avr32: improve NGW100 I2C/PMBus setup

Basic I2C initialization for the NGW100 board:

  - Provide empty i2c device table. Daughtercards may add devices,
    and the ATtiny24 could do stuff too.

  - Set up EXTINT(3) so the ATtiny24 can interrupt the AP7000.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NHaavard Skinnemoen <haavard.skinnemoen@atmel.com>

arch/avr32/boards/atngw100/setup.c

@@ -9,6 +9,8 @@
  */
 #include <linux/clk.h>
 #include <linux/etherdevice.h>
+#include <linux/irq.h>
+#include <linux/i2c.h>
 #include <linux/i2c-gpio.h>
 #include <linux/init.h>
 #include <linux/linkage.h>
@@ -147,6 +149,10 @@ static struct platform_device i2c_gpio_device = {
 	},
 };
 
+static struct i2c_board_info __initdata i2c_info[] = {
+	/* NOTE:  original ATtiny24 firmware is at address 0x0b */
+};
+
 static int __init atngw100_init(void)
 {
 	unsigned	i;
@@ -172,12 +178,28 @@ static int __init atngw100_init(void)
 	}
 	platform_device_register(&ngw_gpio_leds);
 
+	/* all these i2c/smbus pins should have external pullups for
+	 * open-drain sharing among all I2C devices.  SDA and SCL do;
+	 * PB28/EXTINT3 doesn't; it should be SMBALERT# (for PMBus),
+	 * but it's not available off-board.
+	 */
+	at32_select_periph(GPIO_PIN_PB(28), 0, AT32_GPIOF_PULLUP);
 	at32_select_gpio(i2c_gpio_data.sda_pin,
 		AT32_GPIOF_MULTIDRV | AT32_GPIOF_OUTPUT | AT32_GPIOF_HIGH);
 	at32_select_gpio(i2c_gpio_data.scl_pin,
 		AT32_GPIOF_MULTIDRV | AT32_GPIOF_OUTPUT | AT32_GPIOF_HIGH);
 	platform_device_register(&i2c_gpio_device);
+	i2c_register_board_info(0, i2c_info, ARRAY_SIZE(i2c_info));
 
 	return 0;
 }
 postcore_initcall(atngw100_init);
+
+static int __init atngw100_arch_init(void)
+{
+	/* set_irq_type() after the arch_initcall for EIC has run, and
+	 * before the I2C subsystem could try using this IRQ.
+	 */
+	return set_irq_type(AT32_EXTINT(3), IRQ_TYPE_EDGE_FALLING);
+}
+arch_initcall(atngw100_arch_init);