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_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 /* Power mode data is an array of the 32 bits PCR values to use for
  68  * the various frequencies, retrieved from the device-tree
  69  */
  70 static int maple_pmode_cur;
  71
  72 static DEFINE_MUTEX(maple_switch_mutex);
  73
  74 static const u32 *maple_pmode_data;
  75 static int maple_pmode_max;
  76
  77 /*
  78  * SCOM based frequency switching for 970FX rev3
  79  */
  80 static int maple_scom_switch_freq(int speed_mode)
  81 {
  82         unsigned long flags;
  83         int to;
  84
  85         local_irq_save(flags);
  86
  87         /* Clear PCR high */
  88         scom970_write(SCOM_PCR, 0);
  89         /* Clear PCR low */
  90         scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
  91         /* Set PCR low */
  92         scom970_write(SCOM_PCR, PCR_HILO_SELECT |
  93                       maple_pmode_data[speed_mode]);
  94
  95         /* Wait for completion */
  96         for (to = 0; to < 10; to++) {
  97                 unsigned long psr = scom970_read(SCOM_PSR);
  98
  99                 if ((psr & PSR_CMD_RECEIVED) == 0 &&
 100                     (((psr >> PSR_CUR_SPEED_SHIFT) ^
 101                       (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
 102                     == 0)
 103                         break;
 104                 if (psr & PSR_CMD_COMPLETED)
 105                         break;
 106                 udelay(100);
 107         }
 108
 109         local_irq_restore(flags);
 110
 111         maple_pmode_cur = speed_mode;
 112         ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul;
 113
 114         return 0;
 115 }
 116
 117 static int maple_scom_query_freq(void)
 118 {
 119         unsigned long psr = scom970_read(SCOM_PSR);
 120         int i;
 121
 122         for (i = 0; i <= maple_pmode_max; i++)
 123                 if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
 124                       (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
 125                         break;
 126         return i;
 127 }
 128
 129 /*
 130  * Common interface to the cpufreq core
 131  */
 132
 133 static int maple_cpufreq_target(struct cpufreq_policy *policy,
 134         unsigned int index)
 135 {
 136         struct cpufreq_freqs freqs;
 137         int rc;
 138
 139         mutex_lock(&maple_switch_mutex);
 140
 141         freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency;
 142         freqs.new = maple_cpu_freqs[index].frequency;
 143
 144         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 145         rc = maple_scom_switch_freq(index);
 146         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 147
 148         mutex_unlock(&maple_switch_mutex);
 149
 150         return rc;
 151 }
 152
 153 static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
 154 {
 155         return maple_cpu_freqs[maple_pmode_cur].frequency;
 156 }
 157
 158 static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
 159 {
 160         return cpufreq_generic_init(policy, maple_cpu_freqs, 12000);
 161 }
 162
 163 static struct cpufreq_driver maple_cpufreq_driver = {
 164         .name           = "maple",
 165         .flags          = CPUFREQ_CONST_LOOPS,
 166         .init           = maple_cpufreq_cpu_init,
 167         .verify         = cpufreq_generic_frequency_table_verify,
 168         .target_index   = maple_cpufreq_target,
 169         .get            = maple_cpufreq_get_speed,
 170         .attr           = cpufreq_generic_attr,
 171 };
 172
 173 static int __init maple_cpufreq_init(void)
 174 {
 175         struct device_node *cpunode;
 176         unsigned int psize;
 177         unsigned long max_freq;
 178         const u32 *valp;
 179         u32 pvr_hi;
 180         int rc = -ENODEV;
 181
 182         /*
 183          * Behave here like powermac driver which checks machine compatibility
 184          * to ease merging of two drivers in future.
 185          */
 186         if (!of_machine_is_compatible("Momentum,Maple") &&
 187             !of_machine_is_compatible("Momentum,Apache"))
 188                 return 0;
 189
 190         /* Get first CPU node */
 191         cpunode = of_cpu_device_node_get(0);
 192         if (cpunode == NULL) {
 193                 printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
 194                 goto bail_noprops;
 195         }
 196
 197         /* Check 970FX for now */
 198         /* we actually don't care on which CPU to access PVR */
 199         pvr_hi = PVR_VER(mfspr(SPRN_PVR));
 200         if (pvr_hi != 0x3c && pvr_hi != 0x44) {
 201                 printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n",
 202                                 pvr_hi);
 203                 goto bail_noprops;
 204         }
 205
 206         /* Look for the powertune data in the device-tree */
 207         /*
 208          * On Maple this property is provided by PIBS in dual-processor config,
 209          * not provided by PIBS in CPU0 config and also not provided by SLOF,
 210          * so YMMV
 211          */
 212         maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
 213         if (!maple_pmode_data) {
 214                 DBG("No power-mode-data !\n");
 215                 goto bail_noprops;
 216         }
 217         maple_pmode_max = psize / sizeof(u32) - 1;
 218
 219         /*
 220          * From what I see, clock-frequency is always the maximal frequency.
 221          * The current driver can not slew sysclk yet, so we really only deal
 222          * with powertune steps for now. We also only implement full freq and
 223          * half freq in this version. So far, I haven't yet seen a machine
 224          * supporting anything else.
 225          */
 226         valp = of_get_property(cpunode, "clock-frequency", NULL);
 227         if (!valp)
 228                 return -ENODEV;
 229         max_freq = (*valp)/1000;
 230         maple_cpu_freqs[0].frequency = max_freq;
 231         maple_cpu_freqs[1].frequency = max_freq/2;
 232
 233         /* Force apply current frequency to make sure everything is in
 234          * sync (voltage is right for example). Firmware may leave us with
 235          * a strange setting ...
 236          */
 237         msleep(10);
 238         maple_pmode_cur = -1;
 239         maple_scom_switch_freq(maple_scom_query_freq());
 240
 241         printk(KERN_INFO "Registering Maple CPU frequency driver\n");
 242         printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
 243                 maple_cpu_freqs[1].frequency/1000,
 244                 maple_cpu_freqs[0].frequency/1000,
 245                 maple_cpu_freqs[maple_pmode_cur].frequency/1000);
 246
 247         rc = cpufreq_register_driver(&maple_cpufreq_driver);
 248
 249         of_node_put(cpunode);
 250
 251         return rc;
 252
 253 bail_noprops:
 254         of_node_put(cpunode);
 255
 256         return rc;
 257 }
 258
 259 module_init(maple_cpufreq_init);
 260
 261
 262 MODULE_LICENSE("GPL");