Spi device tree source code
2022-08-11 Thursday
Notes on SPI device tree source, with goal to add SPI device to modified RPi Pico DTS files, which build firmware to run on Sparkfun DEV-18288 board. An interesting link at Nordic Semi documentation pages, link to page which mentions Synopsis as designer of designware-spi device bindings and related bindings is:
- https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.5.1/zephyr/reference/devicetree/bindings.html
Contents
SPI dts examples
In Zephyr RTOS' supported board dts files we find SPI peripherals defined for several boards. Here are excerpts
Excerpt 1 - zephyr/boards/arm/sparkfun_thing_plus_nrf9160/sparkfun_thing_plus_nrf9160_common.dts
142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 |
&spi3 {
compatible = "nordic,nrf-spim";
status = "okay";
cs-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;
pinctrl-0 = <&spi3_default>;
pinctrl-1 = <&spi3_sleep>;
pinctrl-names = "default", "sleep";
w25q32jv: w25q32jv@0 {
compatible = "jedec,spi-nor";
label = "W25Q32JV";
reg = <0>;
spi-max-frequency = <40000000>;
wp-gpios = <&gpio0 8 GPIO_ACTIVE_LOW>;
hold-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
size = <0x2000000>;
has-dpd;
t-enter-dpd = <3000>;
t-exit-dpd = <30000>;
jedec-id = [ ef 40 16 ];
};
};
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a |
81 spi3_default: spi3_default {
82 group1 {
83 psels = <NRF_PSEL(SPIM_SCK, 0, 11)>,
84 <NRF_PSEL(SPIM_MOSI, 0, 9)>,
85 <NRF_PSEL(SPIM_MISO, 0, 28)>;
86 };
87 };
88
89 spi3_sleep: spi3_sleep {
90 group1 {
91 psels = <NRF_PSEL(SPIM_SCK, 0, 11)>,
92 <NRF_PSEL(SPIM_MOSI, 0, 9)>,
93 <NRF_PSEL(SPIM_MISO, 0, 28)>;
94 low-power-enable;
95 };
96 };
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^ edit point dts excerpt 2
Excerpt 2 - zephyr/boards/arm/96b_carbon_nrf51/96b_carbon_nrf51.dts and 96b_carbon_nrf51-pinctrl.dtsi
47 48 49 50 51 52 53 54 55 56 |
&spi1 {
compatible = "nordic,nrf-spis";
status = "okay";
def-char = <0x00>;
pinctrl-0 = <&spi1_default>;
pinctrl-names = "default";
bt-hci@0 {
compatible = "zephyr,bt-hci-spi-slave";
reg = <0>;
irq-gpios = <&gpio0 28 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
};
};
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37 38 39 40 41 42 43 44 |
spi1_default: spi1_default {
group1 {
psels = <NRF_PSEL(SPIS_SCK, 0, 7)>,
<NRF_PSEL(SPIS_MOSI, 0, 0)>,
<NRF_PSEL(SPIS_MISO, 0, 30)>,
<NRF_PSEL(SPIS_CSN, 0, 25)>;
};
};
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^ edit point dts excerpt 3
Excerpt 3 - zephyr/boards/arm/stm32l562e_dk/stm32l562e_dk_common.dts and stm32l562e_dk_common.dtsi
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Looks like pin control names value 'default' may be defined in Kconfig.default for this board . . . |
114 115 116 117 118 119 120 121 122 123 124 125 126 127 |
&spi1 {
pinctrl-0 = <&spi1_sck_pg2 &spi1_miso_pg3 &spi1_mosi_pg4>;
pinctrl-names = "default";
cs-gpios = <&gpiog 5 (GPIO_ACTIVE_HIGH | GPIO_PULL_UP)>;
status = "okay";
spbtle-rf@0 {
compatible = "zephyr,bt-hci-spi";
reg = <0>;
irq-gpios = <&gpiog 6 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
reset-gpios = <&gpiog 8 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
spi-max-frequency = <2000000>;
label = "SPBTLE-RF";
};
};
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^ edit point dts excerpt 4
Excerpt 4 -
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^ edit point dts excerpt 5
Excerpt 5 -
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^ edit point dts excerpt 5
From the zephyr/boards/arm/rpi_pico/doc/index.rst file:
== [[#top|^]] edit point dts excerpt 5 == 37 Raspberry Pi Pico (Image courtesy of Raspberry Pi) 38 39 Supported Features 40 ================== 41 42 The rpi_pico board configuration supports the following 43 hardware features: 44 45 .. list-table:: 46 :header-rows: 1 47 48 * - Peripheral 49 - Kconfig option 50 - Devicetree compatible 51 * - NVIC 52 - N/A 53 - :dtcompatible:`arm,v6m-nvic` 54 * - UART 55 - :kconfig:option:`CONFIG_SERIAL` 56 - :dtcompatible:`rpi,pico-uart` 57 * - GPIO 58 - :kconfig:option:`CONFIG_GPIO` 59 - :dtcompatible:`rpi,pico-gpio` 60 * - I2C 61 - :kconfig:option:`CONFIG_I2C` 62 - :dtcompatible:`snps,designware-i2c` 63 * - USB Device 64 - :kconfig:option:`CONFIG_USB_DEVICE_STACK` 65 - :dtcompatible:`raspberrypi,pico-usbd` 66 * - HWINFO 67 - :kconfig:option:`CONFIG_HWINFO` 68 - N/A 69 70 Programming and Debugging 71 ************************* 72 73 Flashing
There is a clue here on line 62 "- :dtcompatible:`snps,designware-i2c`". This is for I2C, but a search via startpage.com for "snps,designware-spi" gives a first or near first result of:
This still leaves the open question, where are RPi Pico's I2C and SPI driver implementations in Zephyr RTOS release 3.1.0?
^ YAML device bindings files
To support a typical development kit or custom board with multiple peripherals we need a device bindings file comparable to this ... bindings file:
- ~/projects-sandbox/workspace-for-rpi/zephyr/boards/arm/nrf9160dk_nrf9160/nrf9160dk_nrf9160.yaml
identifier: nrf9160dk_nrf9160 name: nRF9160-DK-NRF9160 type: mcu arch: arm toolchain: - gnuarmemb - xtools - zephyr ram: 88 flash: 256 supported: - arduino_gpio - arduino_i2c - gpio - i2c - pwm - spi - watchdog - counter
Or possibly this bindings file by Jared Wolff of Circuit Dojo:
