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linux/drivers/i2c/busses/i2c-ocores.c
Ganesan Ramalingam 7326e38ffe i2c: i2c-ocores: support for 16bit and 32bit IO 
Some architectures supports only 16-bit or 32-bit read/write access to
their IO space. Add a 'reg-io-width' platform and OF parameter which
specifies the IO width to support these platforms.

reg-io-width can be specified as 1, 2 or 4, and has a default value
of 1 if it is unspecified.

Signed-off-by: Ganesan Ramalingam <ganesanr@broadcom.com>
Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
2012-07-14 13:30:25 +02:00

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/*
* 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.
*/
/*
* This driver can be used from the device tree, see
* Documentation/devicetree/bindings/i2c/ocore-i2c.txt
*/
#include <linux/kernel.h>
#include <linux/module.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 <linux/slab.h>
#include <linux/io.h>
#include <linux/of_i2c.h>
#include <linux/log2.h>
struct ocores_i2c {
void __iomem *base;
u32 reg_shift;
u32 reg_io_width;
wait_queue_head_t wait;
struct i2c_adapter adap;
struct i2c_msg *msg;
int pos;
int nmsgs;
int state; /* see STATE_ */
int clock_khz;
};
/* registers */
#define OCI2C_PRELOW 0
#define OCI2C_PREHIGH 1
#define OCI2C_CONTROL 2
#define OCI2C_DATA 3
#define OCI2C_CMD 4 /* write only */
#define OCI2C_STATUS 4 /* read only, same address as OCI2C_CMD */
#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)
{
if (i2c->reg_io_width == 4)
iowrite32(value, i2c->base + (reg << i2c->reg_shift));
else if (i2c->reg_io_width == 2)
iowrite16(value, i2c->base + (reg << i2c->reg_shift));
else
iowrite8(value, i2c->base + (reg << i2c->reg_shift));
}
static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
{
if (i2c->reg_io_width == 4)
return ioread32(i2c->base + (reg << i2c->reg_shift));
else if (i2c->reg_io_width == 2)
return ioread16(i2c->base + (reg << i2c->reg_shift));
else
return ioread8(i2c->base + (reg << i2c->reg_shift));
}
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 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)
{
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 = (i2c->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 const 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 | I2C_CLASS_SPD,
.algo = &ocores_algorithm,
};
#ifdef CONFIG_OF
static int ocores_i2c_of_probe(struct platform_device *pdev,
struct ocores_i2c *i2c)
{
struct device_node *np = pdev->dev.of_node;
u32 val;
if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) {
/* no 'reg-shift', check for deprecated 'regstep' */
if (!of_property_read_u32(np, "regstep", &val)) {
if (!is_power_of_2(val)) {
dev_err(&pdev->dev, "invalid regstep %d\n",
val);
return -EINVAL;
}
i2c->reg_shift = ilog2(val);
dev_warn(&pdev->dev,
"regstep property deprecated, use reg-shift\n");
}
}
if (of_property_read_u32(np, "clock-frequency", &val)) {
dev_err(&pdev->dev,
"Missing required parameter 'clock-frequency'\n");
return -ENODEV;
}
i2c->clock_khz = val / 1000;
of_property_read_u32(pdev->dev.of_node, "reg-io-width",
&i2c->reg_io_width);
return 0;
}
#else
#define ocores_i2c_of_probe(pdev,i2c) -ENODEV
#endif
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;
int i;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!res2)
return -ENODEV;
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
if (!devm_request_mem_region(&pdev->dev, res->start,
resource_size(res), pdev->name)) {
dev_err(&pdev->dev, "Memory region busy\n");
return -EBUSY;
}
i2c->base = devm_ioremap_nocache(&pdev->dev, res->start,
resource_size(res));
if (!i2c->base) {
dev_err(&pdev->dev, "Unable to map registers\n");
return -EIO;
}
pdata = pdev->dev.platform_data;
if (pdata) {
i2c->reg_shift = pdata->reg_shift;
i2c->reg_io_width = pdata->reg_io_width;
i2c->clock_khz = pdata->clock_khz;
} else {
ret = ocores_i2c_of_probe(pdev, i2c);
if (ret)
return ret;
}
if (i2c->reg_io_width == 0)
i2c->reg_io_width = 1; /* Set to default value */
ocores_init(i2c);
init_waitqueue_head(&i2c->wait);
ret = devm_request_irq(&pdev->dev, res2->start, ocores_isr, 0,
pdev->name, i2c);
if (ret) {
dev_err(&pdev->dev, "Cannot claim IRQ\n");
return ret;
}
/* 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;
i2c->adap.dev.of_node = pdev->dev.of_node;
/* add i2c adapter to i2c tree */
ret = i2c_add_adapter(&i2c->adap);
if (ret) {
dev_err(&pdev->dev, "Failed to add adapter\n");
return ret;
}
/* add in known devices to the bus */
if (pdata) {
for (i = 0; i < pdata->num_devices; i++)
i2c_new_device(&i2c->adap, pdata->devices + i);
} else {
of_i2c_register_devices(&i2c->adap);
}
return 0;
}
static int __devexit ocores_i2c_remove(struct platform_device *pdev)
{
struct ocores_i2c *i2c = platform_get_drvdata(pdev);
/* 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);
return 0;
}
#ifdef CONFIG_PM
static int ocores_i2c_suspend(struct device *dev)
{
struct ocores_i2c *i2c = dev_get_drvdata(dev);
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));
return 0;
}
static int ocores_i2c_resume(struct device *dev)
{
struct ocores_i2c *i2c = dev_get_drvdata(dev);
ocores_init(i2c);
return 0;
}
static SIMPLE_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume);
#define OCORES_I2C_PM (&ocores_i2c_pm)
#else
#define OCORES_I2C_PM NULL
#endif
static struct of_device_id ocores_i2c_match[] = {
{ .compatible = "opencores,i2c-ocores", },
{},
};
MODULE_DEVICE_TABLE(of, ocores_i2c_match);
static struct platform_driver ocores_i2c_driver = {
.probe = ocores_i2c_probe,
.remove = __devexit_p(ocores_i2c_remove),
.driver = {
.owner = THIS_MODULE,
.name = "ocores-i2c",
.of_match_table = ocores_i2c_match,
.pm = OCORES_I2C_PM,
},
};
module_platform_driver(ocores_i2c_driver);
MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
MODULE_DESCRIPTION("OpenCores I2C bus driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ocores-i2c");
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