drivers/cpufreq/spear-cpufreq.c - linux - Git at Google

 /*
  * drivers/cpufreq/spear-cpufreq.c
  *
  * CPU Frequency Scaling for SPEAr platform
  *
  * Copyright (C) 2012 ST Microelectronics
  * Deepak Sikri <deepak.sikri@st.com>
  *
  * This file is licensed under the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any
  * warranty of any kind, whether express or implied.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/clk.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/types.h>

 /* SPEAr CPUFreq driver data structure */
 static struct {
 	struct clk *clk;
 	unsigned int transition_latency;
 	struct cpufreq_frequency_table *freq_tbl;
 	u32 cnt;
 } spear_cpufreq;

 static int spear_cpufreq_verify(struct cpufreq_policy *policy)
 {
 	return cpufreq_frequency_table_verify(policy, spear_cpufreq.freq_tbl);
 }

 static unsigned int spear_cpufreq_get(unsigned int cpu)
 {
 	return clk_get_rate(spear_cpufreq.clk) / 1000;
 }

 static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq)
 {
 	struct clk *sys_pclk;
 	int pclk;
 	/*
 	 * In SPEAr1340, cpu clk's parent sys clk can take input from
 	 * following sources
 	 */
 	const char *sys_clk_src[] = {
 		"sys_syn_clk",
 		"pll1_clk",
 		"pll2_clk",
 		"pll3_clk",
 	};

 	/*
 	 * As sys clk can have multiple source with their own range
 	 * limitation so we choose possible sources accordingly
 	 */
 	if (newfreq <= 300000000)
 		pclk = 0; /* src is sys_syn_clk */
 	else if (newfreq > 300000000 && newfreq <= 500000000)
 		pclk = 3; /* src is pll3_clk */
 	else if (newfreq == 600000000)
 		pclk = 1; /* src is pll1_clk */
 	else
 		return ERR_PTR(-EINVAL);

 	/* Get parent to sys clock */
 	sys_pclk = clk_get(NULL, sys_clk_src[pclk]);
 	if (IS_ERR(sys_pclk))
 		pr_err("Failed to get %s clock\n", sys_clk_src[pclk]);

 	return sys_pclk;
 }

 /*
  * In SPEAr1340, we cannot use newfreq directly because we need to actually
  * access a source clock (clk) which might not be ancestor of cpu at present.
  * Hence in SPEAr1340 we would operate on source clock directly before switching
  * cpu clock to it.
  */
 static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq)
 {
 	struct clk *sys_clk;
 	int ret = 0;

 	sys_clk = clk_get_parent(spear_cpufreq.clk);
 	if (IS_ERR(sys_clk)) {
 		pr_err("failed to get cpu's parent (sys) clock\n");
 		return PTR_ERR(sys_clk);
 	}

 	/* Set the rate of the source clock before changing the parent */
 	ret = clk_set_rate(sys_pclk, newfreq);
 	if (ret) {
 		pr_err("Failed to set sys clk rate to %lu\n", newfreq);
 		return ret;
 	}

 	ret = clk_set_parent(sys_clk, sys_pclk);
 	if (ret) {
 		pr_err("Failed to set sys clk parent\n");
 		return ret;
 	}

 	return 0;
 }

 static int spear_cpufreq_target(struct cpufreq_policy *policy,
 		unsigned int target_freq, unsigned int relation)
 {
 	struct cpufreq_freqs freqs;
 	unsigned long newfreq;
 	struct clk *srcclk;
 	int index, ret, mult = 1;

 	if (cpufreq_frequency_table_target(policy, spear_cpufreq.freq_tbl,
 				target_freq, relation, &index))
 		return -EINVAL;

 	freqs.old = spear_cpufreq_get(0);

 	newfreq = spear_cpufreq.freq_tbl[index].frequency * 1000;
 	if (of_machine_is_compatible("st,spear1340")) {
 		/*
 		 * SPEAr1340 is special in the sense that due to the possibility
 		 * of multiple clock sources for cpu clk's parent we can have
 		 * different clock source for different frequency of cpu clk.
 		 * Hence we need to choose one from amongst these possible clock
 		 * sources.
 		 */
 		srcclk = spear1340_cpu_get_possible_parent(newfreq);
 		if (IS_ERR(srcclk)) {
 			pr_err("Failed to get src clk\n");
 			return PTR_ERR(srcclk);
 		}

 		/* SPEAr1340: src clk is always 2 * intended cpu clk */
 		mult = 2;
 	} else {
 		/*
 		 * src clock to be altered is ancestor of cpu clock. Hence we
 		 * can directly work on cpu clk
 		 */
 		srcclk = spear_cpufreq.clk;
 	}

 	newfreq = clk_round_rate(srcclk, newfreq * mult);
 	if (newfreq < 0) {
 		pr_err("clk_round_rate failed for cpu src clock\n");
 		return newfreq;
 	}

 	freqs.new = newfreq / 1000;
 	freqs.new /= mult;

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

 	if (mult == 2)
 		ret = spear1340_set_cpu_rate(srcclk, newfreq);
 	else
 		ret = clk_set_rate(spear_cpufreq.clk, newfreq);

 	/* Get current rate after clk_set_rate, in case of failure */
 	if (ret) {
 		pr_err("CPU Freq: cpu clk_set_rate failed: %d\n", ret);
 		freqs.new = clk_get_rate(spear_cpufreq.clk) / 1000;
 	}

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 	return ret;
 }

 static int spear_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret;

 	ret = cpufreq_frequency_table_cpuinfo(policy, spear_cpufreq.freq_tbl);
 	if (ret) {
 		pr_err("cpufreq_frequency_table_cpuinfo() failed");
 		return ret;
 	}

 	cpufreq_frequency_table_get_attr(spear_cpufreq.freq_tbl, policy->cpu);
 	policy->cpuinfo.transition_latency = spear_cpufreq.transition_latency;
 	policy->cur = spear_cpufreq_get(0);

 	cpumask_setall(policy->cpus);

 	return 0;
 }

 static int spear_cpufreq_exit(struct cpufreq_policy *policy)
 {
 	cpufreq_frequency_table_put_attr(policy->cpu);
 	return 0;
 }

 static struct freq_attr *spear_cpufreq_attr[] = {
 	 &cpufreq_freq_attr_scaling_available_freqs,
 	 NULL,
 };

 static struct cpufreq_driver spear_cpufreq_driver = {
 	.name		= "cpufreq-spear",
 	.flags		= CPUFREQ_STICKY,
 	.verify		= spear_cpufreq_verify,
 	.target		= spear_cpufreq_target,
 	.get		= spear_cpufreq_get,
 	.init		= spear_cpufreq_init,
 	.exit		= spear_cpufreq_exit,
 	.attr		= spear_cpufreq_attr,
 };

 static int spear_cpufreq_driver_init(void)
 {
 	struct device_node *np;
 	const struct property *prop;
 	struct cpufreq_frequency_table *freq_tbl;
 	const __be32 *val;
 	int cnt, i, ret;

 	np = of_find_node_by_path("/cpus/cpu@0");
 	if (!np) {
 		pr_err("No cpu node found");
 		return -ENODEV;
 	}

 	if (of_property_read_u32(np, "clock-latency",
 				&spear_cpufreq.transition_latency))
 		spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;

 	prop = of_find_property(np, "cpufreq_tbl", NULL);
 	if (!prop || !prop->value) {
 		pr_err("Invalid cpufreq_tbl");
 		ret = -ENODEV;
 		goto out_put_node;
 	}

 	cnt = prop->length / sizeof(u32);
 	val = prop->value;

 	freq_tbl = kmalloc(sizeof(*freq_tbl) * (cnt + 1), GFP_KERNEL);
 	if (!freq_tbl) {
 		ret = -ENOMEM;
 		goto out_put_node;
 	}

 	for (i = 0; i < cnt; i++) {
 		freq_tbl[i].driver_data = i;
 		freq_tbl[i].frequency = be32_to_cpup(val++);
 	}

 	freq_tbl[i].driver_data = i;
 	freq_tbl[i].frequency = CPUFREQ_TABLE_END;

 	spear_cpufreq.freq_tbl = freq_tbl;

 	of_node_put(np);

 	spear_cpufreq.clk = clk_get(NULL, "cpu_clk");
 	if (IS_ERR(spear_cpufreq.clk)) {
 		pr_err("Unable to get CPU clock\n");
 		ret = PTR_ERR(spear_cpufreq.clk);
 		goto out_put_mem;
 	}

 	ret = cpufreq_register_driver(&spear_cpufreq_driver);
 	if (!ret)
 		return 0;

 	pr_err("failed register driver: %d\n", ret);
 	clk_put(spear_cpufreq.clk);

 out_put_mem:
 	kfree(freq_tbl);
 	return ret;

 out_put_node:
 	of_node_put(np);
 	return ret;
 }
 late_initcall(spear_cpufreq_driver_init);

 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
 MODULE_DESCRIPTION("SPEAr CPUFreq driver");
 MODULE_LICENSE("GPL");
	/*
	* drivers/cpufreq/spear-cpufreq.c
	*
	* CPU Frequency Scaling for SPEAr platform
	*
	* Copyright (C) 2012 ST Microelectronics
	* Deepak Sikri <deepak.sikri@st.com>
	*
	* This file is licensed under the terms of the GNU General Public
	* License version 2. This program is licensed "as is" without any
	* warranty of any kind, whether express or implied.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/clk.h>
	#include <linux/cpufreq.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/slab.h>
	#include <linux/types.h>

	/* SPEAr CPUFreq driver data structure */
	static struct {
	struct clk *clk;
	unsigned int transition_latency;
	struct cpufreq_frequency_table *freq_tbl;
	u32 cnt;
	} spear_cpufreq;

	static int spear_cpufreq_verify(struct cpufreq_policy *policy)
	{
	return cpufreq_frequency_table_verify(policy, spear_cpufreq.freq_tbl);
	}

	static unsigned int spear_cpufreq_get(unsigned int cpu)
	{
	return clk_get_rate(spear_cpufreq.clk) / 1000;
	}

	static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq)
	{
	struct clk *sys_pclk;
	int pclk;
	/*
	* In SPEAr1340, cpu clk's parent sys clk can take input from
	* following sources
	*/
	const char *sys_clk_src[] = {
	"sys_syn_clk",
	"pll1_clk",
	"pll2_clk",
	"pll3_clk",
	};

	/*
	* As sys clk can have multiple source with their own range
	* limitation so we choose possible sources accordingly
	*/
	if (newfreq <= 300000000)
	pclk = 0; /* src is sys_syn_clk */
	else if (newfreq > 300000000 && newfreq <= 500000000)
	pclk = 3; /* src is pll3_clk */
	else if (newfreq == 600000000)
	pclk = 1; /* src is pll1_clk */
	else
	return ERR_PTR(-EINVAL);

	/* Get parent to sys clock */
	sys_pclk = clk_get(NULL, sys_clk_src[pclk]);
	if (IS_ERR(sys_pclk))
	pr_err("Failed to get %s clock\n", sys_clk_src[pclk]);

	return sys_pclk;
	}

	/*
	* In SPEAr1340, we cannot use newfreq directly because we need to actually
	* access a source clock (clk) which might not be ancestor of cpu at present.
	* Hence in SPEAr1340 we would operate on source clock directly before switching
	* cpu clock to it.
	*/
	static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq)
	{
	struct clk *sys_clk;
	int ret = 0;

	sys_clk = clk_get_parent(spear_cpufreq.clk);
	if (IS_ERR(sys_clk)) {
	pr_err("failed to get cpu's parent (sys) clock\n");
	return PTR_ERR(sys_clk);
	}

	/* Set the rate of the source clock before changing the parent */
	ret = clk_set_rate(sys_pclk, newfreq);
	if (ret) {
	pr_err("Failed to set sys clk rate to %lu\n", newfreq);
	return ret;
	}

	ret = clk_set_parent(sys_clk, sys_pclk);
	if (ret) {
	pr_err("Failed to set sys clk parent\n");
	return ret;
	}

	return 0;
	}

	static int spear_cpufreq_target(struct cpufreq_policy *policy,
	unsigned int target_freq, unsigned int relation)
	{
	struct cpufreq_freqs freqs;
	unsigned long newfreq;
	struct clk *srcclk;
	int index, ret, mult = 1;

	if (cpufreq_frequency_table_target(policy, spear_cpufreq.freq_tbl,
	target_freq, relation, &index))
	return -EINVAL;

	freqs.old = spear_cpufreq_get(0);

	newfreq = spear_cpufreq.freq_tbl[index].frequency * 1000;
	if (of_machine_is_compatible("st,spear1340")) {
	/*
	* SPEAr1340 is special in the sense that due to the possibility
	* of multiple clock sources for cpu clk's parent we can have
	* different clock source for different frequency of cpu clk.
	* Hence we need to choose one from amongst these possible clock
	* sources.
	*/
	srcclk = spear1340_cpu_get_possible_parent(newfreq);
	if (IS_ERR(srcclk)) {
	pr_err("Failed to get src clk\n");
	return PTR_ERR(srcclk);
	}

	/* SPEAr1340: src clk is always 2 * intended cpu clk */
	mult = 2;
	} else {
	/*
	* src clock to be altered is ancestor of cpu clock. Hence we
	* can directly work on cpu clk
	*/
	srcclk = spear_cpufreq.clk;
	}

	newfreq = clk_round_rate(srcclk, newfreq * mult);
	if (newfreq < 0) {
	pr_err("clk_round_rate failed for cpu src clock\n");
	return newfreq;
	}

	freqs.new = newfreq / 1000;
	freqs.new /= mult;

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

	if (mult == 2)
	ret = spear1340_set_cpu_rate(srcclk, newfreq);
	else
	ret = clk_set_rate(spear_cpufreq.clk, newfreq);

	/* Get current rate after clk_set_rate, in case of failure */
	if (ret) {
	pr_err("CPU Freq: cpu clk_set_rate failed: %d\n", ret);
	freqs.new = clk_get_rate(spear_cpufreq.clk) / 1000;
	}

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
	return ret;
	}

	static int spear_cpufreq_init(struct cpufreq_policy *policy)
	{
	int ret;

	ret = cpufreq_frequency_table_cpuinfo(policy, spear_cpufreq.freq_tbl);
	if (ret) {
	pr_err("cpufreq_frequency_table_cpuinfo() failed");
	return ret;
	}

	cpufreq_frequency_table_get_attr(spear_cpufreq.freq_tbl, policy->cpu);
	policy->cpuinfo.transition_latency = spear_cpufreq.transition_latency;
	policy->cur = spear_cpufreq_get(0);

	cpumask_setall(policy->cpus);

	return 0;
	}

	static int spear_cpufreq_exit(struct cpufreq_policy *policy)
	{
	cpufreq_frequency_table_put_attr(policy->cpu);
	return 0;
	}

	static struct freq_attr *spear_cpufreq_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	NULL,
	};

	static struct cpufreq_driver spear_cpufreq_driver = {
	.name = "cpufreq-spear",
	.flags = CPUFREQ_STICKY,
	.verify = spear_cpufreq_verify,
	.target = spear_cpufreq_target,
	.get = spear_cpufreq_get,
	.init = spear_cpufreq_init,
	.exit = spear_cpufreq_exit,
	.attr = spear_cpufreq_attr,
	};

	static int spear_cpufreq_driver_init(void)
	{
	struct device_node *np;
	const struct property *prop;
	struct cpufreq_frequency_table *freq_tbl;
	const __be32 *val;
	int cnt, i, ret;

	np = of_find_node_by_path("/cpus/cpu@0");
	if (!np) {
	pr_err("No cpu node found");
	return -ENODEV;
	}

	if (of_property_read_u32(np, "clock-latency",
	&spear_cpufreq.transition_latency))
	spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;

	prop = of_find_property(np, "cpufreq_tbl", NULL);
	if (!prop \|\| !prop->value) {
	pr_err("Invalid cpufreq_tbl");
	ret = -ENODEV;
	goto out_put_node;
	}

	cnt = prop->length / sizeof(u32);
	val = prop->value;

	freq_tbl = kmalloc(sizeof(freq_tbl) (cnt + 1), GFP_KERNEL);
	if (!freq_tbl) {
	ret = -ENOMEM;
	goto out_put_node;
	}

	for (i = 0; i < cnt; i++) {
	freq_tbl[i].driver_data = i;
	freq_tbl[i].frequency = be32_to_cpup(val++);
	}

	freq_tbl[i].driver_data = i;
	freq_tbl[i].frequency = CPUFREQ_TABLE_END;

	spear_cpufreq.freq_tbl = freq_tbl;

	of_node_put(np);

	spear_cpufreq.clk = clk_get(NULL, "cpu_clk");
	if (IS_ERR(spear_cpufreq.clk)) {
	pr_err("Unable to get CPU clock\n");
	ret = PTR_ERR(spear_cpufreq.clk);
	goto out_put_mem;
	}

	ret = cpufreq_register_driver(&spear_cpufreq_driver);
	if (!ret)
	return 0;

	pr_err("failed register driver: %d\n", ret);
	clk_put(spear_cpufreq.clk);

	out_put_mem:
	kfree(freq_tbl);
	return ret;

	out_put_node:
	of_node_put(np);
	return ret;
	}
	late_initcall(spear_cpufreq_driver_init);

	MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
	MODULE_DESCRIPTION("SPEAr CPUFreq driver");
	MODULE_LICENSE("GPL");