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 {0, CPUFREQ_HIGH, 0}, 63 {0, CPUFREQ_LOW, 0}, 64 {0, 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 const u32 *maple_pmode_data; 73 static int maple_pmode_max; 74 75 /* 76 * SCOM based frequency switching for 970FX rev3 77 */ 78 static int maple_scom_switch_freq(int speed_mode) 79 { 80 unsigned long flags; 81 int to; 82 83 local_irq_save(flags); 84 85 /* Clear PCR high */ 86 scom970_write(SCOM_PCR, 0); 87 /* Clear PCR low */ 88 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0); 89 /* Set PCR low */ 90 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 91 maple_pmode_data[speed_mode]); 92 93 /* Wait for completion */ 94 for (to = 0; to < 10; to++) { 95 unsigned long psr = scom970_read(SCOM_PSR); 96 97 if ((psr & PSR_CMD_RECEIVED) == 0 && 98 (((psr >> PSR_CUR_SPEED_SHIFT) ^ 99 (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3) 100 == 0) 101 break; 102 if (psr & PSR_CMD_COMPLETED) 103 break; 104 udelay(100); 105 } 106 107 local_irq_restore(flags); 108 109 maple_pmode_cur = speed_mode; 110 ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul; 111 112 return 0; 113 } 114 115 static int maple_scom_query_freq(void) 116 { 117 unsigned long psr = scom970_read(SCOM_PSR); 118 int i; 119 120 for (i = 0; i <= maple_pmode_max; i++) 121 if ((((psr >> PSR_CUR_SPEED_SHIFT) ^ 122 (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0) 123 break; 124 return i; 125 } 126 127 /* 128 * Common interface to the cpufreq core 129 */ 130 131 static int maple_cpufreq_target(struct cpufreq_policy *policy, 132 unsigned int index) 133 { 134 return maple_scom_switch_freq(index); 135 } 136 137 static unsigned int maple_cpufreq_get_speed(unsigned int cpu) 138 { 139 return maple_cpu_freqs[maple_pmode_cur].frequency; 140 } 141 142 static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) 143 { 144 return cpufreq_generic_init(policy, maple_cpu_freqs, 12000); 145 } 146 147 static struct cpufreq_driver maple_cpufreq_driver = { 148 .name = "maple", 149 .flags = CPUFREQ_CONST_LOOPS, 150 .init = maple_cpufreq_cpu_init, 151 .verify = cpufreq_generic_frequency_table_verify, 152 .target_index = maple_cpufreq_target, 153 .get = maple_cpufreq_get_speed, 154 .attr = cpufreq_generic_attr, 155 }; 156 157 static int __init maple_cpufreq_init(void) 158 { 159 struct device_node *cpunode; 160 unsigned int psize; 161 unsigned long max_freq; 162 const u32 *valp; 163 u32 pvr_hi; 164 int rc = -ENODEV; 165 166 /* 167 * Behave here like powermac driver which checks machine compatibility 168 * to ease merging of two drivers in future. 169 */ 170 if (!of_machine_is_compatible("Momentum,Maple") && 171 !of_machine_is_compatible("Momentum,Apache")) 172 return 0; 173 174 /* Get first CPU node */ 175 cpunode = of_cpu_device_node_get(0); 176 if (cpunode == NULL) { 177 printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n"); 178 goto bail_noprops; 179 } 180 181 /* Check 970FX for now */ 182 /* we actually don't care on which CPU to access PVR */ 183 pvr_hi = PVR_VER(mfspr(SPRN_PVR)); 184 if (pvr_hi != 0x3c && pvr_hi != 0x44) { 185 printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n", 186 pvr_hi); 187 goto bail_noprops; 188 } 189 190 /* Look for the powertune data in the device-tree */ 191 /* 192 * On Maple this property is provided by PIBS in dual-processor config, 193 * not provided by PIBS in CPU0 config and also not provided by SLOF, 194 * so YMMV 195 */ 196 maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); 197 if (!maple_pmode_data) { 198 DBG("No power-mode-data !\n"); 199 goto bail_noprops; 200 } 201 maple_pmode_max = psize / sizeof(u32) - 1; 202 203 /* 204 * From what I see, clock-frequency is always the maximal frequency. 205 * The current driver can not slew sysclk yet, so we really only deal 206 * with powertune steps for now. We also only implement full freq and 207 * half freq in this version. So far, I haven't yet seen a machine 208 * supporting anything else. 209 */ 210 valp = of_get_property(cpunode, "clock-frequency", NULL); 211 if (!valp) 212 return -ENODEV; 213 max_freq = (*valp)/1000; 214 maple_cpu_freqs[0].frequency = max_freq; 215 maple_cpu_freqs[1].frequency = max_freq/2; 216 217 /* Force apply current frequency to make sure everything is in 218 * sync (voltage is right for example). Firmware may leave us with 219 * a strange setting ... 220 */ 221 msleep(10); 222 maple_pmode_cur = -1; 223 maple_scom_switch_freq(maple_scom_query_freq()); 224 225 printk(KERN_INFO "Registering Maple CPU frequency driver\n"); 226 printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", 227 maple_cpu_freqs[1].frequency/1000, 228 maple_cpu_freqs[0].frequency/1000, 229 maple_cpu_freqs[maple_pmode_cur].frequency/1000); 230 231 rc = cpufreq_register_driver(&maple_cpufreq_driver); 232 233 of_node_put(cpunode); 234 235 return rc; 236 237 bail_noprops: 238 of_node_put(cpunode); 239 240 return rc; 241 } 242 243 module_init(maple_cpufreq_init); 244 245 246 MODULE_LICENSE("GPL"); 247