drivers/char/bfin-otp.c

   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 <linux/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  */
  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  */
  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  */
 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  */
 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
 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 module_misc_device(bfin_otp_misc_device);
 234
 235 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
 236 MODULE_DESCRIPTION("Blackfin OTP Memory Interface");
 237 MODULE_LICENSE("GPL");