[PATCH] i2c: New bus driver for the OpenCores I2C controller

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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 355 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index d25a8cbbec0a..f7af7e9bb7d9 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -276,6 +276,17 @@ config I2C_NFORCE2
           This driver can also be built as a module.  If so, the module
           will be called i2c-nforce2.
 
+config I2C_OCORES
+        tristate "OpenCores I2C Controller"
+        depends on I2C && EXPERIMENTAL
+        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.
+
 config I2C_PARPORT
         tristate "Parallel port adapter"
         depends on I2C && PARPORT
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index b44831dff683..ac56df53155b 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 obj-$(CONFIG_I2C_MPC)           += i2c-mpc.o
 obj-$(CONFIG_I2C_MV64XXX)       += i2c-mv64xxx.o
 obj-$(CONFIG_I2C_NFORCE2)       += i2c-nforce2.o
+obj-$(CONFIG_I2C_OCORES)        += i2c-ocores.o
 obj-$(CONFIG_I2C_PARPORT)       += i2c-parport.o
 obj-$(CONFIG_I2C_PARPORT_LIGHT) += i2c-parport-light.o
 obj-$(CONFIG_I2C_PCA_ISA)       += i2c-pca-isa.o
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
new file mode 100644
index 000000000000..d5c0610bfe6d
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -0,0 +1,343 @@
+/*
+ * 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 <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/wait.h>
+#include <linux/i2c-ocores.h>
+#include <asm/io.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_CTRL_IEN          0x40
+#define OCI2C_CTRL_EN           0x80
+
+#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_IF           0x01
+#define OCI2C_STAT_TIP          0x02
+#define OCI2C_STAT_ARBLOST      0x20
+#define OCI2C_STAT_BUSY         0x40
+#define OCI2C_STAT_NACK         0x80
+
+#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(&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_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
+                               (i2c->state == STATE_DONE), HZ))
+                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;
+        u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
+
+        /* make sure the device is disabled */
+        oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
+
+        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, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
+}
+
+
+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, oc_getreg(i2c, OCI2C_CONTROL)
+                  & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
+
+        /* 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 = __devexit_p(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");