mtfurlan
commented
1 year ago I made a very first pass dts shim that seems to work for my usecase.
dts/bindings/sensor/ublox,ubxlib-shim.yaml:
description: |
A shim to put ubxlib in the devicetree
compatible: "ublox,ubxlib-shim"
include: base.yaml
properties:
bus-type:
type: int
enum:
- 0
- 1
required: true
description: type of bus it's on, 0=spi, 1=i2c
bus-num:
type: int
required: true
description: what number bus it's on (4 for spi4, for example)
module-type:
type: int
enum:
- 0
- 1
- 2
required: true
description: What type of ublox module, M8=0, M9=1, M10=2devicetree overlay:
&spi4 {
compatible = "nordic,nrf-spim";
status = "okay";
cs-gpios = <&gpio0 17 GPIO_ACTIVE_LOW>;
pinctrl-0 = <&spi4_default>;
pinctrl-1 = <&spi4_sleep>;
pinctrl-names = "default", "sleep";
ublox: ublox@0 {
compatible = "ublox,ubxlib-shim";
reg = <0>;
bus-num = <4>;
bus-type = <0>; // 0 is spi, 1 is i2c
module-type = <1>; // 0 is M8, 1 is M9, 2 is M10
};
};main.c:
#define UBLOX DT_NODELABEL(ublox)
#ifdef UBLOX
#if DT_PROP(UBLOX, bus_type) == 0 // spi
#pragma message ( "spi" )
#define U_CFG_APP_GNSS_SPI DT_PROP(UBLOX, bus_num)
#elif DT_PROP(UBLOX, bus_type) == 1 // i2c
#pragma message ( "i2c" )
#define U_CFG_APP_GNSS_I2C DT_PROP(UBLOX, bus_num)
#else
#warning "bad ublox dts config"
#endif
#define U_CFG_TEST_GNSS_MODULE_TYPE DT_PROP(UBLOX, module_type)
#else
#warning "no ublox in dts?"
#endif
...
static const uDeviceCfg_t gDeviceCfg = {
.deviceType = U_DEVICE_TYPE_GNSS,
.deviceCfg = {
.cfgGnss = {
.moduleType = U_CFG_TEST_GNSS_MODULE_TYPE,
.pinEnablePower = -1,
.pinDataReady = -1, // Not used
},
},
#if defined(U_CFG_APP_GNSS_I2C) && (U_CFG_APP_GNSS_I2C >= 0)
.transportType = U_DEVICE_TRANSPORT_TYPE_I2C,
.transportCfg = {
.cfgI2c = {
.i2c = U_CFG_APP_GNSS_I2C,
.alreadyOpen = true
},
},
#endif
#if defined(U_CFG_APP_GNSS_SPI) && (U_CFG_APP_GNSS_SPI >= 0)
.transportType = U_DEVICE_TRANSPORT_TYPE_SPI,
.transportCfg = {
.cfgSpi = {
.spi = U_CFG_APP_GNSS_SPI,
.pinMosi = -1,
.pinMiso = -1,
.pinClk = -1,
.device = U_COMMON_SPI_CONTROLLER_DEVICE_INDEX_DEFAULTS(0)
},
},
# endif
};
I had spent a while trying to figure out how to get "4" out of the spi4 devicetree defines so you don't have to configure it into the shim, and I came to the conclusion you can't. And without doing string comparison on the "compatible" of the spi/i2c bus you can't figure out if it's spi/i2c, and the preprocessor doesn't want to do string comparisons.
It needs some extending to support things besides i2c and spi, and extended to support other configs like alternate i2c addresses, but I think this is our best approach for the short term.
This meets my needs, so while I'll definitely post if I come up with something better I'm probably just going to use this.
RobMeades
bperseghetti
beriberikix
bjarki-andreasen
ubxlib is not integrated with the devicetree model, this is confusing and limiting. Devicetree wants you to to have a device(on a bus) and load the driver based on the compatible string, while ubxlib wants you to setup the bus in the devicetree, put no device on it, and use preprocessor defines to select what bus to use.
Aside from being confusing, this makes supporting two boards that have different u-blox chips on different busses very difficult. For other things like status lights, I just configure the devicetree so that the LED named "gnss_fix" is on an IO expander on board A, on IO on board B, and the codebase doesn't need to know how it's connected. But for ubxlib, I have to additionally set some preprocessor flags to select the ublox bus and chip type in addition to telling zephyr which board devicetree to use.
The devicetree configuration stuff is available at compile time, so I suspect that a zephyr driver could handle converting the devicetree configs into the defines ubxlib is expecting. There would definitely be issues if someone tries to have two ublox modules connected, and probably some other edge cases because drivers are supposed to be self contained and pass around a pointer to a struct for all of the configuration (example)
I'll try to look into this more, but I'm doing this for a $work project that I'm being moved off of, so I can't promise much.