Initial import

1 files changed, 491 insertions, 0 deletions

diff --git a/drivers/cpufreq/s3c2416-cpufreq.c b/drivers/cpufreq/s3c2416-cpufreq.c
new file mode 100644
index 000000000..d6d425773
--- /dev/null
+++ b/drivers/cpufreq/s3c2416-cpufreq.c
@@ -0,0 +1,491 @@
+/*
+ * S3C2416/2450 CPUfreq Support
+ *
+ * Copyright 2011 Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on s3c64xx_cpufreq.c
+ *
+ * Copyright 2009 Wolfson Microelectronics plc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/regulator/consumer.h>
+#include <linux/reboot.h>
+#include <linux/module.h>
+
+static DEFINE_MUTEX(cpufreq_lock);
+
+struct s3c2416_data {
+	struct clk *armdiv;
+	struct clk *armclk;
+	struct clk *hclk;
+
+	unsigned long regulator_latency;
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	struct regulator *vddarm;
+#endif
+
+	struct cpufreq_frequency_table *freq_table;
+
+	bool is_dvs;
+	bool disable_dvs;
+};
+
+static struct s3c2416_data s3c2416_cpufreq;
+
+struct s3c2416_dvfs {
+	unsigned int vddarm_min;
+	unsigned int vddarm_max;
+};
+
+/* pseudo-frequency for dvs mode */
+#define FREQ_DVS	132333
+
+/* frequency to sleep and reboot in
+ * it's essential to leave dvs, as some boards do not reconfigure the
+ * regulator on reboot
+ */
+#define FREQ_SLEEP	133333
+
+/* Sources for the ARMCLK */
+#define SOURCE_HCLK	0
+#define SOURCE_ARMDIV	1
+
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+/* S3C2416 only supports changing the voltage in the dvs-mode.
+ * Voltages down to 1.0V seem to work, so we take what the regulator
+ * can get us.
+ */
+static struct s3c2416_dvfs s3c2416_dvfs_table[] = {
+	[SOURCE_HCLK] = {  950000, 1250000 },
+	[SOURCE_ARMDIV] = { 1250000, 1350000 },
+};
+#endif
+
+static struct cpufreq_frequency_table s3c2416_freq_table[] = {
+	{ 0, SOURCE_HCLK, FREQ_DVS },
+	{ 0, SOURCE_ARMDIV, 133333 },
+	{ 0, SOURCE_ARMDIV, 266666 },
+	{ 0, SOURCE_ARMDIV, 400000 },
+	{ 0, 0, CPUFREQ_TABLE_END },
+};
+
+static struct cpufreq_frequency_table s3c2450_freq_table[] = {
+	{ 0, SOURCE_HCLK, FREQ_DVS },
+	{ 0, SOURCE_ARMDIV, 133500 },
+	{ 0, SOURCE_ARMDIV, 267000 },
+	{ 0, SOURCE_ARMDIV, 534000 },
+	{ 0, 0, CPUFREQ_TABLE_END },
+};
+
+static unsigned int s3c2416_cpufreq_get_speed(unsigned int cpu)
+{
+	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
+
+	if (cpu != 0)
+		return 0;
+
+	/* return our pseudo-frequency when in dvs mode */
+	if (s3c_freq->is_dvs)
+		return FREQ_DVS;
+
+	return clk_get_rate(s3c_freq->armclk) / 1000;
+}
+
+static int s3c2416_cpufreq_set_armdiv(struct s3c2416_data *s3c_freq,
+				      unsigned int freq)
+{
+	int ret;
+
+	if (clk_get_rate(s3c_freq->armdiv) / 1000 != freq) {
+		ret = clk_set_rate(s3c_freq->armdiv, freq * 1000);
+		if (ret < 0) {
+			pr_err("cpufreq: Failed to set armdiv rate %dkHz: %d\n",
+			       freq, ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int s3c2416_cpufreq_enter_dvs(struct s3c2416_data *s3c_freq, int idx)
+{
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	struct s3c2416_dvfs *dvfs;
+#endif
+	int ret;
+
+	if (s3c_freq->is_dvs) {
+		pr_debug("cpufreq: already in dvs mode, nothing to do\n");
+		return 0;
+	}
+
+	pr_debug("cpufreq: switching armclk to hclk (%lukHz)\n",
+		 clk_get_rate(s3c_freq->hclk) / 1000);
+	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->hclk);
+	if (ret < 0) {
+		pr_err("cpufreq: Failed to switch armclk to hclk: %d\n", ret);
+		return ret;
+	}
+
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	/* changing the core voltage is only allowed when in dvs mode */
+	if (s3c_freq->vddarm) {
+		dvfs = &s3c2416_dvfs_table[idx];
+
+		pr_debug("cpufreq: setting regulator to %d-%d\n",
+			 dvfs->vddarm_min, dvfs->vddarm_max);
+		ret = regulator_set_voltage(s3c_freq->vddarm,
+					    dvfs->vddarm_min,
+					    dvfs->vddarm_max);
+
+		/* when lowering the voltage failed, there is nothing to do */
+		if (ret != 0)
+			pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
+	}
+#endif
+
+	s3c_freq->is_dvs = 1;
+
+	return 0;
+}
+
+static int s3c2416_cpufreq_leave_dvs(struct s3c2416_data *s3c_freq, int idx)
+{
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	struct s3c2416_dvfs *dvfs;
+#endif
+	int ret;
+
+	if (!s3c_freq->is_dvs) {
+		pr_debug("cpufreq: not in dvs mode, so can't leave\n");
+		return 0;
+	}
+
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	if (s3c_freq->vddarm) {
+		dvfs = &s3c2416_dvfs_table[idx];
+
+		pr_debug("cpufreq: setting regulator to %d-%d\n",
+			 dvfs->vddarm_min, dvfs->vddarm_max);
+		ret = regulator_set_voltage(s3c_freq->vddarm,
+					    dvfs->vddarm_min,
+					    dvfs->vddarm_max);
+		if (ret != 0) {
+			pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
+			return ret;
+		}
+	}
+#endif
+
+	/* force armdiv to hclk frequency for transition from dvs*/
+	if (clk_get_rate(s3c_freq->armdiv) > clk_get_rate(s3c_freq->hclk)) {
+		pr_debug("cpufreq: force armdiv to hclk frequency (%lukHz)\n",
+			 clk_get_rate(s3c_freq->hclk) / 1000);
+		ret = s3c2416_cpufreq_set_armdiv(s3c_freq,
+					clk_get_rate(s3c_freq->hclk) / 1000);
+		if (ret < 0) {
+			pr_err("cpufreq: Failed to set the armdiv to %lukHz: %d\n",
+			       clk_get_rate(s3c_freq->hclk) / 1000, ret);
+			return ret;
+		}
+	}
+
+	pr_debug("cpufreq: switching armclk parent to armdiv (%lukHz)\n",
+			clk_get_rate(s3c_freq->armdiv) / 1000);
+
+	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->armdiv);
+	if (ret < 0) {
+		pr_err("cpufreq: Failed to switch armclk clock parent to armdiv: %d\n",
+		       ret);
+		return ret;
+	}
+
+	s3c_freq->is_dvs = 0;
+
+	return 0;
+}
+
+static int s3c2416_cpufreq_set_target(struct cpufreq_policy *policy,
+				      unsigned int index)
+{
+	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
+	unsigned int new_freq;
+	int idx, ret, to_dvs = 0;
+
+	mutex_lock(&cpufreq_lock);
+
+	idx = s3c_freq->freq_table[index].driver_data;
+
+	if (idx == SOURCE_HCLK)
+		to_dvs = 1;
+
+	/* switching to dvs when it's not allowed */
+	if (to_dvs && s3c_freq->disable_dvs) {
+		pr_debug("cpufreq: entering dvs mode not allowed\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* When leavin dvs mode, always switch the armdiv to the hclk rate
+	 * The S3C2416 has stability issues when switching directly to
+	 * higher frequencies.
+	 */
+	new_freq = (s3c_freq->is_dvs && !to_dvs)
+				? clk_get_rate(s3c_freq->hclk) / 1000
+				: s3c_freq->freq_table[index].frequency;
+
+	if (to_dvs) {
+		pr_debug("cpufreq: enter dvs\n");
+		ret = s3c2416_cpufreq_enter_dvs(s3c_freq, idx);
+	} else if (s3c_freq->is_dvs) {
+		pr_debug("cpufreq: leave dvs\n");
+		ret = s3c2416_cpufreq_leave_dvs(s3c_freq, idx);
+	} else {
+		pr_debug("cpufreq: change armdiv to %dkHz\n", new_freq);
+		ret = s3c2416_cpufreq_set_armdiv(s3c_freq, new_freq);
+	}
+
+out:
+	mutex_unlock(&cpufreq_lock);
+
+	return ret;
+}
+
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+static void s3c2416_cpufreq_cfg_regulator(struct s3c2416_data *s3c_freq)
+{
+	int count, v, i, found;
+	struct cpufreq_frequency_table *pos;
+	struct s3c2416_dvfs *dvfs;
+
+	count = regulator_count_voltages(s3c_freq->vddarm);
+	if (count < 0) {
+		pr_err("cpufreq: Unable to check supported voltages\n");
+		return;
+	}
+
+	if (!count)
+		goto out;
+
+	cpufreq_for_each_valid_entry(pos, s3c_freq->freq_table) {
+		dvfs = &s3c2416_dvfs_table[pos->driver_data];
+		found = 0;
+
+		/* Check only the min-voltage, more is always ok on S3C2416 */
+		for (i = 0; i < count; i++) {
+			v = regulator_list_voltage(s3c_freq->vddarm, i);
+			if (v >= dvfs->vddarm_min)
+				found = 1;
+		}
+
+		if (!found) {
+			pr_debug("cpufreq: %dkHz unsupported by regulator\n",
+				 pos->frequency);
+			pos->frequency = CPUFREQ_ENTRY_INVALID;
+		}
+	}
+
+out:
+	/* Guessed */
+	s3c_freq->regulator_latency = 1 * 1000 * 1000;
+}
+#endif
+
+static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this,
+					       unsigned long event, void *ptr)
+{
+	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
+	int ret;
+
+	mutex_lock(&cpufreq_lock);
+
+	/* disable further changes */
+	s3c_freq->disable_dvs = 1;
+
+	mutex_unlock(&cpufreq_lock);
+
+	/* some boards don't reconfigure the regulator on reboot, which
+	 * could lead to undervolting the cpu when the clock is reset.
+	 * Therefore we always leave the DVS mode on reboot.
+	 */
+	if (s3c_freq->is_dvs) {
+		pr_debug("cpufreq: leave dvs on reboot\n");
+		ret = cpufreq_driver_target(cpufreq_cpu_get(0), FREQ_SLEEP, 0);
+		if (ret < 0)
+			return NOTIFY_BAD;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block s3c2416_cpufreq_reboot_notifier = {
+	.notifier_call = s3c2416_cpufreq_reboot_notifier_evt,
+};
+
+static int s3c2416_cpufreq_driver_init(struct cpufreq_policy *policy)
+{
+	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
+	struct cpufreq_frequency_table *pos;
+	struct clk *msysclk;
+	unsigned long rate;
+	int ret;
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	msysclk = clk_get(NULL, "msysclk");
+	if (IS_ERR(msysclk)) {
+		ret = PTR_ERR(msysclk);
+		pr_err("cpufreq: Unable to obtain msysclk: %d\n", ret);
+		return ret;
+	}
+
+	/*
+	 * S3C2416 and S3C2450 share the same processor-ID and also provide no
+	 * other means to distinguish them other than through the rate of
+	 * msysclk. On S3C2416 msysclk runs at 800MHz and on S3C2450 at 533MHz.
+	 */
+	rate = clk_get_rate(msysclk);
+	if (rate == 800 * 1000 * 1000) {
+		pr_info("cpufreq: msysclk running at %lukHz, using S3C2416 frequency table\n",
+			rate / 1000);
+		s3c_freq->freq_table = s3c2416_freq_table;
+		policy->cpuinfo.max_freq = 400000;
+	} else if (rate / 1000 == 534000) {
+		pr_info("cpufreq: msysclk running at %lukHz, using S3C2450 frequency table\n",
+			rate / 1000);
+		s3c_freq->freq_table = s3c2450_freq_table;
+		policy->cpuinfo.max_freq = 534000;
+	}
+
+	/* not needed anymore */
+	clk_put(msysclk);
+
+	if (s3c_freq->freq_table == NULL) {
+		pr_err("cpufreq: No frequency information for this CPU, msysclk at %lukHz\n",
+		       rate / 1000);
+		return -ENODEV;
+	}
+
+	s3c_freq->is_dvs = 0;
+
+	s3c_freq->armdiv = clk_get(NULL, "armdiv");
+	if (IS_ERR(s3c_freq->armdiv)) {
+		ret = PTR_ERR(s3c_freq->armdiv);
+		pr_err("cpufreq: Unable to obtain ARMDIV: %d\n", ret);
+		return ret;
+	}
+
+	s3c_freq->hclk = clk_get(NULL, "hclk");
+	if (IS_ERR(s3c_freq->hclk)) {
+		ret = PTR_ERR(s3c_freq->hclk);
+		pr_err("cpufreq: Unable to obtain HCLK: %d\n", ret);
+		goto err_hclk;
+	}
+
+	/* chech hclk rate, we only support the common 133MHz for now
+	 * hclk could also run at 66MHz, but this not often used
+	 */
+	rate = clk_get_rate(s3c_freq->hclk);
+	if (rate < 133 * 1000 * 1000) {
+		pr_err("cpufreq: HCLK not at 133MHz\n");
+		clk_put(s3c_freq->hclk);
+		ret = -EINVAL;
+		goto err_armclk;
+	}
+
+	s3c_freq->armclk = clk_get(NULL, "armclk");
+	if (IS_ERR(s3c_freq->armclk)) {
+		ret = PTR_ERR(s3c_freq->armclk);
+		pr_err("cpufreq: Unable to obtain ARMCLK: %d\n", ret);
+		goto err_armclk;
+	}
+
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	s3c_freq->vddarm = regulator_get(NULL, "vddarm");
+	if (IS_ERR(s3c_freq->vddarm)) {
+		ret = PTR_ERR(s3c_freq->vddarm);
+		pr_err("cpufreq: Failed to obtain VDDARM: %d\n", ret);
+		goto err_vddarm;
+	}
+
+	s3c2416_cpufreq_cfg_regulator(s3c_freq);
+#else
+	s3c_freq->regulator_latency = 0;
+#endif
+
+	cpufreq_for_each_entry(pos, s3c_freq->freq_table) {
+		/* special handling for dvs mode */
+		if (pos->driver_data == 0) {
+			if (!s3c_freq->hclk) {
+				pr_debug("cpufreq: %dkHz unsupported as it would need unavailable dvs mode\n",
+					 pos->frequency);
+				pos->frequency = CPUFREQ_ENTRY_INVALID;
+			} else {
+				continue;
+			}
+		}
+
+		/* Check for frequencies we can generate */
+		rate = clk_round_rate(s3c_freq->armdiv,
+				      pos->frequency * 1000);
+		rate /= 1000;
+		if (rate != pos->frequency) {
+			pr_debug("cpufreq: %dkHz unsupported by clock (clk_round_rate return %lu)\n",
+				pos->frequency, rate);
+			pos->frequency = CPUFREQ_ENTRY_INVALID;
+		}
+	}
+
+	/* Datasheet says PLL stabalisation time must be at least 300us,
+	 * so but add some fudge. (reference in LOCKCON0 register description)
+	 */
+	ret = cpufreq_generic_init(policy, s3c_freq->freq_table,
+			(500 * 1000) + s3c_freq->regulator_latency);
+	if (ret)
+		goto err_freq_table;
+
+	register_reboot_notifier(&s3c2416_cpufreq_reboot_notifier);
+
+	return 0;
+
+err_freq_table:
+#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
+	regulator_put(s3c_freq->vddarm);
+err_vddarm:
+#endif
+	clk_put(s3c_freq->armclk);
+err_armclk:
+	clk_put(s3c_freq->hclk);
+err_hclk:
+	clk_put(s3c_freq->armdiv);
+
+	return ret;
+}
+
+static struct cpufreq_driver s3c2416_cpufreq_driver = {
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= s3c2416_cpufreq_set_target,
+	.get		= s3c2416_cpufreq_get_speed,
+	.init		= s3c2416_cpufreq_driver_init,
+	.name		= "s3c2416",
+	.attr		= cpufreq_generic_attr,
+};
+
+static int __init s3c2416_cpufreq_init(void)
+{
+	return cpufreq_register_driver(&s3c2416_cpufreq_driver);
+}
+module_init(s3c2416_cpufreq_init);