[PATCH v7 04/05] clk: shmobile: Add Renesas R-Car Gen3 CPG support

[Magnus Damm <magnus.damm@gmail.com>]

From: Gaku Inami <gaku.inami.xw@bp.renesas.com>

This V7 patch adds initial CPG support for R-Car Generation 3 and in
particular the R8A7795 SoC.

The R-Car Gen3 clock hardware has a register write protection feature that
needs to be shared between the CPG function and the MSTP hardware somehow.
So far this feature is simply ignored.

Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
---

 Changes since V6: (Magnus Damm <damm+renesas@opensource.se>)
 - Moved PLL1 div-by-2 unit to outside of the CPG - thanks Laurent!
 - Updated table to reflect PLL1 divider move.
 - Reworked clock registration loop to prevent re-registering clocks.

Changes since V5: (Magnus Damm <damm+renesas@opensource.se>)
 - Removed unused spinlock, use 0x3f as mask - thanks Laurent!
 - Fixed space -> tab for DT binding documentation - thanks Geert!
 - Postponed PLL1 divide-by-2 rewrite - requires a tad more effort.
 - Updated commit log

 Changes since V4: (Magnus Damm <damm+renesas@opensource.se>)
 - Simplified clks array handling - thanks Geert!
 - Updated th DT binding documentation to reflect latest state
 - of_property_count_strings() -> of_property_count_u32_elems() fix

 Changes since V3: (Magnus Damm <damm+renesas@opensource.se>)
 - Reworked driver to incorporate most feedback from Stephen Boyd - thanks!!
 - Major things like syscon and driver model require more discussion.
 - Added hunk to build drivers/clk/shmobile if ARCH_RENESAS is set.

 Changes since V2: (Magnus Damm <damm+renesas@opensource.se>)
 - Reworked driver to rely on clock index instead of strings.
 - Dropped use of "clock-output-names".

 Earlier versions: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
 Initial version: Gaku Inami <gaku.inami.xw@bp.renesas.com>

 Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt |   32 +
 drivers/clk/Makefile                                                     |    1 
 drivers/clk/shmobile/Makefile                                            |    1 
 drivers/clk/shmobile/clk-rcar-gen3.c                                     |  242 ++++++++++
 4 files changed, 276 insertions(+)

--- /dev/null
+++ work/Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt	2015-09-07 20:43:37.672366518 +0900
@@ -0,0 +1,32 @@
+* Renesas R-Car Gen3 Clock Pulse Generator (CPG)
+
+The CPG generates core clocks for the R-Car Gen3 SoCs. It includes three PLLs
+and several fixed ratio dividers.
+
+Required Properties:
+
+  - compatible: Must be one of
+    - "renesas,r8a7795-cpg-clocks" for the r8a7795 CPG
+    - "renesas,rcar-gen3-cpg-clocks" for the generic R-Car Gen3 CPG
+
+  - reg: Base address and length of the memory resource used by the CPG
+
+  - clocks: References to the parent clocks: first to the EXTAL clock
+  - #clock-cells: Must be 1
+  - clock-indices: Indices of the exported clocks
+
+Example
+-------
+
+	cpg_clocks: cpg_clocks@e6150000 {
+		compatible = "renesas,r8a7795-cpg-clocks",
+			     "renesas,rcar-gen3-cpg-clocks";
+		reg = <0 0xe6150000 0 0x1000>;
+		clocks = <&extal_clk>;
+		#clock-cells = <1>;
+		clock-indices = <
+				R8A7795_CLK_MAIN R8A7795_CLK_PLL0
+				R8A7795_CLK_PLL1 R8A7795_CLK_PLL2
+				R8A7795_CLK_PLL3 R8A7795_CLK_PLL4
+		>;
+	};
--- 0014/drivers/clk/Makefile
+++ work/drivers/clk/Makefile	2015-09-07 20:43:36.642366518 +0900
@@ -67,6 +67,7 @@ obj-$(CONFIG_COMMON_CLK_QCOM)		+= qcom/
 obj-$(CONFIG_ARCH_ROCKCHIP)		+= rockchip/
 obj-$(CONFIG_COMMON_CLK_SAMSUNG)	+= samsung/
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= shmobile/
+obj-$(CONFIG_ARCH_RENESAS)		+= shmobile/
 obj-$(CONFIG_ARCH_SIRF)			+= sirf/
 obj-$(CONFIG_ARCH_SOCFPGA)		+= socfpga/
 obj-$(CONFIG_PLAT_SPEAR)		+= spear/
--- 0018/drivers/clk/shmobile/Makefile
+++ work/drivers/clk/shmobile/Makefile	2015-09-07 20:43:36.642366518 +0900
@@ -8,4 +8,5 @@ obj-$(CONFIG_ARCH_R8A7790)		+= clk-rcar-
 obj-$(CONFIG_ARCH_R8A7791)		+= clk-rcar-gen2.o clk-mstp.o clk-div6.o
 obj-$(CONFIG_ARCH_R8A7793)		+= clk-rcar-gen2.o clk-mstp.o clk-div6.o
 obj-$(CONFIG_ARCH_R8A7794)		+= clk-rcar-gen2.o clk-mstp.o clk-div6.o
+obj-$(CONFIG_ARCH_R8A7795)		+= clk-rcar-gen3.o clk-mstp.o clk-div6.o
 obj-$(CONFIG_ARCH_SH73A0)		+= clk-sh73a0.o clk-mstp.o clk-div6.o
--- /dev/null
+++ work/drivers/clk/shmobile/clk-rcar-gen3.c	2015-09-07 20:45:30.092366518 +0900
@@ -0,0 +1,242 @@
+/*
+ * rcar_gen3 Core CPG Clocks
+ *
+ * Copyright (C) 2015 Renesas Electronics Corp.
+ *
+ * Based on rcar_gen2 Core CPG Clocks driver.
+ *
+ * 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/clk/shmobile.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define RCAR_GEN3_CLK_MAIN	0
+#define RCAR_GEN3_CLK_PLL0	1
+#define RCAR_GEN3_CLK_PLL1	2
+#define RCAR_GEN3_CLK_PLL2	3
+#define RCAR_GEN3_CLK_PLL3	4
+#define RCAR_GEN3_CLK_PLL4	5
+#define RCAR_GEN3_CLK_NR	6
+
+static const char * const rcar_gen3_clk_names[RCAR_GEN3_CLK_NR] = {
+	[RCAR_GEN3_CLK_MAIN] = "main",
+	[RCAR_GEN3_CLK_PLL0] = "pll0",
+	[RCAR_GEN3_CLK_PLL1] = "pll1",
+	[RCAR_GEN3_CLK_PLL2] = "pll2",
+	[RCAR_GEN3_CLK_PLL3] = "pll3",
+	[RCAR_GEN3_CLK_PLL4] = "pll4",
+};
+
+struct rcar_gen3_cpg {
+	struct clk_onecell_data data;
+	void __iomem *reg;
+	struct clk *clks[RCAR_GEN3_CLK_NR];
+};
+
+#define CPG_PLL0CR	0x00d8
+#define CPG_PLL2CR	0x002c
+
+/*
+ * common function
+ */
+#define rcar_clk_readl(cpg, _reg) readl(cpg->reg + _reg)
+
+/*
+ * Reset register definitions.
+ */
+#define MODEMR 0xe6160060
+
+static u32 rcar_gen3_read_mode_pins(void)
+{
+	static u32 mode;
+	static bool mode_valid;
+
+	if (!mode_valid) {
+		void __iomem *modemr = ioremap_nocache(MODEMR, 4);
+
+		BUG_ON(!modemr);
+		mode = ioread32(modemr);
+		iounmap(modemr);
+		mode_valid = true;
+	}
+
+	return mode;
+}
+
+/* -----------------------------------------------------------------------------
+ * CPG Clock Data
+ */
+
+/*
+ *   MD		EXTAL		PLL0	PLL1	PLL2	PLL3	PLL4
+ * 14 13 19 17	(MHz)
+ *-------------------------------------------------------------------
+ * 0  0  0  0	16.66 x 1	x180	x192	x144	x192	x144
+ * 0  0  0  1	16.66 x 1	x180	x192	x144	x128	x144
+ * 0  0  1  0	Prohibited setting
+ * 0  0  1  1	16.66 x 1	x180	x192	x144	x192	x144
+ * 0  1  0  0	20    x 1	x150	x156	x120	x156	x120
+ * 0  1  0  1	20    x 1	x150	x156	x120	x106	x120
+ * 0  1  1  0	Prohibited setting
+ * 0  1  1  1	20    x 1	x150	x156	x120	x156	x120
+ * 1  0  0  0	25    x 1	x120	x128	x96	x128	x96
+ * 1  0  0  1	25    x 1	x120	x128	x96	x84	x96
+ * 1  0  1  0	Prohibited setting
+ * 1  0  1  1	25    x 1	x120	x128	x96	x128	x96
+ * 1  1  0  0	33.33 / 2	x180	x192	x144	x192	x144
+ * 1  1  0  1	33.33 / 2	x180	x192	x144	x128	x144
+ * 1  1  1  0	Prohibited setting
+ * 1  1  1  1	33.33 / 2	x180	x192	x144	x192	x144
+ */
+#define CPG_PLL_CONFIG_INDEX(md)	((((md) & BIT(14)) >> 11) | \
+					 (((md) & BIT(13)) >> 11) | \
+					 (((md) & BIT(19)) >> 18) | \
+					 (((md) & BIT(17)) >> 17))
+struct cpg_pll_config {
+	unsigned int extal_div;
+	unsigned int pll1_mult;
+	unsigned int pll3_mult;
+	unsigned int pll4_mult;
+};
+
+static const struct cpg_pll_config cpg_pll_configs[16] __initconst = {
+/* EXTAL div	PLL1	PLL3	PLL4 */
+	{ 1,	192,	192,	144, },
+	{ 1,	192,	128,	144, },
+	{ 0,	0,	0,	0,   }, /* Prohibited setting */
+	{ 1,	192,	192,	144, },
+	{ 1,	156,	156,	120, },
+	{ 1,	156,	106,	120, },
+	{ 0,	0,	0,	0,   }, /* Prohibited setting */
+	{ 1,	156,	156,	120, },
+	{ 1,	128,	128,	96,  },
+	{ 1,	128,	84,	96,  },
+	{ 0,	0,	0,	0,   }, /* Prohibited setting */
+	{ 1,	128,	128,	96,  },
+	{ 2,	192,	192,	144, },
+	{ 2,	192,	128,	144, },
+	{ 0,	0,	0,	0,   }, /* Prohibited setting */
+	{ 2,	192,	192,	144, },
+};
+
+/* -----------------------------------------------------------------------------
+ * Initialization
+ */
+
+static struct clk * __init
+rcar_gen3_cpg_register_clk(struct device_node *np, struct rcar_gen3_cpg *cpg,
+			   const struct cpg_pll_config *config,
+			   unsigned int gen3_clk)
+{
+	const char *parent_name = rcar_gen3_clk_names[RCAR_GEN3_CLK_MAIN];
+	unsigned int mult = 1;
+	unsigned int div = 1;
+	u32 value;
+
+	switch (gen3_clk) {
+	case RCAR_GEN3_CLK_MAIN:
+		parent_name = of_clk_get_parent_name(np, 0);
+		div = config->extal_div;
+		break;
+	case RCAR_GEN3_CLK_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.
+		 */
+		value = rcar_clk_readl(cpg, CPG_PLL0CR);
+		mult = ((value >> 24) & 0x3f) + 1;
+		break;
+	case RCAR_GEN3_CLK_PLL1:
+		mult = config->pll1_mult;
+		break;
+	case RCAR_GEN3_CLK_PLL2:
+		/* PLL2 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.
+		 */
+		value = rcar_clk_readl(cpg, CPG_PLL2CR);
+		mult = ((value >> 24) & 0x3f) + 1;
+		break;
+	case RCAR_GEN3_CLK_PLL3:
+		mult = config->pll3_mult;
+		break;
+	case RCAR_GEN3_CLK_PLL4:
+		mult = config->pll4_mult;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	return clk_register_fixed_factor(NULL, rcar_gen3_clk_names[gen3_clk],
+					 parent_name, 0, mult, div);
+}
+
+static void __init rcar_gen3_cpg_clocks_init(struct device_node *np)
+{
+	const struct cpg_pll_config *config;
+	struct rcar_gen3_cpg *cpg;
+	u32 cpg_mode;
+	unsigned int i;
+
+	cpg = kzalloc(sizeof(*cpg), GFP_KERNEL);
+	if (!cpg)
+		return;
+
+	cpg->reg = of_iomap(np, 0);
+	if (WARN_ON(cpg->reg == NULL))
+		return;
+
+	cpg_mode = rcar_gen3_read_mode_pins();
+
+	config = &cpg_pll_configs[CPG_PLL_CONFIG_INDEX(cpg_mode)];
+	if (!config->extal_div) {
+		pr_err("%s: Prohibited setting (cpg_mode=0x%x)\n",
+		       __func__, cpg_mode);
+		return;
+	}
+
+	for (i = 0; i < RCAR_GEN3_CLK_NR; ++i)
+		cpg->clks[i] = ERR_PTR(-ENOENT);
+
+	for (i = 0; i < RCAR_GEN3_CLK_NR; ++i) {
+		struct clk *clk;
+		u32 idx;
+		int ret;
+
+		ret = of_property_read_u32_index(np, "clock-indices", i, &idx);
+		if (ret < 0)
+			break;
+
+		if (idx >= RCAR_GEN3_CLK_NR) {
+			pr_err("%s: skipping unsupported %u\n", __func__, idx);
+		} else if (cpg->clks[idx] != ERR_PTR(-ENOENT)) {
+			pr_err("%s: skipping already registered %u\n",
+			       __func__, idx);
+		} else {
+			clk = rcar_gen3_cpg_register_clk(np, cpg, config, idx);
+
+			if (IS_ERR(clk))
+				pr_err("%s: unable to register %u (%ld)\n",
+				       __func__, idx, PTR_ERR(clk));
+			else
+				cpg->clks[idx] = clk;
+		}
+	}
+
+	cpg->data.clks = cpg->clks;
+	cpg->data.clk_num = i;
+
+	of_clk_add_provider(np, of_clk_src_onecell_get, &cpg->data);
+}
+CLK_OF_DECLARE(rcar_gen3_cpg_clks, "renesas,rcar-gen3-cpg-clocks",
+	       rcar_gen3_cpg_clocks_init);