bfin-otp.c revision 6038f373a3dc1f1c26496e60b6c40b164716f07e
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 32static 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 */ 39static 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 81static 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 */ 88static 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 */ 107static 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 */ 120static 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 174static 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 220static 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 228static 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 */ 240static 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 */ 263static void __exit bfin_otp_exit(void) 264{ 265 stampit(); 266 267 misc_deregister(&bfin_otp_misc_device); 268} 269 270module_init(bfin_otp_init); 271module_exit(bfin_otp_exit); 272 273MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); 274MODULE_DESCRIPTION("Blackfin OTP Memory Interface"); 275MODULE_LICENSE("GPL"); 276