diff options
Diffstat (limited to 'drivers/firewire/core-card.c')
| -rw-r--r-- | drivers/firewire/core-card.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c index d994da6cf465..cd09de61bc4f 100644 --- a/drivers/firewire/core-card.c +++ b/drivers/firewire/core-card.c @@ -702,3 +702,31 @@ void fw_core_remove_card(struct fw_card *card) WARN_ON(!list_empty(&card->transaction_list)); } EXPORT_SYMBOL(fw_core_remove_card); + +/** + * fw_card_read_cycle_time: read from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region + * for controller card. + * @card: The instance of card for 1394 OHCI controller. + * @cycle_time: The mutual reference to value of cycle time for the read operation. + * + * Read value from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region for the given + * controller card. This function accesses the region without any lock primitives or IRQ mask. + * When returning successfully, the content of @value argument has value aligned to host endianness, + * formetted by CYCLE_TIME CSR Register of IEEE 1394 std. + * + * Context: Any context. + * Return: + * * 0 - Read successfully. + * * -ENODEV - The controller is unavailable due to being removed or unbound. + */ +int fw_card_read_cycle_time(struct fw_card *card, u32 *cycle_time) +{ + if (card->driver->read_csr == dummy_read_csr) + return -ENODEV; + + // It's possible to switch to dummy driver between the above and the below. This is the best + // effort to return -ENODEV. + *cycle_time = card->driver->read_csr(card, CSR_CYCLE_TIME); + return 0; +} +EXPORT_SYMBOL_GPL(fw_card_read_cycle_time); |