ADC timeout on Overo

I'm trying to enable ADC measurements on an Overo/Summit system running Linux 2.6.28. I started with a fresh git pull of 2.6.28. I added what I thought was the appropriate code to the Overo specific initialization:

@@ -152,6 +152,10 @@ static struct twl4030_gpio_platform_data overo_gpio_data =
        .irq_end        = TWL4030_GPIO_IRQ_END,
 };
 
+static struct twl4030_madc_platform_data overo_madc_data = {
+       .irq_line       = 1,
+};
+
 static struct twl4030_usb_data overo_usb_data = {
        .usb_mode       = T2_USB_MODE_ULPI,
 };

@@ -162,6 +166,7 @@ static struct twl4030_platform_data overo_twldata = {
        .gpio           = &overo_gpio_data,
        .usb            = &overo_usb_data,
        .power          = GENERIC3430_T2SCRIPTS_DATA,
+        .madc           = &overo_madc_data,
 };
 

I built the kernel and the MADC driver module (twl4030-madc.ko). After inserting the module, the file twl4030-madc showed up in /dev. So far, so good. I coded a small user space application that issued a raw read ioctl for adc channel 3. The read timed out, as did reads for all other channels I tried. I did some preliminary debug of the driver and found that the reason for the failure is that once the ADC conversion starts, the EOC_SW1 bit in the CTRL_SW1 register (the indicator of completion) never goes to 1. Further debug shows that in the module initialization routine twl4030_madc_set_power, as soon as the MADC is powered on by setting CTRL1[0] MADCON bit to 1, the BUSY bit of CTRL_SW1 turns on and never turns off. I'm guessing this constant state of busy is why the conversion never completes. This leads me to believe that the MADC is not set up properly. Steve Sakoman confirmed that the HFCLKIN signal is 26 MHz for the Overo, so it does not look like a clock setup problem. Any ideas as to why the BUSY bit comes on and never turns off? Any other ideas?

regards,
frank

I'm still having the same problem with the conversion never completing, but my initial debug analysis was wrong. The BUSY bit does not turn on when power is applied. BUSY turns on when the conversion is started. The conversion never completes (BUSY never turns off). BUSY can only be reset with a power cycle (removing and reinserting the driver does not clear BUSY).

Im trying to understand if this is a driver problem or something specific to the Overo. Can anyone with one of the boards that has support enabled for the twl4030 driver (EVM2, EVM3, LDP and 2340/3430sdp)confirm the status of ADC on that board? If it's functional, what is the Linux revision of the working driver?

regards,
frank

Can I assume that since no one has confirmed ADC working on any of the boards using the twl4030 driver that it means that ADC is not working on any of those boards?

frank