clk: add MOXA ART SoCs clock driver

MOXA ART SoCs allow to determine PLL output and APB frequencies
by reading registers holding multiplier and divisor information.

Add a clock driver for this SoC.

Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

2 files changed, 98 insertions, 0 deletions

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index a367a9831717..48a7ef3d05f6 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_ARCH_EFM32)		+= clk-efm32gg.o
 obj-$(CONFIG_ARCH_HIGHBANK)		+= clk-highbank.o
 obj-$(CONFIG_MACH_LOONGSON1)		+= clk-ls1x.o
 obj-$(CONFIG_COMMON_CLK_MAX77686)	+= clk-max77686.o
+obj-$(CONFIG_ARCH_MOXART)		+= clk-moxart.o
 obj-$(CONFIG_ARCH_NOMADIK)		+= clk-nomadik.o
 obj-$(CONFIG_ARCH_NSPIRE)		+= clk-nspire.o
 obj-$(CONFIG_CLK_PPC_CORENET)		+= clk-ppc-corenet.o
diff --git a/drivers/clk/clk-moxart.c b/drivers/clk/clk-moxart.c
new file mode 100644
index 000000000000..30a3b6999e10
--- /dev/null
+++ b/drivers/clk/clk-moxart.c
@@ -0,0 +1,97 @@
+/*
+ * MOXA ART SoCs clock driver.
+ *
+ * Copyright (C) 2013 Jonas Jensen
+ *
+ * Jonas Jensen <jonas.jensen@gmail.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/io.h>
+#include <linux/of_address.h>
+#include <linux/clkdev.h>
+
+void __init moxart_of_pll_clk_init(struct device_node *node)
+{
+	static void __iomem *base;
+	struct clk *clk, *ref_clk;
+	unsigned int mul;
+	const char *name = node->name;
+	const char *parent_name;
+
+	of_property_read_string(node, "clock-output-names", &name);
+	parent_name = of_clk_get_parent_name(node, 0);
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		pr_err("%s: of_iomap failed\n", node->full_name);
+		return;
+	}
+
+	mul = readl(base + 0x30) >> 3 & 0x3f;
+	iounmap(base);
+
+	ref_clk = of_clk_get(node, 0);
+	if (IS_ERR(ref_clk)) {
+		pr_err("%s: of_clk_get failed\n", node->full_name);
+		return;
+	}
+
+	clk = clk_register_fixed_factor(NULL, name, parent_name, 0, mul, 1);
+	if (IS_ERR(clk)) {
+		pr_err("%s: failed to register clock\n", node->full_name);
+		return;
+	}
+
+	clk_register_clkdev(clk, NULL, name);
+	of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+CLK_OF_DECLARE(moxart_pll_clock, "moxa,moxart-pll-clock",
+	       moxart_of_pll_clk_init);
+
+void __init moxart_of_apb_clk_init(struct device_node *node)
+{
+	static void __iomem *base;
+	struct clk *clk, *pll_clk;
+	unsigned int div, val;
+	unsigned int div_idx[] = { 2, 3, 4, 6, 8};
+	const char *name = node->name;
+	const char *parent_name;
+
+	of_property_read_string(node, "clock-output-names", &name);
+	parent_name = of_clk_get_parent_name(node, 0);
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		pr_err("%s: of_iomap failed\n", node->full_name);
+		return;
+	}
+
+	val = readl(base + 0xc) >> 4 & 0x7;
+	iounmap(base);
+
+	if (val > 4)
+		val = 0;
+	div = div_idx[val] * 2;
+
+	pll_clk = of_clk_get(node, 0);
+	if (IS_ERR(pll_clk)) {
+		pr_err("%s: of_clk_get failed\n", node->full_name);
+		return;
+	}
+
+	clk = clk_register_fixed_factor(NULL, name, parent_name, 0, 1, div);
+	if (IS_ERR(clk)) {
+		pr_err("%s: failed to register clock\n", node->full_name);
+		return;
+	}
+
+	clk_register_clkdev(clk, NULL, name);
+	of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+CLK_OF_DECLARE(moxart_apb_clock, "moxa,moxart-apb-clock",
+	       moxart_of_apb_clk_init);