[PATCH 0/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[PATCH 0/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[Kuninori Morimoto]

Hi Stephen, Michael
Cc: Simon, Magnus, Geert

These are Renesas R-Car Gen3 clock support patches.
We need incremental update for it, but it is good enough for initial booting.
Renesas R-Car Gen3 initial SoC/board support patch-set depends on these patches.

Renesas SoC series maintainer is Simon and Magnus.
Simon can accept (?) these patches as part of Renesas SoC if Stephen / Michael
can give it Ack. Or Simon can merge Stephen or Michael's branch.
I'm not sure which one is good choice

Gaku Inami (1):
      clk: shmobile: add Renesas R-Car Gen3 CPG support

Kuninori Morimoto (1):
      clk: shmobile: Add r8a7795 SoC to MSTP bindings

 Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt      |   1 +
 Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt |  31 ++++++++++++
 drivers/clk/shmobile/Makefile                                            |   1 +
 drivers/clk/shmobile/clk-rcar-gen3.c                                     | 232 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 265 insertions(+)

[PATCH 1/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[Kuninori Morimoto]

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

This patch adds very initial CPG support.
R-Car Gen3 write function should use CPG write protection method
which is shared with MSTP driver. This patch has it but not used.

Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
---
 .../clock/renesas,rcar-gen3-cpg-clocks.txt         |  31 +++
 drivers/clk/shmobile/Makefile                      |   1 +
 drivers/clk/shmobile/clk-rcar-gen3.c               | 232 +++++++++++++++++++++
 3 files changed, 264 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt
 create mode 100644 drivers/clk/shmobile/clk-rcar-gen3.c

diff --git a/Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt b/Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt
new file mode 100644
index 0000000..b1a7e01
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/renesas,rcar-gen3-cpg-clocks.txt
@@ -0,0 +1,31 @@
+* 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-output-names: The names of the clocks. Supported clocks are
+    "main", "pll0", "pll1", "pll2", "pll3", "pll4"
+
+
+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-output-names = "main", "pll0", "pll1","pll2",
+				     "pll3", "pll4";
+	};
diff --git a/drivers/clk/shmobile/Makefile b/drivers/clk/shmobile/Makefile
index 97c71c8..4e70a73 100644
--- a/drivers/clk/shmobile/Makefile
+++ b/drivers/clk/shmobile/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_ARCH_R8A7790)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_R8A7791)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_R8A7793)		+= clk-rcar-gen2.o
 obj-$(CONFIG_ARCH_R8A7794)		+= clk-rcar-gen2.o
+obj-$(CONFIG_ARCH_RCAR_GEN3)		+= clk-rcar-gen3.o
 obj-$(CONFIG_ARCH_SH73A0)		+= clk-sh73a0.o
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= clk-div6.o
 obj-$(CONFIG_ARCH_SHMOBILE_MULTI)	+= clk-mstp.o
diff --git a/drivers/clk/shmobile/clk-rcar-gen3.c b/drivers/clk/shmobile/clk-rcar-gen3.c
new file mode 100644
index 0000000..098caac
--- /dev/null
+++ b/drivers/clk/shmobile/clk-rcar-gen3.c
@@ -0,0 +1,232 @@
+/*
+ * 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/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_gen3_cpg {
+	struct clk_onecell_data data;
+	spinlock_t lock;
+	void __iomem *reg;
+};
+
+#define CPG_PLL0CR	0x00d8
+#define CPG_PLL2CR	0x002c
+
+/*
+ * common function
+ */
+#define rcar_clk_readl(cpg, _reg) clk_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)		*1	*1	*1
+ *-------------------------------------------------------------------
+ * 0  0  0  0	16.66 x 1	x180/2	x192/2	x144/2	x192	x144
+ * 0  0  0  1	16.66 x 1	x180/2	x192/2	x144/2	x128	x144
+ * 0  0  1  0	Prohibited setting
+ * 0  0  1  1	16.66 x 1	x180/2	x192/2	x144/2	x192	x144
+ * 0  1  0  0	20    x 1	x150/2	x156/2	x120/2	x156	x120
+ * 0  1  0  1	20    x 1	x150/2	x156/2	x120/2	x106	x120
+ * 0  1  1  0	Prohibited setting
+ * 0  1  1  1	20    x 1	x150/2	x156/2	x120/2	x156	x120
+ * 1  0  0  0	25    x 1	x120/2	x128/2	x96/2	x128	x96
+ * 1  0  0  1	25    x 1	x120/2	x128/2	x96/2	x84	x96
+ * 1  0  1  0	Prohibited setting
+ * 1  0  1  1	25    x 1	x120/2	x128/2	x96/2	x128	x96
+ * 1  1  0  0	33.33 / 2	x180/2	x192/2	x144/2	x192	x144
+ * 1  1  0  1	33.33 / 2	x180/2	x192/2	x144/2	x128	x144
+ * 1  1  1  0	Prohibited setting
+ * 1  1  1  1	33.33 / 2	x180/2	x192/2	x144/2	x192	x144
+ *
+ * *1 : datasheet indicates VCO output (PLLx = VCO/2)
+ *
+ */
+#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 u32 cpg_mode __initdata;
+
+static struct clk * __init
+rcar_gen3_cpg_register_clock(struct device_node *np, struct rcar_gen3_cpg *cpg,
+			     const struct cpg_pll_config *config,
+			     const char *name)
+{
+	const char *parent_name;
+	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 = rcar_clk_readl(cpg, CPG_PLL0CR);
+
+		parent_name = "main";
+		mult = ((value >> 24) & ((1 << 7) - 1)) + 1;
+	} else if (!strcmp(name, "pll1")) {
+		parent_name = "main";
+		mult = config->pll1_mult / 2;
+	} else if (!strcmp(name, "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.
+		 */
+		u32 value = rcar_clk_readl(cpg, CPG_PLL2CR);
+
+		parent_name = "main";
+		mult = ((value >> 24) & ((1 << 7) - 1)) + 1;
+	} else if (!strcmp(name, "pll3")) {
+		parent_name = "main";
+		mult = config->pll3_mult;
+	} else if (!strcmp(name, "pll4")) {
+		parent_name = "main";
+		mult = config->pll4_mult;
+	} else {
+		return ERR_PTR(-EINVAL);
+	}
+
+	return clk_register_fixed_factor(NULL, name, 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;
+	struct clk **clks;
+	unsigned int i;
+	int num_clks;
+
+	cpg_mode = rcar_gen3_read_mode_pins();
+
+	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)];
+	if (!config->extal_div) {
+		pr_err("%s: Prohibited setting (cpg_mode=0x%x)\n",
+		       __func__, cpg_mode);
+		return;
+	}
+
+	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_gen3_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_gen3_cpg_clks, "renesas,rcar-gen3-cpg-clocks",
+	       rcar_gen3_cpg_clocks_init);
-- 
1.9.1

[PATCH 2/2] clk: shmobile: Add r8a7795 SoC to MSTP bindings

[Kuninori Morimoto]

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
---
 Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt b/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
index 16ed181..4169c76 100644
--- a/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
+++ b/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
@@ -19,6 +19,7 @@ Required Properties:
     - "renesas,r8a7791-mstp-clocks" for R8A7791 (R-Car M2-W) MSTP gate clocks
     - "renesas,r8a7793-mstp-clocks" for R8A7793 (R-Car M2-N) MSTP gate clocks
     - "renesas,r8a7794-mstp-clocks" for R8A7794 (R-Car E2) MSTP gate clocks
+    - "renesas,r8a7795-mstp-clocks" for R8A7795 (R-Car H3) MSTP gate clocks
     - "renesas,sh73a0-mstp-clocks" for SH73A0 (SH-MobileAG5) MSTP gate clocks
     and "renesas,cpg-mstp-clocks" as a fallback.
   - reg: Base address and length of the I/O mapped registers used by the MSTP
-- 
1.9.1

Re: [PATCH 1/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[Stephen Boyd]

On 08/25, Kuninori Morimoto wrote:
> diff --git a/drivers/clk/shmobile/clk-rcar-gen3.c b/drivers/clk/shmobile/clk-rcar-gen3.c
> new file mode 100644
> index 0000000..098caac
> --- /dev/null
> +++ b/drivers/clk/shmobile/clk-rcar-gen3.c
> @@ -0,0 +1,232 @@
> +/*
> + * 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/clkdev.h>

Is this include used?

> +#include <linux/clk/shmobile.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/math64.h>

Is this include used?

> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/spinlock.h>
> +
> +struct rcar_gen3_cpg {
> +	struct clk_onecell_data data;
> +	spinlock_t lock;
> +	void __iomem *reg;
> +};
> +
> +#define CPG_PLL0CR	0x00d8
> +#define CPG_PLL2CR	0x002c
> +
> +/*
> + * common function
> + */
> +#define rcar_clk_readl(cpg, _reg) clk_readl(cpg->reg + _reg)

Please just use readl instead of clk_readl.

> +
> +/*
> + * 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;
> +}

Perhaps this should be read using a syscon?

> +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 = {

We don't actually need the 16, but ok.

> +/* 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 u32 cpg_mode __initdata;

Why isn't this local to the only function that uses it?

> +
> +static void __init rcar_gen3_cpg_clocks_init(struct device_node *np)
> +{
> +	const struct cpg_pll_config *config;
> +	struct rcar_gen3_cpg *cpg;
> +	struct clk **clks;
> +	unsigned int i;
> +	int num_clks;
> +
> +	cpg_mode = rcar_gen3_read_mode_pins();
> +
> +	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);

kcalloc()

> +	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.
> +		 */

kfree() does nothing on NULL, so it should be easy enough to
delete this comment and replace it with two calls to kfree().

> +		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)];
> +	if (!config->extal_div) {
> +		pr_err("%s: Prohibited setting (cpg_mode=0x%x)\n",
> +		       __func__, cpg_mode);
> +		return;
> +	}
> +
> +	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_gen3_cpg_register_clock(np, cpg, config, name);

Is there any reason why we need to register clocks based on
what's in DT? I would prefer to see a method where we register
clocks based on the compatible string in DT. This would get rid
of all the string comparisons in rcar_gen3_cpg_register_clock()
and make for cleaner code.

Furthermore, we could make this into a platform driver so that we
can benefit from the device model.

> +		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_gen3_cpg_clks, "renesas,rcar-gen3-cpg-clocks",
> +	       rcar_gen3_cpg_clocks_init);

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH 1/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[Geert Uytterhoeven]

Hi Stephen,

On Wed, Aug 26, 2015 at 12:46 AM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> --- /dev/null
>> +++ b/drivers/clk/shmobile/clk-rcar-gen3.c

>> +
>> +/*
>> + * 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;
>> +}
>
> Perhaps this should be read using a syscon?

Like "[PATCH/RFC 00/11] ARM: shmobile: Let CPG use syscon for MD pin values"
(http://www.spinics.net/lists/linux-clk/msg01478.html)?

It wasn't so well received...

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 1/2] clk: shmobile: add Renesas R-Car Gen3 CPG support

[Magnus Damm]

Hi Geert,

On Wed, Aug 26, 2015 at 4:29 PM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> Hi Stephen,
>
> On Wed, Aug 26, 2015 at 12:46 AM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>> --- /dev/null
>>> +++ b/drivers/clk/shmobile/clk-rcar-gen3.c
>
>>> +
>>> +/*
>>> + * 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;
>>> +}
>>
>> Perhaps this should be read using a syscon?
>
> Like "[PATCH/RFC 00/11] ARM: shmobile: Let CPG use syscon for MD pin values"
> (http://www.spinics.net/lists/linux-clk/msg01478.html)?
>
> It wasn't so well received...

I happen to think it is a great idea. At the same time I'm too lazy to
step up. =)

Shall we reconsider making it mandatory for R-Car Gen3?

Cheers,

/ magnus