From patchwork Tue Jun 24 23:57:28 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shuah Khan X-Patchwork-Id: 4414891 Return-Path: X-Original-To: patchwork-linux-media@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 92FC29F1D6 for ; Tue, 24 Jun 2014 23:57:58 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6B023202E9 for ; Tue, 24 Jun 2014 23:57:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AE5E20120 for ; Tue, 24 Jun 2014 23:57:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753729AbaFXX5y (ORCPT ); Tue, 24 Jun 2014 19:57:54 -0400 Received: from qmta09.emeryville.ca.mail.comcast.net ([76.96.30.96]:51039 "EHLO qmta09.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205AbaFXX5w (ORCPT ); Tue, 24 Jun 2014 19:57:52 -0400 Received: from omta07.emeryville.ca.mail.comcast.net ([76.96.30.59]) by qmta09.emeryville.ca.mail.comcast.net with comcast id JPve1o0031GXsucA9PxsCM; Tue, 24 Jun 2014 23:57:52 +0000 Received: from mail.gonehiking.org ([50.134.149.16]) by omta07.emeryville.ca.mail.comcast.net with comcast id JPxp1o00t0MU7Qa8UPxqti; Tue, 24 Jun 2014 23:57:51 +0000 Received: from lorien.sisa.samsung.com (lorien-wl.internal [192.168.1.40]) by mail.gonehiking.org (Postfix) with ESMTP id 7D64340885; Tue, 24 Jun 2014 17:57:49 -0600 (MDT) From: Shuah Khan To: gregkh@linuxfoundation.org, m.chehab@samsung.com, olebowle@gmx.com, ttmesterr@gmail.com, dheitmueller@kernellabs.com, cb.xiong@samsung.com, yongjun_wei@trendmicro.com.cn, hans.verkuil@cisco.com, prabhakar.csengg@gmail.com, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, crope@iki.fi, wade_farnsworth@mentor.com, ricardo.ribalda@gmail.com Cc: Shuah Khan , linux-media@vger.kernel.org Subject: [PATCH 1/4] drivers/base: add managed token dev resource Date: Tue, 24 Jun 2014 17:57:28 -0600 Message-Id: X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1403654272; bh=tKn3ufEezZj6PovsIzYtrbfmPmalj6vF29jdpoN9roo=; h=Received:Received:Received:From:To:Subject:Date:Message-Id; b=S9ZN2Wpj51PH3sVTiV1laOGGKSY1ddo7aTPsU4380F81+AndiuYoJWkB8VvTSfeL4 n7OJFQusY6b0TZJ0V/bmMoV7UFviw+Pq+3Hj54J6vVzJpfiVU11buJD/CzrZaKoGaE QU6T8D01Gqf1bd0O43X9AV8gBoJCGjrZpkripFtIzwOI8l3F2M21KvhXTpkwEiVQlY lnqURckdvqQvmYKPerDF2e/jMa1eSwTGillNrVRS+eaU/8ZEO3UCKpCdxYZmXZx0t/ QfxQY8JSzpmUVj5MHuUpukK3PkcE+YIFPhsINyoX484gxL8ID0o+hMcJo0qXvWDA0/ d7vXGStmLOSEQ== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID,T_RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add a managed token resource that can be created at device level which can be used as a large grain lock by diverse group of drivers such as the media drivers that share a resource. Media devices often have hardware resources that are shared across several functions. These devices appear as a group of independent devices. Each device implements a function which could be shared by one or more functions supported by the same device. For example, tuner is shared by analog and digital TV functions. Media drivers that control a single media TV stick are a diversified group. Analog and digital TV function drivers have to coordinate access to their shared functions. Some media devices provide multiple almost-independent functions. USB and PCI core aids in allowing multiple drivers to handle these almost-independent functions. In this model, a media device could have snd-usb-audio driving the audio function. As a result, snd-usb-audio driver has to coordinate with the media driver analog and digital function drivers. A shared managed resource framework at drivers/base level will allow a media device to be controlled by drivers that don't fall under drivers/media and share functions with other media drivers. Token resource manages a unique named string resource which is derived from common bus_name, and hardware address fields from the struct device. Interfaces: devm_token_create() devm_token_destroy() devm_token_lock() devm_token_unlock() Usage: Create token: Call devm_token_create() with a token id string. Lock token: Call devm_token_lock() to lock or try lock a token. Unlock token: Call devm_token_unlock(). Destroy token: Call devm_token_destroy() to delete the token. Signed-off-by: Shuah Khan --- drivers/base/Makefile | 2 +- drivers/base/token_devres.c | 134 ++++++++++++++++++++++++++++++++++++++++++ include/linux/token_devres.h | 19 ++++++ 3 files changed, 154 insertions(+), 1 deletion(-) create mode 100644 drivers/base/token_devres.c create mode 100644 include/linux/token_devres.h diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 04b314e..924665b 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -4,7 +4,7 @@ obj-y := component.o core.o bus.o dd.o syscore.o \ driver.o class.o platform.o \ cpu.o firmware.o init.o map.o devres.o \ attribute_container.o transport_class.o \ - topology.o container.o + topology.o container.o token_devres.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o obj-$(CONFIG_DMA_CMA) += dma-contiguous.o obj-y += power/ diff --git a/drivers/base/token_devres.c b/drivers/base/token_devres.c new file mode 100644 index 0000000..86bcd25 --- /dev/null +++ b/drivers/base/token_devres.c @@ -0,0 +1,134 @@ +/* + * drivers/base/token_devres.c - managed token resource + * + * Copyright (c) 2014 Shuah Khan + * Copyright (c) 2014 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + */ +/* + * Media devices often have hardware resources that are shared + * across several functions. For instance, TV tuner cards often + * have MUXes, converters, radios, tuners, etc. that are shared + * across various functions. However, v4l2, alsa, DVB, usbfs, and + * all other drivers have no knowledge of what resources are + * shared. For example, users can't access DVB and alsa at the same + * time, or the DVB and V4L analog API at the same time, since many + * only have one converter that can be in either analog or digital + * mode. Accessing and/or changing mode of a converter while it is + * in use by another function results in video stream error. + * + * A shared devres that can be locked and unlocked by various drivers + * that control media functions on a single media device is needed to + * address the above problems. + * + * A token devres that can be looked up by a token for locking, try + * locking, unlocking will help avoid adding data structure + * dependencies between various media drivers. This token is a unique + * string that can be constructed from a common data structure such as + * struct device, bus_name, and hardware address. + * + * The devm_token_* interfaces manage access to token resource. + * + * Interfaces: + * devm_token_create() + * devm_token_destroy() + * devm_token_lock() + * devm_token_unlock() + * Usage: + * Create token: + * Call devm_token_create() with a token id which is + * a unique string. + * Lock token: + * Call devm_token_lock() to lock or try lock a token. + * Unlock token: + * Call devm_token_unlock(). + * Destroy token: + * Call devm_token_destroy() to delete the token. + * +*/ +#include +#include + +struct token_devres { + struct mutex lock; + char id[]; +}; + +static int devm_token_match(struct device *dev, void *res, void *data) +{ + struct token_devres *tkn = res; + + /* compare the token data and return 1 if it matches */ + return !strcmp(tkn->id, data); +} + +static void devm_token_release(struct device *dev, void *res) +{ + struct token_devres *tkn = res; + + mutex_destroy(&tkn->lock); +} + +/* creates a token devres and marks it available */ +int devm_token_create(struct device *dev, const char *id) +{ + struct token_devres *tkn; + size_t tkn_size; + + tkn_size = sizeof(struct token_devres) + strlen(id) + 1; + tkn = devres_alloc(devm_token_release, tkn_size, GFP_KERNEL); + if (!tkn) + return -ENOMEM; + + strcpy(tkn->id, id); + mutex_init(&tkn->lock); + + devres_add(dev, tkn); + return 0; +} +EXPORT_SYMBOL_GPL(devm_token_create); + +/* If token is available, lock it for the caller, If not return -EBUSY */ +int devm_token_lock(struct device *dev, const char *id) +{ + struct token_devres *tkn_ptr; + + tkn_ptr = devres_find(dev, devm_token_release, devm_token_match, + (void *)id); + if (tkn_ptr == NULL) + return -ENODEV; + + if (!mutex_trylock(&tkn_ptr->lock)) + return -EBUSY; + return 0; +} +EXPORT_SYMBOL_GPL(devm_token_lock); + +/* If token is locked, unlock */ +int devm_token_unlock(struct device *dev, const char *id) +{ + struct token_devres *tkn_ptr; + + tkn_ptr = devres_find(dev, devm_token_release, devm_token_match, + (void *) id); + if (tkn_ptr == NULL) + return -ENODEV; + + mutex_unlock(&tkn_ptr->lock); + return 0; +} +EXPORT_SYMBOL_GPL(devm_token_unlock); + +/* destroy an existing token */ +int devm_token_destroy(struct device *dev, const char *id) +{ + int rc; + + rc = devres_release(dev, devm_token_release, devm_token_match, + (void *) id); + WARN_ON(rc); + + return 0; +} +EXPORT_SYMBOL_GPL(devm_token_destroy); diff --git a/include/linux/token_devres.h b/include/linux/token_devres.h new file mode 100644 index 0000000..e411fd5 --- /dev/null +++ b/include/linux/token_devres.h @@ -0,0 +1,19 @@ +/* + * token_devres.h - managed token resource + * + * Copyright (c) 2014 Shuah Khan + * Copyright (c) 2014 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + */ +#ifndef __LINUX_TOKEN_DEVRES_H +#define __LINUX_TOKEN_DEVRES_H + +struct device; + +extern int devm_token_create(struct device *dev, const char *id); +extern int devm_token_lock(struct device *dev, const char *id); +extern int devm_token_unlock(struct device *dev, const char *id); +extern int devm_token_destroy(struct device *dev, const char *id); + +#endif /* __LINUX_TOKEN_DEVRES_H */