This patch adds support for interrupts to the virtio-gpio specification. This uses the feature bit 0 for the same.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- conformance.tex | 2 + virtio-gpio.tex | 241 +++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 242 insertions(+), 1 deletion(-)
diff --git a/conformance.tex b/conformance.tex index c52f1a40be2d..64bcc12d1199 100644 --- a/conformance.tex +++ b/conformance.tex @@ -310,6 +310,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
\begin{itemize} \item \ref{drivernormative:Device Types / GPIO Device / requestq Operation} +\item \ref{drivernormative:Device Types / GPIO Device / eventq Operation} \end{itemize}
\conformance{\section}{Device Conformance}\label{sec:Conformance / Device Conformance} @@ -568,6 +569,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
\begin{itemize} \item \ref{devicenormative:Device Types / GPIO Device / requestq Operation} +\item \ref{devicenormative:Device Types / GPIO Device / eventq Operation} \end{itemize}
\conformance{\section}{Legacy Interface: Transitional Device and Transitional Driver Conformance}\label{sec:Conformance / Legacy Interface: Transitional Device and Transitional Driver Conformance} diff --git a/virtio-gpio.tex b/virtio-gpio.tex index fa48780a29db..f432a3f3ad0d 100644 --- a/virtio-gpio.tex +++ b/virtio-gpio.tex @@ -11,11 +11,17 @@ \subsection{Virtqueues}\label{sec:Device Types / GPIO Device / Virtqueues}
\begin{description} \item[0] requestq +\item[1] eventq \end{description}
+The \field{eventq} virtqueue is available only if the \field{VIRTIO_GPIO_F_IRQ} +feature is enabled by the device. + \subsection{Feature bits}\label{sec:Device Types / GPIO Device / Feature bits}
-None currently defined. +\begin{description} +\item[VIRTIO_GPIO_F_IRQ (0)] The device supports interrupts on GPIO lines. +\end{description}
\subsection{Device configuration layout}\label{sec:Device Types / GPIO Device / Device configuration layout}
@@ -46,6 +52,15 @@ \subsection{Device Initialization}\label{sec:Device Types / GPIO Device / Device
\begin{itemize} \item The driver MUST configure and initialize the \field{requestq} virtqueue. + +\item The driver MUST check the presence of \field{VIRTIO_GPIO_F_IRQ} feature + before initiating any IRQ messages. + +\item The driver MUST configure and initialize the \field{eventq} virtqueue if + the \field{VIRTIO_GPIO_F_IRQ} feature is enabled by the device. + +\item The device MUST have interrupts on all the GPIO lines masked, if the + \field{VIRTIO_GPIO_F_IRQ} feature is supported. \end{itemize}
\subsection{Device Operation: requestq}\label{sec:Device Types / GPIO Device / requestq Operation} @@ -111,6 +126,19 @@ \subsection{Device Operation: requestq}\label{sec:Device Types / GPIO Device / r #define VIRTIO_GPIO_MSG_SET_DIRECTION_OUT 0x0006 #define VIRTIO_GPIO_MSG_GET_VALUE 0x0007 #define VIRTIO_GPIO_MSG_SET_VALUE 0x0008 +#define VIRTIO_GPIO_MSG_IRQ_TYPE 0x0009 +#define VIRTIO_GPIO_MSG_IRQ_MASK 0x000a +#define VIRTIO_GPIO_MSG_IRQ_UNMASK 0x000b +\end{lstlisting} + +\begin{lstlisting} +/* GPIO interrupt types */ +#define VIRTIO_GPIO_IRQ_TYPE_NONE 0x00 +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING 0x01 +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING 0x02 +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH 0x03 +#define VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH 0x04 +#define VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW 0x08 \end{lstlisting}
\subsubsection{requestq Operation: Get Names}\label{sec:Device Types / GPIO Device / requestq Operation / Get Names} @@ -294,6 +322,79 @@ \subsubsection{requestq Operation: Set Value}\label{sec:Device Types / GPIO Devi \hline \end{tabularx}
+\subsubsection{requestq Operation: IRQ Type}\label{sec:Device Types / GPIO Device / requestq Operation / IRQ Type} + +The driver initiates this message to request the device to set the IRQ trigger +type, to one of the \field{VIRTIO_GPIO_IRQ_TYPE_*} values, for a line configured +for input. + +This request is only allowed if the \field{VIRTIO_GPIO_F_IRQ} feature is +enabled by the device. + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Request} & \field{type} & \field{gpio} & \field{value} \ +\hline +& \field{VIRTIO_GPIO_MSG_IRQ_TYPE} & line number & one of \field{VIRTIO_GPIO_IRQ_TYPE_*} \ +\hline +\end{tabularx} + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Response} & \field{status} & \field{value[N]} & \field{Where N is} \ +\hline +& \field{VIRTIO_GPIO_STATUS_*} & 0 & 1 \ +\hline +\end{tabularx} + +\subsubsection{requestq Operation: IRQ Mask}\label{sec:Device Types / GPIO Device / requestq Operation / IRQ Mask} + +The driver initiates this message to request the device to mask IRQ on a GPIO +line configured for input. + +This request is only allowed if the \field{VIRTIO_GPIO_F_IRQ} feature is +enabled by the device. + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Request} & \field{type} & \field{gpio} & \field{value} \ +\hline +& \field{VIRTIO_GPIO_MSG_IRQ_MASK} & line number & 0 \ +\hline +\end{tabularx} + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Response} & \field{status} & \field{value[N]} & \field{Where N is} \ +\hline +& \field{VIRTIO_GPIO_STATUS_*} & 0 & 1 \ +\hline +\end{tabularx} + +\subsubsection{requestq Operation: IRQ Unmask}\label{sec:Device Types / GPIO Device / requestq Operation / IRQ Unmask} + +The driver initiates this message to request the device to unmask IRQ on a GPIO +line configured for input. + +This request is only allowed if the \field{VIRTIO_GPIO_F_IRQ} feature is +enabled by the device. + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Request} & \field{type} & \field{gpio} & \field{value} \ +\hline +& \field{VIRTIO_GPIO_MSG_IRQ_UNMASK} & line number & 0 \ +\hline +\end{tabularx} + +\begin{tabularx}{\textwidth}{ |l||X|X|X| } +\hline +\textbf{Response} & \field{status} & \field{value[N]} & \field{Where N is} \ +\hline +& \field{VIRTIO_GPIO_STATUS_*} & 0 & 1 \ +\hline +\end{tabularx} + \subsubsection{requestq Operation: Message Flow}\label{sec:Device Types / GPIO Device / requestq Operation / Message Flow}
\begin{itemize} @@ -343,6 +444,17 @@ \subsubsection{requestq Operation: Message Flow}\label{sec:Device Types / GPIO D \item The driver MUST NOT send another message, of any type, for a GPIO line before receiving a response from the device for the previously sent message for the same GPIO line. + +\item The driver MUST NOT send IRQ messages for a GPIO line configured for + output. + +\item The driver MUST NOT initiate IRQ messages if the \field{VIRTIO_GPIO_F_IRQ} + feature is not enabled by the device. + +\item If the driver has sent the \field{VIRTIO_GPIO_MSG_IRQ_UNMASK} message + earlier for a GPIO line, then it MUST send the + \field{VIRTIO_GPIO_MSG_IRQ_MASK} message over the \field{requestq} + virtqueue, if it no longer wants to receive interrupts from the device. \end{itemize}
\devicenormative{\subsubsection}{requestq Operation}{Device Types / GPIO Device / requestq Operation} @@ -367,3 +479,130 @@ \subsubsection{requestq Operation: Message Flow}\label{sec:Device Types / GPIO D \item The device MAY process messages out of order and in parallel and MAY send message's response to the driver out of order. \end{itemize} + +\subsection{Device Operation: eventq}\label{sec:Device Types / GPIO Device / eventq Operation} + +The \field{eventq} virtqueue is used for sending interrupt events from the +device to the driver. The driver queues a separate pair of buffers, +interrupt-request (filled by driver) and interrupt-response (to be filled by +device later), to the \field{eventq} virtqueue for each GPIO line. The device, +on sensing an interrupt, returns the pair of buffers of the respective GPIO line +for which the interrupt is sensed. + +\begin{lstlisting} +struct virtio_gpio_irq_request { + le16 gpio; +}; +\end{lstlisting} + +This structure is filled by the driver and read by the device. + +\begin{description} +\item[\field{gpio}] is the GPIO line number, i.e. 0 <= \field{gpio} < + \field{ngpio}. +\end{description} + +\begin{lstlisting} +struct virtio_gpio_irq_response { + u8 status; +}; + +/* Possible values of the interrupt status field */ +#define VIRTIO_GPIO_IRQ_INVALID 0x0 +#define VIRTIO_GPIO_IRQ_VALID 0x1 +\end{lstlisting} + +This structure is filled by the device and read by the driver. + +\begin{description} +\item[\field{status}] of the interrupt event, \field{VIRTIO_GPIO_IRQ_VALID} on + valid interrupt and \field{VIRTIO_GPIO_IRQ_INVALID} otherwise on returning + the buffer back to the driver without an interrupt. +\end{description} + +\subsubsection{eventq Operation: Message Flow}\label{sec:Device Types / GPIO Device / eventq Operation / Message Flow} + +\begin{itemize} +\item The driver is requested by a user to enable interrupt for a GPIO and + configure it to a particular type. + +\item The driver sends the \field{VIRTIO_GPIO_MSG_IRQ_TYPE} message over the + \field{requestq} virtqueue and the device configures the GPIO line for the + same and responds. + +\item The driver queues a pair of buffers, interrupt-request and + interrupt-response, to the \field{eventq} virtqueue for the GPIO line. + +\item The driver notifies the device of the presence of new buffers on the + \field{eventq} virtqueue. + +\item The driver sends the \field{VIRTIO_GPIO_MSG_IRQ_UNMASK} message over the + \field{requestq} virtqueue and the device configures the GPIO line for the + same and responds. + +\item The interrupt is fully configured at this point. + +\item The device, on sensing an interrupt on a GPIO line, finds the matching + buffers (based on GPIO line number) from the \field{eventq} virtqueue and + fills its \field{struct virtio_gpio_irq_response} buffer's \field{status} + with \field{VIRTIO_GPIO_IRQ_VALID} and returns the pair of buffers to the + device. + +\item The device notifies the driver of the presence of new buffers on the + \field{eventq} virtqueue. + +\item If the GPIO line is configured for Level interrupts, the device MUST + ignore any further interrupts for the line, until the time the buffers are + made available again by the driver. + +\item If the GPIO line is configured for Edge interrupts, the device MUST latch + the latest interrupt received for the line, until the time the buffers are + made available again by the driver. At that point, the device can again + return the buffers for the line if an interrupt was received while the + device was waiting for the buffers to be made available by the driver. + +\item The driver on receiving the notification from the device, processes the + interrupt. The driver may try to mask/unmask the interrupts for the GPIO + line over the \field{requestq} virtqueue. + +\item The driver may again queue, same or new, pair of buffers for that GPIO + line and notify the device. + +\item The driver may send the \field{VIRTIO_GPIO_MSG_IRQ_MASK} message over the + \field{requestq} virtqueue, once it no longer wants to receive the + interrupts for a GPIO line. + +\item The device must return the unused pair of buffers for that GPIO line, over + the \field{eventq} virtqueue, by setting the \field{status} field with + \field{VIRTIO_GPIO_IRQ_INVALID}. + +\item The driver can then free the associated buffer and remove it from the + \field{eventq} virtqueue. +\end{itemize} + +\drivernormative{\subsubsection}{eventq Operation}{Device Types / GPIO Device / eventq Operation} + +\begin{itemize} +\item The driver MUST queue a separate pair of buffers, interrupt-request and + interrupt-response, to the \field{eventq} virtqueue for each GPIO line for + which it is expecting an interrupt from the device. + +\item The driver MUST not queue a pair of buffers for a GPIO line which it is + not going to use as interrupt source, otherwise the buffer may never be + freed by the device (as no unmask request will follow from the driver). + +\item The driver MUST NOT add multiple pairs of buffers for the same GPIO line + on the \field{eventq} virtqueue. And so there can only be one interrupt + event for each GPIO line at any point of time. + +\item The pair of buffers for any GPIO line can either be owned by the device or + the driver at any particular point of time, but not both. +\end{itemize} + +\devicenormative{\subsubsection}{eventq Operation}{Device Types / GPIO Device / eventq Operation} + +\begin{itemize} +\item The device can send an interrupt event for a GPIO line to the driver, only + if a buffer for that GPIO line is provided by the driver in the first place + on the \field{eventq} virtqueue. +\end{itemize}