Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 903 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
new file mode 100644
index 0000000000..36def0a9c9
--- /dev/null
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -0,0 +1,903 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Freescale MXS I2C bus driver
+ *
+ * Copyright (C) 2012-2013 Marek Vasut <marex@denx.de>
+ * Copyright (C) 2011-2012 Wolfram Sang, Pengutronix e.K.
+ *
+ * based on a (non-working) driver which was:
+ *
+ * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/platform_device.h>
+#include <linux/jiffies.h>
+#include <linux/io.h>
+#include <linux/stmp_device.h>
+#include <linux/of.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/dma/mxs-dma.h>
+
+#define DRIVER_NAME "mxs-i2c"
+
+#define MXS_I2C_CTRL0		(0x00)
+#define MXS_I2C_CTRL0_SET	(0x04)
+#define MXS_I2C_CTRL0_CLR	(0x08)
+
+#define MXS_I2C_CTRL0_SFTRST			0x80000000
+#define MXS_I2C_CTRL0_RUN			0x20000000
+#define MXS_I2C_CTRL0_SEND_NAK_ON_LAST		0x02000000
+#define MXS_I2C_CTRL0_PIO_MODE			0x01000000
+#define MXS_I2C_CTRL0_RETAIN_CLOCK		0x00200000
+#define MXS_I2C_CTRL0_POST_SEND_STOP		0x00100000
+#define MXS_I2C_CTRL0_PRE_SEND_START		0x00080000
+#define MXS_I2C_CTRL0_MASTER_MODE		0x00020000
+#define MXS_I2C_CTRL0_DIRECTION			0x00010000
+#define MXS_I2C_CTRL0_XFER_COUNT(v)		((v) & 0x0000FFFF)
+
+#define MXS_I2C_TIMING0		(0x10)
+#define MXS_I2C_TIMING1		(0x20)
+#define MXS_I2C_TIMING2		(0x30)
+
+#define MXS_I2C_CTRL1		(0x40)
+#define MXS_I2C_CTRL1_SET	(0x44)
+#define MXS_I2C_CTRL1_CLR	(0x48)
+
+#define MXS_I2C_CTRL1_CLR_GOT_A_NAK		0x10000000
+#define MXS_I2C_CTRL1_BUS_FREE_IRQ		0x80
+#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ	0x40
+#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ		0x20
+#define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ	0x10
+#define MXS_I2C_CTRL1_EARLY_TERM_IRQ		0x08
+#define MXS_I2C_CTRL1_MASTER_LOSS_IRQ		0x04
+#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ		0x02
+#define MXS_I2C_CTRL1_SLAVE_IRQ			0x01
+
+#define MXS_I2C_STAT		(0x50)
+#define MXS_I2C_STAT_GOT_A_NAK			0x10000000
+#define MXS_I2C_STAT_BUS_BUSY			0x00000800
+#define MXS_I2C_STAT_CLK_GEN_BUSY		0x00000400
+
+#define MXS_I2C_DATA(i2c)	((i2c->dev_type == MXS_I2C_V1) ? 0x60 : 0xa0)
+
+#define MXS_I2C_DEBUG0_CLR(i2c)	((i2c->dev_type == MXS_I2C_V1) ? 0x78 : 0xb8)
+
+#define MXS_I2C_DEBUG0_DMAREQ	0x80000000
+
+#define MXS_I2C_IRQ_MASK	(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
+				 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
+				 MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
+				 MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
+				 MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
+				 MXS_I2C_CTRL1_SLAVE_IRQ)
+
+
+#define MXS_CMD_I2C_SELECT	(MXS_I2C_CTRL0_RETAIN_CLOCK |	\
+				 MXS_I2C_CTRL0_PRE_SEND_START |	\
+				 MXS_I2C_CTRL0_MASTER_MODE |	\
+				 MXS_I2C_CTRL0_DIRECTION |	\
+				 MXS_I2C_CTRL0_XFER_COUNT(1))
+
+#define MXS_CMD_I2C_WRITE	(MXS_I2C_CTRL0_PRE_SEND_START |	\
+				 MXS_I2C_CTRL0_MASTER_MODE |	\
+				 MXS_I2C_CTRL0_DIRECTION)
+
+#define MXS_CMD_I2C_READ	(MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
+				 MXS_I2C_CTRL0_MASTER_MODE)
+
+enum mxs_i2c_devtype {
+	MXS_I2C_UNKNOWN = 0,
+	MXS_I2C_V1,
+	MXS_I2C_V2,
+};
+
+/**
+ * struct mxs_i2c_dev - per device, private MXS-I2C data
+ *
+ * @dev: driver model device node
+ * @dev_type: distinguish i.MX23/i.MX28 features
+ * @regs: IO registers pointer
+ * @cmd_complete: completion object for transaction wait
+ * @cmd_err: error code for last transaction
+ * @adapter: i2c subsystem adapter node
+ */
+struct mxs_i2c_dev {
+	struct device *dev;
+	enum mxs_i2c_devtype dev_type;
+	void __iomem *regs;
+	struct completion cmd_complete;
+	int cmd_err;
+	struct i2c_adapter adapter;
+
+	uint32_t timing0;
+	uint32_t timing1;
+	uint32_t timing2;
+
+	/* DMA support components */
+	struct dma_chan			*dmach;
+	uint32_t			pio_data[2];
+	uint32_t			addr_data;
+	struct scatterlist		sg_io[2];
+	bool				dma_read;
+};
+
+static int mxs_i2c_reset(struct mxs_i2c_dev *i2c)
+{
+	int ret = stmp_reset_block(i2c->regs);
+	if (ret)
+		return ret;
+
+	/*
+	 * Configure timing for the I2C block. The I2C TIMING2 register has to
+	 * be programmed with this particular magic number. The rest is derived
+	 * from the XTAL speed and requested I2C speed.
+	 *
+	 * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
+	 */
+	writel(i2c->timing0, i2c->regs + MXS_I2C_TIMING0);
+	writel(i2c->timing1, i2c->regs + MXS_I2C_TIMING1);
+	writel(i2c->timing2, i2c->regs + MXS_I2C_TIMING2);
+
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
+
+	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, u8 *buf, uint32_t flags)
+{
+	struct dma_async_tx_descriptor *desc;
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+
+	i2c->addr_data = i2c_8bit_addr_from_msg(msg);
+
+	if (msg->flags & I2C_M_RD) {
+		i2c->dma_read = true;
+
+		/*
+		 * 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 |
+					MXS_DMA_CTRL_WAIT4END);
+		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], 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 |
+					MXS_DMA_CTRL_WAIT4END);
+		if (!desc) {
+			dev_err(i2c->dev,
+				"Failed to get DMA data write descriptor.\n");
+			goto read_init_dma_fail;
+		}
+	} else {
+		i2c->dma_read = false;
+
+		/*
+		 * 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], 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 |
+					MXS_DMA_CTRL_WAIT4END);
+		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:
+	dmaengine_terminate_sync(i2c->dmach);
+	return -EINVAL;
+
+/* Write failpath. */
+write_init_dma_fail:
+	dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+write_init_pio_fail:
+	dmaengine_terminate_sync(i2c->dmach);
+	return -EINVAL;
+}
+
+static int mxs_i2c_pio_wait_xfer_end(struct mxs_i2c_dev *i2c)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+	while (readl(i2c->regs + MXS_I2C_CTRL0) & MXS_I2C_CTRL0_RUN) {
+		if (readl(i2c->regs + MXS_I2C_CTRL1) &
+				MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
+			return -ENXIO;
+		if (time_after(jiffies, timeout))
+			return -ETIMEDOUT;
+		cond_resched();
+	}
+
+	return 0;
+}
+
+static int mxs_i2c_pio_check_error_state(struct mxs_i2c_dev *i2c)
+{
+	u32 state;
+
+	state = readl(i2c->regs + MXS_I2C_CTRL1_CLR) & MXS_I2C_IRQ_MASK;
+
+	if (state & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
+		i2c->cmd_err = -ENXIO;
+	else if (state & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
+			  MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
+			  MXS_I2C_CTRL1_SLAVE_STOP_IRQ |
+			  MXS_I2C_CTRL1_SLAVE_IRQ))
+		i2c->cmd_err = -EIO;
+
+	return i2c->cmd_err;
+}
+
+static void mxs_i2c_pio_trigger_cmd(struct mxs_i2c_dev *i2c, u32 cmd)
+{
+	u32 reg;
+
+	writel(cmd, i2c->regs + MXS_I2C_CTRL0);
+
+	/* readback makes sure the write is latched into hardware */
+	reg = readl(i2c->regs + MXS_I2C_CTRL0);
+	reg |= MXS_I2C_CTRL0_RUN;
+	writel(reg, i2c->regs + MXS_I2C_CTRL0);
+}
+
+/*
+ * Start WRITE transaction on the I2C bus. By studying i.MX23 datasheet,
+ * CTRL0::PIO_MODE bit description clarifies the order in which the registers
+ * must be written during PIO mode operation. First, the CTRL0 register has
+ * to be programmed with all the necessary bits but the RUN bit. Then the
+ * payload has to be written into the DATA register. Finally, the transmission
+ * is executed by setting the RUN bit in CTRL0.
+ */
+static void mxs_i2c_pio_trigger_write_cmd(struct mxs_i2c_dev *i2c, u32 cmd,
+					  u32 data)
+{
+	writel(cmd, i2c->regs + MXS_I2C_CTRL0);
+
+	if (i2c->dev_type == MXS_I2C_V1)
+		writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_SET);
+
+	writel(data, i2c->regs + MXS_I2C_DATA(i2c));
+	writel(MXS_I2C_CTRL0_RUN, i2c->regs + MXS_I2C_CTRL0_SET);
+}
+
+static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
+			struct i2c_msg *msg, uint32_t flags)
+{
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+	uint32_t addr_data = i2c_8bit_addr_from_msg(msg);
+	uint32_t data = 0;
+	int i, ret, xlen = 0, xmit = 0;
+	uint32_t start;
+
+	/* Mute IRQs coming from this block. */
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_CLR);
+
+	/*
+	 * MX23 idea:
+	 * - Enable CTRL0::PIO_MODE (1 << 24)
+	 * - Enable CTRL1::ACK_MODE (1 << 27)
+	 *
+	 * WARNING! The MX23 is broken in some way, even if it claims
+	 * to support PIO, when we try to transfer any amount of data
+	 * that is not aligned to 4 bytes, the DMA engine will have
+	 * bits in DEBUG1::DMA_BYTES_ENABLES still set even after the
+	 * transfer. This in turn will mess up the next transfer as
+	 * the block it emit one byte write onto the bus terminated
+	 * with a NAK+STOP. A possible workaround is to reset the IP
+	 * block after every PIO transmission, which might just work.
+	 *
+	 * NOTE: The CTRL0::PIO_MODE description is important, since
+	 * it outlines how the PIO mode is really supposed to work.
+	 */
+	if (msg->flags & I2C_M_RD) {
+		/*
+		 * PIO READ transfer:
+		 *
+		 * This transfer MUST be limited to 4 bytes maximum. It is not
+		 * possible to transfer more than four bytes via PIO, since we
+		 * can not in any way make sure we can read the data from the
+		 * DATA register fast enough. Besides, the RX FIFO is only four
+		 * bytes deep, thus we can only really read up to four bytes at
+		 * time. Finally, there is no bit indicating us that new data
+		 * arrived at the FIFO and can thus be fetched from the DATA
+		 * register.
+		 */
+		BUG_ON(msg->len > 4);
+
+		/* SELECT command. */
+		mxs_i2c_pio_trigger_write_cmd(i2c, MXS_CMD_I2C_SELECT,
+					      addr_data);
+
+		ret = mxs_i2c_pio_wait_xfer_end(i2c);
+		if (ret) {
+			dev_dbg(i2c->dev,
+				"PIO: Failed to send SELECT command!\n");
+			goto cleanup;
+		}
+
+		/* READ command. */
+		mxs_i2c_pio_trigger_cmd(i2c,
+					MXS_CMD_I2C_READ | flags |
+					MXS_I2C_CTRL0_XFER_COUNT(msg->len));
+
+		ret = mxs_i2c_pio_wait_xfer_end(i2c);
+		if (ret) {
+			dev_dbg(i2c->dev,
+				"PIO: Failed to send READ command!\n");
+			goto cleanup;
+		}
+
+		data = readl(i2c->regs + MXS_I2C_DATA(i2c));
+		for (i = 0; i < msg->len; i++) {
+			msg->buf[i] = data & 0xff;
+			data >>= 8;
+		}
+	} else {
+		/*
+		 * PIO WRITE transfer:
+		 *
+		 * The code below implements clock stretching to circumvent
+		 * the possibility of kernel not being able to supply data
+		 * fast enough. It is possible to transfer arbitrary amount
+		 * of data using PIO write.
+		 */
+
+		/*
+		 * The LSB of data buffer is the first byte blasted across
+		 * the bus. Higher order bytes follow. Thus the following
+		 * filling schematic.
+		 */
+
+		data = addr_data << 24;
+
+		/* Start the transfer with START condition. */
+		start = MXS_I2C_CTRL0_PRE_SEND_START;
+
+		/* If the transfer is long, use clock stretching. */
+		if (msg->len > 3)
+			start |= MXS_I2C_CTRL0_RETAIN_CLOCK;
+
+		for (i = 0; i < msg->len; i++) {
+			data >>= 8;
+			data |= (msg->buf[i] << 24);
+
+			xmit = 0;
+
+			/* This is the last transfer of the message. */
+			if (i + 1 == msg->len) {
+				/* Add optional STOP flag. */
+				start |= flags;
+				/* Remove RETAIN_CLOCK bit. */
+				start &= ~MXS_I2C_CTRL0_RETAIN_CLOCK;
+				xmit = 1;
+			}
+
+			/* Four bytes are ready in the "data" variable. */
+			if ((i & 3) == 2)
+				xmit = 1;
+
+			/* Nothing interesting happened, continue stuffing. */
+			if (!xmit)
+				continue;
+
+			/*
+			 * Compute the size of the transfer and shift the
+			 * data accordingly.
+			 *
+			 * i = (4k + 0) .... xlen = 2
+			 * i = (4k + 1) .... xlen = 3
+			 * i = (4k + 2) .... xlen = 4
+			 * i = (4k + 3) .... xlen = 1
+			 */
+
+			if ((i % 4) == 3)
+				xlen = 1;
+			else
+				xlen = (i % 4) + 2;
+
+			data >>= (4 - xlen) * 8;
+
+			dev_dbg(i2c->dev,
+				"PIO: len=%i pos=%i total=%i [W%s%s%s]\n",
+				xlen, i, msg->len,
+				start & MXS_I2C_CTRL0_PRE_SEND_START ? "S" : "",
+				start & MXS_I2C_CTRL0_POST_SEND_STOP ? "E" : "",
+				start & MXS_I2C_CTRL0_RETAIN_CLOCK ? "C" : "");
+
+			writel(MXS_I2C_DEBUG0_DMAREQ,
+			       i2c->regs + MXS_I2C_DEBUG0_CLR(i2c));
+
+			mxs_i2c_pio_trigger_write_cmd(i2c,
+				start | MXS_I2C_CTRL0_MASTER_MODE |
+				MXS_I2C_CTRL0_DIRECTION |
+				MXS_I2C_CTRL0_XFER_COUNT(xlen), data);
+
+			/* The START condition is sent only once. */
+			start &= ~MXS_I2C_CTRL0_PRE_SEND_START;
+
+			/* Wait for the end of the transfer. */
+			ret = mxs_i2c_pio_wait_xfer_end(i2c);
+			if (ret) {
+				dev_dbg(i2c->dev,
+					"PIO: Failed to finish WRITE cmd!\n");
+				break;
+			}
+
+			/* Check NAK here. */
+			ret = readl(i2c->regs + MXS_I2C_STAT) &
+				    MXS_I2C_STAT_GOT_A_NAK;
+			if (ret) {
+				ret = -ENXIO;
+				goto cleanup;
+			}
+		}
+	}
+
+	/* make sure we capture any occurred error into cmd_err */
+	ret = mxs_i2c_pio_check_error_state(i2c);
+
+cleanup:
+	/* Clear any dangling IRQs and re-enable interrupts. */
+	writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
+
+	/* Clear the PIO_MODE on i.MX23 */
+	if (i2c->dev_type == MXS_I2C_V1)
+		writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_CLR);
+
+	return ret;
+}
+
+/*
+ * Low level master read/write transaction.
+ */
+static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
+				int stop)
+{
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+	int ret;
+	int flags;
+	u8 *dma_buf;
+	int use_pio = 0;
+	unsigned long time_left;
+
+	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);
+
+	/*
+	 * The MX28 I2C IP block can only do PIO READ for transfer of to up
+	 * 4 bytes of length. The write transfer is not limited as it can use
+	 * clock stretching to avoid FIFO underruns.
+	 */
+	if ((msg->flags & I2C_M_RD) && (msg->len <= 4))
+		use_pio = 1;
+	if (!(msg->flags & I2C_M_RD) && (msg->len < 7))
+		use_pio = 1;
+
+	i2c->cmd_err = 0;
+	if (use_pio) {
+		ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
+		/* No need to reset the block if NAK was received. */
+		if (ret && (ret != -ENXIO))
+			mxs_i2c_reset(i2c);
+	} else {
+		dma_buf = i2c_get_dma_safe_msg_buf(msg, 1);
+		if (!dma_buf)
+			return -ENOMEM;
+
+		reinit_completion(&i2c->cmd_complete);
+		ret = mxs_i2c_dma_setup_xfer(adap, msg, dma_buf, flags);
+		if (ret) {
+			i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
+			return ret;
+		}
+
+		time_left = wait_for_completion_timeout(&i2c->cmd_complete,
+						msecs_to_jiffies(1000));
+		i2c_put_dma_safe_msg_buf(dma_buf, msg, true);
+		if (!time_left)
+			goto timeout;
+
+		ret = i2c->cmd_err;
+	}
+
+	if (ret == -ENXIO) {
+		/*
+		 * If the transfer fails with a NAK from the slave the
+		 * controller halts until it gets told to return to idle state.
+		 */
+		writel(MXS_I2C_CTRL1_CLR_GOT_A_NAK,
+		       i2c->regs + MXS_I2C_CTRL1_SET);
+	}
+
+	/*
+	 * WARNING!
+	 * The i.MX23 is strange. After each and every operation, it's I2C IP
+	 * block must be reset, otherwise the IP block will misbehave. This can
+	 * be observed on the bus by the block sending out one single byte onto
+	 * the bus. In case such an error happens, bit 27 will be set in the
+	 * DEBUG0 register. This bit is not documented in the i.MX23 datasheet
+	 * and is marked as "TBD" instead. To reset this bit to a correct state,
+	 * reset the whole block. Since the block reset does not take long, do
+	 * reset the block after every transfer to play safe.
+	 */
+	if (i2c->dev_type == MXS_I2C_V1)
+		mxs_i2c_reset(i2c);
+
+	dev_dbg(i2c->dev, "Done with err=%d\n", ret);
+
+	return ret;
+
+timeout:
+	dev_dbg(i2c->dev, "Timeout!\n");
+	mxs_i2c_dma_finish(i2c);
+	ret = mxs_i2c_reset(i2c);
+	if (ret)
+		return ret;
+
+	return -ETIMEDOUT;
+}
+
+static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+			int num)
+{
+	int i;
+	int err;
+
+	for (i = 0; i < num; i++) {
+		err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
+		if (err)
+			return err;
+	}
+
+	return num;
+}
+
+static u32 mxs_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
+{
+	struct mxs_i2c_dev *i2c = dev_id;
+	u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
+
+	if (!stat)
+		return IRQ_NONE;
+
+	if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
+		i2c->cmd_err = -ENXIO;
+	else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
+		    MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
+		    MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
+		/* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
+		i2c->cmd_err = -EIO;
+
+	writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
+
+	return IRQ_HANDLED;
+}
+
+static const struct i2c_algorithm mxs_i2c_algo = {
+	.master_xfer = mxs_i2c_xfer,
+	.functionality = mxs_i2c_func,
+};
+
+static const struct i2c_adapter_quirks mxs_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+};
+
+static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, uint32_t speed)
+{
+	/* The I2C block clock runs at 24MHz */
+	const uint32_t clk = 24000000;
+	uint32_t divider;
+	uint16_t high_count, low_count, rcv_count, xmit_count;
+	uint32_t bus_free, leadin;
+	struct device *dev = i2c->dev;
+
+	divider = DIV_ROUND_UP(clk, speed);
+
+	if (divider < 25) {
+		/*
+		 * limit the divider, so that min(low_count, high_count)
+		 * is >= 1
+		 */
+		divider = 25;
+		dev_warn(dev,
+			"Speed too high (%u.%03u kHz), using %u.%03u kHz\n",
+			speed / 1000, speed % 1000,
+			clk / divider / 1000, clk / divider % 1000);
+	} else if (divider > 1897) {
+		/*
+		 * limit the divider, so that max(low_count, high_count)
+		 * cannot exceed 1023
+		 */
+		divider = 1897;
+		dev_warn(dev,
+			"Speed too low (%u.%03u kHz), using %u.%03u kHz\n",
+			speed / 1000, speed % 1000,
+			clk / divider / 1000, clk / divider % 1000);
+	}
+
+	/*
+	 * The I2C spec specifies the following timing data:
+	 *                          standard mode  fast mode Bitfield name
+	 * tLOW (SCL LOW period)     4700 ns        1300 ns
+	 * tHIGH (SCL HIGH period)   4000 ns         600 ns
+	 * tSU;DAT (data setup time)  250 ns         100 ns
+	 * tHD;STA (START hold time) 4000 ns         600 ns
+	 * tBUF (bus free time)      4700 ns        1300 ns
+	 *
+	 * The hardware (of the i.MX28 at least) seems to add 2 additional
+	 * clock cycles to the low_count and 7 cycles to the high_count.
+	 * This is compensated for by subtracting the respective constants
+	 * from the values written to the timing registers.
+	 */
+	if (speed > I2C_MAX_STANDARD_MODE_FREQ) {
+		/* fast mode */
+		low_count = DIV_ROUND_CLOSEST(divider * 13, (13 + 6));
+		high_count = DIV_ROUND_CLOSEST(divider * 6, (13 + 6));
+		leadin = DIV_ROUND_UP(600 * (clk / 1000000), 1000);
+		bus_free = DIV_ROUND_UP(1300 * (clk / 1000000), 1000);
+	} else {
+		/* normal mode */
+		low_count = DIV_ROUND_CLOSEST(divider * 47, (47 + 40));
+		high_count = DIV_ROUND_CLOSEST(divider * 40, (47 + 40));
+		leadin = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
+		bus_free = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
+	}
+	rcv_count = high_count * 3 / 8;
+	xmit_count = low_count * 3 / 8;
+
+	dev_dbg(dev,
+		"speed=%u(actual %u) divider=%u low=%u high=%u xmit=%u rcv=%u leadin=%u bus_free=%u\n",
+		speed, clk / divider, divider, low_count, high_count,
+		xmit_count, rcv_count, leadin, bus_free);
+
+	low_count -= 2;
+	high_count -= 7;
+	i2c->timing0 = (high_count << 16) | rcv_count;
+	i2c->timing1 = (low_count << 16) | xmit_count;
+	i2c->timing2 = (bus_free << 16 | leadin);
+}
+
+static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
+{
+	uint32_t speed;
+	struct device *dev = i2c->dev;
+	struct device_node *node = dev->of_node;
+	int ret;
+
+	ret = of_property_read_u32(node, "clock-frequency", &speed);
+	if (ret) {
+		dev_warn(dev, "No I2C speed selected, using 100kHz\n");
+		speed = I2C_MAX_STANDARD_MODE_FREQ;
+	}
+
+	mxs_i2c_derive_timing(i2c, speed);
+
+	return 0;
+}
+
+static const struct of_device_id mxs_i2c_dt_ids[] = {
+	{ .compatible = "fsl,imx23-i2c", .data = (void *)MXS_I2C_V1, },
+	{ .compatible = "fsl,imx28-i2c", .data = (void *)MXS_I2C_V2, },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
+
+static int mxs_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mxs_i2c_dev *i2c;
+	struct i2c_adapter *adap;
+	int err, irq;
+
+	i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	i2c->dev_type = (uintptr_t)of_device_get_match_data(&pdev->dev);
+
+	i2c->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(i2c->regs))
+		return PTR_ERR(i2c->regs);
+
+	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;
+
+	i2c->dev = dev;
+
+	init_completion(&i2c->cmd_complete);
+
+	if (dev->of_node) {
+		err = mxs_i2c_get_ofdata(i2c);
+		if (err)
+			return err;
+	}
+
+	/* Setup the DMA */
+	i2c->dmach = dma_request_chan(dev, "rx-tx");
+	if (IS_ERR(i2c->dmach)) {
+		return dev_err_probe(dev, PTR_ERR(i2c->dmach),
+				     "Failed to request dma\n");
+	}
+
+	platform_set_drvdata(pdev, i2c);
+
+	/* Do reset to enforce correct startup after pinmuxing */
+	err = mxs_i2c_reset(i2c);
+	if (err)
+		return err;
+
+	adap = &i2c->adapter;
+	strscpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
+	adap->owner = THIS_MODULE;
+	adap->algo = &mxs_i2c_algo;
+	adap->quirks = &mxs_i2c_quirks;
+	adap->dev.parent = dev;
+	adap->nr = pdev->id;
+	adap->dev.of_node = pdev->dev.of_node;
+	i2c_set_adapdata(adap, i2c);
+	err = i2c_add_numbered_adapter(adap);
+	if (err) {
+		writel(MXS_I2C_CTRL0_SFTRST,
+				i2c->regs + MXS_I2C_CTRL0_SET);
+		return err;
+	}
+
+	return 0;
+}
+
+static void mxs_i2c_remove(struct platform_device *pdev)
+{
+	struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adapter);
+
+	if (i2c->dmach)
+		dma_release_channel(i2c->dmach);
+
+	writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
+}
+
+static struct platform_driver mxs_i2c_driver = {
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .of_match_table = mxs_i2c_dt_ids,
+		   },
+	.probe = mxs_i2c_probe,
+	.remove_new = mxs_i2c_remove,
+};
+
+static int __init mxs_i2c_init(void)
+{
+	return platform_driver_register(&mxs_i2c_driver);
+}
+subsys_initcall(mxs_i2c_init);
+
+static void __exit mxs_i2c_exit(void)
+{
+	platform_driver_unregister(&mxs_i2c_driver);
+}
+module_exit(mxs_i2c_exit);
+
+MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
+MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("MXS I2C Bus Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);