From patchwork Tue Jun 11 08:23:41 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guennadi Liakhovetski X-Patchwork-Id: 2701051 Return-Path: X-Original-To: patchwork-linux-media@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 9C4C6DF23A for ; Tue, 11 Jun 2013 10:00:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753824Ab3FKKAG (ORCPT ); Tue, 11 Jun 2013 06:00:06 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:55489 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752168Ab3FKKAF (ORCPT ); Tue, 11 Jun 2013 06:00:05 -0400 Received: from axis700.grange (dslb-178-001-148-081.pools.arcor-ip.net [178.1.148.81]) by mrelayeu.kundenserver.de (node=mreu3) with ESMTP (Nemesis) id 0LmAhq-1UCS8s2SLC-00Zux4; Tue, 11 Jun 2013 11:29:37 +0200 Received: from 6a.grange (unknown [192.168.1.11]) by axis700.grange (Postfix) with ESMTPS id 3EB8C40BCC; Tue, 11 Jun 2013 10:24:05 +0200 (CEST) Received: from lyakh by 6a.grange with local (Exim 4.72) (envelope-from ) id 1UmJs4-0002Bp-Rx; Tue, 11 Jun 2013 10:24:04 +0200 From: Guennadi Liakhovetski To: linux-media@vger.kernel.org Cc: Laurent Pinchart , Sylwester Nawrocki , Hans Verkuil , linux-sh@vger.kernel.org, Magnus Damm , Sakari Ailus , Prabhakar Lad , Sascha Hauer , Guennadi Liakhovetski Subject: [PATCH v10 14/21] V4L2: add temporary clock helpers Date: Tue, 11 Jun 2013 10:23:41 +0200 Message-Id: <1370939028-8352-15-git-send-email-g.liakhovetski@gmx.de> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1370939028-8352-1-git-send-email-g.liakhovetski@gmx.de> References: <1370939028-8352-1-git-send-email-g.liakhovetski@gmx.de> X-Provags-ID: V02:K0:kceQvDZ3AWLN98ljaPr+nSBQ8uL6TiNgyhJMR46E9lM b62q96S7fBgAkqh01ODxLKYO2OYDqaeruxtgSn2LjRNzkcWJ5B SHEo2cdJ9u1TcAIQIuDTRy/C7mnQkZBbBzYxfR4J6XzSbLC26S CLNgGGpitcvqGjRB1XITwjislpoYs7mIKWSSV4llKTKs2GNUy5 9SRaK6vrCmpCV9TZ1XRZ1OQvs4CZKo6D53C3oMUBdMI5N4HGeo i9GtELDgTQARlDPZcO73odKQvYQYEaK7G0IHqcI4uGfFipGPS5 8BRm6BjJXjDyDVGehpMIB7Rp8qFfSQPXeedHZo8/Nz7Qx8hiVy yaY5WsA6NJ0K2gV3bIdDkmUCQFUKDVKJ3m70jhi4nx33b6eXC/ HzNcJr++rpkcQ== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@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 --- v10: lock the driver only between enable / disable to avoid a circular dependency and allow driver unloading. drivers/media/v4l2-core/Makefile | 2 +- drivers/media/v4l2-core/v4l2-clk.c | 242 ++++++++++++++++++++++++++++++++++++ include/media/v4l2-clk.h | 54 ++++++++ 3 files changed, 297 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 aa50c46..628c630 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..b67de86 --- /dev/null +++ b/drivers/media/v4l2-core/v4l2-clk.c @@ -0,0 +1,242 @@ +/* + * V4L2 clock service + * + * Copyright (C) 2012-2013, 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 + +#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 device *dev, const char *id) +{ + struct v4l2_clk *clk; + + mutex_lock(&clk_lock); + clk = v4l2_clk_find(dev_name(dev), id); + + if (!IS_ERR(clk)) + atomic_inc(&clk->use_count); + mutex_unlock(&clk_lock); + + return clk; +} +EXPORT_SYMBOL(v4l2_clk_get); + +void v4l2_clk_put(struct v4l2_clk *clk) +{ + struct v4l2_clk *tmp; + + if (IS_ERR(clk)) + return; + + mutex_lock(&clk_lock); + + list_for_each_entry(tmp, &clk_list, list) + if (tmp == clk) + atomic_dec(&clk->use_count); + + mutex_unlock(&clk_lock); +} +EXPORT_SYMBOL(v4l2_clk_put); + +static int v4l2_clk_lock_driver(struct v4l2_clk *clk) +{ + struct v4l2_clk *tmp; + int ret = -ENODEV; + + mutex_lock(&clk_lock); + + list_for_each_entry(tmp, &clk_list, list) + if (tmp == clk) { + ret = !try_module_get(clk->ops->owner); + if (ret) + ret = -EFAULT; + break; + } + + mutex_unlock(&clk_lock); + + return ret; +} + +static void v4l2_clk_unlock_driver(struct v4l2_clk *clk) +{ + module_put(clk->ops->owner); +} + +int v4l2_clk_enable(struct v4l2_clk *clk) +{ + int ret = v4l2_clk_lock_driver(clk); + + if (ret < 0) + return ret; + + mutex_lock(&clk->lock); + + if (++clk->enable == 1 && clk->ops->enable) { + ret = clk->ops->enable(clk); + if (ret < 0) + clk->enable--; + } + + mutex_unlock(&clk->lock); + + return ret; +} +EXPORT_SYMBOL(v4l2_clk_enable); + +/* + * You might Oops if you try to disabled a disabled clock, because then the + * driver isn't locked and could have been unloaded by now, so, don't do that + */ +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); + + v4l2_clk_unlock_driver(clk); +} +EXPORT_SYMBOL(v4l2_clk_disable); + +unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk) +{ + int ret = v4l2_clk_lock_driver(clk); + + if (ret < 0) + return ret; + + mutex_lock(&clk->lock); + if (!clk->ops->get_rate) + ret = -ENOSYS; + else + ret = clk->ops->get_rate(clk); + mutex_unlock(&clk->lock); + + v4l2_clk_unlock_driver(clk); + + return ret; +} +EXPORT_SYMBOL(v4l2_clk_get_rate); + +int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate) +{ + int ret = v4l2_clk_lock_driver(clk); + + if (ret < 0) + return ret; + + mutex_lock(&clk->lock); + if (!clk->ops->set_rate) + ret = -ENOSYS; + else + ret = clk->ops->set_rate(clk, rate); + mutex_unlock(&clk->lock); + + v4l2_clk_unlock_driver(clk); + + return ret; +} +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..0503a90 --- /dev/null +++ b/include/media/v4l2-clk.h @@ -0,0 +1,54 @@ +/* + * V4L2 clock service + * + * Copyright (C) 2012-2013, 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 device; + +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 device *dev, 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