Patchwork [3/4] MXS: Implement DMA support into mxs-i2c

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Submitter Marek Vasut
Date May 1, 2012, 2 a.m.
Message ID <1335837621-14816-4-git-send-email-marex@denx.de>
Download mbox | patch
Permalink /patch/156001/
State New
Headers show

Comments

Marek Vasut - May 1, 2012, 2 a.m.
This patch implements DMA support into mxs-i2c. DMA transfers are now enabled
via platform data. The behaviour of this driver should not change for any of
the current platforms. Though it is recommended to enable DMA operation.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
CC: Dong Aisheng <b29396@freescale.com>
CC: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Linux ARM kernel <linux-arm-kernel@lists.infradead.org>
Cc: linux-i2c@vger.kernel.org
CC: Sascha Hauer <s.hauer@pengutronix.de>
CC: Shawn Guo <shawn.guo@linaro.org>
Cc: Stefano Babic <sbabic@denx.de>
CC: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Wolfram Sang <w.sang@pengutronix.de>
---
 arch/arm/mach-mxs/devices/platform-mxs-i2c.c    |    5 +
 arch/arm/mach-mxs/include/mach/devices-common.h |    1 +
 drivers/i2c/busses/i2c-mxs.c                    |  260 +++++++++++++++++++++--
 include/linux/i2c/mxs-i2c.h                     |    1 +
 4 files changed, 244 insertions(+), 23 deletions(-)

Patch

diff --git a/arch/arm/mach-mxs/devices/platform-mxs-i2c.c b/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
index bb325b9..341aec9 100644
--- a/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
+++ b/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
@@ -15,6 +15,7 @@ 
 	{								\
 		.id = _id,						\
 		.iobase = soc ## _I2C ## _id ## _BASE_ADDR,		\
+		.dma	= soc ## _DMA_I2C ## _id,			\
 		.errirq = soc ## _INT_I2C ## _id ## _ERROR,		\
 		.dmairq = soc ## _INT_I2C ## _id ## _DMA,		\
 	}
@@ -39,6 +40,10 @@  struct platform_device *__init mxs_add_mxs_i2c(
 			.end = data->iobase + SZ_8K - 1,
 			.flags = IORESOURCE_MEM,
 		}, {
+			.start	= data->dma,
+			.end	= data->dma,
+			.flags	= IORESOURCE_DMA,
+		}, {
 			.start = data->errirq,
 			.end = data->errirq,
 			.flags = IORESOURCE_IRQ,
diff --git a/arch/arm/mach-mxs/include/mach/devices-common.h b/arch/arm/mach-mxs/include/mach/devices-common.h
index 7bf2894..f5d3bf6 100644
--- a/arch/arm/mach-mxs/include/mach/devices-common.h
+++ b/arch/arm/mach-mxs/include/mach/devices-common.h
@@ -81,6 +81,7 @@  mxs_add_gpmi_nand(const struct gpmi_nand_platform_data *pdata,
 struct mxs_mxs_i2c_data {
 	int id;
 	resource_size_t iobase;
+	resource_size_t dma;
 	resource_size_t errirq;
 	resource_size_t dmairq;
 };
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index 717b7f9..7491194 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -7,8 +7,6 @@ 
  *
  * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
  *
- * TODO: add dma-support if platform-support for it is available
- *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -27,6 +25,9 @@ 
 #include <linux/platform_device.h>
 #include <linux/jiffies.h>
 #include <linux/io.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/fsl/mxs-dma.h>
 
 #include <mach/common.h>
 
@@ -134,6 +135,16 @@  struct mxs_i2c_dev {
 	u32 cmd_err;
 	struct i2c_adapter adapter;
 	const struct mxs_i2c_speed_config *speed;
+
+	/* DMA support components */
+	bool				dma_mode;
+	struct resource			*dmares;
+	struct dma_chan         	*dmach;
+	struct mxs_dma_data		dma_data;
+	uint32_t			pio_data[2];
+	uint32_t			addr_data;
+	struct scatterlist		sg_io[2];
+	bool				dma_read;
 };
 
 /*
@@ -149,7 +160,12 @@  static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
 	writel(i2c->speed->timing2, i2c->regs + MXS_I2C_TIMING2);
 
 	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
-	writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
+
+	if (i2c->dma_mode)
+		writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
+			i2c->regs + MXS_I2C_QUEUECTRL_CLR);
+	else
+		writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
 			i2c->regs + MXS_I2C_QUEUECTRL_SET);
 }
 
@@ -240,9 +256,155 @@  static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
 	return 0;
 }
 
+static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
+{
+	if (i2c->dma_read) {
+		dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+		dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+	} else {
+		dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+	}
+}
+
+static void mxs_i2c_dma_irq_callback(void *param)
+{
+	struct mxs_i2c_dev *i2c = param;
+
+	complete(&i2c->cmd_complete);
+	mxs_i2c_dma_finish(i2c);
+}
+
+static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
+			struct i2c_msg *msg, uint32_t flags)
+{
+	struct dma_async_tx_descriptor *desc;
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+
+	if (msg->flags & I2C_M_RD) {
+		i2c->dma_read = 1;
+		i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_READ;
+
+		/*
+		 * SELECT command.
+		 */
+
+		/* Queue the PIO register write transfer. */
+		i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
+		desc = dmaengine_prep_slave_sg(i2c->dmach,
+					(struct scatterlist *)&i2c->pio_data[0],
+					1, DMA_TRANS_NONE, 0);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get PIO reg. write descriptor.\n");
+			goto select_init_pio_fail;
+		}
+
+		/* Queue the DMA data transfer. */
+		sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
+		dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+		desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
+					DMA_MEM_TO_DEV,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get DMA data write descriptor.\n");
+			goto select_init_dma_fail;
+		}
+
+		/*
+		 * READ command.
+		 */
+
+		/* Queue the PIO register write transfer. */
+		i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
+				MXS_I2C_CTRL0_XFER_COUNT(msg->len);
+		desc = dmaengine_prep_slave_sg(i2c->dmach,
+					(struct scatterlist *)&i2c->pio_data[1],
+					1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get PIO reg. write descriptor.\n");
+			goto select_init_dma_fail;
+		}
+
+		/* Queue the DMA data transfer. */
+		sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
+		dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+		desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
+					DMA_DEV_TO_MEM,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get DMA data write descriptor.\n");
+			goto read_init_dma_fail;
+		}
+	} else {
+		i2c->dma_read = 0;
+		i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_WRITE;
+
+		/*
+		 * WRITE command.
+		 */
+
+		/* Queue the PIO register write transfer. */
+		i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
+				MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
+		desc = dmaengine_prep_slave_sg(i2c->dmach,
+					(struct scatterlist *)&i2c->pio_data[0],
+					1, DMA_TRANS_NONE, 0);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get PIO reg. write descriptor.\n");
+			goto write_init_pio_fail;
+		}
+
+		/* Queue the DMA data transfer. */
+		sg_init_table(i2c->sg_io, 2);
+		sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
+		sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
+		dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+		desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
+					DMA_MEM_TO_DEV,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get DMA data write descriptor.\n");
+			goto write_init_dma_fail;
+		}
+	}
+
+	/*
+	 * The last descriptor must have this callback,
+	 * to finish the DMA transaction.
+	 */
+	desc->callback = mxs_i2c_dma_irq_callback;
+	desc->callback_param = i2c;
+
+	/* Start the transfer. */
+	dmaengine_submit(desc);
+	dma_async_issue_pending(i2c->dmach);
+	return 0;
+
+/* Read failpath. */
+read_init_dma_fail:
+	dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+select_init_dma_fail:
+	dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+select_init_pio_fail:
+	return 1;
+
+
+/* Write failpath. */
+write_init_dma_fail:
+	dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+write_init_pio_fail:
+	return 1;
+}
+
 /*
  * Low level master read/write transaction.
  */
+
 static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 				int stop)
 {
@@ -250,6 +412,8 @@  static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 	int ret;
 	int flags;
 
+	flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
+
 	dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 		msg->addr, msg->len, msg->flags, stop);
 
@@ -258,23 +422,30 @@  static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 
 	init_completion(&i2c->cmd_complete);
 
-	flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
-
-	if (msg->flags & I2C_M_RD)
-		mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
-	else
-		mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
-					flags);
+	if (i2c->dma_mode) {
+		ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
+		if (ret)
+			return -EINVAL;
+	} else {
+		if (msg->flags & I2C_M_RD) {
+			mxs_i2c_pioq_setup_read(i2c, msg->addr,
+						msg->len, flags);
+		} else {
+			mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf,
+						msg->len, flags);
+		}
 
-	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
+		writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
 			i2c->regs + MXS_I2C_QUEUECTRL_SET);
+	}
 
 	ret = wait_for_completion_timeout(&i2c->cmd_complete,
 						msecs_to_jiffies(1000));
+
 	if (ret == 0)
 		goto timeout;
 
-	if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
+	if (!i2c->dma_mode && (!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
 		ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
 		if (ret)
 			goto timeout;
@@ -289,7 +460,9 @@  static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 
 timeout:
 	dev_dbg(i2c->dev, "Timeout!\n");
+	mxs_i2c_dma_finish(i2c);
 	mxs_i2c_reset(i2c);
+
 	return -ETIMEDOUT;
 }
 
@@ -332,11 +505,13 @@  static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
 	else
 		i2c->cmd_err = 0;
 
-	is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
-		MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
+	if (!i2c->dma_mode) {
+		is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
+			MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
 
-	if (is_last_cmd || i2c->cmd_err)
-		complete(&i2c->cmd_complete);
+		if (!i2c->dma_mode && (is_last_cmd || i2c->cmd_err))
+			complete(&i2c->cmd_complete);
+	}
 
 	writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
 
@@ -348,15 +523,31 @@  static const struct i2c_algorithm mxs_i2c_algo = {
 	.functionality = mxs_i2c_func,
 };
 
+static bool mxs_i2c_dma_filter(struct dma_chan *chan, void *param)
+{
+	struct mxs_i2c_dev *i2c = param;
+
+	if (!mxs_dma_is_apbx(chan))
+		return false;
+
+	if (chan->chan_id != i2c->dmares->start)
+		return false;
+
+	chan->private = &i2c->dma_data;
+
+	return true;
+}
+
 static int __devinit mxs_i2c_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct mxs_i2c_platform_data *pdata = pdev->dev.platform_data;
 	struct mxs_i2c_dev *i2c;
 	struct i2c_adapter *adap;
-	struct resource *res;
+	struct resource *res, *dmares;
 	resource_size_t res_size;
-	int err, irq;
+	int err, irq, dmairq;
+	dma_cap_mask_t mask;
 
 	if (!pdata)
 		return -ENODEV;
@@ -366,7 +557,11 @@  static int __devinit mxs_i2c_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
+	dmares = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+	irq = platform_get_irq(pdev, 0);
+	dmairq = platform_get_irq(pdev, 1);
+
+	if (!res || !dmares || irq < 0 || dmairq < 0)
 		return -ENOENT;
 
 	res_size = resource_size(res);
@@ -377,10 +572,6 @@  static int __devinit mxs_i2c_probe(struct platform_device *pdev)
 	if (!i2c->regs)
 		return -EBUSY;
 
-	irq = platform_get_irq(pdev, 0);
-	if (irq < 0)
-		return irq;
-
 	err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
 	if (err)
 		return err;
@@ -394,6 +585,26 @@  static int __devinit mxs_i2c_probe(struct platform_device *pdev)
 	else if (pdata->speed_khz != 100)
 		dev_err(dev, "Invalid I2C speed selected, using 100kHz\n");
 
+	/*
+	 * The MXS I2C DMA mode is prefered and enabled by default.
+	 * The PIO mode is still supported, but should be used only
+	 * for debuging purposes etc.
+	 */
+	i2c->dma_mode = !pdata->use_pioqueue;
+
+	/* Setup the DMA */
+	if (i2c->dma_mode) {
+		i2c->dmares = dmares;
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+		i2c->dma_data.chan_irq = dmairq;
+		i2c->dmach = dma_request_channel(mask, mxs_i2c_dma_filter, i2c);
+		if (!i2c->dmach) {
+			dev_err(dev, "Failed to request dma\n");
+			return -ENODEV;
+		}
+	}
+
 	platform_set_drvdata(pdev, i2c);
 
 	/* Do reset to enforce correct startup after pinmuxing */
@@ -426,6 +637,9 @@  static int __devexit mxs_i2c_remove(struct platform_device *pdev)
 	if (ret)
 		return -EBUSY;
 
+	if (i2c->dmach)
+		dma_release_channel(i2c->dmach);
+
 	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
 			i2c->regs + MXS_I2C_QUEUECTRL_CLR);
 	writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
diff --git a/include/linux/i2c/mxs-i2c.h b/include/linux/i2c/mxs-i2c.h
index 781b080..16f23dc 100644
--- a/include/linux/i2c/mxs-i2c.h
+++ b/include/linux/i2c/mxs-i2c.h
@@ -16,6 +16,7 @@ 
 
 struct mxs_i2c_platform_data {
 	uint16_t	speed_khz;
+	bool		use_pioqueue;
 };
 
 #endif	/* __INCLUDE_LINUX_I2C_MXS_I2C_H__ */