[PATCH v2] i2c: tegra: Add i2c support

[Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>]

Adds I2C bus driver for nVidia Tegra SoCs.  Tegra includes 4 I2C
controllers, one of which is inside the Dynamic Voltage Controller
and has a slightly different register map.

Signed-off-by: Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
---
v2: fixes comments from Ben Dooks and Stephen Warren

 drivers/i2c/busses/Kconfig     |    7 +
 drivers/i2c/busses/Makefile    |    1 +
 drivers/i2c/busses/i2c-tegra.c |  700 ++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c-tegra.h      |   25 ++
 4 files changed, 733 insertions(+), 0 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-tegra.c
 create mode 100644 include/linux/i2c-tegra.h

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 113505a..a5f48dc 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -607,6 +607,13 @@ config I2C_STU300
 	  This driver can also be built as a module. If so, the module
 	  will be called i2c-stu300.
 
+config I2C_TEGRA
+	tristate "NVIDIA Tegra internal I2C controller"
+	depends on ARCH_TEGRA
+	help
+	  If you say yes to this option, support will be included for the
+	  I2C controller embedded in NVIDIA Tegra SOCs
+
 config I2C_VERSATILE
 	tristate "ARM Versatile/Realview I2C bus support"
 	depends on ARCH_VERSATILE || ARCH_REALVIEW || ARCH_VEXPRESS
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 9d2d0ec..a0d4afe 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_I2C_SH7760)	+= i2c-sh7760.o
 obj-$(CONFIG_I2C_SH_MOBILE)	+= i2c-sh_mobile.o
 obj-$(CONFIG_I2C_SIMTEC)	+= i2c-simtec.o
 obj-$(CONFIG_I2C_STU300)	+= i2c-stu300.o
+obj-$(CONFIG_I2C_TEGRA)		+= i2c-tegra.o
 obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o
 obj-$(CONFIG_I2C_OCTEON)	+= i2c-octeon.o
 obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
new file mode 100644
index 0000000..3921f66
--- /dev/null
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -0,0 +1,700 @@
+/*
+ * drivers/i2c/busses/i2c-tegra.c
+ *
+ * Copyright (C) 2010 Google, Inc.
+ * Author: Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/i2c-tegra.h>
+
+#include <asm/unaligned.h>
+
+#include <mach/clk.h>
+
+#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
+#define BYTES_PER_FIFO_WORD 4
+
+#define I2C_CNFG				0x000
+#define I2C_CNFG_PACKET_MODE_EN			(1<<10)
+#define I2C_CNFG_NEW_MASTER_FSM			(1<<11)
+#define I2C_SL_CNFG				0x020
+#define I2C_SL_CNFG_NEWSL			(1<<2)
+#define I2C_SL_ADDR1				0x02c
+#define I2C_TX_FIFO				0x050
+#define I2C_RX_FIFO				0x054
+#define I2C_PACKET_TRANSFER_STATUS		0x058
+#define I2C_FIFO_CONTROL			0x05c
+#define I2C_FIFO_CONTROL_TX_FLUSH		(1<<1)
+#define I2C_FIFO_CONTROL_RX_FLUSH		(1<<0)
+#define I2C_FIFO_CONTROL_TX_TRIG_SHIFT		5
+#define I2C_FIFO_CONTROL_RX_TRIG_SHIFT		2
+#define I2C_FIFO_STATUS				0x060
+#define I2C_FIFO_STATUS_TX_MASK			0xF0
+#define I2C_FIFO_STATUS_TX_SHIFT		4
+#define I2C_FIFO_STATUS_RX_MASK			0x0F
+#define I2C_FIFO_STATUS_RX_SHIFT		0
+#define I2C_INT_MASK				0x064
+#define I2C_INT_STATUS				0x068
+#define I2C_INT_PACKET_XFER_COMPLETE		(1<<7)
+#define I2C_INT_ALL_PACKETS_XFER_COMPLETE	(1<<6)
+#define I2C_INT_TX_FIFO_OVERFLOW		(1<<5)
+#define I2C_INT_RX_FIFO_UNDERFLOW		(1<<4)
+#define I2C_INT_NO_ACK				(1<<3)
+#define I2C_INT_ARBITRATION_LOST		(1<<2)
+#define I2C_INT_TX_FIFO_DATA_REQ		(1<<1)
+#define I2C_INT_RX_FIFO_DATA_REQ		(1<<0)
+#define I2C_CLK_DIVISOR				0x06c
+
+#define DVC_CTRL_REG1				0x000
+#define DVC_CTRL_REG1_INTR_EN			(1<<10)
+#define DVC_CTRL_REG2				0x004
+#define DVC_CTRL_REG3				0x008
+#define DVC_CTRL_REG3_SW_PROG			(1<<26)
+#define DVC_CTRL_REG3_I2C_DONE_INTR_EN		(1<<30)
+#define DVC_STATUS				0x00c
+#define DVC_STATUS_I2C_DONE_INTR		(1<<30)
+
+#define I2C_ERR_NONE				0x00
+#define I2C_ERR_NO_ACK				0x01
+#define I2C_ERR_ARBITRATION_LOST		0x02
+
+#define PACKET_HEADER0_HEADER_SIZE_SHIFT	28
+#define PACKET_HEADER0_PACKET_ID_SHIFT		16
+#define PACKET_HEADER0_CONT_ID_SHIFT		12
+#define PACKET_HEADER0_PROTOCOL_I2C		(1<<4)
+
+#define I2C_HEADER_HIGHSPEED_MODE		(1<<22)
+#define I2C_HEADER_CONT_ON_NAK			(1<<21)
+#define I2C_HEADER_SEND_START_BYTE		(1<<20)
+#define I2C_HEADER_READ				(1<<19)
+#define I2C_HEADER_10BIT_ADDR			(1<<18)
+#define I2C_HEADER_IE_ENABLE			(1<<17)
+#define I2C_HEADER_REPEAT_START			(1<<16)
+#define I2C_HEADER_MASTER_ADDR_SHIFT		12
+#define I2C_HEADER_SLAVE_ADDR_SHIFT		1
+
+/**
+ * struct tegra_i2c_dev	- per device i2c context
+ * @dev: device reference for power management
+ * @adapter: core i2c layer adapter information
+ * @clk: clock reference for i2c controller
+ * @i2c_clk: clock reference for i2c bus
+ * @iomem: memory resource for registers
+ * @base: ioremapped registers cookie
+ * @cont_id: i2c controller id, used for for packet header
+ * @irq: irq number of transfer complete interrupt
+ * @is_dvc: identifies the DVC i2c controller, has a different register layout
+ * @msg_complete: transfer completion notifier
+ * @msg_err: error code for completed message
+ * @msg_buf: pointer to current message data
+ * @msg_buf_remaining: size of unsent data in the message buffer
+ * @msg_read: identifies read transfers
+ * @bus_clk_rate: current i2c bus clock rate
+ * @is_suspended: prevents i2c controller accesses after suspend is called
+ */
+struct tegra_i2c_dev {
+	struct device *dev;
+	struct i2c_adapter adapter;
+	struct clk *clk;
+	struct clk *i2c_clk;
+	struct resource *iomem;
+	void __iomem *base;
+	int cont_id;
+	int irq;
+	int is_dvc;
+	struct completion msg_complete;
+	int msg_err;
+	u8 *msg_buf;
+	size_t msg_buf_remaining;
+	int msg_read;
+	unsigned long bus_clk_rate;
+	bool is_suspended;
+};
+
+static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned long reg)
+{
+	writel(val, i2c_dev->base + reg);
+}
+
+static u32 dvc_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
+{
+	return readl(i2c_dev->base + reg);
+}
+
+/*
+ * i2c_writel and i2c_readl will offset the register if necessary to talk
+ * to the I2C block inside the DVC block
+ */
+static unsigned long tegra_i2c_reg_addr(struct tegra_i2c_dev *i2c_dev,
+	unsigned long reg)
+{
+	if (i2c_dev->is_dvc)
+		reg += (reg >= I2C_TX_FIFO) ? 0x10 : 0x40;
+	return reg;
+}
+
+static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
+	unsigned long reg)
+{
+	writel(val, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
+}
+
+static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
+{
+	return readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
+}
+
+static void i2c_writesl(struct tegra_i2c_dev *i2c_dev, void *data,
+	unsigned long reg, int len)
+{
+	writesl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
+}
+
+static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data,
+	unsigned long reg, int len)
+{
+	readsl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
+}
+
+static void tegra_i2c_mask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
+{
+	u32 int_mask = i2c_readl(i2c_dev, I2C_INT_MASK);
+	int_mask &= ~mask;
+	i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
+}
+
+static void tegra_i2c_unmask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
+{
+	u32 int_mask = i2c_readl(i2c_dev, I2C_INT_MASK);
+	int_mask |= mask;
+	i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
+}
+
+static int tegra_i2c_flush_fifos(struct tegra_i2c_dev *i2c_dev)
+{
+	unsigned long timeout = jiffies + HZ;
+	u32 val = i2c_readl(i2c_dev, I2C_FIFO_CONTROL);
+	val |= I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH;
+	i2c_writel(i2c_dev, val, I2C_FIFO_CONTROL);
+
+	while (i2c_readl(i2c_dev, I2C_FIFO_CONTROL) &
+		(I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH)) {
+		if (time_after(jiffies, timeout)) {
+			dev_warn(i2c_dev->dev, "timeout waiting for fifo flush\n");
+			return -ETIMEDOUT;
+		}
+		msleep(1);
+	}
+	return 0;
+}
+
+static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
+{
+	u32 val;
+	int rx_fifo_avail;
+	u8 *buf = i2c_dev->msg_buf;
+	size_t buf_remaining = i2c_dev->msg_buf_remaining;
+	int words_to_transfer;
+
+	val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
+	rx_fifo_avail = (val & I2C_FIFO_STATUS_RX_MASK) >>
+		I2C_FIFO_STATUS_RX_SHIFT;
+
+	/* Rounds down to not include partial word at the end of buf */
+	words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
+	if (words_to_transfer > rx_fifo_avail)
+		words_to_transfer = rx_fifo_avail;
+
+	i2c_readsl(i2c_dev, buf, I2C_RX_FIFO, words_to_transfer);
+
+	buf += words_to_transfer * BYTES_PER_FIFO_WORD;
+	buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
+	rx_fifo_avail -= words_to_transfer;
+
+	/*
+	 * If there is a partial word at the end of buf, handle it manually to
+	 * prevent overwriting past the end of buf
+	 */
+	if (rx_fifo_avail > 0 && buf_remaining > 0) {
+		BUG_ON(buf_remaining > 3);
+		val = i2c_readl(i2c_dev, I2C_RX_FIFO);
+		memcpy(buf, &val, buf_remaining);
+		buf_remaining = 0;
+		rx_fifo_avail--;
+	}
+
+	BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
+	i2c_dev->msg_buf_remaining = buf_remaining;
+	i2c_dev->msg_buf = buf;
+	return 0;
+}
+
+static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
+{
+	u32 val;
+	int tx_fifo_avail;
+	u8 *buf = i2c_dev->msg_buf;
+	size_t buf_remaining = i2c_dev->msg_buf_remaining;
+	int words_to_transfer;
+
+	val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
+	tx_fifo_avail = (val & I2C_FIFO_STATUS_TX_MASK) >>
+		I2C_FIFO_STATUS_TX_SHIFT;
+
+	/* Rounds down to not include partial word at the end of buf */
+	words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
+	if (words_to_transfer > tx_fifo_avail)
+		words_to_transfer = tx_fifo_avail;
+
+	i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
+
+	buf += words_to_transfer * BYTES_PER_FIFO_WORD;
+	buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
+	tx_fifo_avail -= words_to_transfer;
+
+	/*
+	 * If there is a partial word at the end of buf, handle it manually to
+	 * prevent reading past the end of buf, which could cross a page
+	 * boundary and fault.
+	 */
+	if (tx_fifo_avail > 0 && buf_remaining > 0) {
+		BUG_ON(buf_remaining > 3);
+		memcpy(&val, buf, buf_remaining);
+		i2c_writel(i2c_dev, val, I2C_TX_FIFO);
+		buf_remaining = 0;
+		tx_fifo_avail--;
+	}
+
+	BUG_ON(tx_fifo_avail > 0 && buf_remaining > 0);
+	i2c_dev->msg_buf_remaining = buf_remaining;
+	i2c_dev->msg_buf = buf;
+	return 0;
+}
+
+/*
+ * One of the Tegra I2C blocks is inside the DVC (Digital Voltage Controller)
+ * block.  This block is identical to the rest of the I2C blocks, except that
+ * it only supports master mode, it has registers moved around, and it needs
+ * some extra init to get it into I2C mode.  The register moves are handled
+ * by i2c_readl and i2c_writel
+ */
+static void tegra_dvc_init(struct tegra_i2c_dev *i2c_dev)
+{
+	u32 val = 0;
+	val = dvc_readl(i2c_dev, DVC_CTRL_REG3);
+	val |= DVC_CTRL_REG3_SW_PROG;
+	val |= DVC_CTRL_REG3_I2C_DONE_INTR_EN;
+	dvc_writel(i2c_dev, val, DVC_CTRL_REG3);
+
+	val = dvc_readl(i2c_dev, DVC_CTRL_REG1);
+	val |= DVC_CTRL_REG1_INTR_EN;
+	dvc_writel(i2c_dev, val, DVC_CTRL_REG1);
+}
+
+static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
+{
+	u32 val;
+	int err = 0;
+
+	clk_enable(i2c_dev->clk);
+
+	tegra_periph_reset_assert(i2c_dev->clk);
+	udelay(2);
+	tegra_periph_reset_deassert(i2c_dev->clk);
+
+	if (i2c_dev->is_dvc)
+		tegra_dvc_init(i2c_dev);
+
+	val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN;
+	i2c_writel(i2c_dev, val, I2C_CNFG);
+	i2c_writel(i2c_dev, 0, I2C_INT_MASK);
+	clk_set_rate(i2c_dev->clk, i2c_dev->bus_clk_rate * 8);
+
+	val = 7 << I2C_FIFO_CONTROL_TX_TRIG_SHIFT |
+		0 << I2C_FIFO_CONTROL_RX_TRIG_SHIFT;
+	i2c_writel(i2c_dev, val, I2C_FIFO_CONTROL);
+
+	if (tegra_i2c_flush_fifos(i2c_dev))
+		err = -ETIMEDOUT;
+
+	clk_disable(i2c_dev->clk);
+	return err;
+}
+
+static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
+{
+	u32 status;
+	const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
+	struct tegra_i2c_dev *i2c_dev = dev_id;
+
+	status = i2c_readl(i2c_dev, I2C_INT_STATUS);
+
+	if (status == 0) {
+		dev_warn(i2c_dev->dev, "interrupt with no status\n");
+		return IRQ_NONE;
+	}
+
+	if (unlikely(status & status_err)) {
+		if (status & I2C_INT_NO_ACK)
+			i2c_dev->msg_err |= I2C_ERR_NO_ACK;
+		if (status & I2C_INT_ARBITRATION_LOST)
+			i2c_dev->msg_err |= I2C_ERR_ARBITRATION_LOST;
+		complete(&i2c_dev->msg_complete);
+		goto err;
+	}
+
+	if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
+		if (i2c_dev->msg_buf_remaining)
+			tegra_i2c_empty_rx_fifo(i2c_dev);
+		else
+			BUG();
+	}
+
+	if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
+		if (i2c_dev->msg_buf_remaining)
+			tegra_i2c_fill_tx_fifo(i2c_dev);
+		else
+			tegra_i2c_mask_irq(i2c_dev, I2C_INT_TX_FIFO_DATA_REQ);
+	}
+
+	if ((status & I2C_INT_PACKET_XFER_COMPLETE) &&
+			!i2c_dev->msg_buf_remaining)
+		complete(&i2c_dev->msg_complete);
+
+	i2c_writel(i2c_dev, status, I2C_INT_STATUS);
+	if (i2c_dev->is_dvc)
+		dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);
+	return IRQ_HANDLED;
+err:
+	/* An error occured, mask all interrupts */
+	tegra_i2c_mask_irq(i2c_dev, I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST |
+		I2C_INT_PACKET_XFER_COMPLETE | I2C_INT_TX_FIFO_DATA_REQ |
+		I2C_INT_RX_FIFO_DATA_REQ);
+	i2c_writel(i2c_dev, status, I2C_INT_STATUS);
+	return IRQ_HANDLED;
+}
+
+static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
+	struct i2c_msg *msg, int stop)
+{
+	u32 packet_header;
+	u32 int_mask;
+	int ret;
+
+	tegra_i2c_flush_fifos(i2c_dev);
+	i2c_writel(i2c_dev, 0xFF, I2C_INT_STATUS);
+
+	if (msg->len == 0)
+		return -EINVAL;
+
+	i2c_dev->msg_buf = msg->buf;
+	i2c_dev->msg_buf_remaining = msg->len;
+	i2c_dev->msg_err = I2C_ERR_NONE;
+	i2c_dev->msg_read = (msg->flags & I2C_M_RD);
+	INIT_COMPLETION(i2c_dev->msg_complete);
+
+	packet_header = (0 << PACKET_HEADER0_HEADER_SIZE_SHIFT) |
+			PACKET_HEADER0_PROTOCOL_I2C |
+			(i2c_dev->cont_id << PACKET_HEADER0_CONT_ID_SHIFT) |
+			(1 << PACKET_HEADER0_PACKET_ID_SHIFT);
+	i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
+
+	packet_header = msg->len - 1;
+	i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
+
+	packet_header = msg->addr << I2C_HEADER_SLAVE_ADDR_SHIFT;
+	packet_header |= I2C_HEADER_IE_ENABLE;
+	if (msg->flags & I2C_M_TEN)
+		packet_header |= I2C_HEADER_10BIT_ADDR;
+	if (msg->flags & I2C_M_IGNORE_NAK)
+		packet_header |= I2C_HEADER_CONT_ON_NAK;
+	if (msg->flags & I2C_M_NOSTART)
+		packet_header |= I2C_HEADER_REPEAT_START;
+	if (msg->flags & I2C_M_RD)
+		packet_header |= I2C_HEADER_READ;
+	i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
+
+	if (!(msg->flags & I2C_M_RD))
+		tegra_i2c_fill_tx_fifo(i2c_dev);
+
+	int_mask = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
+	if (msg->flags & I2C_M_RD)
+		int_mask |= I2C_INT_RX_FIFO_DATA_REQ;
+	else if (i2c_dev->msg_buf_remaining)
+		int_mask |= I2C_INT_TX_FIFO_DATA_REQ;
+	tegra_i2c_unmask_irq(i2c_dev, int_mask);
+	dev_dbg(i2c_dev->dev, "unmasked irq: %02x\n",
+		i2c_readl(i2c_dev, I2C_INT_MASK));
+
+	ret = wait_for_completion_timeout(&i2c_dev->msg_complete, TEGRA_I2C_TIMEOUT);
+	tegra_i2c_mask_irq(i2c_dev, int_mask);
+
+	if (WARN_ON(ret == 0)) {
+		dev_err(i2c_dev->dev, "i2c transfer timed out\n");
+
+		tegra_i2c_init(i2c_dev);
+		return -ETIMEDOUT;
+	}
+
+	dev_dbg(i2c_dev->dev, "transfer complete: %d %d %d\n",
+		ret, completion_done(&i2c_dev->msg_complete), i2c_dev->msg_err);
+
+	if (likely(i2c_dev->msg_err == I2C_ERR_NONE))
+		return 0;
+
+	tegra_i2c_init(i2c_dev);
+	if (i2c_dev->msg_err == I2C_ERR_NO_ACK) {
+		if (msg->flags & I2C_M_IGNORE_NAK)
+			return 0;
+		return -EREMOTEIO;
+	}
+
+	return -EIO;
+}
+
+static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+	int num)
+{
+	struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+	int i;
+	int ret = 0;
+
+	if (i2c_dev->is_suspended)
+		return -EBUSY;
+
+	clk_enable(i2c_dev->clk);
+	for (i = 0; i < num; i++) {
+		int stop = (i == (num - 1)) ? 1  : 0;
+		ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], stop);
+		if (ret)
+			break;
+	}
+	clk_disable(i2c_dev->clk);
+	return ret ?: i;
+}
+
+static u32 tegra_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C;
+}
+
+static const struct i2c_algorithm tegra_i2c_algo = {
+	.master_xfer	= tegra_i2c_xfer,
+	.functionality	= tegra_i2c_func,
+};
+
+static int tegra_i2c_probe(struct platform_device *pdev)
+{
+	struct tegra_i2c_dev *i2c_dev;
+	struct tegra_i2c_platform_data *pdata = pdev->dev.platform_data;
+	struct resource *res;
+	struct resource *iomem;
+	struct clk *clk;
+	struct clk *i2c_clk;
+	void *base;
+	int irq;
+	int ret = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no mem resource\n");
+		return -EINVAL;
+	}
+	iomem = request_mem_region(res->start, resource_size(res), pdev->name);
+	if (!iomem) {
+		dev_err(&pdev->dev, "I2C region already claimed\n");
+		return -EBUSY;
+	}
+
+	base = ioremap(iomem->start, resource_size(iomem));
+	if (!base) {
+		dev_err(&pdev->dev, "Cannot ioremap I2C region\n");
+		return -ENOMEM;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no irq resource\n");
+		ret = -EINVAL;
+		goto err_iounmap;
+	}
+	irq = res->start;
+
+	clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "missing controller clock");
+		ret = PTR_ERR(clk);
+		goto err_release_region;
+	}
+
+	i2c_clk = clk_get(&pdev->dev, "i2c");
+	if (IS_ERR(i2c_clk)) {
+		dev_err(&pdev->dev, "missing bus clock");
+		ret = PTR_ERR(i2c_clk);
+		goto err_clk_put;
+	}
+
+	i2c_dev = kzalloc(sizeof(struct tegra_i2c_dev), GFP_KERNEL);
+	if (!i2c_dev) {
+		ret = -ENOMEM;
+		goto err_i2c_clk_put;
+	}
+
+	i2c_dev->base = base;
+	i2c_dev->clk = clk;
+	i2c_dev->i2c_clk = i2c_clk;
+	i2c_dev->iomem = iomem;
+	i2c_dev->adapter.algo = &tegra_i2c_algo;
+	i2c_dev->irq = irq;
+	i2c_dev->cont_id = pdev->id;
+	i2c_dev->dev = &pdev->dev;
+	i2c_dev->bus_clk_rate = pdata ? pdata->bus_clk_rate : 100000;
+
+	if (pdev->id == 3)
+		i2c_dev->is_dvc = 1;
+	init_completion(&i2c_dev->msg_complete);
+
+	platform_set_drvdata(pdev, i2c_dev);
+
+	ret = tegra_i2c_init(i2c_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to initialize i2c controller");
+		goto err_free;
+	}
+
+	ret = request_irq(i2c_dev->irq, tegra_i2c_isr, 0, pdev->name, i2c_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
+		goto err_free;
+	}
+
+	clk_enable(i2c_dev->i2c_clk);
+
+	i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
+	i2c_dev->adapter.owner = THIS_MODULE;
+	i2c_dev->adapter.class = I2C_CLASS_HWMON;
+	strlcpy(i2c_dev->adapter.name, "Tegra I2C adapter",
+		sizeof(i2c_dev->adapter.name));
+	i2c_dev->adapter.algo = &tegra_i2c_algo;
+	i2c_dev->adapter.dev.parent = &pdev->dev;
+	i2c_dev->adapter.nr = pdev->id;
+
+	ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add I2C adapter\n");
+		goto err_free_irq;
+	}
+
+	return 0;
+err_free_irq:
+	free_irq(i2c_dev->irq, i2c_dev);
+err_free:
+	kfree(i2c_dev);
+err_i2c_clk_put:
+	clk_put(i2c_clk);
+err_clk_put:
+	clk_put(clk);
+err_release_region:
+	release_mem_region(iomem->start, resource_size(iomem));
+err_iounmap:
+	iounmap(base);
+	return ret;
+}
+
+static int tegra_i2c_remove(struct platform_device *pdev)
+{
+	struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+	i2c_del_adapter(&i2c_dev->adapter);
+	free_irq(i2c_dev->irq, i2c_dev);
+	clk_put(i2c_dev->i2c_clk);
+	clk_put(i2c_dev->clk);
+	release_mem_region(i2c_dev->iomem->start,
+		resource_size(i2c_dev->iomem));
+	iounmap(i2c_dev->base);
+	kfree(i2c_dev);
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int tegra_i2c_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+	i2c_lock_adapter(&i2c_dev->adapter);
+	i2c_dev->is_suspended = true;
+	i2c_unlock_adapter(&i2c_dev->adapter);
+
+	return 0;
+}
+
+static int tegra_i2c_resume(struct platform_device *pdev)
+{
+	struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+	int ret;
+
+	i2c_lock_adapter(&i2c_dev->adapter);
+
+	ret = tegra_i2c_init(i2c_dev);
+
+	if (ret) {
+		i2c_unlock_adapter(&i2c_dev->adapter);
+		return ret;
+	}
+
+	i2c_dev->is_suspended = false;
+
+	i2c_unlock_adapter(&i2c_dev->adapter);
+
+	return 0;
+}
+#endif
+
+static struct platform_driver tegra_i2c_driver = {
+	.probe   = tegra_i2c_probe,
+	.remove  = tegra_i2c_remove,
+#ifdef CONFIG_PM
+	.suspend = tegra_i2c_suspend,
+	.resume  = tegra_i2c_resume,
+#endif
+	.driver  = {
+		.name  = "tegra-i2c",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init tegra_i2c_init_driver(void)
+{
+	return platform_driver_register(&tegra_i2c_driver);
+}
+
+static void __exit tegra_i2c_exit_driver(void)
+{
+	platform_driver_unregister(&tegra_i2c_driver);
+}
+
+subsys_initcall(tegra_i2c_init_driver);
+module_exit(tegra_i2c_exit_driver);
+
+MODULE_DESCRIPTION("nVidia Tegra2 I2C Bus Controller driver");
+MODULE_AUTHOR("Colin Cross");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/i2c-tegra.h b/include/linux/i2c-tegra.h
new file mode 100644
index 0000000..9c85da4
--- /dev/null
+++ b/include/linux/i2c-tegra.h
@@ -0,0 +1,25 @@
+/*
+ * drivers/i2c/busses/i2c-tegra.c
+ *
+ * Copyright (C) 2010 Google, Inc.
+ * Author: Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _LINUX_I2C_TEGRA_H
+#define _LINUX_I2C_TEGRA_H
+
+struct tegra_i2c_platform_data {
+	unsigned long bus_clk_rate;
+};
+
+#endif /* _LINUX_I2C_TEGRA_H */
-- 
1.7.3.1