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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Arnd Bergmann](/assets/img/avatar_default.png)
All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
275 lines
5.9 KiB
C
275 lines
5.9 KiB
C
/*
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* Blackfin On-Chip OTP Memory Interface
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*
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* Copyright 2007-2009 Analog Devices Inc.
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*
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* Enter bugs at http://blackfin.uclinux.org/
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <mtd/mtd-abi.h>
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#include <asm/blackfin.h>
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#include <asm/bfrom.h>
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#include <asm/uaccess.h>
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#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
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#define stampit() stamp("here i am")
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#define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
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#define DRIVER_NAME "bfin-otp"
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#define PFX DRIVER_NAME ": "
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static DEFINE_MUTEX(bfin_otp_lock);
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/**
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* bfin_otp_read - Read OTP pages
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*
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* All reads must be in half page chunks (half page == 64 bits).
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*/
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static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count, loff_t *pos)
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{
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ssize_t bytes_done;
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u32 page, flags, ret;
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u64 content;
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stampit();
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if (count % sizeof(u64))
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return -EMSGSIZE;
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if (mutex_lock_interruptible(&bfin_otp_lock))
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return -ERESTARTSYS;
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bytes_done = 0;
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page = *pos / (sizeof(u64) * 2);
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while (bytes_done < count) {
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flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
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stamp("processing page %i (0x%x:%s)", page, flags,
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(flags & OTP_UPPER_HALF ? "upper" : "lower"));
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ret = bfrom_OtpRead(page, flags, &content);
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if (ret & OTP_MASTER_ERROR) {
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stamp("error from otp: 0x%x", ret);
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bytes_done = -EIO;
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break;
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}
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if (copy_to_user(buff + bytes_done, &content, sizeof(content))) {
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bytes_done = -EFAULT;
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break;
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}
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if (flags & OTP_UPPER_HALF)
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++page;
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bytes_done += sizeof(content);
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*pos += sizeof(content);
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}
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mutex_unlock(&bfin_otp_lock);
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return bytes_done;
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}
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#ifdef CONFIG_BFIN_OTP_WRITE_ENABLE
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static bool allow_writes;
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/**
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* bfin_otp_init_timing - setup OTP timing parameters
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*
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* Required before doing any write operation. Algorithms from HRM.
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*/
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static u32 bfin_otp_init_timing(void)
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{
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u32 tp1, tp2, tp3, timing;
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tp1 = get_sclk() / 1000000;
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tp2 = (2 * get_sclk() / 10000000) << 8;
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tp3 = (0x1401) << 15;
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timing = tp1 | tp2 | tp3;
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if (bfrom_OtpCommand(OTP_INIT, timing))
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return 0;
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return timing;
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}
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/**
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* bfin_otp_deinit_timing - set timings to only allow reads
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*
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* Should be called after all writes are done.
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*/
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static void bfin_otp_deinit_timing(u32 timing)
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{
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/* mask bits [31:15] so that any attempts to write fail */
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bfrom_OtpCommand(OTP_CLOSE, 0);
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bfrom_OtpCommand(OTP_INIT, timing & ~(-1 << 15));
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bfrom_OtpCommand(OTP_CLOSE, 0);
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}
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/**
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* bfin_otp_write - write OTP pages
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*
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* All writes must be in half page chunks (half page == 64 bits).
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*/
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static ssize_t bfin_otp_write(struct file *filp, const char __user *buff, size_t count, loff_t *pos)
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{
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ssize_t bytes_done;
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u32 timing, page, base_flags, flags, ret;
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u64 content;
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if (!allow_writes)
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return -EACCES;
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if (count % sizeof(u64))
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return -EMSGSIZE;
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if (mutex_lock_interruptible(&bfin_otp_lock))
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return -ERESTARTSYS;
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stampit();
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timing = bfin_otp_init_timing();
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if (timing == 0) {
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mutex_unlock(&bfin_otp_lock);
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return -EIO;
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}
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base_flags = OTP_CHECK_FOR_PREV_WRITE;
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bytes_done = 0;
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page = *pos / (sizeof(u64) * 2);
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while (bytes_done < count) {
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flags = base_flags | (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
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stamp("processing page %i (0x%x:%s) from %p", page, flags,
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(flags & OTP_UPPER_HALF ? "upper" : "lower"), buff + bytes_done);
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if (copy_from_user(&content, buff + bytes_done, sizeof(content))) {
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bytes_done = -EFAULT;
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break;
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}
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ret = bfrom_OtpWrite(page, flags, &content);
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if (ret & OTP_MASTER_ERROR) {
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stamp("error from otp: 0x%x", ret);
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bytes_done = -EIO;
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break;
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}
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if (flags & OTP_UPPER_HALF)
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++page;
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bytes_done += sizeof(content);
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*pos += sizeof(content);
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}
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bfin_otp_deinit_timing(timing);
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mutex_unlock(&bfin_otp_lock);
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return bytes_done;
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}
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static long bfin_otp_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
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{
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stampit();
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switch (cmd) {
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case OTPLOCK: {
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u32 timing;
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int ret = -EIO;
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if (!allow_writes)
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return -EACCES;
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if (mutex_lock_interruptible(&bfin_otp_lock))
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return -ERESTARTSYS;
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timing = bfin_otp_init_timing();
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if (timing) {
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u32 otp_result = bfrom_OtpWrite(arg, OTP_LOCK, NULL);
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stamp("locking page %lu resulted in 0x%x", arg, otp_result);
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if (!(otp_result & OTP_MASTER_ERROR))
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ret = 0;
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bfin_otp_deinit_timing(timing);
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}
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mutex_unlock(&bfin_otp_lock);
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return ret;
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}
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case MEMLOCK:
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allow_writes = false;
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return 0;
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case MEMUNLOCK:
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allow_writes = true;
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return 0;
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}
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return -EINVAL;
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}
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#else
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# define bfin_otp_write NULL
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# define bfin_otp_ioctl NULL
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#endif
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static const struct file_operations bfin_otp_fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = bfin_otp_ioctl,
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.read = bfin_otp_read,
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.write = bfin_otp_write,
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.llseek = default_llseek,
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};
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static struct miscdevice bfin_otp_misc_device = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = DRIVER_NAME,
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.fops = &bfin_otp_fops,
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};
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/**
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* bfin_otp_init - Initialize module
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*
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* Registers the device and notifier handler. Actual device
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* initialization is handled by bfin_otp_open().
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*/
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static int __init bfin_otp_init(void)
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{
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int ret;
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stampit();
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ret = misc_register(&bfin_otp_misc_device);
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if (ret) {
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pr_init(KERN_ERR PFX "unable to register a misc device\n");
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return ret;
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}
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pr_init(KERN_INFO PFX "initialized\n");
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return 0;
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}
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/**
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* bfin_otp_exit - Deinitialize module
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*
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* Unregisters the device and notifier handler. Actual device
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* deinitialization is handled by bfin_otp_close().
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*/
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static void __exit bfin_otp_exit(void)
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{
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stampit();
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misc_deregister(&bfin_otp_misc_device);
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}
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module_init(bfin_otp_init);
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module_exit(bfin_otp_exit);
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MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
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MODULE_DESCRIPTION("Blackfin OTP Memory Interface");
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MODULE_LICENSE("GPL");
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