Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757587Ab1BRI5k (ORCPT ); Fri, 18 Feb 2011 03:57:40 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:35085 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751795Ab1BRI5h (ORCPT ); Fri, 18 Feb 2011 03:57:37 -0500 Date: Fri, 18 Feb 2011 09:57:34 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Peter Tyser Cc: linux-kernel@vger.kernel.org, Alek Du , Samuel Ortiz , David Brownell , Eric Miao , Mark Brown , Joe Perches , Alan Cox , Grant Likely Subject: Re: [PATCH v3 2/4] gpiolib: Add ability to get GPIO pin direction Message-ID: <20110218085734.GX22310@pengutronix.de> References: <1297983799-4747-1-git-send-email-ptyser@xes-inc.com> <1297983799-4747-2-git-send-email-ptyser@xes-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1297983799-4747-2-git-send-email-ptyser@xes-inc.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:215:17ff:fe12:23b0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4343 Lines: 116 On Thu, Feb 17, 2011 at 05:03:17PM -0600, Peter Tyser wrote: > Add a new get_direction() function to the gpio_chip structure. This is > useful so that the direction of a pin can be determined when its > initially exported. Previously, the direction defaulted to "unknown" > regardless of the actual configuration of the GPIO pin. > > If a GPIO driver implements get_direction(), it is called in > gpio_request() to set the initial direction of the pin accurately. IMHO the commit log is conceptually wrong, because it talks about a "pin". Better use gpio here. > Cc: Alek Du > Cc: Samuel Ortiz > Cc: David Brownell > Cc: Eric Miao > Cc: Uwe Kleine-K?nig > Cc: Mark Brown > Cc: Joe Perches > Cc: Alan Cox > Cc: Grant Likely > Signed-off-by: Peter Tyser > --- > Changes since v1: > - Add support for "unknown" direction > > Changes since v2: > Based on Wolfram's feedback: > - Use GPIOF_DIR_* flags as returns from get_direction() > - Call spin_lock_irqsave() to before setting flags > > drivers/gpio/gpiolib.c | 23 +++++++++++++++++++++++ > include/asm-generic/gpio.h | 4 ++++ > 2 files changed, 27 insertions(+), 0 deletions(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index eb74311..a656a2c 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -1174,6 +1174,7 @@ int gpio_request(unsigned gpio, const char *label) > struct gpio_desc *desc; > struct gpio_chip *chip; > int status = -EINVAL; > + int dir; > unsigned long flags; > > spin_lock_irqsave(&gpio_lock, flags); > @@ -1214,6 +1215,28 @@ int gpio_request(unsigned gpio, const char *label) > } > } > > + if (chip->get_direction) { > + /* chip->get_direction may sleep */ > + spin_unlock_irqrestore(&gpio_lock, flags); might_sleep_if(chip->can_sleep) ? > + dir = chip->get_direction(chip, gpio - chip->base); > + spin_lock_irqsave(&gpio_lock, flags); > + switch (dir) { > + case GPIOF_DIR_OUT: > + set_bit(FLAG_DIR_OUT, &desc->flags); > + clear_bit(FLAG_DIR_IN, &desc->flags); > + break; > + case GPIOF_DIR_IN: > + set_bit(FLAG_DIR_IN, &desc->flags); > + clear_bit(FLAG_DIR_OUT, &desc->flags); > + break; > + default: > + /* Direction isn't known */ > + clear_bit(FLAG_DIR_OUT, &desc->flags); > + clear_bit(FLAG_DIR_IN, &desc->flags); > + break; > + } Alternatively to my suggestion for patch1: } else { clear_bit(FLAG_DIR_OUT, &desc->flags); clear_bit(FLAG_DIR_IN, &desc->flags); > + } > + > done: > if (status) > pr_debug("gpio_request: gpio-%d (%s) status %d\n", > diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h > index ff5c660..6af5a3e 100644 > --- a/include/asm-generic/gpio.h > +++ b/include/asm-generic/gpio.h > @@ -57,6 +57,8 @@ struct device_node; > * @direction_input: configures signal "offset" as input, or returns error > * @get: returns value for signal "offset"; for output signals this > * returns either the value actually sensed, or zero > + * @get_direction: optional hook to determine if a GPIO signal is configured > + * as an input, output, or unknown > * @direction_output: configures signal "offset" as output, or returns error > * @set: assigns output value for signal "offset" > * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; > @@ -101,6 +103,8 @@ struct gpio_chip { > unsigned offset); > int (*get)(struct gpio_chip *chip, > unsigned offset); > + int (*get_direction)(struct gpio_chip *chip, > + unsigned offset); > int (*direction_output)(struct gpio_chip *chip, > unsigned offset, int value); > int (*set_debounce)(struct gpio_chip *chip, > -- > 1.7.0.4 > > -- Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ | -- 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/