Re: [PATCH/RFC 1/1] soc: renesas: Add DT fixup code for missing r8a7791 RST

[Pantelis Antoniou]

Hi Geert,

A few notes.

> On Jun 1, 2016, at 22:50 , Geert Uytterhoeven <geert+renesas@xxxxxxxxx> wrote:
> 
> Add DT fixup code to add a reset-controller node for the r8a7791 RST
> module if it's not yet present.
> 
> This allows the R-Car Gen2 clock driver to use the RST driver to obtain
> the value of the mode pins, instead of reading from a hardcoded address
> in rcar_gen2_read_mode_pins(), while providing backward compatibility
> with old DTBs.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> ---
> drivers/soc/renesas/Makefile           |   4 +
> drivers/soc/renesas/renesas-dt-fixup.c | 159 +++++++++++++++++++++++++++++++++
> 2 files changed, 163 insertions(+)
> create mode 100644 drivers/soc/renesas/renesas-dt-fixup.c
> 
> diff --git a/drivers/soc/renesas/Makefile b/drivers/soc/renesas/Makefile
> index 0d732ff893dd8fba..e5f4454821ca6f63 100644
> --- a/drivers/soc/renesas/Makefile
> +++ b/drivers/soc/renesas/Makefile
> @@ -1,3 +1,7 @@
> +# FIXME Depend on new Kconfig symbol CONFIG_ARCH_RENESAS_LEGACY
> +# FIXME Needs OF_DYNAMIC
> +obj-$(CONFIG_ARCH_RENESAS)	+= renesas-dt-fixup.o
> +
> obj-$(CONFIG_ARCH_RCAR_GEN1)	+= rcar-rst.o
> obj-$(CONFIG_ARCH_RCAR_GEN2)	+= rcar-rst.o
> obj-$(CONFIG_ARCH_R8A7795)	+= rcar-rst.o
> diff --git a/drivers/soc/renesas/renesas-dt-fixup.c b/drivers/soc/renesas/renesas-dt-fixup.c
> new file mode 100644
> index 0000000000000000..83c9ca6b44f8136c
> --- /dev/null
> +++ b/drivers/soc/renesas/renesas-dt-fixup.c
> @@ -0,0 +1,159 @@
> +/*
> + * Renesas DT Fixup Code
> + *
> + * Provide backwards compatibility with old DTBs by updating the DT
> + *
> + * Copyright (C) 2016 Glider bvba
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +
> +#define RST_BASE	0xe6160000
> +#define RST_SIZE	0x0100		/* R-Car Gen2 */
> +
> +static struct property rst_compatible = {
> +	.name = "compatible",
> +};
> +
> +static __be32 rst_reg_values[4] = {
> +	cpu_to_be32(0),
> +	cpu_to_be32(RST_BASE),
> +	cpu_to_be32(0),
> +	cpu_to_be32(RST_SIZE),
> +};
> +
> +static struct property rst_name = {
> +	.name = "name",
> +	.length = sizeof("reset-controller"),
> +	.value = "reset-controller",
> +};
> +
> +static struct property rst_reg = {
> +	.name = "reg",
> +	.length = sizeof(rst_reg_values),
> +	.value = rst_reg_values,
> +};
> +
> +static int __init add_rst(struct device_node *parent, const char *path,
> +			  char *compatible)
> +{
> +	struct property *prop[] = { &rst_compatible, &rst_name, &rst_reg };
> +	struct device_node *np;
> +	char *full_name;
> +	unsigned int i;
> +	int error;
> +
> +	pr_debug("Adding RST node %s\n", compatible);
> +	np = kzalloc(sizeof(*np), GFP_KERNEL);
> +	if (!np)
> +		return -ENOMEM;
> +
> +	np->name = kasprintf(GFP_KERNEL, "%s@%x", (char *)rst_name.value,
> +			     RST_BASE);
> +	full_name = kasprintf(GFP_KERNEL, "%s/%s", path, np->name);
> +	np->full_name = full_name;
> +	np->parent = parent;
> +
> +	of_node_set_flag(np, OF_DYNAMIC);
> +	of_node_init(np);
> +
> +	error = of_attach_node(np);
> +	if (error) {
> +		pr_err("%s: of_attach_node() %s failed %d\n", __func__,
> +		       np->name, error);
> +		kfree(np);
> +		return error;
> +	}
> +
> +	rst_compatible.value = compatible;
> +	rst_compatible.length = strlen(rst_compatible.value) + 1;
> +
> +	for (i = 0; i < ARRAY_SIZE(prop); i++) {
> +		error = of_add_property(np, prop[i]);
> +		if (error)
> +			pr_err("%s: of_add_property() %s/%s failed %d\n",
> +			       __func__, np->name, prop[i]->name, error);
> +	}
> +
> +	return 0;
> +}
> +

Using changesets (especially with the new changeset helpers would make this
so much simpler. Or you could compile in a DTBO that performs the changes
although you will have to tweak it since it appears youâre not using fixed
names and properties all the way.

> +static int __init add_sysc(struct device_node *parent, const char *path,
> +			   char *compatible)
> +{
> +	pr_debug("NOT YET adding SYSC node %s\n", compatible);
> +	return 0;
> +}
> +
> +static const struct of_device_id renesas_matches[] __initconst = {
> +	{ .compatible = "renesas,r8a7791", },
> +	{ /* sentinel */ }
> +};
> +
> +static int __init renesas_dt_fixup(void)
> +{
> +	const struct of_device_id *match;
> +	struct device_node *np, *parent;
> +	const char *parent_path;
> +	char *compatible;
> +
> +	np = of_find_node_by_path("/");
> +	if (!np)
> +		return -ENODEV;
> +
> +	for (match = renesas_matches; match->compatible[0]; match++)
> +		if (of_device_is_compatible(np, match->compatible))
> +			break;
> +	of_node_put(np);
> +
> +	if (!match->compatible[0])
> +		return -ENODEV;
> +
> +	/* Find the main SoC bus node */
> +	np = of_find_compatible_node(NULL, NULL, "arm,gic-400");
> +	if (!np) {
> +		pr_warn("%s: Cannot find %s\n", __func__, "arm,gic-400");
> +		return -ENODEV;
> +	}
> +
> +	parent = of_get_parent(np);
> +	of_node_put(np);
> +	if (!parent) {
> +		pr_warn("%s: Cannot find GIC parent\n", __func__);
> +		return -ENODEV;
> +	}
> +
> +	parent_path = parent->full_name;
> +	/* Prevent double leading slash */
> +	if (!parent_path[1])
> +		parent_path++;
> +
> +	compatible = kasprintf(GFP_KERNEL, "%s-rst", match->compatible);
> +	if (of_find_compatible_node(NULL, NULL, compatible)) {
> +		pr_debug("%s: RST node %s present\n", __func__, compatible);
> +		kfree(compatible);
> +	} else {
> +		add_rst(parent, parent_path, compatible);
> +	}
> +
> +	compatible = kasprintf(GFP_KERNEL, "%s-sysc", match->compatible);
> +	if (of_find_compatible_node(NULL, NULL, compatible)) {
> +		pr_debug("%s: SYSC node %s present\n", __func__, compatible);
> +		kfree(compatible);
> +	} else {
> +		add_sysc(parent, parent_path, compatible);
> +	}
> +
> +	of_node_put(parent);
> +	return 0;
> +}
> +early_initcall(renesas_dt_fixup);
> -- 
> 1.9.1
> 

Regards

â Pantelis