[bootlin/training-materials updates] master: Kernel course: misc improvements (1bfd6f99)
Michael Opdenacker
michael.opdenacker at bootlin.com
Wed Feb 3 13:27:50 CET 2021
Repository : https://github.com/bootlin/training-materials
On branch : master
Link : https://github.com/bootlin/training-materials/commit/1bfd6f99a8d6b1911b90013640474d2435430b17
>---------------------------------------------------------------
commit 1bfd6f99a8d6b1911b90013640474d2435430b17
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date: Wed Feb 3 13:27:50 2021 +0100
Kernel course: misc improvements
Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>
>---------------------------------------------------------------
1bfd6f99a8d6b1911b90013640474d2435430b17
.../kernel-i2c-device-model.tex | 0
slides/kernel-device-model/kernel-device-model.tex | 4 +-
slides/kernel-frameworks/kernel-frameworks.tex | 4 +-
slides/kernel-frameworks2/kernel-frameworks2.tex | 21 +++------
slides/kernel-i2c/kernel-i2c.tex | 3 ++
slides/kernel-pinmuxing/kernel-pinmuxing.tex | 52 +++++++++++++++-------
6 files changed, 48 insertions(+), 36 deletions(-)
diff --git a/slides/kernel-device-model/kernel-device-model.tex b/slides/kernel-device-model/kernel-device-model.tex
index 57466f54..cb26eea8 100644
--- a/slides/kernel-device-model/kernel-device-model.tex
+++ b/slides/kernel-device-model/kernel-device-model.tex
@@ -21,7 +21,7 @@
\begin{frame}
\frametitle{Kernel and Device Drivers}
\begin{columns}
- \column{0.5\textwidth} In Linux, a driver is always interfacing
+ \column{0.7\textwidth} In Linux, a driver is always interfacing
with:
\begin{itemize}
\item a {\bf framework} that allows the driver to expose the
@@ -31,7 +31,7 @@
\end{itemize}
This section focuses on the {\em device model}, while {\em kernel
frameworks} are covered later in this training.
- \column{0.5\textwidth}
+ \column{0.3\textwidth}
\includegraphics[height=0.8\textheight]{slides/kernel-device-model/driver-architecture.pdf}
\end{columns}
\end{frame}
diff --git a/slides/kernel-frameworks/kernel-frameworks.tex b/slides/kernel-frameworks/kernel-frameworks.tex
index ca3c336a..b398a318 100644
--- a/slides/kernel-frameworks/kernel-frameworks.tex
+++ b/slides/kernel-frameworks/kernel-frameworks.tex
@@ -3,7 +3,7 @@
\begin{frame}
\frametitle{Kernel and Device Drivers}
\begin{columns}
- \column{0.5\textwidth} In Linux, a driver is always interfacing
+ \column{0.7\textwidth} In Linux, a driver is always interfacing
with:
\begin{itemize}
\item a {\bf framework} that allows the driver to expose the
@@ -13,7 +13,7 @@
\end{itemize}
This section focuses on the {\em kernel frameworks}, while the
{\em device model} was covered earlier in this training.
- \column{0.5\textwidth}
+ \column{0.3\textwidth}
\includegraphics[height=0.8\textheight]{slides/kernel-frameworks/driver-architecture.pdf}
\end{columns}
\end{frame}
diff --git a/slides/kernel-frameworks2/kernel-frameworks2.tex b/slides/kernel-frameworks2/kernel-frameworks2.tex
index 78533024..0d461951 100644
--- a/slides/kernel-frameworks2/kernel-frameworks2.tex
+++ b/slides/kernel-frameworks2/kernel-frameworks2.tex
@@ -55,7 +55,7 @@ Many more operations exist. All of them are optional.
\item {\bf Only implement this function when you do something
special with the device at \code{open()} time.}
\item \kstruct{inode} is a structure that uniquely represents a file
- in the system (be it a regular file, a directory, a symbolic
+ in the filesystem (be it a regular file, a directory, a symbolic
link, a character or block device)
\item \kstruct{file} is a structure created every time a file is
opened. Several file structures can point to the same
@@ -78,11 +78,10 @@ Many more operations exist. All of them are optional.
\end{itemize}
\end{frame}
-\begin{frame}
- \frametitle{read()}
+\begin{frame}[fragile]
+ \frametitle{read() and write()}
\begin{itemize}
- \item \mint{c}+ssize_t foo_read(struct file *f, char __user *buf,+
- \mint{c}+size_t sz, loff_t *off)+
+ \item \mint[fontsize=\small]{c}+ssize_t foo_read(struct file *f, char __user *buf, size_t sz, loff_t *off)+
\begin{itemize}
\item Called when user space uses the \code{read()} system call on
the device.
@@ -97,14 +96,7 @@ Many more operations exist. All of them are optional.
\item On UNIX, \code{read()} operations typically block when there
isn't enough data to read from the device
\end{itemize}
- \end{itemize}
-\end{frame}
-
-\begin{frame}[fragile]
- \frametitle{write()}
- \begin{itemize}
- \item \mint{c}+ssize_t foo_write(struct file *f,+
- \mint{c}+const char __user *buf, size_t sz, loff_t *off)+
+ \item \mint[fontsize=\small]{c}+ssize_t foo_write(struct file *f, const char __user *buf, size_t sz, loff_t *off)+
\begin{itemize}
\item Called when user space uses the \code{write()} system call
on the device
@@ -189,8 +181,7 @@ Many more operations exist. All of them are optional.
\begin{frame}[fragile]
\frametitle{unlocked\_ioctl()}
\begin{itemize}
- \item \mint{c}+long unlocked_ioctl(struct file *f,+
- \mint{c}+unsigned int cmd, unsigned long arg)+
+ \item \mint[fontsize=\small]{c}+long unlocked_ioctl(struct file *f, unsigned int cmd, unsigned long arg)+
\begin{itemize}
\item Associated to the \code{ioctl()} system call.
\item Called unlocked because it didn't hold the Big Kernel Lock
diff --git a/slides/kernel-i2c/kernel-i2c.tex b/slides/kernel-i2c/kernel-i2c.tex
index 1e794999..4b1cf9ea 100644
--- a/slides/kernel-i2c/kernel-i2c.tex
+++ b/slides/kernel-i2c/kernel-i2c.tex
@@ -162,6 +162,9 @@ static void __init em7210_init_machine(void)
I2C controller node, where the \code{reg} property gives the I2C
slave address on the bus.
\end{itemize}
+ \item See the binding for the corresponding driver for a
+ specification of the expected DT properties. Example:
+ \kfile{Documentation/devicetree/bindings/i2c/i2c-omap.txt}
\end{itemize}
\end{frame}
diff --git a/slides/kernel-pinmuxing/kernel-pinmuxing.tex b/slides/kernel-pinmuxing/kernel-pinmuxing.tex
index a947015e..d116a3a5 100644
--- a/slides/kernel-pinmuxing/kernel-pinmuxing.tex
+++ b/slides/kernel-pinmuxing/kernel-pinmuxing.tex
@@ -48,29 +48,47 @@
\end{center}
\end{frame}
-\begin{frame}[fragile]{Device Tree binding for consumer devices}
+\begin{frame}[fragile]{Device Tree properties for consumer devices}
+ The devices that require certains pins to be muxed will use
+ the \code{pinctrl-<x>} and \code{pinctrl-names} Device Tree
+ properties.
\begin{itemize}
- \item The devices that require certains pins to be muxed will use
- the \code{pinctrl-<x>} and \code{pinctrl-names} Device Tree
- properties.
- \item The \code{pinctrl-0}, \code{pinctrl-1}, \code{pinctrl-<x>}
- properties link to a pin configuration for a given state of the
- device.
- \item The \code{pinctrl-names} property associates a name to each
- state. The name \code{default} is special, and is automatically
- selected by a device driver, without having to make an explicit
- {\em pinctrl} function call.
- \item In most cases, the following is sufficient:
+ \item The \code{pinctrl-0}, \code{pinctrl-1}, \code{pinctrl-<x>}
+ properties link to a pin configuration for a given state of the
+ device.
+ \item The \code{pinctrl-names} property associates a name to each
+ state. The name \code{default} is special, and is automatically
+ selected by a device driver, without having to make an explicit
+ {\em pinctrl} function call.
+ \item See \kerneldoctext{devicetree/bindings/pinctrl/pinctrl-bindings.txt}
+ for details.
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Device Tree properties for consumer devices - Examples}
+ \begin{columns}
+ \column{0.5\textwidth}
\begin{minted}[fontsize=\footnotesize]{perl}
-i2c at 11000 {
+i2c0: i2c at 11000 {
+ ...
pinctrl-0 = <&pmx_twsi0>;
pinctrl-names = "default";
...
};
\end{minted}
-\item See \kerneldoctext{devicetree/bindings/pinctrl/pinctrl-bindings.txt}
- for details.
-\end{itemize}
+ Most common case (\kfile{arch/arm/boot/dts/kirkwood.dtsi})
+ \column{0.5\textwidth}
+ \begin{minted}[fontsize=\footnotesize]{perl}
+i2c0: i2c at f8014000 {
+ ...
+ pinctrl-names = "default", "gpio";
+ pinctrl-0 = <&pinctrl_i2c0>;
+ pinctrl-1 = <&pinctrl_i2c0_gpio>;
+ ...
+};
+\end{minted}
+ Case with multiple pin states (\kfile{arch/arm/boot/dts/sama5d4.dtsi})
+ \end{columns}
\end{frame}
\begin{frame}{Defining pinctrl configurations}
@@ -143,7 +161,7 @@ i2c at 11000 {
\end{columns}
\end{frame}
-\begin{frame}[fragile]{Example on Allwinner SoC}
+\begin{frame}[fragile]{Example on the Allwinner A20 SoC}
\begin{center}
\includegraphics[height=0.8\textheight]{slides/kernel-pinmuxing/allwinner-example.pdf}
\end{center}
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