[Avila] GPIO 14 data output

[Tim Harvey]

Ahmet,

GPIO14 is configured as a PCI clock in the redboot bootloader from the original Intel code for the IXP4XX boards.  You need to write your own kernel mode driver for linux that disables the PCI clock functionality and strobes it.  Note that it needs to be strobed quite frequently as the DS1918 times out after 1.12secs so you'll probably want to strobe it every 500ms or so.

enable:
   // NB: GPIO Clock Register GPCLKR is described in 12.4.7 pg 399 of the
   //     ixp42x developers manual
   GPCLKR_last = *IXP4XX_GPIO_GPCLKR;
   *IXP4XX_GPIO_GPCLKR &= ~0x1ff;// clear CKL0TC/CLK0DC bits to disable CLK0
   gpio_line_config(14, IXP4XX_GPIO_OUT);
   gpio_line_set(14, IXP4XX_GPIO_LOW);

strobe:
   gpio_line_set(14, IXP4XX_GPIO_HIGH);
   gpio_line_set(14, IXP4XX_GPIO_LOW);

Note that on the GW2347's there is a GPIO line used as a buffer enable to GPIO14 that you'll have to enable.  On the GW2348's R11 needs to be loaded.

Tim

----- Original Message ----
From: Ahmet Basagalar <ahmet at thebluezone.com>
To: avila <avila at lists.unixstudios.net>
Sent: Tuesday, August 22, 2006 2:28:13 PM
Subject: [Avila] GPIO 14 data output
Subject: [Avila] Hi all,

I want to use GPIO 14 to strobe the DS1819 hardware watchdog, but it is 
configured as a clock source by default. I want to change it to data output 
instead of clock but I could not find so far where "GPIO Clock Control 
Register (GPCLKR)" is set. Does anybody know which piece of code I need to 
modify for this purpose?

Thanks,
Ahmet 

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