Re: [PATCH 11/12] net: macb: add SiFive support

The Ethernet controller on the SiFive SoCs needs some special TX clock
setup. Port the relevant Linux v5.12 bits to enable it.

Tested on qemu-system-riscv64 -M sifive_u with dhcp.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/net/macb.c | 113 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)

diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index 14a0b45322bf..9c4fdbd5bc4f 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c

@@ -52,6 +52,17 @@
 #define TX_RING_BYTES		(sizeof(struct macb_dma_desc) * TX_RING_SIZE)
 #define GEM_Q1_DESC_BYTES	(sizeof(struct macb_dma_desc) * GEM_Q1_DESCS)
 
+/* This structure is only used for MACB on SiFive FU540 devices */
+struct sifive_fu540_macb_mgmt {
+	void __iomem *reg;
+	unsigned long rate;
+	struct clk clk;
+};
+
+struct macb_config {
+	int (*txclk_init)(struct device_d *dev, struct clk **tx_clk);
+};
+
 struct macb_device {
 	void			__iomem *regs;
 

@@ -666,12 +677,101 @@ static void macb_init_rx_buffer_size(struct macb_device *bp, size_t size)
 		   size, bp->rx_buffer_size);
 }
 
+static struct sifive_fu540_macb_mgmt *mgmt;
+
+static unsigned long fu540_macb_tx_recalc_rate(struct clk *clk,
+					       unsigned long parent_rate)
+{
+	return mgmt->rate;
+}