Re: [PATCH V2 01/12] clk: shmobile: add CPG driver for rz-platforms

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Wolfram,

Thank you for the patch.

On Thursday 06 March 2014 12:32:21 Wolfram Sang wrote:
> From: Wolfram Sang <wsa@sang-engineering.com>
> 
> Signed-off-by: Wolfram Sang <wsa@sang-engineering.com>
> ---
> 
> Changes since V1:
> * added docs
> * preparation for usb_x1 support by documenting two input clocks
> * static-consted frqcr_tab
> * bail out if num_clks = 0
> * cosmetic fixes
> 
> Mike: if you are fine with this driver, it would be good if you could apply
> it. Then, we can deal with the orthogonal dependencies in mach-shmobile
> seperately and know that the driver is already in place when the rest gets
> resolved. Thanks!
> 
>  .../bindings/clock/renesas,rz-cpg-clocks.txt       |  29 ++++++
>  drivers/clk/shmobile/Makefile                      |   1 +
>  drivers/clk/shmobile/clk-rz.c                      | 113 ++++++++++++++++++
>  3 files changed, 143 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/clock/renesas,rz-cpg-clocks.txt create
> mode 100644 drivers/clk/shmobile/clk-rz.c
> 
> diff --git
> a/Documentation/devicetree/bindings/clock/renesas,rz-cpg-clocks.txt
> b/Documentation/devicetree/bindings/clock/renesas,rz-cpg-clocks.txt new
> file mode 100644
> index 000000000000..c8e8821f08f6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/renesas,rz-cpg-clocks.txt
> @@ -0,0 +1,29 @@
> +* Renesas RZ Clock Pulse Generator (CPG)
> +
> +The CPG generates core clocks for the RZ SoCs. It includes the PLL,
> variable +CPU and GPU clocks, and several fixed ratio dividers.
> +
> +Required Properties:
> +
> +  - compatible: Must be one of
> +    - "renesas,r7s72100-cpg-clocks" for the r7s72100 CPG
> +    - "renesas,rz-cpg-clocks" for the generic RZ CPG
> +  - reg: Base address and length of the memory resource used by the CPG
> +  - clocks: References to possible parent clocks. Order must match clock
> modes
> +    in the datasheet.

I believe the order should be documented explicitly instead of referring to 
the datasheet.

> +  - #clock-cells: Must be 1
> +  - clock-output-names: The names of the clocks. Supported clocks are
> "pll",
> +    "i", and "g"
> +
> +
> +Example
> +-------
> +
> +	cpg_clocks: cpg_clocks@fcfe0000 {
> +		#clock-cells = <1>;
> +		compatible = "renesas,r7s72100-cpg-clocks",
> +			     "renesas,rz-cpg-clocks";
> +		reg = <0xfcfe0000 0x18>;
> +		clocks = <&extal_clk>, <&usb_x1_clk>;
> +		clock-output-names = "pll", "i", "g";
> +	};
> diff --git a/drivers/clk/shmobile/Makefile b/drivers/clk/shmobile/Makefile
> index 9ecef140dba7..5404cb931ebf 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_R7S72100)		+= clk-rz.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-rz.c b/drivers/clk/shmobile/clk-rz.c
> new file mode 100644
> index 000000000000..2901db3ac5d3
> --- /dev/null
> +++ b/drivers/clk/shmobile/clk-rz.c
> @@ -0,0 +1,113 @@
> +/*
> + * rz Core CPG Clocks
> + *
> + * Copyright (C) 2013 Ideas On Board SPRL
> + * Copyright (C) 2014 Wolfram Sang, Sang Engineering
> <wsa@sang-engineering.com> + *
> + * 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/init.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>
> +
> +struct rz_cpg {
> +	struct clk_onecell_data data;
> +	void __iomem *reg;
> +};
> +
> +#define CPG_FRQCR	0x10
> +#define CPG_FRQCR2	0x14
> +
> +/*
> ---------------------------------------------------------------------------
> -- + * Initialization
> + */
> +
> +static struct clk * __init
> +rz_cpg_register_clock(struct device_node *np, struct rz_cpg *cpg, const
> char *name)
> +{
> +	u32 val;
> +	unsigned mult;
> +	static const unsigned frqcr_tab[4] = { 3, 2, 0, 1 };
> +
> +	if (strcmp(name, "pll") = 0) {
> +		/* FIXME: cpg_mode should be read from GPIO. But no GPIO support yet
> */
> +		unsigned cpg_mode = 0; /* hardcoded to EXTAL for now */
> +		const char *parent_name = of_clk_get_parent_name(np, cpg_mode);
> +
> +		mult = cpg_mode ? (32 / 4) : 30;
> +
> +		return clk_register_fixed_factor(NULL, name, parent_name, 0, mult,
> 1);
> +	}
> +
> +	/* FIXME:"i" and "g" are variable clocks with non-integer dividers (e.g.
> 2/3)
> +	 * and the constraint that always g <= i. To get the rz platform started,
> +	 * let them run at fixed current speed and implement the details later.
> +	 */
> +	if (strcmp(name, "i") = 0)
> +		val = (clk_readl(cpg->reg + CPG_FRQCR) >> 8) & 3;
> +	else if (strcmp(name, "g") = 0)
> +		val = clk_readl(cpg->reg + CPG_FRQCR2) & 3;
> +	else
> +		return ERR_PTR(-EINVAL);
> +
> +	mult = frqcr_tab[val];
> +	return clk_register_fixed_factor(NULL, name, "pll", 0, mult, 3);
> +}
> +
> +static void __init rz_cpg_clocks_init(struct device_node *np)
> +{
> +	struct rz_cpg *cpg;
> +	struct clk **clks;
> +	unsigned i;
> +	int num_clks;
> +
> +	num_clks = of_property_count_strings(np, "clock-output-names");
> +	if (WARN(num_clks <= 0, "can't count CPG clocks\n"))
> +		goto out;

You can return directly instead of goto out.

> +
> +	cpg = kzalloc(sizeof(*cpg), GFP_KERNEL);
> +	if (WARN(!cpg, "out of memory!\n"))

kmalloc() warns already when it can't allocate memory, so you can remove the 
warning here.

> +		goto out;

You can return directly here too.

> +
> +	clks = kzalloc(num_clks * sizeof(*clks), GFP_KERNEL);
> +	if (WARN(!clks, "out of memory!\n"))

You can remove this warning too.

> +		goto free_cpg;
> +
> +	cpg->data.clks = clks;
> +	cpg->data.clk_num = num_clks;
> +
> +	cpg->reg = of_iomap(np, 0);
> +	if (WARN(!cpg->reg, "can't remap CPG registers!\n"))
> +		goto free_clks;
> +
> +	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 = rz_cpg_register_clock(np, cpg, 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);
> +	return;
> +
> +free_clks:
> +	kfree(clks);
> +free_cpg:
> +	kfree(cpg);
> +out:
> +	return;

No need for an explicit return.

> +}
> +CLK_OF_DECLARE(rz_cpg_clks, "renesas,rz-cpg-clocks", rz_cpg_clocks_init);

-- 
Regards,

Laurent Pinchart