Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753963Ab0BIJSM (ORCPT ); Tue, 9 Feb 2010 04:18:12 -0500 Received: from mail-fx0-f220.google.com ([209.85.220.220]:38112 "EHLO mail-fx0-f220.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753866Ab0BIJSG (ORCPT ); Tue, 9 Feb 2010 04:18:06 -0500 Message-ID: <4B7127AC.9020600@petalogix.com> Date: Tue, 09 Feb 2010 10:15:24 +0100 From: Michal Simek Reply-To: michal.simek@petalogix.com User-Agent: Thunderbird 2.0.0.22 (X11/20090625) MIME-Version: 1.0 To: Anton Vorontsov CC: Grant Likely , David Brownell , Benjamin Herrenschmidt , David Miller , Michal Simek , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, microblaze-uclinux@itee.uq.edu.au Subject: Re: [PATCH 3/3] of/gpio: Introduce of_put_gpio(), add ref counting for OF GPIO chips References: <20100205204949.GA2575@oksana.dev.rtsoft.ru> <20100205205045.GC4178@oksana.dev.rtsoft.ru> In-Reply-To: <20100205205045.GC4178@oksana.dev.rtsoft.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7571 Lines: 254 Anton Vorontsov wrote: > OF GPIO infrastructure is using dynamic GPIO bases, so it is possible > that of_get_gpio()'s returned GPIO number will be no longer valid, or > worse, it may point to an unexpected GPIO controller. I am not able to apply this last patch. $ git-am < \[PATCH\ 3_3\]\ of_gpio\:\ Introduce\ of_put_gpio\(\)\,\ add\ ref\ counting\ for\ OF\ GPIO\ chips.eml Applying of/gpio: Introduce of_put_gpio(), add ref counting for OF GPIO chips error: patch failed: drivers/of/gpio.c:254 error: drivers/of/gpio.c: patch does not apply Patch failed at 0001. When you have resolved this problem run "git-am --resolved". If you would prefer to skip this patch, instead run "git-am --skip". Below is my git-log which patches I applied. Please fix it. Thanks, Michal 99d5baaa53562252a896080bf426b4ae71a5e55f of: Introduce safe accessors for node->data df6d71af9c0691716ad8a368609a7e26a8dfdaa0 of platforms: Move common static initialization to of_node_init() 566969302a9dd70ce8a07c978bd08804ee73d0d6 powerpc/mcu_mpc8349emitx: Remove OF GPIO handling stuff 816932ea74919867c1f899758ea4cdd138145453 of/gpio: Implement GPIOLIB notifier hooks 3ea035a9e0f446b2b9cd9bacf73395a0c80ae3e9 of/gpio: Implement GPIOLIB notifier hooks b7b96a9ee215c800476d002b06a338c4499f3813 of/gpio: Add support for two-stage registration for the of_gpio_chips 15678cc192c03a2b1bbb36da18ff2a3fe2d78897 gpiolib: Introduce chip addition/removal notifier deb0c98c7f6035d47a247e548384517a955314a5 Merge branch 'for-2.6.33' of git://linux-nfs.org/~bfields/linux > > This scenario is possible: > > driver A: driver B: driver C: > --------- --------- --------- > gpiochip_add() > gpio = of_get_gpio() > gpiochip_remove() > gpiochip_add() > gpio_request(gpio); > gpio_set_value(gpio); > > That is, driver A assumes that it is working with GPIO from driver B, > but in practice it may disappear and driver C will take its GPIO base > number, so it will provide the same GPIO numbers. > > With this patch that situation is no longer possible. Though drivers > will need to learn to put GPIOs back, so that GPIO controllers could > be removed. > > Signed-off-by: Anton Vorontsov > --- > drivers/of/gpio.c | 82 ++++++++++++++++++++++++++++++++++++++++------- > include/linux/of_gpio.h | 5 +++ > 2 files changed, 75 insertions(+), 12 deletions(-) > > diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c > index 9d8df77..e94c5c8 100644 > --- a/drivers/of/gpio.c > +++ b/drivers/of/gpio.c > @@ -28,6 +28,8 @@ > * Returns GPIO number to use with Linux generic GPIO API, or one of the errno > * value on the error condition. If @flags is not NULL the function also fills > * in flags for the GPIO. > + * > + * Remeber to put the GPIO back using of_put_gpio() call. > */ > int of_get_gpio_flags(struct device_node *np, int index, > enum of_gpio_flags *flags) > @@ -46,6 +48,8 @@ int of_get_gpio_flags(struct device_node *np, int index, > goto err0; > } > > + spin_lock(&gc->data_lock); > + > of_gc = gc->data; > if (!of_gc) { > pr_debug("%s: gpio controller %s isn't registered\n", > @@ -72,15 +76,62 @@ int of_get_gpio_flags(struct device_node *np, int index, > goto err1; > > ret += of_gc->chip->base; > + > + if (!try_module_get(of_gc->chip->owner)) { > + ret = -EINVAL; > + goto err1; > + } > + > + of_gc->refcnt++; > err1: > + spin_unlock(&gc->data_lock); > + > of_node_put(gc); > err0: > pr_debug("%s exited with status %d\n", __func__, ret); > + > return ret; > } > EXPORT_SYMBOL(of_get_gpio_flags); > > /** > + * of_put_gpio - Put a GPIO back to the OF subsystem > + * @np: device node of the GPIO owner > + * @index: index of the GPIO > + */ > +static inline void of_put_gpio(struct device_node *np, int index) > +{ > + int ret; > + struct device_node *gc; > + struct of_gpio_chip *of_gc; > + > + ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index, > + &gc, NULL); > + if (ret) { > + pr_debug("%s: can't parse gpios property\n", __func__); > + return; > + } > + > + spin_lock(&gc->data_lock); > + > + of_gc = gc->data; > + if (!of_gc) { > + pr_debug("%s: gpio controller %s isn't registered\n", > + np->full_name, gc->full_name); > + goto err; > + } > + > + if (of_gc->refcnt) > + of_gc->refcnt--; > + else > + WARN_ON(1); > + > + module_put(of_gc->chip->owner); > +err: > + spin_unlock(&gc->data_lock); > +} > + > +/** > * of_gpio_count - Count GPIOs for a device > * @np: device node to count GPIOs for > * > @@ -254,11 +305,7 @@ static int of_gpiochip_register_simple(struct gpio_chip *chip, > struct device_node *np) > { > struct of_gpio_chip *of_gc; > - > - if (np->data) { > - WARN_ON(1); > - return -EBUSY; > - } > + int ret; > > of_gc = kzalloc(sizeof(*of_gc), GFP_KERNEL); > if (!of_gc) > @@ -267,10 +314,12 @@ static int of_gpiochip_register_simple(struct gpio_chip *chip, > of_gc->gpio_cells = 2; > of_gc->xlate = of_gpio_simple_xlate; > of_gc->chip = chip; > - np->data = of_gc; > - of_node_get(np); > > - return 0; > + ret = of_node_set_data(np, of_gc); > + if (ret) > + kfree(of_gc); > + > + return ret; > } > EXPORT_SYMBOL(of_gpiochip_register_simple); > > @@ -286,17 +335,26 @@ static int of_gpiochip_unregister(struct gpio_chip *chip, > struct device_node *np) > { > struct of_gpio_chip *of_gc = np->data; > + int ret = 0; > > if (!of_gc || of_gc->chip != chip) { > WARN_ON(1); > return -EINVAL; > } > > - np->data = NULL; > - kfree(of_gc); > - of_node_put(np); > + spin_lock(&np->data_lock); > > - return 0; > + if (of_gc->refcnt) > + ret = -EBUSY; > + else > + of_node_release_data_unlocked(np); > + > + spin_unlock(&np->data_lock); > + > + if (!ret) > + kfree(of_gc); > + > + return ret; > } > > static int of_gpio_notify(struct notifier_block *nb, unsigned long msg, > diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h > index c74cb37..aca7ab1 100644 > --- a/include/linux/of_gpio.h > +++ b/include/linux/of_gpio.h > @@ -38,6 +38,7 @@ enum of_gpio_flags { > struct of_gpio_chip { > struct gpio_chip gc; /* legacy, don't use for a new code */ > struct gpio_chip *chip; > + unsigned int refcnt; > int gpio_cells; > int (*xlate)(struct of_gpio_chip *of_gc, struct device_node *np, > const void *gpio_spec, enum of_gpio_flags *flags); > @@ -83,6 +84,8 @@ static inline int of_get_gpio_flags(struct device_node *np, int index, > return -ENOSYS; > } > > +static inline void of_put_gpio(struct device_node *np, int index) {} > + > static inline unsigned int of_gpio_count(struct device_node *np) > { > return 0; > @@ -97,6 +100,8 @@ static inline unsigned int of_gpio_count(struct device_node *np) > * > * Returns GPIO number to use with Linux generic GPIO API, or one of the errno > * value on the error condition. > + * > + * Remeber to put the GPIO back using of_put_gpio() call. > */ > static inline int of_get_gpio(struct device_node *np, int index) > { -- Michal Simek, Ing. (M.Eng) PetaLogix - Linux Solutions for a Reconfigurable World w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/