--- /dev/null
+/*
+ * 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");
projects / linux-beck.git / commitdiff