From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758728AbXK0K6n (ORCPT ); Tue, 27 Nov 2007 05:58:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756105AbXK0K6f (ORCPT ); Tue, 27 Nov 2007 05:58:35 -0500 Received: from wa-out-1112.google.com ([209.85.146.176]:15489 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755732AbXK0K6e (ORCPT ); Tue, 27 Nov 2007 05:58:34 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=xvMVbNNGZfrGxClNO8GXa4nI8b6MlHDKzbAXS8N10zLuzRL+uFg9b3SKS6iMcmEuLG7HByJfdQfaAmrk6LWi7wEp+K6E4FoBB1+g3Ttobv1EOMyzHg8A39Jp7DeH93X7M07CMaVKCd5djLYrub683d+Ax7kLGF71aFEaJETA5Pc= Message-ID: Date: Tue, 27 Nov 2007 18:58:33 +0800 From: "eric miao" To: "David Brownell" Subject: Re: [patch/rfc 1/4] GPIO implementation framework Cc: "Linux Kernel list" , "Felipe Balbi" , "Bill Gatliff" , "Haavard Skinnemoen" , "Andrew Victor" , "Tony Lindgren" , "Jean Delvare" , "Kevin Hilman" , "Paul Mundt" , "Ben Dooks" In-Reply-To: <200711261746.55235.david-b@pacbell.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200710291809.29936.david-b@pacbell.net> <200711132308.48779.david-b@pacbell.net> <200711261746.55235.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org OK, here's the all-in-one patch based on David's most recent gpiolib fix, Changes include: 1. use per gpio structure "gpio_desc", thus eliminating the restriction of ARCH_GPIOS_PER_CHIP, thus making it possible leaving no holes in GPIOs numbering Note: the number of GPIOs on different GPIO expander chips may vary much, from 1-2 GPIOs on some audio codecs to dedicated 16-pin GPIO expander chips. The ARCH_GPIOS_PER_CHIP might not be fair enough. this change introduces the following small changes: a) removal of "gpio_chips[]" and use "gpio_desc[]" instead b) move of "is_out" and "requested" from "struct gpio_chip" to "struct gpio_desc" and make them bit fields c) removal of "gpiochip_is_requested()", and use "gpio_desc->requested" instead Note: I do want a reference count field within gpio_chip to record the number of requested GPIOs within the chip, leave this to next patch d) make gpio_ensure_requested() use gpio_desc, and simplify the code a bit 2. reduce ARCH_NR_GPIOS to 256, which is moderate for most sane platforms, and thus saving some memory of the per gpio structures 3. dedicated "gpio_desc.requested_label" field for use with debugfs 4. use a loop for "gpio_desc[]" instead of a loop for "gpio_chips[]" in gpiolib_show(), change is straight forward; since it is now per gpio based, the gpio_chip.dbg_show() is removed as well ------ >8 ------- diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 869b739..e3b2c8f 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -14,14 +14,20 @@ */ #ifndef ARCH_NR_GPIOS -#define ARCH_NR_GPIOS 512 -#endif - -#ifndef ARCH_GPIOS_PER_CHIP -#define ARCH_GPIOS_PER_CHIP BITS_PER_LONG +#define ARCH_NR_GPIOS 256 #endif struct seq_file; +struct gpio_chip; + +struct gpio_desc { + struct gpio_chip *chip; + unsigned is_out:1; + unsigned requested:1; +#ifdef CONFIG_DEBUG_FS + const char *requested_label; +#endif +}; /** * struct gpio_chip - abstract a GPIO controller @@ -41,8 +47,6 @@ struct seq_file; * (base + ngpio - 1). * @can_sleep: flag must be set iff get()/set() methods sleep, as they * must while accessing GPIO expander chips over I2C or SPI - * @is_out: bit array where bit N is true iff GPIO with offset N has been - * called successfully to configure this as an output * * A gpio_chip can help platforms abstract various sources of GPIOs so * they can all be accessed through a common programing interface. @@ -65,37 +69,11 @@ struct gpio_chip { unsigned offset, int value); void (*set)(struct gpio_chip *chip, unsigned offset, int value); - void (*dbg_show)(struct seq_file *s, - struct gpio_chip *chip); int base; u16 ngpio; unsigned can_sleep:1; - - /* other fields are modified by the gpio library only */ - DECLARE_BITMAP(is_out, ARCH_GPIOS_PER_CHIP); - -#ifdef CONFIG_DEBUG_FS - /* fat bits */ - const char *requested[ARCH_GPIOS_PER_CHIP]; -#else - /* thin bits */ - DECLARE_BITMAP(requested, ARCH_GPIOS_PER_CHIP); -#endif }; -/* returns true iff a given gpio signal has been requested; - * primarily for code dumping gpio_chip state. - */ -static inline int -gpiochip_is_requested(struct gpio_chip *chip, unsigned offset) -{ -#ifdef CONFIG_DEBUG_FS - return chip->requested[offset] != NULL; -#else - return test_bit(offset, chip->requested); -#endif -} - /* add/remove chips */ extern int gpiochip_add(struct gpio_chip *chip); extern int __must_check gpiochip_remove(struct gpio_chip *chip); diff --git a/lib/gpiolib.c b/lib/gpiolib.c index a853715..f24182e 100644 --- a/lib/gpiolib.c +++ b/lib/gpiolib.c @@ -28,39 +28,30 @@ #define extra_checks 0 #endif -/* gpio_lock protects the table of chips and gpio_chip->requested. +/* gpio_lock protects the table of gpio_desc[] and desc->requested. * While any GPIO is requested, its gpio_chip is not removable; * each GPIO's "requested" flag serves as a lock and refcount. */ static DEFINE_SPINLOCK(gpio_lock); -static struct gpio_chip *chips[DIV_ROUND_UP(ARCH_NR_GPIOS, - ARCH_GPIOS_PER_CHIP)]; - +struct gpio_desc gpio_desc[ARCH_NR_GPIOS]; /* Warn when drivers omit gpio_request() calls -- legal but * ill-advised when setting direction, and otherwise illegal. */ -static void gpio_ensure_requested(struct gpio_chip *chip, unsigned offset) +static void gpio_ensure_requested(struct gpio_desc *desc, unsigned gpio) { - int requested; - #ifdef CONFIG_DEBUG_FS - requested = (int) chip->requested[offset]; - if (!requested) - chip->requested[offset] = "[auto]"; -#else - requested = test_and_set_bit(offset, chip->requested); + if (!desc->requested) + desc->requested_label = "(auto)"; #endif - - if (!requested) - printk(KERN_DEBUG "GPIO-%d autorequested\n", - chip->base + offset); + if (!desc->requested) + printk(KERN_DEBUG "GPIO-%d autorequested\n", gpio); } /* caller holds gpio_lock *OR* gpio is marked as requested */ static inline struct gpio_chip *gpio_to_chip(unsigned gpio) { - return chips[gpio / ARCH_GPIOS_PER_CHIP]; + return gpio_desc[gpio].chip; } /** @@ -75,26 +66,25 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio) int gpiochip_add(struct gpio_chip *chip) { unsigned long flags; - int status = 0; unsigned id; - if (chip->base < 0 || (chip->base % ARCH_GPIOS_PER_CHIP) != 0) - return -EINVAL; - if ((chip->base + chip->ngpio) >= ARCH_NR_GPIOS) - return -EINVAL; - if (chip->ngpio > ARCH_GPIOS_PER_CHIP) + if (chip->base < 0 || (chip->base + chip->ngpio) >= ARCH_NR_GPIOS) return -EINVAL; spin_lock_irqsave(&gpio_lock, flags); - id = chip->base / ARCH_GPIOS_PER_CHIP; - if (chips[id] == NULL) - chips[id] = chip; - else - status = -EBUSY; + /* make sure the GPIOs are not claimed by any gpio_chip */ + for (id = chip->base; id < chip->base + chip->ngpio; id++) + if (gpio_desc[id].chip != NULL) { + spin_unlock_irqrestore(&gpio_lock, flags); + return -EBUSY; + } + + for (id = chip->base; id < chip->base + chip->ngpio; id++) + gpio_desc[id].chip = chip; spin_unlock_irqrestore(&gpio_lock, flags); - return status; + return 0; } EXPORT_SYMBOL_GPL(gpiochip_add); @@ -107,28 +97,21 @@ EXPORT_SYMBOL_GPL(gpiochip_add); int gpiochip_remove(struct gpio_chip *chip) { unsigned long flags; - int status = 0; - int offset; - unsigned id = chip->base / ARCH_GPIOS_PER_CHIP; + unsigned id; spin_lock_irqsave(&gpio_lock, flags); - for (offset = 0; offset < chip->ngpio; offset++) { - if (gpiochip_is_requested(chip, offset)) { - status = -EBUSY; - break; + for (id = chip->base; id < chip->base + chip->ngpio; id++) + if (gpio_desc[id].requested) { + spin_unlock_irqrestore(&gpio_lock, flags); + return -EBUSY; } - } - if (status == 0) { - if (chips[id] == chip) - chips[id] = NULL; - else - status = -EINVAL; - } + for (id = chip->base; id < chip->base + chip->ngpio; id++) + gpio_desc[id].chip = NULL; spin_unlock_irqrestore(&gpio_lock, flags); - return status; + return 0; } EXPORT_SYMBOL_GPL(gpiochip_remove); @@ -139,17 +122,15 @@ EXPORT_SYMBOL_GPL(gpiochip_remove); */ int gpio_request(unsigned gpio, const char *label) { - struct gpio_chip *chip; + struct gpio_desc *desc; int status = -EINVAL; unsigned long flags; spin_lock_irqsave(&gpio_lock, flags); - chip = gpio_to_chip(gpio); - if (!chip) - goto done; - gpio -= chip->base; - if (gpio >= chip->ngpio) + desc = &gpio_desc[gpio]; + + if (desc->chip == NULL) goto done; /* NOTE: gpio_request() can be called in early boot, @@ -157,18 +138,16 @@ int gpio_request(unsigned gpio, const char *label) */ status = 0; -#ifdef CONFIG_DEBUG_FS - if (!label) - label = "?"; - if (chip->requested[gpio]) - status = -EBUSY; + + if (!desc->requested) + desc->requested = 1; else - chip->requested[gpio] = label; -#else - if (test_and_set_bit(gpio, chip->requested)) status = -EBUSY; -#endif +#ifdef CONFIG_DEBUG_FS + if (status == 0) + desc->requested_label = (label == NULL) ? "?" : label; +#endif done: spin_unlock_irqrestore(&gpio_lock, flags); return status; @@ -178,27 +157,23 @@ EXPORT_SYMBOL_GPL(gpio_request); void gpio_free(unsigned gpio) { unsigned long flags; - struct gpio_chip *chip; + struct gpio_desc *desc; spin_lock_irqsave(&gpio_lock, flags); - chip = gpio_to_chip(gpio); - if (!chip) - goto done; - gpio -= chip->base; - if (gpio >= chip->ngpio) + desc = &gpio_desc[gpio]; + + if (desc->chip == NULL) goto done; -#ifdef CONFIG_DEBUG_FS - if (chip->requested[gpio]) - chip->requested[gpio] = NULL; + if (desc->requested) + desc->requested = 0; else - chip = NULL; -#else - if (!test_and_clear_bit(gpio, chip->requested)) - chip = NULL; + WARN_ON(extra_checks); + +#ifdef CONFIG_DEBUG_FS + desc->requested_label = NULL; #endif - WARN_ON(extra_checks && chip == NULL); done: spin_unlock_irqrestore(&gpio_lock, flags); } @@ -218,17 +193,22 @@ int gpio_direction_input(unsigned gpio) { unsigned long flags; struct gpio_chip *chip; + struct gpio_desc *desc; int status = -EINVAL; spin_lock_irqsave(&gpio_lock, flags); - chip = gpio_to_chip(gpio); + desc = &gpio_desc[gpio]; + chip = desc->chip; + + gpio_ensure_requested(desc, gpio); + if (!chip || !chip->get || !chip->direction_input) goto fail; + gpio -= chip->base; if (gpio >= chip->ngpio) goto fail; - gpio_ensure_requested(chip, gpio); /* now we know the gpio is valid and chip won't vanish */ @@ -237,8 +217,8 @@ int gpio_direction_input(unsigned gpio) might_sleep_if(extra_checks && chip->can_sleep); status = chip->direction_input(chip, gpio); - if (status == 0) - clear_bit(gpio, chip->is_out); + if (status) + desc->is_out = 0; return status; fail: spin_unlock_irqrestore(&gpio_lock, flags); @@ -250,17 +230,22 @@ int gpio_direction_output(unsigned gpio, int value) { unsigned long flags; struct gpio_chip *chip; + struct gpio_desc *desc; int status = -EINVAL; spin_lock_irqsave(&gpio_lock, flags); - chip = gpio_to_chip(gpio); + desc = &gpio_desc[gpio]; + chip = desc->chip; + + gpio_ensure_requested(desc, gpio); + if (!chip || !chip->set || !chip->direction_output) goto fail; + gpio -= chip->base; if (gpio >= chip->ngpio) goto fail; - gpio_ensure_requested(chip, gpio); /* now we know the gpio is valid and chip won't vanish */ @@ -269,8 +254,8 @@ int gpio_direction_output(unsigned gpio, int value) might_sleep_if(extra_checks && chip->can_sleep); status = chip->direction_output(chip, gpio, value); - if (status == 0) - set_bit(gpio, chip->is_out); + if (status) + desc->is_out = 1; return status; fail: spin_unlock_irqrestore(&gpio_lock, flags); @@ -363,27 +348,29 @@ EXPORT_SYMBOL_GPL(gpio_set_value_cansleep); #include #include - -static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) +static int gpiolib_show(struct seq_file *s, void *unused) { - unsigned i; + struct gpio_chip *chip; + unsigned id; - for (i = 0; i < chip->ngpio; i++) { - unsigned gpio; - int is_out; + /* REVISIT this isn't locked against gpio_chip removal ... */ - if (!chip->requested[i]) - continue; + seq_printf(s, "gpio chip_name requested direction value irq\n"); - gpio = chip->base + i; - is_out = test_bit(i, chip->is_out); + for (id = 0; id < ARCH_NR_GPIO; id++) { + struct gpio_desc *desc = &gpio_desc[id]; + struct gpio_chip *chip = desc->chip; + + if (chip == NULL) + continue; - seq_printf(s, " gpio-%-3d (%-12s) %s %s", - gpio, chip->requested[i], - is_out ? "out" : "in ", - chip->get - ? (chip->get(chip, i) ? "hi" : "lo") - : "? "); + seq_printf(s, " %3d %12s %9s %9s %5s", gpio, + chip->label, + desc->requested_label, + (desc->is_out) ? "out" : "in", + (chip->get) ? + (chip->get(chip, i) ? "hi" : "lo") + : "?"); if (!is_out) { int irq = gpio_to_irq(gpio); @@ -431,32 +418,6 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) seq_printf(s, "\n"); } -} - -static int gpiolib_show(struct seq_file *s, void *unused) -{ - struct gpio_chip *chip; - unsigned id; - int started = 0; - - /* REVISIT this isn't locked against gpio_chip removal ... */ - - for (id = 0; id < ARRAY_SIZE(chips); id++) { - chip = chips[id]; - if (!chip) - continue; - - seq_printf(s, "%sGPIOs %d-%d, %s%s:\n", - started ? "\n" : "", - chip->base, chip->base + chip->ngpio - 1, - chip->label ? : "generic", - chip->can_sleep ? ", can sleep" : ""); - started = 1; - if (chip->dbg_show) - chip->dbg_show(s, chip); - else - gpiolib_dbg_show(s, chip); - } return 0; } ------ >8 ------- On Nov 27, 2007 9:46 AM, David Brownell wrote: > On Tuesday 13 November 2007, David Brownell wrote: > > So the point of these is to make it easier for platforms > > (or even just boards) to make sure the GPIO number space > > is densely packed, rather than loosely so? Paying about > > 2KBytes for that privilege. (Assuming a 32 bit system > > with 256 GPIOs.) > > > > I could see that being a reasonable tradeoff. I wouldn't > > have started there myself, but you know how that goes! > > > > Does anyone else have any comments on that issue? > > Nobody else seems to have any comments on Eric's series > of patches to add a gpio_desc layer ... whereas, I was > looking at updating one platform, and got annoyed at some > stuff that would have been non-issues with them in place! > > > Eric, would you feel like rolling an all-in-one patch against > the gpiolib support from 2.6.24-rc3-mm? Including updated > versions of your patches: > > - [PATCH 2/5] define gpio_chip.requested_str > (renaming it as "label" to match its usage) > - [PATCH 3/5] use a per GPIO "struct gpio_desc" > (but without that needless list; for debug, > just scan the gpio_desc list for the next > non-null chip) > - [PATCH] move per GPIO "is_out" to "struct gpio_desc" > (i.e. patch 4/5) > - [PATCH 5/5] move per GPIO "requested" to "struct gpio_desc" > (and "label" too) > > along with removing the ARCH_GPIOS_PER_CHIP symbol, and > reducing ARCH_NR_GPIOS to a value which will waste less > space by default? (Like maybe 256.) > > I think an all-in-one patch will be easier to review > and agree on including (or not). > > - Dave > -- Cheers - eric