_dev(void *_dev) |
| 146 | +{ |
| 147 | + struct device *dev = _dev; |
| 148 | + struct dax_dev *dax_dev = dev_get_drvdata(dev); |
| 149 | + struct dax_region *dax_region = dax_dev->region; |
| 150 | + |
| 151 | + dev_dbg(dev, "%s\n", __func__); |
| 152 | + |
| 153 | + get_device(dev); |
| 154 | + device_unregister(dev); |
| 155 | + ida_simple_remove(&dax_region->ida, dax_dev->id); |
| 156 | + ida_simple_remove(&dax_minor_ida, MINOR(dev->devt)); |
| 157 | + put_device(dev); |
| 158 | + dax_dev_put(dax_dev); |
| 159 | +} |
| 160 | + |
| 161 | +int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, |
| 162 | + int count) |
| 163 | +{ |
| 164 | + struct device *parent = dax_region->dev; |
| 165 | + struct dax_dev *dax_dev; |
| 166 | + struct device *dev; |
| 167 | + int rc, minor; |
| 168 | + dev_t dev_t; |
| 169 | + |
| 170 | + dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL); |
| 171 | + if (!dax_dev) |
| 172 | + return -ENOMEM; |
| 173 | + memcpy(dax_dev->res, res, sizeof(*res) * count); |
| 174 | + dax_dev->num_resources = count; |
| 175 | + kref_init(&dax_dev->kref); |
| 176 | + dax_dev->region = dax_region; |
| 177 | + kref_get(&dax_region->kref); |
| 178 | + |
| 179 | + dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL); |
| 180 | + if (dax_dev->id < 0) { |
| 181 | + rc = dax_dev->id; |
| 182 | + goto err_id; |
| 183 | + } |
| 184 | + |
| 185 | + minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL); |
| 186 | + if (minor < 0) { |
| 187 | + rc = minor; |
| 188 | + goto err_minor; |
| 189 | + } |
| 190 | + |
| 191 | + dev_t = MKDEV(dax_major, minor); |
| 192 | + dev = device_create_with_groups(dax_class, parent, dev_t, dax_dev, |
| 193 | + dax_attribute_groups, "dax%d.%d", dax_region->id, |
| 194 | + dax_dev->id); |
| 195 | + if (IS_ERR(dev)) { |
| 196 | + rc = PTR_ERR(dev); |
| 197 | + goto err_create; |
| 198 | + } |
| 199 | + dax_dev->dev = dev; |
| 200 | + |
| 201 | + rc = devm_add_action(dax_region->dev, unregister_dax_dev, dev); |
| 202 | + if (rc) { |
| 203 | + unregister_dax_dev(dev); |
| 204 | + return rc; |
| 205 | + } |
| 206 | + |
| 207 | + return 0; |
| 208 | + |
| 209 | + err_create: |
| 210 | + ida_simple_remove(&dax_minor_ida, minor); |
| 211 | + err_minor: |
| 212 | + ida_simple_remove(&dax_region->ida, dax_dev->id); |
| 213 | + err_id: |
| 214 | + dax_dev_put(dax_dev); |
| 215 | + |
| 216 | + return rc; |
| 217 | +} |
| 218 | +EXPORT_SYMBOL_GPL(devm_create_dax_dev); |
| 219 | + |
| 220 | +static const struct file_operations dax_fops = { |
| 221 | + .llseek = noop_llseek, |
| 222 | + .owner = THIS_MODULE, |
| 223 | +}; |
| 224 | + |
| 225 | +static int __init dax_init(void) |
| 226 | +{ |
| 227 | + int rc; |
| 228 | + |
| 229 | + rc = register_chrdev(0, "dax", &dax_fops); |
| 230 | + if (rc < 0) |
| 231 | + return rc; |
| 232 | + dax_major = rc; |
| 233 | + |
| 234 | + dax_class = class_create(THIS_MODULE, "dax"); |
| 235 | + if (IS_ERR(dax_class)) { |
| 236 | + unregister_chrdev(dax_major, "dax"); |
| 237 | + return PTR_ERR(dax_class); |
| 238 | + } |
| 239 | + |
| 240 | + return 0; |
| 241 | +} |
| 242 | + |
| 243 | +static void __exit dax_exit(void) |
| 244 | +{ |
| 245 | + class_destroy(dax_class); |
| 246 | + unregister_chrdev(dax_major, "dax"); |
| 247 | + ida_destroy(&dax_minor_ida); |
| 248 | +} |
| 249 | + |
| 250 | +MODULE_AUTHOR("Intel Corporation"); |
| 251 | +MODULE_LICENSE("GPL v2"); |
| 252 | +subsys_initcall(dax_init); |
| 253 | +module_exit(dax_exit); |
0 commit comments