1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2010 Google, Inc. 4 * 5 * Author: 6 * Colin Cross <ccross@google.com> 7 * Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation 8 */ 9 10 #include <linux/clk.h> 11 #include <linux/cpufreq.h> 12 #include <linux/err.h> 13 #include <linux/init.h> 14 #include <linux/module.h> 15 #include <linux/platform_device.h> 16 #include <linux/types.h> 17 18 static struct cpufreq_frequency_table freq_table[] = { 19 { .frequency = 216000 }, 20 { .frequency = 312000 }, 21 { .frequency = 456000 }, 22 { .frequency = 608000 }, 23 { .frequency = 760000 }, 24 { .frequency = 816000 }, 25 { .frequency = 912000 }, 26 { .frequency = 1000000 }, 27 { .frequency = CPUFREQ_TABLE_END }, 28 }; 29 30 struct tegra20_cpufreq { 31 struct device *dev; 32 struct cpufreq_driver driver; 33 struct clk *cpu_clk; 34 struct clk *pll_x_clk; 35 struct clk *pll_p_clk; 36 bool pll_x_prepared; 37 }; 38 39 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy, 40 unsigned int index) 41 { 42 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data(); 43 unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000; 44 45 /* 46 * Don't switch to intermediate freq if: 47 * - we are already at it, i.e. policy->cur == ifreq 48 * - index corresponds to ifreq 49 */ 50 if (freq_table[index].frequency == ifreq || policy->cur == ifreq) 51 return 0; 52 53 return ifreq; 54 } 55 56 static int tegra_target_intermediate(struct cpufreq_policy *policy, 57 unsigned int index) 58 { 59 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data(); 60 int ret; 61 62 /* 63 * Take an extra reference to the main pll so it doesn't turn 64 * off when we move the cpu off of it as enabling it again while we 65 * switch to it from tegra_target() would take additional time. 66 * 67 * When target-freq is equal to intermediate freq we don't need to 68 * switch to an intermediate freq and so this routine isn't called. 69 * Also, we wouldn't be using pll_x anymore and must not take extra 70 * reference to it, as it can be disabled now to save some power. 71 */ 72 clk_prepare_enable(cpufreq->pll_x_clk); 73 74 ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk); 75 if (ret) 76 clk_disable_unprepare(cpufreq->pll_x_clk); 77 else 78 cpufreq->pll_x_prepared = true; 79 80 return ret; 81 } 82 83 static int tegra_target(struct cpufreq_policy *policy, unsigned int index) 84 { 85 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data(); 86 unsigned long rate = freq_table[index].frequency; 87 unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000; 88 int ret; 89 90 /* 91 * target freq == pll_p, don't need to take extra reference to pll_x_clk 92 * as it isn't used anymore. 93 */ 94 if (rate == ifreq) 95 return clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk); 96 97 ret = clk_set_rate(cpufreq->pll_x_clk, rate * 1000); 98 /* Restore to earlier frequency on error, i.e. pll_x */ 99 if (ret) 100 dev_err(cpufreq->dev, "Failed to change pll_x to %lu\n", rate); 101 102 ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_x_clk); 103 /* This shouldn't fail while changing or restoring */ 104 WARN_ON(ret); 105 106 /* 107 * Drop count to pll_x clock only if we switched to intermediate freq 108 * earlier while transitioning to a target frequency. 109 */ 110 if (cpufreq->pll_x_prepared) { 111 clk_disable_unprepare(cpufreq->pll_x_clk); 112 cpufreq->pll_x_prepared = false; 113 } 114 115 return ret; 116 } 117 118 static int tegra_cpu_init(struct cpufreq_policy *policy) 119 { 120 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data(); 121 122 clk_prepare_enable(cpufreq->cpu_clk); 123 124 /* FIXME: what's the actual transition time? */ 125 cpufreq_generic_init(policy, freq_table, 300 * 1000); 126 policy->clk = cpufreq->cpu_clk; 127 policy->suspend_freq = freq_table[0].frequency; 128 return 0; 129 } 130 131 static int tegra_cpu_exit(struct cpufreq_policy *policy) 132 { 133 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data(); 134 135 clk_disable_unprepare(cpufreq->cpu_clk); 136 return 0; 137 } 138 139 static int tegra20_cpufreq_probe(struct platform_device *pdev) 140 { 141 struct tegra20_cpufreq *cpufreq; 142 int err; 143 144 cpufreq = devm_kzalloc(&pdev->dev, sizeof(*cpufreq), GFP_KERNEL); 145 if (!cpufreq) 146 return -ENOMEM; 147 148 cpufreq->cpu_clk = clk_get_sys(NULL, "cclk"); 149 if (IS_ERR(cpufreq->cpu_clk)) 150 return PTR_ERR(cpufreq->cpu_clk); 151 152 cpufreq->pll_x_clk = clk_get_sys(NULL, "pll_x"); 153 if (IS_ERR(cpufreq->pll_x_clk)) { 154 err = PTR_ERR(cpufreq->pll_x_clk); 155 goto put_cpu; 156 } 157 158 cpufreq->pll_p_clk = clk_get_sys(NULL, "pll_p"); 159 if (IS_ERR(cpufreq->pll_p_clk)) { 160 err = PTR_ERR(cpufreq->pll_p_clk); 161 goto put_pll_x; 162 } 163 164 cpufreq->dev = &pdev->dev; 165 cpufreq->driver.get = cpufreq_generic_get; 166 cpufreq->driver.attr = cpufreq_generic_attr; 167 cpufreq->driver.init = tegra_cpu_init; 168 cpufreq->driver.exit = tegra_cpu_exit; 169 cpufreq->driver.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK; 170 cpufreq->driver.verify = cpufreq_generic_frequency_table_verify; 171 cpufreq->driver.suspend = cpufreq_generic_suspend; 172 cpufreq->driver.driver_data = cpufreq; 173 cpufreq->driver.target_index = tegra_target; 174 cpufreq->driver.get_intermediate = tegra_get_intermediate; 175 cpufreq->driver.target_intermediate = tegra_target_intermediate; 176 snprintf(cpufreq->driver.name, CPUFREQ_NAME_LEN, "tegra"); 177 178 err = cpufreq_register_driver(&cpufreq->driver); 179 if (err) 180 goto put_pll_p; 181 182 platform_set_drvdata(pdev, cpufreq); 183 184 return 0; 185 186 put_pll_p: 187 clk_put(cpufreq->pll_p_clk); 188 put_pll_x: 189 clk_put(cpufreq->pll_x_clk); 190 put_cpu: 191 clk_put(cpufreq->cpu_clk); 192 193 return err; 194 } 195 196 static int tegra20_cpufreq_remove(struct platform_device *pdev) 197 { 198 struct tegra20_cpufreq *cpufreq = platform_get_drvdata(pdev); 199 200 cpufreq_unregister_driver(&cpufreq->driver); 201 202 clk_put(cpufreq->pll_p_clk); 203 clk_put(cpufreq->pll_x_clk); 204 clk_put(cpufreq->cpu_clk); 205 206 return 0; 207 } 208 209 static struct platform_driver tegra20_cpufreq_driver = { 210 .probe = tegra20_cpufreq_probe, 211 .remove = tegra20_cpufreq_remove, 212 .driver = { 213 .name = "tegra20-cpufreq", 214 }, 215 }; 216 module_platform_driver(tegra20_cpufreq_driver); 217 218 MODULE_ALIAS("platform:tegra20-cpufreq"); 219 MODULE_AUTHOR("Colin Cross <ccross@android.com>"); 220 MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver"); 221 MODULE_LICENSE("GPL"); 222