drivers/cpufreq/maple-cpufreq.c

   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.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         freqs.cpu = 0;
 162
 163         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 164         rc = maple_scom_switch_freq(newstate);
 165         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 166
 167         mutex_unlock(&maple_switch_mutex);
 168
 169         return rc;
 170 }
 171
 172 static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
 173 {
 174         return maple_cpu_freqs[maple_pmode_cur].frequency;
 175 }
 176
 177 static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
 178 {
 179         policy->cpuinfo.transition_latency = 12000;
 180         policy->cur = maple_cpu_freqs[maple_scom_query_freq()].frequency;
 181         /* secondary CPUs are tied to the primary one by the
 182          * cpufreq core if in the secondary policy we tell it that
 183          * it actually must be one policy together with all others. */
 184         cpumask_setall(policy->cpus);
 185         cpufreq_frequency_table_get_attr(maple_cpu_freqs, policy->cpu);
 186
 187         return cpufreq_frequency_table_cpuinfo(policy,
 188                 maple_cpu_freqs);
 189 }
 190
 191
 192 static struct cpufreq_driver maple_cpufreq_driver = {
 193         .name           = "maple",
 194         .owner          = THIS_MODULE,
 195         .flags          = CPUFREQ_CONST_LOOPS,
 196         .init           = maple_cpufreq_cpu_init,
 197         .verify         = maple_cpufreq_verify,
 198         .target         = maple_cpufreq_target,
 199         .get            = maple_cpufreq_get_speed,
 200         .attr           = maple_cpu_freqs_attr,
 201 };
 202
 203 static int __init maple_cpufreq_init(void)
 204 {
 205         struct device_node *cpus;
 206         struct device_node *cpunode;
 207         unsigned int psize;
 208         unsigned long max_freq;
 209         const u32 *valp;
 210         u32 pvr_hi;
 211         int rc = -ENODEV;
 212
 213         /*
 214          * Behave here like powermac driver which checks machine compatibility
 215          * to ease merging of two drivers in future.
 216          */
 217         if (!of_machine_is_compatible("Momentum,Maple") &&
 218             !of_machine_is_compatible("Momentum,Apache"))
 219                 return 0;
 220
 221         cpus = of_find_node_by_path("/cpus");
 222         if (cpus == NULL) {
 223                 DBG("No /cpus node !\n");
 224                 return -ENODEV;
 225         }
 226
 227         /* Get first CPU node */
 228         for (cpunode = NULL;
 229              (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) {
 230                 const u32 *reg = of_get_property(cpunode, "reg", NULL);
 231                 if (reg == NULL || (*reg) != 0)
 232                         continue;
 233                 if (!strcmp(cpunode->type, "cpu"))
 234                         break;
 235         }
 236         if (cpunode == NULL) {
 237                 printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
 238                 goto bail_cpus;
 239         }
 240
 241         /* Check 970FX for now */
 242         /* we actually don't care on which CPU to access PVR */
 243         pvr_hi = PVR_VER(mfspr(SPRN_PVR));
 244         if (pvr_hi != 0x3c && pvr_hi != 0x44) {
 245                 printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n",
 246                                 pvr_hi);
 247                 goto bail_noprops;
 248         }
 249
 250         /* Look for the powertune data in the device-tree */
 251         /*
 252          * On Maple this property is provided by PIBS in dual-processor config,
 253          * not provided by PIBS in CPU0 config and also not provided by SLOF,
 254          * so YMMV
 255          */
 256         maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
 257         if (!maple_pmode_data) {
 258                 DBG("No power-mode-data !\n");
 259                 goto bail_noprops;
 260         }
 261         maple_pmode_max = psize / sizeof(u32) - 1;
 262
 263         /*
 264          * From what I see, clock-frequency is always the maximal frequency.
 265          * The current driver can not slew sysclk yet, so we really only deal
 266          * with powertune steps for now. We also only implement full freq and
 267          * half freq in this version. So far, I haven't yet seen a machine
 268          * supporting anything else.
 269          */
 270         valp = of_get_property(cpunode, "clock-frequency", NULL);
 271         if (!valp)
 272                 return -ENODEV;
 273         max_freq = (*valp)/1000;
 274         maple_cpu_freqs[0].frequency = max_freq;
 275         maple_cpu_freqs[1].frequency = max_freq/2;
 276
 277         /* Force apply current frequency to make sure everything is in
 278          * sync (voltage is right for example). Firmware may leave us with
 279          * a strange setting ...
 280          */
 281         msleep(10);
 282         maple_pmode_cur = -1;
 283         maple_scom_switch_freq(maple_scom_query_freq());
 284
 285         printk(KERN_INFO "Registering Maple CPU frequency driver\n");
 286         printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
 287                 maple_cpu_freqs[1].frequency/1000,
 288                 maple_cpu_freqs[0].frequency/1000,
 289                 maple_cpu_freqs[maple_pmode_cur].frequency/1000);
 290
 291         rc = cpufreq_register_driver(&maple_cpufreq_driver);
 292
 293         of_node_put(cpunode);
 294         of_node_put(cpus);
 295
 296         return rc;
 297
 298 bail_noprops:
 299         of_node_put(cpunode);
 300 bail_cpus:
 301         of_node_put(cpus);
 302
 303         return rc;
 304 }
 305
 306 module_init(maple_cpufreq_init);
 307
 308
 309 MODULE_LICENSE("GPL");