Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 1135 insertions, 0 deletions

diff --git a/kernel/drivers/i2c/busses/i2c-nomadik.c b/kernel/drivers/i2c/busses/i2c-nomadik.c
new file mode 100644
index 000000000..bcd17e8cb
--- /dev/null
+++ b/kernel/drivers/i2c/busses/i2c-nomadik.c
@@ -0,0 +1,1135 @@
+/*
+ * Copyright (C) 2009 ST-Ericsson SA
+ * Copyright (C) 2009 STMicroelectronics
+ *
+ * I2C master mode controller driver, used in Nomadik 8815
+ * and Ux500 platforms.
+ *
+ * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
+ * Author: Sachin Verma <sachin.verma@st.com>
+ *
+ * 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.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/amba/bus.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
+
+#define DRIVER_NAME "nmk-i2c"
+
+/* I2C Controller register offsets */
+#define I2C_CR		(0x000)
+#define I2C_SCR		(0x004)
+#define I2C_HSMCR	(0x008)
+#define I2C_MCR		(0x00C)
+#define I2C_TFR		(0x010)
+#define I2C_SR		(0x014)
+#define I2C_RFR		(0x018)
+#define I2C_TFTR	(0x01C)
+#define I2C_RFTR	(0x020)
+#define I2C_DMAR	(0x024)
+#define I2C_BRCR	(0x028)
+#define I2C_IMSCR	(0x02C)
+#define I2C_RISR	(0x030)
+#define I2C_MISR	(0x034)
+#define I2C_ICR		(0x038)
+
+/* Control registers */
+#define I2C_CR_PE		(0x1 << 0)	/* Peripheral Enable */
+#define I2C_CR_OM		(0x3 << 1)	/* Operating mode */
+#define I2C_CR_SAM		(0x1 << 3)	/* Slave addressing mode */
+#define I2C_CR_SM		(0x3 << 4)	/* Speed mode */
+#define I2C_CR_SGCM		(0x1 << 6)	/* Slave general call mode */
+#define I2C_CR_FTX		(0x1 << 7)	/* Flush Transmit */
+#define I2C_CR_FRX		(0x1 << 8)	/* Flush Receive */
+#define I2C_CR_DMA_TX_EN	(0x1 << 9)	/* DMA Tx enable */
+#define I2C_CR_DMA_RX_EN	(0x1 << 10)	/* DMA Rx Enable */
+#define I2C_CR_DMA_SLE		(0x1 << 11)	/* DMA sync. logic enable */
+#define I2C_CR_LM		(0x1 << 12)	/* Loopback mode */
+#define I2C_CR_FON		(0x3 << 13)	/* Filtering on */
+#define I2C_CR_FS		(0x3 << 15)	/* Force stop enable */
+
+/* Master controller (MCR) register */
+#define I2C_MCR_OP		(0x1 << 0)	/* Operation */
+#define I2C_MCR_A7		(0x7f << 1)	/* 7-bit address */
+#define I2C_MCR_EA10		(0x7 << 8)	/* 10-bit Extended address */
+#define I2C_MCR_SB		(0x1 << 11)	/* Extended address */
+#define I2C_MCR_AM		(0x3 << 12)	/* Address type */
+#define I2C_MCR_STOP		(0x1 << 14)	/* Stop condition */
+#define I2C_MCR_LENGTH		(0x7ff << 15)	/* Transaction length */
+
+/* Status register (SR) */
+#define I2C_SR_OP		(0x3 << 0)	/* Operation */
+#define I2C_SR_STATUS		(0x3 << 2)	/* controller status */
+#define I2C_SR_CAUSE		(0x7 << 4)	/* Abort cause */
+#define I2C_SR_TYPE		(0x3 << 7)	/* Receive type */
+#define I2C_SR_LENGTH		(0x7ff << 9)	/* Transfer length */
+
+/* Interrupt mask set/clear (IMSCR) bits */
+#define I2C_IT_TXFE		(0x1 << 0)
+#define I2C_IT_TXFNE		(0x1 << 1)
+#define I2C_IT_TXFF		(0x1 << 2)
+#define I2C_IT_TXFOVR		(0x1 << 3)
+#define I2C_IT_RXFE		(0x1 << 4)
+#define I2C_IT_RXFNF		(0x1 << 5)
+#define I2C_IT_RXFF		(0x1 << 6)
+#define I2C_IT_RFSR		(0x1 << 16)
+#define I2C_IT_RFSE		(0x1 << 17)
+#define I2C_IT_WTSR		(0x1 << 18)
+#define I2C_IT_MTD		(0x1 << 19)
+#define I2C_IT_STD		(0x1 << 20)
+#define I2C_IT_MAL		(0x1 << 24)
+#define I2C_IT_BERR		(0x1 << 25)
+#define I2C_IT_MTDWS		(0x1 << 28)
+
+#define GEN_MASK(val, mask, sb)  (((val) << (sb)) & (mask))
+
+/* some bits in ICR are reserved */
+#define I2C_CLEAR_ALL_INTS	0x131f007f
+
+/* first three msb bits are reserved */
+#define IRQ_MASK(mask)		(mask & 0x1fffffff)
+
+/* maximum threshold value */
+#define MAX_I2C_FIFO_THRESHOLD	15
+
+enum i2c_freq_mode {
+	I2C_FREQ_MODE_STANDARD,		/* up to 100 Kb/s */
+	I2C_FREQ_MODE_FAST,		/* up to 400 Kb/s */
+	I2C_FREQ_MODE_HIGH_SPEED,	/* up to 3.4 Mb/s */
+	I2C_FREQ_MODE_FAST_PLUS,	/* up to 1 Mb/s */
+};
+
+/**
+ * struct i2c_vendor_data - per-vendor variations
+ * @has_mtdws: variant has the MTDWS bit
+ * @fifodepth: variant FIFO depth
+ */
+struct i2c_vendor_data {
+	bool has_mtdws;
+	u32 fifodepth;
+};
+
+enum i2c_status {
+	I2C_NOP,
+	I2C_ON_GOING,
+	I2C_OK,
+	I2C_ABORT
+};
+
+/* operation */
+enum i2c_operation {
+	I2C_NO_OPERATION = 0xff,
+	I2C_WRITE = 0x00,
+	I2C_READ = 0x01
+};
+
+/**
+ * struct i2c_nmk_client - client specific data
+ * @slave_adr: 7-bit slave address
+ * @count: no. bytes to be transferred
+ * @buffer: client data buffer
+ * @xfer_bytes: bytes transferred till now
+ * @operation: current I2C operation
+ */
+struct i2c_nmk_client {
+	unsigned short		slave_adr;
+	unsigned long		count;
+	unsigned char		*buffer;
+	unsigned long		xfer_bytes;
+	enum i2c_operation	operation;
+};
+
+/**
+ * struct nmk_i2c_dev - private data structure of the controller.
+ * @vendor: vendor data for this variant.
+ * @adev: parent amba device.
+ * @adap: corresponding I2C adapter.
+ * @irq: interrupt line for the controller.
+ * @virtbase: virtual io memory area.
+ * @clk: hardware i2c block clock.
+ * @cli: holder of client specific data.
+ * @clk_freq: clock frequency for the operation mode
+ * @tft: Tx FIFO Threshold in bytes
+ * @rft: Rx FIFO Threshold in bytes
+ * @timeout Slave response timeout (ms)
+ * @sm: speed mode
+ * @stop: stop condition.
+ * @xfer_complete: acknowledge completion for a I2C message.
+ * @result: controller propogated result.
+ */
+struct nmk_i2c_dev {
+	struct i2c_vendor_data		*vendor;
+	struct amba_device		*adev;
+	struct i2c_adapter		adap;
+	int				irq;
+	void __iomem			*virtbase;
+	struct clk			*clk;
+	struct i2c_nmk_client		cli;
+	u32				clk_freq;
+	unsigned char			tft;
+	unsigned char			rft;
+	int				timeout;
+	enum i2c_freq_mode		sm;
+	int				stop;
+	struct completion		xfer_complete;
+	int				result;
+};
+
+/* controller's abort causes */
+static const char *abort_causes[] = {
+	"no ack received after address transmission",
+	"no ack received during data phase",
+	"ack received after xmission of master code",
+	"master lost arbitration",
+	"slave restarts",
+	"slave reset",
+	"overflow, maxsize is 2047 bytes",
+};
+
+static inline void i2c_set_bit(void __iomem *reg, u32 mask)
+{
+	writel(readl(reg) | mask, reg);
+}
+
+static inline void i2c_clr_bit(void __iomem *reg, u32 mask)
+{
+	writel(readl(reg) & ~mask, reg);
+}
+
+/**
+ * flush_i2c_fifo() - This function flushes the I2C FIFO
+ * @dev: private data of I2C Driver
+ *
+ * This function flushes the I2C Tx and Rx FIFOs. It returns
+ * 0 on successful flushing of FIFO
+ */
+static int flush_i2c_fifo(struct nmk_i2c_dev *dev)
+{
+#define LOOP_ATTEMPTS 10
+	int i;
+	unsigned long timeout;
+
+	/*
+	 * flush the transmit and receive FIFO. The flushing
+	 * operation takes several cycles before to be completed.
+	 * On the completion, the I2C internal logic clears these
+	 * bits, until then no one must access Tx, Rx FIFO and
+	 * should poll on these bits waiting for the completion.
+	 */
+	writel((I2C_CR_FTX | I2C_CR_FRX), dev->virtbase + I2C_CR);
+
+	for (i = 0; i < LOOP_ATTEMPTS; i++) {
+		timeout = jiffies + dev->adap.timeout;
+
+		while (!time_after(jiffies, timeout)) {
+			if ((readl(dev->virtbase + I2C_CR) &
+				(I2C_CR_FTX | I2C_CR_FRX)) == 0)
+					return 0;
+		}
+	}
+
+	dev_err(&dev->adev->dev,
+		"flushing operation timed out giving up after %d attempts",
+		LOOP_ATTEMPTS);
+
+	return -ETIMEDOUT;
+}
+
+/**
+ * disable_all_interrupts() - Disable all interrupts of this I2c Bus
+ * @dev: private data of I2C Driver
+ */
+static void disable_all_interrupts(struct nmk_i2c_dev *dev)
+{
+	u32 mask = IRQ_MASK(0);
+	writel(mask, dev->virtbase + I2C_IMSCR);
+}
+
+/**
+ * clear_all_interrupts() - Clear all interrupts of I2C Controller
+ * @dev: private data of I2C Driver
+ */
+static void clear_all_interrupts(struct nmk_i2c_dev *dev)
+{
+	u32 mask;
+	mask = IRQ_MASK(I2C_CLEAR_ALL_INTS);
+	writel(mask, dev->virtbase + I2C_ICR);
+}
+
+/**
+ * init_hw() - initialize the I2C hardware
+ * @dev: private data of I2C Driver
+ */
+static int init_hw(struct nmk_i2c_dev *dev)
+{
+	int stat;
+
+	stat = flush_i2c_fifo(dev);
+	if (stat)
+		goto exit;
+
+	/* disable the controller */
+	i2c_clr_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
+
+	disable_all_interrupts(dev);
+
+	clear_all_interrupts(dev);
+
+	dev->cli.operation = I2C_NO_OPERATION;
+
+exit:
+	return stat;
+}
+
+/* enable peripheral, master mode operation */
+#define DEFAULT_I2C_REG_CR	((1 << 1) | I2C_CR_PE)
+
+/**
+ * load_i2c_mcr_reg() - load the MCR register
+ * @dev: private data of controller
+ * @flags: message flags
+ */
+static u32 load_i2c_mcr_reg(struct nmk_i2c_dev *dev, u16 flags)
+{
+	u32 mcr = 0;
+	unsigned short slave_adr_3msb_bits;
+
+	mcr |= GEN_MASK(dev->cli.slave_adr, I2C_MCR_A7, 1);
+
+	if (unlikely(flags & I2C_M_TEN)) {
+		/* 10-bit address transaction */
+		mcr |= GEN_MASK(2, I2C_MCR_AM, 12);
+		/*
+		 * Get the top 3 bits.
+		 * EA10 represents extended address in MCR. This includes
+		 * the extension (MSB bits) of the 7 bit address loaded
+		 * in A7
+		 */
+		slave_adr_3msb_bits = (dev->cli.slave_adr >> 7) & 0x7;
+
+		mcr |= GEN_MASK(slave_adr_3msb_bits, I2C_MCR_EA10, 8);
+	} else {
+		/* 7-bit address transaction */
+		mcr |= GEN_MASK(1, I2C_MCR_AM, 12);
+	}
+
+	/* start byte procedure not applied */
+	mcr |= GEN_MASK(0, I2C_MCR_SB, 11);
+
+	/* check the operation, master read/write? */
+	if (dev->cli.operation == I2C_WRITE)
+		mcr |= GEN_MASK(I2C_WRITE, I2C_MCR_OP, 0);
+	else
+		mcr |= GEN_MASK(I2C_READ, I2C_MCR_OP, 0);
+
+	/* stop or repeated start? */
+	if (dev->stop)
+		mcr |= GEN_MASK(1, I2C_MCR_STOP, 14);
+	else
+		mcr &= ~(GEN_MASK(1, I2C_MCR_STOP, 14));
+
+	mcr |= GEN_MASK(dev->cli.count, I2C_MCR_LENGTH, 15);
+
+	return mcr;
+}
+
+/**
+ * setup_i2c_controller() - setup the controller
+ * @dev: private data of controller
+ */
+static void setup_i2c_controller(struct nmk_i2c_dev *dev)
+{
+	u32 brcr1, brcr2;
+	u32 i2c_clk, div;
+	u32 ns;
+	u16 slsu;
+
+	writel(0x0, dev->virtbase + I2C_CR);
+	writel(0x0, dev->virtbase + I2C_HSMCR);
+	writel(0x0, dev->virtbase + I2C_TFTR);
+	writel(0x0, dev->virtbase + I2C_RFTR);
+	writel(0x0, dev->virtbase + I2C_DMAR);
+
+	i2c_clk = clk_get_rate(dev->clk);
+
+	/*
+	 * set the slsu:
+	 *
+	 * slsu defines the data setup time after SCL clock
+	 * stretching in terms of i2c clk cycles + 1 (zero means
+	 * "wait one cycle"), the needed setup time for the three
+	 * modes are 250ns, 100ns, 10ns respectively.
+	 *
+	 * As the time for one cycle T in nanoseconds is
+	 * T = (1/f) * 1000000000 =>
+	 * slsu = cycles / (1000000000 / f) + 1
+	 */
+	ns = DIV_ROUND_UP_ULL(1000000000ULL, i2c_clk);
+	switch (dev->sm) {
+	case I2C_FREQ_MODE_FAST:
+	case I2C_FREQ_MODE_FAST_PLUS:
+		slsu = DIV_ROUND_UP(100, ns); /* Fast */
+		break;
+	case I2C_FREQ_MODE_HIGH_SPEED:
+		slsu = DIV_ROUND_UP(10, ns); /* High */
+		break;
+	case I2C_FREQ_MODE_STANDARD:
+	default:
+		slsu = DIV_ROUND_UP(250, ns); /* Standard */
+		break;
+	}
+	slsu += 1;
+
+	dev_dbg(&dev->adev->dev, "calculated SLSU = %04x\n", slsu);
+	writel(slsu << 16, dev->virtbase + I2C_SCR);
+
+	/*
+	 * The spec says, in case of std. mode the divider is
+	 * 2 whereas it is 3 for fast and fastplus mode of
+	 * operation. TODO - high speed support.
+	 */
+	div = (dev->clk_freq > 100000) ? 3 : 2;
+
+	/*
+	 * generate the mask for baud rate counters. The controller
+	 * has two baud rate counters. One is used for High speed
+	 * operation, and the other is for std, fast mode, fast mode
+	 * plus operation. Currently we do not supprt high speed mode
+	 * so set brcr1 to 0.
+	 */
+	brcr1 = 0 << 16;
+	brcr2 = (i2c_clk/(dev->clk_freq * div)) & 0xffff;
+
+	/* set the baud rate counter register */
+	writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
+
+	/*
+	 * set the speed mode. Currently we support
+	 * only standard and fast mode of operation
+	 * TODO - support for fast mode plus (up to 1Mb/s)
+	 * and high speed (up to 3.4 Mb/s)
+	 */
+	if (dev->sm > I2C_FREQ_MODE_FAST) {
+		dev_err(&dev->adev->dev,
+			"do not support this mode defaulting to std. mode\n");
+		brcr2 = i2c_clk/(100000 * 2) & 0xffff;
+		writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
+		writel(I2C_FREQ_MODE_STANDARD << 4,
+				dev->virtbase + I2C_CR);
+	}
+	writel(dev->sm << 4, dev->virtbase + I2C_CR);
+
+	/* set the Tx and Rx FIFO threshold */
+	writel(dev->tft, dev->virtbase + I2C_TFTR);
+	writel(dev->rft, dev->virtbase + I2C_RFTR);
+}
+
+/**
+ * read_i2c() - Read from I2C client device
+ * @dev: private data of I2C Driver
+ * @flags: message flags
+ *
+ * This function reads from i2c client device when controller is in
+ * master mode. There is a completion timeout. If there is no transfer
+ * before timeout error is returned.
+ */
+static int read_i2c(struct nmk_i2c_dev *dev, u16 flags)
+{
+	int status = 0;
+	u32 mcr, irq_mask;
+	unsigned long timeout;
+
+	mcr = load_i2c_mcr_reg(dev, flags);
+	writel(mcr, dev->virtbase + I2C_MCR);
+
+	/* load the current CR value */
+	writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
+			dev->virtbase + I2C_CR);
+
+	/* enable the controller */
+	i2c_set_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
+
+	init_completion(&dev->xfer_complete);
+
+	/* enable interrupts by setting the mask */
+	irq_mask = (I2C_IT_RXFNF | I2C_IT_RXFF |
+			I2C_IT_MAL | I2C_IT_BERR);
+
+	if (dev->stop || !dev->vendor->has_mtdws)
+		irq_mask |= I2C_IT_MTD;
+	else
+		irq_mask |= I2C_IT_MTDWS;
+
+	irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
+
+	writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
+			dev->virtbase + I2C_IMSCR);
+
+	timeout = wait_for_completion_timeout(
+		&dev->xfer_complete, dev->adap.timeout);
+
+	if (timeout == 0) {
+		/* Controller timed out */
+		dev_err(&dev->adev->dev, "read from slave 0x%x timed out\n",
+				dev->cli.slave_adr);
+		status = -ETIMEDOUT;
+	}
+	return status;
+}
+
+static void fill_tx_fifo(struct nmk_i2c_dev *dev, int no_bytes)
+{
+	int count;
+
+	for (count = (no_bytes - 2);
+			(count > 0) &&
+			(dev->cli.count != 0);
+			count--) {
+		/* write to the Tx FIFO */
+		writeb(*dev->cli.buffer,
+			dev->virtbase + I2C_TFR);
+		dev->cli.buffer++;
+		dev->cli.count--;
+		dev->cli.xfer_bytes++;
+	}
+
+}
+
+/**
+ * write_i2c() - Write data to I2C client.
+ * @dev: private data of I2C Driver
+ * @flags: message flags
+ *
+ * This function writes data to I2C client
+ */
+static int write_i2c(struct nmk_i2c_dev *dev, u16 flags)
+{
+	u32 status = 0;
+	u32 mcr, irq_mask;
+	unsigned long timeout;
+
+	mcr = load_i2c_mcr_reg(dev, flags);
+
+	writel(mcr, dev->virtbase + I2C_MCR);
+
+	/* load the current CR value */
+	writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
+			dev->virtbase + I2C_CR);
+
+	/* enable the controller */
+	i2c_set_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
+
+	init_completion(&dev->xfer_complete);
+
+	/* enable interrupts by settings the masks */
+	irq_mask = (I2C_IT_TXFOVR | I2C_IT_MAL | I2C_IT_BERR);
+
+	/* Fill the TX FIFO with transmit data */
+	fill_tx_fifo(dev, MAX_I2C_FIFO_THRESHOLD);
+
+	if (dev->cli.count != 0)
+		irq_mask |= I2C_IT_TXFNE;
+
+	/*
+	 * check if we want to transfer a single or multiple bytes, if so
+	 * set the MTDWS bit (Master Transaction Done Without Stop)
+	 * to start repeated start operation
+	 */
+	if (dev->stop || !dev->vendor->has_mtdws)
+		irq_mask |= I2C_IT_MTD;
+	else
+		irq_mask |= I2C_IT_MTDWS;
+
+	irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
+
+	writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
+			dev->virtbase + I2C_IMSCR);
+
+	timeout = wait_for_completion_timeout(
+		&dev->xfer_complete, dev->adap.timeout);
+
+	if (timeout == 0) {
+		/* Controller timed out */
+		dev_err(&dev->adev->dev, "write to slave 0x%x timed out\n",
+				dev->cli.slave_adr);
+		status = -ETIMEDOUT;
+	}
+
+	return status;
+}
+
+/**
+ * nmk_i2c_xfer_one() - transmit a single I2C message
+ * @dev: device with a message encoded into it
+ * @flags: message flags
+ */
+static int nmk_i2c_xfer_one(struct nmk_i2c_dev *dev, u16 flags)
+{
+	int status;
+
+	if (flags & I2C_M_RD) {
+		/* read operation */
+		dev->cli.operation = I2C_READ;
+		status = read_i2c(dev, flags);
+	} else {
+		/* write operation */
+		dev->cli.operation = I2C_WRITE;
+		status = write_i2c(dev, flags);
+	}
+
+	if (status || (dev->result)) {
+		u32 i2c_sr;
+		u32 cause;
+
+		i2c_sr = readl(dev->virtbase + I2C_SR);
+		/*
+		 * Check if the controller I2C operation status
+		 * is set to ABORT(11b).
+		 */
+		if (((i2c_sr >> 2) & 0x3) == 0x3) {
+			/* get the abort cause */
+			cause =	(i2c_sr >> 4) & 0x7;
+			dev_err(&dev->adev->dev, "%s\n",
+				cause >= ARRAY_SIZE(abort_causes) ?
+				"unknown reason" :
+				abort_causes[cause]);
+		}
+
+		(void) init_hw(dev);
+
+		status = status ? status : dev->result;
+	}
+
+	return status;
+}
+
+/**
+ * nmk_i2c_xfer() - I2C transfer function used by kernel framework
+ * @i2c_adap: Adapter pointer to the controller
+ * @msgs: Pointer to data to be written.
+ * @num_msgs: Number of messages to be executed
+ *
+ * This is the function called by the generic kernel i2c_transfer()
+ * or i2c_smbus...() API calls. Note that this code is protected by the
+ * semaphore set in the kernel i2c_transfer() function.
+ *
+ * NOTE:
+ * READ TRANSFER : We impose a restriction of the first message to be the
+ *		index message for any read transaction.
+ *		- a no index is coded as '0',
+ *		- 2byte big endian index is coded as '3'
+ *		!!! msg[0].buf holds the actual index.
+ *		This is compatible with generic messages of smbus emulator
+ *		that send a one byte index.
+ *		eg. a I2C transation to read 2 bytes from index 0
+ *			idx = 0;
+ *			msg[0].addr = client->addr;
+ *			msg[0].flags = 0x0;
+ *			msg[0].len = 1;
+ *			msg[0].buf = &idx;
+ *
+ *			msg[1].addr = client->addr;
+ *			msg[1].flags = I2C_M_RD;
+ *			msg[1].len = 2;
+ *			msg[1].buf = rd_buff
+ *			i2c_transfer(adap, msg, 2);
+ *
+ * WRITE TRANSFER : The I2C standard interface interprets all data as payload.
+ *		If you want to emulate an SMBUS write transaction put the
+ *		index as first byte(or first and second) in the payload.
+ *		eg. a I2C transation to write 2 bytes from index 1
+ *			wr_buff[0] = 0x1;
+ *			wr_buff[1] = 0x23;
+ *			wr_buff[2] = 0x46;
+ *			msg[0].flags = 0x0;
+ *			msg[0].len = 3;
+ *			msg[0].buf = wr_buff;
+ *			i2c_transfer(adap, msg, 1);
+ *
+ * To read or write a block of data (multiple bytes) using SMBUS emulation
+ * please use the i2c_smbus_read_i2c_block_data()
+ * or i2c_smbus_write_i2c_block_data() API
+ */
+static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
+		struct i2c_msg msgs[], int num_msgs)
+{
+	int status = 0;
+	int i;
+	struct nmk_i2c_dev *dev = i2c_get_adapdata(i2c_adap);
+	int j;
+
+	pm_runtime_get_sync(&dev->adev->dev);
+
+	/* Attempt three times to send the message queue */
+	for (j = 0; j < 3; j++) {
+		/* setup the i2c controller */
+		setup_i2c_controller(dev);
+
+		for (i = 0; i < num_msgs; i++) {
+			dev->cli.slave_adr	= msgs[i].addr;
+			dev->cli.buffer		= msgs[i].buf;
+			dev->cli.count		= msgs[i].len;
+			dev->stop = (i < (num_msgs - 1)) ? 0 : 1;
+			dev->result = 0;
+
+			status = nmk_i2c_xfer_one(dev, msgs[i].flags);
+			if (status != 0)
+				break;
+		}
+		if (status == 0)
+			break;
+	}
+
+	pm_runtime_put_sync(&dev->adev->dev);
+
+	/* return the no. messages processed */
+	if (status)
+		return status;
+	else
+		return num_msgs;
+}
+
+/**
+ * disable_interrupts() - disable the interrupts
+ * @dev: private data of controller
+ * @irq: interrupt number
+ */
+static int disable_interrupts(struct nmk_i2c_dev *dev, u32 irq)
+{
+	irq = IRQ_MASK(irq);
+	writel(readl(dev->virtbase + I2C_IMSCR) & ~(I2C_CLEAR_ALL_INTS & irq),
+			dev->virtbase + I2C_IMSCR);
+	return 0;
+}
+
+/**
+ * i2c_irq_handler() - interrupt routine
+ * @irq: interrupt number
+ * @arg: data passed to the handler
+ *
+ * This is the interrupt handler for the i2c driver. Currently
+ * it handles the major interrupts like Rx & Tx FIFO management
+ * interrupts, master transaction interrupts, arbitration and
+ * bus error interrupts. The rest of the interrupts are treated as
+ * unhandled.
+ */
+static irqreturn_t i2c_irq_handler(int irq, void *arg)
+{
+	struct nmk_i2c_dev *dev = arg;
+	u32 tft, rft;
+	u32 count;
+	u32 misr, src;
+
+	/* load Tx FIFO and Rx FIFO threshold values */
+	tft = readl(dev->virtbase + I2C_TFTR);
+	rft = readl(dev->virtbase + I2C_RFTR);
+
+	/* read interrupt status register */
+	misr = readl(dev->virtbase + I2C_MISR);
+
+	src = __ffs(misr);
+	switch ((1 << src)) {
+
+	/* Transmit FIFO nearly empty interrupt */
+	case I2C_IT_TXFNE:
+	{
+		if (dev->cli.operation == I2C_READ) {
+			/*
+			 * in read operation why do we care for writing?
+			 * so disable the Transmit FIFO interrupt
+			 */
+			disable_interrupts(dev, I2C_IT_TXFNE);
+		} else {
+			fill_tx_fifo(dev, (MAX_I2C_FIFO_THRESHOLD - tft));
+			/*
+			 * if done, close the transfer by disabling the
+			 * corresponding TXFNE interrupt
+			 */
+			if (dev->cli.count == 0)
+				disable_interrupts(dev,	I2C_IT_TXFNE);
+		}
+	}
+	break;
+
+	/*
+	 * Rx FIFO nearly full interrupt.
+	 * This is set when the numer of entries in Rx FIFO is
+	 * greater or equal than the threshold value programmed
+	 * in RFT
+	 */
+	case I2C_IT_RXFNF:
+		for (count = rft; count > 0; count--) {
+			/* Read the Rx FIFO */
+			*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
+			dev->cli.buffer++;
+		}
+		dev->cli.count -= rft;
+		dev->cli.xfer_bytes += rft;
+		break;
+
+	/* Rx FIFO full */
+	case I2C_IT_RXFF:
+		for (count = MAX_I2C_FIFO_THRESHOLD; count > 0; count--) {
+			*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
+			dev->cli.buffer++;
+		}
+		dev->cli.count -= MAX_I2C_FIFO_THRESHOLD;
+		dev->cli.xfer_bytes += MAX_I2C_FIFO_THRESHOLD;
+		break;
+
+	/* Master Transaction Done with/without stop */
+	case I2C_IT_MTD:
+	case I2C_IT_MTDWS:
+		if (dev->cli.operation == I2C_READ) {
+			while (!(readl(dev->virtbase + I2C_RISR)
+				 & I2C_IT_RXFE)) {
+				if (dev->cli.count == 0)
+					break;
+				*dev->cli.buffer =
+					readb(dev->virtbase + I2C_RFR);
+				dev->cli.buffer++;
+				dev->cli.count--;
+				dev->cli.xfer_bytes++;
+			}
+		}
+
+		disable_all_interrupts(dev);
+		clear_all_interrupts(dev);
+
+		if (dev->cli.count) {
+			dev->result = -EIO;
+			dev_err(&dev->adev->dev,
+				"%lu bytes still remain to be xfered\n",
+				dev->cli.count);
+			(void) init_hw(dev);
+		}
+		complete(&dev->xfer_complete);
+
+		break;
+
+	/* Master Arbitration lost interrupt */
+	case I2C_IT_MAL:
+		dev->result = -EIO;
+		(void) init_hw(dev);
+
+		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MAL);
+		complete(&dev->xfer_complete);
+
+		break;
+
+	/*
+	 * Bus Error interrupt.
+	 * This happens when an unexpected start/stop condition occurs
+	 * during the transaction.
+	 */
+	case I2C_IT_BERR:
+		dev->result = -EIO;
+		/* get the status */
+		if (((readl(dev->virtbase + I2C_SR) >> 2) & 0x3) == I2C_ABORT)
+			(void) init_hw(dev);
+
+		i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_BERR);
+		complete(&dev->xfer_complete);
+
+		break;
+
+	/*
+	 * Tx FIFO overrun interrupt.
+	 * This is set when a write operation in Tx FIFO is performed and
+	 * the Tx FIFO is full.
+	 */
+	case I2C_IT_TXFOVR:
+		dev->result = -EIO;
+		(void) init_hw(dev);
+
+		dev_err(&dev->adev->dev, "Tx Fifo Over run\n");
+		complete(&dev->xfer_complete);
+
+		break;
+
+	/* unhandled interrupts by this driver - TODO*/
+	case I2C_IT_TXFE:
+	case I2C_IT_TXFF:
+	case I2C_IT_RXFE:
+	case I2C_IT_RFSR:
+	case I2C_IT_RFSE:
+	case I2C_IT_WTSR:
+	case I2C_IT_STD:
+		dev_err(&dev->adev->dev, "unhandled Interrupt\n");
+		break;
+	default:
+		dev_err(&dev->adev->dev, "spurious Interrupt..\n");
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int nmk_i2c_suspend_late(struct device *dev)
+{
+	int ret;
+
+	ret = pm_runtime_force_suspend(dev);
+	if (ret)
+		return ret;
+
+	pinctrl_pm_select_sleep_state(dev);
+	return 0;
+}
+
+static int nmk_i2c_resume_early(struct device *dev)
+{
+	return pm_runtime_force_resume(dev);
+}
+#endif
+
+#ifdef CONFIG_PM
+static int nmk_i2c_runtime_suspend(struct device *dev)
+{
+	struct amba_device *adev = to_amba_device(dev);
+	struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
+
+	clk_disable_unprepare(nmk_i2c->clk);
+	pinctrl_pm_select_idle_state(dev);
+	return 0;
+}
+
+static int nmk_i2c_runtime_resume(struct device *dev)
+{
+	struct amba_device *adev = to_amba_device(dev);
+	struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
+	int ret;
+
+	ret = clk_prepare_enable(nmk_i2c->clk);
+	if (ret) {
+		dev_err(dev, "can't prepare_enable clock\n");
+		return ret;
+	}
+
+	pinctrl_pm_select_default_state(dev);
+
+	ret = init_hw(nmk_i2c);
+	if (ret) {
+		clk_disable_unprepare(nmk_i2c->clk);
+		pinctrl_pm_select_idle_state(dev);
+	}
+
+	return ret;
+}
+#endif
+
+static const struct dev_pm_ops nmk_i2c_pm = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(nmk_i2c_suspend_late, nmk_i2c_resume_early)
+	SET_RUNTIME_PM_OPS(nmk_i2c_runtime_suspend,
+			nmk_i2c_runtime_resume,
+			NULL)
+};
+
+static unsigned int nmk_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
+}
+
+static const struct i2c_algorithm nmk_i2c_algo = {
+	.master_xfer	= nmk_i2c_xfer,
+	.functionality	= nmk_i2c_functionality
+};
+
+static void nmk_i2c_of_probe(struct device_node *np,
+			     struct nmk_i2c_dev *nmk)
+{
+	/* Default to 100 kHz if no frequency is given in the node */
+	if (of_property_read_u32(np, "clock-frequency", &nmk->clk_freq))
+		nmk->clk_freq = 100000;
+
+	/* This driver only supports 'standard' and 'fast' modes of operation. */
+	if (nmk->clk_freq <= 100000)
+		nmk->sm = I2C_FREQ_MODE_STANDARD;
+	else
+		nmk->sm = I2C_FREQ_MODE_FAST;
+	nmk->tft = 1; /* Tx FIFO threshold */
+	nmk->rft = 8; /* Rx FIFO threshold */
+	nmk->timeout = 200; /* Slave response timeout(ms) */
+}
+
+static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
+{
+	int ret = 0;
+	struct device_node *np = adev->dev.of_node;
+	struct nmk_i2c_dev	*dev;
+	struct i2c_adapter *adap;
+	struct i2c_vendor_data *vendor = id->data;
+	u32 max_fifo_threshold = (vendor->fifodepth / 2) - 1;
+
+	dev = devm_kzalloc(&adev->dev, sizeof(struct nmk_i2c_dev), GFP_KERNEL);
+	if (!dev) {
+		dev_err(&adev->dev, "cannot allocate memory\n");
+		ret = -ENOMEM;
+		goto err_no_mem;
+	}
+	dev->vendor = vendor;
+	dev->adev = adev;
+	nmk_i2c_of_probe(np, dev);
+
+	if (dev->tft > max_fifo_threshold) {
+		dev_warn(&adev->dev, "requested TX FIFO threshold %u, adjusted down to %u\n",
+			 dev->tft, max_fifo_threshold);
+		dev->tft = max_fifo_threshold;
+	}
+
+	if (dev->rft > max_fifo_threshold) {
+		dev_warn(&adev->dev, "requested RX FIFO threshold %u, adjusted down to %u\n",
+			dev->rft, max_fifo_threshold);
+		dev->rft = max_fifo_threshold;
+	}
+
+	amba_set_drvdata(adev, dev);
+
+	dev->virtbase = devm_ioremap(&adev->dev, adev->res.start,
+				resource_size(&adev->res));
+	if (!dev->virtbase) {
+		ret = -ENOMEM;
+		goto err_no_mem;
+	}
+
+	dev->irq = adev->irq[0];
+	ret = devm_request_irq(&adev->dev, dev->irq, i2c_irq_handler, 0,
+				DRIVER_NAME, dev);
+	if (ret) {
+		dev_err(&adev->dev, "cannot claim the irq %d\n", dev->irq);
+		goto err_no_mem;
+	}
+
+	pm_suspend_ignore_children(&adev->dev, true);
+
+	dev->clk = devm_clk_get(&adev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(&adev->dev, "could not get i2c clock\n");
+		ret = PTR_ERR(dev->clk);
+		goto err_no_mem;
+	}
+
+	ret = clk_prepare_enable(dev->clk);
+	if (ret) {
+		dev_err(&adev->dev, "can't prepare_enable clock\n");
+		goto err_no_mem;
+	}
+
+	init_hw(dev);
+
+	adap = &dev->adap;
+	adap->dev.of_node = np;
+	adap->dev.parent = &adev->dev;
+	adap->owner = THIS_MODULE;
+	adap->class = I2C_CLASS_DEPRECATED;
+	adap->algo = &nmk_i2c_algo;
+	adap->timeout = msecs_to_jiffies(dev->timeout);
+	snprintf(adap->name, sizeof(adap->name),
+		 "Nomadik I2C at %pR", &adev->res);
+
+	i2c_set_adapdata(adap, dev);
+
+	dev_info(&adev->dev,
+		 "initialize %s on virtual base %p\n",
+		 adap->name, dev->virtbase);
+
+	ret = i2c_add_adapter(adap);
+	if (ret) {
+		dev_err(&adev->dev, "failed to add adapter\n");
+		goto err_no_adap;
+	}
+
+	pm_runtime_put(&adev->dev);
+
+	return 0;
+
+ err_no_adap:
+	clk_disable_unprepare(dev->clk);
+ err_no_mem:
+
+	return ret;
+}
+
+static int nmk_i2c_remove(struct amba_device *adev)
+{
+	struct resource *res = &adev->res;
+	struct nmk_i2c_dev *dev = amba_get_drvdata(adev);
+
+	i2c_del_adapter(&dev->adap);
+	flush_i2c_fifo(dev);
+	disable_all_interrupts(dev);
+	clear_all_interrupts(dev);
+	/* disable the controller */
+	i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
+	clk_disable_unprepare(dev->clk);
+	if (res)
+		release_mem_region(res->start, resource_size(res));
+
+	return 0;
+}
+
+static struct i2c_vendor_data vendor_stn8815 = {
+	.has_mtdws = false,
+	.fifodepth = 16, /* Guessed from TFTR/RFTR = 7 */
+};
+
+static struct i2c_vendor_data vendor_db8500 = {
+	.has_mtdws = true,
+	.fifodepth = 32, /* Guessed from TFTR/RFTR = 15 */
+};
+
+static struct amba_id nmk_i2c_ids[] = {
+	{
+		.id	= 0x00180024,
+		.mask	= 0x00ffffff,
+		.data	= &vendor_stn8815,
+	},
+	{
+		.id	= 0x00380024,
+		.mask	= 0x00ffffff,
+		.data	= &vendor_db8500,
+	},
+	{},
+};
+
+MODULE_DEVICE_TABLE(amba, nmk_i2c_ids);
+
+static struct amba_driver nmk_i2c_driver = {
+	.drv = {
+		.owner = THIS_MODULE,
+		.name = DRIVER_NAME,
+		.pm = &nmk_i2c_pm,
+	},
+	.id_table = nmk_i2c_ids,
+	.probe = nmk_i2c_probe,
+	.remove = nmk_i2c_remove,
+};
+
+static int __init nmk_i2c_init(void)
+{
+	return amba_driver_register(&nmk_i2c_driver);
+}
+
+static void __exit nmk_i2c_exit(void)
+{
+	amba_driver_unregister(&nmk_i2c_driver);
+}
+
+subsys_initcall(nmk_i2c_init);
+module_exit(nmk_i2c_exit);
+
+MODULE_AUTHOR("Sachin Verma, Srinidhi KASAGAR");
+MODULE_DESCRIPTION("Nomadik/Ux500 I2C driver");
+MODULE_LICENSE("GPL");