376 lines
8.5 KiB
C
376 lines
8.5 KiB
C
/*
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* i2c-ocores.c: I2C bus driver for OpenCores I2C controller
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* (http://www.opencores.org/projects.cgi/web/i2c/overview).
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*
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* Peter Korsgaard <jacmet@sunsite.dk>
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*
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* This file is licensed under the terms of the GNU General Public License
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* version 2. This program is licensed "as is" without any warranty of any
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* kind, whether express or implied.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/platform_device.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/wait.h>
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#include <linux/i2c-ocores.h>
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#include <asm/io.h>
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struct ocores_i2c {
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void __iomem *base;
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int regstep;
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wait_queue_head_t wait;
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struct i2c_adapter adap;
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struct i2c_msg *msg;
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int pos;
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int nmsgs;
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int state; /* see STATE_ */
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int clock_khz;
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};
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/* registers */
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#define OCI2C_PRELOW 0
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#define OCI2C_PREHIGH 1
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#define OCI2C_CONTROL 2
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#define OCI2C_DATA 3
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#define OCI2C_CMD 4 /* write only */
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#define OCI2C_STATUS 4 /* read only, same address as OCI2C_CMD */
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#define OCI2C_CTRL_IEN 0x40
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#define OCI2C_CTRL_EN 0x80
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#define OCI2C_CMD_START 0x91
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#define OCI2C_CMD_STOP 0x41
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#define OCI2C_CMD_READ 0x21
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#define OCI2C_CMD_WRITE 0x11
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#define OCI2C_CMD_READ_ACK 0x21
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#define OCI2C_CMD_READ_NACK 0x29
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#define OCI2C_CMD_IACK 0x01
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#define OCI2C_STAT_IF 0x01
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#define OCI2C_STAT_TIP 0x02
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#define OCI2C_STAT_ARBLOST 0x20
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#define OCI2C_STAT_BUSY 0x40
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#define OCI2C_STAT_NACK 0x80
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#define STATE_DONE 0
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#define STATE_START 1
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#define STATE_WRITE 2
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#define STATE_READ 3
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#define STATE_ERROR 4
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static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
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{
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iowrite8(value, i2c->base + reg * i2c->regstep);
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}
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static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
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{
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return ioread8(i2c->base + reg * i2c->regstep);
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}
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static void ocores_process(struct ocores_i2c *i2c)
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{
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struct i2c_msg *msg = i2c->msg;
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u8 stat = oc_getreg(i2c, OCI2C_STATUS);
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if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
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/* stop has been sent */
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
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wake_up(&i2c->wait);
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return;
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}
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/* error? */
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if (stat & OCI2C_STAT_ARBLOST) {
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i2c->state = STATE_ERROR;
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
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return;
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}
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if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
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i2c->state =
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(msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
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if (stat & OCI2C_STAT_NACK) {
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i2c->state = STATE_ERROR;
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
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return;
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}
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} else
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msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
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/* end of msg? */
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if (i2c->pos == msg->len) {
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i2c->nmsgs--;
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i2c->msg++;
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i2c->pos = 0;
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msg = i2c->msg;
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if (i2c->nmsgs) { /* end? */
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/* send start? */
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if (!(msg->flags & I2C_M_NOSTART)) {
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u8 addr = (msg->addr << 1);
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if (msg->flags & I2C_M_RD)
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addr |= 1;
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i2c->state = STATE_START;
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oc_setreg(i2c, OCI2C_DATA, addr);
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
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return;
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} else
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i2c->state = (msg->flags & I2C_M_RD)
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? STATE_READ : STATE_WRITE;
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} else {
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i2c->state = STATE_DONE;
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
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return;
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}
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}
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if (i2c->state == STATE_READ) {
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oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
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OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
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} else {
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oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
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}
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}
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static irqreturn_t ocores_isr(int irq, void *dev_id)
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{
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struct ocores_i2c *i2c = dev_id;
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ocores_process(i2c);
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return IRQ_HANDLED;
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}
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static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
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{
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struct ocores_i2c *i2c = i2c_get_adapdata(adap);
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i2c->msg = msgs;
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i2c->pos = 0;
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i2c->nmsgs = num;
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i2c->state = STATE_START;
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oc_setreg(i2c, OCI2C_DATA,
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(i2c->msg->addr << 1) |
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((i2c->msg->flags & I2C_M_RD) ? 1:0));
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
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if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
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(i2c->state == STATE_DONE), HZ))
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return (i2c->state == STATE_DONE) ? num : -EIO;
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else
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return -ETIMEDOUT;
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}
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static void ocores_init(struct ocores_i2c *i2c)
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{
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int prescale;
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u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
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/* make sure the device is disabled */
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oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
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prescale = (i2c->clock_khz / (5*100)) - 1;
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oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
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oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
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/* Init the device */
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oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
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oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
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}
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static u32 ocores_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm ocores_algorithm = {
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.master_xfer = ocores_xfer,
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.functionality = ocores_func,
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};
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static struct i2c_adapter ocores_adapter = {
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.owner = THIS_MODULE,
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.name = "i2c-ocores",
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.class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
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.algo = &ocores_algorithm,
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};
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static int __devinit ocores_i2c_probe(struct platform_device *pdev)
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{
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struct ocores_i2c *i2c;
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struct ocores_i2c_platform_data *pdata;
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struct resource *res, *res2;
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int ret;
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int i;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!res)
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return -ENODEV;
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res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
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if (!res2)
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return -ENODEV;
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pdata = (struct ocores_i2c_platform_data*) pdev->dev.platform_data;
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if (!pdata)
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return -ENODEV;
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i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
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if (!i2c)
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return -ENOMEM;
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if (!request_mem_region(res->start, resource_size(res),
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pdev->name)) {
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dev_err(&pdev->dev, "Memory region busy\n");
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ret = -EBUSY;
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goto request_mem_failed;
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}
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i2c->base = ioremap(res->start, resource_size(res));
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if (!i2c->base) {
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dev_err(&pdev->dev, "Unable to map registers\n");
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ret = -EIO;
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goto map_failed;
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}
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i2c->regstep = pdata->regstep;
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i2c->clock_khz = pdata->clock_khz;
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ocores_init(i2c);
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init_waitqueue_head(&i2c->wait);
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ret = request_irq(res2->start, ocores_isr, 0, pdev->name, i2c);
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if (ret) {
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dev_err(&pdev->dev, "Cannot claim IRQ\n");
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goto request_irq_failed;
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}
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/* hook up driver to tree */
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platform_set_drvdata(pdev, i2c);
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i2c->adap = ocores_adapter;
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i2c_set_adapdata(&i2c->adap, i2c);
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i2c->adap.dev.parent = &pdev->dev;
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/* add i2c adapter to i2c tree */
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ret = i2c_add_adapter(&i2c->adap);
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if (ret) {
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dev_err(&pdev->dev, "Failed to add adapter\n");
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goto add_adapter_failed;
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}
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/* add in known devices to the bus */
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for (i = 0; i < pdata->num_devices; i++)
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i2c_new_device(&i2c->adap, pdata->devices + i);
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return 0;
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add_adapter_failed:
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free_irq(res2->start, i2c);
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request_irq_failed:
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iounmap(i2c->base);
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map_failed:
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release_mem_region(res->start, resource_size(res));
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request_mem_failed:
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kfree(i2c);
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return ret;
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}
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static int __devexit ocores_i2c_remove(struct platform_device* pdev)
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{
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struct ocores_i2c *i2c = platform_get_drvdata(pdev);
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struct resource *res;
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/* disable i2c logic */
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oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
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& ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
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/* remove adapter & data */
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i2c_del_adapter(&i2c->adap);
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platform_set_drvdata(pdev, NULL);
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res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
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if (res)
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free_irq(res->start, i2c);
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iounmap(i2c->base);
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (res)
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release_mem_region(res->start, resource_size(res));
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kfree(i2c);
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return 0;
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}
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#ifdef CONFIG_PM
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static int ocores_i2c_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct ocores_i2c *i2c = platform_get_drvdata(pdev);
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u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
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/* make sure the device is disabled */
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oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
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return 0;
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}
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static int ocores_i2c_resume(struct platform_device *pdev)
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{
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struct ocores_i2c *i2c = platform_get_drvdata(pdev);
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ocores_init(i2c);
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return 0;
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}
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#else
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#define ocores_i2c_suspend NULL
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#define ocores_i2c_resume NULL
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#endif
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/* work with hotplug and coldplug */
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MODULE_ALIAS("platform:ocores-i2c");
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static struct platform_driver ocores_i2c_driver = {
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.probe = ocores_i2c_probe,
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.remove = __devexit_p(ocores_i2c_remove),
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.suspend = ocores_i2c_suspend,
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.resume = ocores_i2c_resume,
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.driver = {
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.owner = THIS_MODULE,
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.name = "ocores-i2c",
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},
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};
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static int __init ocores_i2c_init(void)
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{
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return platform_driver_register(&ocores_i2c_driver);
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}
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static void __exit ocores_i2c_exit(void)
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{
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platform_driver_unregister(&ocores_i2c_driver);
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}
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module_init(ocores_i2c_init);
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module_exit(ocores_i2c_exit);
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MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
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MODULE_DESCRIPTION("OpenCores I2C bus driver");
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MODULE_LICENSE("GPL");
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