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Commit df70aeef authored by Nicolas Ferre's avatar Nicolas Ferre Committed by Stephen Boyd
Browse files

clk: at91: add generated clock driver 



Add a new type of clocks that can be provided to a peripheral.
In addition to the peripheral clock, this new clock that can use several
input clocks as parents can generate divided rates.
This would allow a peripheral to have finer grained clocks for generating
a baud rate, clocking an asynchronous part or having more
options in frequency.

Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
[sboyd@codeaurora.org: Transition to new clk_hw provider APIs]
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent a5752e57

Documentation/devicetree/bindings/clock/at91-clock.txt

+35 −0
Original line number Diff line number Diff line
@@ -77,6 +77,9 @@ Required properties: 
	"atmel,sama5d4-clk-h32mx":

		at91 h32mx clock



	"atmel,sama5d2-clk-generated":

		at91 generated clock



Required properties for SCKC node:

- reg : defines the IO memory reserved for the SCKC.

- #size-cells : shall be 0 (reg is used to encode clk id).
@@ -461,3 +464,35 @@ For example: 
		compatible = "atmel,sama5d4-clk-h32mx";

		clocks = <&mck>;

	};



Required properties for generated clocks:

- #size-cells : shall be 0 (reg is used to encode clk id).

- #address-cells : shall be 1 (reg is used to encode clk id).

- clocks : shall be the generated clock source phandles.

	e.g. clocks = <&clk32k>, <&main>, <&plladiv>, <&utmi>, <&mck>, <&audio_pll_pmc>;

- name: device tree node describing a specific generated clock.

	* #clock-cells : from common clock binding; shall be set to 0.

	* reg: peripheral id. See Atmel's datasheets to get a full

	  list of peripheral ids.

	* atmel,clk-output-range : minimum and maximum clock frequency

	  (two u32 fields).



For example:

	gck {

		compatible = "atmel,sama5d2-clk-generated";

		#address-cells = <1>;

		#size-cells = <0>;

		clocks = <&clk32k>, <&main>, <&plladiv>, <&utmi>, <&mck>, <&audio_pll_pmc>;



		tcb0_gclk: tcb0_gclk {

			#clock-cells = <0>;

			reg = <35>;

			atmel,clk-output-range = <0 83000000>;

		};



		pwm_gclk: pwm_gclk {

			#clock-cells = <0>;

			reg = <38>;

			atmel,clk-output-range = <0 83000000>;

		};

	};

arch/arm/mach-at91/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -102,6 +102,9 @@ config HAVE_AT91_SMD 
config HAVE_AT91_H32MX

	bool



config HAVE_AT91_GENERATED_CLK

	bool



config SOC_SAM_V4_V5

	bool

drivers/clk/at91/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -10,3 +10,4 @@ obj-$(CONFIG_HAVE_AT91_UTMI) += clk-utmi.o 
obj-$(CONFIG_HAVE_AT91_USB_CLK)		+= clk-usb.o

obj-$(CONFIG_HAVE_AT91_SMD)		+= clk-smd.o

obj-$(CONFIG_HAVE_AT91_H32MX)		+= clk-h32mx.o

obj-$(CONFIG_HAVE_AT91_GENERATED_CLK)	+= clk-generated.o

drivers/clk/at91/clk-generated.c

0 → 100644
+306 −0
Original line number Diff line number Diff line 
/*

 *  Copyright (C) 2015 Atmel Corporation,

 *                     Nicolas Ferre <nicolas.ferre@atmel.com>

 *

 * Based on clk-programmable & clk-peripheral drivers by Boris BREZILLON.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 */



#include <linux/clk-provider.h>

#include <linux/clkdev.h>

#include <linux/clk/at91_pmc.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/io.h>



#include "pmc.h"



#define PERIPHERAL_MAX		64

#define PERIPHERAL_ID_MIN	2



#define GENERATED_SOURCE_MAX	6

#define GENERATED_MAX_DIV	255



struct clk_generated {

	struct clk_hw hw;

	struct at91_pmc *pmc;

	struct clk_range range;

	u32 id;

	u32 gckdiv;

	u8 parent_id;

};



#define to_clk_generated(hw) \

	container_of(hw, struct clk_generated, hw)



static int clk_generated_enable(struct clk_hw *hw)

{

	struct clk_generated *gck = to_clk_generated(hw);

	struct at91_pmc *pmc = gck->pmc;

	u32 tmp;



	pr_debug("GCLK: %s, gckdiv = %d, parent id = %d\n",

		 __func__, gck->gckdiv, gck->parent_id);



	pmc_lock(pmc);

	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));

	tmp = pmc_read(pmc, AT91_PMC_PCR) &

			~(AT91_PMC_PCR_GCKDIV_MASK | AT91_PMC_PCR_GCKCSS_MASK);

	pmc_write(pmc, AT91_PMC_PCR, tmp | AT91_PMC_PCR_GCKCSS(gck->parent_id)

					 | AT91_PMC_PCR_CMD

					 | AT91_PMC_PCR_GCKDIV(gck->gckdiv)

					 | AT91_PMC_PCR_GCKEN);

	pmc_unlock(pmc);

	return 0;

}



static void clk_generated_disable(struct clk_hw *hw)

{

	struct clk_generated *gck = to_clk_generated(hw);

	struct at91_pmc *pmc = gck->pmc;

	u32 tmp;



	pmc_lock(pmc);

	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));

	tmp = pmc_read(pmc, AT91_PMC_PCR) & ~AT91_PMC_PCR_GCKEN;

	pmc_write(pmc, AT91_PMC_PCR, tmp | AT91_PMC_PCR_CMD);

	pmc_unlock(pmc);

}



static int clk_generated_is_enabled(struct clk_hw *hw)

{

	struct clk_generated *gck = to_clk_generated(hw);

	struct at91_pmc *pmc = gck->pmc;

	int ret;



	pmc_lock(pmc);

	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));

	ret = !!(pmc_read(pmc, AT91_PMC_PCR) & AT91_PMC_PCR_GCKEN);

	pmc_unlock(pmc);



	return ret;

}



static unsigned long

clk_generated_recalc_rate(struct clk_hw *hw,

			  unsigned long parent_rate)

{

	struct clk_generated *gck = to_clk_generated(hw);



	return DIV_ROUND_CLOSEST(parent_rate, gck->gckdiv + 1);

}



static int clk_generated_determine_rate(struct clk_hw *hw,

					struct clk_rate_request *req)

{

	struct clk_generated *gck = to_clk_generated(hw);

	struct clk_hw *parent = NULL;

	long best_rate = -EINVAL;

	unsigned long tmp_rate, min_rate;

	int best_diff = -1;

	int tmp_diff;

	int i;



	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {

		u32 div;

		unsigned long parent_rate;



		parent = clk_hw_get_parent_by_index(hw, i);

		if (!parent)

			continue;



		parent_rate = clk_hw_get_rate(parent);

		min_rate = DIV_ROUND_CLOSEST(parent_rate, GENERATED_MAX_DIV + 1);

		if (!parent_rate ||

		    (gck->range.max && min_rate > gck->range.max))

			continue;



		for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {

			tmp_rate = DIV_ROUND_CLOSEST(parent_rate, div);

			tmp_diff = abs(req->rate - tmp_rate);



			if (best_diff < 0 || best_diff > tmp_diff) {

				best_rate = tmp_rate;

				best_diff = tmp_diff;

				req->best_parent_rate = parent_rate;

				req->best_parent_hw = parent;

			}



			if (!best_diff || tmp_rate < req->rate)

				break;

		}



		if (!best_diff)

			break;

	}



	pr_debug("GCLK: %s, best_rate = %ld, parent clk: %s @ %ld\n",

		 __func__, best_rate,

		 __clk_get_name((req->best_parent_hw)->clk),

		 req->best_parent_rate);



	if (best_rate < 0)

		return best_rate;



	req->rate = best_rate;

	return 0;

}



/* No modification of hardware as we have the flag CLK_SET_PARENT_GATE set */

static int clk_generated_set_parent(struct clk_hw *hw, u8 index)

{

	struct clk_generated *gck = to_clk_generated(hw);



	if (index >= clk_hw_get_num_parents(hw))

		return -EINVAL;



	gck->parent_id = index;

	return 0;

}



static u8 clk_generated_get_parent(struct clk_hw *hw)

{

	struct clk_generated *gck = to_clk_generated(hw);



	return gck->parent_id;

}



/* No modification of hardware as we have the flag CLK_SET_RATE_GATE set */

static int clk_generated_set_rate(struct clk_hw *hw,

				  unsigned long rate,

				  unsigned long parent_rate)

{

	struct clk_generated *gck = to_clk_generated(hw);

	u32 div;



	if (!rate)

		return -EINVAL;



	if (gck->range.max && rate > gck->range.max)

		return -EINVAL;



	div = DIV_ROUND_CLOSEST(parent_rate, rate);

	if (div > GENERATED_MAX_DIV + 1 || !div)

		return -EINVAL;



	gck->gckdiv = div - 1;

	return 0;

}



static const struct clk_ops generated_ops = {

	.enable = clk_generated_enable,

	.disable = clk_generated_disable,

	.is_enabled = clk_generated_is_enabled,

	.recalc_rate = clk_generated_recalc_rate,

	.determine_rate = clk_generated_determine_rate,

	.get_parent = clk_generated_get_parent,

	.set_parent = clk_generated_set_parent,

	.set_rate = clk_generated_set_rate,

};



/**

 * clk_generated_startup - Initialize a given clock to its default parent and

 * divisor parameter.

 *

 * @gck:	Generated clock to set the startup parameters for.

 *

 * Take parameters from the hardware and update local clock configuration

 * accordingly.

 */

static void clk_generated_startup(struct clk_generated *gck)

{

	struct at91_pmc *pmc = gck->pmc;

	u32 tmp;



	pmc_lock(pmc);

	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));

	tmp = pmc_read(pmc, AT91_PMC_PCR);

	pmc_unlock(pmc);



	gck->parent_id = (tmp & AT91_PMC_PCR_GCKCSS_MASK)

					>> AT91_PMC_PCR_GCKCSS_OFFSET;

	gck->gckdiv = (tmp & AT91_PMC_PCR_GCKDIV_MASK)

					>> AT91_PMC_PCR_GCKDIV_OFFSET;

}



static struct clk * __init

at91_clk_register_generated(struct at91_pmc *pmc, const char *name,

			    const char **parent_names, u8 num_parents,

			    u8 id, const struct clk_range *range)

{

	struct clk_generated *gck;

	struct clk *clk = NULL;

	struct clk_init_data init;



	gck = kzalloc(sizeof(*gck), GFP_KERNEL);

	if (!gck)

		return ERR_PTR(-ENOMEM);



	init.name = name;

	init.ops = &generated_ops;

	init.parent_names = parent_names;

	init.num_parents = num_parents;

	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;



	gck->id = id;

	gck->hw.init = &init;

	gck->pmc = pmc;

	gck->range = *range;



	clk = clk_register(NULL, &gck->hw);

	if (IS_ERR(clk))

		kfree(gck);

	else

		clk_generated_startup(gck);



	return clk;

}



void __init of_sama5d2_clk_generated_setup(struct device_node *np,

					   struct at91_pmc *pmc)

{

	int num;

	u32 id;

	const char *name;

	struct clk *clk;

	int num_parents;

	const char *parent_names[GENERATED_SOURCE_MAX];

	struct device_node *gcknp;

	struct clk_range range = CLK_RANGE(0, 0);



	num_parents = of_clk_get_parent_count(np);

	if (num_parents <= 0 || num_parents > GENERATED_SOURCE_MAX)

		return;



	of_clk_parent_fill(np, parent_names, num_parents);



	num = of_get_child_count(np);

	if (!num || num > PERIPHERAL_MAX)

		return;



	for_each_child_of_node(np, gcknp) {

		if (of_property_read_u32(gcknp, "reg", &id))

			continue;



		if (id < PERIPHERAL_ID_MIN || id >= PERIPHERAL_MAX)

			continue;



		if (of_property_read_string(np, "clock-output-names", &name))

			name = gcknp->name;



		of_at91_get_clk_range(gcknp, "atmel,clk-output-range",

				      &range);



		clk = at91_clk_register_generated(pmc, name, parent_names,

						  num_parents, id, &range);

		if (IS_ERR(clk))

			continue;



		of_clk_add_provider(gcknp, of_clk_src_simple_get, clk);

	}

}

drivers/clk/at91/pmc.c

+6 −0
Original line number Diff line number Diff line
@@ -376,6 +376,12 @@ static const struct of_device_id pmc_clk_ids[] __initconst = { 
		.compatible = "atmel,sama5d4-clk-h32mx",

		.data = of_sama5d4_clk_h32mx_setup,

	},

#endif

#if defined(CONFIG_HAVE_AT91_GENERATED_CLK)

	{

		.compatible = "atmel,sama5d2-clk-generated",

		.data = of_sama5d2_clk_generated_setup,

	},

#endif

	{ /*sentinel*/ }

};