Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965037Ab3DJQ2N (ORCPT ); Wed, 10 Apr 2013 12:28:13 -0400 Received: from mail.abilis.ch ([195.70.19.74]:27346 "EHLO mail.abilis.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936994Ab3DJQ2L convert rfc822-to-8bit (ORCPT ); Wed, 10 Apr 2013 12:28:11 -0400 Date: Wed, 10 Apr 2013 18:27:47 +0200 From: Christian Ruppert To: Gregory CLEMENT Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Mike Turquette , linux-doc@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Rob Herring , Grant Likely , Rob Landley Subject: Re: [PATCH] clk: Add device tree binding to clk-fixed-factor Message-ID: <20130410162747.GG32603@ab42.lan> References: <1365608443-30350-1-git-send-email-christian.ruppert@abilis.com> <51658BA9.7030508@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <51658BA9.7030508@free-electrons.com> User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5433 Lines: 148 Hi Gregory, We use derived clocks with fixed ratios for our TB10x platform. I originally had this in the platform code but Vineet (the platform maintainer) rightly pointed out that the common clock framework would be the correct place for it. Is there any reason not to support this functionality? After all, the generic fixed rate clock also has a device tree binding and I'd guess we're not the only ones statically deriving one clock from another in our SOCs. Greetings, Christian On Wed, Apr 10, 2013 at 05:56:25PM +0200, Gregory CLEMENT wrote: > Hi Christian, > > On 04/10/2013 05:40 PM, Christian Ruppert wrote: > > This patch adds a device tree binding for the simple fixed factor clock > > divider/multiplier of the common clock tree binding. > > This patch remind me of something : > http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/116405.html > > Do you have a use case for it, this time? > > My version have been hold off waiting for an user for it. > Will you need it for a driver? > > Regards, > > > > > Signed-off-by: Christian Ruppert > > --- > > .../bindings/clock/fixed-factor-clkdiv.txt | 24 +++++++++++++++ > > drivers/clk/clk-fixed-factor.c | 32 ++++++++++++++++++++ > > include/linux/clk-provider.h | 1 + > > 3 files changed, 57 insertions(+), 0 deletions(-) > > create mode 100644 Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt > > > > diff --git a/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt b/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt > > new file mode 100644 > > index 0000000..352bac4 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt > > @@ -0,0 +1,24 @@ > > +Device Tree Clock bindings for plat-tb10x > > + > > +This binding uses the common clock binding[1]. > > + > > +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt > > + > > +Required properties: > > +- compatible : shall be "fixed-factor-clkdiv" > > +- #clock-cells: from common clock binding; shall be set to 0 > > +- clocks: shall be the input parent clock phandle for the clock. > > +- clock-mult: defines the multiplication factor of the output clock frequency > > + wrt. the input clock frequency. > > +- clock-div: defines the division factor of the output clock frequency wrt. > > + the input clock frequency. > > + > > +Example: > > +cpu_clk: clkdiv_cpu { /* CPU clock derived from pll0. 1/2 of pll frequency */ > > + compatible = "fixed-factor-clkdiv"; > > + #clock-cells = <0>; > > + clocks = <&pll0>; > > + clock-mult = <1>; > > + clock-div = <2>; > > + clock-output-names = "cpu_clk"; > > +}; > > diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c > > index 1ef271e..85e45f1 100644 > > --- a/drivers/clk/clk-fixed-factor.c > > +++ b/drivers/clk/clk-fixed-factor.c > > @@ -11,6 +11,7 @@ > > #include > > #include > > #include > > +#include > > > > /* > > * DOC: basic fixed multiplier and divider clock that cannot gate > > @@ -96,3 +97,34 @@ struct clk *clk_register_fixed_factor(struct device *dev, const char *name, > > > > return clk; > > } > > + > > +#ifdef CONFIG_OF > > +/** > > + * of_fixed_factor_clkdiv_setup() - Set up simple fixed factor clock divider > > + */ > > +void of_fixed_factor_clkdiv_setup(struct device_node *node) > > +{ > > + struct clk *clk; > > + const char *clk_name = node->name; > > + const char *parent_name; > > + u32 mult, div; > > + > > + if (of_property_read_u32(node, "clock-mult", &mult)) > > + return; > > + > > + if (of_property_read_u32(node, "clock-div", &div)) > > + return; > > + > > + parent_name = of_clk_get_parent_name(node, 0); > > + > > + of_property_read_string(node, "clock-output-names", &clk_name); > > + > > + clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0, > > + mult, div); > > + if (!IS_ERR(clk)) > > + of_clk_add_provider(node, of_clk_src_simple_get, clk); > > +} > > +EXPORT_SYMBOL_GPL(of_fixed_factor_clkdiv_setup); > > +CLK_OF_DECLARE(fixed_clkdiv, "fixed-factor-clkdiv", > > + of_fixed_factor_clkdiv_setup); > > +#endif > > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > > index 7f197d7..d4937cf 100644 > > --- a/include/linux/clk-provider.h > > +++ b/include/linux/clk-provider.h > > @@ -184,6 +184,7 @@ struct clk *clk_register_fixed_rate(struct device *dev, const char *name, > > unsigned long fixed_rate); > > > > void of_fixed_clk_setup(struct device_node *np); > > +void of_fixed_factor_clkdiv_setup(struct device_node *node); > > > > /** > > * struct clk_gate - gating clock > > > > > -- > Gregory Clement, Free Electrons > Kernel, drivers, real-time and embedded Linux > development, consulting, training and support. > http://free-electrons.com -- Christian Ruppert , /| Tel: +41/(0)22 816 19-42 //| 3, Chemin du Pr?-Fleuri _// | bilis Systems CH-1228 Plan-les-Ouates -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/