From patchwork Thu Feb 27 06:05:14 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: yao yuan X-Patchwork-Id: 3730471 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 21BC1BF13A for ; Thu, 27 Feb 2014 07:12:01 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C5E76201FE for ; Thu, 27 Feb 2014 07:11:59 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 98B86201EF for ; Thu, 27 Feb 2014 07:11:57 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WIv8G-0004oW-TT; Thu, 27 Feb 2014 07:11:49 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WIv8E-0002vQ-FC; Thu, 27 Feb 2014 07:11:46 +0000 Received: from va3ehsobe004.messaging.microsoft.com ([216.32.180.14] helo=va3outboundpool.messaging.microsoft.com) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WIv7t-0002uL-66 for linux-arm-kernel@lists.infradead.org; Thu, 27 Feb 2014 07:11:31 +0000 Received: from mail182-va3-R.bigfish.com (10.7.14.241) by VA3EHSOBE011.bigfish.com (10.7.40.61) with Microsoft SMTP Server id 14.1.225.22; Thu, 27 Feb 2014 07:10:56 +0000 Received: from mail182-va3 (localhost [127.0.0.1]) by mail182-va3-R.bigfish.com (Postfix) with ESMTP id DD91436024F; Thu, 27 Feb 2014 07:10:55 +0000 (UTC) X-Forefront-Antispam-Report: CIP:70.37.183.190; KIP:(null); UIP:(null); IPV:NLI; H:mail.freescale.net; RD:none; EFVD:NLI X-SpamScore: 0 X-BigFish: VS0(zze0eahzz1f42h2148h208ch1ee6h1de0h1fdah2073h2146h1202h1e76h2189h1d1ah1d2ah21bch1fc6hzz1de098h8275bh1de097hz2dh2a8h839hd24he5bhf0ah1288h12a5h12a9h12bdh12e5h137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh2222h224fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h2218h2216h226dh22d0h24afh2327h2336h2438h2461h2487h24d7h2516h2545h255eh25cch1155h) Received: from mail182-va3 (localhost.localdomain [127.0.0.1]) by mail182-va3 (MessageSwitch) id 1393485053419727_2031; Thu, 27 Feb 2014 07:10:53 +0000 (UTC) Received: from VA3EHSMHS007.bigfish.com (unknown [10.7.14.250]) by mail182-va3.bigfish.com (Postfix) with ESMTP id 55027480045; Thu, 27 Feb 2014 07:10:53 +0000 (UTC) Received: from mail.freescale.net (70.37.183.190) by VA3EHSMHS007.bigfish.com (10.7.99.17) with Microsoft SMTP Server (TLS) id 14.16.227.3; Thu, 27 Feb 2014 07:10:52 +0000 Received: from az84smr01.freescale.net (10.64.34.197) by 039-SN1MMR1-002.039d.mgd.msft.net (10.84.1.15) with Microsoft SMTP Server (TLS) id 14.3.158.2; Thu, 27 Feb 2014 07:10:51 +0000 Received: from rock.am.freescale.net (rock.ap.freescale.net [10.193.20.106]) by az84smr01.freescale.net (8.14.3/8.14.0) with ESMTP id s1R7AgUn032092; Thu, 27 Feb 2014 00:10:48 -0700 From: Yuan Yao To: Subject: [PATCH 1/3] i2c: add DMA support for freescale i2c driver Date: Thu, 27 Feb 2014 14:05:14 +0800 Message-ID: <1393481115-22136-2-git-send-email-yao.yuan@freescale.com> X-Mailer: git-send-email 1.8.0 In-Reply-To: <1393481115-22136-1-git-send-email-yao.yuan@freescale.com> References: <1393481115-22136-1-git-send-email-yao.yuan@freescale.com> MIME-Version: 1.0 X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140227_021125_335937_13B38089 X-CRM114-Status: GOOD ( 21.39 ) X-Spam-Score: -2.6 (--) Cc: mark.rutland@arm.com, shawn.guo@linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add dma support for i2c. This function depend on DMA driver. You can turn on it by write both the dmas and dma-name properties in dts node. And you should set ".has_dma_support" as true for dma support in imx_i2c_hwdata struct. Signed-off-by: Yuan Yao --- drivers/i2c/busses/i2c-imx.c | 358 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 344 insertions(+), 14 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index db895fb..6ec392b 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -37,22 +37,27 @@ /** Includes ******************************************************************* *******************************************************************************/ -#include -#include -#include +#include +#include +#include +#include +#include +#include #include #include #include -#include #include +#include #include -#include -#include -#include -#include +#include +#include #include #include +#include #include +#include +#include +#include /** Defines ******************************************************************** *******************************************************************************/ @@ -63,6 +68,9 @@ /* Default value */ #define IMX_I2C_BIT_RATE 100000 /* 100kHz */ +/* enable DMA if transfer size is bigger than this threshold */ +#define IMX_I2C_DMA_THRESHOLD 16 + /* IMX I2C registers: * the I2C register offset is different between SoCs, * to provid support for all these chips, split the @@ -88,6 +96,7 @@ #define I2SR_IBB 0x20 #define I2SR_IAAS 0x40 #define I2SR_ICF 0x80 +#define I2CR_DMAEN 0x02 #define I2CR_RSTA 0x04 #define I2CR_TXAK 0x08 #define I2CR_MTX 0x10 @@ -172,6 +181,17 @@ struct imx_i2c_hwdata { unsigned ndivs; unsigned i2sr_clr_opcode; unsigned i2cr_ien_opcode; + bool has_dma_support; +}; + +struct imx_i2c_dma { + struct dma_chan *chan_tx; + struct dma_chan *chan_rx; + dma_addr_t buf_tx; + dma_addr_t buf_rx; + unsigned int len_tx; + unsigned int len_rx; + struct completion cmd_complete; }; struct imx_i2c_struct { @@ -184,6 +204,9 @@ struct imx_i2c_struct { int stopped; unsigned int ifdr; /* IMX_I2C_IFDR */ const struct imx_i2c_hwdata *hwdata; + + bool use_dma; + struct imx_i2c_dma *dma; }; static const struct imx_i2c_hwdata imx1_i2c_hwdata = { @@ -193,6 +216,7 @@ static const struct imx_i2c_hwdata imx1_i2c_hwdata = { .ndivs = ARRAY_SIZE(imx_i2c_clk_div), .i2sr_clr_opcode = I2SR_CLR_OPCODE_W0C, .i2cr_ien_opcode = I2CR_IEN_OPCODE_1, + .has_dma_support = false, }; @@ -203,6 +227,7 @@ static const struct imx_i2c_hwdata imx21_i2c_hwdata = { .ndivs = ARRAY_SIZE(imx_i2c_clk_div), .i2sr_clr_opcode = I2SR_CLR_OPCODE_W0C, .i2cr_ien_opcode = I2CR_IEN_OPCODE_1, + .has_dma_support = false, }; @@ -213,6 +238,7 @@ static struct imx_i2c_hwdata vf610_i2c_hwdata = { .ndivs = ARRAY_SIZE(vf610_i2c_clk_div), .i2sr_clr_opcode = I2SR_CLR_OPCODE_W1C, .i2cr_ien_opcode = I2CR_IEN_OPCODE_0, + .has_dma_support = true, }; @@ -254,6 +280,155 @@ static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx, return readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift)); } +/** Functions for DMA support ************************************************ +******************************************************************************/ +static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, u32 phy_addr) +{ + struct imx_i2c_dma *dma = i2c_imx->dma; + struct dma_slave_config dma_sconfig; + int ret; + + dma->chan_tx = dma_request_slave_channel(&i2c_imx->adapter.dev, "tx"); + if (!dma->chan_tx) { + dev_err(&i2c_imx->adapter.dev, + "Dma tx channel request failed!\n"); + return -ENODEV; + } + + dma_sconfig.dst_addr = (dma_addr_t)phy_addr + + (IMX_I2C_I2DR << i2c_imx->hwdata->regshift); + dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.dst_maxburst = 1; + dma_sconfig.direction = DMA_MEM_TO_DEV; + ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig); + if (ret < 0) { + dev_err(&i2c_imx->adapter.dev, + "Dma slave config failed, err = %d\n", ret); + dma_release_channel(dma->chan_tx); + return ret; + } + + dma->chan_rx = dma_request_slave_channel(&i2c_imx->adapter.dev, "rx"); + if (!dma->chan_rx) { + dev_err(&i2c_imx->adapter.dev, + "Dma rx channel request failed!\n"); + return -ENODEV; + } + + dma_sconfig.src_addr = (dma_addr_t)phy_addr + + (IMX_I2C_I2DR << i2c_imx->hwdata->regshift); + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.src_maxburst = 1; + dma_sconfig.direction = DMA_DEV_TO_MEM; + ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig); + if (ret < 0) { + dev_err(&i2c_imx->adapter.dev, + "Dma slave config failed, err = %d\n", ret); + dma_release_channel(dma->chan_rx); + return ret; + } + + init_completion(&dma->cmd_complete); + + return 0; +} + +static void i2c_imx_dma_tx_callback(void *arg) +{ + struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg; + struct imx_i2c_dma *dma = i2c_imx->dma; + + dma_unmap_single(dma->chan_tx->device->dev, dma->buf_tx, + dma->len_tx, DMA_TO_DEVICE); + complete(&dma->cmd_complete); +} + +static int i2c_imx_dma_tx(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) +{ + struct imx_i2c_dma *dma = i2c_imx->dma; + struct dma_async_tx_descriptor *txdesc; + + dma->len_tx = msgs->len-1; + dma->buf_tx = dma_map_single(dma->chan_tx->device->dev, msgs->buf, + dma->len_tx, DMA_TO_DEVICE); + if (dma_mapping_error(dma->chan_tx->device->dev, dma->buf_tx)) { + dev_err(&i2c_imx->adapter.dev, "dma_map_single tx failed\n"); + return -EINVAL; + } + + txdesc = dmaengine_prep_slave_single(dma->chan_tx, dma->buf_tx, + dma->len_tx, DMA_MEM_TO_DEV, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!txdesc) { + dev_err(&i2c_imx->adapter.dev, + "Not able to get desc for tx\n"); + return -EINVAL; + } + + txdesc->callback = i2c_imx_dma_tx_callback; + txdesc->callback_param = i2c_imx; + dmaengine_submit(txdesc); + dma_async_issue_pending(dma->chan_tx); + + return 0; +} + +static void i2c_imx_dma_rx_callback(void *arg) +{ + struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg; + struct imx_i2c_dma *dma = i2c_imx->dma; + + dma_unmap_single(dma->chan_rx->device->dev, dma->buf_rx, + dma->len_rx, DMA_FROM_DEVICE); + complete(&dma->cmd_complete); +} + +static int i2c_imx_dma_rx(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) +{ + struct imx_i2c_dma *dma = i2c_imx->dma; + struct dma_async_tx_descriptor *txdesc; + + dma->len_rx = msgs->len - 2; + dma->buf_rx = dma_map_single(dma->chan_rx->device->dev, msgs->buf, + dma->len_rx, DMA_FROM_DEVICE); + if (dma_mapping_error(dma->chan_rx->device->dev, dma->buf_rx)) { + dev_err(&i2c_imx->adapter.dev, "dma_map_single tx failed\n"); + return -EINVAL; + } + + txdesc = dmaengine_prep_slave_single(dma->chan_rx, dma->buf_rx, + dma->len_rx, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!txdesc) { + dev_err(&i2c_imx->adapter.dev, + "Not able to get desc for rx\n"); + return -EINVAL; + } + + txdesc->callback = i2c_imx_dma_rx_callback; + txdesc->callback_param = i2c_imx; + dmaengine_submit(txdesc); + dma_async_issue_pending(dma->chan_rx); + + return 0; +} +static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) +{ + struct imx_i2c_dma *dma = i2c_imx->dma; + struct dma_chan *dma_chan; + + dma_chan = dma->chan_tx; + dma->chan_tx = NULL; + dma->buf_tx = 0; + dma->len_tx = 0; + dma_release_channel(dma_chan); + + dma_chan = dma->chan_rx; + dma->chan_tx = NULL; + dma->buf_rx = 0; + dma->len_rx = 0; + dma_release_channel(dma_chan); +} /** Functions for IMX I2C adapter driver *************************************** *******************************************************************************/ @@ -425,7 +600,8 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) return IRQ_NONE; } -static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) +static int i2c_imx_pio_write(struct imx_i2c_struct *i2c_imx, + struct i2c_msg *msgs) { int i, result; @@ -458,7 +634,56 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) return 0; } -static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) +static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx, + struct i2c_msg *msgs) +{ + int result, timeout=1000; + unsigned int temp = 0; + + reinit_completion(&i2c_imx->dma->cmd_complete); + result = i2c_imx_dma_tx(i2c_imx, msgs); + if(result) + return result; + + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_DMAEN; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + + /* write slave address */ + imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR); + result = wait_for_completion_interruptible_timeout( + &i2c_imx->dma->cmd_complete, + msecs_to_jiffies(1000)); + if (result == 0) + return -ETIMEDOUT; + + /* waiting for Transfer complete. */ + while(timeout--) { + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR); + if (temp & 0x80) + break; + udelay(10); + } + + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp &= ~I2CR_DMAEN; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + + /* write the last byte */ + imx_i2c_write_reg(msgs->buf[msgs->len-1], i2c_imx, IMX_I2C_I2DR); + result = i2c_imx_trx_complete(i2c_imx); + if (result) + return result; + + result = i2c_imx_acked(i2c_imx); + if (result) + return result; + + return 0; +} + +static int i2c_imx_pio_read(struct imx_i2c_struct *i2c_imx, + struct i2c_msg *msgs) { int i, result; unsigned int temp; @@ -518,6 +743,80 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs) return 0; } +static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, + struct i2c_msg *msgs) +{ + int result, timeout=1000; + unsigned int temp; + + /* write slave address */ + imx_i2c_write_reg((msgs->addr << 1) | 0x01, i2c_imx, IMX_I2C_I2DR); + result = i2c_imx_trx_complete(i2c_imx); + if (result) + return result; + + result = i2c_imx_acked(i2c_imx); + if (result) + return result; + + /* setup bus to read data */ + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp &= ~I2CR_MTX; + if (msgs->len - 1) + temp &= ~I2CR_TXAK; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */ + + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_DMAEN; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + + reinit_completion(&i2c_imx->dma->cmd_complete); + result = i2c_imx_dma_rx(i2c_imx, msgs); + if(result) + return result; + + result = wait_for_completion_interruptible_timeout( + &i2c_imx->dma->cmd_complete, + msecs_to_jiffies(1000)); + if (result == 0) + return -ETIMEDOUT; + + /* waiting for Transfer complete. */ + while(timeout--) { + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR); + if (temp & 0x80) + break; + udelay(10); + } + + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp &= ~I2CR_DMAEN; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + + /* read n-1 byte data */ + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_TXAK; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + + msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); + /* read n byte data */ + result = i2c_imx_trx_complete(i2c_imx); + if (result) + return result; + + /* It must generate STOP before read I2DR to prevent + controller from generating another clock cycle */ + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp &= ~(I2CR_MSTA | I2CR_MTX); + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + i2c_imx_bus_busy(i2c_imx, 0); + i2c_imx->stopped = 1; + msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); + + return 0; +} + static int i2c_imx_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) { @@ -563,10 +862,18 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, (temp & I2SR_SRW ? 1 : 0), (temp & I2SR_IIF ? 1 : 0), (temp & I2SR_RXAK ? 1 : 0)); #endif - if (msgs[i].flags & I2C_M_RD) - result = i2c_imx_read(i2c_imx, &msgs[i]); - else - result = i2c_imx_write(i2c_imx, &msgs[i]); + if(i2c_imx->use_dma && msgs[i].len >= IMX_I2C_DMA_THRESHOLD) { + if (msgs[i].flags & I2C_M_RD) + result = i2c_imx_dma_read(i2c_imx, &msgs[i]); + else + result = i2c_imx_dma_write(i2c_imx, &msgs[i]); + } else { + if (msgs[i].flags & I2C_M_RD) + result = i2c_imx_pio_read(i2c_imx, &msgs[i]); + else + result = i2c_imx_pio_write(i2c_imx, &msgs[i]); + } + if (result) goto fail0; } @@ -601,6 +908,7 @@ static int i2c_imx_probe(struct platform_device *pdev) void __iomem *base; int irq, ret; u32 bitrate; + u32 phy_addr; dev_dbg(&pdev->dev, "<%s>\n", __func__); @@ -611,6 +919,7 @@ static int i2c_imx_probe(struct platform_device *pdev) } res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + phy_addr = res->start; base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(base)) return PTR_ERR(base); @@ -696,6 +1005,24 @@ static int i2c_imx_probe(struct platform_device *pdev) i2c_imx->adapter.name); dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n"); + /* Init DMA config if support*/ + if (i2c_imx->hwdata->has_dma_support) { + dev_info(&pdev->dev, "has_dma_support_begin.\n"); + i2c_imx->dma = devm_kzalloc(&pdev->dev, sizeof(struct imx_i2c_dma), + GFP_KERNEL); + if (!i2c_imx->dma) { + dev_info(&pdev->dev, "can't allocate dma struct faild use dma.\n"); + i2c_imx->use_dma = false; + } + else if (i2c_imx_dma_request(i2c_imx, phy_addr)) { + dev_info(&pdev->dev, "can't request dma chan, faild use dma.\n"); + i2c_imx->use_dma = false; + } + else { + i2c_imx->use_dma = true; + } + } + return 0; /* Return OK */ } @@ -707,6 +1034,9 @@ static int i2c_imx_remove(struct platform_device *pdev) dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n"); i2c_del_adapter(&i2c_imx->adapter); + if (i2c_imx->use_dma) + i2c_imx_dma_free(i2c_imx); + /* setup chip registers to defaults */ imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR); imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);