i2c: img-scb: Add Imagination Technologies I2C SCB driver

Add support for the IMG I2C Serial Control Bus (SCB) found on the
Pistachio and TZ1090 SoCs.

Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
[Ezequiel: code cleaning and rebasing]
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

3 files changed, 1423 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 06e99eb64295..03c6119325ef 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -524,6 +524,16 @@ config I2C_IBM_IIC
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-ibm_iic.
 
+config I2C_IMG
+	tristate "Imagination Technologies I2C SCB Controller"
+	depends on SOC_TZ1090 || COMPILE_TEST
+	help
+	  Say Y here if you want to use the IMG I2C SCB controller,
+	  available on the TZ1090 SoC.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-img-scb.
+
 config I2C_IMX
 	tristate "IMX I2C interface"
 	depends on ARCH_MXC
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 78d56c54ba2b..84861ead6be9 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
 obj-$(CONFIG_I2C_HIGHLANDER)	+= i2c-highlander.o
 obj-$(CONFIG_I2C_HIX5HD2)	+= i2c-hix5hd2.o
 obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
+obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
new file mode 100644
index 000000000000..0fcc1694c607
--- /dev/null
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -0,0 +1,1412 @@
+/*
+ * I2C adapter for the IMG Serial Control Bus (SCB) IP block.
+ *
+ * Copyright (C) 2009, 2010, 2012, 2014 Imagination Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * There are three ways that this I2C controller can be driven:
+ *
+ * - Raw control of the SDA and SCK signals.
+ *
+ *   This corresponds to MODE_RAW, which takes control of the signals
+ *   directly for a certain number of clock cycles (the INT_TIMING
+ *   interrupt can be used for timing).
+ *
+ * - Atomic commands. A low level I2C symbol (such as generate
+ *   start/stop/ack/nack bit, generate byte, receive byte, and receive
+ *   ACK) is given to the hardware, with detection of completion by bits
+ *   in the LINESTAT register.
+ *
+ *   This mode of operation is used by MODE_ATOMIC, which uses an I2C
+ *   state machine in the interrupt handler to compose/react to I2C
+ *   transactions using atomic mode commands, and also by MODE_SEQUENCE,
+ *   which emits a simple fixed sequence of atomic mode commands.
+ *
+ *   Due to software control, the use of atomic commands usually results
+ *   in suboptimal use of the bus, with gaps between the I2C symbols while
+ *   the driver decides what to do next.
+ *
+ * - Automatic mode. A bus address, and whether to read/write is
+ *   specified, and the hardware takes care of the I2C state machine,
+ *   using a FIFO to send/receive bytes of data to an I2C slave. The
+ *   driver just has to keep the FIFO drained or filled in response to the
+ *   appropriate FIFO interrupts.
+ *
+ *   This corresponds to MODE_AUTOMATIC, which manages the FIFOs and deals
+ *   with control of repeated start bits between I2C messages.
+ *
+ *   Use of automatic mode and the FIFO can make much more efficient use
+ *   of the bus compared to individual atomic commands, with potentially
+ *   no wasted time between I2C symbols or I2C messages.
+ *
+ * In most cases MODE_AUTOMATIC is used, however if any of the messages in
+ * a transaction are zero byte writes (e.g. used by i2cdetect for probing
+ * the bus), MODE_ATOMIC must be used since automatic mode is normally
+ * started by the writing of data into the FIFO.
+ *
+ * The other modes are used in specific circumstances where MODE_ATOMIC and
+ * MODE_AUTOMATIC aren't appropriate. MODE_RAW is used to implement a bus
+ * recovery routine. MODE_SEQUENCE is used to reset the bus and make sure
+ * it is in a sane state.
+ *
+ * Notice that the driver implements a timer-based timeout mechanism.
+ * The reason for this mechanism is to reduce the number of interrupts
+ * received in automatic mode.
+ *
+ * The driver would get a slave event and transaction done interrupts for
+ * each atomic mode command that gets completed. However, these events are
+ * not needed in automatic mode, becase those atomic mode commands are
+ * managed automatically by the hardware.
+ *
+ * In practice, normal I2C transactions will be complete well before you
+ * get the timer interrupt, as the timer is re-scheduled during FIFO
+ * maintenance and disabled after the transaction is complete.
+ *
+ * In this way normal automatic mode operation isn't impacted by
+ * unnecessary interrupts, but the exceptional abort condition can still be
+ * detected (with a slight delay).
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+
+/* Register offsets */
+
+#define SCB_STATUS_REG			0x00
+#define SCB_OVERRIDE_REG		0x04
+#define SCB_READ_ADDR_REG		0x08
+#define SCB_READ_COUNT_REG		0x0c
+#define SCB_WRITE_ADDR_REG		0x10
+#define SCB_READ_DATA_REG		0x14
+#define SCB_WRITE_DATA_REG		0x18
+#define SCB_FIFO_STATUS_REG		0x1c
+#define SCB_CONTROL_SOFT_RESET		0x1f
+#define SCB_CLK_SET_REG			0x3c
+#define SCB_INT_STATUS_REG		0x40
+#define SCB_INT_CLEAR_REG		0x44
+#define SCB_INT_MASK_REG		0x48
+#define SCB_CONTROL_REG			0x4c
+#define SCB_TIME_TPL_REG		0x50
+#define SCB_TIME_TPH_REG		0x54
+#define SCB_TIME_TP2S_REG		0x58
+#define SCB_TIME_TBI_REG		0x60
+#define SCB_TIME_TSL_REG		0x64
+#define SCB_TIME_TDL_REG		0x68
+#define SCB_TIME_TSDL_REG		0x6c
+#define SCB_TIME_TSDH_REG		0x70
+#define SCB_READ_XADDR_REG		0x74
+#define SCB_WRITE_XADDR_REG		0x78
+#define SCB_WRITE_COUNT_REG		0x7c
+#define SCB_CORE_REV_REG		0x80
+#define SCB_TIME_TCKH_REG		0x84
+#define SCB_TIME_TCKL_REG		0x88
+#define SCB_FIFO_FLUSH_REG		0x8c
+#define SCB_READ_FIFO_REG		0x94
+#define SCB_CLEAR_REG			0x98
+
+/* SCB_CONTROL_REG bits */
+
+#define SCB_CONTROL_CLK_ENABLE		0x1e0
+#define SCB_CONTROL_TRANSACTION_HALT	0x200
+
+#define FIFO_READ_FULL			BIT(0)
+#define FIFO_READ_EMPTY			BIT(1)
+#define FIFO_WRITE_FULL			BIT(2)
+#define FIFO_WRITE_EMPTY		BIT(3)
+
+/* SCB_CLK_SET_REG bits */
+#define SCB_FILT_DISABLE		BIT(31)
+#define SCB_FILT_BYPASS			BIT(30)
+#define SCB_FILT_INC_MASK		0x7f
+#define SCB_FILT_INC_SHIFT		16
+#define SCB_INC_MASK			0x7f
+#define SCB_INC_SHIFT			8
+
+/* SCB_INT_*_REG bits */
+
+#define INT_BUS_INACTIVE		BIT(0)
+#define INT_UNEXPECTED_START		BIT(1)
+#define INT_SCLK_LOW_TIMEOUT		BIT(2)
+#define INT_SDAT_LOW_TIMEOUT		BIT(3)
+#define INT_WRITE_ACK_ERR		BIT(4)
+#define INT_ADDR_ACK_ERR		BIT(5)
+#define INT_FIFO_FULL			BIT(9)
+#define INT_FIFO_FILLING		BIT(10)
+#define INT_FIFO_EMPTY			BIT(11)
+#define INT_FIFO_EMPTYING		BIT(12)
+#define INT_TRANSACTION_DONE		BIT(15)
+#define INT_SLAVE_EVENT			BIT(16)
+#define INT_TIMING			BIT(18)
+
+#define INT_FIFO_FULL_FILLING	(INT_FIFO_FULL  | INT_FIFO_FILLING)
+#define INT_FIFO_EMPTY_EMPTYING	(INT_FIFO_EMPTY | INT_FIFO_EMPTYING)
+
+/* Level interrupts need clearing after handling instead of before */
+#define INT_LEVEL			0x01e00
+
+/* Don't allow any interrupts while the clock may be off */
+#define INT_ENABLE_MASK_INACTIVE	0x00000
+
+/* Interrupt masks for the different driver modes */
+
+#define INT_ENABLE_MASK_RAW		INT_TIMING
+
+#define INT_ENABLE_MASK_ATOMIC		(INT_TRANSACTION_DONE | \
+					 INT_SLAVE_EVENT      | \
+					 INT_ADDR_ACK_ERR     | \
+					 INT_WRITE_ACK_ERR)
+
+#define INT_ENABLE_MASK_AUTOMATIC	(INT_SCLK_LOW_TIMEOUT | \
+					 INT_ADDR_ACK_ERR     | \
+					 INT_WRITE_ACK_ERR    | \
+					 INT_FIFO_FULL        | \
+					 INT_FIFO_FILLING     | \
+					 INT_FIFO_EMPTY       | \
+					 INT_FIFO_EMPTYING)
+
+#define INT_ENABLE_MASK_WAITSTOP	(INT_SLAVE_EVENT      | \
+					 INT_ADDR_ACK_ERR     | \
+					 INT_WRITE_ACK_ERR)
+
+/* SCB_STATUS_REG fields */
+
+#define LINESTAT_SCLK_LINE_STATUS	BIT(0)
+#define LINESTAT_SCLK_EN		BIT(1)
+#define LINESTAT_SDAT_LINE_STATUS	BIT(2)
+#define LINESTAT_SDAT_EN		BIT(3)
+#define LINESTAT_DET_START_STATUS	BIT(4)
+#define LINESTAT_DET_STOP_STATUS	BIT(5)
+#define LINESTAT_DET_ACK_STATUS		BIT(6)
+#define LINESTAT_DET_NACK_STATUS	BIT(7)
+#define LINESTAT_BUS_IDLE		BIT(8)
+#define LINESTAT_T_DONE_STATUS		BIT(9)
+#define LINESTAT_SCLK_OUT_STATUS	BIT(10)
+#define LINESTAT_SDAT_OUT_STATUS	BIT(11)
+#define LINESTAT_GEN_LINE_MASK_STATUS	BIT(12)
+#define LINESTAT_START_BIT_DET		BIT(13)
+#define LINESTAT_STOP_BIT_DET		BIT(14)
+#define LINESTAT_ACK_DET		BIT(15)
+#define LINESTAT_NACK_DET		BIT(16)
+#define LINESTAT_INPUT_HELD_V		BIT(17)
+#define LINESTAT_ABORT_DET		BIT(18)
+#define LINESTAT_ACK_OR_NACK_DET	(LINESTAT_ACK_DET | LINESTAT_NACK_DET)
+#define LINESTAT_INPUT_DATA		0xff000000
+#define LINESTAT_INPUT_DATA_SHIFT	24
+
+#define LINESTAT_CLEAR_SHIFT		13
+#define LINESTAT_LATCHED		(0x3f << LINESTAT_CLEAR_SHIFT)
+
+/* SCB_OVERRIDE_REG fields */
+
+#define OVERRIDE_SCLK_OVR		BIT(0)
+#define OVERRIDE_SCLKEN_OVR		BIT(1)
+#define OVERRIDE_SDAT_OVR		BIT(2)
+#define OVERRIDE_SDATEN_OVR		BIT(3)
+#define OVERRIDE_MASTER			BIT(9)
+#define OVERRIDE_LINE_OVR_EN		BIT(10)
+#define OVERRIDE_DIRECT			BIT(11)
+#define OVERRIDE_CMD_SHIFT		4
+#define OVERRIDE_CMD_MASK		0x1f
+#define OVERRIDE_DATA_SHIFT		24
+
+#define OVERRIDE_SCLK_DOWN		(OVERRIDE_LINE_OVR_EN | \
+					 OVERRIDE_SCLKEN_OVR)
+#define OVERRIDE_SCLK_UP		(OVERRIDE_LINE_OVR_EN | \
+					 OVERRIDE_SCLKEN_OVR | \
+					 OVERRIDE_SCLK_OVR)
+#define OVERRIDE_SDAT_DOWN		(OVERRIDE_LINE_OVR_EN | \
+					 OVERRIDE_SDATEN_OVR)
+#define OVERRIDE_SDAT_UP		(OVERRIDE_LINE_OVR_EN | \
+					 OVERRIDE_SDATEN_OVR | \
+					 OVERRIDE_SDAT_OVR)
+
+/* OVERRIDE_CMD values */
+
+#define CMD_PAUSE			0x00
+#define CMD_GEN_DATA			0x01
+#define CMD_GEN_START			0x02
+#define CMD_GEN_STOP			0x03
+#define CMD_GEN_ACK			0x04
+#define CMD_GEN_NACK			0x05
+#define CMD_RET_DATA			0x08
+#define CMD_RET_ACK			0x09
+
+/* Fixed timing values */
+
+#define TIMEOUT_TBI			0x0
+#define TIMEOUT_TSL			0xffff
+#define TIMEOUT_TDL			0x0
+
+/* Transaction timeout */
+
+#define IMG_I2C_TIMEOUT			(msecs_to_jiffies(1000))
+
+/*
+ * Worst incs are 1 (innacurate) and 16*256 (irregular).
+ * So a sensible inc is the logarithmic mean: 64 (2^6), which is
+ * in the middle of the valid range (0-127).
+ */
+#define SCB_OPT_INC		64
+
+/* Setup the clock enable filtering for 25 ns */
+#define SCB_FILT_GLITCH		25
+
+/*
+ * Bits to return from interrupt handler functions for different modes.
+ * This delays completion until we've finished with the registers, so that the
+ * function waiting for completion can safely disable the clock to save power.
+ */
+#define ISR_COMPLETE_M		BIT(31)
+#define ISR_FATAL_M		BIT(30)
+#define ISR_WAITSTOP		BIT(29)
+#define ISR_STATUS_M		0x0000ffff	/* contains +ve errno */
+#define ISR_COMPLETE(err)	(ISR_COMPLETE_M | (ISR_STATUS_M & (err)))
+#define ISR_FATAL(err)		(ISR_COMPLETE(err) | ISR_FATAL_M)
+
+#define REL_SOC_IP_SCB_2_2_1	0x00020201
+
+enum img_i2c_mode {
+	MODE_INACTIVE,
+	MODE_RAW,
+	MODE_ATOMIC,
+	MODE_AUTOMATIC,
+	MODE_SEQUENCE,
+	MODE_FATAL,
+	MODE_WAITSTOP,
+	MODE_SUSPEND,
+};
+
+/* Timing parameters for i2c modes (in ns) */
+struct img_i2c_timings {
+	const char *name;
+	unsigned int max_bitrate;
+	unsigned int tckh, tckl, tsdh, tsdl;
+	unsigned int tp2s, tpl, tph;
+};
+
+/* The timings array must be ordered from slower to faster */
+static struct img_i2c_timings timings[] = {
+	/* Standard mode */
+	{
+		.name = "standard",
+		.max_bitrate = 100000,
+		.tckh = 4000,
+		.tckl = 4700,
+		.tsdh = 4700,
+		.tsdl = 8700,
+		.tp2s = 4700,
+		.tpl = 4700,
+		.tph = 4000,
+	},
+	/* Fast mode */
+	{
+		.name = "fast",
+		.max_bitrate = 400000,
+		.tckh = 600,
+		.tckl = 1300,
+		.tsdh = 600,
+		.tsdl = 1200,
+		.tp2s = 1300,
+		.tpl = 600,
+		.tph = 600,
+	},
+};
+
+/* Reset dance */
+static u8 img_i2c_reset_seq[] = { CMD_GEN_START,
+				  CMD_GEN_DATA, 0xff,
+				  CMD_RET_ACK,
+				  CMD_GEN_START,
+				  CMD_GEN_STOP,
+				  0 };
+/* Just issue a stop (after an abort condition) */
+static u8 img_i2c_stop_seq[] = {  CMD_GEN_STOP,
+				  0 };
+
+/* We're interested in different interrupts depending on the mode */
+static unsigned int img_i2c_int_enable_by_mode[] = {
+	[MODE_INACTIVE]  = INT_ENABLE_MASK_INACTIVE,
+	[MODE_RAW]       = INT_ENABLE_MASK_RAW,
+	[MODE_ATOMIC]    = INT_ENABLE_MASK_ATOMIC,
+	[MODE_AUTOMATIC] = INT_ENABLE_MASK_AUTOMATIC,
+	[MODE_SEQUENCE]  = INT_ENABLE_MASK_ATOMIC,
+	[MODE_FATAL]     = 0,
+	[MODE_WAITSTOP]  = INT_ENABLE_MASK_WAITSTOP,
+	[MODE_SUSPEND]   = 0,
+};
+
+/* Atomic command names */
+static const char * const img_i2c_atomic_cmd_names[] = {
+	[CMD_PAUSE]	= "PAUSE",
+	[CMD_GEN_DATA]	= "GEN_DATA",
+	[CMD_GEN_START]	= "GEN_START",
+	[CMD_GEN_STOP]	= "GEN_STOP",
+	[CMD_GEN_ACK]	= "GEN_ACK",
+	[CMD_GEN_NACK]	= "GEN_NACK",
+	[CMD_RET_DATA]	= "RET_DATA",
+	[CMD_RET_ACK]	= "RET_ACK",
+};
+
+struct img_i2c {
+	struct i2c_adapter adap;
+
+	void __iomem *base;
+
+	/*
+	 * The scb core clock is used to get the input frequency, and to disable
+	 * it after every set of transactions to save some power.
+	 */
+	struct clk *scb_clk, *sys_clk;
+	unsigned int bitrate;
+	bool need_wr_rd_fence;
+
+	/* state */
+	struct completion msg_complete;
+	spinlock_t lock;	/* lock before doing anything with the state */
+	struct i2c_msg msg;
+
+	/* After the last transaction, wait for a stop bit */
+	bool last_msg;
+	int msg_status;
+
+	enum img_i2c_mode mode;
+	u32 int_enable;		/* depends on mode */
+	u32 line_status;	/* line status over command */
+
+	/*
+	 * To avoid slave event interrupts in automatic mode, use a timer to
+	 * poll the abort condition if we don't get an interrupt for too long.
+	 */
+	struct timer_list check_timer;
+	bool t_halt;
+
+	/* atomic mode state */
+	bool at_t_done;
+	bool at_slave_event;
+	int at_cur_cmd;
+	u8 at_cur_data;
+
+	/* Sequence: either reset or stop. See img_i2c_sequence. */
+	u8 *seq;
+
+	/* raw mode */
+	unsigned int raw_timeout;
+};
+
+static void img_i2c_writel(struct img_i2c *i2c, u32 offset, u32 value)
+{
+	writel(value, i2c->base + offset);
+}
+
+static u32 img_i2c_readl(struct img_i2c *i2c, u32 offset)
+{
+	return readl(i2c->base + offset);
+}
+
+/*
+ * The code to read from the master read fifo, and write to the master
+ * write fifo, checks a bit in an SCB register before every byte to
+ * ensure that the fifo is not full (write fifo) or empty (read fifo).
+ * Due to clock domain crossing inside the SCB block the updated value
+ * of this bit is only visible after 2 cycles.
+ *
+ * The scb_wr_rd_fence() function does 2 dummy writes (to the read-only
+ * revision register), and it's called after reading from or writing to the
+ * fifos to ensure that subsequent reads of the fifo status bits do not read
+ * stale values.
+ */
+static void img_i2c_wr_rd_fence(struct img_i2c *i2c)
+{
+	if (i2c->need_wr_rd_fence) {
+		img_i2c_writel(i2c, SCB_CORE_REV_REG, 0);
+		img_i2c_writel(i2c, SCB_CORE_REV_REG, 0);
+	}
+}
+
+static void img_i2c_switch_mode(struct img_i2c *i2c, enum img_i2c_mode mode)
+{
+	i2c->mode = mode;
+	i2c->int_enable = img_i2c_int_enable_by_mode[mode];
+	i2c->line_status = 0;
+}
+
+static void img_i2c_raw_op(struct img_i2c *i2c)
+{
+	i2c->raw_timeout = 0;
+	img_i2c_writel(i2c, SCB_OVERRIDE_REG,
+		OVERRIDE_SCLKEN_OVR |
+		OVERRIDE_SDATEN_OVR |
+		OVERRIDE_MASTER |
+		OVERRIDE_LINE_OVR_EN |
+		OVERRIDE_DIRECT |
+		((i2c->at_cur_cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) |
+		(i2c->at_cur_data << OVERRIDE_DATA_SHIFT));
+}
+
+static const char *img_i2c_atomic_op_name(unsigned int cmd)
+{
+	if (unlikely(cmd >= ARRAY_SIZE(img_i2c_atomic_cmd_names)))
+		return "UNKNOWN";
+	return img_i2c_atomic_cmd_names[cmd];
+}
+
+/* Send a single atomic mode command to the hardware */
+static void img_i2c_atomic_op(struct img_i2c *i2c, int cmd, u8 data)
+{
+	i2c->at_cur_cmd = cmd;
+	i2c->at_cur_data = data;
+
+	/* work around lack of data setup time when generating data */
+	if (cmd == CMD_GEN_DATA && i2c->mode == MODE_ATOMIC) {
+		u32 line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
+
+		if (line_status & LINESTAT_SDAT_LINE_STATUS && !(data & 0x80)) {
+			/* hold the data line down for a moment */
+			img_i2c_switch_mode(i2c, MODE_RAW);
+			img_i2c_raw_op(i2c);
+			return;
+		}
+	}
+
+	dev_dbg(i2c->adap.dev.parent,
+		"atomic cmd=%s (%d) data=%#x\n",
+		img_i2c_atomic_op_name(cmd), cmd, data);
+	i2c->at_t_done = (cmd == CMD_RET_DATA || cmd == CMD_RET_ACK);
+	i2c->at_slave_event = false;
+	i2c->line_status = 0;
+
+	img_i2c_writel(i2c, SCB_OVERRIDE_REG,
+		((cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) |
+		OVERRIDE_MASTER |
+		OVERRIDE_DIRECT |
+		(data << OVERRIDE_DATA_SHIFT));
+}
+
+/* Start a transaction in atomic mode */
+static void img_i2c_atomic_start(struct img_i2c *i2c)
+{
+	img_i2c_switch_mode(i2c, MODE_ATOMIC);
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+	img_i2c_atomic_op(i2c, CMD_GEN_START, 0x00);
+}
+
+static void img_i2c_soft_reset(struct img_i2c *i2c)
+{
+	i2c->t_halt = false;
+	img_i2c_writel(i2c, SCB_CONTROL_REG, 0);
+	img_i2c_writel(i2c, SCB_CONTROL_REG,
+		       SCB_CONTROL_CLK_ENABLE | SCB_CONTROL_SOFT_RESET);
+}
+
+/* enable or release transaction halt for control of repeated starts */
+static void img_i2c_transaction_halt(struct img_i2c *i2c, bool t_halt)
+{
+	u32 val;
+
+	if (i2c->t_halt == t_halt)
+		return;
+	i2c->t_halt = t_halt;
+	val = img_i2c_readl(i2c, SCB_CONTROL_REG);
+	if (t_halt)
+		val |= SCB_CONTROL_TRANSACTION_HALT;
+	else
+		val &= ~SCB_CONTROL_TRANSACTION_HALT;
+	img_i2c_writel(i2c, SCB_CONTROL_REG, val);
+}
+
+/* Drain data from the FIFO into the buffer (automatic mode) */
+static void img_i2c_read_fifo(struct img_i2c *i2c)
+{
+	while (i2c->msg.len) {
+		u32 fifo_status;
+		u8 data;
+
+		fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
+		if (fifo_status & FIFO_READ_EMPTY)
+			break;
+
+		data = img_i2c_readl(i2c, SCB_READ_DATA_REG);
+		*i2c->msg.buf = data;
+
+		img_i2c_writel(i2c, SCB_READ_FIFO_REG, 0xff);
+		img_i2c_wr_rd_fence(i2c);
+		i2c->msg.len--;
+		i2c->msg.buf++;
+	}
+}
+
+/* Fill the FIFO with data from the buffer (automatic mode) */
+static void img_i2c_write_fifo(struct img_i2c *i2c)
+{
+	while (i2c->msg.len) {
+		u32 fifo_status;
+
+		fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
+		if (fifo_status & FIFO_WRITE_FULL)
+			break;
+
+		img_i2c_writel(i2c, SCB_WRITE_DATA_REG, *i2c->msg.buf);
+		img_i2c_wr_rd_fence(i2c);
+		i2c->msg.len--;
+		i2c->msg.buf++;
+	}
+
+	/* Disable fifo emptying interrupt if nothing more to write */
+	if (!i2c->msg.len)
+		i2c->int_enable &= ~INT_FIFO_EMPTYING;
+}
+
+/* Start a read transaction in automatic mode */
+static void img_i2c_read(struct img_i2c *i2c)
+{
+	img_i2c_switch_mode(i2c, MODE_AUTOMATIC);
+	if (!i2c->last_msg)
+		i2c->int_enable |= INT_SLAVE_EVENT;
+
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+	img_i2c_writel(i2c, SCB_READ_ADDR_REG, i2c->msg.addr);
+	img_i2c_writel(i2c, SCB_READ_COUNT_REG, i2c->msg.len);
+
+	img_i2c_transaction_halt(i2c, false);
+	mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
+}
+
+/* Start a write transaction in automatic mode */
+static void img_i2c_write(struct img_i2c *i2c)
+{
+	img_i2c_switch_mode(i2c, MODE_AUTOMATIC);
+	if (!i2c->last_msg)
+		i2c->int_enable |= INT_SLAVE_EVENT;
+
+	img_i2c_writel(i2c, SCB_WRITE_ADDR_REG, i2c->msg.addr);
+	img_i2c_writel(i2c, SCB_WRITE_COUNT_REG, i2c->msg.len);
+
+	img_i2c_transaction_halt(i2c, false);
+	mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
+	img_i2c_write_fifo(i2c);
+
+	/* img_i2c_write_fifo() may modify int_enable */
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+}
+
+/*
+ * Indicate that the transaction is complete. This is called from the
+ * ISR to wake up the waiting thread, after which the ISR must not
+ * access any more SCB registers.
+ */
+static void img_i2c_complete_transaction(struct img_i2c *i2c, int status)
+{
+	img_i2c_switch_mode(i2c, MODE_INACTIVE);
+	if (status) {
+		i2c->msg_status = status;
+		img_i2c_transaction_halt(i2c, false);
+	}
+	complete(&i2c->msg_complete);
+}
+
+static unsigned int img_i2c_raw_atomic_delay_handler(struct img_i2c *i2c,
+					u32 int_status, u32 line_status)
+{
+	/* Stay in raw mode for this, so we don't just loop infinitely */
+	img_i2c_atomic_op(i2c, i2c->at_cur_cmd, i2c->at_cur_data);
+	img_i2c_switch_mode(i2c, MODE_ATOMIC);
+	return 0;
+}
+
+static unsigned int img_i2c_raw(struct img_i2c *i2c, u32 int_status,
+				u32 line_status)
+{
+	if (int_status & INT_TIMING) {
+		if (i2c->raw_timeout == 0)
+			return img_i2c_raw_atomic_delay_handler(i2c,
+				int_status, line_status);
+		--i2c->raw_timeout;
+	}
+	return 0;
+}
+
+static unsigned int img_i2c_sequence(struct img_i2c *i2c, u32 int_status)
+{
+	static const unsigned int continue_bits[] = {
+		[CMD_GEN_START] = LINESTAT_START_BIT_DET,
+		[CMD_GEN_DATA]  = LINESTAT_INPUT_HELD_V,
+		[CMD_RET_ACK]   = LINESTAT_ACK_DET | LINESTAT_NACK_DET,
+		[CMD_RET_DATA]  = LINESTAT_INPUT_HELD_V,
+		[CMD_GEN_STOP]  = LINESTAT_STOP_BIT_DET,
+	};
+	int next_cmd = -1;
+	u8 next_data = 0x00;
+
+	if (int_status & INT_SLAVE_EVENT)
+		i2c->at_slave_event = true;
+	if (int_status & INT_TRANSACTION_DONE)
+		i2c->at_t_done = true;
+
+	if (!i2c->at_slave_event || !i2c->at_t_done)
+		return 0;
+
+	/* wait if no continue bits are set */
+	if (i2c->at_cur_cmd >= 0 &&
+	    i2c->at_cur_cmd < ARRAY_SIZE(continue_bits)) {
+		unsigned int cont_bits = continue_bits[i2c->at_cur_cmd];
+
+		if (cont_bits) {
+			cont_bits |= LINESTAT_ABORT_DET;
+			if (!(i2c->line_status & cont_bits))
+				return 0;
+		}
+	}
+
+	/* follow the sequence of commands in i2c->seq */
+	next_cmd = *i2c->seq;
+	/* stop on a nil */
+	if (!next_cmd) {
+		img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0);
+		return ISR_COMPLETE(0);
+	}
+	/* when generating data, the next byte is the data */
+	if (next_cmd == CMD_GEN_DATA) {
+		++i2c->seq;
+		next_data = *i2c->seq;
+	}
+	++i2c->seq;
+	img_i2c_atomic_op(i2c, next_cmd, next_data);
+
+	return 0;
+}
+
+static void img_i2c_reset_start(struct img_i2c *i2c)
+{
+	/* Initiate the magic dance */
+	img_i2c_switch_mode(i2c, MODE_SEQUENCE);
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+	i2c->seq = img_i2c_reset_seq;
+	i2c->at_slave_event = true;
+	i2c->at_t_done = true;
+	i2c->at_cur_cmd = -1;
+
+	/* img_i2c_reset_seq isn't empty so the following won't fail */
+	img_i2c_sequence(i2c, 0);
+}
+
+static void img_i2c_stop_start(struct img_i2c *i2c)
+{
+	/* Initiate a stop bit sequence */
+	img_i2c_switch_mode(i2c, MODE_SEQUENCE);
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+	i2c->seq = img_i2c_stop_seq;
+	i2c->at_slave_event = true;
+	i2c->at_t_done = true;
+	i2c->at_cur_cmd = -1;
+
+	/* img_i2c_stop_seq isn't empty so the following won't fail */
+	img_i2c_sequence(i2c, 0);
+}
+
+static unsigned int img_i2c_atomic(struct img_i2c *i2c,
+				   u32 int_status,
+				   u32 line_status)
+{
+	int next_cmd = -1;
+	u8 next_data = 0x00;
+
+	if (int_status & INT_SLAVE_EVENT)
+		i2c->at_slave_event = true;
+	if (int_status & INT_TRANSACTION_DONE)
+		i2c->at_t_done = true;
+
+	if (!i2c->at_slave_event || !i2c->at_t_done)
+		goto next_atomic_cmd;
+	if (i2c->line_status & LINESTAT_ABORT_DET) {
+		dev_dbg(i2c->adap.dev.parent, "abort condition detected\n");
+		next_cmd = CMD_GEN_STOP;
+		i2c->msg_status = -EIO;
+		goto next_atomic_cmd;
+	}
+
+	/* i2c->at_cur_cmd may have completed */
+	switch (i2c->at_cur_cmd) {
+	case CMD_GEN_START:
+		next_cmd = CMD_GEN_DATA;
+		next_data = (i2c->msg.addr << 1);
+		if (i2c->msg.flags & I2C_M_RD)
+			next_data |= 0x1;
+		break;
+	case CMD_GEN_DATA:
+		if (i2c->line_status & LINESTAT_INPUT_HELD_V)
+			next_cmd = CMD_RET_ACK;
+		break;
+	case CMD_RET_ACK:
+		if (i2c->line_status & LINESTAT_ACK_DET) {
+			if (i2c->msg.len == 0) {
+				next_cmd = CMD_GEN_STOP;
+			} else if (i2c->msg.flags & I2C_M_RD) {
+				next_cmd = CMD_RET_DATA;
+			} else {
+				next_cmd = CMD_GEN_DATA;
+				next_data = *i2c->msg.buf;
+				--i2c->msg.len;
+				++i2c->msg.buf;
+			}
+		} else if (i2c->line_status & LINESTAT_NACK_DET) {
+			i2c->msg_status = -EIO;
+			next_cmd = CMD_GEN_STOP;
+		}
+		break;
+	case CMD_RET_DATA:
+		if (i2c->line_status & LINESTAT_INPUT_HELD_V) {
+			*i2c->msg.buf = (i2c->line_status &
+						LINESTAT_INPUT_DATA)
+					>> LINESTAT_INPUT_DATA_SHIFT;
+			--i2c->msg.len;
+			++i2c->msg.buf;
+			if (i2c->msg.len)
+				next_cmd = CMD_GEN_ACK;
+			else
+				next_cmd = CMD_GEN_NACK;
+		}
+		break;
+	case CMD_GEN_ACK:
+		if (i2c->line_status & LINESTAT_ACK_DET) {
+			next_cmd = CMD_RET_DATA;
+		} else {
+			i2c->msg_status = -EIO;
+			next_cmd = CMD_GEN_STOP;
+		}
+		break;
+	case CMD_GEN_NACK:
+		next_cmd = CMD_GEN_STOP;
+		break;
+	case CMD_GEN_STOP:
+		img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0);
+		return ISR_COMPLETE(0);
+	default:
+		dev_err(i2c->adap.dev.parent, "bad atomic command %d\n",
+			i2c->at_cur_cmd);
+		i2c->msg_status = -EIO;
+		next_cmd = CMD_GEN_STOP;
+		break;
+	}
+
+next_atomic_cmd:
+	if (next_cmd != -1) {
+		/* don't actually stop unless we're the last transaction */
+		if (next_cmd == CMD_GEN_STOP && !i2c->msg_status &&
+						!i2c->last_msg)
+			return ISR_COMPLETE(0);
+		img_i2c_atomic_op(i2c, next_cmd, next_data);
+	}
+	return 0;
+}
+
+/*
+ * Timer function to check if something has gone wrong in automatic mode (so we
+ * don't have to handle so many interrupts just to catch an exception).
+ */
+static void img_i2c_check_timer(unsigned long arg)
+{
+	struct img_i2c *i2c = (struct img_i2c *)arg;
+	unsigned long flags;
+	unsigned int line_status;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+	line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
+
+	/* check for an abort condition */
+	if (line_status & LINESTAT_ABORT_DET) {
+		dev_dbg(i2c->adap.dev.parent,
+			"abort condition detected by check timer\n");
+		/* enable slave event interrupt mask to trigger irq */
+		img_i2c_writel(i2c, SCB_INT_MASK_REG,
+			       i2c->int_enable | INT_SLAVE_EVENT);
+	}
+
+	spin_unlock_irqrestore(&i2c->lock, flags);
+}
+
+static unsigned int img_i2c_auto(struct img_i2c *i2c,
+				 unsigned int int_status,
+				 unsigned int line_status)
+{
+	if (int_status & (INT_WRITE_ACK_ERR | INT_ADDR_ACK_ERR))
+		return ISR_COMPLETE(EIO);
+
+	if (line_status & LINESTAT_ABORT_DET) {
+		dev_dbg(i2c->adap.dev.parent, "abort condition detected\n");
+		/* empty the read fifo */
+		if ((i2c->msg.flags & I2C_M_RD) &&
+		    (int_status & INT_FIFO_FULL_FILLING))
+			img_i2c_read_fifo(i2c);
+		/* use atomic mode and try to force a stop bit */
+		i2c->msg_status = -EIO;
+		img_i2c_stop_start(i2c);
+		return 0;
+	}
+
+	/* Enable transaction halt on start bit */
+	if (!i2c->last_msg && i2c->line_status & LINESTAT_START_BIT_DET) {
+		img_i2c_transaction_halt(i2c, true);
+		/* we're no longer interested in the slave event */
+		i2c->int_enable &= ~INT_SLAVE_EVENT;
+	}
+
+	mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
+
+	if (i2c->msg.flags & I2C_M_RD) {
+		if (int_status & INT_FIFO_FULL_FILLING) {
+			img_i2c_read_fifo(i2c);
+			if (i2c->msg.len == 0)
+				return ISR_WAITSTOP;
+		}
+	} else {
+		if (int_status & INT_FIFO_EMPTY_EMPTYING) {
+			/*
+			 * The write fifo empty indicates that we're in the
+			 * last byte so it's safe to start a new write
+			 * transaction without losing any bytes from the
+			 * previous one.
+			 * see 2.3.7 Repeated Start Transactions.
+			 */
+			if ((int_status & INT_FIFO_EMPTY) &&
+			    i2c->msg.len == 0)
+				return ISR_WAITSTOP;
+			img_i2c_write_fifo(i2c);
+		}
+	}
+
+	return 0;
+}
+
+static irqreturn_t img_i2c_isr(int irq, void *dev_id)
+{
+	struct img_i2c *i2c = (struct img_i2c *)dev_id;
+	u32 int_status, line_status;
+	/* We handle transaction completion AFTER accessing registers */
+	unsigned int hret;
+
+	/* Read interrupt status register. */
+	int_status = img_i2c_readl(i2c, SCB_INT_STATUS_REG);
+	/* Clear detected interrupts. */
+	img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status);
+
+	/*
+	 * Read line status and clear it until it actually is clear.  We have
+	 * to be careful not to lose any line status bits that get latched.
+	 */
+	line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
+	if (line_status & LINESTAT_LATCHED) {
+		img_i2c_writel(i2c, SCB_CLEAR_REG,
+			      (line_status & LINESTAT_LATCHED)
+				>> LINESTAT_CLEAR_SHIFT);
+		img_i2c_wr_rd_fence(i2c);
+	}
+
+	spin_lock(&i2c->lock);
+
+	/* Keep track of line status bits received */
+	i2c->line_status &= ~LINESTAT_INPUT_DATA;
+	i2c->line_status |= line_status;
+
+	/*
+	 * Certain interrupts indicate that sclk low timeout is not
+	 * a problem. If any of these are set, just continue.
+	 */
+	if ((int_status & INT_SCLK_LOW_TIMEOUT) &&
+	    !(int_status & (INT_SLAVE_EVENT |
+			    INT_FIFO_EMPTY |
+			    INT_FIFO_FULL))) {
+		dev_crit(i2c->adap.dev.parent,
+			 "fatal: clock low timeout occurred %s addr 0x%02x\n",
+			 (i2c->msg.flags & I2C_M_RD) ? "reading" : "writing",
+			 i2c->msg.addr);
+		hret = ISR_FATAL(EIO);
+		goto out;
+	}
+
+	if (i2c->mode == MODE_ATOMIC)
+		hret = img_i2c_atomic(i2c, int_status, line_status);
+	else if (i2c->mode == MODE_AUTOMATIC)
+		hret = img_i2c_auto(i2c, int_status, line_status);
+	else if (i2c->mode == MODE_SEQUENCE)
+		hret = img_i2c_sequence(i2c, int_status);
+	else if (i2c->mode == MODE_WAITSTOP && (int_status & INT_SLAVE_EVENT) &&
+			 (line_status & LINESTAT_STOP_BIT_DET))
+		hret = ISR_COMPLETE(0);
+	else if (i2c->mode == MODE_RAW)
+		hret = img_i2c_raw(i2c, int_status, line_status);
+	else
+		hret = 0;
+
+	/* Clear detected level interrupts. */
+	img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status & INT_LEVEL);
+
+out:
+	if (hret & ISR_WAITSTOP) {
+		/*
+		 * Only wait for stop on last message.
+		 * Also we may already have detected the stop bit.
+		 */
+		if (!i2c->last_msg || i2c->line_status & LINESTAT_STOP_BIT_DET)
+			hret = ISR_COMPLETE(0);
+		else
+			img_i2c_switch_mode(i2c, MODE_WAITSTOP);
+	}
+
+	/* now we've finished using regs, handle transaction completion */
+	if (hret & ISR_COMPLETE_M) {
+		int status = -(hret & ISR_STATUS_M);
+
+		img_i2c_complete_transaction(i2c, status);
+		if (hret & ISR_FATAL_M)
+			img_i2c_switch_mode(i2c, MODE_FATAL);
+	}
+
+	/* Enable interrupts (int_enable may be altered by changing mode) */
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+
+	spin_unlock(&i2c->lock);
+
+	return IRQ_HANDLED;
+}
+
+/* Force a bus reset sequence and wait for it to complete */
+static int img_i2c_reset_bus(struct img_i2c *i2c)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+	reinit_completion(&i2c->msg_complete);
+	img_i2c_reset_start(i2c);
+	spin_unlock_irqrestore(&i2c->lock, flags);
+
+	ret = wait_for_completion_timeout(&i2c->msg_complete, IMG_I2C_TIMEOUT);
+	if (ret == 0)
+		return -ETIMEDOUT;
+	return 0;
+}
+
+static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			int num)
+{
+	struct img_i2c *i2c = i2c_get_adapdata(adap);
+	bool atomic = false;
+	int i, ret;
+
+	if (i2c->mode == MODE_SUSPEND) {
+		WARN(1, "refusing to service transaction in suspended state\n");
+		return -EIO;
+	}
+
+	if (i2c->mode == MODE_FATAL)
+		return -EIO;
+
+	for (i = 0; i < num; i++) {
+		if (likely(msgs[i].len))
+			continue;
+		/*
+		 * 0 byte reads are not possible because the slave could try
+		 * and pull the data line low, preventing a stop bit.
+		 */
+		if (unlikely(msgs[i].flags & I2C_M_RD))
+			return -EIO;
+		/*
+		 * 0 byte writes are possible and used for probing, but we
+		 * cannot do them in automatic mode, so use atomic mode
+		 * instead.
+		 */
+		atomic = true;
+	}
+
+	ret = clk_prepare_enable(i2c->scb_clk);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < num; i++) {
+		struct i2c_msg *msg = &msgs[i];
+		unsigned long flags;
+
+		spin_lock_irqsave(&i2c->lock, flags);
+
+		/*
+		 * Make a copy of the message struct. We mustn't modify the
+		 * original or we'll confuse drivers and i2c-dev.
+		 */
+		i2c->msg = *msg;
+		i2c->msg_status = 0;
+
+		/*
+		 * After the last message we must have waited for a stop bit.
+		 * Not waiting can cause problems when the clock is disabled
+		 * before the stop bit is sent, and the linux I2C interface
+		 * requires separate transfers not to joined with repeated
+		 * start.
+		 */
+		i2c->last_msg = (i == num - 1);
+		reinit_completion(&i2c->msg_complete);
+
+		if (atomic)
+			img_i2c_atomic_start(i2c);
+		else if (msg->flags & I2C_M_RD)
+			img_i2c_read(i2c);
+		else
+			img_i2c_write(i2c);
+		spin_unlock_irqrestore(&i2c->lock, flags);
+
+		ret = wait_for_completion_timeout(&i2c->msg_complete,
+						  IMG_I2C_TIMEOUT);
+		del_timer_sync(&i2c->check_timer);
+
+		if (ret == 0) {
+			dev_err(adap->dev.parent, "i2c transfer timed out\n");
+			i2c->msg_status = -ETIMEDOUT;
+			break;
+		}
+
+		if (i2c->msg_status)
+			break;
+	}
+
+	clk_disable_unprepare(i2c->scb_clk);
+
+	return i2c->msg_status ? i2c->msg_status : num;
+}
+
+static u32 img_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm img_i2c_algo = {
+	.master_xfer = img_i2c_xfer,
+	.functionality = img_i2c_func,
+};
+
+static int img_i2c_init(struct img_i2c *i2c)
+{
+	unsigned int clk_khz, bitrate_khz, clk_period, tckh, tckl, tsdh;
+	unsigned int i, ret, data, prescale, inc, int_bitrate, filt;
+	struct img_i2c_timings timing;
+	u32 rev;
+
+	ret = clk_prepare_enable(i2c->scb_clk);
+	if (ret)
+		return ret;
+
+	rev = img_i2c_readl(i2c, SCB_CORE_REV_REG);
+	if ((rev & 0x00ffffff) < 0x00020200) {
+		dev_info(i2c->adap.dev.parent,
+			 "Unknown hardware revision (%d.%d.%d.%d)\n",
+			 (rev >> 24) & 0xff, (rev >> 16) & 0xff,
+			 (rev >> 8) & 0xff, rev & 0xff);
+		clk_disable_unprepare(i2c->scb_clk);
+		return -EINVAL;
+	}
+
+	if (rev == REL_SOC_IP_SCB_2_2_1) {
+		i2c->need_wr_rd_fence = true;
+		dev_info(i2c->adap.dev.parent, "fence quirk enabled");
+	}
+
+	bitrate_khz = i2c->bitrate / 1000;
+	clk_khz = clk_get_rate(i2c->scb_clk) / 1000;
+
+	/* Determine what mode we're in from the bitrate */
+	timing = timings[0];
+	for (i = 0; i < ARRAY_SIZE(timings); i++) {
+		if (i2c->bitrate <= timings[i].max_bitrate) {
+			timing = timings[i];
+			break;
+		}
+	}
+
+	/* Find the prescale that would give us that inc (approx delay = 0) */
+	prescale = SCB_OPT_INC * clk_khz / (256 * 16 * bitrate_khz);
+	prescale = clamp_t(unsigned int, prescale, 1, 8);
+	clk_khz /= prescale;
+
+	/* Setup the clock increment value */
+	inc = (256 * 16 * bitrate_khz) / clk_khz;
+
+	/*
+	 * The clock generation logic allows to filter glitches on the bus.
+	 * This filter is able to remove bus glitches shorter than 50ns.
+	 * If the clock enable rate is greater than 20 MHz, no filtering
+	 * is required, so we need to disable it.
+	 * If it's between the 20-40 MHz range, there's no need to divide
+	 * the clock to get a filter.
+	 */
+	if (clk_khz < 20000) {
+		filt = SCB_FILT_DISABLE;
+	} else if (clk_khz < 40000) {
+		filt = SCB_FILT_BYPASS;
+	} else {
+		/* Calculate filter clock */
+		filt = (64000 / ((clk_khz / 1000) * SCB_FILT_GLITCH));
+
+		/* Scale up if needed */
+		if (64000 % ((clk_khz / 1000) * SCB_FILT_GLITCH))
+			inc++;
+
+		if (filt > SCB_FILT_INC_MASK)
+			filt = SCB_FILT_INC_MASK;
+
+		filt = (filt & SCB_FILT_INC_MASK) << SCB_FILT_INC_SHIFT;
+	}
+	data = filt | ((inc & SCB_INC_MASK) << SCB_INC_SHIFT) | (prescale - 1);
+	img_i2c_writel(i2c, SCB_CLK_SET_REG, data);
+
+	/* Obtain the clock period of the fx16 clock in ns */
+	clk_period = (256 * 1000000) / (clk_khz * inc);
+
+	/* Calculate the bitrate in terms of internal clock pulses */
+	int_bitrate = 1000000 / (bitrate_khz * clk_period);
+	if ((1000000 % (bitrate_khz * clk_period)) >=
+	    ((bitrate_khz * clk_period) / 2))
+		int_bitrate++;
+
+	/* Setup TCKH value */
+	tckh = timing.tckh / clk_period;
+	if (timing.tckh % clk_period)
+		tckh++;
+
+	if (tckh > 0)
+		data = tckh - 1;
+	else
+		data = 0;
+
+	img_i2c_writel(i2c, SCB_TIME_TCKH_REG, data);
+
+	/* Setup TCKL value */
+	tckl = int_bitrate - tckh;
+
+	if (tckl > 0)
+		data = tckl - 1;
+	else
+		data = 0;
+
+	img_i2c_writel(i2c, SCB_TIME_TCKL_REG, data);
+
+	/* Setup TSDH value */
+	tsdh = timing.tsdh / clk_period;
+	if (timing.tsdh % clk_period)
+		tsdh++;
+
+	if (tsdh > 1)
+		data = tsdh - 1;
+	else
+		data = 0x01;
+	img_i2c_writel(i2c, SCB_TIME_TSDH_REG, data);
+
+	/* This value is used later */
+	tsdh = data;
+
+	/* Setup TPL value */
+	data = timing.tpl / clk_period;
+	if (data > 0)
+		--data;
+	img_i2c_writel(i2c, SCB_TIME_TPL_REG, data);
+
+	/* Setup TPH value */
+	data = timing.tph / clk_period;
+	if (data > 0)
+		--data;
+	img_i2c_writel(i2c, SCB_TIME_TPH_REG, data);
+
+	/* Setup TSDL value to TPL + TSDH + 2 */
+	img_i2c_writel(i2c, SCB_TIME_TSDL_REG, data + tsdh + 2);
+
+	/* Setup TP2S value */
+	data = timing.tp2s / clk_period;
+	if (data > 0)
+		--data;
+	img_i2c_writel(i2c, SCB_TIME_TP2S_REG, data);
+
+	img_i2c_writel(i2c, SCB_TIME_TBI_REG, TIMEOUT_TBI);
+	img_i2c_writel(i2c, SCB_TIME_TSL_REG, TIMEOUT_TSL);
+	img_i2c_writel(i2c, SCB_TIME_TDL_REG, TIMEOUT_TDL);
+
+	/* Take module out of soft reset and enable clocks */
+	img_i2c_soft_reset(i2c);
+
+	/* Disable all interrupts */
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, 0);
+
+	/* Clear all interrupts */
+	img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
+
+	/* Clear the scb_line_status events */
+	img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
+
+	/* Enable interrupts */
+	img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
+
+	/* Perform a synchronous sequence to reset the bus */
+	ret = img_i2c_reset_bus(i2c);
+
+	clk_disable_unprepare(i2c->scb_clk);
+
+	return ret;
+}
+
+static int img_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct img_i2c *i2c;
+	struct resource *res;
+	int irq, ret;
+	u32 val;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct img_i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(i2c->base))
+		return PTR_ERR(i2c->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "can't get irq number\n");
+		return irq;
+	}
+
+	i2c->sys_clk = devm_clk_get(&pdev->dev, "sys");
+	if (IS_ERR(i2c->sys_clk)) {
+		dev_err(&pdev->dev, "can't get system clock\n");
+		return PTR_ERR(i2c->sys_clk);
+	}
+
+	i2c->scb_clk = devm_clk_get(&pdev->dev, "scb");
+	if (IS_ERR(i2c->scb_clk)) {
+		dev_err(&pdev->dev, "can't get core clock\n");
+		return PTR_ERR(i2c->scb_clk);
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, img_i2c_isr, 0,
+			       pdev->name, i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "can't request irq %d\n", irq);
+		return ret;
+	}
+
+	/* Set up the exception check timer */
+	init_timer(&i2c->check_timer);
+	i2c->check_timer.function = img_i2c_check_timer;
+	i2c->check_timer.data = (unsigned long)i2c;
+
+	i2c->bitrate = timings[0].max_bitrate;
+	if (!of_property_read_u32(node, "clock-frequency", &val))
+		i2c->bitrate = val;
+
+	i2c_set_adapdata(&i2c->adap, i2c);
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.dev.of_node = node;
+	i2c->adap.owner = THIS_MODULE;
+	i2c->adap.algo = &img_i2c_algo;
+	i2c->adap.retries = 5;
+	i2c->adap.nr = pdev->id;
+	snprintf(i2c->adap.name, sizeof(i2c->adap.name), "IMG SCB I2C");
+
+	img_i2c_switch_mode(i2c, MODE_INACTIVE);
+	spin_lock_init(&i2c->lock);
+	init_completion(&i2c->msg_complete);
+
+	platform_set_drvdata(pdev, i2c);
+
+	ret = clk_prepare_enable(i2c->sys_clk);
+	if (ret)
+		return ret;
+
+	ret = img_i2c_init(i2c);
+	if (ret)
+		goto disable_clk;
+
+	ret = i2c_add_numbered_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add adapter\n");
+		goto disable_clk;
+	}
+
+	return 0;
+
+disable_clk:
+	clk_disable_unprepare(i2c->sys_clk);
+	return ret;
+}
+
+static int img_i2c_remove(struct platform_device *dev)
+{
+	struct img_i2c *i2c = platform_get_drvdata(dev);
+
+	i2c_del_adapter(&i2c->adap);
+	clk_disable_unprepare(i2c->sys_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int img_i2c_suspend(struct device *dev)
+{
+	struct img_i2c *i2c = dev_get_drvdata(dev);
+
+	img_i2c_switch_mode(i2c, MODE_SUSPEND);
+
+	clk_disable_unprepare(i2c->sys_clk);
+
+	return 0;
+}
+
+static int img_i2c_resume(struct device *dev)
+{
+	struct img_i2c *i2c = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(i2c->sys_clk);
+	if (ret)
+		return ret;
+
+	img_i2c_init(i2c);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(img_i2c_pm, img_i2c_suspend, img_i2c_resume);
+
+static const struct of_device_id img_scb_i2c_match[] = {
+	{ .compatible = "img,scb-i2c" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, img_scb_i2c_match);
+
+static struct platform_driver img_scb_i2c_driver = {
+	.driver = {
+		.name		= "img-i2c-scb",
+		.of_match_table	= img_scb_i2c_match,
+		.pm		= &img_i2c_pm,
+	},
+	.probe = img_i2c_probe,
+	.remove = img_i2c_remove,
+};
+module_platform_driver(img_scb_i2c_driver);
+
+MODULE_AUTHOR("James Hogan <james.hogan@imgtec.com>");
+MODULE_DESCRIPTION("IMG host I2C driver");
+MODULE_LICENSE("GPL v2");