cpufreq: imx6q: correct VDDSOC/PU voltage scaling when cpufreq is changed

on i.MX6Q, cpu freq change need to follow below flows:

1. each setpoint has different VDDARM, VDDSOC/PU voltage, get the setpoint
   table from dts;
2. when cpu freq is scaling up, need to increase VDDSOC/PU voltage before
   VDDARM, if VDDPU is off, no need to change it;
3. when cpu freq is scaling down, need to decrease VDDARM voltage before
   VDDSOC/PU, if VDDPU is off, no need to change it;

normally dts will pass vddsoc/pu freq/volt info to kernel, if not, will
use fixed value for vddsoc/pu voltage setting.

Signed-off-by: Anson Huang <b20788@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 77 insertions, 29 deletions

diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index 4b3f18e5f36b..c29198fbc9b7 100644
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -35,6 +35,9 @@ static struct device *cpu_dev;
 static struct cpufreq_frequency_table *freq_table;
 static unsigned int transition_latency;
 
+static u32 *imx6_soc_volt;
+static u32 soc_opp_count;
+
 static unsigned int imx6q_get_speed(unsigned int cpu)
 {
         return clk_get_rate(arm_clk) / 1000;
@@ -69,23 +72,22 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
 
         /* scaling up?  scale voltage before frequency */
         if (new_freq > old_freq) {
+                ret = regulator_set_voltage_tol(pu_reg, imx6_soc_volt[index], 0);
+                if (ret) {
+                        dev_err(cpu_dev, "failed to scale vddpu up: %d\n", ret);
+                        return ret;
+                }
+                ret = regulator_set_voltage_tol(soc_reg, imx6_soc_volt[index], 0);
+                if (ret) {
+                        dev_err(cpu_dev, "failed to scale vddsoc up: %d\n", ret);
+                        return ret;
+                }
                 ret = regulator_set_voltage_tol(arm_reg, volt, 0);
                 if (ret) {
                         dev_err(cpu_dev,
                                 "failed to scale vddarm up: %d\n", ret);
                         return ret;
                 }
-
-                /*
-                 * Need to increase vddpu and vddsoc for safety
-                 * if we are about to run at 1.2 GHz.
-                 */
-                if (new_freq == FREQ_1P2_GHZ / 1000) {
-                        regulator_set_voltage_tol(pu_reg,
-                                        PU_SOC_VOLTAGE_HIGH, 0);
-                        regulator_set_voltage_tol(soc_reg,
-                                        PU_SOC_VOLTAGE_HIGH, 0);
-                }
         }
 
         /*
@@ -120,12 +122,15 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
                                  "failed to scale vddarm down: %d\n", ret);
                         ret = 0;
                 }
-
-                if (old_freq == FREQ_1P2_GHZ / 1000) {
-                        regulator_set_voltage_tol(pu_reg,
-                                        PU_SOC_VOLTAGE_NORMAL, 0);
-                        regulator_set_voltage_tol(soc_reg,
-                                        PU_SOC_VOLTAGE_NORMAL, 0);
+                ret = regulator_set_voltage_tol(soc_reg, imx6_soc_volt[index], 0);
+                if (ret) {
+                        dev_warn(cpu_dev, "failed to scale vddsoc down: %d\n", ret);
+                        ret = 0;
+                }
+                ret = regulator_set_voltage_tol(pu_reg, imx6_soc_volt[index], 0);
+                if (ret) {
+                        dev_warn(cpu_dev, "failed to scale vddpu down: %d\n", ret);
+                        ret = 0;
                 }
         }
 
@@ -153,6 +158,9 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
         struct dev_pm_opp *opp;
         unsigned long min_volt, max_volt;
         int num, ret;
+        const struct property *prop;
+        const __be32 *val;
+        u32 nr, i, j;
 
         cpu_dev = get_cpu_device(0);
         if (!cpu_dev) {
@@ -201,10 +209,62 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
                 goto put_node;
         }
 
+        /* Make imx6_soc_volt array's size same as arm opp number */
+        imx6_soc_volt = devm_kzalloc(cpu_dev, sizeof(*imx6_soc_volt) * num, GFP_KERNEL);
+        if (imx6_soc_volt == NULL) {
+                ret = -ENOMEM;
+                goto free_freq_table;
+        }
+
+        prop = of_find_property(np, "fsl,soc-operating-points", NULL);
+        if (!prop || !prop->value)
+                goto soc_opp_out;
+
+        /*
+         * Each OPP is a set of tuples consisting of frequency and
+         * voltage like <freq-kHz vol-uV>.
+         */
+        nr = prop->length / sizeof(u32);
+        if (nr % 2 || (nr / 2) < num)
+                goto soc_opp_out;
+
+        for (j = 0; j < num; j++) {
+                val = prop->value;
+                for (i = 0; i < nr / 2; i++) {
+                        unsigned long freq = be32_to_cpup(val++);
+                        unsigned long volt = be32_to_cpup(val++);
+                        if (freq_table[j].frequency == freq) {
+                                imx6_soc_volt[soc_opp_count++] = volt;
+                                break;
+                        }
+                }
+        }
+
+soc_opp_out:
+        /* use fixed soc opp volt if no valid soc opp info found in dtb */
+        if (soc_opp_count != num) {
+                dev_warn(cpu_dev, "can NOT find valid fsl,soc-operating-points property in dtb, use default value!\n");
+                for (j = 0; j < num; j++)
+                        imx6_soc_volt[j] = PU_SOC_VOLTAGE_NORMAL;
+                if (freq_table[num - 1].frequency * 1000 == FREQ_1P2_GHZ)
+                        imx6_soc_volt[num - 1] = PU_SOC_VOLTAGE_HIGH;
+        }
+
         if (of_property_read_u32(np, "clock-latency", &transition_latency))
                 transition_latency = CPUFREQ_ETERNAL;
 
         /*
+         * Calculate the ramp time for max voltage change in the
+         * VDDSOC and VDDPU regulators.
+         */
+        ret = regulator_set_voltage_time(soc_reg, imx6_soc_volt[0], imx6_soc_volt[num - 1]);
+        if (ret > 0)
+                transition_latency += ret * 1000;
+        ret = regulator_set_voltage_time(pu_reg, imx6_soc_volt[0], imx6_soc_volt[num - 1]);
+        if (ret > 0)
+                transition_latency += ret * 1000;
+
+        /*
          * OPP is maintained in order of increasing frequency, and
          * freq_table initialised from OPP is therefore sorted in the
          * same order.
@@ -221,18 +281,6 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
         if (ret > 0)
                 transition_latency += ret * 1000;
 
-        /* Count vddpu and vddsoc latency in for 1.2 GHz support */
-        if (freq_table[num].frequency == FREQ_1P2_GHZ / 1000) {
-                ret = regulator_set_voltage_time(pu_reg, PU_SOC_VOLTAGE_NORMAL,
-                                                 PU_SOC_VOLTAGE_HIGH);
-                if (ret > 0)
-                        transition_latency += ret * 1000;
-                ret = regulator_set_voltage_time(soc_reg, PU_SOC_VOLTAGE_NORMAL,
-                                                 PU_SOC_VOLTAGE_HIGH);
-                if (ret > 0)
-                        transition_latency += ret * 1000;
-        }
-
         ret = cpufreq_register_driver(&imx6q_cpufreq_driver);
         if (ret) {
                 dev_err(cpu_dev, "failed register driver: %d\n", ret);