1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * OPAL PNOR flash MTD abstraction
4 *
5 * Copyright IBM 2015
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/errno.h>
11 #include <linux/of.h>
12 #include <linux/of_address.h>
13 #include <linux/platform_device.h>
14 #include <linux/string.h>
15 #include <linux/slab.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/mtd/partitions.h>
18
19 #include <linux/debugfs.h>
20 #include <linux/seq_file.h>
21
22 #include <asm/opal.h>
23
24
25 /*
26 * This driver creates the a Linux MTD abstraction for platform PNOR flash
27 * backed by OPAL calls
28 */
29
30 struct powernv_flash {
31 struct mtd_info mtd;
32 u32 id;
33 };
34
35 enum flash_op {
36 FLASH_OP_READ,
37 FLASH_OP_WRITE,
38 FLASH_OP_ERASE,
39 };
40
41 /*
42 * Don't return -ERESTARTSYS if we can't get a token, the MTD core
43 * might have split up the call from userspace and called into the
44 * driver more than once, we'll already have done some amount of work.
45 */
powernv_flash_async_op(struct mtd_info * mtd,enum flash_op op,loff_t offset,size_t len,size_t * retlen,u_char * buf)46 static int powernv_flash_async_op(struct mtd_info *mtd, enum flash_op op,
47 loff_t offset, size_t len, size_t *retlen, u_char *buf)
48 {
49 struct powernv_flash *info = (struct powernv_flash *)mtd->priv;
50 struct device *dev = &mtd->dev;
51 int token;
52 struct opal_msg msg;
53 int rc;
54
55 dev_dbg(dev, "%s(op=%d, offset=0x%llx, len=%zu)\n",
56 __func__, op, offset, len);
57
58 token = opal_async_get_token_interruptible();
59 if (token < 0) {
60 if (token != -ERESTARTSYS)
61 dev_err(dev, "Failed to get an async token\n");
62 else
63 token = -EINTR;
64 return token;
65 }
66
67 switch (op) {
68 case FLASH_OP_READ:
69 rc = opal_flash_read(info->id, offset, __pa(buf), len, token);
70 break;
71 case FLASH_OP_WRITE:
72 rc = opal_flash_write(info->id, offset, __pa(buf), len, token);
73 break;
74 case FLASH_OP_ERASE:
75 rc = opal_flash_erase(info->id, offset, len, token);
76 break;
77 default:
78 WARN_ON_ONCE(1);
79 opal_async_release_token(token);
80 return -EIO;
81 }
82
83 if (rc == OPAL_ASYNC_COMPLETION) {
84 rc = opal_async_wait_response_interruptible(token, &msg);
85 if (rc) {
86 /*
87 * If we return the mtd core will free the
88 * buffer we've just passed to OPAL but OPAL
89 * will continue to read or write from that
90 * memory.
91 * It may be tempting to ultimately return 0
92 * if we're doing a read or a write since we
93 * are going to end up waiting until OPAL is
94 * done. However, because the MTD core sends
95 * us the userspace request in chunks, we need
96 * it to know we've been interrupted.
97 */
98 rc = -EINTR;
99 if (opal_async_wait_response(token, &msg))
100 dev_err(dev, "opal_async_wait_response() failed\n");
101 goto out;
102 }
103 rc = opal_get_async_rc(msg);
104 }
105
106 /*
107 * OPAL does mutual exclusion on the flash, it will return
108 * OPAL_BUSY.
109 * During firmware updates by the service processor OPAL may
110 * be (temporarily) prevented from accessing the flash, in
111 * this case OPAL will also return OPAL_BUSY.
112 * Both cases aren't errors exactly but the flash could have
113 * changed, userspace should be informed.
114 */
115 if (rc != OPAL_SUCCESS && rc != OPAL_BUSY)
116 dev_err(dev, "opal_flash_async_op(op=%d) failed (rc %d)\n",
117 op, rc);
118
119 if (rc == OPAL_SUCCESS && retlen)
120 *retlen = len;
121
122 rc = opal_error_code(rc);
123 out:
124 opal_async_release_token(token);
125 return rc;
126 }
127
128 /**
129 * powernv_flash_read
130 * @mtd: the device
131 * @from: the offset to read from
132 * @len: the number of bytes to read
133 * @retlen: the number of bytes actually read
134 * @buf: the filled in buffer
135 *
136 * Returns 0 if read successful, or -ERRNO if an error occurred
137 */
powernv_flash_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)138 static int powernv_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
139 size_t *retlen, u_char *buf)
140 {
141 return powernv_flash_async_op(mtd, FLASH_OP_READ, from,
142 len, retlen, buf);
143 }
144
145 /**
146 * powernv_flash_write
147 * @mtd: the device
148 * @to: the offset to write to
149 * @len: the number of bytes to write
150 * @retlen: the number of bytes actually written
151 * @buf: the buffer to get bytes from
152 *
153 * Returns 0 if write successful, -ERRNO if error occurred
154 */
powernv_flash_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)155 static int powernv_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
156 size_t *retlen, const u_char *buf)
157 {
158 return powernv_flash_async_op(mtd, FLASH_OP_WRITE, to,
159 len, retlen, (u_char *)buf);
160 }
161
162 /**
163 * powernv_flash_erase
164 * @mtd: the device
165 * @erase: the erase info
166 * Returns 0 if erase successful or -ERRNO if an error occurred
167 */
powernv_flash_erase(struct mtd_info * mtd,struct erase_info * erase)168 static int powernv_flash_erase(struct mtd_info *mtd, struct erase_info *erase)
169 {
170 int rc;
171
172 rc = powernv_flash_async_op(mtd, FLASH_OP_ERASE, erase->addr,
173 erase->len, NULL, NULL);
174 if (rc)
175 erase->fail_addr = erase->addr;
176
177 return rc;
178 }
179
180 /**
181 * powernv_flash_set_driver_info - Fill the mtd_info structure and docg3
182 * @dev: The device structure
183 * @mtd: The structure to fill
184 */
powernv_flash_set_driver_info(struct device * dev,struct mtd_info * mtd)185 static int powernv_flash_set_driver_info(struct device *dev,
186 struct mtd_info *mtd)
187 {
188 u64 size;
189 u32 erase_size;
190 int rc;
191
192 rc = of_property_read_u32(dev->of_node, "ibm,flash-block-size",
193 &erase_size);
194 if (rc) {
195 dev_err(dev, "couldn't get resource block size information\n");
196 return rc;
197 }
198
199 rc = of_property_read_u64(dev->of_node, "reg", &size);
200 if (rc) {
201 dev_err(dev, "couldn't get resource size information\n");
202 return rc;
203 }
204
205 /*
206 * Going to have to check what details I need to set and how to
207 * get them
208 */
209 mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
210 if (!mtd->name)
211 return -ENOMEM;
212
213 mtd->type = MTD_NORFLASH;
214 mtd->flags = MTD_WRITEABLE;
215 mtd->size = size;
216 mtd->erasesize = erase_size;
217 mtd->writebufsize = mtd->writesize = 1;
218 mtd->owner = THIS_MODULE;
219 mtd->_erase = powernv_flash_erase;
220 mtd->_read = powernv_flash_read;
221 mtd->_write = powernv_flash_write;
222 mtd->dev.parent = dev;
223 mtd_set_of_node(mtd, dev->of_node);
224 return 0;
225 }
226
227 /**
228 * powernv_flash_probe
229 * @pdev: platform device
230 *
231 * Returns 0 on success, -ENOMEM, -ENXIO on error
232 */
powernv_flash_probe(struct platform_device * pdev)233 static int powernv_flash_probe(struct platform_device *pdev)
234 {
235 struct device *dev = &pdev->dev;
236 struct powernv_flash *data;
237 int ret;
238
239 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
240 if (!data)
241 return -ENOMEM;
242
243 data->mtd.priv = data;
244
245 ret = of_property_read_u32(dev->of_node, "ibm,opal-id", &(data->id));
246 if (ret) {
247 dev_err(dev, "no device property 'ibm,opal-id'\n");
248 return ret;
249 }
250
251 ret = powernv_flash_set_driver_info(dev, &data->mtd);
252 if (ret)
253 return ret;
254
255 dev_set_drvdata(dev, data);
256
257 /*
258 * The current flash that skiboot exposes is one contiguous flash chip
259 * with an ffs partition at the start, it should prove easier for users
260 * to deal with partitions or not as they see fit
261 */
262 return mtd_device_register(&data->mtd, NULL, 0);
263 }
264
265 /**
266 * op_release - Release the driver
267 * @pdev: the platform device
268 *
269 * Returns 0
270 */
powernv_flash_release(struct platform_device * pdev)271 static void powernv_flash_release(struct platform_device *pdev)
272 {
273 struct powernv_flash *data = dev_get_drvdata(&(pdev->dev));
274
275 /* All resources should be freed automatically */
276 WARN_ON(mtd_device_unregister(&data->mtd));
277 }
278
279 static const struct of_device_id powernv_flash_match[] = {
280 { .compatible = "ibm,opal-flash" },
281 {}
282 };
283
284 static struct platform_driver powernv_flash_driver = {
285 .driver = {
286 .name = "powernv_flash",
287 .of_match_table = powernv_flash_match,
288 },
289 .remove = powernv_flash_release,
290 .probe = powernv_flash_probe,
291 };
292
293 module_platform_driver(powernv_flash_driver);
294
295 MODULE_DEVICE_TABLE(of, powernv_flash_match);
296 MODULE_LICENSE("GPL");
297 MODULE_AUTHOR("Cyril Bur <cyril.bur@au1.ibm.com>");
298 MODULE_DESCRIPTION("MTD abstraction for OPAL flash");
299