drivers: net: cpsw: ale: add broadcast/multicast rate limit support
The CPSW ALE supports feature to rate limit number ingress broadcast(BC)/multicast(MC) packets per/sec which main purpose is BC/MC storm prevention. The ALE BC/MC packet rate limit configuration consist of two parts: - global ALE_CONTROL.ENABLE_RATE_LIMIT bit 0 which enables rate limiting globally ALE_PRESCALE.PRESCALE specifies rate limiting interval - per-port ALE_PORTCTLx.BCASTMCAST/_LIMIT specifies number of BC/MC packets allowed per rate limiting interval. When port.BCASTMCAST/_LIMIT is 0 rate limiting is disabled for Port. When BC/MC packet rate limiting is enabled the number of allowed packets per/sec is defined as: number_of_packets/sec = (Fclk / ALE_PRESCALE) * port.BCASTMCAST/_LIMIT Hence, the ALE_PRESCALE configuration is common for all ports the 1ms interval is selected and configured during ALE initialization while port.BCAST/MCAST_LIMIT are configured per-port. This allows to achieve: - min number_of_packets = 1000 when port.BCAST/MCAST_LIMIT = 1 - max number_of_packets = 1000 * 255 = 255000 when port.BCAST/MCAST_LIMIT = 0xFF The ALE_CONTROL.ENABLE_RATE_LIMIT can also be enabled once during ALE initialization as rate limiting enabled by non zero port.BCASTMCAST/_LIMIT values. This patch implements above logic in ALE and adds new ALE APIs cpsw_ale_rx_ratelimit_bc(); cpsw_ale_rx_ratelimit_mc(); Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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