net: stmmac: dwmac-loongson: Add Loongson GNET support

Aside with the Loongson GMAC controllers which can be normally found
on the LS2K1000 SoC and LS7A1000 chipset, Loongson released a new
version of the network controllers called Loongson GNET. It has
been synthesized into the new generation LS2K2000 SoC and LS7A2000
chipset with the next DW GMAC features enabled:

  DW GMAC IP-core: v3.73a
  Speeds: 10/100/1000Mbps
  Duplex: Full (both versions), Half (LS2K2000 SoC only)
  DMA-descriptors type: enhanced
  L3/L4 filters availability: Y
  VLAN hash table filter: Y
  PHY-interface: GMII (PHY is integrated into the chips)
  Remote Wake-up support: Y
  Mac Management Counters (MMC): Y
  Number of additional MAC addresses: 5
  MAC Hash-based filter: Y
  Hash Table Size: 256
  AV feature: Y (LS2K2000 SoC only)
  DMA channels: 8 (LS2K2000 SoC), 1 (LS7A2000 chipset)

The integrated PHY has a weird problem with switching from the low
speeds to 1000Mbps mode. The speedup procedure requires the PHY-link
re-negotiation. Besides the LS2K2000 GNET controller the next
peculiarities:
1. Split up Tx and Rx DMA IRQ status/mask bits:
       Name              Tx          Rx
  DMA_INTR_ENA_NIE = 0x00040000 | 0x00020000;
  DMA_INTR_ENA_AIE = 0x00010000 | 0x00008000;
  DMA_STATUS_NIS   = 0x00040000 | 0x00020000;
  DMA_STATUS_AIS   = 0x00010000 | 0x00008000;
  DMA_STATUS_FBI   = 0x00002000 | 0x00001000;
2. Custom Synopsys ID hardwired into the GMAC_VERSION.SNPSVER field.
It's 0x10 while it should have been 0x37 in accordance with the actual
DW GMAC IP-core version.

Thus in order to have the Loongson GNET controllers supported let's
modify the Loongson DWMAC driver in accordance with all the
peculiarities described above:

1. Create the Loongson GNET-specific
   stmmac_dma_ops::dma_interrupt()
   stmmac_dma_ops::init_chan()
   callbacks due to the non-standard DMA IRQ CSR flags layout.
2. Create the Loongson GNET-specific platform setup() method which
gets to initialize the DMA-ops with the dwmac1000_dma_ops instance
and overrides the callbacks described in 1, and overrides the custom
Synopsys ID with the real one in order to have the rest of the
HW-specific callbacks correctly detected by the driver core.
3. Make sure the Loongson GNET-specific platform setup() method
enables the duplex modes supported by the controller.
4. Provide the plat_stmmacenet_data::fix_mac_speed() callback which
will restart the link Auto-negotiation in case of the speed change.

Signed-off-by: Feiyang Chen <[email protected]>
Signed-off-by: Yinggang Gu <[email protected]>
Signed-off-by: Yanteng Si <[email protected]>

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

@@ -29,6 +29,7 @@
 /* Synopsys Core versions */
 #define	DWMAC_CORE_3_40		0x34
 #define	DWMAC_CORE_3_50		0x35
+#define	DWMAC_CORE_3_70		0x37
 #define	DWMAC_CORE_4_00		0x40
 #define DWMAC_CORE_4_10		0x41
 #define DWMAC_CORE_5_00		0x50