mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
288 lines
11 KiB
288 lines
11 KiB
============================================== |
|
MFP Configuration for PXA2xx/PXA3xx Processors |
|
============================================== |
|
|
|
Eric Miao <[email protected]> |
|
|
|
MFP stands for Multi-Function Pin, which is the pin-mux logic on PXA3xx and |
|
later PXA series processors. This document describes the existing MFP API, |
|
and how board/platform driver authors could make use of it. |
|
|
|
Basic Concept |
|
============= |
|
|
|
Unlike the GPIO alternate function settings on PXA25x and PXA27x, a new MFP |
|
mechanism is introduced from PXA3xx to completely move the pin-mux functions |
|
out of the GPIO controller. In addition to pin-mux configurations, the MFP |
|
also controls the low power state, driving strength, pull-up/down and event |
|
detection of each pin. Below is a diagram of internal connections between |
|
the MFP logic and the remaining SoC peripherals:: |
|
|
|
+--------+ |
|
| |--(GPIO19)--+ |
|
| GPIO | | |
|
| |--(GPIO...) | |
|
+--------+ | |
|
| +---------+ |
|
+--------+ +------>| | |
|
| PWM2 |--(PWM_OUT)-------->| MFP | |
|
+--------+ +------>| |-------> to external PAD |
|
| +---->| | |
|
+--------+ | | +-->| | |
|
| SSP2 |---(TXD)----+ | | +---------+ |
|
+--------+ | | |
|
| | |
|
+--------+ | | |
|
| Keypad |--(MKOUT4)----+ | |
|
+--------+ | |
|
| |
|
+--------+ | |
|
| UART2 |---(TXD)--------+ |
|
+--------+ |
|
|
|
NOTE: the external pad is named as MFP_PIN_GPIO19, it doesn't necessarily |
|
mean it's dedicated for GPIO19, only as a hint that internally this pin |
|
can be routed from GPIO19 of the GPIO controller. |
|
|
|
To better understand the change from PXA25x/PXA27x GPIO alternate function |
|
to this new MFP mechanism, here are several key points: |
|
|
|
1. GPIO controller on PXA3xx is now a dedicated controller, same as other |
|
internal controllers like PWM, SSP and UART, with 128 internal signals |
|
which can be routed to external through one or more MFPs (e.g. GPIO<0> |
|
can be routed through either MFP_PIN_GPIO0 as well as MFP_PIN_GPIO0_2, |
|
see arch/arm/mach-pxa/mfp-pxa300.h) |
|
|
|
2. Alternate function configuration is removed from this GPIO controller, |
|
the remaining functions are pure GPIO-specific, i.e. |
|
|
|
- GPIO signal level control |
|
- GPIO direction control |
|
- GPIO level change detection |
|
|
|
3. Low power state for each pin is now controlled by MFP, this means the |
|
PGSRx registers on PXA2xx are now useless on PXA3xx |
|
|
|
4. Wakeup detection is now controlled by MFP, PWER does not control the |
|
wakeup from GPIO(s) any more, depending on the sleeping state, ADxER |
|
(as defined in pxa3xx-regs.h) controls the wakeup from MFP |
|
|
|
NOTE: with such a clear separation of MFP and GPIO, by GPIO<xx> we normally |
|
mean it is a GPIO signal, and by MFP<xxx> or pin xxx, we mean a physical |
|
pad (or ball). |
|
|
|
MFP API Usage |
|
============= |
|
|
|
For board code writers, here are some guidelines: |
|
|
|
1. include ONE of the following header files in your <board>.c: |
|
|
|
- #include "mfp-pxa25x.h" |
|
- #include "mfp-pxa27x.h" |
|
- #include "mfp-pxa300.h" |
|
- #include "mfp-pxa320.h" |
|
- #include "mfp-pxa930.h" |
|
|
|
NOTE: only one file in your <board>.c, depending on the processors used, |
|
because pin configuration definitions may conflict in these file (i.e. |
|
same name, different meaning and settings on different processors). E.g. |
|
for zylonite platform, which support both PXA300/PXA310 and PXA320, two |
|
separate files are introduced: zylonite_pxa300.c and zylonite_pxa320.c |
|
(in addition to handle MFP configuration differences, they also handle |
|
the other differences between the two combinations). |
|
|
|
NOTE: PXA300 and PXA310 are almost identical in pin configurations (with |
|
PXA310 supporting some additional ones), thus the difference is actually |
|
covered in a single mfp-pxa300.h. |
|
|
|
2. prepare an array for the initial pin configurations, e.g.:: |
|
|
|
static unsigned long mainstone_pin_config[] __initdata = { |
|
/* Chip Select */ |
|
GPIO15_nCS_1, |
|
|
|
/* LCD - 16bpp Active TFT */ |
|
GPIOxx_TFT_LCD_16BPP, |
|
GPIO16_PWM0_OUT, /* Backlight */ |
|
|
|
/* MMC */ |
|
GPIO32_MMC_CLK, |
|
GPIO112_MMC_CMD, |
|
GPIO92_MMC_DAT_0, |
|
GPIO109_MMC_DAT_1, |
|
GPIO110_MMC_DAT_2, |
|
GPIO111_MMC_DAT_3, |
|
|
|
... |
|
|
|
/* GPIO */ |
|
GPIO1_GPIO | WAKEUP_ON_EDGE_BOTH, |
|
}; |
|
|
|
a) once the pin configurations are passed to pxa{2xx,3xx}_mfp_config(), |
|
and written to the actual registers, they are useless and may discard, |
|
adding '__initdata' will help save some additional bytes here. |
|
|
|
b) when there is only one possible pin configurations for a component, |
|
some simplified definitions can be used, e.g. GPIOxx_TFT_LCD_16BPP on |
|
PXA25x and PXA27x processors |
|
|
|
c) if by board design, a pin can be configured to wake up the system |
|
from low power state, it can be 'OR'ed with any of: |
|
|
|
WAKEUP_ON_EDGE_BOTH |
|
WAKEUP_ON_EDGE_RISE |
|
WAKEUP_ON_EDGE_FALL |
|
WAKEUP_ON_LEVEL_HIGH - specifically for enabling of keypad GPIOs, |
|
|
|
to indicate that this pin has the capability of wake-up the system, |
|
and on which edge(s). This, however, doesn't necessarily mean the |
|
pin _will_ wakeup the system, it will only when set_irq_wake() is |
|
invoked with the corresponding GPIO IRQ (GPIO_IRQ(xx) or gpio_to_irq()) |
|
and eventually calls gpio_set_wake() for the actual register setting. |
|
|
|
d) although PXA3xx MFP supports edge detection on each pin, the |
|
internal logic will only wakeup the system when those specific bits |
|
in ADxER registers are set, which can be well mapped to the |
|
corresponding peripheral, thus set_irq_wake() can be called with |
|
the peripheral IRQ to enable the wakeup. |
|
|
|
|
|
MFP on PXA3xx |
|
============= |
|
|
|
Every external I/O pad on PXA3xx (excluding those for special purpose) has |
|
one MFP logic associated, and is controlled by one MFP register (MFPR). |
|
|
|
The MFPR has the following bit definitions (for PXA300/PXA310/PXA320):: |
|
|
|
31 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 |
|
+-------------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
|
| RESERVED |PS|PU|PD| DRIVE |SS|SD|SO|EC|EF|ER|--| AF_SEL | |
|
+-------------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
|
|
|
Bit 3: RESERVED |
|
Bit 4: EDGE_RISE_EN - enable detection of rising edge on this pin |
|
Bit 5: EDGE_FALL_EN - enable detection of falling edge on this pin |
|
Bit 6: EDGE_CLEAR - disable edge detection on this pin |
|
Bit 7: SLEEP_OE_N - enable outputs during low power modes |
|
Bit 8: SLEEP_DATA - output data on the pin during low power modes |
|
Bit 9: SLEEP_SEL - selection control for low power modes signals |
|
Bit 13: PULLDOWN_EN - enable the internal pull-down resistor on this pin |
|
Bit 14: PULLUP_EN - enable the internal pull-up resistor on this pin |
|
Bit 15: PULL_SEL - pull state controlled by selected alternate function |
|
(0) or by PULL{UP,DOWN}_EN bits (1) |
|
|
|
Bit 0 - 2: AF_SEL - alternate function selection, 8 possibilities, from 0-7 |
|
Bit 10-12: DRIVE - drive strength and slew rate |
|
0b000 - fast 1mA |
|
0b001 - fast 2mA |
|
0b002 - fast 3mA |
|
0b003 - fast 4mA |
|
0b004 - slow 6mA |
|
0b005 - fast 6mA |
|
0b006 - slow 10mA |
|
0b007 - fast 10mA |
|
|
|
MFP Design for PXA2xx/PXA3xx |
|
============================ |
|
|
|
Due to the difference of pin-mux handling between PXA2xx and PXA3xx, a unified |
|
MFP API is introduced to cover both series of processors. |
|
|
|
The basic idea of this design is to introduce definitions for all possible pin |
|
configurations, these definitions are processor and platform independent, and |
|
the actual API invoked to convert these definitions into register settings and |
|
make them effective there-after. |
|
|
|
Files Involved |
|
-------------- |
|
|
|
- arch/arm/mach-pxa/include/mach/mfp.h |
|
|
|
for |
|
1. Unified pin definitions - enum constants for all configurable pins |
|
2. processor-neutral bit definitions for a possible MFP configuration |
|
|
|
- arch/arm/mach-pxa/mfp-pxa3xx.h |
|
|
|
for PXA3xx specific MFPR register bit definitions and PXA3xx common pin |
|
configurations |
|
|
|
- arch/arm/mach-pxa/mfp-pxa2xx.h |
|
|
|
for PXA2xx specific definitions and PXA25x/PXA27x common pin configurations |
|
|
|
- arch/arm/mach-pxa/mfp-pxa25x.h |
|
arch/arm/mach-pxa/mfp-pxa27x.h |
|
arch/arm/mach-pxa/mfp-pxa300.h |
|
arch/arm/mach-pxa/mfp-pxa320.h |
|
arch/arm/mach-pxa/mfp-pxa930.h |
|
|
|
for processor specific definitions |
|
|
|
- arch/arm/mach-pxa/mfp-pxa3xx.c |
|
- arch/arm/mach-pxa/mfp-pxa2xx.c |
|
|
|
for implementation of the pin configuration to take effect for the actual |
|
processor. |
|
|
|
Pin Configuration |
|
----------------- |
|
|
|
The following comments are copied from mfp.h (see the actual source code |
|
for most updated info):: |
|
|
|
/* |
|
* a possible MFP configuration is represented by a 32-bit integer |
|
* |
|
* bit 0.. 9 - MFP Pin Number (1024 Pins Maximum) |
|
* bit 10..12 - Alternate Function Selection |
|
* bit 13..15 - Drive Strength |
|
* bit 16..18 - Low Power Mode State |
|
* bit 19..20 - Low Power Mode Edge Detection |
|
* bit 21..22 - Run Mode Pull State |
|
* |
|
* to facilitate the definition, the following macros are provided |
|
* |
|
* MFP_CFG_DEFAULT - default MFP configuration value, with |
|
* alternate function = 0, |
|
* drive strength = fast 3mA (MFP_DS03X) |
|
* low power mode = default |
|
* edge detection = none |
|
* |
|
* MFP_CFG - default MFPR value with alternate function |
|
* MFP_CFG_DRV - default MFPR value with alternate function and |
|
* pin drive strength |
|
* MFP_CFG_LPM - default MFPR value with alternate function and |
|
* low power mode |
|
* MFP_CFG_X - default MFPR value with alternate function, |
|
* pin drive strength and low power mode |
|
*/ |
|
|
|
Examples of pin configurations are:: |
|
|
|
#define GPIO94_SSP3_RXD MFP_CFG_X(GPIO94, AF1, DS08X, FLOAT) |
|
|
|
which reads GPIO94 can be configured as SSP3_RXD, with alternate function |
|
selection of 1, driving strength of 0b101, and a float state in low power |
|
modes. |
|
|
|
NOTE: this is the default setting of this pin being configured as SSP3_RXD |
|
which can be modified a bit in board code, though it is not recommended to |
|
do so, simply because this default setting is usually carefully encoded, |
|
and is supposed to work in most cases. |
|
|
|
Register Settings |
|
----------------- |
|
|
|
Register settings on PXA3xx for a pin configuration is actually very |
|
straight-forward, most bits can be converted directly into MFPR value |
|
in a easier way. Two sets of MFPR values are calculated: the run-time |
|
ones and the low power mode ones, to allow different settings. |
|
|
|
The conversion from a generic pin configuration to the actual register |
|
settings on PXA2xx is a bit complicated: many registers are involved, |
|
including GAFRx, GPDRx, PGSRx, PWER, PKWR, PFER and PRER. Please see |
|
mfp-pxa2xx.c for how the conversion is made.
|
|
|