clk: x86: Add ST oscout platform clock

Stoney SoC provides oscout clock. This clock can support 25Mhz and
48Mhz of frequency.
The clock is available for general system use.
Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/clk/x86/Makefile

+obj-$(CONFIG_PMC_ATOM)		+= clk-pmc-atom.o
+obj-$(CONFIG_X86_AMD_PLATFORM_DEVICE)	+= clk-st.o
 clk-x86-lpss-objs		:= clk-lpt.o
 obj-$(CONFIG_X86_INTEL_LPSS)	+= clk-x86-lpss.o
-obj-$(CONFIG_PMC_ATOM)		+= clk-pmc-atom.o

drivers/clk/x86/clk-st.c

+// SPDX-License-Identifier: MIT
+/*
+ * clock framework for AMD Stoney based clocks
+ *
+ * Copyright 2018 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/platform_data/clk-st.h>
+#include <linux/platform_device.h>
+
+/* Clock Driving Strength 2 register */
+#define CLKDRVSTR2	0x28
+/* Clock Control 1 register */
+#define MISCCLKCNTL1	0x40
+/* Auxiliary clock1 enable bit */
+#define OSCCLKENB	2
+/* 25Mhz auxiliary output clock freq bit */
+#define OSCOUT1CLK25MHZ	16
+
+#define ST_CLK_48M	0
+#define ST_CLK_25M	1
+#define ST_CLK_MUX	2
+#define ST_CLK_GATE	3
+#define ST_MAX_CLKS	4
+
+static const char * const clk_oscout1_parents[] = { "clk48MHz", "clk25MHz" };
+static struct clk_hw *hws[ST_MAX_CLKS];
+
+static int st_clk_probe(struct platform_device *pdev)
+{
+	struct st_clk_data *st_data;
+
+	st_data = dev_get_platdata(&pdev->dev);
+	if (!st_data || !st_data->base)
+		return -EINVAL;
+
+	hws[ST_CLK_48M] = clk_hw_register_fixed_rate(NULL, "clk48MHz", NULL, 0,
+						     48000000);
+	hws[ST_CLK_25M] = clk_hw_register_fixed_rate(NULL, "clk25MHz", NULL, 0,
+						     25000000);
+
+	hws[ST_CLK_MUX] = clk_hw_register_mux(NULL, "oscout1_mux",
+		clk_oscout1_parents, ARRAY_SIZE(clk_oscout1_parents),
+		0, st_data->base + CLKDRVSTR2, OSCOUT1CLK25MHZ, 3, 0, NULL);
+
+	clk_set_parent(hws[ST_CLK_MUX]->clk, hws[ST_CLK_25M]->clk);
+
+	hws[ST_CLK_GATE] = clk_hw_register_gate(NULL, "oscout1", "oscout1_mux",
+		0, st_data->base + MISCCLKCNTL1, OSCCLKENB,
+		CLK_GATE_SET_TO_DISABLE, NULL);
+
+	clk_hw_register_clkdev(hws[ST_CLK_GATE], "oscout1", NULL);
+
+	return 0;
+}
+
+static int st_clk_remove(struct platform_device *pdev)
+{
+	int i;
+
+	for (i = 0; i < ST_MAX_CLKS; i++)
+		clk_hw_unregister(hws[i]);
+	return 0;
+}
+
+static struct platform_driver st_clk_driver = {
+	.driver = {
+		.name = "clk-st",
+		.suppress_bind_attrs = true,
+	},
+	.probe = st_clk_probe,
+	.remove = st_clk_remove,
+};
+builtin_platform_driver(st_clk_driver);

include/linux/platform_data/clk-st.h

+/* SPDX-License-Identifier: MIT */
+/*
+ * clock framework for AMD Stoney based clock
+ *
+ * Copyright 2018 Advanced Micro Devices, Inc.
+ */
+
+#ifndef __CLK_ST_H
+#define __CLK_ST_H
+
+#include <linux/compiler.h>
+
+struct st_clk_data {
+	void __iomem *base;
+};
+
+#endif /* __CLK_ST_H */