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>
358 lines
7.5 KiB
C
358 lines
7.5 KiB
C
/*!***************************************************************************
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*!
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*! FILE NAME : ds1302.c
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*!
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*! DESCRIPTION: Implements an interface for the DS1302 RTC
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*!
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*! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init, get_rtc_status
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*!
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*! ---------------------------------------------------------------------------
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*!
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*! (C) Copyright 1999, 2000, 2001 Axis Communications AB, LUND, SWEDEN
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*!
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*!***************************************************************************/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/miscdevice.h>
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#include <linux/delay.h>
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#include <linux/bcd.h>
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#include <linux/smp_lock.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <asm/system.h>
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#include <asm/rtc.h>
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#if defined(CONFIG_M32R)
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#include <asm/m32r.h>
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#endif
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#define RTC_MAJOR_NR 121 /* local major, change later */
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static const char ds1302_name[] = "ds1302";
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/* Send 8 bits. */
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static void
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out_byte_rtc(unsigned int reg_addr, unsigned char x)
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{
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//RST H
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outw(0x0001,(unsigned long)PLD_RTCRSTODT);
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//write data
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outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
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//WE
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outw(0x0002,(unsigned long)PLD_RTCCR);
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//wait
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while(inw((unsigned long)PLD_RTCCR));
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//RST L
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outw(0x0000,(unsigned long)PLD_RTCRSTODT);
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}
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static unsigned char
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in_byte_rtc(unsigned int reg_addr)
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{
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unsigned char retval;
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//RST H
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outw(0x0001,(unsigned long)PLD_RTCRSTODT);
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//write data
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outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
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//RE
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outw(0x0001,(unsigned long)PLD_RTCCR);
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//wait
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while(inw((unsigned long)PLD_RTCCR));
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//read data
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retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;
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//RST L
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outw(0x0000,(unsigned long)PLD_RTCRSTODT);
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return retval;
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}
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/* Enable writing. */
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static void
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ds1302_wenable(void)
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{
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out_byte_rtc(0x8e,0x00);
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}
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/* Disable writing. */
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static void
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ds1302_wdisable(void)
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{
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out_byte_rtc(0x8e,0x80);
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}
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/* Read a byte from the selected register in the DS1302. */
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unsigned char
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ds1302_readreg(int reg)
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{
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unsigned char x;
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x=in_byte_rtc((0x81 | (reg << 1))); /* read register */
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return x;
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}
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/* Write a byte to the selected register. */
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void
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ds1302_writereg(int reg, unsigned char val)
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{
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ds1302_wenable();
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out_byte_rtc((0x80 | (reg << 1)),val);
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ds1302_wdisable();
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}
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void
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get_rtc_time(struct rtc_time *rtc_tm)
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{
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unsigned long flags;
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local_irq_save(flags);
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rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
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rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
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rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
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rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
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rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
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rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
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local_irq_restore(flags);
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rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
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rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
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rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
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rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
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rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
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rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
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/*
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* Account for differences between how the RTC uses the values
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* and how they are defined in a struct rtc_time;
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*/
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if (rtc_tm->tm_year <= 69)
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rtc_tm->tm_year += 100;
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rtc_tm->tm_mon--;
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}
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static unsigned char days_in_mo[] =
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{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
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/* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
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static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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unsigned long flags;
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switch(cmd) {
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case RTC_RD_TIME: /* read the time/date from RTC */
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{
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struct rtc_time rtc_tm;
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memset(&rtc_tm, 0, sizeof (struct rtc_time));
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lock_kernel();
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get_rtc_time(&rtc_tm);
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unlock_kernel();
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if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
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return -EFAULT;
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return 0;
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}
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case RTC_SET_TIME: /* set the RTC */
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{
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struct rtc_time rtc_tm;
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unsigned char mon, day, hrs, min, sec, leap_yr;
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unsigned int yrs;
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if (!capable(CAP_SYS_TIME))
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return -EPERM;
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if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
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return -EFAULT;
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yrs = rtc_tm.tm_year + 1900;
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mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
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day = rtc_tm.tm_mday;
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hrs = rtc_tm.tm_hour;
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min = rtc_tm.tm_min;
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sec = rtc_tm.tm_sec;
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if ((yrs < 1970) || (yrs > 2069))
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return -EINVAL;
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leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
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if ((mon > 12) || (day == 0))
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return -EINVAL;
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if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
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return -EINVAL;
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if ((hrs >= 24) || (min >= 60) || (sec >= 60))
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return -EINVAL;
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if (yrs >= 2000)
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yrs -= 2000; /* RTC (0, 1, ... 69) */
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else
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yrs -= 1900; /* RTC (70, 71, ... 99) */
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sec = bin2bcd(sec);
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min = bin2bcd(min);
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hrs = bin2bcd(hrs);
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day = bin2bcd(day);
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mon = bin2bcd(mon);
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yrs = bin2bcd(yrs);
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lock_kernel();
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local_irq_save(flags);
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CMOS_WRITE(yrs, RTC_YEAR);
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CMOS_WRITE(mon, RTC_MONTH);
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CMOS_WRITE(day, RTC_DAY_OF_MONTH);
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CMOS_WRITE(hrs, RTC_HOURS);
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CMOS_WRITE(min, RTC_MINUTES);
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CMOS_WRITE(sec, RTC_SECONDS);
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local_irq_restore(flags);
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unlock_kernel();
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/* Notice that at this point, the RTC is updated but
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* the kernel is still running with the old time.
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* You need to set that separately with settimeofday
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* or adjtimex.
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*/
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return 0;
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}
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case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
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{
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int tcs_val;
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if (!capable(CAP_SYS_TIME))
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return -EPERM;
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if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
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return -EFAULT;
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lock_kernel();
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tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
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ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
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unlock_kernel();
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return 0;
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}
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default:
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return -EINVAL;
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}
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}
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int
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get_rtc_status(char *buf)
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{
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char *p;
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struct rtc_time tm;
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p = buf;
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get_rtc_time(&tm);
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/*
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* There is no way to tell if the luser has the RTC set for local
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* time or for Universal Standard Time (GMT). Probably local though.
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*/
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p += sprintf(p,
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"rtc_time\t: %02d:%02d:%02d\n"
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"rtc_date\t: %04d-%02d-%02d\n",
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tm.tm_hour, tm.tm_min, tm.tm_sec,
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tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
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return p - buf;
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}
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/* The various file operations we support. */
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static const struct file_operations rtc_fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = rtc_ioctl,
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.llseek = noop_llseek,
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};
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/* Probe for the chip by writing something to its RAM and try reading it back. */
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#define MAGIC_PATTERN 0x42
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static int __init
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ds1302_probe(void)
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{
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int retval, res, baur;
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baur=(boot_cpu_data.bus_clock/(2*1000*1000));
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printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);
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outw(0x0000,(unsigned long)PLD_RTCCR);
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outw(0x0000,(unsigned long)PLD_RTCRSTODT);
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outw(baur,(unsigned long)PLD_RTCBAUR);
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/* Try to talk to timekeeper. */
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ds1302_wenable();
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/* write RAM byte 0 */
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/* write something magic */
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out_byte_rtc(0xc0,MAGIC_PATTERN);
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/* read RAM byte 0 */
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if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
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char buf[100];
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ds1302_wdisable();
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printk("%s: RTC found.\n", ds1302_name);
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get_rtc_status(buf);
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printk(buf);
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retval = 1;
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} else {
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printk("%s: RTC not found.\n", ds1302_name);
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retval = 0;
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}
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return retval;
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}
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/* Just probe for the RTC and register the device to handle the ioctl needed. */
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int __init
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ds1302_init(void)
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{
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if (!ds1302_probe()) {
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return -1;
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}
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return 0;
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}
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static int __init ds1302_register(void)
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{
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ds1302_init();
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if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
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printk(KERN_INFO "%s: unable to get major %d for rtc\n",
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ds1302_name, RTC_MAJOR_NR);
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return -1;
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}
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return 0;
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}
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module_init(ds1302_register);
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