1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2011 Dmitry Eremin-Solenikov 4 * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org> 5 * and Markus Demleitner <msdemlei@cl.uni-heidelberg.de> 6 * 7 * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs, 8 * that is iMac G5 and latest single CPU desktop. 9 */ 10 11 #undef DEBUG 12 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 14 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <linux/errno.h> 18 #include <linux/kernel.h> 19 #include <linux/delay.h> 20 #include <linux/sched.h> 21 #include <linux/cpufreq.h> 22 #include <linux/init.h> 23 #include <linux/completion.h> 24 #include <linux/mutex.h> 25 #include <linux/time.h> 26 #include <linux/of_device.h> 27 28 #define DBG(fmt...) pr_debug(fmt) 29 30 /* see 970FX user manual */ 31 32 #define SCOM_PCR 0x0aa001 /* PCR scom addr */ 33 34 #define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */ 35 #define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */ 36 #define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */ 37 #define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */ 38 #define PCR_SPEED_MASK 0x000e0000U /* speed mask */ 39 #define PCR_SPEED_SHIFT 17 40 #define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */ 41 #define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */ 42 #define PCR_TARGET_TIME_MASK 0x00006000U /* target time */ 43 #define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */ 44 #define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */ 45 #define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */ 46 47 #define SCOM_PSR 0x408001 /* PSR scom addr */ 48 /* warning: PSR is a 64 bits register */ 49 #define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */ 50 #define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */ 51 #define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */ 52 #define PSR_CUR_SPEED_SHIFT (56) 53 54 /* 55 * The G5 only supports two frequencies (Quarter speed is not supported) 56 */ 57 #define CPUFREQ_HIGH 0 58 #define CPUFREQ_LOW 1 59 60 static struct cpufreq_frequency_table maple_cpu_freqs[] = { 61 {0, CPUFREQ_HIGH, 0}, 62 {0, CPUFREQ_LOW, 0}, 63 {0, 0, CPUFREQ_TABLE_END}, 64 }; 65 66 /* Power mode data is an array of the 32 bits PCR values to use for 67 * the various frequencies, retrieved from the device-tree 68 */ 69 static int maple_pmode_cur; 70 71 static const u32 *maple_pmode_data; 72 static int maple_pmode_max; 73 74 /* 75 * SCOM based frequency switching for 970FX rev3 76 */ 77 static int maple_scom_switch_freq(int speed_mode) 78 { 79 unsigned long flags; 80 int to; 81 82 local_irq_save(flags); 83 84 /* Clear PCR high */ 85 scom970_write(SCOM_PCR, 0); 86 /* Clear PCR low */ 87 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0); 88 /* Set PCR low */ 89 scom970_write(SCOM_PCR, PCR_HILO_SELECT | 90 maple_pmode_data[speed_mode]); 91 92 /* Wait for completion */ 93 for (to = 0; to < 10; to++) { 94 unsigned long psr = scom970_read(SCOM_PSR); 95 96 if ((psr & PSR_CMD_RECEIVED) == 0 && 97 (((psr >> PSR_CUR_SPEED_SHIFT) ^ 98 (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3) 99 == 0) 100 break; 101 if (psr & PSR_CMD_COMPLETED) 102 break; 103 udelay(100); 104 } 105 106 local_irq_restore(flags); 107 108 maple_pmode_cur = speed_mode; 109 ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul; 110 111 return 0; 112 } 113 114 static int maple_scom_query_freq(void) 115 { 116 unsigned long psr = scom970_read(SCOM_PSR); 117 int i; 118 119 for (i = 0; i <= maple_pmode_max; i++) 120 if ((((psr >> PSR_CUR_SPEED_SHIFT) ^ 121 (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0) 122 break; 123 return i; 124 } 125 126 /* 127 * Common interface to the cpufreq core 128 */ 129 130 static int maple_cpufreq_target(struct cpufreq_policy *policy, 131 unsigned int index) 132 { 133 return maple_scom_switch_freq(index); 134 } 135 136 static unsigned int maple_cpufreq_get_speed(unsigned int cpu) 137 { 138 return maple_cpu_freqs[maple_pmode_cur].frequency; 139 } 140 141 static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) 142 { 143 return cpufreq_generic_init(policy, maple_cpu_freqs, 12000); 144 } 145 146 static struct cpufreq_driver maple_cpufreq_driver = { 147 .name = "maple", 148 .flags = CPUFREQ_CONST_LOOPS, 149 .init = maple_cpufreq_cpu_init, 150 .verify = cpufreq_generic_frequency_table_verify, 151 .target_index = maple_cpufreq_target, 152 .get = maple_cpufreq_get_speed, 153 .attr = cpufreq_generic_attr, 154 }; 155 156 static int __init maple_cpufreq_init(void) 157 { 158 struct device_node *cpunode; 159 unsigned int psize; 160 unsigned long max_freq; 161 const u32 *valp; 162 u32 pvr_hi; 163 int rc = -ENODEV; 164 165 /* 166 * Behave here like powermac driver which checks machine compatibility 167 * to ease merging of two drivers in future. 168 */ 169 if (!of_machine_is_compatible("Momentum,Maple") && 170 !of_machine_is_compatible("Momentum,Apache")) 171 return 0; 172 173 /* Get first CPU node */ 174 cpunode = of_cpu_device_node_get(0); 175 if (cpunode == NULL) { 176 pr_err("Can't find any CPU 0 node\n"); 177 goto bail_noprops; 178 } 179 180 /* Check 970FX for now */ 181 /* we actually don't care on which CPU to access PVR */ 182 pvr_hi = PVR_VER(mfspr(SPRN_PVR)); 183 if (pvr_hi != 0x3c && pvr_hi != 0x44) { 184 pr_err("Unsupported CPU version (%x)\n", pvr_hi); 185 goto bail_noprops; 186 } 187 188 /* Look for the powertune data in the device-tree */ 189 /* 190 * On Maple this property is provided by PIBS in dual-processor config, 191 * not provided by PIBS in CPU0 config and also not provided by SLOF, 192 * so YMMV 193 */ 194 maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); 195 if (!maple_pmode_data) { 196 DBG("No power-mode-data !\n"); 197 goto bail_noprops; 198 } 199 maple_pmode_max = psize / sizeof(u32) - 1; 200 201 /* 202 * From what I see, clock-frequency is always the maximal frequency. 203 * The current driver can not slew sysclk yet, so we really only deal 204 * with powertune steps for now. We also only implement full freq and 205 * half freq in this version. So far, I haven't yet seen a machine 206 * supporting anything else. 207 */ 208 valp = of_get_property(cpunode, "clock-frequency", NULL); 209 if (!valp) 210 goto bail_noprops; 211 max_freq = (*valp)/1000; 212 maple_cpu_freqs[0].frequency = max_freq; 213 maple_cpu_freqs[1].frequency = max_freq/2; 214 215 /* Force apply current frequency to make sure everything is in 216 * sync (voltage is right for example). Firmware may leave us with 217 * a strange setting ... 218 */ 219 msleep(10); 220 maple_pmode_cur = -1; 221 maple_scom_switch_freq(maple_scom_query_freq()); 222 223 pr_info("Registering Maple CPU frequency driver\n"); 224 pr_info("Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", 225 maple_cpu_freqs[1].frequency/1000, 226 maple_cpu_freqs[0].frequency/1000, 227 maple_cpu_freqs[maple_pmode_cur].frequency/1000); 228 229 rc = cpufreq_register_driver(&maple_cpufreq_driver); 230 231 bail_noprops: 232 of_node_put(cpunode); 233 234 return rc; 235 } 236 237 module_init(maple_cpufreq_init); 238 239 240 MODULE_LICENSE("GPL"); 241