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Message-ID: <20140331200620.GA13881@kroah.com>
Date: Mon, 31 Mar 2014 13:06:20 -0700
From: Greg KH <gregkh@...uxfoundation.org>
To: Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, mturquette@...aro.org,
linux@....linux.org.uk, robh+dt@...nel.org,
grant.likely@...aro.org, mark.rutland@....com,
galak@...eaurora.org, kyungmin.park@...sung.com,
sw0312.kim@...sung.com, m.szyprowski@...sung.com,
t.figa@...sung.com, laurent.pinchart@...asonboard.com,
s.hauer@...gutronix.de
Subject: Re: [PATCH RFC v4 2/2] clk: Add handling of clk parent and rate
assigned from DT
On Mon, Mar 31, 2014 at 06:41:56PM +0200, Sylwester Nawrocki wrote:
> This function adds a helper function to configure clock parents and rates
> as specified in clock-parents, clock-rates DT properties for a consumer
> device and a call to it before driver is bound to a device.
>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
> ---
> Changes since v3:
> - added detailed description of the assigned-clocks subnode,
> - clk-conf.c is now excluded when CONFIG_OF is not set,
> - s/of_clk_device_setup/of_clk_device_init,
> - added missing 'static inline' to the function stub definition.
>
> Changes since v2:
> - edited in clock-bindings.txt, added note about 'assigned-clocks'
> subnode which may be used to specify "global" clocks configuration
> at a clock provider node,
> - moved of_clk_device_setup() function declaration from clk-provider.h
> to clk-conf.h so required function stubs are available when
> CONFIG_COMMON_CLK is not enabled,
>
> Changes since v1:
> - the helper function to parse and set assigned clock parents and
> rates made public so it is available to clock providers to call
> directly;
> - dropped the platform bus notification and call of_clk_device_setup()
> is is now called from the driver core, rather than from the
> notification callback;
> - s/of_clk_get_list_entry/of_clk_get_by_property.
> ---
> .../devicetree/bindings/clock/clock-bindings.txt | 42 ++++++++++
> drivers/base/dd.c | 7 ++
> drivers/clk/Makefile | 3 +
> drivers/clk/clk-conf.c | 87 ++++++++++++++++++++
> drivers/clk/clk.c | 10 ++-
> include/linux/clk/clk-conf.h | 19 +++++
> 6 files changed, 167 insertions(+), 1 deletion(-)
> create mode 100644 drivers/clk/clk-conf.c
> create mode 100644 include/linux/clk/clk-conf.h
>
> diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> index 700e7aa..59fbb4e 100644
> --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
> +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> @@ -132,3 +132,45 @@ clock signal, and a UART.
> ("pll" and "pll-switched").
> * The UART has its baud clock connected the external oscillator and its
> register clock connected to the PLL clock (the "pll-switched" signal)
> +
> +==Assigned clock parents and rates==
> +
> +Some platforms require static initial configuration of parts of the clocks
> +controller. Such a configuration can be specified in a clock consumer node
> +through clock-parents and clock-rates DT properties. The former should
> +contain a list of parent clocks in form of phandle and clock specifier pairs,
> +the latter the list of assigned clock frequency values (one cell each).
> +
> + uart@...0 {
> + compatible = "fsl,imx-uart";
> + reg = <0xa000 0x1000>;
> + ...
> + clocks = <&clkcon 0>, <&clkcon 3>;
> + clock-names = "baud", "mux";
> +
> + clock-parents = <0>, <&pll 1>;
> + clock-rates = <460800>;
> + };
> +
> +In this example the pll is set as parent of "mux" clock and frequency of "baud"
> +clock is specified as 460800 Hz.
> +
> +Configuring a clock parent and rate through the device node that uses
> +the clock can be done only for clocks that have a single user. Specifying
> +conflicting parent or rate configuration in multiple consumer nodes for
> +a shared clock is forbidden.
> +
> +Configuration of common clocks, which affect multiple consumer devices
> +can be specified in a dedicated 'assigned-clocks' subnode of a clock
> +provider node, e.g.:
> +
> + clkcon {
> + ...
> + #clock-cells = <1>;
> +
> + assigned-clocks {
> + clocks = <&clkcon 16>, <&clkcon 17>;
> + clock-parents = <0>, <&clkcon 1>;
> + clock-rates = <200000>;
> + };
> + };
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 0605176..4c633e7 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -25,6 +25,7 @@
> #include <linux/async.h>
> #include <linux/pm_runtime.h>
> #include <linux/pinctrl/devinfo.h>
> +#include <linux/clk/clk-conf.h>
>
> #include "base.h"
> #include "power/power.h"
> @@ -278,6 +279,12 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> if (ret)
> goto probe_failed;
>
> + if (dev->of_node) {
> + ret = of_clk_device_init(dev->of_node);
> + if (ret)
> + goto probe_failed;
> + }
> +
> if (driver_sysfs_add(dev)) {
> printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
> __func__, dev_name(dev));
I don't understand why you need the driver core to initialize this one
type of thing? That should be in a driver, or in a class, or at worse
case, the platform code.
What makes clocks so "unique" here?
greg k-h
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