1 /* 2 * drivers/cpufreq/spear-cpufreq.c 3 * 4 * CPU Frequency Scaling for SPEAr platform 5 * 6 * Copyright (C) 2012 ST Microelectronics 7 * Deepak Sikri <deepak.sikri@st.com> 8 * 9 * This file is licensed under the terms of the GNU General Public 10 * License version 2. This program is licensed "as is" without any 11 * warranty of any kind, whether express or implied. 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/clk.h> 17 #include <linux/cpufreq.h> 18 #include <linux/err.h> 19 #include <linux/init.h> 20 #include <linux/module.h> 21 #include <linux/of.h> 22 #include <linux/slab.h> 23 #include <linux/types.h> 24 25 /* SPEAr CPUFreq driver data structure */ 26 static struct { 27 struct clk *clk; 28 unsigned int transition_latency; 29 struct cpufreq_frequency_table *freq_tbl; 30 u32 cnt; 31 } spear_cpufreq; 32 33 int spear_cpufreq_verify(struct cpufreq_policy *policy) 34 { 35 return cpufreq_frequency_table_verify(policy, spear_cpufreq.freq_tbl); 36 } 37 38 static unsigned int spear_cpufreq_get(unsigned int cpu) 39 { 40 return clk_get_rate(spear_cpufreq.clk) / 1000; 41 } 42 43 static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq) 44 { 45 struct clk *sys_pclk; 46 int pclk; 47 /* 48 * In SPEAr1340, cpu clk's parent sys clk can take input from 49 * following sources 50 */ 51 const char *sys_clk_src[] = { 52 "sys_syn_clk", 53 "pll1_clk", 54 "pll2_clk", 55 "pll3_clk", 56 }; 57 58 /* 59 * As sys clk can have multiple source with their own range 60 * limitation so we choose possible sources accordingly 61 */ 62 if (newfreq <= 300000000) 63 pclk = 0; /* src is sys_syn_clk */ 64 else if (newfreq > 300000000 && newfreq <= 500000000) 65 pclk = 3; /* src is pll3_clk */ 66 else if (newfreq == 600000000) 67 pclk = 1; /* src is pll1_clk */ 68 else 69 return ERR_PTR(-EINVAL); 70 71 /* Get parent to sys clock */ 72 sys_pclk = clk_get(NULL, sys_clk_src[pclk]); 73 if (IS_ERR(sys_pclk)) 74 pr_err("Failed to get %s clock\n", sys_clk_src[pclk]); 75 76 return sys_pclk; 77 } 78 79 /* 80 * In SPEAr1340, we cannot use newfreq directly because we need to actually 81 * access a source clock (clk) which might not be ancestor of cpu at present. 82 * Hence in SPEAr1340 we would operate on source clock directly before switching 83 * cpu clock to it. 84 */ 85 static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq) 86 { 87 struct clk *sys_clk; 88 int ret = 0; 89 90 sys_clk = clk_get_parent(spear_cpufreq.clk); 91 if (IS_ERR(sys_clk)) { 92 pr_err("failed to get cpu's parent (sys) clock\n"); 93 return PTR_ERR(sys_clk); 94 } 95 96 /* Set the rate of the source clock before changing the parent */ 97 ret = clk_set_rate(sys_pclk, newfreq); 98 if (ret) { 99 pr_err("Failed to set sys clk rate to %lu\n", newfreq); 100 return ret; 101 } 102 103 ret = clk_set_parent(sys_clk, sys_pclk); 104 if (ret) { 105 pr_err("Failed to set sys clk parent\n"); 106 return ret; 107 } 108 109 return 0; 110 } 111 112 static int spear_cpufreq_target(struct cpufreq_policy *policy, 113 unsigned int target_freq, unsigned int relation) 114 { 115 struct cpufreq_freqs freqs; 116 unsigned long newfreq; 117 struct clk *srcclk; 118 int index, ret, mult = 1; 119 120 if (cpufreq_frequency_table_target(policy, spear_cpufreq.freq_tbl, 121 target_freq, relation, &index)) 122 return -EINVAL; 123 124 freqs.cpu = policy->cpu; 125 freqs.old = spear_cpufreq_get(0); 126 127 newfreq = spear_cpufreq.freq_tbl[index].frequency * 1000; 128 if (of_machine_is_compatible("st,spear1340")) { 129 /* 130 * SPEAr1340 is special in the sense that due to the possibility 131 * of multiple clock sources for cpu clk's parent we can have 132 * different clock source for different frequency of cpu clk. 133 * Hence we need to choose one from amongst these possible clock 134 * sources. 135 */ 136 srcclk = spear1340_cpu_get_possible_parent(newfreq); 137 if (IS_ERR(srcclk)) { 138 pr_err("Failed to get src clk\n"); 139 return PTR_ERR(srcclk); 140 } 141 142 /* SPEAr1340: src clk is always 2 * intended cpu clk */ 143 mult = 2; 144 } else { 145 /* 146 * src clock to be altered is ancestor of cpu clock. Hence we 147 * can directly work on cpu clk 148 */ 149 srcclk = spear_cpufreq.clk; 150 } 151 152 newfreq = clk_round_rate(srcclk, newfreq * mult); 153 if (newfreq < 0) { 154 pr_err("clk_round_rate failed for cpu src clock\n"); 155 return newfreq; 156 } 157 158 freqs.new = newfreq / 1000; 159 freqs.new /= mult; 160 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 161 162 if (mult == 2) 163 ret = spear1340_set_cpu_rate(srcclk, newfreq); 164 else 165 ret = clk_set_rate(spear_cpufreq.clk, newfreq); 166 167 /* Get current rate after clk_set_rate, in case of failure */ 168 if (ret) { 169 pr_err("CPU Freq: cpu clk_set_rate failed: %d\n", ret); 170 freqs.new = clk_get_rate(spear_cpufreq.clk) / 1000; 171 } 172 173 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 174 return ret; 175 } 176 177 static int spear_cpufreq_init(struct cpufreq_policy *policy) 178 { 179 int ret; 180 181 ret = cpufreq_frequency_table_cpuinfo(policy, spear_cpufreq.freq_tbl); 182 if (ret) { 183 pr_err("cpufreq_frequency_table_cpuinfo() failed"); 184 return ret; 185 } 186 187 cpufreq_frequency_table_get_attr(spear_cpufreq.freq_tbl, policy->cpu); 188 policy->cpuinfo.transition_latency = spear_cpufreq.transition_latency; 189 policy->cur = spear_cpufreq_get(0); 190 191 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu)); 192 cpumask_copy(policy->related_cpus, policy->cpus); 193 194 return 0; 195 } 196 197 static int spear_cpufreq_exit(struct cpufreq_policy *policy) 198 { 199 cpufreq_frequency_table_put_attr(policy->cpu); 200 return 0; 201 } 202 203 static struct freq_attr *spear_cpufreq_attr[] = { 204 &cpufreq_freq_attr_scaling_available_freqs, 205 NULL, 206 }; 207 208 static struct cpufreq_driver spear_cpufreq_driver = { 209 .name = "cpufreq-spear", 210 .flags = CPUFREQ_STICKY, 211 .verify = spear_cpufreq_verify, 212 .target = spear_cpufreq_target, 213 .get = spear_cpufreq_get, 214 .init = spear_cpufreq_init, 215 .exit = spear_cpufreq_exit, 216 .attr = spear_cpufreq_attr, 217 }; 218 219 static int spear_cpufreq_driver_init(void) 220 { 221 struct device_node *np; 222 const struct property *prop; 223 struct cpufreq_frequency_table *freq_tbl; 224 const __be32 *val; 225 int cnt, i, ret; 226 227 np = of_find_node_by_path("/cpus/cpu@0"); 228 if (!np) { 229 pr_err("No cpu node found"); 230 return -ENODEV; 231 } 232 233 if (of_property_read_u32(np, "clock-latency", 234 &spear_cpufreq.transition_latency)) 235 spear_cpufreq.transition_latency = CPUFREQ_ETERNAL; 236 237 prop = of_find_property(np, "cpufreq_tbl", NULL); 238 if (!prop || !prop->value) { 239 pr_err("Invalid cpufreq_tbl"); 240 ret = -ENODEV; 241 goto out_put_node; 242 } 243 244 cnt = prop->length / sizeof(u32); 245 val = prop->value; 246 247 freq_tbl = kmalloc(sizeof(*freq_tbl) * (cnt + 1), GFP_KERNEL); 248 if (!freq_tbl) { 249 ret = -ENOMEM; 250 goto out_put_node; 251 } 252 253 for (i = 0; i < cnt; i++) { 254 freq_tbl[i].index = i; 255 freq_tbl[i].frequency = be32_to_cpup(val++); 256 } 257 258 freq_tbl[i].index = i; 259 freq_tbl[i].frequency = CPUFREQ_TABLE_END; 260 261 spear_cpufreq.freq_tbl = freq_tbl; 262 263 of_node_put(np); 264 265 spear_cpufreq.clk = clk_get(NULL, "cpu_clk"); 266 if (IS_ERR(spear_cpufreq.clk)) { 267 pr_err("Unable to get CPU clock\n"); 268 ret = PTR_ERR(spear_cpufreq.clk); 269 goto out_put_mem; 270 } 271 272 ret = cpufreq_register_driver(&spear_cpufreq_driver); 273 if (!ret) 274 return 0; 275 276 pr_err("failed register driver: %d\n", ret); 277 clk_put(spear_cpufreq.clk); 278 279 out_put_mem: 280 kfree(freq_tbl); 281 return ret; 282 283 out_put_node: 284 of_node_put(np); 285 return ret; 286 } 287 late_initcall(spear_cpufreq_driver_init); 288 289 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>"); 290 MODULE_DESCRIPTION("SPEAr CPUFreq driver"); 291 MODULE_LICENSE("GPL"); 292