Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753984AbXJWU41 (ORCPT ); Tue, 23 Oct 2007 16:56:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752571AbXJWU4A (ORCPT ); Tue, 23 Oct 2007 16:56:00 -0400 Received: from atlrel7.hp.com ([156.153.255.213]:34483 "EHLO atlrel7.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752367AbXJWUz7 (ORCPT ); Tue, 23 Oct 2007 16:55:59 -0400 Message-Id: <20071023205515.775882722@ldl.fc.hp.com> References: <20071023204843.442608289@ldl.fc.hp.com> User-Agent: quilt/0.45-1 Date: Tue, 23 Oct 2007 14:48:45 -0600 From: Bjorn Helgaas To: Alessandro Zummo Cc: Andrew Morton Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Subject: [patch 2/2] rtc: fallback to requesting only the ports we actually use Content-Disposition: inline; filename=rtc-resource-size Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3099 Lines: 104 Firmware like PNPBIOS or ACPI can report the address space consumed by the RTC. The actual space consumed may be less than the size (RTC_IO_EXTENT) assumed by the RTC driver. The PNP core doesn't request resources yet, but I'd like to make it do so. If/when it does, the RTC_IO_EXTENT request may fail, which prevents the RTC driver from loading. Since we only use the RTC index and data registers at RTC_PORT(0) and RTC_PORT(1), we can fall back to requesting just enough space for those. If the PNP core requests resources, this results in typical I/O port usage like this: 0070-0073 : 00:06 <-- PNP device 00:06 responds to 70-73 0070-0071 : rtc <-- RTC driver uses only 70-71 instead of the current: 0070-0077 : rtc <-- RTC_IO_EXTENT == 8 Signed-off-by: Bjorn Helgaas Index: w/drivers/char/rtc.c =================================================================== --- w.orig/drivers/char/rtc.c 2007-10-23 14:41:23.000000000 -0600 +++ w/drivers/char/rtc.c 2007-10-23 14:41:30.000000000 -0600 @@ -918,12 +918,29 @@ }; #endif +static resource_size_t rtc_size; + +static struct resource * __init rtc_request_region(resource_size_t size) +{ + struct resource *r; + + if (RTC_IOMAPPED) + r = request_region(RTC_PORT(0), size, "rtc"); + else + r = request_mem_region(RTC_PORT(0), size, "rtc"); + + if (r) + rtc_size = size; + + return r; +} + static void rtc_release_region(void) { if (RTC_IOMAPPED) - release_region(RTC_PORT(0), RTC_IO_EXTENT); + release_region(RTC_PORT(0), rtc_size); else - release_mem_region(RTC_PORT(0), RTC_IO_EXTENT); + release_mem_region(RTC_PORT(0), rtc_size); } static int __init rtc_init(void) @@ -976,10 +993,17 @@ } no_irq: #else - if (RTC_IOMAPPED) - r = request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc"); - else - r = request_mem_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc"); + r = rtc_request_region(RTC_IO_EXTENT); + + /* + * If we've already requested a smaller range (for example, because + * PNPBIOS or ACPI told us how the device is configured), the request + * above might fail because it's too big. + * + * If so, request just the range we actually use. + */ + if (!r) + r = rtc_request_region(RTC_IO_EXTENT_USED); if (!r) { #ifdef RTC_IRQ rtc_has_irq = 0; Index: w/include/linux/mc146818rtc.h =================================================================== --- w.orig/include/linux/mc146818rtc.h 2007-10-23 14:41:23.000000000 -0600 +++ w/include/linux/mc146818rtc.h 2007-10-23 14:41:30.000000000 -0600 @@ -109,8 +109,11 @@ #ifndef ARCH_RTC_LOCATION /* Override by ? */ #define RTC_IO_EXTENT 0x8 +#define RTC_IO_EXTENT_USED 0x2 #define RTC_IOMAPPED 1 /* Default to I/O mapping. */ +#else +#define RTC_IO_EXTENT_USED RTC_IO_EXTENT #endif /* ARCH_RTC_LOCATION */ #endif /* _MC146818RTC_H */ -- - 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/