1 /*
2 * Blackfin On-Chip OTP Memory Interface
3 *
4 * Copyright 2007-2009 Analog Devices Inc.
5 *
6 * Enter bugs at http://blackfin.uclinux.org/
7 *
8 * Licensed under the GPL-2 or later.
9 */
10
11 #include <linux/device.h>
12 #include <linux/errno.h>
13 #include <linux/fs.h>
14 #include <linux/init.h>
15 #include <linux/miscdevice.h>
16 #include <linux/module.h>
17 #include <linux/mutex.h>
18 #include <linux/types.h>
19 #include <mtd/mtd-abi.h>
20
21 #include <asm/blackfin.h>
22 #include <asm/bfrom.h>
23 #include <asm/uaccess.h>
24
25 #define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
26 #define stampit() stamp("here i am")
27 #define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
28
29 #define DRIVER_NAME "bfin-otp"
30 #define PFX DRIVER_NAME ": "
31
32 static DEFINE_MUTEX(bfin_otp_lock);
33
34 /**
35 * bfin_otp_read - Read OTP pages
36 *
37 * All reads must be in half page chunks (half page == 64 bits).
38 */
bfin_otp_read(struct file * file,char __user * buff,size_t count,loff_t * pos)39 static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count, loff_t *pos)
40 {
41 ssize_t bytes_done;
42 u32 page, flags, ret;
43 u64 content;
44
45 stampit();
46
47 if (count % sizeof(u64))
48 return -EMSGSIZE;
49
50 if (mutex_lock_interruptible(&bfin_otp_lock))
51 return -ERESTARTSYS;
52
53 bytes_done = 0;
54 page = *pos / (sizeof(u64) * 2);
55 while (bytes_done < count) {
56 flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
57 stamp("processing page %i (0x%x:%s)", page, flags,
58 (flags & OTP_UPPER_HALF ? "upper" : "lower"));
59 ret = bfrom_OtpRead(page, flags, &content);
60 if (ret & OTP_MASTER_ERROR) {
61 stamp("error from otp: 0x%x", ret);
62 bytes_done = -EIO;
63 break;
64 }
65 if (copy_to_user(buff + bytes_done, &content, sizeof(content))) {
66 bytes_done = -EFAULT;
67 break;
68 }
69 if (flags & OTP_UPPER_HALF)
70 ++page;
71 bytes_done += sizeof(content);
72 *pos += sizeof(content);
73 }
74
75 mutex_unlock(&bfin_otp_lock);
76
77 return bytes_done;
78 }
79
80 #ifdef CONFIG_BFIN_OTP_WRITE_ENABLE
81 static bool allow_writes;
82
83 /**
84 * bfin_otp_init_timing - setup OTP timing parameters
85 *
86 * Required before doing any write operation. Algorithms from HRM.
87 */
bfin_otp_init_timing(void)88 static u32 bfin_otp_init_timing(void)
89 {
90 u32 tp1, tp2, tp3, timing;
91
92 tp1 = get_sclk() / 1000000;
93 tp2 = (2 * get_sclk() / 10000000) << 8;
94 tp3 = (0x1401) << 15;
95 timing = tp1 | tp2 | tp3;
96 if (bfrom_OtpCommand(OTP_INIT, timing))
97 return 0;
98
99 return timing;
100 }
101
102 /**
103 * bfin_otp_deinit_timing - set timings to only allow reads
104 *
105 * Should be called after all writes are done.
106 */
bfin_otp_deinit_timing(u32 timing)107 static void bfin_otp_deinit_timing(u32 timing)
108 {
109 /* mask bits [31:15] so that any attempts to write fail */
110 bfrom_OtpCommand(OTP_CLOSE, 0);
111 bfrom_OtpCommand(OTP_INIT, timing & ~(-1 << 15));
112 bfrom_OtpCommand(OTP_CLOSE, 0);
113 }
114
115 /**
116 * bfin_otp_write - write OTP pages
117 *
118 * All writes must be in half page chunks (half page == 64 bits).
119 */
bfin_otp_write(struct file * filp,const char __user * buff,size_t count,loff_t * pos)120 static ssize_t bfin_otp_write(struct file *filp, const char __user *buff, size_t count, loff_t *pos)
121 {
122 ssize_t bytes_done;
123 u32 timing, page, base_flags, flags, ret;
124 u64 content;
125
126 if (!allow_writes)
127 return -EACCES;
128
129 if (count % sizeof(u64))
130 return -EMSGSIZE;
131
132 if (mutex_lock_interruptible(&bfin_otp_lock))
133 return -ERESTARTSYS;
134
135 stampit();
136
137 timing = bfin_otp_init_timing();
138 if (timing == 0) {
139 mutex_unlock(&bfin_otp_lock);
140 return -EIO;
141 }
142
143 base_flags = OTP_CHECK_FOR_PREV_WRITE;
144
145 bytes_done = 0;
146 page = *pos / (sizeof(u64) * 2);
147 while (bytes_done < count) {
148 flags = base_flags | (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
149 stamp("processing page %i (0x%x:%s) from %p", page, flags,
150 (flags & OTP_UPPER_HALF ? "upper" : "lower"), buff + bytes_done);
151 if (copy_from_user(&content, buff + bytes_done, sizeof(content))) {
152 bytes_done = -EFAULT;
153 break;
154 }
155 ret = bfrom_OtpWrite(page, flags, &content);
156 if (ret & OTP_MASTER_ERROR) {
157 stamp("error from otp: 0x%x", ret);
158 bytes_done = -EIO;
159 break;
160 }
161 if (flags & OTP_UPPER_HALF)
162 ++page;
163 bytes_done += sizeof(content);
164 *pos += sizeof(content);
165 }
166
167 bfin_otp_deinit_timing(timing);
168
169 mutex_unlock(&bfin_otp_lock);
170
171 return bytes_done;
172 }
173
bfin_otp_ioctl(struct file * filp,unsigned cmd,unsigned long arg)174 static long bfin_otp_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
175 {
176 stampit();
177
178 switch (cmd) {
179 case OTPLOCK: {
180 u32 timing;
181 int ret = -EIO;
182
183 if (!allow_writes)
184 return -EACCES;
185
186 if (mutex_lock_interruptible(&bfin_otp_lock))
187 return -ERESTARTSYS;
188
189 timing = bfin_otp_init_timing();
190 if (timing) {
191 u32 otp_result = bfrom_OtpWrite(arg, OTP_LOCK, NULL);
192 stamp("locking page %lu resulted in 0x%x", arg, otp_result);
193 if (!(otp_result & OTP_MASTER_ERROR))
194 ret = 0;
195
196 bfin_otp_deinit_timing(timing);
197 }
198
199 mutex_unlock(&bfin_otp_lock);
200
201 return ret;
202 }
203
204 case MEMLOCK:
205 allow_writes = false;
206 return 0;
207
208 case MEMUNLOCK:
209 allow_writes = true;
210 return 0;
211 }
212
213 return -EINVAL;
214 }
215 #else
216 # define bfin_otp_write NULL
217 # define bfin_otp_ioctl NULL
218 #endif
219
220 static const struct file_operations bfin_otp_fops = {
221 .owner = THIS_MODULE,
222 .unlocked_ioctl = bfin_otp_ioctl,
223 .read = bfin_otp_read,
224 .write = bfin_otp_write,
225 .llseek = default_llseek,
226 };
227
228 static struct miscdevice bfin_otp_misc_device = {
229 .minor = MISC_DYNAMIC_MINOR,
230 .name = DRIVER_NAME,
231 .fops = &bfin_otp_fops,
232 };
233
234 /**
235 * bfin_otp_init - Initialize module
236 *
237 * Registers the device and notifier handler. Actual device
238 * initialization is handled by bfin_otp_open().
239 */
bfin_otp_init(void)240 static int __init bfin_otp_init(void)
241 {
242 int ret;
243
244 stampit();
245
246 ret = misc_register(&bfin_otp_misc_device);
247 if (ret) {
248 pr_init(KERN_ERR PFX "unable to register a misc device\n");
249 return ret;
250 }
251
252 pr_init(KERN_INFO PFX "initialized\n");
253
254 return 0;
255 }
256
257 /**
258 * bfin_otp_exit - Deinitialize module
259 *
260 * Unregisters the device and notifier handler. Actual device
261 * deinitialization is handled by bfin_otp_close().
262 */
bfin_otp_exit(void)263 static void __exit bfin_otp_exit(void)
264 {
265 stampit();
266
267 misc_deregister(&bfin_otp_misc_device);
268 }
269
270 module_init(bfin_otp_init);
271 module_exit(bfin_otp_exit);
272
273 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
274 MODULE_DESCRIPTION("Blackfin OTP Memory Interface");
275 MODULE_LICENSE("GPL");
276