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  */
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  * @mtd: the device
130  * @from: the offset to read from
131  * @len: the number of bytes to read
132  * @retlen: the number of bytes actually read
133  * @buf: the filled in buffer
134  *
135  * Returns 0 if read successful, or -ERRNO if an error occurred
136  */
137 static int powernv_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
138 	     size_t *retlen, u_char *buf)
139 {
140 	return powernv_flash_async_op(mtd, FLASH_OP_READ, from,
141 			len, retlen, buf);
142 }
143 
144 /**
145  * @mtd: the device
146  * @to: the offset to write to
147  * @len: the number of bytes to write
148  * @retlen: the number of bytes actually written
149  * @buf: the buffer to get bytes from
150  *
151  * Returns 0 if write successful, -ERRNO if error occurred
152  */
153 static int powernv_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
154 		     size_t *retlen, const u_char *buf)
155 {
156 	return powernv_flash_async_op(mtd, FLASH_OP_WRITE, to,
157 			len, retlen, (u_char *)buf);
158 }
159 
160 /**
161  * @mtd: the device
162  * @erase: the erase info
163  * Returns 0 if erase successful or -ERRNO if an error occurred
164  */
165 static int powernv_flash_erase(struct mtd_info *mtd, struct erase_info *erase)
166 {
167 	int rc;
168 
169 	rc =  powernv_flash_async_op(mtd, FLASH_OP_ERASE, erase->addr,
170 			erase->len, NULL, NULL);
171 	if (rc)
172 		erase->fail_addr = erase->addr;
173 
174 	return rc;
175 }
176 
177 /**
178  * powernv_flash_set_driver_info - Fill the mtd_info structure and docg3
179  * structure @pdev: The platform device
180  * @mtd: The structure to fill
181  */
182 static int powernv_flash_set_driver_info(struct device *dev,
183 		struct mtd_info *mtd)
184 {
185 	u64 size;
186 	u32 erase_size;
187 	int rc;
188 
189 	rc = of_property_read_u32(dev->of_node, "ibm,flash-block-size",
190 			&erase_size);
191 	if (rc) {
192 		dev_err(dev, "couldn't get resource block size information\n");
193 		return rc;
194 	}
195 
196 	rc = of_property_read_u64(dev->of_node, "reg", &size);
197 	if (rc) {
198 		dev_err(dev, "couldn't get resource size information\n");
199 		return rc;
200 	}
201 
202 	/*
203 	 * Going to have to check what details I need to set and how to
204 	 * get them
205 	 */
206 	mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
207 	mtd->type = MTD_NORFLASH;
208 	mtd->flags = MTD_WRITEABLE;
209 	mtd->size = size;
210 	mtd->erasesize = erase_size;
211 	mtd->writebufsize = mtd->writesize = 1;
212 	mtd->owner = THIS_MODULE;
213 	mtd->_erase = powernv_flash_erase;
214 	mtd->_read = powernv_flash_read;
215 	mtd->_write = powernv_flash_write;
216 	mtd->dev.parent = dev;
217 	mtd_set_of_node(mtd, dev->of_node);
218 	return 0;
219 }
220 
221 /**
222  * powernv_flash_probe
223  * @pdev: platform device
224  *
225  * Returns 0 on success, -ENOMEM, -ENXIO on error
226  */
227 static int powernv_flash_probe(struct platform_device *pdev)
228 {
229 	struct device *dev = &pdev->dev;
230 	struct powernv_flash *data;
231 	int ret;
232 
233 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
234 	if (!data)
235 		return -ENOMEM;
236 
237 	data->mtd.priv = data;
238 
239 	ret = of_property_read_u32(dev->of_node, "ibm,opal-id", &(data->id));
240 	if (ret) {
241 		dev_err(dev, "no device property 'ibm,opal-id'\n");
242 		return ret;
243 	}
244 
245 	ret = powernv_flash_set_driver_info(dev, &data->mtd);
246 	if (ret)
247 		return ret;
248 
249 	dev_set_drvdata(dev, data);
250 
251 	/*
252 	 * The current flash that skiboot exposes is one contiguous flash chip
253 	 * with an ffs partition at the start, it should prove easier for users
254 	 * to deal with partitions or not as they see fit
255 	 */
256 	return mtd_device_register(&data->mtd, NULL, 0);
257 }
258 
259 /**
260  * op_release - Release the driver
261  * @pdev: the platform device
262  *
263  * Returns 0
264  */
265 static int powernv_flash_release(struct platform_device *pdev)
266 {
267 	struct powernv_flash *data = dev_get_drvdata(&(pdev->dev));
268 
269 	/* All resources should be freed automatically */
270 	return mtd_device_unregister(&(data->mtd));
271 }
272 
273 static const struct of_device_id powernv_flash_match[] = {
274 	{ .compatible = "ibm,opal-flash" },
275 	{}
276 };
277 
278 static struct platform_driver powernv_flash_driver = {
279 	.driver		= {
280 		.name		= "powernv_flash",
281 		.of_match_table	= powernv_flash_match,
282 	},
283 	.remove		= powernv_flash_release,
284 	.probe		= powernv_flash_probe,
285 };
286 
287 module_platform_driver(powernv_flash_driver);
288 
289 MODULE_DEVICE_TABLE(of, powernv_flash_match);
290 MODULE_LICENSE("GPL");
291 MODULE_AUTHOR("Cyril Bur <cyril.bur@au1.ibm.com>");
292 MODULE_DESCRIPTION("MTD abstraction for OPAL flash");
293