From patchwork Sat Feb 16 02:38:41 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Torokhov X-Patchwork-Id: 220914 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id DF01B2C007A for ; Sat, 16 Feb 2013 13:39:03 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752378Ab3BPCip (ORCPT ); Fri, 15 Feb 2013 21:38:45 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:49619 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752242Ab3BPCin (ORCPT ); Fri, 15 Feb 2013 21:38:43 -0500 Received: by mail-pb0-f46.google.com with SMTP id uo15so843112pbc.19 for ; Fri, 15 Feb 2013 18:38:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:date:from:to:cc:subject:message-id:mime-version :content-type:content-disposition:user-agent; bh=J931v6wxjrwaqsd9pUV8THcT+AQGt0VHbV+cubPGXCo=; b=gSIXZoPFt8suEFhqWd3I8CdyCRJkbiidn1lt23hbOiIHPVUIBquiPqQyNBQ8lLZn46 /Yk5475/76tZIZaydE/8cNXg8OE365flo/Md1r4iMJSuVJI33tdkXWDOIvZkGTXoZkXL +JjbM5Y/zcQQ+3Gz64xFNL8BHQ5aiJVA1V0+4S2TlsVCj8fcWkLBq5Q3YuKcNvjaT83w rDq4osxbWSTPkE789dcFXCMS43YRPHxMT6pxZS8pt/XfzvBsTMV5tyQ4Sm1ceuHe5Pga cl6YaTsCzytlzZ1OYh/BfWa2GisSs2eiAUfYaoPTcPYgrSMf50/jiywPpH/8SWD2o3vB 5Y+g== X-Received: by 10.68.195.33 with SMTP id ib1mr10784779pbc.105.1360982323339; Fri, 15 Feb 2013 18:38:43 -0800 (PST) Received: from mailhub.coreip.homeip.net (c-67-188-112-76.hsd1.ca.comcast.net. [67.188.112.76]) by mx.google.com with ESMTPS id is7sm6489583pbc.15.2013.02.15.18.38.42 (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 15 Feb 2013 18:38:42 -0800 (PST) Date: Fri, 15 Feb 2013 18:38:41 -0800 From: Dmitry Torokhov To: Wolfram Sang Cc: Ben Dooks , Jean Delvare , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] I2C: add i2c_master_send_exact() and friends Message-ID: <20130216023840.GA16084@core.coreip.homeip.net> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Many i2c users consider short transfers to be an error and would prefer getting -EIO instead of a positive return value and having to convert it to error code by themselves. So let's add the following new helpers: i2c_master_send_exact() i2c_master_recv_exact() i2c_transfer_exact() Signed-off-by: Dmitry Torokhov --- drivers/i2c/i2c-core.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 11 ++++++++ 2 files changed, 80 insertions(+) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index e388590..6cddb5d 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1430,6 +1430,33 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) EXPORT_SYMBOL(i2c_transfer); /** + * i2c_transfer_exact - transfer given number of I2C messages + * @adap: Handle to I2C bus + * @msgs: One or more messages to execute before STOP is issued to + * terminate the operation; each message begins with a START. + * @num: Number of messages to be executed. + * + * Returns negative errno (including -EIO on short transfer), + * or 0 if all messages have been tranferred successfully. + * + * Note that there is no requirement that each message be sent to + * the same slave address, although that is the most common model. + */ +int i2c_transfer_exact(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + int ret; + + ret = i2c_transfer(adap, msgs, num); + if (ret == num) + return 0; + + return ret < 0 ? ret : -EIO; + +} +EXPORT_SYMBOL(i2c_transfer_exact); + +/** * i2c_master_send - issue a single I2C message in master transmit mode * @client: Handle to slave device * @buf: Data that will be written to the slave @@ -1459,6 +1486,27 @@ int i2c_master_send(const struct i2c_client *client, const char *buf, int count) EXPORT_SYMBOL(i2c_master_send); /** + * i2c_master_send_exact - send exact number of bytes in master transmit mode + * @client: Handle to slave device + * @buf: Data that will be written to the slave + * @count: How many bytes to write, must be less than 64k since msg.len is u16 + * + * Returns negative errno (including -EIO on short transfer), or 0. + */ +int i2c_master_send_exact(const struct i2c_client *client, + const char *buf, int count) +{ + int ret; + + ret = i2c_master_send(client, buf, count); + if (ret == count) + return 0; + + return ret < 0 ? ret : -EIO; +} +EXPORT_SYMBOL(i2c_master_send_exact); + +/** * i2c_master_recv - issue a single I2C message in master receive mode * @client: Handle to slave device * @buf: Where to store data read from slave @@ -1488,6 +1536,27 @@ int i2c_master_recv(const struct i2c_client *client, char *buf, int count) } EXPORT_SYMBOL(i2c_master_recv); +/** + * i2c_master_recv_exact - read exact number of bytes in master receive mode + * @client: Handle to slave device + * @buf: Where to store data read from slave + * @count: How many bytes to read, must be less than 64k since msg.len is u16 + * + * Returns negative errno (including -EIO on short transfer), or 0. + */ +int i2c_master_recv_exact(const struct i2c_client *client, + char *buf, int count) +{ + int ret; + + ret = i2c_master_recv(client, buf, count); + if (ret == count) + return 0; + + return ret < 0 ? ret : -EIO; +} +EXPORT_SYMBOL(i2c_master_recv_exact); + /* ---------------------------------------------------- * the i2c address scanning function * Will not work for 10-bit addresses! diff --git a/include/linux/i2c.h b/include/linux/i2c.h index d0c4db7..3d76059 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -59,13 +59,24 @@ struct module; */ extern int i2c_master_send(const struct i2c_client *client, const char *buf, int count); + +extern int i2c_master_send_exact(const struct i2c_client *client, + const char *buf, int count); + extern int i2c_master_recv(const struct i2c_client *client, char *buf, int count); +extern int i2c_master_recv_exact(const struct i2c_client *client, + char *buf, int count); + /* Transfer num messages. */ extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num); + +extern int i2c_transfer_exact(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num); + /* Unlocked flavor */ extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);