diff options
| -rw-r--r-- | board/cr50/gpio.inc | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/board/cr50/gpio.inc b/board/cr50/gpio.inc index f279bf7cf9..0ea1800800 100644 --- a/board/cr50/gpio.inc +++ b/board/cr50/gpio.inc @@ -4,6 +4,43 @@ * found in the LICENSE file. */ +/* + * This file describes GPIO mapping for the cr50 code running on the H1 chip. + * + * For the purposes of this file H1 core has the following logical and + * physical items and properties: + * + * - 32 internal GPIOs, which are split into two ports of 16 bits each. + * Ports' architecture and programmig is described in "ARM Cortex-M System + * Design Kit TRM" DDIO47B. + * + * - a set of peripherals - slave and master SPI and I2C controllers, UARTs, + * interrupt controller, etc. + * + * - 28 pins on the package named DIOA0..14, DIOB0..7 and DIOM0..4 + * + * - a PINMUX - a unit which allows to interconnect objects from the three + * groups listed above. Note that some peripherals are attached to some + * pins directly, so in case those peripherals are used the pins should + * not be connected by PINMUX to any other outputs. + * + * The below macros are somewhat misleading (apparently for historical + * reasons), as PIN(p, b) component in fact refers not to the external pin, + * but to the GPIO (bit b on port p), where bit is in 0..15 range, and port is + * in 0..1 range. + * + * To describe routing of an external signal two macro instantiations are + * required: + * + * The GPIO_INT() or GPIO() macro assigns the signal a name and assigns it to + * the internal GPIO port, (again, defining the port using the PIN(port, bit) + * component of the macro invocation). GPIO_INT definitions assign their + * respective signals to interrupts and ISRs. + * + * The PINMUX macro assigns the previously defined GPIO to another object, + * most commonly to an external pin, but possibly to some internal component. + */ + /* Declare symbolic names for all the GPIOs that we care about. * Note: Those with interrupt handlers must be declared first. */ |