clk: sifive: Add clock driver for GEMGXL MGMT

This adds a clock driver to support the GEMGXL management IP block
found in FU540 SoCs to control GEM TX clock operation mode for
10/100/1000 Mbps.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Tested-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>

drivers/clk/sifive/Kconfig

@@ -17,3 +17,10 @@ config CLK_SIFIVE_FU540_PRCI
 	  Supports the Power Reset Clock interface (PRCI) IP block found in
 	  FU540 SoCs.  If this kernel is meant to run on a SiFive FU540 SoC,
 	  enable this driver.
+
+config CLK_SIFIVE_GEMGXL_MGMT
+	bool "GEMGXL management for SiFive FU540 SoCs"
+	depends on CLK_SIFIVE
+	help
+	  Supports the GEMGXL management IP block found in FU540 SoCs to
+	  control GEM TX clock operation mode for 10/100/1000 Mbps.

drivers/clk/sifive/Makefile

@@ -3,3 +3,5 @@
 obj-$(CONFIG_CLK_ANALOGBITS_WRPLL_CLN28HPC)	+= wrpll-cln28hpc.o
 
 obj-$(CONFIG_CLK_SIFIVE_FU540_PRCI)		+= fu540-prci.o
+
+obj-$(CONFIG_CLK_SIFIVE_GEMGXL_MGMT)		+= gemgxl-mgmt.o

drivers/clk/sifive/gemgxl-mgmt.c

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019, Bin Meng <bmeng.cn@gmail.com>
+ */
+
+#include <common.h>
+#include <clk-uclass.h>
+#include <dm.h>
+#include <asm/io.h>
+
+struct gemgxl_mgmt_regs {
+	__u32 tx_clk_sel;
+};
+
+struct gemgxl_mgmt_platdata {
+	struct gemgxl_mgmt_regs *regs;
+};
+
+static int gemgxl_mgmt_ofdata_to_platdata(struct udevice *dev)
+{
+	struct gemgxl_mgmt_platdata *plat = dev_get_platdata(dev);
+
+	plat->regs = (struct gemgxl_mgmt_regs *)dev_read_addr(dev);
+
+	return 0;
+}
+
+static ulong gemgxl_mgmt_set_rate(struct clk *clk, ulong rate)
+{
+	struct gemgxl_mgmt_platdata *plat = dev_get_platdata(clk->dev);
+
+	/*
+	 * GEMGXL TX clock operation mode:
+	 *
+	 * 0 = GMII mode. Use 125 MHz gemgxlclk from PRCI in TX logic
+	 *     and output clock on GMII output signal GTX_CLK
+	 * 1 = MII mode. Use MII input signal TX_CLK in TX logic
+	 */
+	writel(rate != 125000000, &plat->regs->tx_clk_sel);
+
+	return 0;
+}
+
+const struct clk_ops gemgxl_mgmt_ops = {
+	.set_rate = gemgxl_mgmt_set_rate,
+};
+
+static const struct udevice_id gemgxl_mgmt_match[] = {
+	{ .compatible = "sifive,cadencegemgxlmgmt0", },
+	{ /* sentinel */ }
+};
+
+U_BOOT_DRIVER(sifive_gemgxl_mgmt) = {
+	.name = "sifive-gemgxl-mgmt",
+	.id = UCLASS_CLK,
+	.of_match = gemgxl_mgmt_match,
+	.ofdata_to_platdata = gemgxl_mgmt_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct gemgxl_mgmt_platdata),
+	.ops = &gemgxl_mgmt_ops,
+};