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Message-ID: <20130718095035.GA29153@e106331-lin.cambridge.arm.com>
Date: Thu, 18 Jul 2013 10:50:35 +0100
From: Mark Rutland <mark.rutland@....com>
To: Jonas Jensen <jonas.jensen@...il.com>
Cc: "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"arm@...nel.org" <arm@...nel.org>,
"mturquette@...aro.org" <mturquette@...aro.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] clk: add MOXA ART SoCs clock driver
On Wed, Jul 17, 2013 at 02:23:16PM +0100, Jonas Jensen wrote:
> This patch adds MOXA ART SoCs clock driver support.
>
> Signed-off-by: Jonas Jensen <jonas.jensen@...il.com>
> ---
>
> Notes:
> Changes since v2:
>
> 1. add devicetree bindings document
>
> Applies to next-20130716
>
> .../bindings/clock/moxa,moxart-core-clock.txt | 19 +++++
> drivers/clk/Makefile | 1 +
> drivers/clk/clk-moxart.c | 82 ++++++++++++++++++++++
> 3 files changed, 102 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/moxa,moxart-core-clock.txt
> create mode 100644 drivers/clk/clk-moxart.c
>
> diff --git a/Documentation/devicetree/bindings/clock/moxa,moxart-core-clock.txt b/Documentation/devicetree/bindings/clock/moxa,moxart-core-clock.txt
> new file mode 100644
> index 0000000..cf69361
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/moxa,moxart-core-clock.txt
> @@ -0,0 +1,19 @@
> +Device Tree Clock bindings for arch-moxart
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +MOXA ART SoCs allow to determine core clock frequencies by reading
> +a register.
> +
> +Required properties:
> +- compatible : Should be "moxa,moxart-core-clock"
> +- reg : Should contain registers location and length
> +
> +For example:
> +
> + clk: core-clock@...00000 {
> + compatible = "moxa,moxart-core-clock";
> + reg = <0x98100000 0x34>;
> + };
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 4038c2b..933622f 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_COMMON_CLK) += clk-composite.o
>
> # SoCs specific
> obj-$(CONFIG_ARCH_BCM2835) += clk-bcm2835.o
> +obj-$(CONFIG_ARCH_MOXART) += clk-moxart.o
> obj-$(CONFIG_ARCH_NOMADIK) += clk-nomadik.o
> obj-$(CONFIG_ARCH_HIGHBANK) += clk-highbank.o
> obj-$(CONFIG_ARCH_NSPIRE) += clk-nspire.o
> diff --git a/drivers/clk/clk-moxart.c b/drivers/clk/clk-moxart.c
> new file mode 100644
> index 0000000..79c27f4
> --- /dev/null
> +++ b/drivers/clk/clk-moxart.c
> @@ -0,0 +1,82 @@
> +/*
> + * MOXA ART SoCs clock driver.
> + *
> + * Copyright (C) 2013 Jonas Jensen
> + *
> + * Jonas Jensen <jonas.jensen@...il.com>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/clkdev.h>
> +
> +static const struct of_device_id moxart_apb_clock_match[] = {
> + { .compatible = "moxa,moxart-apb-clock" },
> + { }
> +};
> +
> +void __init moxart_of_clk_init(struct device_node *node)
> +{
> + static void __iomem *base;
> + struct device_node *clk_node;
> + struct clk *clk;
> + unsigned long rate;
> + unsigned int mul, val, div;
> +
> + base = of_iomap(node, 0);
> + if (IS_ERR(base))
> + panic("%s: of_iomap failed\n", node->full_name);
> +
> + clk_node = of_find_matching_node(NULL, moxart_apb_clock_match);
> + if (!clk_node)
> + panic("%s: can't find clock DT node\n", node->full_name);
> +
> + mul = (readl(base + 0x30) >> 3) & 0x1ff;
> + val = (readl(base + 0x0c) >> 4) & 0x7;
> +
> + switch (val) {
> + case 1:
> + div = 3;
> + break;
> + case 2:
> + div = 4;
> + break;
> + case 3:
> + div = 6;
> + break;
> + case 4:
> + div = 8;
> + break;
> + default:
> + div = 2;
> + break;
> + }
> +
> + /*
> + * the rate calculation below is only tested and proven
> + * to be true for UC-7112-LX
> + *
> + * UC-7112-LX: mul=80 val=0
> + *
> + * to support other moxart SoC hardware, this may need
> + * a change, though it's possible it works there too
> + */
> + rate = (mul * 1200000 / div);
> +
> + clk = clk_register_fixed_rate(NULL, "clkapb", NULL, CLK_IS_ROOT, rate);
> + clk_register_clkdev(clk, NULL, "clkapb");
> + of_clk_add_provider(clk_node, of_clk_src_simple_get, clk);
This confuses me. moxart_of_clk_init gets called because there was a
"moxa,moxart-core-clock", node in the dt, but the driver only seems to
use the information to figure out the configuration of another clock
("moxa,moxart-apb-clock"), and never registers a clock specifically for
the core-clock.
I couldn't find "moxa,moxart-apb-clock" described in mainline. COuld you
describe the relationship between core-clock and apb-clock?
Thanks,
Mark.
> +
> + iounmap(base);
> +}
> +CLK_OF_DECLARE(moxart_core_clock, "moxa,moxart-core-clock", moxart_of_clk_init);
> --
> 1.8.2.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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