maple-cpufreq.c (6658B)
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 60static 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 */ 69static int maple_pmode_cur; 70 71static const u32 *maple_pmode_data; 72static int maple_pmode_max; 73 74/* 75 * SCOM based frequency switching for 970FX rev3 76 */ 77static 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 114static 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 130static int maple_cpufreq_target(struct cpufreq_policy *policy, 131 unsigned int index) 132{ 133 return maple_scom_switch_freq(index); 134} 135 136static unsigned int maple_cpufreq_get_speed(unsigned int cpu) 137{ 138 return maple_cpu_freqs[maple_pmode_cur].frequency; 139} 140 141static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) 142{ 143 cpufreq_generic_init(policy, maple_cpu_freqs, 12000); 144 return 0; 145} 146 147static 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 157static 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 pr_err("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 pr_err("Unsupported CPU version (%x)\n", pvr_hi); 186 goto bail_noprops; 187 } 188 189 /* Look for the powertune data in the device-tree */ 190 /* 191 * On Maple this property is provided by PIBS in dual-processor config, 192 * not provided by PIBS in CPU0 config and also not provided by SLOF, 193 * so YMMV 194 */ 195 maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); 196 if (!maple_pmode_data) { 197 DBG("No power-mode-data !\n"); 198 goto bail_noprops; 199 } 200 maple_pmode_max = psize / sizeof(u32) - 1; 201 202 /* 203 * From what I see, clock-frequency is always the maximal frequency. 204 * The current driver can not slew sysclk yet, so we really only deal 205 * with powertune steps for now. We also only implement full freq and 206 * half freq in this version. So far, I haven't yet seen a machine 207 * supporting anything else. 208 */ 209 valp = of_get_property(cpunode, "clock-frequency", NULL); 210 if (!valp) 211 goto bail_noprops; 212 max_freq = (*valp)/1000; 213 maple_cpu_freqs[0].frequency = max_freq; 214 maple_cpu_freqs[1].frequency = max_freq/2; 215 216 /* Force apply current frequency to make sure everything is in 217 * sync (voltage is right for example). Firmware may leave us with 218 * a strange setting ... 219 */ 220 msleep(10); 221 maple_pmode_cur = -1; 222 maple_scom_switch_freq(maple_scom_query_freq()); 223 224 pr_info("Registering Maple CPU frequency driver\n"); 225 pr_info("Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", 226 maple_cpu_freqs[1].frequency/1000, 227 maple_cpu_freqs[0].frequency/1000, 228 maple_cpu_freqs[maple_pmode_cur].frequency/1000); 229 230 rc = cpufreq_register_driver(&maple_cpufreq_driver); 231 232bail_noprops: 233 of_node_put(cpunode); 234 235 return rc; 236} 237 238module_init(maple_cpufreq_init); 239 240 241MODULE_LICENSE("GPL");