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Update to Zephyr best practices as of May 2024
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Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>
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@gmarull
gmarull committed May 21, 2024
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71 changes: 25 additions & 46 deletions slides.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@
}{Gerard Marull-Paretas}
}
\institute{Nordic Semiconductor ASA}
\date{7\textsuperscript{th} June 2022}
\date{20\textsuperscript{th} May 2024}

% document ---------------------------------------------------------------------

Expand Down Expand Up @@ -173,19 +173,16 @@ \subsection{Devicetree}
soc {
i2c0: i2c@40003000 {
compatible = "nordic,nrf-twim";
label = "I2C0";
reg = <0x40003000 0x1000>;

apds9960@39 {
compatible = "avago,apds9960";
label = "APDS9960";
reg = <0x39>;
};

ti_hdc@43 {
compatible = "ti,hdc",
"ti,hdc1010";
label = "HDC1010";
reg = <0x43>;
};
};
Expand Down Expand Up @@ -245,14 +242,12 @@ \subsection{Devicetree}
\texttt{compatible} & %
Name of the \textbf{hardware} a node \textbf{represents}, typically
\texttt{vendor,device}. Used to find the \textbf{bindings} for the node. \\
\texttt{label} & %
\textbf{Name} of the device (unique). \\
\texttt{reg} & %
Information used to \textbf{address} the device (optional). Value
meaning depends on the device. In general, it is a
\textbf{sequence of address-length pairs.} \\
\texttt{status} & %
\textbf{Status} of the device. \texttt{okay} (default if not specified)
\textbf{Status} of the device.\ \texttt{okay} (default if not specified)
or \texttt{disabled}. \\
\bottomrule
\end{tabular}
Expand Down Expand Up @@ -298,15 +293,13 @@ \subsection{Devicetree}
/* one instance of 'nordic,nrf-twim' */
i2c0: i2c@40003000 {
compatible = "nordic,nrf-twim";
label = "I2C_0";
reg = <0x40003000 0x1000>;
clock-frequency = <I2C_BITRATE_STANDARD>;
};

/* another instance of 'nordic,nrf-twim' */
i2c1: i2c@40004000 {
compatible = "nordic,nrf-twim"
label = "I2C_1";
reg = <0x40004000 0x1000>;
clock-frequency = <I2C_BITRATE_FAST>;
};
Expand Down Expand Up @@ -426,7 +419,7 @@ \subsection{Devicetree}
\item \textbf{Content} of Devicetree, including data types, is
\textbf{described} in \textbf{binding} files
\item Binding files are used by the Devicetree parser to
\textbf{validate content}
\textbf{validate content} (i.e.\ schema)
\item Binding files are written in \textbf{YAML}, structure custom to
Zephyr
\end{itemize}
Expand All @@ -452,8 +445,7 @@ \subsection{Devicetree}
/ {
dev0: dev@deadbeef {
?\tikzmark{dtcompat}?compatible = "vnd,dev"
?\tikzmark{dtbaseprop1}?label = "DEV0";
?\tikzmark{dtbaseprop2}?reg = <0xdeadbeef>;
?\tikzmark{dtbaseprop}?reg = <0xdeadbeef>;
?\tikzmark{dtprop}?foo = <7>;
};
};
Expand All @@ -465,8 +457,7 @@ \subsection{Devicetree}

\begin{tikzpicture}[overlay,remember picture]
\draw[->] (pic cs:dtcompat) to[out=180,in=0] (pic cs:bindingcompat);
\draw[->] (pic cs:dtbaseprop1) to[out=180,in=0] (pic cs:bindingbaseprop);
\draw[->] (pic cs:dtbaseprop2) to[out=180,in=0] (pic cs:bindingbaseprop);
\draw[->] (pic cs:dtbaseprop) to[out=180,in=0] (pic cs:bindingbaseprop);
\draw[->] (pic cs:dtprop) to[out=180,in=0] (pic cs:bindingprop);
\end{tikzpicture}
\end{frame}
Expand Down Expand Up @@ -794,7 +785,7 @@ \subsection{Zephyr devices}
struct device {
const char *name;
const void *config;
void * const data;
void * data;
const void *api;
...
};
Expand All @@ -810,14 +801,12 @@ \subsection{Zephyr devices}
Field & Purpose \\
\midrule
\texttt{name} & %
Device name (unique), corresponds to the \textbf{\texttt{label}}
property for Devicetree devices \\
Device name (unique), corresponds to the Devicetree node name \\
\texttt{config} & %
Reference to \textbf{read-only configuration} set at
\textbf{compile time}, tipically used to store Devicetree properties \\
Reference to \textbf{immutable device configuration}, tipically used to
store Devicetree properties \\
\texttt{data} & %
Reference to device \textbf{data} that needs to be modified at
\textbf{runtime}, e.g.\ counter, state, etc. \\
Reference to \textbf{mutable device data}, e.g.\ counter, state, etc.\\
\texttt{api} & %
Reference to the device \textbf{API operations} \\
\bottomrule
Expand Down Expand Up @@ -996,7 +985,6 @@ \subsection{Example device driver}
...
accel: sensor@ff {
compatible = "vnd,mysensor";
label = "ACCEL"
reg = <0xff>;
int-gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
sample-freq = <1000>;
Expand Down Expand Up @@ -1035,7 +1023,7 @@ \subsection{Example device driver}
const struct device *dev = DEVICE_DT_GET_ONE(vnd_my_sensor);

/* get reference to a device at runtime, using name lookup */
const struct device *dev = device_get_binding("ACCEL");
const struct device *dev = device_get_binding("sensor@ff");
\end{minted}
\caption{Examples on how to obtain device references}
\end{listing}
Expand Down Expand Up @@ -1568,8 +1556,10 @@ \subsection{Coding session: JM-101 driver}
config JM101
bool "JM-101 fingerprint sensor"
default y
?\tikzmark{depends}?depends on GPIO && SERIAL && UART_INTERRUPT_DRIVEN && \
DT_HAS_ZEANTEC_JM101_ENABLED?\tikzmark{default}?
depends on DT_HAS_ZEANTEC_JM101_ENABLED?\tikzmark{default}?
?\tikzmark{select}?select GPIO
select SERIAL
select UART_INTERRUPT_DRIVEN
help
JM-101 fingerprint sensor.

Expand All @@ -1584,8 +1574,8 @@ \subsection{Coding session: JM-101 driver}
\end{listing}

\begin{tikzpicture}[overlay,remember picture]
\draw[->] ($(pic cs:depends) +(-2ex,4.7em)$) to[out=180,in=180] (pic cs:depends);
\node[anchor=west] at ($(pic cs:depends) +(-2ex,4.7em)$) {Software Dependencies};
\draw[->] ($(pic cs:select) +(-2ex,6em)$) to[out=180,in=180] (pic cs:select);
\node[anchor=west] at ($(pic cs:select) +(-2ex,6em)$) {Software Dependencies (selected)};
\draw[->] ($(pic cs:default) +(5ex,3.5em)$) to[out=270,in=0] (pic cs:default);
\node[anchor=south] at ($(pic cs:default) +(5ex,3.5em)$) {Depends on being enabled in DT};
\end{tikzpicture}
Expand Down Expand Up @@ -1755,7 +1745,7 @@ \subsection{Coding session: JM-101 driver}
...
#ifdef CONFIG_JM101_TRIGGER
if (config->touch.port != NULL) {
if (!device_is_ready(config->touch.port)) {
if (!gpio_is_ready_dt(&config->touch)) {
LOG_ERR("Touch GPIO controller not ready");
return -ENODEV;
}
Expand Down Expand Up @@ -1835,18 +1825,12 @@ \subsection{Using the JM-101 driver}
\item JM-101 sensor driver is enabled when \texttt{CONFIG\_JM101=y}
\item \texttt{CONFIG\_JM101} is automatically enabled if:
\begin{itemize}
\item All its \textbf{dependencies} are \textbf{enabled}, including
\texttt{CONFIG\_SENSOR}
\item Its driver class is enabledm i.e.\ \texttt{CONFIG\_SENSOR}
\item One or more instances are \texttt{okay} in Devicetree
\end{itemize}
\end{itemize}
\begin{listing}[H]
\begin{minted}[fontsize=\tiny]{kconfig}
# dependencies required so that JM-101 driver can be enabled
CONFIG_GPIO=y
CONFIG_SERIAL=y
CONFIG_UART_INTERRUPT_DRIVEN=y

# enable the sensor driver class
CONFIG_SENSOR=y

Expand Down Expand Up @@ -2439,7 +2423,9 @@ \subsection{Coding session: servo-driven lock}
config LOCK_SERVO
bool "Servo-controlled lock"
default y
depends on PWM && ADC && DT_HAS_LOCK_SERVO_ENABLED
depends on DT_HAS_LOCK_SERVO_ENABLED
select PWM
select ADC
help
Enables a servo-controlled lock driver.

Expand All @@ -2456,10 +2442,8 @@ \subsection{Coding session: servo-driven lock}
add_subdirectory(drivers)

zephyr_include_directories(include)

# optional, only needed for userspace support
list(APPEND SYSCALL_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/include)
set(SYSCALL_INCLUDE_DIRS ${SYSCALL_INCLUDE_DIRS} PARENT_SCOPE)
zephyr_syscall_include_directories(include)
\end{minted}
\caption{\texttt{\$ROOT/CMakeLists.txt}}
\end{listing}
Expand Down Expand Up @@ -2560,7 +2544,7 @@ \subsection{Using the servo-driven lock driver}
closed-pulse-us = <1250>;
io-channels = <&adc 0>;
fb-gain = <(-1765)>;
fb-offset = <4206250>;
fb-offset-microvolt = <4206250>;
max-target-err-us = <50>;
max-action-time-ms = <2000>;
};
Expand Down Expand Up @@ -2627,17 +2611,12 @@ \subsection{Using the servo-driven lock driver}
\texttt{CONFIG\_LOCK\_SERVO=y}
\item \texttt{CONFIG\_LOCK\_SERVO} is automatically enabled if:
\begin{itemize}
\item All its \textbf{dependencies} are \textbf{enabled}, including
\texttt{CONFIG\_LOCK}
\item Its driver class is enabled, i.e.\ \texttt{CONFIG\_LOCK}
\item One or more instances are \texttt{okay} in Devicetree
\end{itemize}
\end{itemize}
\begin{listing}[H]
\begin{minted}[fontsize=\tiny]{kconfig}
# dependencies required so that servo-driven lock driver can be enabled
CONFIG_ADC=y
CONFIG_PWM=y

# enable the lock driver class
CONFIG_LOCK=y
\end{minted}
Expand Down

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