[PATCH net-next 01/11] net: stmmac: provide set_clk_tx_rate() hook

[Russell King (Oracle)]

Several stmmac sub-drivers which support RGMII follow the same pattern.
They calculate the transmit clock rate, and then call clk_set_rate().

Analysis of several implementation documents suggests that the platform
is responsible for providing the transmit clock to the DWMAC core's
clk_tx_i. The expected rates are:

	10Mbps	100Mbps	1Gbps
MII	2.5MHz	25MHz
RMII	2.5MHz	25MHz
GMII			125MHz
RGMI	2.5MHz	25MHz	125MHz

It seems some platforms require this clock to be manually configured,
but there are outputs from the MAC core that indicate the speed, so a
platform may use these to automatically configure the clock. Thus, we
can't just provide one solution to configure this clock rate.

Moreover, the clock may need to be derived from one of several sources
depending on the interface mode.

Provide a platform hook that is passed the transmit clock, interface
mode and speed.

Reviewed-by: Thierry Reding <treding at nvidia.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 11 +++++++++++
 include/linux/stmmac.h                            |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 424fa2fe31c6..e66cd6889728 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -928,6 +928,7 @@ static void stmmac_mac_link_up(struct phylink_config *config,
 	struct stmmac_priv *priv = netdev_priv(to_net_dev(config->dev));
 	unsigned int flow_ctrl;
 	u32 old_ctrl, ctrl;
+	int ret;
 
 	if ((priv->plat->flags & STMMAC_FLAG_SERDES_UP_AFTER_PHY_LINKUP) &&
 	    priv->plat->serdes_powerup)
@@ -1020,6 +1021,16 @@ static void stmmac_mac_link_up(struct phylink_config *config,
 	if (ctrl != old_ctrl)
 		writel(ctrl, priv->ioaddr + MAC_CTRL_REG);
 
+	if (priv->plat->set_clk_tx_rate) {
+		ret = priv->plat->set_clk_tx_rate(priv->plat->bsp_priv,
+						priv->plat->clk_tx_i,
+						interface, speed);
+		if (ret < 0)
+			netdev_err(priv->dev,
+				   "failed to configure transmit clock for %dMbps: %pe\n",
+				   speed, ERR_PTR(ret));
+	}
+
 	stmmac_mac_set(priv, priv->ioaddr, true);
 	if (priv->dma_cap.eee)
 		stmmac_set_eee_pls(priv, priv->hw, true);
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 6d2aa77ea963..cd0d1383df87 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -78,6 +78,7 @@
 			| DMA_AXI_BLEN_32 | DMA_AXI_BLEN_64 \
 			| DMA_AXI_BLEN_128 | DMA_AXI_BLEN_256)
 
+struct clk;
 struct stmmac_priv;
 
 /* Platfrom data for platform device structure's platform_data field */
@@ -231,6 +232,8 @@ struct plat_stmmacenet_data {
 	u8 tx_sched_algorithm;
 	struct stmmac_rxq_cfg rx_queues_cfg[MTL_MAX_RX_QUEUES];
 	struct stmmac_txq_cfg tx_queues_cfg[MTL_MAX_TX_QUEUES];
+	int (*set_clk_tx_rate)(void *priv, struct clk *clk_tx_i,
+			       phy_interface_t interface, int speed);
 	void (*fix_mac_speed)(void *priv, int speed, unsigned int mode);
 	int (*fix_soc_reset)(void *priv, void __iomem *ioaddr);
 	int (*serdes_powerup)(struct net_device *ndev, void *priv);
@@ -252,6 +255,7 @@ struct plat_stmmacenet_data {
 	struct clk *stmmac_clk;
 	struct clk *pclk;
 	struct clk *clk_ptp_ref;
+	struct clk *clk_tx_i;		/* clk_tx_i to MAC core */
 	unsigned long clk_ptp_rate;
 	unsigned long clk_ref_rate;
 	struct clk_bulk_data *clks;
-- 
2.30.2