ARM: tegra: dvfs: Support persistent alt frequencies

Existing interface to dvfs alternative frequencies combined enable
control with alternative ladder installation. Hence, the only way to
switch back to primary frequencies was to de-install alternative ones.

This commit provided separate install and enable interfaces, so that
alternative ladder can be installed once, and then enabled/disabled
under client control. Also made sure alternative voltage-frequency
mapping results in lower voltage at the same frequency (this was an
implicit assumption of alternative frequencies support - now it is
enforced explicitly).

Bug 1397158

Change-Id: I4663602d1882f72156e02590f41ff04e7e69fbf8
Signed-off-by: Alex Frid <afrid@nvidia.com>
Reviewed-on: http://git-master/r/333090
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>

3 files changed, 88 insertions, 5 deletions

diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index 2678315877f5..ca18a8c65e5a 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -1694,6 +1694,20 @@ static const struct file_operations possible_rates_fops = {
 	.release	= single_release,
 };
 
+static int use_alt_freq_get(void *data, u64 *val)
+{
+	struct clk *c = (struct clk *)data;
+	*val = c->dvfs->use_alt_freqs;
+	return 0;
+}
+static int use_alt_freq_set(void *data, u64 val)
+{
+	struct clk *c = (struct clk *)data;
+	return tegra_dvfs_use_alt_freqs_on_clk(c, val);
+}
+DEFINE_SIMPLE_ATTRIBUTE(use_alt_freq_fops,
+			use_alt_freq_get, use_alt_freq_set, "%llu\n");
+
 static int clk_debugfs_register_one(struct clk *c)
 {
 	struct dentry *d;
@@ -1762,6 +1776,13 @@ static int clk_debugfs_register_one(struct clk *c)
 			goto err_out;
 	}
 
+	if (c->dvfs) {
+		d = debugfs_create_file("use_alt_freq", S_IRUGO | S_IWUSR,
+			c->dent, c, &use_alt_freq_fops);
+		if (!d)
+			goto err_out;
+	}
+
 	return 0;
 
 err_out:
diff --git a/arch/arm/mach-tegra/dvfs.c b/arch/arm/mach-tegra/dvfs.c
index 8fae879b4ca2..6a16a2fc8c98 100644
--- a/arch/arm/mach-tegra/dvfs.c
+++ b/arch/arm/mach-tegra/dvfs.c
@@ -559,7 +559,7 @@ static int dvfs_rail_connect_to_regulator(struct dvfs_rail *rail)
 
 static inline unsigned long *dvfs_get_freqs(struct dvfs *d)
 {
-	return d->alt_freqs ? : &d->freqs[0];
+	return d->alt_freqs && d->use_alt_freqs ? d->alt_freqs : &d->freqs[0];
 }
 
 static inline const int *dvfs_get_millivolts(struct dvfs *d, unsigned long rate)
@@ -647,6 +647,61 @@ __tegra_dvfs_set_rate(struct dvfs *d, unsigned long rate)
 	return ret;
 }
 
+/*
+ * Some clocks may have alternative frequency ladder that provides lower minimum
+ * voltage at the same rate (or complimentary: higher maximum rate at the same
+ * voltage). Interfaces below allows dvfs clients to install such ladder, and
+ * switch between primary and alternative frequencies in flight.
+ */
+static int alt_freqs_validate(struct dvfs *d, unsigned long *alt_freqs)
+{
+	int i;
+
+	if (alt_freqs) {
+		for (i = 0; i < d->num_freqs; i++) {
+			if (d->freqs[i] > alt_freqs[i]) {
+				pr_err("%s: Invalid alt freqs for %s\n",
+				       __func__, d->clk_name);
+				return -EINVAL;
+			}
+		}
+	}
+	return 0;
+}
+
+int tegra_dvfs_alt_freqs_install(struct dvfs *d, unsigned long *alt_freqs)
+{
+	int ret = 0;
+
+	mutex_lock(&dvfs_lock);
+
+	ret = alt_freqs_validate(d, alt_freqs);
+	if (!ret)
+		d->alt_freqs = alt_freqs;
+
+	mutex_unlock(&dvfs_lock);
+	return ret;
+}
+
+int tegra_dvfs_use_alt_freqs_on_clk(struct clk *c, bool use_alt_freq)
+{
+	int ret = -ENOENT;
+	struct dvfs *d = c->dvfs;
+
+	mutex_lock(&dvfs_lock);
+
+	if (d && d->alt_freqs) {
+		ret = 0;
+		if (d->use_alt_freqs != use_alt_freq) {
+			d->use_alt_freqs = use_alt_freq;
+			ret = __tegra_dvfs_set_rate(d, d->cur_rate);
+		}
+	}
+
+	mutex_unlock(&dvfs_lock);
+	return ret;
+}
+
 int tegra_dvfs_alt_freqs_set(struct dvfs *d, unsigned long *alt_freqs)
 {
 	int ret = 0;
@@ -654,8 +709,12 @@ int tegra_dvfs_alt_freqs_set(struct dvfs *d, unsigned long *alt_freqs)
 	mutex_lock(&dvfs_lock);
 
 	if (d->alt_freqs != alt_freqs) {
-		d->alt_freqs = alt_freqs;
-		ret = __tegra_dvfs_set_rate(d, d->cur_rate);
+		ret = alt_freqs_validate(d, alt_freqs);
+		if (!ret) {
+			d->use_alt_freqs = !!alt_freqs;
+			d->alt_freqs = alt_freqs;
+			ret = __tegra_dvfs_set_rate(d, d->cur_rate);
+		}
 	}
 
 	mutex_unlock(&dvfs_lock);
@@ -2046,7 +2105,8 @@ static int dvfs_table_show(struct seq_file *s, void *data)
 
 			seq_printf(s, "%-16s", d->clk_name);
 			for (i = 0; i < d->num_freqs; i++) {
-				unsigned int f = d->freqs[i]/100000;
+				unsigned long *freqs = dvfs_get_freqs(d);
+				unsigned int f = freqs[i]/100000;
 				seq_printf(s, " %4u.%u", f/10, f%10);
 			}
 			seq_printf(s, "\n");
diff --git a/arch/arm/mach-tegra/dvfs.h b/arch/arm/mach-tegra/dvfs.h
index aadf9668cb4b..bcb1f62fc086 100644
--- a/arch/arm/mach-tegra/dvfs.h
+++ b/arch/arm/mach-tegra/dvfs.h
@@ -144,7 +144,6 @@ struct dvfs {
 	/* Must be initialized before tegra_dvfs_init */
 	int freqs_mult;
 	unsigned long freqs[MAX_DVFS_FREQS];
-	unsigned long *alt_freqs;
 	const int *millivolts;
 	const int *peak_millivolts;
 	const int *dfll_millivolts;
@@ -161,6 +160,8 @@ struct dvfs {
 
 	int cur_millivolts;
 	unsigned long cur_rate;
+	unsigned long *alt_freqs;
+	bool use_alt_freqs;
 	struct list_head node;
 	struct list_head debug_node;
 	struct list_head reg_node;
@@ -250,6 +251,7 @@ int tegra_dvfs_predict_millivolts_dfll(struct clk *c, unsigned long rate);
 const int *tegra_dvfs_get_millivolts_pll(struct dvfs *d);
 
 int tegra_dvfs_override_core_cap_apply(int level);
+int tegra_dvfs_alt_freqs_install(struct dvfs *d, unsigned long *alt_freqs);
 int tegra_dvfs_alt_freqs_set(struct dvfs *d, unsigned long *alt_freqs);
 int tegra_cpu_dvfs_alter(int edp_thermal_index, const cpumask_t *cpus,
 			 bool before_clk_update, int cpu_event);