clk: clk_octeon: Add simple MIPS Octeon clock driver

This patch adds a simple clock driver for the Marvell Octeon MIPS SoC
family. Its for IO clock rate passing via DT in some of the Octeon
driver, like I2C. So that we don't need to use the non-mainline API
octeon_get_io_clock().

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Lukasz Majewski <lukma@denx.de>

drivers/clk/Kconfig

@@ -83,6 +83,13 @@ config CLK_INTEL
 	  set up by U-Boot itself but only statically. Thus the driver does not
 	  support changing clock rates, only querying them.
 
+config CLK_OCTEON
+	bool "Clock controller driver for Marvell MIPS Octeon"
+	depends on CLK && ARCH_OCTEON
+	default y
+	help
+	  Enable this to support the clocks on Octeon MIPS platforms.
+
 config CLK_STM32F
 	bool "Enable clock driver support for STM32F family"
 	depends on CLK && (STM32F7 || STM32F4)

drivers/clk/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_$(SPL_TPL_)CLK_INTEL) += intel/
 obj-$(CONFIG_CLK_HSDK) += clk-hsdk-cgu.o
 obj-$(CONFIG_CLK_K210) += kendryte/
 obj-$(CONFIG_CLK_MPC83XX) += mpc83xx_clk.o
+obj-$(CONFIG_CLK_OCTEON) += clk_octeon.o
 obj-$(CONFIG_CLK_OWL) += owl/
 obj-$(CONFIG_CLK_RENESAS) += renesas/
 obj-$(CONFIG_CLK_SIFIVE) += sifive/

drivers/clk/clk_octeon.c

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Stefan Roese <sr@denx.de>
+ */
+
+#include <clk-uclass.h>
+#include <dm.h>
+#include <dt-bindings/clock/octeon-clock.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct octeon_clk_priv {
+	u64 core_clk;
+	u64 io_clk;
+};
+
+static int octeon_clk_enable(struct clk *clk)
+{
+	/* Nothing to do on Octeon */
+	return 0;
+}
+
+static ulong octeon_clk_get_rate(struct clk *clk)
+{
+	struct octeon_clk_priv *priv = dev_get_priv(clk->dev);
+
+	switch (clk->id) {
+	case OCTEON_CLK_CORE:
+		return priv->core_clk;
+
+	case OCTEON_CLK_IO:
+		return priv->io_clk;
+
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+static struct clk_ops octeon_clk_ops = {
+	.enable = octeon_clk_enable,
+	.get_rate = octeon_clk_get_rate,
+};
+
+static const struct udevice_id octeon_clk_ids[] = {
+	{ .compatible = "mrvl,octeon-clk" },
+	{ /* sentinel */ }
+};
+
+static int octeon_clk_probe(struct udevice *dev)
+{
+	struct octeon_clk_priv *priv = dev_get_priv(dev);
+
+	/*
+	 * The clock values are already read into GD, lets just store them
+	 * in priv data
+	 */
+	priv->core_clk = gd->cpu_clk;
+	priv->io_clk = gd->bus_clk;
+
+	return 0;
+}
+
+U_BOOT_DRIVER(clk_octeon) = {
+	.name = "clk_octeon",
+	.id = UCLASS_CLK,
+	.of_match = octeon_clk_ids,
+	.ops = &octeon_clk_ops,
+	.probe = octeon_clk_probe,
+	.priv_auto_alloc_size = sizeof(struct octeon_clk_priv),
+};

include/dt-bindings/clock/octeon-clock.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2020 Stefan Roese <sr@denx.de>
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_OCTEON_CLOCK_H
+#define __DT_BINDINGS_CLOCK_OCTEON_CLOCK_H
+
+#define OCTEON_CLK_CORE		0
+#define OCTEON_CLK_IO		1
+
+#endif /* __DT_BINDINGS_CLOCK_OCTEON_CLOCK_H */