net: cadence: macb: enable EEE for Raspberry Pi RP1

commit 92ba330 upstream

Set MACB_CAPS_EEE for the Raspberry Pi 5 RP1 southbridge
(Cadence GEM_GXL rev 0x00070109 paired with BCM54213PE PHY).

EEE has been verified on RP1 hardware: the LPI counter registers
at 0x270-0x27c return valid data, the TXLPIEN bit in NCR (bit 19)
controls LPI transmission correctly, and ethtool --show-eee reports
the negotiated state after link-up.

Other GEM variants that share the same LPI register layout (SAMA5D2,
SAME70, PIC32CZ) can be enabled by adding MACB_CAPS_EEE to their
respective config entries once tested.

Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

Author: nbuchwitz

drivers/net/ethernet/cadence/macb_main.c

@@ -5626,7 +5626,8 @@ static const struct macb_config versal_config = {
 static const struct macb_config raspberrypi_rp1_config = {
 	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE | MACB_CAPS_CLK_HW_CHG |
 		MACB_CAPS_JUMBO |
-		MACB_CAPS_GEM_HAS_PTP,
+		MACB_CAPS_GEM_HAS_PTP |
+		MACB_CAPS_EEE,
 	.dma_burst_length = 16,
 	.clk_init = macb_clk_init,
 	.init = macb_init,