Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030408Ab2B1U1n (ORCPT ); Tue, 28 Feb 2012 15:27:43 -0500 Received: from hqemgate04.nvidia.com ([216.228.121.35]:8219 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964871Ab2B1U1j (ORCPT ); Tue, 28 Feb 2012 15:27:39 -0500 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Tue, 28 Feb 2012 12:27:37 -0800 From: Stephen Warren To: Linus Walleij CC: Linus Walleij , , , , , , , , Stephen Warren Subject: [PATCH V2 3/6] pinctrl: Add usecount to pins for muxing Date: Tue, 28 Feb 2012 13:27:29 -0700 Message-ID: <1330460852-23486-4-git-send-email-swarren@nvidia.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: <1330460852-23486-1-git-send-email-swarren@nvidia.com> References: <1330460852-23486-1-git-send-email-swarren@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3645 Lines: 109 Multiple mapping table entries could reference the same pin, and hence "own" it. This would be unusual now that pinctrl_get() represents a single state for a client device, but in the future when it represents all known states for a device, this is quite likely. Implement reference counting for pin ownership to handle this. Signed-off-by: Stephen Warren Acked-by: Dong Aisheng --- v2: Added kerneldoc for @usecount and @owner fields - the latter was missing from a previous patch. drivers/pinctrl/core.h | 12 +++++++++--- drivers/pinctrl/pinmux.c | 23 +++++++++++++++++++---- 2 files changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h index de8df86..0bc52ec 100644 --- a/drivers/pinctrl/core.h +++ b/drivers/pinctrl/core.h @@ -82,9 +82,14 @@ struct pinctrl_setting { * @name: a name for the pin, e.g. the name of the pin/pad/finger on a * datasheet or such * @dynamic_name: if the name of this pin was dynamically allocated - * @mux_requested: whether the pin is already requested by pinmux or not - * @mux_function: a named muxing function for the pin that will be passed to - * subdrivers and shown in debugfs etc + * @usecount: If zero, the pin is not claimed, and @owner should be NULL. + * If non-zero, this pin is claimed by @owner. This field is an integer + * rather than a boolean, since pinctrl_get() might process multiple + * mapping table entries that refer to, and hence claim, the same group + * or pin, and each of these will increment the @usecount. + * @owner: The name of the entity owning the pin. Typically, this is the name + * of the device that called pinctrl_get(). Alternatively, it may be the + * name of the GPIO passed to pinctrl_request_gpio(). */ struct pin_desc { struct pinctrl_dev *pctldev; @@ -92,6 +97,7 @@ struct pin_desc { bool dynamic_name; /* These fields only added when supporting pinmux drivers */ #ifdef CONFIG_PINMUX + unsigned usecount; const char *owner; #endif }; diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c index 2318d85..2d1aaf8 100644 --- a/drivers/pinctrl/pinmux.c +++ b/drivers/pinctrl/pinmux.c @@ -83,11 +83,16 @@ static int pin_request(struct pinctrl_dev *pctldev, goto out; } - if (desc->owner && strcmp(desc->owner, owner)) { + if (desc->usecount && strcmp(desc->owner, owner)) { dev_err(pctldev->dev, "pin already requested\n"); goto out; } + + desc->usecount++; + if (desc->usecount > 1) + return 0; + desc->owner = owner; /* Let each pin increase references to this module */ @@ -111,12 +116,18 @@ static int pin_request(struct pinctrl_dev *pctldev, else status = 0; - if (status) + if (status) { dev_err(pctldev->dev, "->request on device %s failed for pin %d\n", pctldev->desc->name, pin); + module_put(pctldev->owner); + } + out_free_pin: - if (status) - desc->owner = NULL; + if (status) { + desc->usecount--; + if (!desc->usecount) + desc->owner = NULL; + } out: if (status) dev_err(pctldev->dev, "pin-%d (%s) status %d\n", @@ -150,6 +161,10 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, return NULL; } + desc->usecount--; + if (desc->usecount) + return NULL; + /* * If there is no kind of request function for the pin we just assume * we got it by default and proceed. -- 1.7.0.4 -- 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/