clk: emev2: Add support for emev2 SMU clocks with DT

Device tree clock binding document for EMMA Mobile EV2 SMU,
And Common clock framework based implementation of it.
Following nodes are defined to describe clock tree.
- renesas,emev2-smu
- renesas,emev2-smu-clkdiv
- renesas,emev2-smu-gclk

These bindings are designed manually based on
 19UH0037EJ1000_SMU : System Management Unit User's Manual

So far, reparent is not implemented, and is fixed to index #0.
Clock tree description is not included, and should be provided
by device-tree.
Signed-off-by: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/clock/emev2-clock.txt

+Device tree Clock bindings for Renesas EMMA Mobile EV2
+
+This binding uses the common clock binding.
+
+* SMU
+System Management Unit described in user's manual R19UH0037EJ1000_SMU.
+This is not a clock provider, but clocks under SMU depend on it.
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu"
+- reg: Address and Size of SMU registers
+
+* SMU_CLKDIV
+Function block with an input mux and a divider, which corresponds to
+"Serial clock generator" in fig."Clock System Overview" of the manual,
+and "xxx frequency division setting register" (XXXCLKDIV) registers.
+This makes internal (neither input nor output) clock that is provided
+to input of xxxGCLK block.
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu-clkdiv"
+- reg: Byte offset from SMU base and Bit position in the register
+- clocks: Parent clocks. Input clocks as described in clock-bindings.txt
+- #clock-cells: Should be <0>
+
+* SMU_GCLK
+Clock gating node shown as "Clock stop processing block" in the
+fig."Clock System Overview" of the manual.
+Registers are "xxx clock gate control register" (XXXGCLKCTRL).
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu-gclk"
+- reg: Byte offset from SMU base and Bit position in the register
+- clocks: Input clock as described in clock-bindings.txt
+- #clock-cells: Should be <0>
+
+Example of provider:
+
+usia_u0_sclkdiv: usia_u0_sclkdiv {
+	compatible = "renesas,emev2-smu-clkdiv";
+	reg = <0x610 0>;
+	clocks = <&pll3_fo>, <&pll4_fo>, <&pll1_fo>, <&osc1_fo>;
+	#clock-cells = <0>;
+};
+
+usia_u0_sclk: usia_u0_sclk {
+	compatible = "renesas,emev2-smu-gclk";
+	reg = <0x4a0 1>;
+	clocks = <&usia_u0_sclkdiv>;
+	#clock-cells = <0>;
+};
+
+Example of consumer:
+
+uart@e1020000 {
+	compatible = "renesas,em-uart";
+	reg = <0xe1020000 0x38>;
+	interrupts = <0 8 0>;
+	clocks = <&usia_u0_sclk>;
+	clock-names = "sclk";
+};
+
+Example of clock-tree description:
+
+ This describes a clock path in the clock tree
+  c32ki -> pll3_fo -> usia_u0_sclkdiv -> usia_u0_sclk
+
+smu@e0110000 {
+	compatible = "renesas,emev2-smu";
+	reg = <0xe0110000 0x10000>;
+	#address-cells = <2>;
+	#size-cells = <0>;
+
+	c32ki: c32ki {
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+		#clock-cells = <0>;
+	};
+	pll3_fo: pll3_fo {
+		compatible = "fixed-factor-clock";
+		clocks = <&c32ki>;
+		clock-div = <1>;
+		clock-mult = <7000>;
+		#clock-cells = <0>;
+	};
+	usia_u0_sclkdiv: usia_u0_sclkdiv {
+		compatible = "renesas,emev2-smu-clkdiv";
+		reg = <0x610 0>;
+		clocks = <&pll3_fo>;
+		#clock-cells = <0>;
+	};
+	usia_u0_sclk: usia_u0_sclk {
+		compatible = "renesas,emev2-smu-gclk";
+		reg = <0x4a0 1>;
+		clocks = <&usia_u0_sclkdiv>;
+		#clock-cells = <0>;
+	};
+};

drivers/clk/shmobile/Makefile

+obj-$(CONFIG_ARCH_EMEV2)		+= clk-emev2.o
 obj-$(CONFIG_ARCH_R8A7790)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_R8A7791)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= clk-div6.o
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= clk-mstp.o
-
 # for emply built-in.o
 obj-n	:= dummy

drivers/clk/shmobile/clk-emev2.c

+/*
+ * EMMA Mobile EV2 common clock framework support
+ *
+ * Copyright (C) 2013 Takashi Yoshii <takashi.yoshii.ze@renesas.com>
+ * Copyright (C) 2012 Magnus Damm
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+/* EMEV2 SMU registers */
+#define USIAU0_RSTCTRL 0x094
+#define USIBU1_RSTCTRL 0x0ac
+#define USIBU2_RSTCTRL 0x0b0
+#define USIBU3_RSTCTRL 0x0b4
+#define STI_RSTCTRL 0x124
+#define STI_CLKSEL 0x688
+
+static DEFINE_SPINLOCK(lock);
+
+/* not pretty, but hey */
+void __iomem *smu_base;
+
+static void __init emev2_smu_write(unsigned long value, int offs)
+{
+	BUG_ON(!smu_base || (offs >= PAGE_SIZE));
+	writel_relaxed(value, smu_base + offs);
+}
+
+static const struct of_device_id smu_id[] __initconst = {
+	{ .compatible = "renesas,emev2-smu", },
+	{},
+};
+
+static void __init emev2_smu_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, smu_id);
+	BUG_ON(!np);
+	smu_base = of_iomap(np, 0);
+	BUG_ON(!smu_base);
+	of_node_put(np);
+
+	/* setup STI timer to run on 32.768 kHz and deassert reset */
+	emev2_smu_write(0, STI_CLKSEL);
+	emev2_smu_write(1, STI_RSTCTRL);
+
+	/* deassert reset for UART0->UART3 */
+	emev2_smu_write(2, USIAU0_RSTCTRL);
+	emev2_smu_write(2, USIBU1_RSTCTRL);
+	emev2_smu_write(2, USIBU2_RSTCTRL);
+	emev2_smu_write(2, USIBU3_RSTCTRL);
+}
+
+static void __init emev2_smu_clkdiv_init(struct device_node *np)
+{
+	u32 reg[2];
+	struct clk *clk;
+	const char *parent_name = of_clk_get_parent_name(np, 0);
+	if (WARN_ON(of_property_read_u32_array(np, "reg", reg, 2)))
+		return;
+	if (!smu_base)
+		emev2_smu_init();
+	clk = clk_register_divider(NULL, np->name, parent_name, 0,
+				   smu_base + reg[0], reg[1], 8, 0, &lock);
+	of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	clk_register_clkdev(clk, np->name, NULL);
+	pr_debug("## %s %s %p\n", __func__, np->name, clk);
+}
+CLK_OF_DECLARE(emev2_smu_clkdiv, "renesas,emev2-smu-clkdiv",
+		emev2_smu_clkdiv_init);
+
+static void __init emev2_smu_gclk_init(struct device_node *np)
+{
+	u32 reg[2];
+	struct clk *clk;
+	const char *parent_name = of_clk_get_parent_name(np, 0);
+	if (WARN_ON(of_property_read_u32_array(np, "reg", reg, 2)))
+		return;
+	if (!smu_base)
+		emev2_smu_init();
+	clk = clk_register_gate(NULL, np->name, parent_name, 0,
+				smu_base + reg[0], reg[1], 0, &lock);
+	of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	clk_register_clkdev(clk, np->name, NULL);
+	pr_debug("## %s %s %p\n", __func__, np->name, clk);
+}
+CLK_OF_DECLARE(emev2_smu_gclk, "renesas,emev2-smu-gclk", emev2_smu_gclk_init);