i2c/nuc900: add i2c driver support for nuc900

This patch is to add i2c driver support for nuc900.
Signed-off-by: Wan ZongShun <mcuos.com@gmail.org>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
Reviewed-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

arch/arm/mach-w90x900/include/mach/i2c.h

+#ifndef __ASM_ARCH_NUC900_I2C_H
+#define __ASM_ARCH_NUC900_I2C_H
+
+struct nuc900_platform_i2c {
+	int		bus_num;
+	unsigned long   bus_freq;
+};
+
+#endif /* __ASM_ARCH_NUC900_I2C_H */

drivers/i2c/busses/Kconfig

@@ -448,6 +448,13 @@ config I2C_NOMADIK
 	  If you say yes to this option, support will be included for the
 	  I2C interface from ST-Ericsson's Nomadik and Ux500 architectures.
 
+config I2C_NUC900
+	tristate "NUC900 I2C Driver"
+	depends on ARCH_W90X900
+	help
+	  Say Y here to include support for I2C controller in the
+	  Winbond/Nuvoton NUC900 based System-on-Chip devices.
+
 config I2C_OCORES
 	tristate "OpenCores I2C Controller"
 	depends on EXPERIMENTAL

drivers/i2c/busses/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_I2C_IXP2000)	+= i2c-ixp2000.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
 obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
 obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
+obj-$(CONFIG_I2C_NUC900)	+= i2c-nuc900.o
 obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
 obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
 obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o

drivers/i2c/busses/i2c-nuc900.c

+/*
+ * linux/drivers/i2c/busses/i2c-nuc900.c
+ *
+ * Copyright (c) 2010 Nuvoton technology corporation.
+ *
+ * This driver based on S3C2410 I2C driver of Ben Dooks <ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org>.
+ * Written by Wan ZongShun <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * 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;version 2 of the License.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/i2c.h>
+#include <linux/i2c-id.h>
+#include <linux/init.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+
+#include <mach/mfp.h>
+#include <mach/i2c.h>
+
+/* nuc900 i2c registers offset */
+
+#define CSR		0x00
+#define DIVIDER		0x04
+#define CMDR		0x08
+#define SWR		0x0C
+#define RXR		0x10
+#define TXR		0x14
+
+/* nuc900 i2c CSR register bits */
+
+#define IRQEN		0x003
+#define I2CBUSY		0x400
+#define I2CSTART	0x018
+#define IRQFLAG		0x004
+#define ARBIT_LOST	0x200
+#define SLAVE_ACK	0x800
+
+/* nuc900 i2c CMDR register bits */
+
+#define I2C_CMD_START	0x10
+#define I2C_CMD_STOP	0x08
+#define I2C_CMD_READ	0x04
+#define I2C_CMD_WRITE	0x02
+#define I2C_CMD_NACK	0x01
+
+/* i2c controller state */
+
+enum nuc900_i2c_state {
+	STATE_IDLE,
+	STATE_START,
+	STATE_READ,
+	STATE_WRITE,
+	STATE_STOP
+};
+
+/* i2c controller private data */
+
+struct nuc900_i2c {
+	spinlock_t		lock;
+	wait_queue_head_t	wait;
+
+	struct i2c_msg		*msg;
+	unsigned int		msg_num;
+	unsigned int		msg_idx;
+	unsigned int		msg_ptr;
+	unsigned int		irq;
+
+	enum nuc900_i2c_state	state;
+
+	void __iomem		*regs;
+	struct clk		*clk;
+	struct device		*dev;
+	struct resource		*ioarea;
+	struct i2c_adapter	adap;
+};
+
+/* nuc900_i2c_master_complete
+ *
+ * complete the message and wake up the caller, using the given return code,
+ * or zero to mean ok.
+*/
+
+static inline void nuc900_i2c_master_complete(struct nuc900_i2c *i2c, int ret)
+{
+	dev_dbg(i2c->dev, "master_complete %d\n", ret);
+
+	i2c->msg_ptr = 0;
+	i2c->msg = NULL;
+	i2c->msg_idx++;
+	i2c->msg_num = 0;
+	if (ret)
+		i2c->msg_idx = ret;
+
+	wake_up(&i2c->wait);
+}
+
+/* irq enable/disable functions */
+
+static inline void nuc900_i2c_disable_irq(struct nuc900_i2c *i2c)
+{
+	unsigned long tmp;
+
+	tmp = readl(i2c->regs + CSR);
+	writel(tmp & ~IRQEN, i2c->regs + CSR);
+}
+
+static inline void nuc900_i2c_enable_irq(struct nuc900_i2c *i2c)
+{
+	unsigned long tmp;
+
+	tmp = readl(i2c->regs + CSR);
+	writel(tmp | IRQEN, i2c->regs + CSR);
+}
+
+
+/* nuc900_i2c_message_start
+ *
+ * put the start of a message onto the bus
+*/
+
+static void nuc900_i2c_message_start(struct nuc900_i2c *i2c,
+				      struct i2c_msg *msg)
+{
+	unsigned int addr = (msg->addr & 0x7f) << 1;
+
+	if (msg->flags & I2C_M_RD)
+		addr |= 0x1;
+	writel(addr & 0xff, i2c->regs + TXR);
+	writel(I2C_CMD_START | I2C_CMD_WRITE, i2c->regs + CMDR);
+}
+
+static inline void nuc900_i2c_stop(struct nuc900_i2c *i2c, int ret)
+{
+
+	dev_dbg(i2c->dev, "STOP\n");
+
+	/* stop the transfer */
+	i2c->state = STATE_STOP;
+	writel(I2C_CMD_STOP, i2c->regs + CMDR);
+
+	nuc900_i2c_master_complete(i2c, ret);
+	nuc900_i2c_disable_irq(i2c);
+}
+
+/* helper functions to determine the current state in the set of
+ * messages we are sending
+*/
+
+/* is_lastmsg()
+ *
+ * returns TRUE if the current message is the last in the set
+*/
+
+static inline int is_lastmsg(struct nuc900_i2c *i2c)
+{
+	return i2c->msg_idx >= (i2c->msg_num - 1);
+}
+
+/* is_msglast
+ *
+ * returns TRUE if we this is the last byte in the current message
+*/
+
+static inline int is_msglast(struct nuc900_i2c *i2c)
+{
+	return i2c->msg_ptr == i2c->msg->len-1;
+}
+
+/* is_msgend
+ *
+ * returns TRUE if we reached the end of the current message
+*/
+
+static inline int is_msgend(struct nuc900_i2c *i2c)
+{
+	return i2c->msg_ptr >= i2c->msg->len;
+}
+
+/* i2c_nuc900_irq_nextbyte
+ *
+ * process an interrupt and work out what to do
+ */
+
+static void i2c_nuc900_irq_nextbyte(struct nuc900_i2c *i2c,
+							unsigned long iicstat)
+{
+	unsigned char byte;
+
+	switch (i2c->state) {
+
+	case STATE_IDLE:
+		dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
+		break;
+
+	case STATE_STOP:
+		dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
+		nuc900_i2c_disable_irq(i2c);
+		break;
+
+	case STATE_START:
+		/* last thing we did was send a start condition on the
+		 * bus, or started a new i2c message
+		 */
+
+		if (iicstat & SLAVE_ACK &&
+		    !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
+			/* ack was not received... */
+
+			dev_dbg(i2c->dev, "ack was not received\n");
+			nuc900_i2c_stop(i2c, -ENXIO);
+			break;
+		}
+
+		if (i2c->msg->flags & I2C_M_RD)
+			i2c->state = STATE_READ;
+		else
+			i2c->state = STATE_WRITE;
+
+		/* terminate the transfer if there is nothing to do
+		 * as this is used by the i2c probe to find devices.
+		*/
+
+		if (is_lastmsg(i2c) && i2c->msg->len == 0) {
+			nuc900_i2c_stop(i2c, 0);
+			break;
+		}
+
+		if (i2c->state == STATE_READ)
+			goto prepare_read;
+
+		/* fall through to the write state, as we will need to
+		 * send a byte as well
+		*/
+
+	case STATE_WRITE:
+		/* we are writing data to the device... check for the
+		 * end of the message, and if so, work out what to do
+		 */
+
+		if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
+			if (iicstat & SLAVE_ACK) {
+				dev_dbg(i2c->dev, "WRITE: No Ack\n");
+
+				nuc900_i2c_stop(i2c, -ECONNREFUSED);
+				break;
+			}
+		}
+
+retry_write:
+
+		if (!is_msgend(i2c)) {
+			byte = i2c->msg->buf[i2c->msg_ptr++];
+			writeb(byte, i2c->regs + TXR);
+			writel(I2C_CMD_WRITE, i2c->regs + CMDR);
+
+		} else if (!is_lastmsg(i2c)) {
+			/* we need to go to the next i2c message */
+
+			dev_dbg(i2c->dev, "WRITE: Next Message\n");
+
+			i2c->msg_ptr = 0;
+			i2c->msg_idx++;
+			i2c->msg++;
+
+			/* check to see if we need to do another message */
+			if (i2c->msg->flags & I2C_M_NOSTART) {
+
+				if (i2c->msg->flags & I2C_M_RD) {
+					/* cannot do this, the controller
+					 * forces us to send a new START
+					 * when we change direction
+					*/
+
+					nuc900_i2c_stop(i2c, -EINVAL);
+				}
+
+				goto retry_write;
+			} else {
+				/* send the new start */
+				nuc900_i2c_message_start(i2c, i2c->msg);
+				i2c->state = STATE_START;
+			}
+
+		} else {
+			/* send stop */
+
+			nuc900_i2c_stop(i2c, 0);
+		}
+		break;
+
+	case STATE_READ:
+		/* we have a byte of data in the data register, do
+		 * something with it, and then work out wether we are
+		 * going to do any more read/write
+		 */
+
+		byte = readb(i2c->regs + RXR);
+		i2c->msg->buf[i2c->msg_ptr++] = byte;
+
+prepare_read:
+		if (is_msglast(i2c)) {
+			/* last byte of buffer */
+
+			if (is_lastmsg(i2c))
+				writel(I2C_CMD_READ | I2C_CMD_NACK,
+							i2c->regs + CMDR);
+
+		} else if (is_msgend(i2c)) {
+			/* ok, we've read the entire buffer, see if there
+			 * is anything else we need to do
+			*/
+
+			if (is_lastmsg(i2c)) {
+				/* last message, send stop and complete */
+				dev_dbg(i2c->dev, "READ: Send Stop\n");
+
+				nuc900_i2c_stop(i2c, 0);
+			} else {
+				/* go to the next transfer */
+				dev_dbg(i2c->dev, "READ: Next Transfer\n");
+
+				i2c->msg_ptr = 0;
+				i2c->msg_idx++;
+				i2c->msg++;
+
+				writel(I2C_CMD_READ, i2c->regs + CMDR);
+			}
+
+		} else {
+			writel(I2C_CMD_READ, i2c->regs + CMDR);
+		}
+
+		break;
+	}
+}
+
+/* nuc900_i2c_irq
+ *
+ * top level IRQ servicing routine
+*/
+
+static irqreturn_t nuc900_i2c_irq(int irqno, void *dev_id)
+{
+	struct nuc900_i2c *i2c = dev_id;
+	unsigned long status;
+
+	status = readl(i2c->regs + CSR);
+	writel(status | IRQFLAG, i2c->regs + CSR);
+
+	if (status & ARBIT_LOST) {
+		/* deal with arbitration loss */
+		dev_err(i2c->dev, "deal with arbitration loss\n");
+		goto out;
+	}
+
+	if (i2c->state == STATE_IDLE) {
+		dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
+		goto out;
+	}
+
+	/* pretty much this leaves us with the fact that we've
+	 * transmitted or received whatever byte we last sent
+	*/
+
+	i2c_nuc900_irq_nextbyte(i2c, status);
+
+ out:
+	return IRQ_HANDLED;
+}
+
+
+/* nuc900_i2c_set_master
+ *
+ * get the i2c bus for a master transaction
+*/
+
+static int nuc900_i2c_set_master(struct nuc900_i2c *i2c)
+{
+	int timeout = 400;
+
+	while (timeout-- > 0) {
+		if (((readl(i2c->regs + SWR) & I2CSTART) == I2CSTART) &&
+				((readl(i2c->regs + CSR) & I2CBUSY) == 0)) {
+			return 0;
+		}
+
+		msleep(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+/* nuc900_i2c_doxfer
+ *
+ * this starts an i2c transfer
+*/
+
+static int nuc900_i2c_doxfer(struct nuc900_i2c *i2c,
+			      struct i2c_msg *msgs, int num)
+{
+	unsigned long iicstat, timeout;
+	int spins = 20;
+	int ret;
+
+	ret = nuc900_i2c_set_master(i2c);
+	if (ret != 0) {
+		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	spin_lock_irq(&i2c->lock);
+
+	i2c->msg     = msgs;
+	i2c->msg_num = num;
+	i2c->msg_ptr = 0;
+	i2c->msg_idx = 0;
+	i2c->state   = STATE_START;
+
+	nuc900_i2c_message_start(i2c, msgs);
+	spin_unlock_irq(&i2c->lock);
+
+	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
+
+	ret = i2c->msg_idx;
+
+	/* having these next two as dev_err() makes life very
+	 * noisy when doing an i2cdetect
+	*/
+
+	if (timeout == 0)
+		dev_dbg(i2c->dev, "timeout\n");
+	else if (ret != num)
+		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
+
+	/* ensure the stop has been through the bus */
+
+	dev_dbg(i2c->dev, "waiting for bus idle\n");
+
+	/* first, try busy waiting briefly */
+	do {
+		iicstat = readl(i2c->regs + CSR);
+	} while ((iicstat & I2CBUSY) && --spins);
+
+	/* if that timed out sleep */
+	if (!spins) {
+		msleep(1);
+		iicstat = readl(i2c->regs + CSR);
+	}
+
+	if (iicstat & I2CBUSY)
+		dev_warn(i2c->dev, "timeout waiting for bus idle\n");
+
+ out:
+	return ret;
+}
+
+/* nuc900_i2c_xfer
+ *
+ * first port of call from the i2c bus code when an message needs
+ * transferring across the i2c bus.
+*/
+
+static int nuc900_i2c_xfer(struct i2c_adapter *adap,
+			struct i2c_msg *msgs, int num)
+{
+	struct nuc900_i2c *i2c = (struct nuc900_i2c *)adap->algo_data;
+	int retry;
+	int ret;
+
+	nuc900_i2c_enable_irq(i2c);
+
+	for (retry = 0; retry < adap->retries; retry++) {
+
+		ret = nuc900_i2c_doxfer(i2c, msgs, num);
+
+		if (ret != -EAGAIN)
+			return ret;
+
+		dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
+
+		udelay(100);
+	}
+
+	return -EREMOTEIO;
+}
+
+/* declare our i2c functionality */
+static u32 nuc900_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
+}
+
+/* i2c bus registration info */
+
+static const struct i2c_algorithm nuc900_i2c_algorithm = {
+	.master_xfer		= nuc900_i2c_xfer,
+	.functionality		= nuc900_i2c_func,
+};
+
+/* nuc900_i2c_probe
+ *
+ * called by the bus driver when a suitable device is found
+*/
+
+static int __devinit nuc900_i2c_probe(struct platform_device *pdev)
+{
+	struct nuc900_i2c *i2c;
+	struct nuc900_platform_i2c *pdata;
+	struct resource *res;
+	int ret;
+
+	pdata = pdev->dev.platform_data;
+	if (!pdata) {
+		dev_err(&pdev->dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
+	if (!i2c) {
+		dev_err(&pdev->dev, "no memory for state\n");
+		return -ENOMEM;
+	}
+
+	strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
+	i2c->adap.owner   = THIS_MODULE;
+	i2c->adap.algo    = &nuc900_i2c_algorithm;
+	i2c->adap.retries = 2;
+	i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+
+	spin_lock_init(&i2c->lock);
+	init_waitqueue_head(&i2c->wait);
+
+	/* find the clock and enable it */
+
+	i2c->dev = &pdev->dev;
+	i2c->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&pdev->dev, "cannot get clock\n");
+		ret = -ENOENT;
+		goto err_noclk;
+	}
+
+	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
+
+	clk_enable(i2c->clk);
+
+	/* map the registers */
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "cannot find IO resource\n");
+		ret = -ENOENT;
+		goto err_clk;
+	}
+
+	i2c->ioarea = request_mem_region(res->start, resource_size(res),
+					 pdev->name);
+
+	if (i2c->ioarea == NULL) {
+		dev_err(&pdev->dev, "cannot request IO\n");
+		ret = -ENXIO;
+		goto err_clk;
+	}
+
+	i2c->regs = ioremap(res->start, resource_size(res));
+
+	if (i2c->regs == NULL) {
+		dev_err(&pdev->dev, "cannot map IO\n");
+		ret = -ENXIO;
+		goto err_ioarea;
+	}
+
+	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
+		i2c->regs, i2c->ioarea, res);
+
+	/* setup info block for the i2c core */
+
+	i2c->adap.algo_data = i2c;
+	i2c->adap.dev.parent = &pdev->dev;
+
+	mfp_set_groupg(&pdev->dev);
+
+	clk_get_rate(i2c->clk);
+
+	ret = (i2c->clk.apbfreq)/(pdata->bus_freq * 5) - 1;
+	writel(ret & 0xffff, i2c->regs + DIVIDER);
+
+	/* find the IRQ for this unit (note, this relies on the init call to
+	 * ensure no current IRQs pending
+	 */
+
+	i2c->irq = ret = platform_get_irq(pdev, 0);
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "cannot find IRQ\n");
+		goto err_iomap;
+	}
+
+	ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_DISABLED | IRQF_SHARED,
+			  dev_name(&pdev->dev), i2c);
+
+	if (ret != 0) {
+		dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
+		goto err_iomap;
+	}
+
+	/* Note, previous versions of the driver used i2c_add_adapter()
+	 * to add the bus at any number. We now pass the bus number via
+	 * the platform data, so if unset it will now default to always
+	 * being bus 0.
+	 */
+
+	i2c->adap.nr = pdata->bus_num;
+
+	ret = i2c_add_numbered_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
+		goto err_irq;
+	}
+
+	platform_set_drvdata(pdev, i2c);
+
+	dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
+						dev_name(&i2c->adap.dev));
+	return 0;
+
+ err_irq:
+	free_irq(i2c->irq, i2c);
+
+ err_iomap:
+	iounmap(i2c->regs);
+
+ err_ioarea:
+	release_resource(i2c->ioarea);
+	kfree(i2c->ioarea);
+
+ err_clk:
+	clk_disable(i2c->clk);
+	clk_put(i2c->clk);
+
+ err_noclk:
+	kfree(i2c);
+	return ret;
+}
+
+/* nuc900_i2c_remove
+ *
+ * called when device is removed from the bus
+*/
+
+static int __devexit nuc900_i2c_remove(struct platform_device *pdev)
+{
+	struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	free_irq(i2c->irq, i2c);
+
+	clk_disable(i2c->clk);
+	clk_put(i2c->clk);
+
+	iounmap(i2c->regs);
+
+	release_resource(i2c->ioarea);
+	kfree(i2c->ioarea);
+	kfree(i2c);
+
+	return 0;
+}
+
+static struct platform_driver nuc900_i2c_driver = {
+	.probe		= nuc900_i2c_probe,
+	.remove		= __devexit_p(nuc900_i2c_remove),
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "nuc900-i2c0",
+	},
+};
+
+static int __init i2c_adap_nuc900_init(void)
+{
+	return platform_driver_register(&nuc900_i2c_driver);
+}
+
+static void __exit i2c_adap_nuc900_exit(void)
+{
+	platform_driver_unregister(&nuc900_i2c_driver);
+}
+subsys_initcall(i2c_adap_nuc900_init);
+module_exit(i2c_adap_nuc900_exit);
+
+MODULE_DESCRIPTION("NUC900 I2C Bus driver");
+MODULE_AUTHOR("Wan ZongShun, <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:nuc900-i2c0");