Move MTAC-PULSE to GPIO descriptor library in the kernelHEAD2.0.0master

1 files changed, 28 insertions, 5 deletions

diff --git a/README b/README
index fa298b0..787c4ff 100644
--- a/README
+++ b/README
@@ -6,11 +6,34 @@ This driver requires the mtac.ko driver
 loaded first.  depmod should take care
 of this.
 
-Documentation for this board is here:
+This driver used to attempt to set "open drain" from
+the GPIO driver. This is not allowed by the Atmel
+GPIO driver.  In newer kernels it warns that this
+does not work. Open drain must be set by the
+Atmel pinctrl driver for Atmel GPIO controllers.
 
-http://www.multitech.net/developer/software/mlinux/using-mlinux/mlinux-using-accessory-cards/mtac-pulse-usage/
+Atmel calls "Open Drain" "MultiDriver".
 
-An init script can look in:
-/lib/modules/$(uname -r)/extra/mtac_xdot.ko
+The lack of multidrive was verified in
+kernel 3.12.70, mLinux 4.1.1 with MTAC-PULSE-BP
+in slot AP1. The pin for AP1_NRESET is PB12.
+The AP2_NRESET is PB13.
 
-to find the driver.
+The device address for PIOB is 0xFFFF F600.
+The offset for register PIO_MDSR is 0x58.
+PIO_MDSR is Multi-Driver Status Register, and
+Multi-Driver is what Atmel calls Open Drain.
+
+   mtcdt:/home/mtadm# devmem2 0xfffff658                                                                                                                                                                            * /dev/mem opened.
+   Memory mapped at address 0xb6f35000.
+   Read at address  0xFFFFF658 (0xb6f35658): 0x00000000
+
+This says that in 4.1.1 mLinux, no outputs for PIOB 
+are set to multi-driver.
+
+   mtcdt:/sys/devices/platform/mts-io/ap1# cat hw-version
+   MTAC-PULSE-0.0
+
+pinctrl settings must be done in device tree for Atmel
+processors when trying to set pull-up, pull-down, or
+multi-drive.