net: txgbe: Register fixed rate clock

In order for I2C to be able to work in standard mode, register a fixed
rate clock for each I2C device.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/wangxun/Kconfig

@@ -40,6 +40,7 @@ config NGBE
 config TXGBE
 	tristate "Wangxun(R) 10GbE PCI Express adapters support"
 	depends on PCI
+	depends on COMMON_CLK
 	select LIBWX
 	help
 	  This driver supports Wangxun(R) 10GbE PCI Express family of

drivers/net/ethernet/wangxun/txgbe/txgbe_phy.c

@@ -2,6 +2,8 @@
 /* Copyright (c) 2015 - 2023 Beijing WangXun Technology Co., Ltd. */
 
 #include <linux/gpio/property.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
 #include <linux/i2c.h>
 #include <linux/pci.h>
 
@@ -70,6 +72,32 @@ static int txgbe_swnodes_register(struct txgbe *txgbe)
 	return software_node_register_node_group(nodes->group);
 }
 
+static int txgbe_clock_register(struct txgbe *txgbe)
+{
+	struct pci_dev *pdev = txgbe->wx->pdev;
+	struct clk_lookup *clock;
+	char clk_name[32];
+	struct clk *clk;
+
+	snprintf(clk_name, sizeof(clk_name), "i2c_designware.%d",
+		 (pdev->bus->number << 8) | pdev->devfn);
+
+	clk = clk_register_fixed_rate(NULL, clk_name, NULL, 0, 156250000);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	clock = clkdev_create(clk, NULL, clk_name);
+	if (!clock) {
+		clk_unregister(clk);
+		return -ENOMEM;
+	}
+
+	txgbe->clk = clk;
+	txgbe->clock = clock;
+
+	return 0;
+}
+
 int txgbe_init_phy(struct txgbe *txgbe)
 {
 	int ret;
@@ -80,10 +108,23 @@ int txgbe_init_phy(struct txgbe *txgbe)
 		return ret;
 	}
 
+	ret = txgbe_clock_register(txgbe);
+	if (ret) {
+		wx_err(txgbe->wx, "failed to register clock: %d\n", ret);
+		goto err_unregister_swnode;
+	}
+
 	return 0;
+
+err_unregister_swnode:
+	software_node_unregister_node_group(txgbe->nodes.group);
+
+	return ret;
 }
 
 void txgbe_remove_phy(struct txgbe *txgbe)
 {
+	clkdev_drop(txgbe->clock);
+	clk_unregister(txgbe->clk);
 	software_node_unregister_node_group(txgbe->nodes.group);
 }

drivers/net/ethernet/wangxun/txgbe/txgbe_type.h

@@ -147,6 +147,8 @@ struct txgbe_nodes {
 struct txgbe {
 	struct wx *wx;
 	struct txgbe_nodes nodes;
+	struct clk_lookup *clock;
+	struct clk *clk;
 };
 
 #endif /* _TXGBE_TYPE_H_ */