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>

1 files changed, 709 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-nuc900.c b/drivers/i2c/busses/i2c-nuc900.c
new file mode 100644
index 000000000000..92d770d7bbc2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-nuc900.c
@@ -0,0 +1,709 @@
+/*
+ * 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");