On Thu, 31 Jul 2008 19:43:54 +0900
Paul Mundt <[EMAIL PROTECTED]> wrote:
> This adds support for the SMBus adapter found in the various FPGAs on
> the Renesas Highlander platforms. Particularly the R0P7780LC0011RL and
> R0P7785LC0011RL FPGAs.
>
> Functionality is fairly restricted, in that only byte and block data
> transfers are supported. Normal/fast mode and IRQ/polling are also
> supported. Primarily used for various RTCs and thermal sensors.
>
> This version incorporates all of the comments from Jean Delvare and
> Trent Piepho.
>
> ...
>
> +static int highlander_i2c_read(struct highlander_i2c_dev *dev)
> +{
> + int i, cnt;
> + u16 data[16];
> +
> + if (highlander_i2c_wait_for_bbsy(dev))
> + return -EAGAIN;
> +
> + highlander_i2c_start(dev);
> +
> + if (highlander_i2c_wait_xfer_done(dev)) {
> + dev_err(dev->dev, "Arbitration loss\n");
> + return -EAGAIN;
> + }
> +
> + /*
> + * The R0P7780LC0011RL FPGA needs a significant delay between
> + * data read cycles, otherwise the transciever gets confused and
> + * garbage is returned when the read is subsequently aborted.
> + *
> + * It is not sufficient to wait for BBSY.
> + *
> + * While this generally only applies to the older SH7780-based
> + * Highlanders, the same issue can be observed on SH7785 ones,
> + * albeit less frequently. SH7780-based Highlanders may need
> + * this to be as high as 1000 ms.
> + */
> + if (iic_read_delay && time_before(jiffies, dev->last_read_time +
> + msecs_to_jiffies(iic_read_delay)))
> + msleep_interruptible(jiffies_to_msecs((dev->last_read_time +
> + msecs_to_jiffies(iic_read_delay)) - jiffies));
If this task has signal_pending(), msleep_interruptible() will
immediately return.
> + cnt = (dev->buf_len + 1) >> 1;
> + for (i = 0; i < cnt; i++) {
> + data[i] = ioread16(dev->base + SMTRDR + (i * sizeof(u16)));
> + dev_dbg(dev->dev, "read data[%x] 0x%04x\n", i, data[i]);
> + }
> +
> + smbus_read_data(data, dev->buf, dev->buf_len);
> +
> + dev->last_read_time = jiffies;
In which case I assume that the above will screw up.
> + return 0;
> +}
>
> ...
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