net: ll_temac: Prepare indirect register access for multicast support

With .ndo_set_rx_mode/temac_set_multicast_list() being called in atomic
context (holding addr_list_lock), and temac_set_multicast_list() needing
to access temac indirect registers, the mutex used to synchronize indirect
register is a no-no.

Replace it with a spinlock, and avoid sleeping in
temac_indirect_busywait().

To avoid excessive holding of the lock, which is now a spinlock, the
temac_device_reset() function is changed to only hold the lock for short
periods.  With timeouts, it could be holding the spinlock for more than
2 seconds.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/platform_data/xilinx-ll-temac.h

@@ -4,6 +4,7 @@
 
 #include <linux/if_ether.h>
 #include <linux/phy.h>
+#include <linux/spinlock.h>
 
 struct ll_temac_platform_data {
 	bool txcsum;		/* Enable/disable TX checksum */
@@ -21,7 +22,7 @@ struct ll_temac_platform_data {
 	 * TEMAC IP block, the same mutex should be passed here, as
 	 * they share the same DCR bus bridge.
 	 */
-	struct mutex *indirect_mutex;
+	spinlock_t *indirect_lock;
 	/* DMA channel control setup */
 	u8 tx_irq_timeout;	/* TX Interrupt Delay Time-out */
 	u8 tx_irq_count;	/* TX Interrupt Coalescing Threshold Count */