From f17e50f67fa3c77624edf2ca03fae0d50f0ce39b Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Thu, 7 Aug 2014 18:26:42 +0200
Subject: [PATCH 31/36] I2C: MIPS: lantiq: add FALC-ON i2c bus master

This patch adds the driver needed to make the I2C bus work on FALC-ON SoCs.

Signed-off-by: Thomas Langer <thomas.langer@lantiq.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
---
 drivers/i2c/busses/Kconfig      |   10 +
 drivers/i2c/busses/Makefile     |    1 +
 drivers/i2c/busses/i2c-lantiq.c |  747 +++++++++++++++++++++++++++++++++++++++
 drivers/i2c/busses/i2c-lantiq.h |  234 ++++++++++++
 4 files changed, 992 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-lantiq.c
 create mode 100644 drivers/i2c/busses/i2c-lantiq.h

--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -729,6 +729,16 @@ config I2C_MESON
 	  If you say yes to this option, support will be included for the
 	  I2C interface on the Amlogic Meson family of SoCs.
 
+config I2C_LANTIQ
+	tristate "Lantiq I2C interface"
+	depends on LANTIQ && SOC_FALCON
+	help
+	  If you say yes to this option, support will be included for the
+	  Lantiq I2C core.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-lantiq.
+
 config I2C_MPC
 	tristate "MPC107/824x/85xx/512x/52xx/83xx/86xx"
 	depends on PPC
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_I2C_IMX_LPI2C)	+= i2c-imx-l
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
+obj-$(CONFIG_I2C_LANTIQ)	+= i2c-lantiq.o
 obj-$(CONFIG_I2C_LPC2K)		+= i2c-lpc2k.o
 obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
--- /dev/null
+++ b/drivers/i2c/busses/i2c-lantiq.c
@@ -0,0 +1,747 @@
+
+/*
+ * Lantiq I2C bus adapter
+ *
+ * Parts based on i2c-designware.c and other i2c drivers from Linux 2.6.33
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Copyright (C) 2012 Thomas Langer <thomas.langer@lantiq.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h> /* for kzalloc, kfree */
+#include <linux/i2c.h>
+#include <linux/errno.h>
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/of_irq.h>
+
+#include <lantiq_soc.h>
+#include "i2c-lantiq.h"
+
+/*
+ * CURRENT ISSUES:
+ * - no high speed support
+ * - ten bit mode is not tested (no slave devices)
+ */
+
+/* access macros */
+#define i2c_r32(reg)	\
+	__raw_readl(&(priv->membase)->reg)
+#define i2c_w32(val, reg)	\
+	__raw_writel(val, &(priv->membase)->reg)
+#define i2c_w32_mask(clear, set, reg)	\
+	i2c_w32((i2c_r32(reg) & ~(clear)) | (set), reg)
+
+#define DRV_NAME "i2c-lantiq"
+#define DRV_VERSION "1.00"
+
+#define LTQ_I2C_BUSY_TIMEOUT		20 /* ms */
+
+#ifdef DEBUG
+#define LTQ_I2C_XFER_TIMEOUT		(25*HZ)
+#else
+#define LTQ_I2C_XFER_TIMEOUT		HZ
+#endif
+
+#define LTQ_I2C_IMSC_DEFAULT_MASK	(I2C_IMSC_I2C_P_INT_EN | \
+					 I2C_IMSC_I2C_ERR_INT_EN)
+
+#define LTQ_I2C_ARB_LOST		(1 << 0)
+#define LTQ_I2C_NACK			(1 << 1)
+#define LTQ_I2C_RX_UFL			(1 << 2)
+#define LTQ_I2C_RX_OFL			(1 << 3)
+#define LTQ_I2C_TX_UFL			(1 << 4)
+#define LTQ_I2C_TX_OFL			(1 << 5)
+
+struct ltq_i2c {
+	struct mutex mutex;
+
+
+	/* active clock settings */
+	unsigned int input_clock;	/* clock input for i2c hardware block */
+	unsigned int i2c_clock;		/* approximated bus clock in kHz */
+
+	struct clk *clk_gate;
+	struct clk *clk_input;
+
+
+	/* resources (memory and interrupts) */
+	int irq_lb;				/* last burst irq */
+
+	struct lantiq_reg_i2c __iomem *membase;	/* base of mapped registers */
+
+	struct i2c_adapter adap;
+	struct device *dev;
+
+	struct completion cmd_complete;
+
+
+	/* message transfer data */
+	struct i2c_msg *current_msg;	/* current message */
+	int msgs_num;		/* number of messages to handle */
+	u8 *msg_buf;		/* current buffer */
+	u32 msg_buf_len;	/* remaining length of current buffer */
+	int msg_err;		/* error status of the current transfer */
+
+
+	/* master status codes */
+	enum {
+		STATUS_IDLE,
+		STATUS_ADDR,	/* address phase */
+		STATUS_WRITE,
+		STATUS_READ,
+		STATUS_READ_END,
+		STATUS_STOP
+	} status;
+};
+
+static irqreturn_t ltq_i2c_isr(int irq, void *dev_id);
+
+static inline void enable_burst_irq(struct ltq_i2c *priv)
+{
+	i2c_w32_mask(0, I2C_IMSC_LBREQ_INT_EN | I2C_IMSC_BREQ_INT_EN, imsc);
+}
+static inline void disable_burst_irq(struct ltq_i2c *priv)
+{
+	i2c_w32_mask(I2C_IMSC_LBREQ_INT_EN | I2C_IMSC_BREQ_INT_EN, 0, imsc);
+}
+
+static void prepare_msg_send_addr(struct ltq_i2c *priv)
+{
+	struct i2c_msg *msg = priv->current_msg;
+	int rd = !!(msg->flags & I2C_M_RD);	/* extends to 0 or 1 */
+	u16 addr = msg->addr;
+
+	/* new i2c_msg */
+	priv->msg_buf = msg->buf;
+	priv->msg_buf_len = msg->len;
+	if (rd)
+		priv->status = STATUS_READ;
+	else
+		priv->status = STATUS_WRITE;
+
+	/* send slave address */
+	if (msg->flags & I2C_M_TEN) {
+		i2c_w32(0xf0 | ((addr & 0x300) >> 7) | rd, txd);
+		i2c_w32(addr & 0xff, txd);
+	} else {
+		i2c_w32((addr & 0x7f) << 1 | rd, txd);
+	}
+}
+
+static void ltq_i2c_set_tx_len(struct ltq_i2c *priv)
+{
+	struct i2c_msg *msg = priv->current_msg;
+	int len = (msg->flags & I2C_M_TEN) ? 2 : 1;
+
+	pr_debug("set_tx_len %cX\n", (msg->flags & I2C_M_RD) ? 'R' : 'T');
+
+	priv->status = STATUS_ADDR;
+
+	if (!(msg->flags & I2C_M_RD))
+		len += msg->len;
+	else
+		/* set maximum received packet size (before rx int!) */
+		i2c_w32(msg->len, mrps_ctrl);
+	i2c_w32(len, tps_ctrl);
+	enable_burst_irq(priv);
+}
+
+static int ltq_i2c_hw_set_clock(struct i2c_adapter *adap)
+{
+	struct ltq_i2c *priv = i2c_get_adapdata(adap);
+	unsigned int input_clock = clk_get_rate(priv->clk_input);
+	u32 dec, inc = 1;
+
+	/* clock changed? */
+	if (priv->input_clock == input_clock)
+		return 0;
+
+	/*
+	 * this formula is only an approximation, found by the recommended
+	 * values in the "I2C Architecture Specification 1.7.1"
+	 */
+	dec = input_clock / (priv->i2c_clock * 2);
+	if (dec <= 6)
+		return -ENXIO;
+
+	i2c_w32(0, fdiv_high_cfg);
+	i2c_w32((inc << I2C_FDIV_CFG_INC_OFFSET) |
+		(dec << I2C_FDIV_CFG_DEC_OFFSET),
+		fdiv_cfg);
+
+	dev_info(priv->dev, "setup clocks (in %d kHz, bus %d kHz, dec=%d)\n",
+		input_clock, priv->i2c_clock, dec);
+
+	priv->input_clock = input_clock;
+	return 0;
+}
+
+static int ltq_i2c_hw_init(struct i2c_adapter *adap)
+{
+	int ret = 0;
+	struct ltq_i2c *priv = i2c_get_adapdata(adap);
+
+	/* disable bus */
+	i2c_w32_mask(I2C_RUN_CTRL_RUN_EN, 0, run_ctrl);
+
+#ifndef DEBUG
+	/* set normal operation clock divider */
+	i2c_w32(1 << I2C_CLC_RMC_OFFSET, clc);
+#else
+	/* for debugging a higher divider value! */
+	i2c_w32(0xF0 << I2C_CLC_RMC_OFFSET, clc);
+#endif
+
+	/* setup clock */
+	ret = ltq_i2c_hw_set_clock(adap);
+	if (ret != 0) {
+		dev_warn(priv->dev, "invalid clock settings\n");
+		return ret;
+	}
+
+	/* configure fifo */
+	i2c_w32(I2C_FIFO_CFG_TXFC | /* tx fifo as flow controller */
+		I2C_FIFO_CFG_RXFC | /* rx fifo as flow controller */
+		I2C_FIFO_CFG_TXFA_TXFA2 | /* tx fifo 4-byte aligned */
+		I2C_FIFO_CFG_RXFA_RXFA2 | /* rx fifo 4-byte aligned */
+		I2C_FIFO_CFG_TXBS_TXBS0 | /* tx fifo burst size is 1 word */
+		I2C_FIFO_CFG_RXBS_RXBS0,  /* rx fifo burst size is 1 word */
+		fifo_cfg);
+
+	/* configure address */
+	i2c_w32(I2C_ADDR_CFG_SOPE_EN |	/* generate stop when no more data in
+					   the fifo */
+		I2C_ADDR_CFG_SONA_EN |	/* generate stop when NA received */
+		I2C_ADDR_CFG_MnS_EN |	/* we are master device */
+		0,			/* our slave address (not used!) */
+		addr_cfg);
+
+	/* enable bus */
+	i2c_w32_mask(0, I2C_RUN_CTRL_RUN_EN, run_ctrl);
+
+	return 0;
+}
+
+static int ltq_i2c_wait_bus_not_busy(struct ltq_i2c *priv)
+{
+	unsigned long timeout;
+
+	timeout = jiffies + msecs_to_jiffies(LTQ_I2C_BUSY_TIMEOUT);
+
+	do {
+		u32 stat = i2c_r32(bus_stat);
+
+		if ((stat & I2C_BUS_STAT_BS_MASK) == I2C_BUS_STAT_BS_FREE)
+			return 0;
+
+		cond_resched();
+	} while (!time_after_eq(jiffies, timeout));
+
+	dev_err(priv->dev, "timeout waiting for bus ready\n");
+	return -ETIMEDOUT;
+}
+
+static void ltq_i2c_tx(struct ltq_i2c *priv, int last)
+{
+	if (priv->msg_buf_len && priv->msg_buf) {
+		i2c_w32(*priv->msg_buf, txd);
+
+		if (--priv->msg_buf_len)
+			priv->msg_buf++;
+		else
+			priv->msg_buf = NULL;
+	} else {
+		last = 1;
+	}
+
+	if (last)
+		disable_burst_irq(priv);
+}
+
+static void ltq_i2c_rx(struct ltq_i2c *priv, int last)
+{
+	u32 fifo_stat, timeout;
+	if (priv->msg_buf_len && priv->msg_buf) {
+		timeout = 5000000;
+		do {
+			fifo_stat = i2c_r32(ffs_stat);
+		} while (!fifo_stat && --timeout);
+		if (!timeout) {
+			last = 1;
+			pr_debug("\nrx timeout\n");
+			goto err;
+		}
+		while (fifo_stat) {
+			*priv->msg_buf = i2c_r32(rxd);
+			if (--priv->msg_buf_len) {
+				priv->msg_buf++;
+			} else {
+				priv->msg_buf = NULL;
+				last = 1;
+				break;
+			}
+			/*
+			 * do not read more than burst size, otherwise no "last
+			 * burst" is generated and the transaction is blocked!
+			 */
+			fifo_stat = 0;
+		}
+	} else {
+		last = 1;
+	}
+err:
+	if (last) {
+		disable_burst_irq(priv);
+
+		if (priv->status == STATUS_READ_END) {
+			/* 
+			 * do the STATUS_STOP and complete() here, as sometimes
+			 * the tx_end is already seen before this is finished
+			 */
+			priv->status = STATUS_STOP;
+			complete(&priv->cmd_complete);
+		} else {
+			i2c_w32(I2C_ENDD_CTRL_SETEND, endd_ctrl);
+			priv->status = STATUS_READ_END;
+		}
+	}
+}
+
+static void ltq_i2c_xfer_init(struct ltq_i2c *priv)
+{
+	/* enable interrupts */
+	i2c_w32(LTQ_I2C_IMSC_DEFAULT_MASK, imsc);
+
+	/* trigger transfer of first msg */
+	ltq_i2c_set_tx_len(priv);
+}
+
+static void dump_msgs(struct i2c_msg msgs[], int num, int rx)
+{
+#if defined(DEBUG)
+	int i, j;
+	pr_debug("Messages %d %s\n", num, rx ? "out" : "in");
+	for (i = 0; i < num; i++) {
+		pr_debug("%2d %cX Msg(%d) addr=0x%X: ", i,
+			(msgs[i].flags & I2C_M_RD) ? 'R' : 'T',
+			msgs[i].len, msgs[i].addr);
+		if (!(msgs[i].flags & I2C_M_RD) || rx) {
+			for (j = 0; j < msgs[i].len; j++)
+				pr_debug("%02X ", msgs[i].buf[j]);
+		}
+		pr_debug("\n");
+	}
+#endif
+}
+
+static void ltq_i2c_release_bus(struct ltq_i2c *priv)
+{
+	if ((i2c_r32(bus_stat) & I2C_BUS_STAT_BS_MASK) == I2C_BUS_STAT_BS_BM)
+		i2c_w32(I2C_ENDD_CTRL_SETEND, endd_ctrl);
+}
+
+static int ltq_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+			   int num)
+{
+	struct ltq_i2c *priv = i2c_get_adapdata(adap);
+	int ret;
+
+	dev_dbg(priv->dev, "xfer %u messages\n", num);
+	dump_msgs(msgs, num, 0);
+
+	mutex_lock(&priv->mutex);
+
+	init_completion(&priv->cmd_complete);
+	priv->current_msg = msgs;
+	priv->msgs_num = num;
+	priv->msg_err = 0;
+	priv->status = STATUS_IDLE;
+
+	/* wait for the bus to become ready */
+	ret = ltq_i2c_wait_bus_not_busy(priv);
+	if (ret)
+		goto done;
+
+	while (priv->msgs_num) {
+		/* start the transfers */
+		ltq_i2c_xfer_init(priv);
+
+		/* wait for transfers to complete */
+		ret = wait_for_completion_interruptible_timeout(
+			&priv->cmd_complete, LTQ_I2C_XFER_TIMEOUT);
+		if (ret == 0) {
+			dev_err(priv->dev, "controller timed out\n");
+			ltq_i2c_hw_init(adap);
+			ret = -ETIMEDOUT;
+			goto done;
+		} else if (ret < 0)
+			goto done;
+
+		if (priv->msg_err) {
+			if (priv->msg_err & LTQ_I2C_NACK)
+				ret = -ENXIO;
+			else
+				ret = -EREMOTEIO;
+			goto done;
+		}
+		if (--priv->msgs_num)
+			priv->current_msg++;
+	}
+	/* no error? */
+	ret = num;
+
+done:
+	ltq_i2c_release_bus(priv);
+
+	mutex_unlock(&priv->mutex);
+
+	if (ret >= 0)
+		dump_msgs(msgs, num, 1);
+
+	pr_debug("XFER ret %d\n", ret);
+	return ret;
+}
+
+static irqreturn_t ltq_i2c_isr_burst(int irq, void *dev_id)
+{
+	struct ltq_i2c *priv = dev_id;
+	struct i2c_msg *msg = priv->current_msg;
+	int last = (irq == priv->irq_lb);
+
+	if (last)
+		pr_debug("LB ");
+	else
+		pr_debug("B ");
+
+	if (msg->flags & I2C_M_RD) {
+		switch (priv->status) {
+		case STATUS_ADDR:
+			pr_debug("X");
+			prepare_msg_send_addr(priv);
+			disable_burst_irq(priv);
+			break;
+		case STATUS_READ:
+		case STATUS_READ_END:
+			pr_debug("R");
+			ltq_i2c_rx(priv, last);
+			break;
+		default:
+			disable_burst_irq(priv);
+			pr_warn("Status R %d\n", priv->status);
+			break;
+		}
+	} else {
+		switch (priv->status) {
+		case STATUS_ADDR:
+			pr_debug("x");
+			prepare_msg_send_addr(priv);
+			break;
+		case STATUS_WRITE:
+			pr_debug("w");
+			ltq_i2c_tx(priv, last);
+			break;
+		default:
+			disable_burst_irq(priv);
+			pr_warn("Status W %d\n", priv->status);
+			break;
+		}
+	}
+
+	i2c_w32(I2C_ICR_BREQ_INT_CLR | I2C_ICR_LBREQ_INT_CLR, icr);
+	return IRQ_HANDLED;
+}
+
+static void ltq_i2c_isr_prot(struct ltq_i2c *priv)
+{
+	u32 i_pro = i2c_r32(p_irqss);
+
+	pr_debug("i2c-p");
+
+	/* not acknowledge */
+	if (i_pro & I2C_P_IRQSS_NACK) {
+		priv->msg_err |= LTQ_I2C_NACK;
+		pr_debug(" nack");
+	}
+
+	/* arbitration lost */
+	if (i_pro & I2C_P_IRQSS_AL) {
+		priv->msg_err |= LTQ_I2C_ARB_LOST;
+		pr_debug(" arb-lost");
+	}
+	/* tx -> rx switch */
+	if (i_pro & I2C_P_IRQSS_RX)
+		pr_debug(" rx");
+
+	/* tx end */
+	if (i_pro & I2C_P_IRQSS_TX_END)
+		pr_debug(" txend");
+	pr_debug("\n");
+
+	if (!priv->msg_err) {
+		/* tx -> rx switch */
+		if (i_pro & I2C_P_IRQSS_RX) {
+			priv->status = STATUS_READ;
+			enable_burst_irq(priv);
+		}
+		if (i_pro & I2C_P_IRQSS_TX_END) {
+			if (priv->status == STATUS_READ)
+				priv->status = STATUS_READ_END;
+			else {
+				disable_burst_irq(priv);
+				priv->status = STATUS_STOP;
+			}
+		}
+	}
+
+	i2c_w32(i_pro, p_irqsc);
+}
+
+static irqreturn_t ltq_i2c_isr(int irq, void *dev_id)
+{
+	u32 i_raw, i_err = 0;
+	struct ltq_i2c *priv = dev_id;
+
+	i_raw = i2c_r32(mis);
+	pr_debug("i_raw 0x%08X\n", i_raw);
+
+	/* error interrupt */
+	if (i_raw & I2C_RIS_I2C_ERR_INT_INTOCC) {
+		i_err = i2c_r32(err_irqss);
+		pr_debug("i_err 0x%08X bus_stat 0x%04X\n",
+			i_err, i2c_r32(bus_stat));
+
+		/* tx fifo overflow (8) */
+		if (i_err & I2C_ERR_IRQSS_TXF_OFL)
+			priv->msg_err |= LTQ_I2C_TX_OFL;
+
+		/* tx fifo underflow (4) */
+		if (i_err & I2C_ERR_IRQSS_TXF_UFL)
+			priv->msg_err |= LTQ_I2C_TX_UFL;
+
+		/* rx fifo overflow (2) */
+		if (i_err & I2C_ERR_IRQSS_RXF_OFL)
+			priv->msg_err |= LTQ_I2C_RX_OFL;
+
+		/* rx fifo underflow (1) */
+		if (i_err & I2C_ERR_IRQSS_RXF_UFL)
+			priv->msg_err |= LTQ_I2C_RX_UFL;
+
+		i2c_w32(i_err, err_irqsc);
+	}
+
+	/* protocol interrupt */
+	if (i_raw & I2C_RIS_I2C_P_INT_INTOCC)
+		ltq_i2c_isr_prot(priv);
+
+	if ((priv->msg_err) || (priv->status == STATUS_STOP))
+		complete(&priv->cmd_complete);
+
+	return IRQ_HANDLED;
+}
+
+static u32 ltq_i2c_functionality(struct i2c_adapter *adap)
+{
+	return	I2C_FUNC_I2C |
+		I2C_FUNC_10BIT_ADDR |
+		I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm ltq_i2c_algorithm = {
+	.master_xfer	= ltq_i2c_xfer,
+	.functionality	= ltq_i2c_functionality,
+};
+
+static int ltq_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct ltq_i2c *priv;
+	struct i2c_adapter *adap;
+	struct resource *mmres, irqres[4];
+	int ret = 0;
+
+	dev_dbg(&pdev->dev, "probing\n");
+
+	mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ret = of_irq_to_resource_table(node, irqres, 4);
+	if (!mmres || (ret != 4)) {
+		dev_err(&pdev->dev, "no resources\n");
+		return -ENODEV;
+	}
+
+	/* allocate private data */
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(&pdev->dev, "can't allocate private data\n");
+		return -ENOMEM;
+	}
+
+	adap = &priv->adap;
+	i2c_set_adapdata(adap, priv);
+	adap->owner = THIS_MODULE;
+	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	strlcpy(adap->name, DRV_NAME "-adapter", sizeof(adap->name));
+	adap->algo = &ltq_i2c_algorithm;
+	adap->dev.parent = &pdev->dev;
+	adap->dev.of_node = pdev->dev.of_node;
+
+	if (of_property_read_u32(node, "clock-frequency", &priv->i2c_clock)) {
+		dev_warn(&pdev->dev, "No I2C speed selected, using 100kHz\n");
+		priv->i2c_clock = 100000;
+	}
+
+	init_completion(&priv->cmd_complete);
+	mutex_init(&priv->mutex);
+
+	priv->membase = devm_ioremap_resource(&pdev->dev, mmres);
+	if (IS_ERR(priv->membase))
+		return PTR_ERR(priv->membase);
+
+	priv->dev = &pdev->dev;
+	priv->irq_lb = irqres[0].start;
+
+	ret = devm_request_irq(&pdev->dev, irqres[0].start, ltq_i2c_isr_burst,
+		0x0, "i2c lb", priv);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get last burst IRQ %d\n",
+			irqres[0].start);
+		return -ENODEV;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irqres[1].start, ltq_i2c_isr_burst,
+		0x0, "i2c b", priv);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get burst IRQ %d\n",
+			irqres[1].start);
+		return -ENODEV;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irqres[2].start, ltq_i2c_isr,
+		0x0, "i2c err", priv);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get error IRQ %d\n",
+			irqres[2].start);
+		return -ENODEV;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irqres[3].start, ltq_i2c_isr,
+		0x0, "i2c p", priv);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get protocol IRQ %d\n",
+			irqres[3].start);
+		return -ENODEV;
+	}
+
+	dev_dbg(&pdev->dev, "mapped io-space to %p\n", priv->membase);
+	dev_dbg(&pdev->dev, "use IRQs %d, %d, %d, %d\n", irqres[0].start,
+		irqres[1].start, irqres[2].start, irqres[3].start);
+
+	priv->clk_gate = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk_gate)) {
+		dev_err(&pdev->dev, "failed to get i2c clk\n");
+		return -ENOENT;
+	}
+
+	/* this is a static clock, which has no refcounting */
+	priv->clk_input = clk_get_fpi();
+	if (IS_ERR(priv->clk_input)) {
+		dev_err(&pdev->dev, "failed to get fpi clk\n");
+		return -ENOENT;
+	}
+
+	clk_activate(priv->clk_gate);
+
+	/* add our adapter to the i2c stack */
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret) {
+		dev_err(&pdev->dev, "can't register I2C adapter\n");
+		goto out;
+	}
+
+	platform_set_drvdata(pdev, priv);
+	i2c_set_adapdata(adap, priv);
+
+	/* print module version information */
+	dev_dbg(&pdev->dev, "module id=%u revision=%u\n",
+		(i2c_r32(id) & I2C_ID_ID_MASK) >> I2C_ID_ID_OFFSET,
+		(i2c_r32(id) & I2C_ID_REV_MASK) >> I2C_ID_REV_OFFSET);
+
+	/* initialize HW */
+	ret = ltq_i2c_hw_init(adap);
+	if (ret) {
+		dev_err(&pdev->dev, "can't configure adapter\n");
+		i2c_del_adapter(adap);
+		platform_set_drvdata(pdev, NULL);
+		goto out;
+	} else {
+		dev_info(&pdev->dev, "version %s\n", DRV_VERSION);
+	}
+
+out:
+	/* if init failed, we need to deactivate the clock gate */
+	if (ret)
+		clk_deactivate(priv->clk_gate);
+
+	return ret;
+}
+
+static int ltq_i2c_remove(struct platform_device *pdev)
+{
+	struct ltq_i2c *priv = platform_get_drvdata(pdev);
+
+	/* disable bus */
+	i2c_w32_mask(I2C_RUN_CTRL_RUN_EN, 0, run_ctrl);
+
+	/* power down the core */
+	clk_deactivate(priv->clk_gate);
+
+	/* remove driver */
+	i2c_del_adapter(&priv->adap);
+	kfree(priv);
+
+	dev_dbg(&pdev->dev, "removed\n");
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+static const struct of_device_id ltq_i2c_match[] = {
+	{ .compatible = "lantiq,lantiq-i2c" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltq_i2c_match);
+
+static struct platform_driver ltq_i2c_driver = {
+	.probe	= ltq_i2c_probe,
+	.remove	= ltq_i2c_remove,
+	.driver	= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+		.of_match_table = ltq_i2c_match,
+	},
+};
+
+module_platform_driver(ltq_i2c_driver);
+
+MODULE_DESCRIPTION("Lantiq I2C bus adapter");
+MODULE_AUTHOR("Thomas Langer <thomas.langer@lantiq.com>");
+MODULE_ALIAS("platform:" DRV_NAME);
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
--- /dev/null
+++ b/drivers/i2c/busses/i2c-lantiq.h
@@ -0,0 +1,234 @@
+#ifndef I2C_LANTIQ_H
+#define I2C_LANTIQ_H
+
+/* I2C register structure */
+struct lantiq_reg_i2c {
+	/* I2C Kernel Clock Control Register */
+	unsigned int clc; /* 0x00000000 */
+	/* Reserved */
+	unsigned int res_0; /* 0x00000004 */
+	/* I2C Identification Register */
+	unsigned int id; /* 0x00000008 */
+	/* Reserved */
+	unsigned int res_1; /* 0x0000000C */
+	/*
+	 * I2C RUN Control Register
+	 * This register enables and disables the I2C peripheral. Before
+	 * enabling, the I2C has to be configured properly. After enabling
+	 * no configuration is possible
+	 */
+	unsigned int run_ctrl; /* 0x00000010 */
+	/*
+	 * I2C End Data Control Register
+	 * This register is used to either turn around the data transmission
+	 * direction or to address another slave without sending a stop
+	 * condition. Also the software can stop the slave-transmitter by
+	 * sending a not-accolade when working as master-receiver or even
+	 * stop data transmission immediately when operating as
+	 * master-transmitter. The writing to the bits of this control
+	 * register is only effective when in MASTER RECEIVES BYTES, MASTER
+	 * TRANSMITS BYTES, MASTER RESTART or SLAVE RECEIVE BYTES state
+	 */
+	unsigned int endd_ctrl; /* 0x00000014 */
+	/*
+	 * I2C Fractional Divider Configuration Register
+	 * These register is used to program the fractional divider of the I2C
+	 * bus. Before the peripheral is switched on by setting the RUN-bit the
+	 * two (fixed) values for the two operating frequencies are programmed
+	 * into these (configuration) registers. The Register FDIV_HIGH_CFG has
+	 * the same layout as I2C_FDIV_CFG.
+	 */
+	unsigned int fdiv_cfg; /* 0x00000018 */
+	/*
+	 * I2C Fractional Divider (highspeed mode) Configuration Register
+	 * These register is used to program the fractional divider of the I2C
+	 * bus. Before the peripheral is switched on by setting the RUN-bit the
+	 * two (fixed) values for the two operating frequencies are programmed
+	 * into these (configuration) registers. The Register FDIV_CFG has the
+	 * same layout as I2C_FDIV_CFG.
+	 */
+	unsigned int fdiv_high_cfg; /* 0x0000001C */
+	/* I2C Address Configuration Register */
+	unsigned int addr_cfg; /* 0x00000020 */
+	/* I2C Bus Status Register
+	 * This register gives a status information of the I2C. This additional
+	 * information can be used by the software to start proper actions.
+	 */
+	unsigned int bus_stat; /* 0x00000024 */
+	/* I2C FIFO Configuration Register */
+	unsigned int fifo_cfg; /* 0x00000028 */
+	/* I2C Maximum Received Packet Size Register */
+	unsigned int mrps_ctrl; /* 0x0000002C */
+	/* I2C Received Packet Size Status Register */
+	unsigned int rps_stat; /* 0x00000030 */
+	/* I2C Transmit Packet Size Register */
+	unsigned int tps_ctrl; /* 0x00000034 */
+	/* I2C Filled FIFO Stages Status Register */
+	unsigned int ffs_stat; /* 0x00000038 */
+	/* Reserved */
+	unsigned int res_2; /* 0x0000003C */
+	/* I2C Timing Configuration Register */
+	unsigned int tim_cfg; /* 0x00000040 */
+	/* Reserved */
+	unsigned int res_3[7]; /* 0x00000044 */
+	/* I2C Error Interrupt Request Source Mask Register */
+	unsigned int err_irqsm; /* 0x00000060 */
+	/* I2C Error Interrupt Request Source Status Register */
+	unsigned int err_irqss; /* 0x00000064 */
+	/* I2C Error Interrupt Request Source Clear Register */
+	unsigned int err_irqsc; /* 0x00000068 */
+	/* Reserved */
+	unsigned int res_4; /* 0x0000006C */
+	/* I2C Protocol Interrupt Request Source Mask Register */
+	unsigned int p_irqsm; /* 0x00000070 */
+	/* I2C Protocol Interrupt Request Source Status Register */
+	unsigned int p_irqss; /* 0x00000074 */
+	/* I2C Protocol Interrupt Request Source Clear Register */
+	unsigned int p_irqsc; /* 0x00000078 */
+	/* Reserved */
+	unsigned int res_5; /* 0x0000007C */
+	/* I2C Raw Interrupt Status Register */
+	unsigned int ris; /* 0x00000080 */
+	/* I2C Interrupt Mask Control Register */
+	unsigned int imsc; /* 0x00000084 */
+	/* I2C Masked Interrupt Status Register */
+	unsigned int mis; /* 0x00000088 */
+	/* I2C Interrupt Clear Register */
+	unsigned int icr; /* 0x0000008C */
+	/* I2C Interrupt Set Register */
+	unsigned int isr; /* 0x00000090 */
+	/* I2C DMA Enable Register */
+	unsigned int dmae; /* 0x00000094 */
+	/* Reserved */
+	unsigned int res_6[8154]; /* 0x00000098 */
+	/* I2C Transmit Data Register */
+	unsigned int txd; /* 0x00008000 */
+	/* Reserved */
+	unsigned int res_7[4095]; /* 0x00008004 */
+	/* I2C Receive Data Register */
+	unsigned int rxd; /* 0x0000C000 */
+	/* Reserved */
+	unsigned int res_8[4095]; /* 0x0000C004 */
+};
+
+/*
+ * Clock Divider for Normal Run Mode
+ * Max 8-bit divider value. IF RMC is 0 the module is disabled. Note: As long
+ * as the new divider value RMC is not valid, the register returns 0x0000 00xx
+ * on reading.
+ */
+#define I2C_CLC_RMC_MASK 0x0000FF00
+/* field offset */
+#define I2C_CLC_RMC_OFFSET 8
+
+/* Fields of "I2C Identification Register" */
+/* Module ID */
+#define I2C_ID_ID_MASK 0x0000FF00
+/* field offset */
+#define I2C_ID_ID_OFFSET 8
+/* Revision */
+#define I2C_ID_REV_MASK 0x000000FF
+/* field offset */
+#define I2C_ID_REV_OFFSET 0
+
+/* Fields of "I2C Interrupt Mask Control Register" */
+/* Enable */
+#define I2C_IMSC_BREQ_INT_EN 0x00000008
+/* Enable */
+#define I2C_IMSC_LBREQ_INT_EN 0x00000004
+
+/* Fields of "I2C Fractional Divider Configuration Register" */
+/* field offset */
+#define I2C_FDIV_CFG_INC_OFFSET 16
+
+/* Fields of "I2C Interrupt Mask Control Register" */
+/* Enable */
+#define I2C_IMSC_I2C_P_INT_EN 0x00000020
+/* Enable */
+#define I2C_IMSC_I2C_ERR_INT_EN 0x00000010
+
+/* Fields of "I2C Error Interrupt Request Source Status Register" */
+/* TXF_OFL */
+#define I2C_ERR_IRQSS_TXF_OFL 0x00000008
+/* TXF_UFL */
+#define I2C_ERR_IRQSS_TXF_UFL 0x00000004
+/* RXF_OFL */
+#define I2C_ERR_IRQSS_RXF_OFL 0x00000002
+/* RXF_UFL */
+#define I2C_ERR_IRQSS_RXF_UFL 0x00000001
+
+/* Fields of "I2C Raw Interrupt Status Register" */
+/* Read: Interrupt occurred. */
+#define I2C_RIS_I2C_ERR_INT_INTOCC 0x00000010
+/* Read: Interrupt occurred. */
+#define I2C_RIS_I2C_P_INT_INTOCC 0x00000020
+
+/* Fields of "I2C FIFO Configuration Register" */
+/* TX FIFO Flow Control */
+#define I2C_FIFO_CFG_TXFC 0x00020000
+/* RX FIFO Flow Control */
+#define I2C_FIFO_CFG_RXFC 0x00010000
+/* Word aligned (character alignment of four characters) */
+#define I2C_FIFO_CFG_TXFA_TXFA2 0x00002000
+/* Word aligned (character alignment of four characters) */
+#define I2C_FIFO_CFG_RXFA_RXFA2 0x00000200
+/* 1 word */
+#define I2C_FIFO_CFG_TXBS_TXBS0 0x00000000
+
+/* Fields of "I2C FIFO Configuration Register" */
+/* 1 word */
+#define I2C_FIFO_CFG_RXBS_RXBS0 0x00000000
+/* Stop on Packet End Enable */
+#define I2C_ADDR_CFG_SOPE_EN 0x00200000
+/* Stop on Not Acknowledge Enable */
+#define I2C_ADDR_CFG_SONA_EN 0x00100000
+/* Enable */
+#define I2C_ADDR_CFG_MnS_EN 0x00080000
+
+/* Fields of "I2C Interrupt Clear Register" */
+/* Clear */
+#define I2C_ICR_BREQ_INT_CLR 0x00000008
+/* Clear */
+#define I2C_ICR_LBREQ_INT_CLR 0x00000004
+
+/* Fields of "I2C Fractional Divider Configuration Register" */
+/* field offset */
+#define I2C_FDIV_CFG_DEC_OFFSET 0
+
+/* Fields of "I2C Bus Status Register" */
+/* Bus Status */
+#define I2C_BUS_STAT_BS_MASK 0x00000003
+/* Read from I2C Bus. */
+#define I2C_BUS_STAT_RNW_READ 0x00000004
+/* I2C Bus is free. */
+#define I2C_BUS_STAT_BS_FREE 0x00000000
+/*
+ * The device is working as master and has claimed the control on the
+ * I2C-bus (busy master).
+ */
+#define I2C_BUS_STAT_BS_BM 0x00000002
+
+/* Fields of "I2C RUN Control Register" */
+/* Enable */
+#define I2C_RUN_CTRL_RUN_EN 0x00000001
+
+/* Fields of "I2C End Data Control Register" */
+/*
+ * Set End of Transmission
+ * Note:Do not write '1' to this bit when bus is free. This will cause an
+ * abort after the first byte when a new transfer is started.
+ */
+#define I2C_ENDD_CTRL_SETEND 0x00000002
+
+/* Fields of "I2C Protocol Interrupt Request Source Status Register" */
+/* NACK */
+#define I2C_P_IRQSS_NACK 0x00000010
+/* AL */
+#define I2C_P_IRQSS_AL 0x00000008
+/* RX */
+#define I2C_P_IRQSS_RX 0x00000040
+/* TX_END */
+#define I2C_P_IRQSS_TX_END 0x00000020
+
+
+#endif /* I2C_LANTIQ_H */