drivers/clk/at91/clk-slow.c - third_party/linux - Git at Google

 /*
  * drivers/clk/at91/clk-slow.c
  *
  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
  *
  * 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/delay.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/sched.h>
 #include <linux/wait.h>

 #include "pmc.h"
 #include "sckc.h"

 #define SLOW_CLOCK_FREQ		32768
 #define SLOWCK_SW_CYCLES	5
 #define SLOWCK_SW_TIME_USEC	((SLOWCK_SW_CYCLES * USEC_PER_SEC) / \
 				 SLOW_CLOCK_FREQ)

 #define	AT91_SCKC_CR			0x00
 #define		AT91_SCKC_RCEN		(1 << 0)
 #define		AT91_SCKC_OSC32EN	(1 << 1)
 #define		AT91_SCKC_OSC32BYP	(1 << 2)
 #define		AT91_SCKC_OSCSEL	(1 << 3)

 struct clk_slow_osc {
 	struct clk_hw hw;
 	void __iomem *sckcr;
 	unsigned long startup_usec;
 };

 #define to_clk_slow_osc(hw) container_of(hw, struct clk_slow_osc, hw)

 struct clk_slow_rc_osc {
 	struct clk_hw hw;
 	void __iomem *sckcr;
 	unsigned long frequency;
 	unsigned long accuracy;
 	unsigned long startup_usec;
 };

 #define to_clk_slow_rc_osc(hw) container_of(hw, struct clk_slow_rc_osc, hw)

 struct clk_sam9260_slow {
 	struct clk_hw hw;
 	struct at91_pmc *pmc;
 };

 #define to_clk_sam9260_slow(hw) container_of(hw, struct clk_sam9260_slow, hw)

 struct clk_sam9x5_slow {
 	struct clk_hw hw;
 	void __iomem *sckcr;
 	u8 parent;
 };

 #define to_clk_sam9x5_slow(hw) container_of(hw, struct clk_sam9x5_slow, hw)

 static struct clk *slow_clk;

 static int clk_slow_osc_prepare(struct clk_hw *hw)
 {
 	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
 	void __iomem *sckcr = osc->sckcr;
 	u32 tmp = readl(sckcr);

 	if (tmp & AT91_SCKC_OSC32BYP)
 		return 0;

 	writel(tmp | AT91_SCKC_OSC32EN, sckcr);

 	usleep_range(osc->startup_usec, osc->startup_usec + 1);

 	return 0;
 }

 static void clk_slow_osc_unprepare(struct clk_hw *hw)
 {
 	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
 	void __iomem *sckcr = osc->sckcr;
 	u32 tmp = readl(sckcr);

 	if (tmp & AT91_SCKC_OSC32BYP)
 		return;

 	writel(tmp & ~AT91_SCKC_OSC32EN, sckcr);
 }

 static int clk_slow_osc_is_prepared(struct clk_hw *hw)
 {
 	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
 	void __iomem *sckcr = osc->sckcr;
 	u32 tmp = readl(sckcr);

 	if (tmp & AT91_SCKC_OSC32BYP)
 		return 1;

 	return !!(tmp & AT91_SCKC_OSC32EN);
 }

 static const struct clk_ops slow_osc_ops = {
 	.prepare = clk_slow_osc_prepare,
 	.unprepare = clk_slow_osc_unprepare,
 	.is_prepared = clk_slow_osc_is_prepared,
 };

 static struct clk * __init
 at91_clk_register_slow_osc(void __iomem *sckcr,
 			   const char *name,
 			   const char *parent_name,
 			   unsigned long startup,
 			   bool bypass)
 {
 	struct clk_slow_osc *osc;
 	struct clk *clk = NULL;
 	struct clk_init_data init;

 	if (!sckcr || !name || !parent_name)
 		return ERR_PTR(-EINVAL);

 	osc = kzalloc(sizeof(*osc), GFP_KERNEL);
 	if (!osc)
 		return ERR_PTR(-ENOMEM);

 	init.name = name;
 	init.ops = &slow_osc_ops;
 	init.parent_names = &parent_name;
 	init.num_parents = 1;
 	init.flags = CLK_IGNORE_UNUSED;

 	osc->hw.init = &init;
 	osc->sckcr = sckcr;
 	osc->startup_usec = startup;

 	if (bypass)
 		writel((readl(sckcr) & ~AT91_SCKC_OSC32EN) | AT91_SCKC_OSC32BYP,
 		       sckcr);

 	clk = clk_register(NULL, &osc->hw);
 	if (IS_ERR(clk))
 		kfree(osc);

 	return clk;
 }

 void __init of_at91sam9x5_clk_slow_osc_setup(struct device_node *np,
 					     void __iomem *sckcr)
 {
 	struct clk *clk;
 	const char *parent_name;
 	const char *name = np->name;
 	u32 startup;
 	bool bypass;

 	parent_name = of_clk_get_parent_name(np, 0);
 	of_property_read_string(np, "clock-output-names", &name);
 	of_property_read_u32(np, "atmel,startup-time-usec", &startup);
 	bypass = of_property_read_bool(np, "atmel,osc-bypass");

 	clk = at91_clk_register_slow_osc(sckcr, name, parent_name, startup,
 					 bypass);
 	if (IS_ERR(clk))
 		return;

 	of_clk_add_provider(np, of_clk_src_simple_get, clk);
 }

 static unsigned long clk_slow_rc_osc_recalc_rate(struct clk_hw *hw,
 						 unsigned long parent_rate)
 {
 	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

 	return osc->frequency;
 }

 static unsigned long clk_slow_rc_osc_recalc_accuracy(struct clk_hw *hw,
 						     unsigned long parent_acc)
 {
 	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

 	return osc->accuracy;
 }

 static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
 {
 	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);
 	void __iomem *sckcr = osc->sckcr;

 	writel(readl(sckcr) | AT91_SCKC_RCEN, sckcr);

 	usleep_range(osc->startup_usec, osc->startup_usec + 1);

 	return 0;
 }

 static void clk_slow_rc_osc_unprepare(struct clk_hw *hw)
 {
 	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);
 	void __iomem *sckcr = osc->sckcr;

 	writel(readl(sckcr) & ~AT91_SCKC_RCEN, sckcr);
 }

 static int clk_slow_rc_osc_is_prepared(struct clk_hw *hw)
 {
 	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

 	return !!(readl(osc->sckcr) & AT91_SCKC_RCEN);
 }

 static const struct clk_ops slow_rc_osc_ops = {
 	.prepare = clk_slow_rc_osc_prepare,
 	.unprepare = clk_slow_rc_osc_unprepare,
 	.is_prepared = clk_slow_rc_osc_is_prepared,
 	.recalc_rate = clk_slow_rc_osc_recalc_rate,
 	.recalc_accuracy = clk_slow_rc_osc_recalc_accuracy,
 };

 static struct clk * __init
 at91_clk_register_slow_rc_osc(void __iomem *sckcr,
 			      const char *name,
 			      unsigned long frequency,
 			      unsigned long accuracy,
 			      unsigned long startup)
 {
 	struct clk_slow_rc_osc *osc;
 	struct clk *clk = NULL;
 	struct clk_init_data init;

 	if (!sckcr || !name)
 		return ERR_PTR(-EINVAL);

 	osc = kzalloc(sizeof(*osc), GFP_KERNEL);
 	if (!osc)
 		return ERR_PTR(-ENOMEM);

 	init.name = name;
 	init.ops = &slow_rc_osc_ops;
 	init.parent_names = NULL;
 	init.num_parents = 0;
 	init.flags = CLK_IS_ROOT | CLK_IGNORE_UNUSED;

 	osc->hw.init = &init;
 	osc->sckcr = sckcr;
 	osc->frequency = frequency;
 	osc->accuracy = accuracy;
 	osc->startup_usec = startup;

 	clk = clk_register(NULL, &osc->hw);
 	if (IS_ERR(clk))
 		kfree(osc);

 	return clk;
 }

 void __init of_at91sam9x5_clk_slow_rc_osc_setup(struct device_node *np,
 						void __iomem *sckcr)
 {
 	struct clk *clk;
 	u32 frequency = 0;
 	u32 accuracy = 0;
 	u32 startup = 0;
 	const char *name = np->name;

 	of_property_read_string(np, "clock-output-names", &name);
 	of_property_read_u32(np, "clock-frequency", &frequency);
 	of_property_read_u32(np, "clock-accuracy", &accuracy);
 	of_property_read_u32(np, "atmel,startup-time-usec", &startup);

 	clk = at91_clk_register_slow_rc_osc(sckcr, name, frequency, accuracy,
 					    startup);
 	if (IS_ERR(clk))
 		return;

 	of_clk_add_provider(np, of_clk_src_simple_get, clk);
 }

 static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index)
 {
 	struct clk_sam9x5_slow *slowck = to_clk_sam9x5_slow(hw);
 	void __iomem *sckcr = slowck->sckcr;
 	u32 tmp;

 	if (index > 1)
 		return -EINVAL;

 	tmp = readl(sckcr);

 	if ((!index && !(tmp & AT91_SCKC_OSCSEL)) ||
 	    (index && (tmp & AT91_SCKC_OSCSEL)))
 		return 0;

 	if (index)
 		tmp |= AT91_SCKC_OSCSEL;
 	else
 		tmp &= ~AT91_SCKC_OSCSEL;

 	writel(tmp, sckcr);

 	usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);

 	return 0;
 }

 static u8 clk_sam9x5_slow_get_parent(struct clk_hw *hw)
 {
 	struct clk_sam9x5_slow *slowck = to_clk_sam9x5_slow(hw);

 	return !!(readl(slowck->sckcr) & AT91_SCKC_OSCSEL);
 }

 static const struct clk_ops sam9x5_slow_ops = {
 	.set_parent = clk_sam9x5_slow_set_parent,
 	.get_parent = clk_sam9x5_slow_get_parent,
 };

 static struct clk * __init
 at91_clk_register_sam9x5_slow(void __iomem *sckcr,
 			      const char *name,
 			      const char **parent_names,
 			      int num_parents)
 {
 	struct clk_sam9x5_slow *slowck;
 	struct clk *clk = NULL;
 	struct clk_init_data init;

 	if (!sckcr || !name || !parent_names || !num_parents)
 		return ERR_PTR(-EINVAL);

 	slowck = kzalloc(sizeof(*slowck), GFP_KERNEL);
 	if (!slowck)
 		return ERR_PTR(-ENOMEM);

 	init.name = name;
 	init.ops = &sam9x5_slow_ops;
 	init.parent_names = parent_names;
 	init.num_parents = num_parents;
 	init.flags = 0;

 	slowck->hw.init = &init;
 	slowck->sckcr = sckcr;
 	slowck->parent = !!(readl(sckcr) & AT91_SCKC_OSCSEL);

 	clk = clk_register(NULL, &slowck->hw);
 	if (IS_ERR(clk))
 		kfree(slowck);
 	else
 		slow_clk = clk;

 	return clk;
 }

 void __init of_at91sam9x5_clk_slow_setup(struct device_node *np,
 					 void __iomem *sckcr)
 {
 	struct clk *clk;
 	const char *parent_names[2];
 	int num_parents;
 	const char *name = np->name;
 	int i;

 	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
 	if (num_parents <= 0 || num_parents > 2)
 		return;

 	for (i = 0; i < num_parents; ++i) {
 		parent_names[i] = of_clk_get_parent_name(np, i);
 		if (!parent_names[i])
 			return;
 	}

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

 	clk = at91_clk_register_sam9x5_slow(sckcr, name, parent_names,
 					    num_parents);
 	if (IS_ERR(clk))
 		return;

 	of_clk_add_provider(np, of_clk_src_simple_get, clk);
 }

 static u8 clk_sam9260_slow_get_parent(struct clk_hw *hw)
 {
 	struct clk_sam9260_slow *slowck = to_clk_sam9260_slow(hw);

 	return !!(pmc_read(slowck->pmc, AT91_PMC_SR) & AT91_PMC_OSCSEL);
 }

 static const struct clk_ops sam9260_slow_ops = {
 	.get_parent = clk_sam9260_slow_get_parent,
 };

 static struct clk * __init
 at91_clk_register_sam9260_slow(struct at91_pmc *pmc,
 			       const char *name,
 			       const char **parent_names,
 			       int num_parents)
 {
 	struct clk_sam9260_slow *slowck;
 	struct clk *clk = NULL;
 	struct clk_init_data init;

 	if (!pmc || !name)
 		return ERR_PTR(-EINVAL);

 	if (!parent_names || !num_parents)
 		return ERR_PTR(-EINVAL);

 	slowck = kzalloc(sizeof(*slowck), GFP_KERNEL);
 	if (!slowck)
 		return ERR_PTR(-ENOMEM);

 	init.name = name;
 	init.ops = &sam9260_slow_ops;
 	init.parent_names = parent_names;
 	init.num_parents = num_parents;
 	init.flags = 0;

 	slowck->hw.init = &init;
 	slowck->pmc = pmc;

 	clk = clk_register(NULL, &slowck->hw);
 	if (IS_ERR(clk))
 		kfree(slowck);
 	else
 		slow_clk = clk;

 	return clk;
 }

 void __init of_at91sam9260_clk_slow_setup(struct device_node *np,
 					  struct at91_pmc *pmc)
 {
 	struct clk *clk;
 	const char *parent_names[2];
 	int num_parents;
 	const char *name = np->name;
 	int i;

 	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
 	if (num_parents != 2)
 		return;

 	for (i = 0; i < num_parents; ++i) {
 		parent_names[i] = of_clk_get_parent_name(np, i);
 		if (!parent_names[i])
 			return;
 	}

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

 	clk = at91_clk_register_sam9260_slow(pmc, name, parent_names,
 					     num_parents);
 	if (IS_ERR(clk))
 		return;

 	of_clk_add_provider(np, of_clk_src_simple_get, clk);
 }

 /*
  * FIXME: All slow clk users are not properly claiming it (get + prepare +
  * enable) before using it.
  * If all users properly claiming this clock decide that they don't need it
  * anymore (or are removed), it is disabled while faulty users are still
  * requiring it, and the system hangs.
  * Prevent this clock from being disabled until all users are properly
  * requesting it.
  * Once this is done we should remove this function and the slow_clk variable.
  */
 static int __init of_at91_clk_slow_retain(void)
 {
 	if (!slow_clk)
 		return 0;

 	__clk_get(slow_clk);
 	clk_prepare_enable(slow_clk);

 	return 0;
 }
 arch_initcall(of_at91_clk_slow_retain);
	/*
	* drivers/clk/at91/clk-slow.c
	*
	* Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
	*
	* 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/delay.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/io.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/sched.h>
	#include <linux/wait.h>

	#include "pmc.h"
	#include "sckc.h"

	#define SLOW_CLOCK_FREQ 32768
	#define SLOWCK_SW_CYCLES 5
	#define SLOWCK_SW_TIME_USEC ((SLOWCK_SW_CYCLES * USEC_PER_SEC) / \
	SLOW_CLOCK_FREQ)

	#define AT91_SCKC_CR 0x00
	#define AT91_SCKC_RCEN (1 << 0)
	#define AT91_SCKC_OSC32EN (1 << 1)
	#define AT91_SCKC_OSC32BYP (1 << 2)
	#define AT91_SCKC_OSCSEL (1 << 3)

	struct clk_slow_osc {
	struct clk_hw hw;
	void __iomem *sckcr;
	unsigned long startup_usec;
	};

	#define to_clk_slow_osc(hw) container_of(hw, struct clk_slow_osc, hw)

	struct clk_slow_rc_osc {
	struct clk_hw hw;
	void __iomem *sckcr;
	unsigned long frequency;
	unsigned long accuracy;
	unsigned long startup_usec;
	};

	#define to_clk_slow_rc_osc(hw) container_of(hw, struct clk_slow_rc_osc, hw)

	struct clk_sam9260_slow {
	struct clk_hw hw;
	struct at91_pmc *pmc;
	};

	#define to_clk_sam9260_slow(hw) container_of(hw, struct clk_sam9260_slow, hw)

	struct clk_sam9x5_slow {
	struct clk_hw hw;
	void __iomem *sckcr;
	u8 parent;
	};

	#define to_clk_sam9x5_slow(hw) container_of(hw, struct clk_sam9x5_slow, hw)

	static struct clk *slow_clk;

	static int clk_slow_osc_prepare(struct clk_hw *hw)
	{
	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
	void __iomem *sckcr = osc->sckcr;
	u32 tmp = readl(sckcr);

	if (tmp & AT91_SCKC_OSC32BYP)
	return 0;

	writel(tmp \| AT91_SCKC_OSC32EN, sckcr);

	usleep_range(osc->startup_usec, osc->startup_usec + 1);

	return 0;
	}

	static void clk_slow_osc_unprepare(struct clk_hw *hw)
	{
	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
	void __iomem *sckcr = osc->sckcr;
	u32 tmp = readl(sckcr);

	if (tmp & AT91_SCKC_OSC32BYP)
	return;

	writel(tmp & ~AT91_SCKC_OSC32EN, sckcr);
	}

	static int clk_slow_osc_is_prepared(struct clk_hw *hw)
	{
	struct clk_slow_osc *osc = to_clk_slow_osc(hw);
	void __iomem *sckcr = osc->sckcr;
	u32 tmp = readl(sckcr);

	if (tmp & AT91_SCKC_OSC32BYP)
	return 1;

	return !!(tmp & AT91_SCKC_OSC32EN);
	}

	static const struct clk_ops slow_osc_ops = {
	.prepare = clk_slow_osc_prepare,
	.unprepare = clk_slow_osc_unprepare,
	.is_prepared = clk_slow_osc_is_prepared,
	};

	static struct clk * __init
	at91_clk_register_slow_osc(void __iomem *sckcr,
	const char *name,
	const char *parent_name,
	unsigned long startup,
	bool bypass)
	{
	struct clk_slow_osc *osc;
	struct clk *clk = NULL;
	struct clk_init_data init;

	if (!sckcr \|\| !name \|\| !parent_name)
	return ERR_PTR(-EINVAL);

	osc = kzalloc(sizeof(*osc), GFP_KERNEL);
	if (!osc)
	return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &slow_osc_ops;
	init.parent_names = &parent_name;
	init.num_parents = 1;
	init.flags = CLK_IGNORE_UNUSED;

	osc->hw.init = &init;
	osc->sckcr = sckcr;
	osc->startup_usec = startup;

	if (bypass)
	writel((readl(sckcr) & ~AT91_SCKC_OSC32EN) \| AT91_SCKC_OSC32BYP,
	sckcr);

	clk = clk_register(NULL, &osc->hw);
	if (IS_ERR(clk))
	kfree(osc);

	return clk;
	}

	void __init of_at91sam9x5_clk_slow_osc_setup(struct device_node *np,
	void __iomem *sckcr)
	{
	struct clk *clk;
	const char *parent_name;
	const char *name = np->name;
	u32 startup;
	bool bypass;

	parent_name = of_clk_get_parent_name(np, 0);
	of_property_read_string(np, "clock-output-names", &name);
	of_property_read_u32(np, "atmel,startup-time-usec", &startup);
	bypass = of_property_read_bool(np, "atmel,osc-bypass");

	clk = at91_clk_register_slow_osc(sckcr, name, parent_name, startup,
	bypass);
	if (IS_ERR(clk))
	return;

	of_clk_add_provider(np, of_clk_src_simple_get, clk);
	}

	static unsigned long clk_slow_rc_osc_recalc_rate(struct clk_hw *hw,
	unsigned long parent_rate)
	{
	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

	return osc->frequency;
	}

	static unsigned long clk_slow_rc_osc_recalc_accuracy(struct clk_hw *hw,
	unsigned long parent_acc)
	{
	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

	return osc->accuracy;
	}

	static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
	{
	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);
	void __iomem *sckcr = osc->sckcr;

	writel(readl(sckcr) \| AT91_SCKC_RCEN, sckcr);

	usleep_range(osc->startup_usec, osc->startup_usec + 1);

	return 0;
	}

	static void clk_slow_rc_osc_unprepare(struct clk_hw *hw)
	{
	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);
	void __iomem *sckcr = osc->sckcr;

	writel(readl(sckcr) & ~AT91_SCKC_RCEN, sckcr);
	}

	static int clk_slow_rc_osc_is_prepared(struct clk_hw *hw)
	{
	struct clk_slow_rc_osc *osc = to_clk_slow_rc_osc(hw);

	return !!(readl(osc->sckcr) & AT91_SCKC_RCEN);
	}

	static const struct clk_ops slow_rc_osc_ops = {
	.prepare = clk_slow_rc_osc_prepare,
	.unprepare = clk_slow_rc_osc_unprepare,
	.is_prepared = clk_slow_rc_osc_is_prepared,
	.recalc_rate = clk_slow_rc_osc_recalc_rate,
	.recalc_accuracy = clk_slow_rc_osc_recalc_accuracy,
	};

	static struct clk * __init
	at91_clk_register_slow_rc_osc(void __iomem *sckcr,
	const char *name,
	unsigned long frequency,
	unsigned long accuracy,
	unsigned long startup)
	{
	struct clk_slow_rc_osc *osc;
	struct clk *clk = NULL;
	struct clk_init_data init;

	if (!sckcr \|\| !name)
	return ERR_PTR(-EINVAL);

	osc = kzalloc(sizeof(*osc), GFP_KERNEL);
	if (!osc)
	return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &slow_rc_osc_ops;
	init.parent_names = NULL;
	init.num_parents = 0;
	init.flags = CLK_IS_ROOT \| CLK_IGNORE_UNUSED;

	osc->hw.init = &init;
	osc->sckcr = sckcr;
	osc->frequency = frequency;
	osc->accuracy = accuracy;
	osc->startup_usec = startup;

	clk = clk_register(NULL, &osc->hw);
	if (IS_ERR(clk))
	kfree(osc);

	return clk;
	}

	void __init of_at91sam9x5_clk_slow_rc_osc_setup(struct device_node *np,
	void __iomem *sckcr)
	{
	struct clk *clk;
	u32 frequency = 0;
	u32 accuracy = 0;
	u32 startup = 0;
	const char *name = np->name;

	of_property_read_string(np, "clock-output-names", &name);
	of_property_read_u32(np, "clock-frequency", &frequency);
	of_property_read_u32(np, "clock-accuracy", &accuracy);
	of_property_read_u32(np, "atmel,startup-time-usec", &startup);

	clk = at91_clk_register_slow_rc_osc(sckcr, name, frequency, accuracy,
	startup);
	if (IS_ERR(clk))
	return;

	of_clk_add_provider(np, of_clk_src_simple_get, clk);
	}

	static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index)
	{
	struct clk_sam9x5_slow *slowck = to_clk_sam9x5_slow(hw);
	void __iomem *sckcr = slowck->sckcr;
	u32 tmp;

	if (index > 1)
	return -EINVAL;

	tmp = readl(sckcr);

	if ((!index && !(tmp & AT91_SCKC_OSCSEL)) \|\|
	(index && (tmp & AT91_SCKC_OSCSEL)))
	return 0;

	if (index)
	tmp \|= AT91_SCKC_OSCSEL;
	else
	tmp &= ~AT91_SCKC_OSCSEL;

	writel(tmp, sckcr);

	usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);

	return 0;
	}

	static u8 clk_sam9x5_slow_get_parent(struct clk_hw *hw)
	{
	struct clk_sam9x5_slow *slowck = to_clk_sam9x5_slow(hw);

	return !!(readl(slowck->sckcr) & AT91_SCKC_OSCSEL);
	}

	static const struct clk_ops sam9x5_slow_ops = {
	.set_parent = clk_sam9x5_slow_set_parent,
	.get_parent = clk_sam9x5_slow_get_parent,
	};

	static struct clk * __init
	at91_clk_register_sam9x5_slow(void __iomem *sckcr,
	const char *name,
	const char **parent_names,
	int num_parents)
	{
	struct clk_sam9x5_slow *slowck;
	struct clk *clk = NULL;
	struct clk_init_data init;

	if (!sckcr \|\| !name \|\| !parent_names \|\| !num_parents)
	return ERR_PTR(-EINVAL);

	slowck = kzalloc(sizeof(*slowck), GFP_KERNEL);
	if (!slowck)
	return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &sam9x5_slow_ops;
	init.parent_names = parent_names;
	init.num_parents = num_parents;
	init.flags = 0;

	slowck->hw.init = &init;
	slowck->sckcr = sckcr;
	slowck->parent = !!(readl(sckcr) & AT91_SCKC_OSCSEL);

	clk = clk_register(NULL, &slowck->hw);
	if (IS_ERR(clk))
	kfree(slowck);
	else
	slow_clk = clk;

	return clk;
	}

	void __init of_at91sam9x5_clk_slow_setup(struct device_node *np,
	void __iomem *sckcr)
	{
	struct clk *clk;
	const char *parent_names[2];
	int num_parents;
	const char *name = np->name;
	int i;

	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
	if (num_parents <= 0 \|\| num_parents > 2)
	return;

	for (i = 0; i < num_parents; ++i) {
	parent_names[i] = of_clk_get_parent_name(np, i);
	if (!parent_names[i])
	return;
	}

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

	clk = at91_clk_register_sam9x5_slow(sckcr, name, parent_names,
	num_parents);
	if (IS_ERR(clk))
	return;

	of_clk_add_provider(np, of_clk_src_simple_get, clk);
	}

	static u8 clk_sam9260_slow_get_parent(struct clk_hw *hw)
	{
	struct clk_sam9260_slow *slowck = to_clk_sam9260_slow(hw);

	return !!(pmc_read(slowck->pmc, AT91_PMC_SR) & AT91_PMC_OSCSEL);
	}

	static const struct clk_ops sam9260_slow_ops = {
	.get_parent = clk_sam9260_slow_get_parent,
	};

	static struct clk * __init
	at91_clk_register_sam9260_slow(struct at91_pmc *pmc,
	const char *name,
	const char **parent_names,
	int num_parents)
	{
	struct clk_sam9260_slow *slowck;
	struct clk *clk = NULL;
	struct clk_init_data init;

	if (!pmc \|\| !name)
	return ERR_PTR(-EINVAL);

	if (!parent_names \|\| !num_parents)
	return ERR_PTR(-EINVAL);

	slowck = kzalloc(sizeof(*slowck), GFP_KERNEL);
	if (!slowck)
	return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &sam9260_slow_ops;
	init.parent_names = parent_names;
	init.num_parents = num_parents;
	init.flags = 0;

	slowck->hw.init = &init;
	slowck->pmc = pmc;

	clk = clk_register(NULL, &slowck->hw);
	if (IS_ERR(clk))
	kfree(slowck);
	else
	slow_clk = clk;

	return clk;
	}

	void __init of_at91sam9260_clk_slow_setup(struct device_node *np,
	struct at91_pmc *pmc)
	{
	struct clk *clk;
	const char *parent_names[2];
	int num_parents;
	const char *name = np->name;
	int i;

	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
	if (num_parents != 2)
	return;

	for (i = 0; i < num_parents; ++i) {
	parent_names[i] = of_clk_get_parent_name(np, i);
	if (!parent_names[i])
	return;
	}

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

	clk = at91_clk_register_sam9260_slow(pmc, name, parent_names,
	num_parents);
	if (IS_ERR(clk))
	return;

	of_clk_add_provider(np, of_clk_src_simple_get, clk);
	}

	/*
	* FIXME: All slow clk users are not properly claiming it (get + prepare +
	* enable) before using it.
	* If all users properly claiming this clock decide that they don't need it
	* anymore (or are removed), it is disabled while faulty users are still
	* requiring it, and the system hangs.
	* Prevent this clock from being disabled until all users are properly
	* requesting it.
	* Once this is done we should remove this function and the slow_clk variable.
	*/
	static int __init of_at91_clk_slow_retain(void)
	{
	if (!slow_clk)
	return 0;

	__clk_get(slow_clk);
	clk_prepare_enable(slow_clk);

	return 0;
	}
	arch_initcall(of_at91_clk_slow_retain);