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bfin-otp: add writing support
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The on-chip OTP may be written at runtime, so enable support for it in the
driver.  However, since writing should really be done only on development
systems, don't bend over backwards to make sure the simple software lock
is per-fd -- per-device is OK.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@vapier @torvalds
vapier authored and torvalds committed Sep 24, 2009
1 parent fbd8ae1 commit 156dd63
Showing 1 changed file with 129 additions and 44 deletions.
173 changes: 129 additions & 44 deletions drivers/char/bfin-otp.c
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Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
/*
* Blackfin On-Chip OTP Memory Interface
* Supports BF52x/BF54x
*
* Copyright 2007-2008 Analog Devices Inc.
* Copyright 2007-2009 Analog Devices Inc.
*
* Enter bugs at http://blackfin.uclinux.org/
*
Expand All @@ -17,8 +16,10 @@
#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)
Expand All @@ -30,39 +31,6 @@

static DEFINE_MUTEX(bfin_otp_lock);

/* OTP Boot ROM functions */
#define _BOOTROM_OTP_COMMAND 0xEF000018
#define _BOOTROM_OTP_READ 0xEF00001A
#define _BOOTROM_OTP_WRITE 0xEF00001C

static u32 (* const otp_command)(u32 command, u32 value) = (void *)_BOOTROM_OTP_COMMAND;
static u32 (* const otp_read)(u32 page, u32 flags, u64 *page_content) = (void *)_BOOTROM_OTP_READ;
static u32 (* const otp_write)(u32 page, u32 flags, u64 *page_content) = (void *)_BOOTROM_OTP_WRITE;

/* otp_command(): defines for "command" */
#define OTP_INIT 0x00000001
#define OTP_CLOSE 0x00000002

/* otp_{read,write}(): defines for "flags" */
#define OTP_LOWER_HALF 0x00000000 /* select upper/lower 64-bit half (bit 0) */
#define OTP_UPPER_HALF 0x00000001
#define OTP_NO_ECC 0x00000010 /* do not use ECC */
#define OTP_LOCK 0x00000020 /* sets page protection bit for page */
#define OTP_ACCESS_READ 0x00001000
#define OTP_ACCESS_READWRITE 0x00002000

/* Return values for all functions */
#define OTP_SUCCESS 0x00000000
#define OTP_MASTER_ERROR 0x001
#define OTP_WRITE_ERROR 0x003
#define OTP_READ_ERROR 0x005
#define OTP_ACC_VIO_ERROR 0x009
#define OTP_DATA_MULT_ERROR 0x011
#define OTP_ECC_MULT_ERROR 0x021
#define OTP_PREV_WR_ERROR 0x041
#define OTP_DATA_SB_WARN 0x100
#define OTP_ECC_SB_WARN 0x200

/**
* bfin_otp_read - Read OTP pages
*
Expand All @@ -86,17 +54,19 @@ static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count,
page = *pos / (sizeof(u64) * 2);
while (bytes_done < count) {
flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
stamp("processing page %i (%s)", page, (flags == OTP_UPPER_HALF ? "upper" : "lower"));
ret = otp_read(page, flags, &content);
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)
if (flags & OTP_UPPER_HALF)
++page;
bytes_done += sizeof(content);
*pos += sizeof(content);
Expand All @@ -108,35 +78,150 @@ static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count,
}

#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
* 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)
{
stampit();
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;

/* need otp_init() documentation before this can be implemented */
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 struct file_operations bfin_otp_fops = {
.owner = THIS_MODULE,
.read = bfin_otp_read,
.write = bfin_otp_write,
.owner = THIS_MODULE,
.unlocked_ioctl = bfin_otp_ioctl,
.read = bfin_otp_read,
.write = bfin_otp_write,
};

static struct miscdevice bfin_otp_misc_device = {
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