i2c: driver for the Synopsys DesignWare I2C controller

The i2c Linux driver for the DesignWare i2c block of Synopsys, which is meant
for AMBA Peripheral Bus. This i2c block is used on SoC chips like the ARM9
based PVG610.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 624 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c
new file mode 100644
index 00000000000..b444762e9b9
--- /dev/null
+++ b/drivers/i2c/busses/i2c-designware.c
@@ -0,0 +1,624 @@
+/*
+ * Synopsys Designware I2C adapter driver (master only).
+ *
+ * Based on the TI DAVINCI I2C adapter driver.
+ *
+ * Copyright (C) 2006 Texas Instruments.
+ * Copyright (C) 2007 MontaVista Software Inc.
+ * Copyright (C) 2009 Provigent Ltd.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * 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.
+ * ----------------------------------------------------------------------------
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/clk.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+
+/*
+ * Registers offset
+ */
+#define DW_IC_CON		0x0
+#define DW_IC_TAR		0x4
+#define DW_IC_DATA_CMD		0x10
+#define DW_IC_SS_SCL_HCNT	0x14
+#define DW_IC_SS_SCL_LCNT	0x18
+#define DW_IC_FS_SCL_HCNT	0x1c
+#define DW_IC_FS_SCL_LCNT	0x20
+#define DW_IC_INTR_STAT		0x2c
+#define DW_IC_INTR_MASK		0x30
+#define DW_IC_CLR_INTR		0x40
+#define DW_IC_ENABLE		0x6c
+#define DW_IC_STATUS		0x70
+#define DW_IC_TXFLR		0x74
+#define DW_IC_RXFLR		0x78
+#define DW_IC_COMP_PARAM_1	0xf4
+#define DW_IC_TX_ABRT_SOURCE	0x80
+
+#define DW_IC_CON_MASTER		0x1
+#define DW_IC_CON_SPEED_STD		0x2
+#define DW_IC_CON_SPEED_FAST		0x4
+#define DW_IC_CON_10BITADDR_MASTER	0x10
+#define DW_IC_CON_RESTART_EN		0x20
+#define DW_IC_CON_SLAVE_DISABLE		0x40
+
+#define DW_IC_INTR_TX_EMPTY	0x10
+#define DW_IC_INTR_TX_ABRT	0x40
+#define DW_IC_INTR_STOP_DET	0x200
+
+#define DW_IC_STATUS_ACTIVITY	0x1
+
+#define DW_IC_ERR_TX_ABRT	0x1
+
+/*
+ * status codes
+ */
+#define STATUS_IDLE			0x0
+#define STATUS_WRITE_IN_PROGRESS	0x1
+#define STATUS_READ_IN_PROGRESS		0x2
+
+#define TIMEOUT			20 /* ms */
+
+/*
+ * hardware abort codes from the DW_IC_TX_ABRT_SOURCE register
+ *
+ * only expected abort codes are listed here
+ * refer to the datasheet for the full list
+ */
+#define ABRT_7B_ADDR_NOACK	0
+#define ABRT_10ADDR1_NOACK	1
+#define ABRT_10ADDR2_NOACK	2
+#define ABRT_TXDATA_NOACK	3
+#define ABRT_GCALL_NOACK	4
+#define ABRT_GCALL_READ		5
+#define ABRT_SBYTE_ACKDET	7
+#define ABRT_SBYTE_NORSTRT	9
+#define ABRT_10B_RD_NORSTRT	10
+#define ARB_MASTER_DIS		11
+#define ARB_LOST		12
+
+static char *abort_sources[] = {
+	[ABRT_7B_ADDR_NOACK]	=
+		"slave address not acknowledged (7bit mode)",
+	[ABRT_10ADDR1_NOACK]	=
+		"first address byte not acknowledged (10bit mode)",
+	[ABRT_10ADDR2_NOACK]	=
+		"second address byte not acknowledged (10bit mode)",
+	[ABRT_TXDATA_NOACK]		=
+		"data not acknowledged",
+	[ABRT_GCALL_NOACK]		=
+		"no acknowledgement for a general call",
+	[ABRT_GCALL_READ]		=
+		"read after general call",
+	[ABRT_SBYTE_ACKDET]		=
+		"start byte acknowledged",
+	[ABRT_SBYTE_NORSTRT]	=
+		"trying to send start byte when restart is disabled",
+	[ABRT_10B_RD_NORSTRT]	=
+		"trying to read when restart is disabled (10bit mode)",
+	[ARB_MASTER_DIS]		=
+		"trying to use disabled adapter",
+	[ARB_LOST]			=
+		"lost arbitration",
+};
+
+/**
+ * struct dw_i2c_dev - private i2c-designware data
+ * @dev: driver model device node
+ * @base: IO registers pointer
+ * @cmd_complete: tx completion indicator
+ * @pump_msg: continue in progress transfers
+ * @lock: protect this struct and IO registers
+ * @clk: input reference clock
+ * @cmd_err: run time hadware error code
+ * @msgs: points to an array of messages currently being transfered
+ * @msgs_num: the number of elements in msgs
+ * @msg_write_idx: the element index of the current tx message in the msgs
+ *	array
+ * @tx_buf_len: the length of the current tx buffer
+ * @tx_buf: the current tx buffer
+ * @msg_read_idx: the element index of the current rx message in the msgs
+ *	array
+ * @rx_buf_len: the length of the current rx buffer
+ * @rx_buf: the current rx buffer
+ * @msg_err: error status of the current transfer
+ * @status: i2c master status, one of STATUS_*
+ * @abort_source: copy of the TX_ABRT_SOURCE register
+ * @irq: interrupt number for the i2c master
+ * @adapter: i2c subsystem adapter node
+ * @tx_fifo_depth: depth of the hardware tx fifo
+ * @rx_fifo_depth: depth of the hardware rx fifo
+ */
+struct dw_i2c_dev {
+	struct device		*dev;
+	void __iomem		*base;
+	struct completion	cmd_complete;
+	struct tasklet_struct	pump_msg;
+	struct mutex		lock;
+	struct clk		*clk;
+	int			cmd_err;
+	struct i2c_msg		*msgs;
+	int			msgs_num;
+	int			msg_write_idx;
+	u16			tx_buf_len;
+	u8			*tx_buf;
+	int			msg_read_idx;
+	u16			rx_buf_len;
+	u8			*rx_buf;
+	int			msg_err;
+	unsigned int		status;
+	u16			abort_source;
+	int			irq;
+	struct i2c_adapter	adapter;
+	unsigned int		tx_fifo_depth;
+	unsigned int		rx_fifo_depth;
+};
+
+/**
+ * i2c_dw_init() - initialize the designware i2c master hardware
+ * @dev: device private data
+ *
+ * This functions configures and enables the I2C master.
+ * This function is called during I2C init function, and in case of timeout at
+ * run time.
+ */
+static void i2c_dw_init(struct dw_i2c_dev *dev)
+{
+	u32 input_clock_khz = clk_get_rate(dev->clk) / 1000;
+	u16 ic_con;
+
+	/* Disable the adapter */
+	writeb(0, dev->base + DW_IC_ENABLE);
+
+	/* set standard and fast speed deviders for high/low periods */
+	writew((input_clock_khz * 40 / 10000)+1, /* std speed high, 4us */
+			dev->base + DW_IC_SS_SCL_HCNT);
+	writew((input_clock_khz * 47 / 10000)+1, /* std speed low, 4.7us */
+			dev->base + DW_IC_SS_SCL_LCNT);
+	writew((input_clock_khz *  6 / 10000)+1, /* fast speed high, 0.6us */
+			dev->base + DW_IC_FS_SCL_HCNT);
+	writew((input_clock_khz * 13 / 10000)+1, /* fast speed low, 1.3us */
+			dev->base + DW_IC_FS_SCL_LCNT);
+
+	/* configure the i2c master */
+	ic_con = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
+		DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
+	writew(ic_con, dev->base + DW_IC_CON);
+}
+
+/*
+ * Waiting for bus not busy
+ */
+static int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
+{
+	int timeout = TIMEOUT;
+
+	while (readb(dev->base + DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
+		if (timeout <= 0) {
+			dev_warn(dev->dev, "timeout waiting for bus ready\n");
+			return -ETIMEDOUT;
+		}
+		timeout--;
+		mdelay(1);
+	}
+
+	return 0;
+}
+
+/*
+ * Initiate low level master read/write transaction.
+ * This function is called from i2c_dw_xfer when starting a transfer.
+ * This function is also called from dw_i2c_pump_msg to continue a transfer
+ * that is longer than the size of the TX FIFO.
+ */
+static void
+i2c_dw_xfer_msg(struct i2c_adapter *adap)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+	struct i2c_msg *msgs = dev->msgs;
+	int num = dev->msgs_num;
+	u16 ic_con, intr_mask;
+	int tx_limit = dev->tx_fifo_depth - readb(dev->base + DW_IC_TXFLR);
+	int rx_limit = dev->rx_fifo_depth - readb(dev->base + DW_IC_RXFLR);
+	u16 addr = msgs[dev->msg_write_idx].addr;
+	u16 buf_len = dev->tx_buf_len;
+
+	if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) {
+		/* Disable the adapter */
+		writeb(0, dev->base + DW_IC_ENABLE);
+
+		/* set the slave (target) address */
+		writew(msgs[dev->msg_write_idx].addr, dev->base + DW_IC_TAR);
+
+		/* if the slave address is ten bit address, enable 10BITADDR */
+		ic_con = readw(dev->base + DW_IC_CON);
+		if (msgs[dev->msg_write_idx].flags & I2C_M_TEN)
+			ic_con |= DW_IC_CON_10BITADDR_MASTER;
+		else
+			ic_con &= ~DW_IC_CON_10BITADDR_MASTER;
+		writew(ic_con, dev->base + DW_IC_CON);
+
+		/* Enable the adapter */
+		writeb(1, dev->base + DW_IC_ENABLE);
+	}
+
+	for (; dev->msg_write_idx < num; dev->msg_write_idx++) {
+		/* if target address has changed, we need to
+		 * reprogram the target address in the i2c
+		 * adapter when we are done with this transfer
+		 */
+		if (msgs[dev->msg_write_idx].addr != addr)
+			return;
+
+		if (msgs[dev->msg_write_idx].len == 0) {
+			dev_err(dev->dev,
+				"%s: invalid message length\n", __func__);
+			dev->msg_err = -EINVAL;
+			return;
+		}
+
+		if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) {
+			/* new i2c_msg */
+			dev->tx_buf = msgs[dev->msg_write_idx].buf;
+			buf_len = msgs[dev->msg_write_idx].len;
+		}
+
+		while (buf_len > 0 && tx_limit > 0 && rx_limit > 0) {
+			if (msgs[dev->msg_write_idx].flags & I2C_M_RD) {
+				writew(0x100, dev->base + DW_IC_DATA_CMD);
+				rx_limit--;
+			} else
+				writew(*(dev->tx_buf++),
+						dev->base + DW_IC_DATA_CMD);
+			tx_limit--; buf_len--;
+		}
+	}
+
+	intr_mask = DW_IC_INTR_STOP_DET | DW_IC_INTR_TX_ABRT;
+	if (buf_len > 0) { /* more bytes to be written */
+		intr_mask |= DW_IC_INTR_TX_EMPTY;
+		dev->status |= STATUS_WRITE_IN_PROGRESS;
+	} else
+		dev->status &= ~STATUS_WRITE_IN_PROGRESS;
+	writew(intr_mask, dev->base + DW_IC_INTR_MASK);
+
+	dev->tx_buf_len = buf_len;
+}
+
+static void
+i2c_dw_read(struct i2c_adapter *adap)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+	struct i2c_msg *msgs = dev->msgs;
+	int num = dev->msgs_num;
+	u16 addr = msgs[dev->msg_read_idx].addr;
+	int rx_valid = readw(dev->base + DW_IC_RXFLR);
+
+	for (; dev->msg_read_idx < num; dev->msg_read_idx++) {
+		u16 len;
+		u8 *buf;
+
+		if (!(msgs[dev->msg_read_idx].flags & I2C_M_RD))
+			continue;
+
+		/* different i2c client, reprogram the i2c adapter */
+		if (msgs[dev->msg_read_idx].addr != addr)
+			return;
+
+		if (!(dev->status & STATUS_READ_IN_PROGRESS)) {
+			len = msgs[dev->msg_read_idx].len;
+			buf = msgs[dev->msg_read_idx].buf;
+		} else {
+			len = dev->rx_buf_len;
+			buf = dev->rx_buf;
+		}
+
+		for (; len > 0 && rx_valid > 0; len--, rx_valid--)
+			*buf++ = readb(dev->base + DW_IC_DATA_CMD);
+
+		if (len > 0) {
+			dev->status |= STATUS_READ_IN_PROGRESS;
+			dev->rx_buf_len = len;
+			dev->rx_buf = buf;
+			return;
+		} else
+			dev->status &= ~STATUS_READ_IN_PROGRESS;
+	}
+}
+
+/*
+ * Prepare controller for a transaction and call i2c_dw_xfer_msg
+ */
+static int
+i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+	int ret;
+
+	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
+
+	mutex_lock(&dev->lock);
+
+	INIT_COMPLETION(dev->cmd_complete);
+	dev->msgs = msgs;
+	dev->msgs_num = num;
+	dev->cmd_err = 0;
+	dev->msg_write_idx = 0;
+	dev->msg_read_idx = 0;
+	dev->msg_err = 0;
+	dev->status = STATUS_IDLE;
+
+	ret = i2c_dw_wait_bus_not_busy(dev);
+	if (ret < 0)
+		goto done;
+
+	/* start the transfers */
+	i2c_dw_xfer_msg(adap);
+
+	/* wait for tx to complete */
+	ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, HZ);
+	if (ret == 0) {
+		dev_err(dev->dev, "controller timed out\n");
+		i2c_dw_init(dev);
+		ret = -ETIMEDOUT;
+		goto done;
+	} else if (ret < 0)
+		goto done;
+
+	if (dev->msg_err) {
+		ret = dev->msg_err;
+		goto done;
+	}
+
+	/* no error */
+	if (likely(!dev->cmd_err)) {
+		/* read rx fifo, and disable the adapter */
+		do {
+			i2c_dw_read(adap);
+		} while (dev->status & STATUS_READ_IN_PROGRESS);
+		writeb(0, dev->base + DW_IC_ENABLE);
+		ret = num;
+		goto done;
+	}
+
+	/* We have an error */
+	if (dev->cmd_err == DW_IC_ERR_TX_ABRT) {
+		unsigned long abort_source = dev->abort_source;
+		int i;
+
+		for_each_bit(i, &abort_source, ARRAY_SIZE(abort_sources)) {
+		    dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);
+		}
+	}
+	ret = -EIO;
+
+done:
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static u32 i2c_dw_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR;
+}
+
+static void dw_i2c_pump_msg(unsigned long data)
+{
+	struct dw_i2c_dev *dev = (struct dw_i2c_dev *) data;
+	u16 intr_mask;
+
+	i2c_dw_read(&dev->adapter);
+	i2c_dw_xfer_msg(&dev->adapter);
+
+	intr_mask = DW_IC_INTR_STOP_DET | DW_IC_INTR_TX_ABRT;
+	if (dev->status & STATUS_WRITE_IN_PROGRESS)
+		intr_mask |= DW_IC_INTR_TX_EMPTY;
+	writew(intr_mask, dev->base + DW_IC_INTR_MASK);
+}
+
+/*
+ * Interrupt service routine. This gets called whenever an I2C interrupt
+ * occurs.
+ */
+static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
+{
+	struct dw_i2c_dev *dev = dev_id;
+	u16 stat;
+
+	stat = readw(dev->base + DW_IC_INTR_STAT);
+	dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
+	if (stat & DW_IC_INTR_TX_ABRT) {
+		dev->abort_source = readw(dev->base + DW_IC_TX_ABRT_SOURCE);
+		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
+		dev->status = STATUS_IDLE;
+	} else if (stat & DW_IC_INTR_TX_EMPTY)
+		tasklet_schedule(&dev->pump_msg);
+
+	readb(dev->base + DW_IC_CLR_INTR);	/* clear interrupts */
+	writew(0, dev->base + DW_IC_INTR_MASK);	/* disable interrupts */
+	if (stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET))
+		complete(&dev->cmd_complete);
+
+	return IRQ_HANDLED;
+}
+
+static struct i2c_algorithm i2c_dw_algo = {
+	.master_xfer	= i2c_dw_xfer,
+	.functionality	= i2c_dw_func,
+};
+
+static int __devinit dw_i2c_probe(struct platform_device *pdev)
+{
+	struct dw_i2c_dev *dev;
+	struct i2c_adapter *adap;
+	struct resource *mem, *irq, *ioarea;
+	int r;
+
+	/* NOTE: driver uses the static register mapping */
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem) {
+		dev_err(&pdev->dev, "no mem resource?\n");
+		return -EINVAL;
+	}
+
+	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!irq) {
+		dev_err(&pdev->dev, "no irq resource?\n");
+		return -EINVAL;
+	}
+
+	ioarea = request_mem_region(mem->start, resource_size(mem),
+			pdev->name);
+	if (!ioarea) {
+		dev_err(&pdev->dev, "I2C region already claimed\n");
+		return -EBUSY;
+	}
+
+	dev = kzalloc(sizeof(struct dw_i2c_dev), GFP_KERNEL);
+	if (!dev) {
+		r = -ENOMEM;
+		goto err_release_region;
+	}
+
+	init_completion(&dev->cmd_complete);
+	tasklet_init(&dev->pump_msg, dw_i2c_pump_msg, (unsigned long) dev);
+	mutex_init(&dev->lock);
+	dev->dev = get_device(&pdev->dev);
+	dev->irq = irq->start;
+	platform_set_drvdata(pdev, dev);
+
+	dev->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		r = -ENODEV;
+		goto err_free_mem;
+	}
+	clk_enable(dev->clk);
+
+	dev->base = ioremap(mem->start, resource_size(mem));
+	if (dev->base == NULL) {
+		dev_err(&pdev->dev, "failure mapping io resources\n");
+		r = -EBUSY;
+		goto err_unuse_clocks;
+	}
+	{
+		u32 param1 = readl(dev->base + DW_IC_COMP_PARAM_1);
+
+		dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
+		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
+	}
+	i2c_dw_init(dev);
+
+	writew(0, dev->base + DW_IC_INTR_MASK); /* disable IRQ */
+	r = request_irq(dev->irq, i2c_dw_isr, 0, pdev->name, dev);
+	if (r) {
+		dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
+		goto err_iounmap;
+	}
+
+	adap = &dev->adapter;
+	i2c_set_adapdata(adap, dev);
+	adap->owner = THIS_MODULE;
+	adap->class = I2C_CLASS_HWMON;
+	strlcpy(adap->name, "Synopsys DesignWare I2C adapter",
+			sizeof(adap->name));
+	adap->algo = &i2c_dw_algo;
+	adap->dev.parent = &pdev->dev;
+
+	adap->nr = pdev->id;
+	r = i2c_add_numbered_adapter(adap);
+	if (r) {
+		dev_err(&pdev->dev, "failure adding adapter\n");
+		goto err_free_irq;
+	}
+
+	return 0;
+
+err_free_irq:
+	free_irq(dev->irq, dev);
+err_iounmap:
+	iounmap(dev->base);
+err_unuse_clocks:
+	clk_disable(dev->clk);
+	clk_put(dev->clk);
+	dev->clk = NULL;
+err_free_mem:
+	platform_set_drvdata(pdev, NULL);
+	put_device(&pdev->dev);
+	kfree(dev);
+err_release_region:
+	release_mem_region(mem->start, resource_size(mem));
+
+	return r;
+}
+
+static int __devexit dw_i2c_remove(struct platform_device *pdev)
+{
+	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+	struct resource *mem;
+
+	platform_set_drvdata(pdev, NULL);
+	i2c_del_adapter(&dev->adapter);
+	put_device(&pdev->dev);
+
+	clk_disable(dev->clk);
+	clk_put(dev->clk);
+	dev->clk = NULL;
+
+	writeb(0, dev->base + DW_IC_ENABLE);
+	free_irq(dev->irq, dev);
+	kfree(dev);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(mem->start, resource_size(mem));
+	return 0;
+}
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:i2c_designware");
+
+static struct platform_driver dw_i2c_driver = {
+	.remove		= __devexit_p(dw_i2c_remove),
+	.driver		= {
+		.name	= "i2c_designware",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init dw_i2c_init_driver(void)
+{
+	return platform_driver_probe(&dw_i2c_driver, dw_i2c_probe);
+}
+module_init(dw_i2c_init_driver);
+
+static void __exit dw_i2c_exit_driver(void)
+{
+	platform_driver_unregister(&dw_i2c_driver);
+}
+module_exit(dw_i2c_exit_driver);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Synopsys DesignWare I2C bus adapter");
+MODULE_LICENSE("GPL");