[PATCH] OpenCores I2C bus driver

[Peter Korsgaard <jacmet@sunsite.dk>]

Hi,

The following patch adds support for the OpenCores I2C controller IP
core (See http://www.opencores.org/projects.cgi/web/i2c/overview).

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
---

 drivers/i2c/busses/Kconfig      |   11 +
 drivers/i2c/busses/Makefile     |    1 
 drivers/i2c/busses/i2c-ocores.c |  358 ++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c-ocores.h      |   20 ++
 4 files changed, 390 insertions(+)

Index: linux/drivers/i2c/busses/Kconfig
===================================================================
--- linux.orig/drivers/i2c/busses/Kconfig	2006-04-19 10:24:35.000000000 +0200
+++ linux/drivers/i2c/busses/Kconfig	2006-04-19 10:24:38.000000000 +0200
@@ -517,4 +517,15 @@
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-mv64xxx.
 
+config I2C_OCORES
+	tristate "OpenCores I2C Controller"
+	depends on I2C
+	help
+	  If you say yes to this option, support will be included for the
+	  OpenCores I2C controller. For details see
+	  http://www.opencores.org/projects.cgi/web/i2c/overview
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-ocores.
+
 endmenu
Index: linux/drivers/i2c/busses/Makefile
===================================================================
--- linux.orig/drivers/i2c/busses/Makefile	2006-03-20 06:53:29.000000000 +0100
+++ linux/drivers/i2c/busses/Makefile	2006-04-19 10:24:38.000000000 +0200
@@ -40,6 +40,7 @@
 obj-$(CONFIG_I2C_VIA)		+= i2c-via.o
 obj-$(CONFIG_I2C_VIAPRO)	+= i2c-viapro.o
 obj-$(CONFIG_I2C_VOODOO3)	+= i2c-voodoo3.o
+obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 obj-$(CONFIG_SCx200_I2C)	+= scx200_i2c.o
 
Index: linux/drivers/i2c/busses/i2c-ocores.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux/drivers/i2c/busses/i2c-ocores.c	2006-04-21 10:51:05.000000000 +0200
@@ -0,0 +1,358 @@
+/*
+ * i2c-ocores.c: I2C bus driver for OpenCores I2C controller
+ * (http://www.opencores.org/projects.cgi/web/i2c/overview).
+ *
+ * Peter Korsgaard <jacmet@sunsite.dk>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/wait.h>
+#include <linux/i2c-ocores.h>
+
+struct ocores_i2c {
+	void __iomem *base;
+	int regstep;
+	wait_queue_head_t wait;
+	struct i2c_adapter adap;
+	struct i2c_msg *msg;
+	int pos;
+	int nmsgs;
+	int state; /* see STATE_ */
+};
+
+/* registers */
+#define OCI2C_PRELOW 		0
+#define OCI2C_PREHIGH 		1
+#define OCI2C_CONTROL 		2
+#define OCI2C_DATA 		3
+#define OCI2C_CMD     		4
+#define OCI2C_STATUS  		4
+
+#define OCI2C_CMD_START		0x91
+#define OCI2C_CMD_STOP		0x41
+#define OCI2C_CMD_READ		0x21
+#define OCI2C_CMD_WRITE		0x11
+#define OCI2C_CMD_READ_ACK	0x21
+#define OCI2C_CMD_READ_NACK	0x29
+#define OCI2C_CMD_IACK		0x01
+
+#define OCI2C_STAT_BUSY		0x40
+#define OCI2C_STAT_TIP		0x02
+#define OCI2C_STAT_NACK		0x80
+#define OCI2C_STAT_ARBLOST	0x20
+#define OCI2C_STAT_IF		0x01
+
+#define STATE_DONE  0
+#define STATE_START 1
+#define STATE_WRITE 2
+#define STATE_READ  3
+#define STATE_ERROR 4
+
+static __inline__ void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
+{
+	iowrite8(value, i2c->base + reg * i2c->regstep);
+}
+
+static __inline__ u8 oc_getreg(struct ocores_i2c *i2c, int reg)
+{
+	return ioread8(i2c->base + reg * i2c->regstep);
+}
+
+static void ocores_process(struct ocores_i2c *i2c)
+{
+	struct i2c_msg *msg = i2c->msg;
+	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
+
+	if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR))
+	{
+		/* stop has been sent */
+		oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
+		wake_up_interruptible(&i2c->wait);
+		return;
+	}
+
+	/* error? */
+	if (stat & OCI2C_STAT_ARBLOST)
+	{
+		i2c->state = STATE_ERROR;
+		oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
+		return;
+	}
+
+	if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE))
+	{
+		i2c->state =
+			(msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
+
+		if (stat & OCI2C_STAT_NACK)
+		{
+			i2c->state = STATE_ERROR;
+			oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
+			return;
+		}
+	}
+	else
+		msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
+
+	/* end of msg? */
+	if (i2c->pos == msg->len)
+	{
+		i2c->nmsgs--;
+		i2c->msg++;
+		i2c->pos = 0;
+		msg = i2c->msg;
+
+		if (i2c->nmsgs) /* end? */
+		{
+			/* send start? */
+			if (!(msg->flags & I2C_M_NOSTART))
+			{
+				u8 addr = (msg->addr << 1);
+
+				if (msg->flags & I2C_M_RD)
+					addr |= 1;
+
+				i2c->state = STATE_START;
+
+				oc_setreg(i2c, OCI2C_DATA, addr);
+				oc_setreg(i2c, OCI2C_CMD,  OCI2C_CMD_START);
+				return;
+			}
+			else
+				i2c->state = (msg->flags & I2C_M_RD)
+					? STATE_READ : STATE_WRITE;
+		}
+		else
+		{
+			i2c->state = STATE_DONE;
+			oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
+			return;
+		}
+	}
+
+	if (i2c->state == STATE_READ)
+	{
+		oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
+			  OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
+	}
+	else
+	{
+		oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
+		oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
+	}
+}
+
+static irqreturn_t ocores_isr(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct ocores_i2c *i2c = dev_id;
+
+	ocores_process(i2c);
+
+	return IRQ_HANDLED;
+}
+
+static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct ocores_i2c *i2c = i2c_get_adapdata(adap);
+
+	i2c->msg   = msgs;
+	i2c->pos   = 0;
+	i2c->nmsgs = num;
+	i2c->state = STATE_START;
+
+	oc_setreg(i2c, OCI2C_DATA,
+			(i2c->msg->addr << 1) |
+			((i2c->msg->flags & I2C_M_RD) ? 1:0));
+
+	oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
+
+	if (wait_event_interruptible_timeout(i2c->wait,
+					     (i2c->state == STATE_ERROR) ||
+					     (i2c->state == STATE_DONE), HZ*5))
+		return (i2c->state == STATE_DONE) ? num : -EIO;
+	else
+		return -ETIMEDOUT;
+}
+
+static void ocores_init(struct ocores_i2c *i2c,
+			struct ocores_i2c_platform_data *pdata)
+{
+	int prescale;
+
+	/* make sure the device is disabled */
+	oc_setreg(i2c, OCI2C_CONTROL, 0);
+
+	prescale = (pdata->clock_khz / (5*100)) - 1;
+	oc_setreg(i2c, OCI2C_PRELOW,  prescale & 0xff);
+	oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
+
+	/* Init the device */
+	oc_setreg(i2c, OCI2C_CMD,     OCI2C_CMD_IACK);
+	oc_setreg(i2c, OCI2C_CONTROL, 0xc0);
+}
+
+
+static u32 ocores_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm ocores_algorithm = {
+	.master_xfer	= ocores_xfer,
+	.functionality	= ocores_func,
+};
+
+static struct i2c_adapter ocores_adapter = {
+	.owner		= THIS_MODULE,
+	.name		= "i2c-ocores",
+	.class		= I2C_CLASS_HWMON,
+	.algo		= &ocores_algorithm,
+	.timeout	= 2,
+	.retries	= 1
+};
+
+
+static int __devinit ocores_i2c_probe(struct platform_device *pdev)
+{
+	struct ocores_i2c* i2c;
+	struct ocores_i2c_platform_data* pdata;
+	struct resource *res, *res2;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!res2)
+		return -ENODEV;
+
+	pdata = (struct ocores_i2c_platform_data*) pdev->dev.platform_data;
+	if (!pdata)
+		return -ENODEV;
+
+	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	if (!request_mem_region(res->start, res->end - res->start + 1,
+				pdev->name)) {
+		dev_err(&pdev->dev, "Memory region busy\n");
+		ret = -EBUSY;
+		goto request_mem_failed;
+	}
+
+	i2c->base = ioremap(res->start, res->end - res->start + 1);
+	if (!i2c->base)
+	{
+		dev_err(&pdev->dev, "Unable to map registers\n");
+		ret = -EIO;
+		goto map_failed;
+	}
+
+	i2c->regstep = pdata->regstep;
+	ocores_init(i2c, pdata);
+
+	init_waitqueue_head(&i2c->wait);
+	ret = request_irq(res2->start, ocores_isr, 0,
+			  pdev->name, i2c);
+	if (ret)
+	{
+		dev_err(&pdev->dev, "Cannot claim IRQ\n");
+		goto request_irq_failed;
+	}
+
+	/* hook up driver to tree */
+	platform_set_drvdata(pdev, i2c);
+	i2c->adap = ocores_adapter;
+	i2c_set_adapdata(&i2c->adap, i2c);
+	i2c->adap.dev.parent = &pdev->dev;
+
+	/* 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;
+	}
+
+	return 0;
+
+ add_adapter_failed:
+	free_irq(res2->start, i2c);
+ request_irq_failed:
+	iounmap(i2c->base);
+ map_failed:
+	release_mem_region(res->start, res->end - res->start + 1);
+ request_mem_failed:
+	kfree(i2c);
+
+	return ret;
+}
+
+static int __devexit ocores_i2c_remove(struct platform_device* pdev)
+{
+	struct ocores_i2c *i2c = platform_get_drvdata(pdev);
+	struct resource *res;
+
+	/* disable i2c logic */
+	oc_setreg(i2c, OCI2C_CONTROL, 0);
+
+	/* remove adapter & data */
+	i2c_del_adapter(&i2c->adap);
+	platform_set_drvdata(pdev, NULL);
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (res)
+		free_irq(res->start, i2c);
+
+	iounmap(i2c->base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res)
+		release_mem_region(res->start, res->end - res->start + 1);
+
+	kfree(i2c);
+
+	return 0;
+}
+
+static struct platform_driver ocores_i2c_driver = {
+	.probe  = ocores_i2c_probe,
+	.remove = ocores_i2c_remove,
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = "ocores-i2c",
+	},
+};
+
+static int __init ocores_i2c_init(void)
+{
+	return platform_driver_register(&ocores_i2c_driver);
+}
+
+static void __exit ocores_i2c_exit(void)
+{
+	platform_driver_unregister(&ocores_i2c_driver);
+}
+
+module_init(ocores_i2c_init);
+module_exit(ocores_i2c_exit);
+
+MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
+MODULE_DESCRIPTION("OpenCores I2C bus driver");
+MODULE_LICENSE("GPL");
Index: linux/include/linux/i2c-ocores.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux/include/linux/i2c-ocores.h	2006-04-21 10:54:43.000000000 +0200
@@ -0,0 +1,20 @@
+/*
+ * i2c-ocores.h - definitions for the i2c-ocores interface
+ *
+ * Peter Korsgaard <jacmet@sunsite.dk>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#ifndef _LINUX_I2C_OCORES_H
+#define _LINUX_I2C_OCORES_H
+
+struct ocores_i2c_platform_data {
+	u32 regstep;   /* distance between registers */
+	u32 clock_khz; /* input clock in KHz */
+};
+
+#endif /* _LINUX_I2C_OCORES_H */
+

-- 
Bye, Peter Korsgaard