clk: shmobile: r8a7779: Add clocks support

The R8A7779 SoC has several clocks that are too custom to be supported in a
generic driver. Those clocks are all fixed rate clocks with multiplier and
divisor set according to boot mode configuration.

Based on work for R-Car Gen2 SoCs by Laurent Pinchart.

Cc: devicetree@vger.kernel.org
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

Documentation/devicetree/bindings/clock/renesas,r8a7779-cpg-clocks.txt

+* Renesas R8A7779 Clock Pulse Generator (CPG)
+
+The CPG generates core clocks for the R8A7779. It includes one PLL and
+several fixed ratio dividers
+
+Required Properties:
+
+  - compatible: Must be "renesas,r8a7779-cpg-clocks"
+  - reg: Base address and length of the memory resource used by the CPG
+
+  - clocks: Reference to the parent clock
+  - #clock-cells: Must be 1
+  - clock-output-names: The names of the clocks. Supported clocks are "plla",
+    "z", "zs", "s", "s1", "p", "b", "out".
+
+
+Example
+-------
+
+	cpg_clocks: cpg_clocks@ffc80000 {
+		compatible = "renesas,r8a7779-cpg-clocks";
+		reg = <0 0xffc80000 0 0x30>;
+		clocks = <&extal_clk>;
+		#clock-cells = <1>;
+		clock-output-names = "plla", "z", "zs", "s", "s1", "p",
+		                     "b", "out";
+	};

drivers/clk/shmobile/Makefile

 obj-$(CONFIG_ARCH_EMEV2)		+= clk-emev2.o
 obj-$(CONFIG_ARCH_R7S72100)		+= clk-rz.o
+obj-$(CONFIG_ARCH_R8A7779)		+= clk-r8a7779.o
 obj-$(CONFIG_ARCH_R8A7790)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_R8A7791)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= clk-div6.o

drivers/clk/shmobile/clk-r8a7779.c

+/*
+ * r8a7779 Core CPG Clocks
+ *
+ * Copyright (C) 2013, 2014 Horms Solutions Ltd.
+ *
+ * Contact: Simon Horman <horms@verge.net.au>
+ *
+ * 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.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/shmobile.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/spinlock.h>
+
+#include <dt-bindings/clock/r8a7779-clock.h>
+
+#define CPG_NUM_CLOCKS			(R8A7779_CLK_OUT + 1)
+
+struct r8a7779_cpg {
+	struct clk_onecell_data data;
+	spinlock_t lock;
+	void __iomem *reg;
+};
+
+/* -----------------------------------------------------------------------------
+ * CPG Clock Data
+ */
+
+/*
+ *		MD1 = 1			MD1 = 0
+ *		(PLLA = 1500)		(PLLA = 1600)
+ *		(MHz)			(MHz)
+ *------------------------------------------------+--------------------
+ * clkz		1000   (2/3)		800   (1/2)
+ * clkzs	 250   (1/6)		200   (1/8)
+ * clki		 750   (1/2)		800   (1/2)
+ * clks		 250   (1/6)		200   (1/8)
+ * clks1	 125   (1/12)		100   (1/16)
+ * clks3	 187.5 (1/8)		200   (1/8)
+ * clks4	  93.7 (1/16)		100   (1/16)
+ * clkp		  62.5 (1/24)		 50   (1/32)
+ * clkg		  62.5 (1/24)		 66.6 (1/24)
+ * clkb, CLKOUT
+ * (MD2 = 0)	  62.5 (1/24)		 66.6 (1/24)
+ * (MD2 = 1)	  41.6 (1/36)		 50   (1/32)
+ */
+
+#define CPG_CLK_CONFIG_INDEX(md)	(((md) & (BIT(2)|BIT(1))) >> 1)
+
+struct cpg_clk_config {
+	unsigned int z_mult;
+	unsigned int z_div;
+	unsigned int zs_and_s_div;
+	unsigned int s1_div;
+	unsigned int p_div;
+	unsigned int b_and_out_div;
+};
+
+static const struct cpg_clk_config cpg_clk_configs[4] __initconst = {
+	{ 1, 2, 8, 16, 32, 24 },
+	{ 2, 3, 6, 12, 24, 24 },
+	{ 1, 2, 8, 16, 32, 32 },
+	{ 2, 3, 6, 12, 24, 36 },
+};
+
+/*
+ *   MD		PLLA Ratio
+ * 12 11
+ *------------------------
+ * 0  0		x42
+ * 0  1		x48
+ * 1  0		x56
+ * 1  1		x64
+ */
+
+#define CPG_PLLA_MULT_INDEX(md)	(((md) & (BIT(12)|BIT(11))) >> 11)
+
+static const unsigned int cpg_plla_mult[4] __initconst = { 42, 48, 56, 64 };
+
+/* -----------------------------------------------------------------------------
+ * Initialization
+ */
+
+static u32 cpg_mode __initdata;
+
+static struct clk * __init
+r8a7779_cpg_register_clock(struct device_node *np, struct r8a7779_cpg *cpg,
+			   const struct cpg_clk_config *config,
+			   unsigned int plla_mult, const char *name)
+{
+	const char *parent_name = "plla";
+	unsigned int mult = 1;
+	unsigned int div = 1;
+
+	if (!strcmp(name, "plla")) {
+		parent_name = of_clk_get_parent_name(np, 0);
+		mult = plla_mult;
+	} else if (!strcmp(name, "z")) {
+		div = config->z_div;
+		mult = config->z_mult;
+	} else if (!strcmp(name, "zs") || !strcmp(name, "s")) {
+		div = config->zs_and_s_div;
+	} else if (!strcmp(name, "s1")) {
+		div = config->s1_div;
+	} else if (!strcmp(name, "p")) {
+		div = config->p_div;
+	} else if (!strcmp(name, "b") || !strcmp(name, "out")) {
+		div = config->b_and_out_div;
+	} else {
+		return ERR_PTR(-EINVAL);
+	}
+
+	return clk_register_fixed_factor(NULL, name, parent_name, 0, mult, div);
+}
+
+static void __init r8a7779_cpg_clocks_init(struct device_node *np)
+{
+	const struct cpg_clk_config *config;
+	struct r8a7779_cpg *cpg;
+	struct clk **clks;
+	unsigned int i, plla_mult;
+	int num_clks;
+
+	num_clks = of_property_count_strings(np, "clock-output-names");
+	if (num_clks < 0) {
+		pr_err("%s: failed to count clocks\n", __func__);
+		return;
+	}
+
+	cpg = kzalloc(sizeof(*cpg), GFP_KERNEL);
+	clks = kzalloc(CPG_NUM_CLOCKS * sizeof(*clks), GFP_KERNEL);
+	if (cpg == NULL || clks == NULL) {
+		/* We're leaking memory on purpose, there's no point in cleaning
+		 * up as the system won't boot anyway.
+		 */
+		return;
+	}
+
+	spin_lock_init(&cpg->lock);
+
+	cpg->data.clks = clks;
+	cpg->data.clk_num = num_clks;
+
+	config = &cpg_clk_configs[CPG_CLK_CONFIG_INDEX(cpg_mode)];
+	plla_mult = cpg_plla_mult[CPG_PLLA_MULT_INDEX(cpg_mode)];
+
+	for (i = 0; i < num_clks; ++i) {
+		const char *name;
+		struct clk *clk;
+
+		of_property_read_string_index(np, "clock-output-names", i,
+					      &name);
+
+		clk = r8a7779_cpg_register_clock(np, cpg, config,
+						 plla_mult, name);
+		if (IS_ERR(clk))
+			pr_err("%s: failed to register %s %s clock (%ld)\n",
+			       __func__, np->name, name, PTR_ERR(clk));
+		else
+			cpg->data.clks[i] = clk;
+	}
+
+	of_clk_add_provider(np, of_clk_src_onecell_get, &cpg->data);
+}
+CLK_OF_DECLARE(r8a7779_cpg_clks, "renesas,r8a7779-cpg-clocks",
+	       r8a7779_cpg_clocks_init);
+
+void __init r8a7779_clocks_init(u32 mode)
+{
+	cpg_mode = mode;
+
+	of_clk_init(NULL);
+}

include/linux/clk/shmobile.h

 /*
  * Copyright 2013 Ideas On Board SPRL
+ * Copyright 2013, 2014 Horms Solutions Ltd.
  *
  * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ * Contact: Simon Horman <horms@verge.net.au>
  *
  * 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
@@ -14,6 +16,7 @@
 
 #include <linux/types.h>
 
+void r8a7779_clocks_init(u32 mode);
 void rcar_gen2_clocks_init(u32 mode);
 
 #endif