From patchwork Tue Mar 12 16:03:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guennadi Liakhovetski X-Patchwork-Id: 2257091 Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 88CA3DF23A for ; Tue, 12 Mar 2013 16:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932709Ab3CLQDg (ORCPT ); Tue, 12 Mar 2013 12:03:36 -0400 Received: from moutng.kundenserver.de ([212.227.126.187]:49175 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932706Ab3CLQDg (ORCPT ); Tue, 12 Mar 2013 12:03:36 -0400 Received: from axis700.grange (dslb-094-221-122-231.pools.arcor-ip.net [94.221.122.231]) by mrelayeu.kundenserver.de (node=mrbap3) with ESMTP (Nemesis) id 0Lm4GH-1UoVJ50Csz-00ZdYg; Tue, 12 Mar 2013 17:03:22 +0100 Received: by axis700.grange (Postfix, from userid 1000) id 8125940BB4; Tue, 12 Mar 2013 17:03:21 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by axis700.grange (Postfix) with ESMTP id 7D8B140BB3; Tue, 12 Mar 2013 17:03:21 +0100 (CET) Date: Tue, 12 Mar 2013 17:03:21 +0100 (CET) From: Guennadi Liakhovetski X-X-Sender: lyakh@axis700.grange To: Linux Media Mailing List cc: Laurent Pinchart , Sakari Ailus , Hans Verkuil , Sylwester Nawrocki , Magnus Damm , linux-sh@vger.kernel.org, Sylwester Nawrocki Subject: [PATCH v4] media: V4L2: add temporary clock helpers Message-ID: MIME-Version: 1.0 X-Provags-ID: V02:K0:aY1g2HKczpNrSH/BbBCLtn7YpnYhY4G2Y3RCpcWQW/v 1BJ6yPqBkwRZE/olcg7L68G470Or0PzYkbrrbEiZx4mIy5e8Sk Ra+USH7bfMR6k97mGlgVO9N4Le3yzySx4i0Mfw+MpmUcVbvqlj xZPiITQh7UpMpqdsSMyEh6kBvE0wU3nRti5bFrkIrkPXAzsy6G Pxu8njadgWPaTkWJ5MN2iyxMIxIpSx9prN7c30b5gm2g1ipxe1 pIktlpDrKobfuHCkB9vV88IpTW7Vo+P4KNOBlR8/iV6W4nmPVZ 1h2nB/7URJbAH2l7mp1/mhaR0Pgq8rJa6itR/8wCDuBczktbxB H0vjAUDHOHyBKKBE2dj5axmuON1E2v6gz8QcmpHr7BYIIeHR9j xc7v5vk4QLIDQ== Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Typical video devices like camera sensors require an external clock source. Many such devices cannot even access their hardware registers without a running clock. These clock sources should be controlled by their consumers. This should be performed, using the generic clock framework. Unfortunately so far only very few systems have been ported to that framework. This patch adds a set of temporary helpers, mimicking the generic clock API, to V4L2. Platforms, adopting the clock API, should switch to using it. Eventually this temporary API should be removed. Signed-off-by: Guennadi Liakhovetski --- v4: replace BUG() with a WARN_ON() - thanks to Sylwester for a geads-up drivers/media/v4l2-core/Makefile | 2 +- drivers/media/v4l2-core/v4l2-clk.c | 175 ++++++++++++++++++++++++++++++++++++ include/media/v4l2-clk.h | 54 +++++++++++ 3 files changed, 230 insertions(+), 1 deletions(-) create mode 100644 drivers/media/v4l2-core/v4l2-clk.c create mode 100644 include/media/v4l2-clk.h diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile index a9d3552..aea7aea 100644 --- a/drivers/media/v4l2-core/Makefile +++ b/drivers/media/v4l2-core/Makefile @@ -5,7 +5,7 @@ tuner-objs := tuner-core.o videodev-objs := v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \ - v4l2-event.o v4l2-ctrls.o v4l2-subdev.o + v4l2-event.o v4l2-ctrls.o v4l2-subdev.o v4l2-clk.o ifeq ($(CONFIG_COMPAT),y) videodev-objs += v4l2-compat-ioctl32.o endif diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c new file mode 100644 index 0000000..9c714a7 --- /dev/null +++ b/drivers/media/v4l2-core/v4l2-clk.c @@ -0,0 +1,175 @@ +/* + * V4L2 clock service + * + * Copyright (C) 2012, Guennadi Liakhovetski + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include + +#include +#include + +static DEFINE_MUTEX(clk_lock); +static LIST_HEAD(clk_list); + +static struct v4l2_clk *v4l2_clk_find(const char *dev_id, const char *id) +{ + struct v4l2_clk *clk; + + list_for_each_entry(clk, &clk_list, list) { + if (strcmp(dev_id, clk->dev_id)) + continue; + + if (!id || !clk->id || !strcmp(clk->id, id)) + return clk; + } + + return ERR_PTR(-ENODEV); +} + +struct v4l2_clk *v4l2_clk_get(struct v4l2_subdev *sd, const char *id) +{ + struct v4l2_clk *clk; + + mutex_lock(&clk_lock); + clk = v4l2_clk_find(sd->name, id); + + if (!IS_ERR(clk) && !try_module_get(clk->ops->owner)) + clk = ERR_PTR(-ENODEV); + mutex_unlock(&clk_lock); + + if (!IS_ERR(clk)) + atomic_inc(&clk->use_count); + + return clk; +} +EXPORT_SYMBOL(v4l2_clk_get); + +void v4l2_clk_put(struct v4l2_clk *clk) +{ + if (!IS_ERR(clk)) { + atomic_dec(&clk->use_count); + module_put(clk->ops->owner); + } +} +EXPORT_SYMBOL(v4l2_clk_put); + +int v4l2_clk_enable(struct v4l2_clk *clk) +{ + int ret; + mutex_lock(&clk->lock); + if (++clk->enable == 1 && clk->ops->enable) { + ret = clk->ops->enable(clk); + if (ret < 0) + clk->enable--; + } else { + ret = 0; + } + mutex_unlock(&clk->lock); + return ret; +} +EXPORT_SYMBOL(v4l2_clk_enable); + +void v4l2_clk_disable(struct v4l2_clk *clk) +{ + int enable; + + mutex_lock(&clk->lock); + enable = --clk->enable; + if (WARN(enable < 0, "Unbalanced %s() on %s:%s!\n", __func__, + clk->dev_id, clk->id)) + clk->enable++; + else if (!enable && clk->ops->disable) + clk->ops->disable(clk); + mutex_unlock(&clk->lock); +} +EXPORT_SYMBOL(v4l2_clk_disable); + +unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk) +{ + if (!clk->ops->get_rate) + return -ENOSYS; + + return clk->ops->get_rate(clk); +} +EXPORT_SYMBOL(v4l2_clk_get_rate); + +int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate) +{ + if (!clk->ops->set_rate) + return -ENOSYS; + + return clk->ops->set_rate(clk, rate); +} +EXPORT_SYMBOL(v4l2_clk_set_rate); + +struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops, + const char *dev_id, + const char *id, void *priv) +{ + struct v4l2_clk *clk; + int ret; + + if (!ops || !dev_id) + return ERR_PTR(-EINVAL); + + clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL); + if (!clk) + return ERR_PTR(-ENOMEM); + + clk->id = kstrdup(id, GFP_KERNEL); + clk->dev_id = kstrdup(dev_id, GFP_KERNEL); + if ((id && !clk->id) || !clk->dev_id) { + ret = -ENOMEM; + goto ealloc; + } + clk->ops = ops; + clk->priv = priv; + atomic_set(&clk->use_count, 0); + mutex_init(&clk->lock); + + mutex_lock(&clk_lock); + if (!IS_ERR(v4l2_clk_find(dev_id, id))) { + mutex_unlock(&clk_lock); + ret = -EEXIST; + goto eexist; + } + list_add_tail(&clk->list, &clk_list); + mutex_unlock(&clk_lock); + + return clk; + +eexist: +ealloc: + kfree(clk->id); + kfree(clk->dev_id); + kfree(clk); + return ERR_PTR(ret); +} +EXPORT_SYMBOL(v4l2_clk_register); + +void v4l2_clk_unregister(struct v4l2_clk *clk) +{ + if (WARN(atomic_read(&clk->use_count), + "%s(): Refusing to unregister ref-counted %s:%s clock!\n", + __func__, clk->dev_id, clk->id)) + return; + + mutex_lock(&clk_lock); + list_del(&clk->list); + mutex_unlock(&clk_lock); + + kfree(clk->id); + kfree(clk->dev_id); + kfree(clk); +} +EXPORT_SYMBOL(v4l2_clk_unregister); diff --git a/include/media/v4l2-clk.h b/include/media/v4l2-clk.h new file mode 100644 index 0000000..9b67472 --- /dev/null +++ b/include/media/v4l2-clk.h @@ -0,0 +1,54 @@ +/* + * V4L2 clock service + * + * Copyright (C) 2012, Guennadi Liakhovetski + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * ATTENTION: This is a temporary API and it shall be replaced by the generic + * clock API, when the latter becomes widely available. + */ + +#ifndef MEDIA_V4L2_CLK_H +#define MEDIA_V4L2_CLK_H + +#include +#include +#include + +struct module; +struct v4l2_subdev; + +struct v4l2_clk { + struct list_head list; + const struct v4l2_clk_ops *ops; + const char *dev_id; + const char *id; + int enable; + struct mutex lock; /* Protect the enable count */ + atomic_t use_count; + void *priv; +}; + +struct v4l2_clk_ops { + struct module *owner; + int (*enable)(struct v4l2_clk *clk); + void (*disable)(struct v4l2_clk *clk); + unsigned long (*get_rate)(struct v4l2_clk *clk); + int (*set_rate)(struct v4l2_clk *clk, unsigned long); +}; + +struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops, + const char *dev_name, + const char *name, void *priv); +void v4l2_clk_unregister(struct v4l2_clk *clk); +struct v4l2_clk *v4l2_clk_get(struct v4l2_subdev *sd, const char *id); +void v4l2_clk_put(struct v4l2_clk *clk); +int v4l2_clk_enable(struct v4l2_clk *clk); +void v4l2_clk_disable(struct v4l2_clk *clk); +unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk); +int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate); + +#endif