Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753778Ab1DNVjF (ORCPT ); Thu, 14 Apr 2011 17:39:05 -0400 Received: from smtp-out.google.com ([216.239.44.51]:42382 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753126Ab1DNVjB (ORCPT ); Thu, 14 Apr 2011 17:39:01 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=GeBBkqDDBkDOCmwKQdfoTYKrZ5EstBm6xotJSjvOqGXa3kVLTl4yMgiIAgBKXCRXa HHGWZrPha7vDog125xsSA== From: Nat Gurumoorthy To: Jean Delvare , Guenter Roeck , Wim Van Sebroeck Cc: Mike Waychison , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org, Nat Gurumoorthy Subject: [PATCH v6 2/2] Use "request_muxed_region" in it87 hwmon drivers Date: Thu, 14 Apr 2011 14:38:16 -0700 Message-Id: <1302817096-6433-1-git-send-email-natg@google.com> X-Mailer: git-send-email 1.7.3.1 In-Reply-To: <1302816996-6345-1-git-send-email-natg@google.com> References: <1302816996-6345-1-git-send-email-natg@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2035 Lines: 80 02 - Chages to hwmon it87 driver to use "request_muxed_region" Serialize access to the hardware by using "request_muxed_region" macro defined by Alan Cox. Call to this macro will hold off the requestor if the resource is currently busy. The first call to request_muxed_region will attempt 10 times to reserve the region before it gives up. This will typically get called from the driver init routines. If this succeeds then subsequent calls wait forever for the resource to be available. Signed-off-by: Nat Gurumoorthy --- diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c index 316b648..2c349be 100644 --- a/drivers/hwmon/it87.c +++ b/drivers/hwmon/it87.c @@ -108,13 +108,34 @@ superio_select(int ldn) outb(ldn, VAL); } -static inline void -superio_enter(void) -{ +static inline int +try_superio_enter(void) +{ + int num_tries = 10; + /* + * Try to reserve REG and REG + 1 for exclusive access. + * Give up after 10 attempts. + */ + while (num_tries--) { + if (!request_muxed_region(REG, 2, DRVNAME)) { + if (num_tries) + continue; + + /* + * Someone is holding the region. Give up. + */ + pr_err("I/O address 0x%04x already in use\n", REG); + return -EBUSY; + } + + break; + } + outb(0x87, REG); outb(0x01, REG); outb(0x55, REG); outb(0x55, REG); + return 0; } static inline void @@ -122,6 +143,7 @@ superio_exit(void) { outb(0x02, REG); outb(0x02, VAL); + release_region(REG, 2); } /* Logical device 4 registers */ @@ -1546,7 +1568,9 @@ static int __init it87_find(unsigned short *address, u16 chip_type; const char *board_vendor, *board_name; - superio_enter(); + if (try_superio_enter()) + return -EBUSY; + chip_type = force_id ? force_id : superio_inw(DEVID); switch (chip_type) { -- 1.7.3.1 -- 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/