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/*
* Blackfin On-Chip OTP Memory Interface
*
* Copyright 2007-2009 Analog Devices Inc.
*
* Enter bugs at http://blackfin.uclinux.org/
*
* Licensed under the GPL-2 or later.
*/
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <mtd/mtd-abi.h>
#include <asm/blackfin.h>
#include <asm/bfrom.h>
#include <asm/uaccess.h>
#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
#define stampit() stamp("here i am")
#define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
#define DRIVER_NAME "bfin-otp"
#define PFX DRIVER_NAME ": "
static DEFINE_MUTEX(bfin_otp_lock);
/**
* bfin_otp_read - Read OTP pages
*
* All reads must be in half page chunks (half page == 64 bits).
*/
static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count, loff_t *pos)
{
ssize_t bytes_done;
u32 page, flags, ret;
u64 content;
stampit();
if (count % sizeof(u64))
return -EMSGSIZE;
if (mutex_lock_interruptible(&bfin_otp_lock))
return -ERESTARTSYS;
bytes_done = 0;
page = *pos / (sizeof(u64) * 2);
while (bytes_done < count) {
flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
stamp("processing page %i (0x%x:%s)", page, flags,
(flags & OTP_UPPER_HALF ? "upper" : "lower"));
ret = bfrom_OtpRead(page, flags, &content);
if (ret & OTP_MASTER_ERROR) {
stamp("error from otp: 0x%x", ret);
bytes_done = -EIO;
break;
}
if (copy_to_user(buff + bytes_done, &content, sizeof(content))) {
bytes_done = -EFAULT;
break;
}
if (flags & OTP_UPPER_HALF)
++page;
bytes_done += sizeof(content);
*pos += sizeof(content);
}
mutex_unlock(&bfin_otp_lock);
return bytes_done;
}
#ifdef CONFIG_BFIN_OTP_WRITE_ENABLE
static bool allow_writes;
/**
* bfin_otp_init_timing - setup OTP timing parameters
*
* Required before doing any write operation. Algorithms from HRM.
*/
static u32 bfin_otp_init_timing(void)
{
u32 tp1, tp2, tp3, timing;
tp1 = get_sclk() / 1000000;
tp2 = (2 * get_sclk() / 10000000) << 8;
tp3 = (0x1401) << 15;
timing = tp1 | tp2 | tp3;
if (bfrom_OtpCommand(OTP_INIT, timing))
return 0;
return timing;
}
/**
* bfin_otp_deinit_timing - set timings to only allow reads
*
* Should be called after all writes are done.
*/
static void bfin_otp_deinit_timing(u32 timing)
{
/* mask bits [31:15] so that any attempts to write fail */
bfrom_OtpCommand(OTP_CLOSE, 0);
bfrom_OtpCommand(OTP_INIT, timing & ~(-1 << 15));
bfrom_OtpCommand(OTP_CLOSE, 0);
}
/**
* bfin_otp_write - write OTP pages
*
* All writes must be in half page chunks (half page == 64 bits).
*/
static ssize_t bfin_otp_write(struct file *filp, const char __user *buff, size_t count, loff_t *pos)
{
ssize_t bytes_done;
u32 timing, page, base_flags, flags, ret;
u64 content;
if (!allow_writes)
return -EACCES;
if (count % sizeof(u64))
return -EMSGSIZE;
if (mutex_lock_interruptible(&bfin_otp_lock))
return -ERESTARTSYS;
stampit();
timing = bfin_otp_init_timing();
if (timing == 0) {
mutex_unlock(&bfin_otp_lock);
return -EIO;
}
base_flags = OTP_CHECK_FOR_PREV_WRITE;
bytes_done = 0;
page = *pos / (sizeof(u64) * 2);
while (bytes_done < count) {
flags = base_flags | (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
stamp("processing page %i (0x%x:%s) from %p", page, flags,
(flags & OTP_UPPER_HALF ? "upper" : "lower"), buff + bytes_done);
if (copy_from_user(&content, buff + bytes_done, sizeof(content))) {
bytes_done = -EFAULT;
break;
}
ret = bfrom_OtpWrite(page, flags, &content);
if (ret & OTP_MASTER_ERROR) {
stamp("error from otp: 0x%x", ret);
bytes_done = -EIO;
break;
}
if (flags & OTP_UPPER_HALF)
++page;
bytes_done += sizeof(content);
*pos += sizeof(content);
}
bfin_otp_deinit_timing(timing);
mutex_unlock(&bfin_otp_lock);
return bytes_done;
}
static long bfin_otp_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
{
stampit();
switch (cmd) {
case OTPLOCK: {
u32 timing;
int ret = -EIO;
if (!allow_writes)
return -EACCES;
if (mutex_lock_interruptible(&bfin_otp_lock))
return -ERESTARTSYS;
timing = bfin_otp_init_timing();
if (timing) {
u32 otp_result = bfrom_OtpWrite(arg, OTP_LOCK, NULL);
stamp("locking page %lu resulted in 0x%x", arg, otp_result);
if (!(otp_result & OTP_MASTER_ERROR))
ret = 0;
bfin_otp_deinit_timing(timing);
}
mutex_unlock(&bfin_otp_lock);
return ret;
}
case MEMLOCK:
allow_writes = false;
return 0;
case MEMUNLOCK:
allow_writes = true;
return 0;
}
return -EINVAL;
}
#else
# define bfin_otp_write NULL
# define bfin_otp_ioctl NULL
#endif
static const struct file_operations bfin_otp_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = bfin_otp_ioctl,
.read = bfin_otp_read,
.write = bfin_otp_write,
.llseek = default_llseek,
};
static struct miscdevice bfin_otp_misc_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = DRIVER_NAME,
.fops = &bfin_otp_fops,
};
module_misc_device(bfin_otp_misc_device);
MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
MODULE_DESCRIPTION("Blackfin OTP Memory Interface");
MODULE_LICENSE("GPL");
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