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path: root/drivers/char/scx200_gpio.c
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2010-10-15llseek: automatically add .llseek fopArnd Bergmann
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>
2009-10-14drivers: Remove BKL from scx200_gpioThomas Gleixner
cycle_kernel_lock() was added during the big BKL pushdown. It should ensure the serializiation against driver init code. In this case there is nothing to serialize. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <20091010153350.167321547@linutronix.de> Acked-by: Jim Cromie <jim.cromie@gmail.com>
2008-06-20Add a bunch of cycle_kernel_lock() callsJonathan Corbet
All of the open() functions which don't need the BKL on their face may still depend on its acquisition to serialize opens against driver initialization. So make those functions acquire then release the BKL to be on the safe side. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2008-06-20Add "no BKL needed" comments to several driversJonathan Corbet
This documents the fact that somebody looked at the relevant open() functions and concluded that, due to their trivial nature, no locking was needed. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2006-09-29[PATCH] scx200_gpio export cleanupsChris Boot
Use EXPORT_SYMBOL_GPL for new symbols, and declare the struct in the header file for access by other modules. Signed-off-by: Chris Boot <bootc@bootc.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29[PATCH] drivers/char/scx200_gpio.c: make code staticJim Cromie
This patch makes a needlessly global variable static. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14[PATCH] gpio: rename exported vtables to better match purposeJim Cromie
- rename EXPORTed gpio vtables from {scx200,pc8736x}_access to _gpio_ops new name is much closer to the vtable-name struct nsc_gpio_ops, should be clearer. Also rename the _fops vtable var to _fileops to better disambiguate it from the gpio vtable. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14[PATCH] gpio: drop vtable members .gpio_set_high .gpio_set_low gpio_set is ↵Jim Cromie
enough drops gpio_set_high, gpio_set_low from the nsc_gpio_ops vtable. While we can't drop them from scx200_gpio (or can we?), we dont need them for new users of the exported vtable; gpio_set(1), gpio_set(0) work fine. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14[PATCH] scx200_gpio: use 1 cdev for N minors, not N for NJim Cromie
Remove the scx200_gpio's cdev-array & ksalloc, replacing it with a single static struct cdev, which is sufficient for all the pins. cdev_put is commented out since kernel wont link properly with it, and its apparently not needed. With these patches, this driver continues to work with Chris Boot's leds_48xx driver. Signed-off-by Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14[PATCH] scx200_gpio: 1 cdev for N minors: cleanup, prepJim Cromie
this patch is mostly cleanup of scx200_gpio : - drop #include <linux/config.h> - s/DEVNAME/DRVNAME/ apparently a convention - replace variable num_pins with #define MAX_PINS - s/dev/devid/ to clarify that its a dev_t, not a struct device dev. - move devid = MKDEV(major,0) into branch where its needed. 2 minor 'changes' : - reduced MAX_PINS from 64 to 32. Ive never tested other pins, and theyre all multiplexed with other functions, some of which may be in use on my soekris 4801, so I dont know what testing should yield. - +EXPORT_SYMBOL(scx200_access); This exposes the driver's vtable, which another driver can use along with #include <linux/nsc_gpio.h>, to manipulate a gpio-pin. Signed-off-by Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03[PATCH] make more file_operation structs staticArjan van de Ven
Mark the static struct file_operations in drivers/char as const. Making them const prevents accidental bugs, and moves them to the .rodata section so that they no longer do any false sharing; in addition with the proper debug option they are then protected against corruption.. [akpm@osdl.org: build fix] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] fix platform_device_put/del mishapsIngo Molnar
This fixes drivers/char/pc8736x_gpio.c and drivers/char/scx200_gpio.c to use the platform_device_del/put ops correctly. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Jim Cromie <jim.cromie@gmail.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: use dev_dbg in common moduleJim Cromie
Use of dev_dbg() and friends is considered good practice. dev_dbg() needs a struct device *devp, but nsc_gpio is only a helper module, so it doesnt have/need its own. To provide devp to the user-modules (scx200 & pc8736x _gpio), we add it to the vtable, and set it during init. Also squeeze nsc_gpio_dump()'s format a little. [ 199.259879] pc8736x_gpio.0: io09: 0x0044 TS OD PUE EDGE LO DEBOUNCE Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: migrate gpio_dump to common moduleJim Cromie
Since the meaning of config-bits is the same for scx200 and pc8736x _gpios, we can share a function to deliver this to user. Since it is called via the vtable, its also completely replaceable. For now, we keep using printk... Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: migrate file-ops to common moduleJim Cromie
Now that the read(), write() file-ops are dispatching gpio-ops via the vtable, they are generic, and can be moved 'verbatim' to the nsc_gpio common-support module. After the move, various symbols are renamed to update 'scx200_' to 'nsc_', and headers are adjusted accordingly. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: dispatch via vtableJim Cromie
Now actually call the gpio operations thru the vtable. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: add gpio-ops vtableJim Cromie
Abstract the gpio operations into a new nsc_gpio_ops vtable. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: add 'v' command to device-fileJim Cromie
Add a new driver command: 'v' which calls gpio_dump() on the pin. The output goes to the log, like all other INFO messages in the original driver. Giving the user control over the feedback they 'need' is construed to be a user-friendly feature, and allows us (later) to dial down many INFO messages to DEBUG log-level. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: add platforn_device for use w ↵Jim Cromie
dev_dbg Add a platform-device to scx200_gpio, and use its struct device dev member (ie: devp) in dev_dbg() once. There are 2 alternatives here (Im soliciting guidance/commentary): - use isa_device, if/when its added to the kernel. - alter scx200.c to EXPORT_GPL its private devp so that both scx200_gpio, and the (to be added) nsc_gpio module can use it. Since the available devp is in 'grandparent', this seems like too much 'action at a distance'. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: modernize driver init to 2.6 apiJim Cromie
Adopt many modern 2.6 coding practices, ala LDD3, chapter 3. Changes are limited to initialization calls from module init, ie: cdev_init, cdev_add, *_chrdev_region, mkdev. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27[PATCH] chardev: GPIO for SCx200 & PC-8736x: whitespace pre-cleanJim Cromie
GPIO SUPPORT FOR SCx200 & PC8736x The patch-set reworks the 2.4 vintage scx200_gpio driver for modern 2.6, and refactors GPIO support to reuse it in a new driver for the GPIO on PC-8736x chips. Its handy for the Soekris.com net-4801, which has both chips. These patches have been seen recently on Kernel-Mentors, and then Kernel-Newbies ML, where Jesper Juhl kindly reviewed it. His feedback has been incorporated. Thanks Jesper ! Its also gone to soekris-tech@soekris.com for possible testing by linux folks, I've gotten 1 promise so far. Theyre mostly BSD folk over there, but we'll see.. Device-file & Sysfs The driver preserves the existing device-file interface, including the write/cmd set, but adds v to 'view' the pin-settings & configs by inducing, via gpio_dump(), a dev_info() call. Its a fairly crappy way to get status, but it sticks to the syslog approach, conservatively. Allowing users to voluntarily trigger logging is good, it gives them a familiar way to confirm their app's control & use of the pins, and I've thus reduced the pin-mode-updates from dev_info to dev_dbg. I've recently bolted on a proto sysfs interface for both new drivers. Im not including those patches here; they (the patch + doc-pre-patch) are still quite raw (and unreviewed on KNML), and since they 'invent' a convention for GPIO, a proper vetting is needed. Since this patchset is much bigger than my previous ones, Id like to keep things simpler, and address it 1st, before bolting on more stuff. The driver-split The Geode CPU and the PC-87366 Super-IO chip have GPIO units which share a common pin-architecture (same pin features, with same bits controlling), but with different addressing mechanics and port organizations. The vintage driver expresses the pin capabilities with pin-mode commands [OoPpTt],etc that change the pin configurations, and since the 2 chips share pin-arch, we can reuse the read(), write() commands, once the implementation is suitably adjusted. The patchset adds a vtable: struct nsc_gpio_ops, to abstract the existing gpio operations, then adjusts fileops.write() code to invoke operations via that vtable. Driver specific open()s set private_data to the vtable so its available for use by write(). The vtable gets the gpio_dump() too, since its user-friendly, and (could be construed as) part of the current device-file interface. To support use of dev_dbg() in write() & _dump(), the vtable gets a dev ptr too, set by both scx200 & pc8736x _gpio drivers. heres how the pins are presented in syslog: [ 1890.176223] scx200_gpio.0: io00: 0x0044 TS OD PUE EDGE LO DEBOUNCE [ 1890.287223] scx200_gpio.0: io01: 0x0003 OE PP PUD EDGE LO nsc_gpio.c: new file is new home of several file-ops methods, which are modified to get their vtable from filp->private_data, and use it where needed. scx200_gpio.c: keeps some of its existing gpio routines, but now wires them up via the vtable (they're invoked by nsc_gpio.c:nsc_gpio_write() thru this vtable). A driver-spcific open() initializes filp->private_data with the vtable. Once the split is clean, and the scx200_gpio driver is working, we copy and modify the function and variable names, and rework the access-method bodies for the different addressing scheme. Heres a working overview of the patchset: # series file for GPIO # Spring Cleaning gpio-scx/patch.preclean # scripts/Lindent fixes, editor-ctrl comments # API Modernization gpio-scx/patch.api26 # what I learned from LDD3 gpio-scx/patch.platform-dev-2 # get pdev, support for dev_dbg() gpio-scx/patch.unsigned-minor # fix to match std practice # Debuggability gpio-scx/patch.dump-diet # shrink gpio_dump() gpio-scx/patch.viewpins # add new 'command' to call dump() gpio-scx/patch.init-refactor # pull shadow-register init to sub # Access-Abstraction (add vtable) gpio-scx/patch.access-vtable # introduce nsg_gpio_ops vtable, w dump gpio-scx/patch.vtable-calls # add & use the vtable in scx200_gpio gpio-scx/patch.nscgpio-shell # add empty driver for common-fops # move code under abstraction gpio-scx/patch.migrate-fops # move file-ops methods from scx200_gpio gpio-scx/patch.common-dump # mv scx200.c:scx200_gpio_dump() to nsc_gpio.c gpio-scx/patch.add-pc8736x-gpio # add new driver, like old, w chip adapt # gpio-scx/patch.add-DEBUG # enable all dev_dbg()s # Cleanups # finish printk -> dev_dbg() etc gpio-scx/patch.pdev-pc8736x # new drvr needs pdev too, gpio-scx/patch.devdbg-nscgpio # add device to 'vtable', use in dev_dbg() # gpio-scx/patch.pin-config-view # another 'c' 'command' # gpio-scx/quiet-getset # take out excess dbg stuff (pretty quiet now) gpio-scx/patch.shadow-current # imitate scx200_gpio's shadow regs in pc87* # post KMentors-post patches .. gpio-scx/patch.mutexes # use mutexes for config-locks gpio-scx/patch.viewpins-values # extend dump to obsolete separate 'c' cmd gpio-scx/patch.kconfig # add stuff for kbuild # TBC # combine api26 with pdev, which is just one step. # merge c&v commands to single do-all-fn # delay viewpins, dump-diet should also un-ifdef it too. diff.sys-gpio-rollup-1 This patch: Removed editor format-control comments, and used scripts/Lindent to clean up whitespace, then deleted the bogus chunks :-( Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!