[Wrong e-mail address first time, sorry for that]
On Tuesday 15 December 2009 09:47:22 Albert Burbea wrote:
> Hi everybody,
Hi,
> I would like to know how can I use an I2C device inside a device driver.
> The problem is that I wish to leave the I2C available to other application
> on the platform, and I do not wish to do add_driver every time I need
> access to the I2C from the driver. Actually I need a handle that is always
> open in the driver.
I use something like this for my touchscreen driver:
static int davinci_tsc2004_read(u8 size, u8 * val, u16 addr)
{
struct i2c_adapter *adap;
int err;
struct i2c_msg msg[1];
adap = i2c_get_adapter(1);
if (!adap)
return -ENODEV;
msg->addr = addr;
msg->flags = I2C_M_RD;
msg->len = size;
msg->buf = val;
err = i2c_transfer(adap, msg, 1);
if (err >= 0)
return 0;
return err;
}
Write operation is smilar, just using 0 instead of I2C_M_RD.
> Also, can I use the I2C driver in an isr handling code?
I don't think so, though I don't known new threaded interrupt handlers.
You should schedule a workqueue in your isr handler and use i2c calls in
workqueue. Again from my touchscreendriver:
static void tsc_workqueue_handler(struct work_struct *work)
{
/* Actual I2C stuff */
}
DECLARE_WORK(tsc_wq, tsc_workqueue_handler);
static irqreturn_t tsc2004_ts_irq_handler(int irq, void *dev_id)
{
/*
* Schedule the workqueue for I2C transfers
*/
schedule_work(&tsc_wq);
return IRQ_HANDLED;
}
Best regards,
Caglar
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