[PATCH v3] i2c: Add support for Xilinx XPS IIC Bus Interface

* [PATCH v3] i2c: Add support for Xilinx XPS IIC Bus Interface
@ 2009-09-23 12:49 Richard Röjfors
       [not found] ` <4ABA196D.6070206-l7gf1WXxx3uGw+nKnLezzg@public.gmane.org>
  0 siblings, 1 reply; 3+ messages in thread
From: Richard Röjfors @ 2009-09-23 12:49 UTC (permalink / raw)
  To: linux-i2c-u79uwXL29TY76Z2rM5mHXA; +Cc: Jean Delvare, Ben Dooks

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 8206442..155f200 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -547,6 +547,16 @@ config I2C_VERSATILE
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-versatile.

+config I2C_XILINX
+	tristate "Xilinx I2C Controller"
+	depends on EXPERIMENTAL && HAS_IOMEM
+	help
+	  If you say yes to this option, support will be included for the
+	  Xilinx I2C controller.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called xilinx_i2c.
+
 comment "External I2C/SMBus adapter drivers"

 config I2C_PARPORT
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index e654263..c2907b9 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_I2C_SH_MOBILE)	+= i2c-sh_mobile.o
 obj-$(CONFIG_I2C_SIMTEC)	+= i2c-simtec.o
 obj-$(CONFIG_I2C_STU300)	+= i2c-stu300.o
 obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o
+obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o

 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o
diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
new file mode 100644
index 0000000..561c4cf
--- /dev/null
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -0,0 +1,802 @@
+/*
+ * i2c-xiic.c
+ * Copyright (c) 2009 Intel Corporation
+ *
+ * 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.
+ *
+ * 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.
+ */
+
+/* Supports:
+ * Xilinx IIC
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/wait.h>
+#include <linux/i2c-xiic.h>
+#include <linux/io.h>
+
+#define DRIVER_NAME "xiic-i2c"
+
+enum xilinx_i2c_state {
+	STATE_DONE,
+	STATE_ERROR,
+	STATE_START
+};
+
+struct xiic_i2c {
+	void __iomem		*base;	/* Memory base of the HW registers */
+	wait_queue_head_t	wait;	/* wait queue for callers */
+	struct i2c_adapter	adap;	/* kernel adapter representation */
+	struct i2c_msg		*tx_msg;/* Messages from above to send */
+	spinlock_t		lock;	/* mutual exclusion */
+	unsigned int 		tx_pos;	/* Current pos in TX message */
+	unsigned int		nmsgs;	/* number of messages in tx_msg */
+	enum xilinx_i2c_state	state;	/* see STATE_ */
+	struct i2c_msg		*rx_msg;/* current RX message */
+	int			rx_pos;	/* position within current RX message */
+};
+
+
+#define XIIC_MSB_OFFSET 0
+#define XIIC_REG_OFFSET (0x100+XIIC_MSB_OFFSET)
+
+/*
+ * Register offsets in bytes from RegisterBase. Three is added to the
+ * base offset to access LSB (IBM style) of the word
+ */
+#define XIIC_CR_REG_OFFSET   (0x00+XIIC_REG_OFFSET)	/* Control Register   */
+#define XIIC_SR_REG_OFFSET   (0x04+XIIC_REG_OFFSET)	/* Status Register    */
+#define XIIC_DTR_REG_OFFSET  (0x08+XIIC_REG_OFFSET)	/* Data Tx Register   */
+#define XIIC_DRR_REG_OFFSET  (0x0C+XIIC_REG_OFFSET)	/* Data Rx Register   */
+#define XIIC_ADR_REG_OFFSET  (0x10+XIIC_REG_OFFSET)	/* Address Register   */
+#define XIIC_TFO_REG_OFFSET  (0x14+XIIC_REG_OFFSET)	/* Tx FIFO Occupancy  */
+#define XIIC_RFO_REG_OFFSET  (0x18+XIIC_REG_OFFSET)	/* Rx FIFO Occupancy  */
+#define XIIC_TBA_REG_OFFSET  (0x1C+XIIC_REG_OFFSET)	/* 10 Bit Address reg */
+#define XIIC_RFD_REG_OFFSET  (0x20+XIIC_REG_OFFSET)	/* Rx FIFO Depth reg  */
+#define XIIC_GPO_REG_OFFSET  (0x24+XIIC_REG_OFFSET)	/* Output Register    */
+
+/* Control Register masks */
+#define XIIC_CR_ENABLE_DEVICE_MASK        0x01	/* Device enable = 1      */
+#define XIIC_CR_TX_FIFO_RESET_MASK        0x02	/* Transmit FIFO reset=1  */
+#define XIIC_CR_MSMS_MASK                 0x04	/* Master starts Txing=1  */
+#define XIIC_CR_DIR_IS_TX_MASK            0x08	/* Dir of tx. Txing=1     */
+#define XIIC_CR_NO_ACK_MASK               0x10	/* Tx Ack. NO ack = 1     */
+#define XIIC_CR_REPEATED_START_MASK       0x20	/* Repeated start = 1     */
+#define XIIC_CR_GENERAL_CALL_MASK         0x40	/* Gen Call enabled = 1   */
+
+/* Status Register masks */
+#define XIIC_SR_GEN_CALL_MASK             0x01	/* 1=a mstr issued a GC   */
+#define XIIC_SR_ADDR_AS_SLAVE_MASK        0x02	/* 1=when addr as slave   */
+#define XIIC_SR_BUS_BUSY_MASK             0x04	/* 1 = bus is busy        */
+#define XIIC_SR_MSTR_RDING_SLAVE_MASK     0x08	/* 1=Dir: mstr <-- slave  */
+#define XIIC_SR_TX_FIFO_FULL_MASK         0x10	/* 1 = Tx FIFO full       */
+#define XIIC_SR_RX_FIFO_FULL_MASK         0x20	/* 1 = Rx FIFO full       */
+#define XIIC_SR_RX_FIFO_EMPTY_MASK        0x40	/* 1 = Rx FIFO empty      */
+#define XIIC_SR_TX_FIFO_EMPTY_MASK        0x80	/* 1 = Tx FIFO empty      */
+
+/* Interrupt Status Register masks    Interrupt occurs when...       */
+#define XIIC_INTR_ARB_LOST_MASK           0x01	/* 1 = arbitration lost   */
+#define XIIC_INTR_TX_ERROR_MASK           0x02	/* 1=Tx error/msg complete */
+#define XIIC_INTR_TX_EMPTY_MASK           0x04	/* 1 = Tx FIFO/reg empty  */
+#define XIIC_INTR_RX_FULL_MASK            0x08	/* 1=Rx FIFO/reg=OCY level */
+#define XIIC_INTR_BNB_MASK                0x10	/* 1 = Bus not busy       */
+#define XIIC_INTR_AAS_MASK                0x20	/* 1 = when addr as slave */
+#define XIIC_INTR_NAAS_MASK               0x40	/* 1 = not addr as slave  */
+#define XIIC_INTR_TX_HALF_MASK            0x80	/* 1 = TX FIFO half empty */
+
+/* The following constants specify the depth of the FIFOs */
+#define IIC_RX_FIFO_DEPTH         16	/* Rx fifo capacity               */
+#define IIC_TX_FIFO_DEPTH         16	/* Tx fifo capacity               */
+
+/* The following constants specify groups of interrupts that are typically
+ * enabled or disables at the same time
+ */
+#define XIIC_TX_INTERRUPTS                           \
+(XIIC_INTR_TX_ERROR_MASK | XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)
+
+#define XIIC_TX_RX_INTERRUPTS (XIIC_INTR_RX_FULL_MASK | XIIC_TX_INTERRUPTS)
+
+/* The following constants are used with the following macros to specify the
+ * operation, a read or write operation.
+ */
+#define XIIC_READ_OPERATION  1
+#define XIIC_WRITE_OPERATION 0
+
+/*
+ * Tx Fifo upper bit masks.
+ */
+#define XIIC_TX_DYN_START_MASK            0x0100 /* 1 = Set dynamic start */
+#define XIIC_TX_DYN_STOP_MASK             0x0200 /* 1 = Set dynamic stop */
+
+/*
+ * The following constants define the register offsets for the Interrupt
+ * registers. There are some holes in the memory map for reserved addresses
+ * to allow other registers to be added and still match the memory map of the
+ * interrupt controller registers
+ */
+#define XIIC_DGIER_OFFSET    0x1C /* Device Global Interrupt Enable Register */
+#define XIIC_IISR_OFFSET     0x20 /* Interrupt Status Register */
+#define XIIC_IIER_OFFSET     0x28 /* Interrupt Enable Register */
+#define XIIC_RESETR_OFFSET   0x40 /* Reset Register */
+
+#define XIIC_RESET_MASK             0xAUL
+
+/*
+ * The following constant is used for the device global interrupt enable
+ * register, to enable all interrupts for the device, this is the only bit
+ * in the register
+ */
+#define XIIC_GINTR_ENABLE_MASK      0x80000000UL
+
+#define xiic_tx_space(i2c) ((i2c)->tx_msg->len - (i2c)->tx_pos)
+#define xiic_rx_space(i2c) ((i2c)->rx_msg->len - (i2c)->rx_pos)
+
+static void xiic_start_xfer(struct xiic_i2c *i2c);
+static void __xiic_start_xfer(struct xiic_i2c *i2c);
+
+static inline void xiic_setreg8(struct xiic_i2c *i2c, int reg, u8 value)
+{
+	iowrite8(value, i2c->base + reg);
+}
+
+static inline u8 xiic_getreg8(struct xiic_i2c *i2c, int reg)
+{
+	return ioread8(i2c->base + reg);
+}
+
+static inline void xiic_setreg16(struct xiic_i2c *i2c, int reg, u16 value)
+{
+	iowrite16(value, i2c->base + reg);
+}
+
+static inline void xiic_setreg32(struct xiic_i2c *i2c, int reg, int value)
+{
+	iowrite32(value, i2c->base + reg);
+}
+
+static inline int xiic_getreg32(struct xiic_i2c *i2c, int reg)
+{
+	return ioread32(i2c->base + reg);
+}
+
+static inline void xiic_irq_dis(struct xiic_i2c *i2c, u32 mask)
+{
+	u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
+	xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier & ~mask);
+}
+
+static inline void xiic_irq_en(struct xiic_i2c *i2c, u32 mask)
+{
+	u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
+	xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier | mask);
+}
+
+static inline void xiic_irq_clr(struct xiic_i2c *i2c, u32 mask)
+{
+	u32 isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
+	xiic_setreg32(i2c, XIIC_IISR_OFFSET, isr & mask);
+}
+
+static inline void xiic_irq_clr_en(struct xiic_i2c *i2c, u32 mask)
+{
+	xiic_irq_clr(i2c, mask);
+	xiic_irq_en(i2c, mask);
+}
+
+static void xiic_clear_rx_fifo(struct xiic_i2c *i2c)
+{
+	u8 sr;
+	for (sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
+		!(sr & XIIC_SR_RX_FIFO_EMPTY_MASK);
+		sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET))
+		xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
+}
+
+static void xiic_reinit(struct xiic_i2c *i2c)
+{
+	xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
+
+	/* Set receive Fifo depth to maximum (zero based). */
+	xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, IIC_RX_FIFO_DEPTH - 1);
+
+	/* Reset Tx Fifo. */
+	xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_TX_FIFO_RESET_MASK);
+
+	/* Enable IIC Device, remove Tx Fifo reset & disable general call. */
+	xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_ENABLE_DEVICE_MASK);
+
+	/* make sure RX fifo is empty */
+	xiic_clear_rx_fifo(i2c);
+
+	/* Enable interrupts */
+	xiic_setreg32(i2c, XIIC_DGIER_OFFSET, XIIC_GINTR_ENABLE_MASK);
+
+	xiic_irq_clr_en(i2c, XIIC_INTR_AAS_MASK | XIIC_INTR_ARB_LOST_MASK);
+}
+
+static void xiic_deinit(struct xiic_i2c *i2c)
+{
+	u8 cr;
+
+	xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
+
+	/* Disable IIC Device. */
+	cr = xiic_getreg8(i2c, XIIC_CR_REG_OFFSET);
+	xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, cr & ~XIIC_CR_ENABLE_DEVICE_MASK);
+}
+
+static void xiic_read_rx(struct xiic_i2c *i2c)
+{
+	u8 bytes_in_fifo;
+	int i;
+
+	bytes_in_fifo = xiic_getreg8(i2c, XIIC_RFO_REG_OFFSET) + 1;
+
+	dev_dbg(i2c->adap.dev.parent, "%s entry, bytes in fifo: %d, msg: %d"
+		", SR: 0x%x, CR: 0x%x\n",
+		__func__, bytes_in_fifo, xiic_rx_space(i2c),
+		xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
+		xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
+
+	if (bytes_in_fifo > xiic_rx_space(i2c))
+		bytes_in_fifo = xiic_rx_space(i2c);
+
+	for (i = 0; i < bytes_in_fifo; i++)
+		i2c->rx_msg->buf[i2c->rx_pos++] =
+			xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
+
+	xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET,
+		(xiic_rx_space(i2c) > IIC_RX_FIFO_DEPTH) ?
+		IIC_RX_FIFO_DEPTH - 1 :  xiic_rx_space(i2c) - 1);
+}
+
+static int xiic_tx_fifo_space(struct xiic_i2c *i2c)
+{
+	/* return the actual space left in the FIFO */
+	return IIC_TX_FIFO_DEPTH - xiic_getreg8(i2c, XIIC_TFO_REG_OFFSET) - 1;
+}
+
+static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
+{
+	u8 fifo_space = xiic_tx_fifo_space(i2c);
+	int len = xiic_tx_space(i2c);
+
+	len = (len > fifo_space) ? fifo_space : len;
+
+	dev_dbg(i2c->adap.dev.parent, "%s entry, len: %d, fifo space: %d\n",
+		__func__, len, fifo_space);
+
+	while (len--) {
+		u16 data = i2c->tx_msg->buf[i2c->tx_pos++];
+		if ((xiic_tx_space(i2c) == 0) && (i2c->nmsgs == 1)) {
+			/* last message in transfer -> STOP */
+			data |= XIIC_TX_DYN_STOP_MASK;
+			dev_dbg(i2c->adap.dev.parent, "%s TX STOP\n", __func__);
+
+			xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
+		} else
+			xiic_setreg8(i2c, XIIC_DTR_REG_OFFSET, data);
+	}
+}
+
+static void xiic_wakeup(struct xiic_i2c *i2c, int code)
+{
+	i2c->tx_msg = NULL;
+	i2c->rx_msg = NULL;
+	i2c->nmsgs = 0;
+	i2c->state = code;
+	wake_up(&i2c->wait);
+}
+
+static void xiic_process(struct xiic_i2c *i2c)
+{
+	u32 pend, isr, ier;
+	u32 clr = 0;
+
+	/* Get the interrupt Status from the IPIF. There is no clearing of
+	 * interrupts in the IPIF. Interrupts must be cleared at the source.
+	 * To find which interrupts are pending; AND interrupts pending with
+	 * interrupts masked.
+	 */
+	isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
+	ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
+	pend = isr & ier;
+
+	dev_dbg(i2c->adap.dev.parent, "%s entry, IER: 0x%x, ISR: 0x%x, "
+		"pend: 0x%x, SR: 0x%x, msg: %p, nmsgs: %d\n",
+		__func__, ier, isr, pend, xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
+		i2c->tx_msg, i2c->nmsgs);
+
+	/* Do not processes a devices interrupts if the device has no
+	 * interrupts pending
+	 */
+	if (!pend)
+		return;
+
+	/* Service requesting interrupt */
+	if ((pend & XIIC_INTR_ARB_LOST_MASK) ||
+		((pend & XIIC_INTR_TX_ERROR_MASK) &&
+		!(pend & XIIC_INTR_RX_FULL_MASK))) {
+		/* bus arbritration lost, or...
+		 * Transmit error _OR_ RX completed
+		 * if this happens when RX_FULL is not set
+		 * this is probably a TX error
+		 */
+
+		dev_dbg(i2c->adap.dev.parent, "%s error\n", __func__);
+
+		/* dynamic mode seem to suffer from problems if we just flushes
+		 * fifos and the next message is a TX with len 0 (only addr)
+		 * reset the IP instead of just flush fifos
+		 */
+		xiic_reinit(i2c);
+
+		if (i2c->tx_msg)
+			xiic_wakeup(i2c, STATE_ERROR);
+
+	} else if (pend & XIIC_INTR_RX_FULL_MASK) {
+		/* Receive register/FIFO is full */
+
+		clr = XIIC_INTR_RX_FULL_MASK;
+		if (!i2c->rx_msg) {
+			dev_dbg(i2c->adap.dev.parent,
+				"%s unexpexted RX IRQ\n", __func__);
+			xiic_clear_rx_fifo(i2c);
+			goto out;
+		}
+
+		xiic_read_rx(i2c);
+		if (xiic_rx_space(i2c) == 0) {
+			/* this is the last part of the message */
+			i2c->rx_msg = NULL;
+
+			/* also clear TX error if there (RX complete) */
+			clr |= (isr & XIIC_INTR_TX_ERROR_MASK);
+
+			dev_dbg(i2c->adap.dev.parent,
+				"%s end of message, nmsgs: %d\n",
+				__func__, i2c->nmsgs);
+
+			/* send next message if this wasn't the last,
+			 * otherwise the transfer will be finialise when
+			 * receiving the bus not busy interrupt
+			 */
+			if (i2c->nmsgs > 1) {
+				i2c->nmsgs--;
+				i2c->tx_msg++;
+				dev_dbg(i2c->adap.dev.parent,
+					"%s will start next...\n", __func__);
+
+				__xiic_start_xfer(i2c);
+			}
+		}
+	} else if (pend & XIIC_INTR_BNB_MASK) {
+		/* IIC bus has transitioned to not busy */
+		clr = XIIC_INTR_BNB_MASK;
+
+		/* The bus is not busy, disable BusNotBusy interrupt */
+		xiic_irq_dis(i2c, XIIC_INTR_BNB_MASK);
+
+		if (!i2c->tx_msg)
+			goto out;
+
+		if ((i2c->nmsgs == 1) && !i2c->rx_msg &&
+			xiic_tx_space(i2c) == 0)
+			xiic_wakeup(i2c, STATE_DONE);
+		else
+			xiic_wakeup(i2c, STATE_ERROR);
+
+	} else if (pend & (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)) {
+		/* Transmit register/FIFO is empty or ½ empty */
+
+		clr = pend &
+			(XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK);
+
+		if (!i2c->tx_msg) {
+			dev_dbg(i2c->adap.dev.parent,
+				"%s unexpexted TX IRQ\n", __func__);
+			goto out;
+		}
+
+		xiic_fill_tx_fifo(i2c);
+
+		/* current message sent and there is space in the fifo */
+		if (!xiic_tx_space(i2c) && xiic_tx_fifo_space(i2c) >= 2) {
+			dev_dbg(i2c->adap.dev.parent,
+				"%s end of message sent, nmsgs: %d\n",
+				__func__, i2c->nmsgs);
+			if (i2c->nmsgs > 1) {
+				i2c->nmsgs--;
+				i2c->tx_msg++;
+				__xiic_start_xfer(i2c);
+			} else {
+				xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
+
+				dev_err(i2c->adap.dev.parent,
+					"%s Got TX IRQ but no more to do...\n",
+					__func__);
+			}
+		} else if (!xiic_tx_space(i2c) && (i2c->nmsgs == 1))
+			/* current frame is sent and is last,
+			 * make sure to disable tx half
+			 */
+			xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
+	} else {
+		/* got IRQ which is not acked */
+		dev_err(i2c->adap.dev.parent, "%s Got unexpected IRQ\n",
+			__func__);
+		clr = pend;
+	}
+out:
+	dev_dbg(i2c->adap.dev.parent, "%s clr: 0x%x\n", __func__, clr);
+
+	xiic_setreg32(i2c, XIIC_IISR_OFFSET, clr);
+}
+
+static int xiic_bus_busy(struct xiic_i2c *i2c)
+{
+	u8 sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
+
+	return (sr & XIIC_SR_BUS_BUSY_MASK) ? -EBUSY : 0;
+}
+
+static int xiic_busy(struct xiic_i2c *i2c)
+{
+	int tries = 3;
+	int err;
+
+	if (i2c->tx_msg)
+		return -EBUSY;
+
+	/* for instance if previous transfer was terminated due to TX error
+	 * it might be that the bus is on it's way to become available
+	 * give it at most 3 ms to wake
+	 */
+	err = xiic_bus_busy(i2c);
+	while (err && tries--) {
+		mdelay(1);
+		err = xiic_bus_busy(i2c);
+	}
+
+	return err;
+}
+
+static void xiic_start_recv(struct xiic_i2c *i2c)
+{
+	u8 rx_watermark;
+	struct i2c_msg *msg = i2c->rx_msg = i2c->tx_msg;
+
+	/* Clear and enable Rx full interrupt. */
+	xiic_irq_clr_en(i2c, XIIC_INTR_RX_FULL_MASK | XIIC_INTR_TX_ERROR_MASK);
+
+	/* we want to get all but last byte, because the TX_ERROR IRQ is used
+	 * to inidicate error ACK on the address, and negative ack on the last
+	 * received byte, so to not mix them receive all but last.
+	 * In the case where there is only one byte to receive
+	 * we can check if ERROR and RX full is set at the same time
+	 */
+	rx_watermark = msg->len;
+	if (rx_watermark > IIC_RX_FIFO_DEPTH)
+		rx_watermark = IIC_RX_FIFO_DEPTH;
+	xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, rx_watermark - 1);
+
+	if (!(msg->flags & I2C_M_NOSTART))
+		/* write the address */
+		xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
+			(msg->addr << 1) | XIIC_READ_OPERATION |
+			XIIC_TX_DYN_START_MASK);
+
+	xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
+
+	xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
+		msg->len | ((i2c->nmsgs == 1) ? XIIC_TX_DYN_STOP_MASK : 0));
+	if (i2c->nmsgs == 1)
+		/* very last, enable bus not busy as well */
+		xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
+
+	/* the message is tx:ed */
+	i2c->tx_pos = msg->len;
+}
+
+static void xiic_start_send(struct xiic_i2c *i2c)
+{
+	struct i2c_msg *msg = i2c->tx_msg;
+
+	xiic_irq_clr(i2c, XIIC_INTR_TX_ERROR_MASK);
+
+	dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, len: %d, "
+		"ISR: 0x%x, CR: 0x%x\n",
+		__func__, msg, msg->len, xiic_getreg32(i2c, XIIC_IISR_OFFSET),
+		xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
+
+	if (!(msg->flags & I2C_M_NOSTART)) {
+		/* write the address */
+		u16 data = ((msg->addr << 1) & 0xfe) | XIIC_WRITE_OPERATION |
+			XIIC_TX_DYN_START_MASK;
+		if ((i2c->nmsgs == 1) && msg->len == 0)
+			/* no data and last message -> add STOP */
+			data |= XIIC_TX_DYN_STOP_MASK;
+
+		xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
+	}
+
+	xiic_fill_tx_fifo(i2c);
+
+	/* Clear any pending Tx empty, Tx Error and then enable them. */
+	xiic_irq_clr_en(i2c, XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_ERROR_MASK |
+		XIIC_INTR_BNB_MASK);
+}
+
+static irqreturn_t xiic_isr(int irq, void *dev_id)
+{
+	struct xiic_i2c *i2c = dev_id;
+
+	spin_lock(&i2c->lock);
+	/* disable interrupts globally */
+	xiic_setreg32(i2c, XIIC_DGIER_OFFSET, 0);
+
+	dev_dbg(i2c->adap.dev.parent, "%s entry\n", __func__);
+
+	xiic_process(i2c);
+
+	xiic_setreg32(i2c, XIIC_DGIER_OFFSET, XIIC_GINTR_ENABLE_MASK);
+	spin_unlock(&i2c->lock);
+
+	return IRQ_HANDLED;
+}
+
+static void __xiic_start_xfer(struct xiic_i2c *i2c)
+{
+	int first = 1;
+	int fifo_space = xiic_tx_fifo_space(i2c);
+	dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, fifos space: %d\n",
+		__func__, i2c->tx_msg, fifo_space);
+
+	if (!i2c->tx_msg)
+		return;
+
+	i2c->rx_pos = 0;
+	i2c->tx_pos = 0;
+	i2c->state = STATE_START;
+	while ((fifo_space >= 2) && (first || (i2c->nmsgs > 1))) {
+		if (!first) {
+			i2c->nmsgs--;
+			i2c->tx_msg++;
+			i2c->tx_pos = 0;
+		} else
+			first = 0;
+
+		if (i2c->tx_msg->flags & I2C_M_RD) {
+			/* we dont date putting several reads in the FIFO */
+			xiic_start_recv(i2c);
+			return;
+		} else {
+			xiic_start_send(i2c);
+			if (xiic_tx_space(i2c) != 0) {
+				/* the message could not be completely sent */
+				break;
+			}
+		}
+
+		fifo_space = xiic_tx_fifo_space(i2c);
+	}
+
+	/* there are more messages or the current one could not be completely
+	 * put into the FIFO, also enable the half empty interrupt
+	 */
+	if (i2c->nmsgs > 1 || xiic_tx_space(i2c))
+		xiic_irq_clr_en(i2c, XIIC_INTR_TX_HALF_MASK);
+
+}
+
+static void xiic_start_xfer(struct xiic_i2c *i2c)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+	xiic_reinit(i2c);
+	/* disable interrupts globally */
+	xiic_setreg32(i2c, XIIC_DGIER_OFFSET, 0);
+	spin_unlock_irqrestore(&i2c->lock, flags);
+
+	__xiic_start_xfer(i2c);
+	xiic_setreg32(i2c, XIIC_DGIER_OFFSET, XIIC_GINTR_ENABLE_MASK);
+}
+
+static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct xiic_i2c *i2c = i2c_get_adapdata(adap);
+	int err;
+
+	dev_dbg(adap->dev.parent, "%s entry SR: 0x%x\n", __func__,
+		xiic_getreg8(i2c, XIIC_SR_REG_OFFSET));
+
+	err = xiic_busy(i2c);
+	if (err)
+		return err;
+
+	i2c->tx_msg = msgs;
+	i2c->nmsgs = num;
+
+	xiic_start_xfer(i2c);
+
+	if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
+		(i2c->state == STATE_DONE), HZ))
+		return (i2c->state == STATE_DONE) ? num : -EIO;
+	else {
+		i2c->tx_msg = NULL;
+		i2c->rx_msg = NULL;
+		i2c->nmsgs = 0;
+		return -ETIMEDOUT;
+	}
+}
+
+static u32 xiic_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm xiic_algorithm = {
+	.master_xfer	= xiic_xfer,
+	.functionality	= xiic_func,
+};
+
+static struct i2c_adapter xiic_adapter = {
+	.owner		= THIS_MODULE,
+	.name		= DRIVER_NAME,
+	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
+	.algo		= &xiic_algorithm,
+};
+
+
+static int __devinit xiic_i2c_probe(struct platform_device *pdev)
+{
+	struct xiic_i2c *i2c;
+	struct xiic_i2c_platform_data *pdata;
+	struct resource *res;
+	int ret, irq;
+	u8 i;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto resource_missing;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		goto resource_missing;
+
+	pdata = (struct xiic_i2c_platform_data *) pdev->dev.platform_data;
+	if (!pdata)
+		return -EINVAL;
+
+	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
+		dev_err(&pdev->dev, "Memory region busy\n");
+		ret = -EBUSY;
+		goto request_mem_failed;
+	}
+
+	i2c->base = ioremap(res->start, resource_size(res));
+	if (!i2c->base) {
+		dev_err(&pdev->dev, "Unable to map registers\n");
+		ret = -EIO;
+		goto map_failed;
+	}
+
+	/* hook up driver to tree */
+	platform_set_drvdata(pdev, i2c);
+	i2c->adap = xiic_adapter;
+	i2c_set_adapdata(&i2c->adap, i2c);
+	i2c->adap.dev.parent = &pdev->dev;
+
+	xiic_reinit(i2c);
+
+	spin_lock_init(&i2c->lock);
+	init_waitqueue_head(&i2c->wait);
+	ret = request_irq(irq, xiic_isr, 0, pdev->name, i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot claim IRQ\n");
+		goto request_irq_failed;
+	}
+
+	/* add i2c adapter to i2c tree */
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add adapter\n");
+		goto add_adapter_failed;
+	}
+
+	/* add in known devices to the bus */
+	for (i = 0; i < pdata->num_devices; i++)
+		i2c_new_device(&i2c->adap, pdata->devices + i);
+
+	return 0;
+
+add_adapter_failed:
+	free_irq(irq, i2c);
+request_irq_failed:
+	xiic_deinit(i2c);
+	iounmap(i2c->base);
+map_failed:
+	release_mem_region(res->start, resource_size(res));
+request_mem_failed:
+	kfree(i2c);
+
+	return ret;
+resource_missing:
+	dev_err(&pdev->dev, "IRQ or Memory resource is missing\n");
+	return -ENOENT;
+}
+
+static int __devexit xiic_i2c_remove(struct platform_device* pdev)
+{
+	struct xiic_i2c *i2c = platform_get_drvdata(pdev);
+	struct resource *res;
+
+	/* remove adapter & data */
+	i2c_del_adapter(&i2c->adap);
+
+	xiic_deinit(i2c);
+
+	platform_set_drvdata(pdev, NULL);
+
+	free_irq(platform_get_irq(pdev, 0), i2c);
+
+	iounmap(i2c->base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res)
+		release_mem_region(res->start, resource_size(res));
+
+	kfree(i2c);
+
+	return 0;
+}
+
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:"DRIVER_NAME);
+
+static struct platform_driver xiic_i2c_driver = {
+	.probe   = xiic_i2c_probe,
+	.remove  = __devexit_p(xiic_i2c_remove),
+	.driver  = {
+		.owner = THIS_MODULE,
+		.name = DRIVER_NAME,
+	},
+};
+
+static int __init xiic_i2c_init(void)
+{
+	return platform_driver_register(&xiic_i2c_driver);
+}
+
+static void __exit xiic_i2c_exit(void)
+{
+	platform_driver_unregister(&xiic_i2c_driver);
+}
+
+module_init(xiic_i2c_init);
+module_exit(xiic_i2c_exit);
+
+MODULE_AUTHOR("info-l7gf1WXxx3uGw+nKnLezzg@public.gmane.org");
+MODULE_DESCRIPTION("Xilinx I2C bus driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/i2c-xiic.h b/include/linux/i2c-xiic.h
new file mode 100644
index 0000000..4f9f225
--- /dev/null
+++ b/include/linux/i2c-xiic.h
@@ -0,0 +1,43 @@
+/*
+ * i2c-xiic.h
+ * Copyright (c) 2009 Intel Corporation
+ *
+ * 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.
+ *
+ * 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.
+ */
+
+/* Supports:
+ * Xilinx IIC
+ */
+
+#ifndef _LINUX_I2C_XIIC_H
+#define _LINUX_I2C_XIIC_H
+
+/**
+ * struct xiic_i2c_platform_data - Platform data of the Xilinx I2C driver
+ * @num_devices:	Number of devices that shall be added when the driver
+ *			is probed.
+ * @devices:		The actuall devices to add.
+ *
+ * This purpose of this platform data struct is to be able to provide a number
+ * of devices that should be added to the I2C bus. The reason is that sometimes
+ * the I2C board info is not enough, a new PCI board can for instance be
+ * plugged into a standard PC, and the bus number might be unknown at
+ * early init time.
+ */
+struct xiic_i2c_platform_data {
+	u8				num_devices;
+	struct i2c_board_info const	*devices;
+};
+
+#endif /* _LINUX_I2C_XIIC_H */

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