From patchwork Tue Jul 18 10:23:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 42612 Received: from mail.tu-berlin.de ([130.149.7.33]) by www.linuxtv.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dXPgp-0005PV-K0; Tue, 18 Jul 2017 10:25:15 +0000 X-tubIT-Incoming-IP: 209.132.180.67 Received: from vger.kernel.org ([209.132.180.67]) by mail.tu-berlin.de (exim-4.89/mailfrontend-8) with esmtp id 1dXPgn-0003l8-lV; Tue, 18 Jul 2017 12:25:15 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751505AbdGRKYT (ORCPT + 1 other); Tue, 18 Jul 2017 06:24:19 -0400 Received: from sauhun.de ([88.99.104.3]:36512 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751357AbdGRKYS (ORCPT ); Tue, 18 Jul 2017 06:24:18 -0400 Received: from localhost (p54B33852.dip0.t-ipconnect.de [84.179.56.82]) by pokefinder.org (Postfix) with ESMTPSA id D15F52C34F2; Tue, 18 Jul 2017 12:24:15 +0200 (CEST) From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-input@vger.kernel.org, linux-iio@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Wolfram Sang Subject: [PATCH v3 1/4] i2c: add helpers to ease DMA handling Date: Tue, 18 Jul 2017 12:23:36 +0200 Message-Id: <20170718102339.28726-2-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170718102339.28726-1-wsa+renesas@sang-engineering.com> References: <20170718102339.28726-1-wsa+renesas@sang-engineering.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-PMX-Version: 6.0.0.2142326, Antispam-Engine: 2.7.2.2107409, Antispam-Data: 2017.7.18.102116 X-PMX-Spam: Gauge=IIIIIIIII, Probability=9%, Report=' AT_TLD 0.1, MULTIPLE_RCPTS 0.1, HTML_00_01 0.05, HTML_00_10 0.05, BODY_SIZE_4000_4999 0, BODY_SIZE_5000_LESS 0, BODY_SIZE_7000_LESS 0, IN_REP_TO 0, LEGITIMATE_SIGNS 0, MSG_THREAD 0, MULTIPLE_REAL_RCPTS 0, NO_URI_HTTPS 0, REFERENCES 0, __ANY_URI 0, __CC_NAME 0, __CC_NAME_DIFF_FROM_ACC 0, __CC_REAL_NAMES 0, __FROM_DOMAIN_IN_ANY_CC2 0, __FROM_DOMAIN_IN_RCPT 0, __HAS_CC_HDR 0, __HAS_FROM 0, __HAS_LIST_ID 0, __HAS_MSGID 0, __HAS_X_MAILER 0, __HAS_X_MAILING_LIST 0, __IN_REP_TO 0, __MIME_TEXT_ONLY 0, __MIME_TEXT_P 0, __MIME_TEXT_P1 0, __MULTIPLE_RCPTS_CC_X2 0, __NO_HTML_TAG_RAW 0, __REFERENCES 0, __SANE_MSGID 0, __STOCK_PHRASE_7 0, __SUBJ_ALPHA_END 0, __TO_MALFORMED_2 0, __TO_NO_NAME 0, __URI_NO_WWW 0, __URI_NS ' One helper checks if DMA is suitable and optionally creates a bounce buffer, if not. The other function returns the bounce buffer and makes sure the data is properly copied back to the message. Signed-off-by: Wolfram Sang Reviewed-by: Niklas Söderlund --- Changes since v2: * rebased to v4.13-rc1 * helper functions are not inlined anymore but moved to i2c core * __must_check has been added to the buffer check helper * the release function has been renamed to contain 'dma' as well drivers/i2c/i2c-core-base.c | 68 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 5 ++++ 2 files changed, 73 insertions(+) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index c89dac7fd2e7b7..7326a9d2e4eb69 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include #include @@ -44,6 +45,7 @@ #include #include #include +#include #include #include "i2c-core.h" @@ -2240,6 +2242,72 @@ void i2c_put_adapter(struct i2c_adapter *adap) } EXPORT_SYMBOL(i2c_put_adapter); +/** + * i2c_check_msg_for_dma() - check if a message is suitable for DMA + * @msg: the message to be checked + * @threshold: the amount of byte from which using DMA makes sense + * @ptr_for_bounce_buf: if not NULL, a bounce buffer will be attached to this + * ptr, if needed. The bounce buffer must be freed by the + * caller using i2c_release_dma_bounce_buf(). + * + * Return: -ERANGE if message is smaller than threshold + * -EFAULT if message buffer is not DMA capable and no bounce buffer + * was requested + * -ENOMEM if a bounce buffer could not be created + * 0 if message is suitable for DMA + * + * The return value must be checked. + * + * Note: This function should only be called from process context! It uses + * helper functions which work on the 'current' task. + */ +int i2c_check_msg_for_dma(struct i2c_msg *msg, unsigned int threshold, + u8 **ptr_for_bounce_buf) +{ + if (ptr_for_bounce_buf) + *ptr_for_bounce_buf = NULL; + + if (msg->len < threshold) + return -ERANGE; + + if (!virt_addr_valid(msg->buf) || object_is_on_stack(msg->buf)) { + pr_debug("msg buffer to 0x%04x is not DMA safe%s\n", msg->addr, + ptr_for_bounce_buf ? ", trying bounce buffer" : ""); + if (ptr_for_bounce_buf) { + if (msg->flags & I2C_M_RD) + *ptr_for_bounce_buf = kzalloc(msg->len, GFP_KERNEL); + else + *ptr_for_bounce_buf = kmemdup(msg->buf, msg->len, + GFP_KERNEL); + if (!*ptr_for_bounce_buf) + return -ENOMEM; + } else { + return -EFAULT; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(i2c_check_msg_for_dma); + +/** + * i2c_release_bounce_buf - copy data back from bounce buffer and release it + * @msg: the message to be copied back to + * @bounce_buf: the bounce buffer obtained from i2c_check_msg_for_dma(). + * May be NULL. + */ +void i2c_release_dma_bounce_buf(struct i2c_msg *msg, u8 *bounce_buf) +{ + if (!bounce_buf) + return; + + if (msg->flags & I2C_M_RD) + memcpy(msg->buf, bounce_buf, msg->len); + + kfree(bounce_buf); +} +EXPORT_SYMBOL_GPL(i2c_release_bounce_buf); + MODULE_AUTHOR("Simon G. Vogl "); MODULE_DESCRIPTION("I2C-Bus main module"); MODULE_LICENSE("GPL"); diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 00ca5b86a753f8..ac02287b6c0d8f 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -766,6 +766,11 @@ static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg) return (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0); } +int __must_check i2c_check_msg_for_dma(struct i2c_msg *msg, unsigned int threshold, + u8 **ptr_for_bounce_buf); + +void i2c_release_dma_bounce_buf(struct i2c_msg *msg, u8 *bounce_buf); + int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr); /** * module_i2c_driver() - Helper macro for registering a modular I2C driver