On 04/20/2010 09:19 PM, Scott McNutt wrote:
+void __led_init(led_id_t mask, int state) +{
- gpio_direction_output(mask, (state == STATUS_LED_ON) ? 0 : 1);
The direction register only exists when the PIO core hardware is configured in bidirectional mode.
If the PIO core hardware is configured in output-only mode, reading from data returns an undefined value.
As I recall, the older designs configured the LED PIO ports as output only ... which is why board/altera/common/epled.c was coded in such a manner.
Hi Scott,
This is not for Altera PIO interface. I followed the gpio interface of Linux, linux-2.6/Documentation/gpio.txt, and created a trivial bit addressing gpio core, which uses fewer LE and doesn't required interrupt disabled to write a bit. With this core, all output pins are bidirectional and can be read. I used it to access i2c, one-wire, leds, buttons and nand flash busy flag in nios2 linux. I didn't add irq support, because input layer of linux can do debounce. Please look at http://nioswiki.com/GPIO.
Best regards, Thomas