mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

qdev: Document GPIO related functions

Browse Source 
Add documentation comments for the various qdev functions
related to creating and connecting GPIO lines.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200711142425.16283-4-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2020-07-11 15:24:25 +01:00
parent 46ea1be1ee
commit cd07d7f9f5
1 changed files with 189 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

191
include/hw/qdev-core.h
View File

@ -424,13 +424,132 @@ void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
void qdev_machine_creation_done(void);
bool qdev_machine_modified(void);
/**
* qdev_get_gpio_in: Get one of a device's anonymous input GPIO lines
* @dev: Device whose GPIO we want
* @n: Number of the anonymous GPIO line (which must be in range)
*
* Returns the qemu_irq corresponding to an anonymous input GPIO line
* (which the device has set up with qdev_init_gpio_in()). The index
* @n of the GPIO line must be valid (i.e. be at least 0 and less than
* the total number of anonymous input GPIOs the device has); this
* function will assert() if passed an invalid index.
*
* This function is intended to be used by board code or SoC "container"
* device models to wire up the GPIO lines; usually the return value
* will be passed to qdev_connect_gpio_out() or a similar function to
* connect another device's output GPIO line to this input.
*
* For named input GPIO lines, use qdev_get_gpio_in_named().
*/
qemu_irq qdev_get_gpio_in(DeviceState *dev, int n);
/**
* qdev_get_gpio_in_named: Get one of a device's named input GPIO lines
* @dev: Device whose GPIO we want
* @name: Name of the input GPIO array
* @n: Number of the GPIO line in that array (which must be in range)
*
* Returns the qemu_irq corresponding to a named input GPIO line
* (which the device has set up with qdev_init_gpio_in_named()).
* The @name string must correspond to an input GPIO array which exists on
* the device, and the index @n of the GPIO line must be valid (i.e.
* be at least 0 and less than the total number of input GPIOs in that
* array); this function will assert() if passed an invalid name or index.
*
* For anonymous input GPIO lines, use qdev_get_gpio_in().
*/
qemu_irq qdev_get_gpio_in_named(DeviceState *dev, const char *name, int n);
/**
* qdev_connect_gpio_out: Connect one of a device's anonymous output GPIO lines
* @dev: Device whose GPIO to connect
* @n: Number of the anonymous output GPIO line (which must be in range)
* @pin: qemu_irq to connect the output line to
*
* This function connects an anonymous output GPIO line on a device
* up to an arbitrary qemu_irq, so that when the device asserts that
* output GPIO line, the qemu_irq's callback is invoked.
* The index @n of the GPIO line must be valid (i.e. be at least 0 and
* less than the total number of anonymous output GPIOs the device has
* created with qdev_init_gpio_out()); otherwise this function will assert().
*
* Outbound GPIO lines can be connected to any qemu_irq, but the common
* case is connecting them to another device's inbound GPIO line, using
* the qemu_irq returned by qdev_get_gpio_in() or qdev_get_gpio_in_named().
*
* It is not valid to try to connect one outbound GPIO to multiple
* qemu_irqs at once, or to connect multiple outbound GPIOs to the
* same qemu_irq. (Warning: there is no assertion or other guard to
* catch this error: the model will just not do the right thing.)
* Instead, for fan-out you can use the TYPE_IRQ_SPLIT device: connect
* a device's outbound GPIO to the splitter's input, and connect each
* of the splitter's outputs to a different device. For fan-in you
* can use the TYPE_OR_IRQ device, which is a model of a logical OR
* gate with multiple inputs and one output.
*
* For named output GPIO lines, use qdev_connect_gpio_out_named().
*/
void qdev_connect_gpio_out(DeviceState *dev, int n, qemu_irq pin);
/**
* qdev_connect_gpio_out: Connect one of a device's anonymous output GPIO lines
* @dev: Device whose GPIO to connect
* @name: Name of the output GPIO array
* @n: Number of the anonymous output GPIO line (which must be in range)
* @pin: qemu_irq to connect the output line to
*
* This function connects an anonymous output GPIO line on a device
* up to an arbitrary qemu_irq, so that when the device asserts that
* output GPIO line, the qemu_irq's callback is invoked.
* The @name string must correspond to an output GPIO array which exists on
* the device, and the index @n of the GPIO line must be valid (i.e.
* be at least 0 and less than the total number of input GPIOs in that
* array); this function will assert() if passed an invalid name or index.
*
* Outbound GPIO lines can be connected to any qemu_irq, but the common
* case is connecting them to another device's inbound GPIO line, using
* the qemu_irq returned by qdev_get_gpio_in() or qdev_get_gpio_in_named().
*
* It is not valid to try to connect one outbound GPIO to multiple
* qemu_irqs at once, or to connect multiple outbound GPIOs to the
* same qemu_irq; see qdev_connect_gpio_out() for details.
*
* For named output GPIO lines, use qdev_connect_gpio_out_named().
*/
void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
qemu_irq pin);
/**
* qdev_get_gpio_out_connector: Get the qemu_irq connected to an output GPIO
* @dev: Device whose output GPIO we are interested in
* @name: Name of the output GPIO array
* @n: Number of the output GPIO line within that array
*
* Returns whatever qemu_irq is currently connected to the specified
* output GPIO line of @dev. This will be NULL if the output GPIO line
* has never been wired up to the anything. Note that the qemu_irq
* returned does not belong to @dev -- it will be the input GPIO or
* IRQ of whichever device the board code has connected up to @dev's
* output GPIO.
*
* You probably don't need to use this function -- it is used only
* by the platform-bus subsystem.
*/
qemu_irq qdev_get_gpio_out_connector(DeviceState *dev, const char *name, int n);
/**
* qdev_intercept_gpio_out: Intercept an existing GPIO connection
* @dev: Device to intercept the outbound GPIO line from
* @icpt: New qemu_irq to connect instead
* @name: Name of the output GPIO array
* @n: Number of the GPIO line in the array
*
* This function is provided only for use by the qtest testing framework
* and is not suitable for use in non-testing parts of QEMU.
*
* This function breaks an existing connection of an outbound GPIO
* line from @dev, and replaces it with the new qemu_irq @icpt, as if
* ``qdev_connect_gpio_out_named(dev, icpt, name, n)`` had been called.
* The previously connected qemu_irq is returned, so it can be restored
* by a second call to qdev_intercept_gpio_out() if desired.
*/
qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
const char *name, int n);
@ -438,10 +557,59 @@ BusState *qdev_get_child_bus(DeviceState *dev, const char *name);
/*** Device API. ***/
/* Register device properties. */
/* GPIO inputs also double as IRQ sinks. */
/**
* qdev_init_gpio_in: create an array of anonymous input GPIO lines
* @dev: Device to create input GPIOs for
* @handler: Function to call when GPIO line value is set
* @n: Number of GPIO lines to create
*
* Devices should use functions in the qdev_init_gpio_in* family in
* their instance_init or realize methods to create any input GPIO
* lines they need. There is no functional difference between
* anonymous and named GPIO lines. Stylistically, named GPIOs are
* preferable (easier to understand at callsites) unless a device
* has exactly one uniform kind of GPIO input whose purpose is obvious.
* Note that input GPIO lines can serve as 'sinks' for IRQ lines.
*
* See qdev_get_gpio_in() for how code that uses such a device can get
* hold of an input GPIO line to manipulate it.
*/
void qdev_init_gpio_in(DeviceState *dev, qemu_irq_handler handler, int n);
/**
* qdev_init_gpio_out: create an array of anonymous output GPIO lines
* @dev: Device to create output GPIOs for
* @pins: Pointer to qemu_irq or qemu_irq array for the GPIO lines
* @n: Number of GPIO lines to create
*
* Devices should use functions in the qdev_init_gpio_out* family
* in their instance_init or realize methods to create any output
* GPIO lines they need. There is no functional difference between
* anonymous and named GPIO lines. Stylistically, named GPIOs are
* preferable (easier to understand at callsites) unless a device
* has exactly one uniform kind of GPIO output whose purpose is obvious.
*
* The @pins argument should be a pointer to either a "qemu_irq"
* (if @n == 1) or a "qemu_irq []" array (if @n > 1) in the device's
* state structure. The device implementation can then raise and
* lower the GPIO line by calling qemu_set_irq(). (If anything is
* connected to the other end of the GPIO this will cause the handler
* function for that input GPIO to be called.)
*
* See qdev_connect_gpio_out() for how code that uses such a device
* can connect to one of its output GPIO lines.
*/
void qdev_init_gpio_out(DeviceState *dev, qemu_irq *pins, int n);
/**
* qdev_init_gpio_out: create an array of named output GPIO lines
* @dev: Device to create output GPIOs for
* @pins: Pointer to qemu_irq or qemu_irq array for the GPIO lines
* @name: Name to give this array of GPIO lines
* @n: Number of GPIO lines to create
*
* Like qdev_init_gpio_out(), but creates an array of GPIO output lines
* with a name. Code using the device can then connect these GPIO lines
* using qdev_connect_gpio_out_named().
*/
void qdev_init_gpio_out_named(DeviceState *dev, qemu_irq *pins,
const char *name, int n);
/**
@ -473,6 +641,25 @@ static inline void qdev_init_gpio_in_named(DeviceState *dev,
qdev_init_gpio_in_named_with_opaque(dev, handler, dev, name, n);
}
/**
* qdev_pass_gpios: create GPIO lines on container which pass through to device
* @dev: Device which has GPIO lines
* @container: Container device which needs to expose them
* @name: Name of GPIO array to pass through (NULL for the anonymous GPIO array)
*
* In QEMU, complicated devices like SoCs are often modelled with a
* "container" QOM device which itself contains other QOM devices and
* which wires them up appropriately. This function allows the container
* to create GPIO arrays on itself which simply pass through to a GPIO
* array of one of its internal devices.
*
* If @dev has both input and output GPIOs named @name then both will
* be passed through. It is not possible to pass a subset of the array
* with this function.
*
* To users of the container device, the GPIO array created on @container
* behaves exactly like any other.
*/
void qdev_pass_gpios(DeviceState *dev, DeviceState *container,
const char *name);