stmmac: add the support for PTP hw clock driver

This patch implements PHC (ptp hardware clock) driver for stmmac
driver to support 1588 PTP.

V2: added support for FINE method, reduced loop delay and review spinlock.

Signed-off-by: Rayagond Kokatanur <rayagond@vayavyalabs.com>
Hacked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/common.h

@@ -411,6 +411,9 @@ struct stmmac_hwtimestamp {
 	void (*config_sub_second_increment) (void __iomem *ioaddr);
 	int (*init_systime) (void __iomem *ioaddr, u32 sec, u32 nsec);
 	int (*config_addend)(void __iomem *ioaddr, u32 addend);
+	int (*adjust_systime)(void __iomem *ioaddr, u32 sec, u32 nsec,
+			      int add_sub);
+	u64 (*get_systime)(void __iomem *ioaddr);
 };
 
 struct mac_link {