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-rw-r--r--drivers/firewire/core-card.c28
-rw-r--r--drivers/firewire/core-cdev.c6
2 files changed, 32 insertions, 2 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);
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 9f89c17730b1..8e9670036e5c 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -1216,7 +1216,9 @@ static int ioctl_get_cycle_timer2(struct client *client, union ioctl_arg *arg)
local_irq_disable();
- cycle_time = card->driver->read_csr(card, CSR_CYCLE_TIME);
+ ret = fw_card_read_cycle_time(card, &cycle_time);
+ if (ret < 0)
+ goto end;
switch (a->clk_id) {
case CLOCK_REALTIME: ktime_get_real_ts64(&ts); break;
@@ -1225,7 +1227,7 @@ static int ioctl_get_cycle_timer2(struct client *client, union ioctl_arg *arg)
default:
ret = -EINVAL;
}
-
+end:
local_irq_enable();
a->tv_sec = ts.tv_sec;