drivers/cpufreq/imx6q-cpufreq.c

   1 /*
   2  * Copyright (C) 2013 Freescale Semiconductor, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/cpufreq.h>
  11 #include <linux/delay.h>
  12 #include <linux/err.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/opp.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/regulator/consumer.h>
  18
  19 #define PU_SOC_VOLTAGE_NORMAL   1250000
  20 #define PU_SOC_VOLTAGE_HIGH     1275000
  21 #define FREQ_1P2_GHZ            1200000000
  22
  23 static struct regulator *arm_reg;
  24 static struct regulator *pu_reg;
  25 static struct regulator *soc_reg;
  26
  27 static struct clk *arm_clk;
  28 static struct clk *pll1_sys_clk;
  29 static struct clk *pll1_sw_clk;
  30 static struct clk *step_clk;
  31 static struct clk *pll2_pfd2_396m_clk;
  32
  33 static struct device *cpu_dev;
  34 static struct cpufreq_frequency_table *freq_table;
  35 static unsigned int transition_latency;
  36
  37 static int imx6q_verify_speed(struct cpufreq_policy *policy)
  38 {
  39         return cpufreq_frequency_table_verify(policy, freq_table);
  40 }
  41
  42 static unsigned int imx6q_get_speed(unsigned int cpu)
  43 {
  44         return clk_get_rate(arm_clk) / 1000;
  45 }
  46
  47 static int imx6q_set_target(struct cpufreq_policy *policy,
  48                             unsigned int target_freq, unsigned int relation)
  49 {
  50         struct cpufreq_freqs freqs;
  51         struct opp *opp;
  52         unsigned long freq_hz, volt, volt_old;
  53         unsigned int index;
  54         int ret;
  55
  56         ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
  57                                              relation, &index);
  58         if (ret) {
  59                 dev_err(cpu_dev, "failed to match target frequency %d: %d\n",
  60                         target_freq, ret);
  61                 return ret;
  62         }
  63
  64         freqs.new = freq_table[index].frequency;
  65         freq_hz = freqs.new * 1000;
  66         freqs.old = clk_get_rate(arm_clk) / 1000;
  67
  68         if (freqs.old == freqs.new)
  69                 return 0;
  70
  71         rcu_read_lock();
  72         opp = opp_find_freq_ceil(cpu_dev, &freq_hz);
  73         if (IS_ERR(opp)) {
  74                 rcu_read_unlock();
  75                 dev_err(cpu_dev, "failed to find OPP for %ld\n", freq_hz);
  76                 return PTR_ERR(opp);
  77         }
  78
  79         volt = opp_get_voltage(opp);
  80         rcu_read_unlock();
  81         volt_old = regulator_get_voltage(arm_reg);
  82
  83         dev_dbg(cpu_dev, "%u MHz, %ld mV --> %u MHz, %ld mV\n",
  84                 freqs.old / 1000, volt_old / 1000,
  85                 freqs.new / 1000, volt / 1000);
  86
  87         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  88
  89         /* scaling up?  scale voltage before frequency */
  90         if (freqs.new > freqs.old) {
  91                 ret = regulator_set_voltage_tol(arm_reg, volt, 0);
  92                 if (ret) {
  93                         dev_err(cpu_dev,
  94                                 "failed to scale vddarm up: %d\n", ret);
  95                         freqs.new = freqs.old;
  96                         goto post_notify;
  97                 }
  98
  99                 /*
 100                  * Need to increase vddpu and vddsoc for safety
 101                  * if we are about to run at 1.2 GHz.
 102                  */
 103                 if (freqs.new == FREQ_1P2_GHZ / 1000) {
 104                         regulator_set_voltage_tol(pu_reg,
 105                                         PU_SOC_VOLTAGE_HIGH, 0);
 106                         regulator_set_voltage_tol(soc_reg,
 107                                         PU_SOC_VOLTAGE_HIGH, 0);
 108                 }
 109         }
 110
 111         /*
 112          * The setpoints are selected per PLL/PDF frequencies, so we need to
 113          * reprogram PLL for frequency scaling.  The procedure of reprogramming
 114          * PLL1 is as below.
 115          *
 116          *  - Enable pll2_pfd2_396m_clk and reparent pll1_sw_clk to it
 117          *  - Reprogram pll1_sys_clk and reparent pll1_sw_clk back to it
 118          *  - Disable pll2_pfd2_396m_clk
 119          */
 120         clk_prepare_enable(pll2_pfd2_396m_clk);
 121         clk_set_parent(step_clk, pll2_pfd2_396m_clk);
 122         clk_set_parent(pll1_sw_clk, step_clk);
 123         if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk)) {
 124                 clk_set_rate(pll1_sys_clk, freqs.new * 1000);
 125                 /*
 126                  * If we are leaving 396 MHz set-point, we need to enable
 127                  * pll1_sys_clk and disable pll2_pfd2_396m_clk to keep
 128                  * their use count correct.
 129                  */
 130                 if (freqs.old * 1000 <= clk_get_rate(pll2_pfd2_396m_clk)) {
 131                         clk_prepare_enable(pll1_sys_clk);
 132                         clk_disable_unprepare(pll2_pfd2_396m_clk);
 133                 }
 134                 clk_set_parent(pll1_sw_clk, pll1_sys_clk);
 135                 clk_disable_unprepare(pll2_pfd2_396m_clk);
 136         } else {
 137                 /*
 138                  * Disable pll1_sys_clk if pll2_pfd2_396m_clk is sufficient
 139                  * to provide the frequency.
 140                  */
 141                 clk_disable_unprepare(pll1_sys_clk);
 142         }
 143
 144         /* Ensure the arm clock divider is what we expect */
 145         ret = clk_set_rate(arm_clk, freqs.new * 1000);
 146         if (ret) {
 147                 dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
 148                 regulator_set_voltage_tol(arm_reg, volt_old, 0);
 149                 freqs.new = freqs.old;
 150                 goto post_notify;
 151         }
 152
 153         /* scaling down?  scale voltage after frequency */
 154         if (freqs.new < freqs.old) {
 155                 ret = regulator_set_voltage_tol(arm_reg, volt, 0);
 156                 if (ret) {
 157                         dev_warn(cpu_dev,
 158                                  "failed to scale vddarm down: %d\n", ret);
 159                         ret = 0;
 160                 }
 161
 162                 if (freqs.old == FREQ_1P2_GHZ / 1000) {
 163                         regulator_set_voltage_tol(pu_reg,
 164                                         PU_SOC_VOLTAGE_NORMAL, 0);
 165                         regulator_set_voltage_tol(soc_reg,
 166                                         PU_SOC_VOLTAGE_NORMAL, 0);
 167                 }
 168         }
 169
 170 post_notify:
 171         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 172
 173         return ret;
 174 }
 175
 176 static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
 177 {
 178         int ret;
 179
 180         ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 181         if (ret) {
 182                 dev_err(cpu_dev, "invalid frequency table: %d\n", ret);
 183                 return ret;
 184         }
 185
 186         policy->cpuinfo.transition_latency = transition_latency;
 187         policy->cur = clk_get_rate(arm_clk) / 1000;
 188         cpumask_setall(policy->cpus);
 189         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 190
 191         return 0;
 192 }
 193
 194 static int imx6q_cpufreq_exit(struct cpufreq_policy *policy)
 195 {
 196         cpufreq_frequency_table_put_attr(policy->cpu);
 197         return 0;
 198 }
 199
 200 static struct freq_attr *imx6q_cpufreq_attr[] = {
 201         &cpufreq_freq_attr_scaling_available_freqs,
 202         NULL,
 203 };
 204
 205 static struct cpufreq_driver imx6q_cpufreq_driver = {
 206         .verify = imx6q_verify_speed,
 207         .target = imx6q_set_target,
 208         .get = imx6q_get_speed,
 209         .init = imx6q_cpufreq_init,
 210         .exit = imx6q_cpufreq_exit,
 211         .name = "imx6q-cpufreq",
 212         .attr = imx6q_cpufreq_attr,
 213 };
 214
 215 static int imx6q_cpufreq_probe(struct platform_device *pdev)
 216 {
 217         struct device_node *np;
 218         struct opp *opp;
 219         unsigned long min_volt, max_volt;
 220         int num, ret;
 221
 222         cpu_dev = &pdev->dev;
 223
 224         np = of_find_node_by_path("/cpus/cpu@0");
 225         if (!np) {
 226                 dev_err(cpu_dev, "failed to find cpu0 node\n");
 227                 return -ENOENT;
 228         }
 229
 230         cpu_dev->of_node = np;
 231
 232         arm_clk = devm_clk_get(cpu_dev, "arm");
 233         pll1_sys_clk = devm_clk_get(cpu_dev, "pll1_sys");
 234         pll1_sw_clk = devm_clk_get(cpu_dev, "pll1_sw");
 235         step_clk = devm_clk_get(cpu_dev, "step");
 236         pll2_pfd2_396m_clk = devm_clk_get(cpu_dev, "pll2_pfd2_396m");
 237         if (IS_ERR(arm_clk) || IS_ERR(pll1_sys_clk) || IS_ERR(pll1_sw_clk) ||
 238             IS_ERR(step_clk) || IS_ERR(pll2_pfd2_396m_clk)) {
 239                 dev_err(cpu_dev, "failed to get clocks\n");
 240                 ret = -ENOENT;
 241                 goto put_node;
 242         }
 243
 244         arm_reg = devm_regulator_get(cpu_dev, "arm");
 245         pu_reg = devm_regulator_get(cpu_dev, "pu");
 246         soc_reg = devm_regulator_get(cpu_dev, "soc");
 247         if (IS_ERR(arm_reg) || IS_ERR(pu_reg) || IS_ERR(soc_reg)) {
 248                 dev_err(cpu_dev, "failed to get regulators\n");
 249                 ret = -ENOENT;
 250                 goto put_node;
 251         }
 252
 253         /* We expect an OPP table supplied by platform */
 254         num = opp_get_opp_count(cpu_dev);
 255         if (num < 0) {
 256                 ret = num;
 257                 dev_err(cpu_dev, "no OPP table is found: %d\n", ret);
 258                 goto put_node;
 259         }
 260
 261         ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
 262         if (ret) {
 263                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 264                 goto put_node;
 265         }
 266
 267         if (of_property_read_u32(np, "clock-latency", &transition_latency))
 268                 transition_latency = CPUFREQ_ETERNAL;
 269
 270         /*
 271          * OPP is maintained in order of increasing frequency, and
 272          * freq_table initialised from OPP is therefore sorted in the
 273          * same order.
 274          */
 275         rcu_read_lock();
 276         opp = opp_find_freq_exact(cpu_dev,
 277                                   freq_table[0].frequency * 1000, true);
 278         min_volt = opp_get_voltage(opp);
 279         opp = opp_find_freq_exact(cpu_dev,
 280                                   freq_table[--num].frequency * 1000, true);
 281         max_volt = opp_get_voltage(opp);
 282         rcu_read_unlock();
 283         ret = regulator_set_voltage_time(arm_reg, min_volt, max_volt);
 284         if (ret > 0)
 285                 transition_latency += ret * 1000;
 286
 287         /* Count vddpu and vddsoc latency in for 1.2 GHz support */
 288         if (freq_table[num].frequency == FREQ_1P2_GHZ / 1000) {
 289                 ret = regulator_set_voltage_time(pu_reg, PU_SOC_VOLTAGE_NORMAL,
 290                                                  PU_SOC_VOLTAGE_HIGH);
 291                 if (ret > 0)
 292                         transition_latency += ret * 1000;
 293                 ret = regulator_set_voltage_time(soc_reg, PU_SOC_VOLTAGE_NORMAL,
 294                                                  PU_SOC_VOLTAGE_HIGH);
 295                 if (ret > 0)
 296                         transition_latency += ret * 1000;
 297         }
 298
 299         ret = cpufreq_register_driver(&imx6q_cpufreq_driver);
 300         if (ret) {
 301                 dev_err(cpu_dev, "failed register driver: %d\n", ret);
 302                 goto free_freq_table;
 303         }
 304
 305         of_node_put(np);
 306         return 0;
 307
 308 free_freq_table:
 309         opp_free_cpufreq_table(cpu_dev, &freq_table);
 310 put_node:
 311         of_node_put(np);
 312         return ret;
 313 }
 314
 315 static int imx6q_cpufreq_remove(struct platform_device *pdev)
 316 {
 317         cpufreq_unregister_driver(&imx6q_cpufreq_driver);
 318         opp_free_cpufreq_table(cpu_dev, &freq_table);
 319
 320         return 0;
 321 }
 322
 323 static struct platform_driver imx6q_cpufreq_platdrv = {
 324         .driver = {
 325                 .name   = "imx6q-cpufreq",
 326                 .owner  = THIS_MODULE,
 327         },
 328         .probe          = imx6q_cpufreq_probe,
 329         .remove         = imx6q_cpufreq_remove,
 330 };
 331 module_platform_driver(imx6q_cpufreq_platdrv);
 332
 333 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 334 MODULE_DESCRIPTION("Freescale i.MX6Q cpufreq driver");
 335 MODULE_LICENSE("GPL");