Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754458AbYCKRll (ORCPT ); Tue, 11 Mar 2008 13:41:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752699AbYCKRlW (ORCPT ); Tue, 11 Mar 2008 13:41:22 -0400 Received: from rtsoft3.corbina.net ([85.21.88.6]:24411 "EHLO buildserver.ru.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752676AbYCKRlU (ORCPT ); Tue, 11 Mar 2008 13:41:20 -0400 Date: Tue, 11 Mar 2008 20:41:16 +0300 From: Anton Vorontsov To: David Brownell Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH 1/3] gpiolib: implement dynamic base allocation Message-ID: <20080311174116.GA12397@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Disposition: inline User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2711 Lines: 99 If gpio_chip->base is negative during registration, gpiolib requests dynamic base allocation. This is useful for devices being registered at run-time (in contrast to platform devices). To avoid reusing any numbers that may have been explicitly assigned, but not yet registered, dynamic gpio base allocator will assign GPIO numbers from the biggest number on down, instead of from the smallest on up. Signed-off-by: Anton Vorontsov --- Rebased on top of v2.6.25-rc3-mm1 drivers/gpio/gpiolib.c | 43 ++++++++++++++++++++++++++++++++++++++----- 1 files changed, 38 insertions(+), 5 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 623fcd9..81d81c9 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -80,6 +80,33 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio) return gpio_desc[gpio].chip; } +static int gpiochip_find_base(int ngpio) +{ + int i; + int spare = 0; + int base = -ENOSPC; + + for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) { + struct gpio_chip *chip = gpio_desc[i].chip; + + if (!chip) { + spare++; + if (spare == ngpio) { + base = i; + break; + } + } else { + spare = 0; + i -= chip->ngpio - 1; + } + } + + if (gpio_is_valid(base)) + pr_debug("%s: found new base at %d\n", __func__, base); + + return base; +} + /** * gpiochip_add() - register a gpio_chip * @chip: the chip to register, with chip->base initialized @@ -95,17 +122,22 @@ int gpiochip_add(struct gpio_chip *chip) int status = 0; unsigned id; - /* NOTE chip->base negative is reserved to mean a request for - * dynamic allocation. We don't currently support that. - */ - - if (chip->base < 0 || !gpio_is_valid(chip->base + chip->ngpio)) { + if (gpio_is_valid(chip->base) && + !gpio_is_valid(chip->base + chip->ngpio)) { status = -EINVAL; goto fail; } spin_lock_irqsave(&gpio_lock, flags); + if (!gpio_is_valid(chip->base)) { + chip->base = gpiochip_find_base(chip->ngpio); + if (!gpio_is_valid(chip->base)) { + status = chip->base; + goto fail_unlock; + } + } + /* these GPIO numbers must not be managed by another gpio_chip */ for (id = chip->base; id < chip->base + chip->ngpio; id++) { if (gpio_desc[id].chip != NULL) { @@ -120,6 +152,7 @@ int gpiochip_add(struct gpio_chip *chip) } } +fail_unlock: spin_unlock_irqrestore(&gpio_lock, flags); fail: /* failures here can mean systems won't boot... */ -- 1.5.2.2 -- 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/