Subject: [PATCH v3 01/20] clk: shmobile: r8a7779: Add clocks support

From: [email-masked] (Laurent Pinchart)
Date: Wed, 26 Feb 2014 14:02:37 +0100

Hi Simon,

Two more small comments.

On Wednesday 26 February 2014 13:53:17 Laurent Pinchart wrote:
> On Wednesday 26 February 2014 16:33:17 Simon Horman wrote:
> > The R8A7779 SoC has 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.
> 
> Looking at the R8A7779 datasheet it looks like we only have fixed rate
> clocks, without any configurable divider clock. Did I miss something ?
> 
> > Based on work for R-Car Gen2 SoCs by Laurent Pinchart.
> > 
> > Cc: Laurent Pinchart <[email-masked]>
> > Signed-off-by: Simon Horman <[email-masked]>
> > 
> > ---
> > v3
> > * As suggested by Laurent Pinchart
> > 
> >   - Added external clock input
> >   - Use PLLA ratio set bu MD11 and MD12
> >   - Add _div suffixes of fields of struct cpt_clk_config
> >   - Register PLLA as a fixed factor clock
> >   - Use sizeof() instead of sizeof
> >   - Use num_clks instead of CPG_NUM_CLOCKS in r8a7779_cpg_clocks_init()
> >   
> >   - I kept this as r8a7779 binding rather than moving to a R-Car Gen1
> >   
> >     binding which could be shared with other SoCs as I do not believe that
> >     the SoCs is are sufficiently similar.
> 
> I had a look at the M1 datasheet and I still find its CPG very similar with
> the H1 CPG. The PLLA multiplier and divider are different, but if you look
> closely, they're both exactly twice the value compared to H1, so there's no
> difference in practice.
> 
> What differences do you see that would make it impractical to share a single
> driver for both ?
> 
> > ---
> > 
> >  .../bindings/clock/renesas,r8a7779-cpg-clocks.txt  |  26 +++
> >  drivers/clk/shmobile/Makefile                      |   1 +
> >  drivers/clk/shmobile/clk-r8a7779.c                 | 191
> >  ++++++++++++++++++
> >  include/linux/clk/shmobile.h                       |   3 +
> >  4 files changed, 221 insertions(+)
> >  create mode 100644
> > 
> > Documentation/devicetree/bindings/clock/renesas,r8a7779-cpg-clocks.txt
> > create mode 100644 drivers/clk/shmobile/clk-r8a7779.c
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/clock/renesas,r8a7779-cpg-clocks.txt
> > b/Documentation/devicetree/bindings/clock/renesas,r8a7779-cpg-clocks.txt
> > new file mode 100644
> > index 0000000..1461323
> > --- /dev/null
> > +++
> > b/Documentation/devicetree/bindings/clock/renesas,r8a7779-cpg-clocks.txt
> > @@ -0,0 +1,26 @@
> > +* Renesas R8A7779 Clock Pulse Generator (CPG)
> > +
> > +The CPG generates core clocks for the R8A7779. It includes one PLL and
> > +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", "out".
> 
> What about clki, clks3, clks4, clkb and clkg ? Should pllb be exposed as
> well ?

I spoke too fast, clki, clks3, clks4 and clkg are fixed factor clocks 
expressed in DT, my bad. What about clkb though ?

> 
> > +Example
> > +-------
> > +
> > +	cpg_clocks: cpg_clocks at ffc80000 {
> > +		compatible = "renesas,r8a7779-cpg-clocks";
> > +		reg = <0 0xffc80000 0 0x80>;
> 
> Shouldn't the range be restricted not to include the MSTP registers ? 0x30
> should be enough.
> 
> > +		clocks = <&extal_clk>;
> > +		#clock-cells = <1>;
> > +		clock-output-names = "plla", "z", "zs", "s", "s1", "p", "out";
> > +	};
> > diff --git a/drivers/clk/shmobile/Makefile b/drivers/clk/shmobile/Makefile
> > index 9ecef14..2121ba0 100644
> > --- a/drivers/clk/shmobile/Makefile
> > +++ b/drivers/clk/shmobile/Makefile
> > @@ -1,4 +1,5 @@
> > 
> >  obj-$(CONFIG_ARCH_EMEV2)		+= clk-emev2.o
> > 
> > +obj-$(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
> > 
> > diff --git a/drivers/clk/shmobile/clk-r8a7779.c
> > b/drivers/clk/shmobile/clk-r8a7779.c new file mode 100644
> > index 0000000..2ca2d67
> > --- /dev/null
> > +++ b/drivers/clk/shmobile/clk-r8a7779.c
> > @@ -0,0 +1,191 @@
> > +/*
> > + * r8a7779 Core CPG Clocks
> > + *
> > + * Copyright (C) 2013, 2014 Horms Solutions Ltd.
> > + *
> > + * Contact: Simon Horman <[email-masked]>
> > + *
> > + * 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(1)|BIT(2))) >> 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 out_div;
> > +};
> > +
> > +static const struct cpg_clk_config cpg_clk_configs[4] __initconst = {
> > +	{ 1, 2, 8, 16, 32, 24 },
> > +	{ 1, 2, 8, 16, 32, 24 },
> > +	{ 2, 3, 6, 12, 24, 36 },
> > +	{ 2, 3, 6, 12, 24, 32 },
> > +};
> > +
> > +/*
> > + *   MD		PLLA Ratio
> > + * 12 11
> > + *------------------------
> > + * 0  0		x42
> > + * 0  1		x48
> > + * 1  0		x56
> > + * 1  1		x64
> > + */
> > +#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;
> > +};
> > +
> > +#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, "out")) {
> > +		div = config->out_div;
> > +	}
> 
> You're missing an
> 
> 	else {
> 		return ERR_PTR5-EINVAL);
> 	}
> 
> I was tempted to say that it would make sense to read the div values from
> the FRQMR register instead and remove the need to pass the boot mode bits
> to the driver, but we need them for the PLLA multiplier anyway :-/
> 
> > +
> > +	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.
> > +		 */
> > +		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;

As the driver doesn't access any of the CPG registers this could even be 
removed.

> > +
> > +	config = &cpg_clk_configs[CPG_CLK_CONFIG_INDEX(cpg_mode)];
> > +	plla_mult = cpg_plla_mult[CPG_PLLA_MULT_INDEX(cpg_mode)];
> 
> Given that plla_mult is only used for a single clock, I would move that
> inside the if (!strcmp(name, "plla")) { } above.
> 
> > +
> > +	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);
> > +}
> > diff --git a/include/linux/clk/shmobile.h b/include/linux/clk/shmobile.h
> > index f9bf080..7667f49 100644
> > --- a/include/linux/clk/shmobile.h
> > +++ b/include/linux/clk/shmobile.h
> > @@ -1,7 +1,9 @@
> >  /*
> >   * Copyright 2013 Ideas On Board SPRL
> > + * Copyright 2013 Horms Solutions Ltd.
> 
> 2014 ?
> 
> >   *
> >   * Contact: Laurent Pinchart <[email-masked]>
> > + * Contact: Simon Horman <[email-masked]>
> >   *
> >   * 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

-- 
Regards,

Laurent Pinchart