clk: shmobile: Add R-Car Gen2 clocks support

The R-Car Gen2 SoCs (R8A7790 and R8A7791) have several clocks that are
too custom to be supported in a generic driver. Those clocks can be
divided in two categories:

- Fixed rate clocks with multiplier and divisor set according to boot
mode configuration

- Custom divider clocks with SoC-specific divider values

This driver supports both.

Signed-off-by: Laurent Pinchart <[e-mail]>
Acked-by: Kumar Gala <[e-mail]>
Signed-off-by: Mike Turquette <[e-mail]>

Documentation/devicetree/bindings/clock/renesas,rcar-gen2-cpg-clocks.txt

···
+* Renesas R-Car Gen2 Clock Pulse Generator (CPG)
+
+The CPG generates core clocks for the R-Car Gen2 SoCs. It includes three PLLs
+and several fixed ratio dividers.
+
+Required Properties:
+
+  - compatible: Must be one of
+    - "renesas,r8a7790-cpg-clocks" for the r8a7790 CPG
+    - "renesas,r8a7791-cpg-clocks" for the r8a7791 CPG
+    - "renesas,rcar-gen2-cpg-clocks" for the generic R-Car Gen2 CPG
+
+  - 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 "main",
+    "pll0", "pll1", "pll3", "lb", "qspi", "sdh", "sd0", "sd1" and "z"
+
+
+Example
+-------
+
+	cpg_clocks: cpg_clocks@e6150000 {
+		compatible = "renesas,r8a7790-cpg-clocks",
+			     "renesas,rcar-gen2-cpg-clocks";
+		reg = <0 0xe6150000 0 0x1000>;
+		clocks = <&extal_clk>;
+		#clock-cells = <1>;
+		clock-output-names = "main", "pll0, "pll1", "pll3",
+				     "lb", "qspi", "sdh", "sd0", "sd1", "z";
+	};

drivers/clk/Makefile

···
 obj-$(CONFIG_PLAT_SAMSUNG)	+= samsung/
 obj-$(CONFIG_COMMON_CLK_XGENE)  += clk-xgene.o
 obj-$(CONFIG_COMMON_CLK_KEYSTONE)	+= keystone/
+obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= shmobile/
 
 obj-$(CONFIG_X86)		+= x86/
 

drivers/clk/shmobile/Makefile

···
+obj-$(CONFIG_ARCH_R8A7790)		+= clk-rcar-gen2.o
+obj-$(CONFIG_ARCH_R8A7791)		+= clk-rcar-gen2.o
+
+# for emply built-in.o
+obj-n	:= dummy

drivers/clk/shmobile/clk-rcar-gen2.c

···
+/*
+ * rcar_gen2 Core CPG Clocks
+ *
+ * Copyright (C) 2013  Ideas On Board SPRL
+ *
+ * Contact: Laurent Pinchart <[e-mail]>
+ *
+ * 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/math64.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/spinlock.h>
+
+struct rcar_gen2_cpg {
+	struct clk_onecell_data data;
+	spinlock_t lock;
+	void __iomem *reg;
+};
+
+#define CPG_SDCKCR			0x00000074
+#define CPG_PLL0CR			0x000000d8
+#define CPG_FRQCRC			0x000000e0
+#define CPG_FRQCRC_ZFC_MASK		(0x1f << 8)
+#define CPG_FRQCRC_ZFC_SHIFT		8
+
+/* -----------------------------------------------------------------------------
+ * Z Clock
+ *
+ * Traits of this clock:
+ * prepare - clk_prepare only ensures that parents are prepared
+ * enable - clk_enable only ensures that parents are enabled
+ * rate - rate is adjustable.  clk->rate = parent->rate * mult / 32
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+struct cpg_z_clk {
+	struct clk_hw hw;
+	void __iomem *reg;
+};
+
+#define to_z_clk(_hw)	container_of(_hw, struct cpg_z_clk, hw)
+
+static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw,
+					   unsigned long parent_rate)
+{
+	struct cpg_z_clk *zclk = to_z_clk(hw);
+	unsigned int mult;
+	unsigned int val;
+
+	val = (clk_readl(zclk->reg) & CPG_FRQCRC_ZFC_MASK)
+	    >> CPG_FRQCRC_ZFC_SHIFT;
+	mult = 32 - val;
+
+	return div_u64((u64)parent_rate * mult, 32);
+}
+
+static long cpg_z_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long *parent_rate)
+{
+	unsigned long prate  = *parent_rate;
+	unsigned int mult;
+
+	if (!prate)
+		prate = 1;
+
+	mult = div_u64((u64)rate * 32, prate);
+	mult = clamp(mult, 1U, 32U);
+
+	return *parent_rate / 32 * mult;
+}
+
+static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long parent_rate)
+{
+	struct cpg_z_clk *zclk = to_z_clk(hw);
+	unsigned int mult;
+	u32 val;
+
+	mult = div_u64((u64)rate * 32, parent_rate);
+	mult = clamp(mult, 1U, 32U);
+
+	val = clk_readl(zclk->reg);
+	val &= ~CPG_FRQCRC_ZFC_MASK;
+	val |= (32 - mult) << CPG_FRQCRC_ZFC_SHIFT;
+	clk_writel(val, zclk->reg);
+
+	return 0;
+}
+
+static const struct clk_ops cpg_z_clk_ops = {
+	.recalc_rate = cpg_z_clk_recalc_rate,
+	.round_rate = cpg_z_clk_round_rate,
+	.set_rate = cpg_z_clk_set_rate,
+};
+
+static struct clk * __init cpg_z_clk_register(struct rcar_gen2_cpg *cpg)
+{
+	static const char *parent_name = "pll0";
+	struct clk_init_data init;
+	struct cpg_z_clk *zclk;
+	struct clk *clk;
+
+	zclk = kzalloc(sizeof(*zclk), GFP_KERNEL);
+	if (!zclk)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = "z";
+	init.ops = &cpg_z_clk_ops;
+	init.flags = 0;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	zclk->reg = cpg->reg + CPG_FRQCRC;
+	zclk->hw.init = &init;
+
+	clk = clk_register(NULL, &zclk->hw);
+	if (IS_ERR(clk))
+		kfree(zclk);
+
+	return clk;
+}
+
+/* -----------------------------------------------------------------------------
+ * CPG Clock Data
+ */
+
+/*
+ *   MD		EXTAL		PLL0	PLL1	PLL3
+ * 14 13 19	(MHz)		*1	*1
+ *---------------------------------------------------
+ * 0  0  0	15 x 1		x172/2	x208/2	x106
+ * 0  0  1	15 x 1		x172/2	x208/2	x88
+ * 0  1  0	20 x 1		x130/2	x156/2	x80
+ * 0  1  1	20 x 1		x130/2	x156/2	x66
+ * 1  0  0	26 / 2		x200/2	x240/2	x122
+ * 1  0  1	26 / 2		x200/2	x240/2	x102
+ * 1  1  0	30 / 2		x172/2	x208/2	x106
+ * 1  1  1	30 / 2		x172/2	x208/2	x88
+ *
+ * *1 :	Table 7.6 indicates VCO ouput (PLLx = VCO/2)
+ */
+#define CPG_PLL_CONFIG_INDEX(md)	((((md) & BIT(14)) >> 12) | \
+					 (((md) & BIT(13)) >> 12) | \
+					 (((md) & BIT(19)) >> 19))
+struct cpg_pll_config {
+	unsigned int extal_div;
+	unsigned int pll1_mult;
+	unsigned int pll3_mult;
+};
+
+static const struct cpg_pll_config cpg_pll_configs[8] __initconst = {
+	{ 1, 208, 106 }, { 1, 208,  88 }, { 1, 156,  80 }, { 1, 156,  66 },
+	{ 2, 240, 122 }, { 2, 240, 102 }, { 2, 208, 106 }, { 2, 208,  88 },
+};
+
+/* SDHI divisors */
+static const struct clk_div_table cpg_sdh_div_table[] = {
+	{  0,  2 }, {  1,  3 }, {  2,  4 }, {  3,  6 },
+	{  4,  8 }, {  5, 12 }, {  6, 16 }, {  7, 18 },
+	{  8, 24 }, { 10, 36 }, { 11, 48 }, {  0,  0 },
+};
+
+static const struct clk_div_table cpg_sd01_div_table[] = {
+	{  5, 12 }, {  6, 16 }, {  7, 18 }, {  8, 24 },
+	{ 10, 36 }, { 11, 48 }, { 12, 10 }, {  0,  0 },
+};
+
+/* -----------------------------------------------------------------------------
+ * Initialization
+ */
+
+static u32 cpg_mode __initdata;
+
+static struct clk * __init
+rcar_gen2_cpg_register_clock(struct device_node *np, struct rcar_gen2_cpg *cpg,
+			     const struct cpg_pll_config *config,
+			     const char *name)
+{
+	const struct clk_div_table *table = NULL;
+	const char *parent_name = "main";
+	unsigned int shift;
+	unsigned int mult = 1;
+	unsigned int div = 1;
+
+	if (!strcmp(name, "main")) {
+		parent_name = of_clk_get_parent_name(np, 0);
+		div = config->extal_div;
+	} else if (!strcmp(name, "pll0")) {
+		/* PLL0 is a configurable multiplier clock. Register it as a
+		 * fixed factor clock for now as there's no generic multiplier
+		 * clock implementation and we currently have no need to change
+		 * the multiplier value.
+		 */
+		u32 value = clk_readl(cpg->reg + CPG_PLL0CR);
+		mult = ((value >> 24) & ((1 << 7) - 1)) + 1;
+	} else if (!strcmp(name, "pll1")) {
+		mult = config->pll1_mult / 2;
+	} else if (!strcmp(name, "pll3")) {
+		mult = config->pll3_mult;
+	} else if (!strcmp(name, "lb")) {
+		div = cpg_mode & BIT(18) ? 36 : 24;
+	} else if (!strcmp(name, "qspi")) {
+		div = (cpg_mode & (BIT(3) | BIT(2) | BIT(1))) == BIT(2)
+		    ? 16 : 20;
+	} else if (!strcmp(name, "sdh")) {
+		table = cpg_sdh_div_table;
+		shift = 8;
+	} else if (!strcmp(name, "sd0")) {
+		table = cpg_sd01_div_table;
+		shift = 4;
+	} else if (!strcmp(name, "sd1")) {
+		table = cpg_sd01_div_table;
+		shift = 0;
+	} else if (!strcmp(name, "z")) {
+		return cpg_z_clk_register(cpg);
+	} else {
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!table)
+		return clk_register_fixed_factor(NULL, name, parent_name, 0,
+						 mult, div);
+	else
+		return clk_register_divider_table(NULL, name, parent_name, 0,
+						 cpg->reg + CPG_SDCKCR, shift,
+						 4, 0, table, &cpg->lock);
+}
+
+static void __init rcar_gen2_cpg_clocks_init(struct device_node *np)
+{
+	const struct cpg_pll_config *config;
+	struct rcar_gen2_cpg *cpg;
+	struct clk **clks;
+	unsigned int i;
+	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(num_clks * 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.
+		 */
+		pr_err("%s: failed to allocate cpg\n", __func__);
+		return;
+	}
+
+	spin_lock_init(&cpg->lock);
+
+	cpg->data.clks = clks;
+	cpg->data.clk_num = num_clks;
+
+	cpg->reg = of_iomap(np, 0);
+	if (WARN_ON(cpg->reg == NULL))
+		return;
+
+	config = &cpg_pll_configs[CPG_PLL_CONFIG_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 = rcar_gen2_cpg_register_clock(np, cpg, config, 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(rcar_gen2_cpg_clks, "renesas,rcar-gen2-cpg-clocks",
+	       rcar_gen2_cpg_clocks_init);
+
+void __init rcar_gen2_clocks_init(u32 mode)
+{
+	cpg_mode = mode;
+
+	of_clk_init(NULL);
+}

include/linux/clk/shmobile.h

···
+/*
+ * Copyright 2013 Ideas On Board SPRL
+ *
+ * Contact: Laurent Pinchart <[e-mail]>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __LINUX_CLK_SHMOBILE_H_
+#define __LINUX_CLK_SHMOBILE_H_
+
+#include <linux/types.h>
+
+void rcar_gen2_clocks_init(u32 mode);
+
+#endif