1 /* 2 * Copyright (C) 2011 Dmitry Eremin-Solenikov 3 * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org> 4 * and Markus Demleitner <msdemlei@cl.uni-heidelberg.de> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs, 11 * that is iMac G5 and latest single CPU desktop. 12 */ 13 14 #undef DEBUG 15 16 #include <linux/module.h> 17 #include <linux/types.h> 18 #include <linux/errno.h> 19 #include <linux/kernel.h> 20 #include <linux/delay.h> 21 #include <linux/sched.h> 22 #include <linux/cpufreq.h> 23 #include <linux/init.h> 24 #include <linux/completion.h> 25 #include <linux/mutex.h> 26 #include <linux/time.h> 27 #include <linux/of_device.h> 28 29 #define DBG(fmt...) pr_debug(fmt) 30 31 /* see 970FX user manual */ 32 33 #define SCOM_PCR 0x0aa001 /* PCR scom addr */ 34 35 #define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */ 36 #define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */ 37 #define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */ 38 #define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */ 39 #define PCR_SPEED_MASK 0x000e0000U /* speed mask */ 40 #define PCR_SPEED_SHIFT 17 41 #define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */ 42 #define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */ 43 #define PCR_TARGET_TIME_MASK 0x00006000U /* target time */ 44 #define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */ 45 #define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */ 46 #define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */ 47 48 #define SCOM_PSR 0x408001 /* PSR scom addr */ 49 /* warning: PSR is a 64 bits register */ 50 #define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */ 51 #define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */ 52 #define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */ 53 #define PSR_CUR_SPEED_SHIFT (56) 54 55 /* 56 * The G5 only supports two frequencies (Quarter speed is not supported) 57 */ 58 #define CPUFREQ_HIGH 0 59 #define CPUFREQ_LOW 1 60 61 static struct cpufreq_frequency_table maple_cpu_freqs[] = { 62 {CPUFREQ_HIGH, 0}, 63 {CPUFREQ_LOW, 0}, 64 {0, CPUFREQ_TABLE_END}, 65 }; 66 67 static struct freq_attr *maple_cpu_freqs_attr[] = { 68 &cpufreq_freq_attr_scaling_available_freqs, 69 NULL, 70 }; 71 72 /* Power mode data is an array of the 32 bits PCR values to use for 73 * the various frequencies, retrieved from the device-tree 74 */ 75 static int maple_pmode_cur; 76 77 static DEFINE_MUTEX(maple_switch_mutex); 78 79 static const u32 *maple_pmode_data; 80 static int maple_pmode_max; 81 82 /* 83 * SCOM based frequency switching for 970FX rev3 84 */ 85 static int maple_scom_switch_freq(int speed_mode) 86 { 87 unsigned long flags; 88 int to; 89 90 local_irq_save(flags); 91 92 /* Clear PCR high */ 93 scom970_write(SCOM_PCR, 0); 94 /* Clear PCR low */ 95 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0); 96 /* Set PCR low */ 97 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 98 maple_pmode_data[speed_mode]); 99 100 /* Wait for completion */ 101 for (to = 0; to < 10; to++) { 102 unsigned long psr = scom970_read(SCOM_PSR); 103 104 if ((psr & PSR_CMD_RECEIVED) == 0 && 105 (((psr >> PSR_CUR_SPEED_SHIFT) ^ 106 (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3) 107 == 0) 108 break; 109 if (psr & PSR_CMD_COMPLETED) 110 break; 111 udelay(100); 112 } 113 114 local_irq_restore(flags); 115 116 maple_pmode_cur = speed_mode; 117 ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul; 118 119 return 0; 120 } 121 122 static int maple_scom_query_freq(void) 123 { 124 unsigned long psr = scom970_read(SCOM_PSR); 125 int i; 126 127 for (i = 0; i <= maple_pmode_max; i++) 128 if ((((psr >> PSR_CUR_SPEED_SHIFT) ^ 129 (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0) 130 break; 131 return i; 132 } 133 134 /* 135 * Common interface to the cpufreq core 136 */ 137 138 static int maple_cpufreq_verify(struct cpufreq_policy *policy) 139 { 140 return cpufreq_frequency_table_verify(policy, maple_cpu_freqs); 141 } 142 143 static int maple_cpufreq_target(struct cpufreq_policy *policy, 144 unsigned int target_freq, unsigned int relation) 145 { 146 unsigned int newstate = 0; 147 struct cpufreq_freqs freqs; 148 int rc; 149 150 if (cpufreq_frequency_table_target(policy, maple_cpu_freqs, 151 target_freq, relation, &newstate)) 152 return -EINVAL; 153 154 if (maple_pmode_cur == newstate) 155 return 0; 156 157 mutex_lock(&maple_switch_mutex); 158 159 freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency; 160 freqs.new = maple_cpu_freqs[newstate].frequency; 161 162 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); 163 rc = maple_scom_switch_freq(newstate); 164 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); 165 166 mutex_unlock(&maple_switch_mutex); 167 168 return rc; 169 } 170 171 static unsigned int maple_cpufreq_get_speed(unsigned int cpu) 172 { 173 return maple_cpu_freqs[maple_pmode_cur].frequency; 174 } 175 176 static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) 177 { 178 policy->cpuinfo.transition_latency = 12000; 179 policy->cur = maple_cpu_freqs[maple_scom_query_freq()].frequency; 180 /* secondary CPUs are tied to the primary one by the 181 * cpufreq core if in the secondary policy we tell it that 182 * it actually must be one policy together with all others. */ 183 cpumask_setall(policy->cpus); 184 cpufreq_frequency_table_get_attr(maple_cpu_freqs, policy->cpu); 185 186 return cpufreq_frequency_table_cpuinfo(policy, 187 maple_cpu_freqs); 188 } 189 190 191 static struct cpufreq_driver maple_cpufreq_driver = { 192 .name = "maple", 193 .flags = CPUFREQ_CONST_LOOPS, 194 .init = maple_cpufreq_cpu_init, 195 .verify = maple_cpufreq_verify, 196 .target = maple_cpufreq_target, 197 .get = maple_cpufreq_get_speed, 198 .attr = maple_cpu_freqs_attr, 199 }; 200 201 static int __init maple_cpufreq_init(void) 202 { 203 struct device_node *cpunode; 204 unsigned int psize; 205 unsigned long max_freq; 206 const u32 *valp; 207 u32 pvr_hi; 208 int rc = -ENODEV; 209 210 /* 211 * Behave here like powermac driver which checks machine compatibility 212 * to ease merging of two drivers in future. 213 */ 214 if (!of_machine_is_compatible("Momentum,Maple") && 215 !of_machine_is_compatible("Momentum,Apache")) 216 return 0; 217 218 /* Get first CPU node */ 219 cpunode = of_cpu_device_node_get(0); 220 if (cpunode == NULL) { 221 printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n"); 222 goto bail_noprops; 223 } 224 225 /* Check 970FX for now */ 226 /* we actually don't care on which CPU to access PVR */ 227 pvr_hi = PVR_VER(mfspr(SPRN_PVR)); 228 if (pvr_hi != 0x3c && pvr_hi != 0x44) { 229 printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n", 230 pvr_hi); 231 goto bail_noprops; 232 } 233 234 /* Look for the powertune data in the device-tree */ 235 /* 236 * On Maple this property is provided by PIBS in dual-processor config, 237 * not provided by PIBS in CPU0 config and also not provided by SLOF, 238 * so YMMV 239 */ 240 maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); 241 if (!maple_pmode_data) { 242 DBG("No power-mode-data !\n"); 243 goto bail_noprops; 244 } 245 maple_pmode_max = psize / sizeof(u32) - 1; 246 247 /* 248 * From what I see, clock-frequency is always the maximal frequency. 249 * The current driver can not slew sysclk yet, so we really only deal 250 * with powertune steps for now. We also only implement full freq and 251 * half freq in this version. So far, I haven't yet seen a machine 252 * supporting anything else. 253 */ 254 valp = of_get_property(cpunode, "clock-frequency", NULL); 255 if (!valp) 256 return -ENODEV; 257 max_freq = (*valp)/1000; 258 maple_cpu_freqs[0].frequency = max_freq; 259 maple_cpu_freqs[1].frequency = max_freq/2; 260 261 /* Force apply current frequency to make sure everything is in 262 * sync (voltage is right for example). Firmware may leave us with 263 * a strange setting ... 264 */ 265 msleep(10); 266 maple_pmode_cur = -1; 267 maple_scom_switch_freq(maple_scom_query_freq()); 268 269 printk(KERN_INFO "Registering Maple CPU frequency driver\n"); 270 printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", 271 maple_cpu_freqs[1].frequency/1000, 272 maple_cpu_freqs[0].frequency/1000, 273 maple_cpu_freqs[maple_pmode_cur].frequency/1000); 274 275 rc = cpufreq_register_driver(&maple_cpufreq_driver); 276 277 of_node_put(cpunode); 278 279 return rc; 280 281 bail_noprops: 282 of_node_put(cpunode); 283 284 return rc; 285 } 286 287 module_init(maple_cpufreq_init); 288 289 290 MODULE_LICENSE("GPL"); 291