clk: mvebu: Add the xtal clock for Armada 3700 SoC

This clock is the parent of all the Armada 3700 clocks. It is a fixed
rate clock which depends on the gpio configuration read when resetting
the SoC.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/mvebu/Kconfig

@@ -24,6 +24,9 @@ config ARMADA_39X_CLK
 	bool
 	select MVEBU_CLK_COMMON
 
+config ARMADA_37XX_CLK
+       bool
+
 config ARMADA_XP_CLK
 	bool
 	select MVEBU_CLK_COMMON

drivers/clk/mvebu/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_ARMADA_370_CLK)	+= armada-370.o
 obj-$(CONFIG_ARMADA_375_CLK)	+= armada-375.o
 obj-$(CONFIG_ARMADA_38X_CLK)	+= armada-38x.o
 obj-$(CONFIG_ARMADA_39X_CLK)	+= armada-39x.o
+obj-$(CONFIG_ARMADA_37XX_CLK)	+= armada-37xx-xtal.o
 obj-$(CONFIG_ARMADA_XP_CLK)	+= armada-xp.o
 obj-$(CONFIG_ARMADA_AP806_SYSCON) += ap806-system-controller.o
 obj-$(CONFIG_ARMADA_CP110_SYSCON) += cp110-system-controller.o

drivers/clk/mvebu/armada-37xx-xtal.c

+/*
+ * Marvell Armada 37xx SoC xtal clocks
+ *
+ * Copyright (C) 2016 Marvell
+ *
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define NB_GPIO1_LATCH	0xC
+#define XTAL_MODE	    BIT(31)
+
+static int armada_3700_xtal_clock_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const char *xtal_name = "xtal";
+	struct device_node *parent;
+	struct regmap *regmap;
+	struct clk_hw *xtal_hw;
+	unsigned int rate;
+	u32 reg;
+	int ret;
+
+	xtal_hw = devm_kzalloc(&pdev->dev, sizeof(*xtal_hw), GFP_KERNEL);
+	if (!xtal_hw)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, xtal_hw);
+
+	parent = np->parent;
+	if (!parent) {
+		dev_err(&pdev->dev, "no parent\n");
+		return -ENODEV;
+	}
+
+	regmap = syscon_node_to_regmap(parent);
+	if (IS_ERR(regmap)) {
+		dev_err(&pdev->dev, "cannot get regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	ret = regmap_read(regmap, NB_GPIO1_LATCH, &reg);
+	if (ret) {
+		dev_err(&pdev->dev, "cannot read from regmap\n");
+		return ret;
+	}
+
+	if (reg & XTAL_MODE)
+		rate = 40000000;
+	else
+		rate = 25000000;
+
+	of_property_read_string_index(np, "clock-output-names", 0, &xtal_name);
+	xtal_hw = clk_hw_register_fixed_rate(NULL, xtal_name, NULL, 0, rate);
+	if (IS_ERR(xtal_hw))
+		return PTR_ERR(xtal_hw);
+	ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, xtal_hw);
+
+	return ret;
+}
+
+static int armada_3700_xtal_clock_remove(struct platform_device *pdev)
+{
+	of_clk_del_provider(pdev->dev.of_node);
+
+	return 0;
+}
+
+static const struct of_device_id armada_3700_xtal_clock_of_match[] = {
+	{ .compatible = "marvell,armada-3700-xtal-clock", },
+	{ }
+};
+
+static struct platform_driver armada_3700_xtal_clock_driver = {
+	.probe = armada_3700_xtal_clock_probe,
+	.remove = armada_3700_xtal_clock_remove,
+	.driver		= {
+		.name	= "marvell-armada-3700-xtal-clock",
+		.of_match_table = armada_3700_xtal_clock_of_match,
+	},
+};
+
+builtin_platform_driver(armada_3700_xtal_clock_driver);