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Commit caa279dd authored by James Hogan's avatar James Hogan
Browse files

metag: init common clk and use "core" clk 



If the common clock framework is enabled, call of_clk_init(NULL) in
time_init() to register device tree clocks with the clock framework.

After this time_init() calls a new function init_metag_clocks(), which
looks for a clock named "core" in the node compatible with "img,meta"
(usually the root node). If found the get_core_freq machine callback is
overridden to obtain the core clock frequency using that clock.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: devicetree-discuss@lists.ozlabs.org
parent c24d2976

Documentation/devicetree/bindings/metag/meta.txt

0 → 100644
+30 −0
Original line number Diff line number Diff line 
* Meta Processor Binding



This binding specifies what properties must be available in the device tree

representation of a Meta Processor Core, which is the root node in the tree.



Required properties:



    - compatible: Specifies the compatibility list for the Meta processor.

      The type shall be <string> and the value shall include "img,meta".



Optional properties:



    - clocks: Clock consumer specifiers as described in

      Documentation/devicetree/bindings/clock/clock-bindings.txt



    - clock-names: Clock consumer names as described in

      Documentation/devicetree/bindings/clock/clock-bindings.txt.



Clocks are identified by name. Valid clocks are:



    - "core": The Meta core clock from which the Meta timers are derived.



* Examples



/ {

	compatible = "toumaz,tz1090", "img,meta";



	clocks = <&meta_core_clk>;

	clock-names = "core";

};

arch/metag/include/asm/clock.h

+8 −0
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
 *			core frequency will be determined like this:

 *			Meta 1: based on loops_per_jiffy.

 *			Meta 2: (EXPAND_TIMER_DIV + 1) MHz.

 *			If a "core" clock is provided by the device tree, it

 *			will override this function.

 */

struct meta_clock_desc {

	unsigned long		(*get_core_freq)(void);
@@ -26,6 +28,12 @@ struct meta_clock_desc { 


extern struct meta_clock_desc _meta_clock;



/*

 * Perform platform clock initialisation, reading clocks from device tree etc.

 * Only accessible during boot.

 */

void init_metag_clocks(void);



/*

 * Set up the default clock, ensuring all callbacks are valid - only accessible

 * during boot.

arch/metag/kernel/clock.c

+56 −1
Original line number Diff line number Diff line
@@ -8,8 +8,10 @@ 
 * published by the Free Software Foundation.

 */



#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/io.h>

#include <linux/of.h>



#include <asm/param.h>

#include <asm/clock.h>
@@ -34,8 +36,61 @@ static unsigned long get_core_freq_default(void) 
#endif

}



static struct clk *clk_core;



/* Clk based get_core_freq callback. */

static unsigned long get_core_freq_clk(void)

{

	return clk_get_rate(clk_core);

}



/**

 * init_metag_core_clock() - Set up core clock from devicetree.

 *

 * Checks to see if a "core" clock is provided in the device tree, and overrides

 * the get_core_freq callback to use it.

 */

static void __init init_metag_core_clock(void)

{

	/*

	 * See if a core clock is provided by the devicetree (and

	 * registered by the init callback above).

	 */

	struct device_node *node;

	node = of_find_compatible_node(NULL, NULL, "img,meta");

	if (!node) {

		pr_warn("%s: no compatible img,meta DT node found\n",

			__func__);

		return;

	}



	clk_core = of_clk_get_by_name(node, "core");

	if (IS_ERR(clk_core)) {

		pr_warn("%s: no core clock found in DT\n",

			__func__);

		return;

	}



	/*

	 * Override the core frequency callback to use

	 * this clk.

	 */

	_meta_clock.get_core_freq = get_core_freq_clk;

}



/**

 * init_metag_clocks() - Set up clocks from devicetree.

 *

 * Set up important clocks from device tree. In particular any needed for clock

 * sources.

 */

void __init init_metag_clocks(void)

{

	init_metag_core_clock();

}



/**

 * setup_meta_clocks() - Set up the Meta clock.

 * setup_meta_clocks() - Early set up of the Meta clock.

 * @desc:	Clock descriptor usually provided by machine description

 *

 * Ensures all callbacks are valid.

arch/metag/kernel/time.c

+12 −2
Original line number Diff line number Diff line
@@ -5,11 +5,21 @@ 
 *

 */



#include <linux/init.h>



#include <clocksource/metag_generic.h>

#include <linux/clk-provider.h>

#include <linux/init.h>

#include <asm/clock.h>



void __init time_init(void)

{

#ifdef CONFIG_COMMON_CLK

	/* Init clocks from device tree */

	of_clk_init(NULL);

#endif



	/* Init meta clocks, particularly the core clock */

	init_metag_clocks();



	/* Set up the timer clock sources */

	metag_generic_timer_init();

}