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lm4f: Add functions for controlling USB interrupts

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Add functions to enable and disable USB interrupts, and document how to
use these functions to run usbd_poll() from the usb ISR.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
This commit is contained in:
Alexandru Gagniuc
2013-05-15 18:46:05 -05:00
parent ad048f7d5a
commit 9d46103ced
2 changed files with 128 additions and 0 deletions
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93
lib/lm4f/usb_lm4f.c
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@@ -40,6 +40,47 @@
* usbd_dev = usbd_init(&lm4f_usb_driver, ...);
* @endcode
*
* <b>Polling or interrupt-driven? </b>
*
* The LM4F USB driver will work fine regardless of whether it is called from an
* interrupt service routine, or from the main program loop.
*
* Polling USB from the main loop requires calling @ref usbd_poll() from the
* main program loop.
* For example:
* @code{.c}
* // Main program loop
* while(1) {
* usbd_poll(usb_dev);
* do_other_stuff();
* ...
* @endcode
*
* Running @ref usbd_poll() from an interrupt has the advantage that it is only
* called when needed, saving CPU cycles for the main program.
*
* RESET, DISCON, RESUME, and SUSPEND interrupts must be enabled, along with the
* interrupts for any endpoint that is used. The EP0_TX interrupt must be
* enabled for the control endpoint to function correctly.
* For example, if EP1IN and EP2OUT are used, then the EP0_TX, EP1_TX, and
* EP2_RX interrupts should be enabled:
* @code{.c}
* // Enable USB interrupts for EP0, EP1IN, and EP2OUT
* ints = USB_INT_RESET | USB_INT_DISCON | USB_INT_RESUME |
* USB_INT_SUSPEND;
* usb_enable_interrupts(ints, USB_EP2_INT, USB_EP0_INT | USB_EP1_INT);
* // Route the interrupts through the NVIC
* nvic_enable_irq(NVIC_USB0_IRQ);
* @endcode
*
* The USB ISR only has to call @ref usbd_poll().
*
* @code{.c}
* void usb0_isr(void)
* {
* usbd_poll(usb_dev);
* }
* @endcode
* @{
*/
@@ -70,6 +111,58 @@
const struct _usbd_driver lm4f_usb_driver;
/**
* \brief Enable Specific USB Interrupts
*
* Enable any combination of interrupts. Interrupts may be OR'ed together to
* enable them with one call. For example, to enable both the RESUME and RESET
* interrupts, pass (USB_INT_RESUME | USB_INT_RESET)
*
* Note that the NVIC must be enabled and properly configured for the interrupt
* to be routed to the CPU.
*
* @param[in] ints Interrupts which to enable. Any combination of interrupts may
* be specified by OR'ing then together
* @param[in] rx_ints Endpoints for which to generate an interrupt when a packet
* packet is received.
* @param[in] tx_ints Endpoints for which to generate an interrupt when a packet
* packet is finished transmitting.
*/
void usb_enable_interrupts(enum usb_interrupt ints,
enum usb_ep_interrupt rx_ints,
enum usb_ep_interrupt tx_ints)
{
USB_IE |= ints;
USB_RXIE |= rx_ints;
USB_TXIE |= tx_ints;
}
/**
* \brief Disable Specific USB Interrupts
*
* Disable any combination of interrupts. Interrupts may be OR'ed together to
* enable them with one call. For example, to disable both the RESUME and RESET
* interrupts, pass (USB_INT_RESUME | USB_INT_RESET)
*
* Note that the NVIC must be enabled and properly configured for the interrupt
* to be routed to the CPU.
*
* @param[in] ints Interrupts which to disable. Any combination of interrupts
* may be specified by OR'ing then together
* @param[in] rx_ints Endpoints for which to stop generating an interrupt when a
* packet packet is received.
* @param[in] tx_ints Endpoints for which to stop generating an interrupt when a
* packet packet is finished transmitting.
*/
void usb_disable_interrupts(enum usb_interrupt ints,
enum usb_ep_interrupt rx_ints,
enum usb_ep_interrupt tx_ints)
{
USB_IE &= ~ints;
USB_RXIE &= ~rx_ints;
USB_TXIE &= ~tx_ints;
}
/**
* @cond private
*/