/* * Copyright (C) 2011 Dmitry Eremin-Solenikov * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org> * and Markus Demleitner <msdemlei@cl.uni-heidelberg.de> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs, * that is iMac G5 and latest single CPU desktop. */ #undef DEBUG #include <linux/module.h> #include <linux/types.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/delay.h> #include <linux/sched.h> #include <linux/cpufreq.h> #include <linux/init.h> #include <linux/completion.h> #include <linux/mutex.h> #include <linux/time.h> #include <linux/of.h> #define DBG(fmt...) pr_debug(fmt) /* see 970FX user manual */ #define SCOM_PCR 0x0aa001 /* PCR scom addr */ #define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */ #define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */ #define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */ #define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */ #define PCR_SPEED_MASK 0x000e0000U /* speed mask */ #define PCR_SPEED_SHIFT 17 #define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */ #define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */ #define PCR_TARGET_TIME_MASK 0x00006000U /* target time */ #define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */ #define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */ #define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */ #define SCOM_PSR 0x408001 /* PSR scom addr */ /* warning: PSR is a 64 bits register */ #define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */ #define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */ #define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */ #define PSR_CUR_SPEED_SHIFT (56) /* * The G5 only supports two frequencies (Quarter speed is not supported) */ #define CPUFREQ_HIGH 0 #define CPUFREQ_LOW 1 static struct cpufreq_frequency_table maple_cpu_freqs[] = { {CPUFREQ_HIGH, 0}, {CPUFREQ_LOW, 0}, {0, CPUFREQ_TABLE_END}, }; static struct freq_attr *maple_cpu_freqs_attr[] = { &cpufreq_freq_attr_scaling_available_freqs, NULL, }; /* Power mode data is an array of the 32 bits PCR values to use for * the various frequencies, retrieved from the device-tree */ static int maple_pmode_cur; static DEFINE_MUTEX(maple_switch_mutex); static const u32 *maple_pmode_data; static int maple_pmode_max; /* * SCOM based frequency switching for 970FX rev3 */ static int maple_scom_switch_freq(int speed_mode) { unsigned long flags; int to; local_irq_save(flags); /* Clear PCR high */ scom970_write(SCOM_PCR, 0); /* Clear PCR low */ scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0); /* Set PCR low */ scom970_write(SCOM_PCR, PCR_HILO_SELECT | maple_pmode_data[speed_mode]); /* Wait for completion */ for (to = 0; to < 10; to++) { unsigned long psr = scom970_read(SCOM_PSR); if ((psr & PSR_CMD_RECEIVED) == 0 && (((psr >> PSR_CUR_SPEED_SHIFT) ^ (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3) == 0) break; if (psr & PSR_CMD_COMPLETED) break; udelay(100); } local_irq_restore(flags); maple_pmode_cur = speed_mode; ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul; return 0; } static int maple_scom_query_freq(void) { unsigned long psr = scom970_read(SCOM_PSR); int i; for (i = 0; i <= maple_pmode_max; i++) if ((((psr >> PSR_CUR_SPEED_SHIFT) ^ (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0) break; return i; } /* * Common interface to the cpufreq core */ static int maple_cpufreq_verify(struct cpufreq_policy *policy) { return cpufreq_frequency_table_verify(policy, maple_cpu_freqs); } static int maple_cpufreq_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { unsigned int newstate = 0; struct cpufreq_freqs freqs; int rc; if (cpufreq_frequency_table_target(policy, maple_cpu_freqs, target_freq, relation, &newstate)) return -EINVAL; if (maple_pmode_cur == newstate) return 0; mutex_lock(&maple_switch_mutex); freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency; freqs.new = maple_cpu_freqs[newstate].frequency; cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); rc = maple_scom_switch_freq(newstate); cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); mutex_unlock(&maple_switch_mutex); return rc; } static unsigned int maple_cpufreq_get_speed(unsigned int cpu) { return maple_cpu_freqs[maple_pmode_cur].frequency; } static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) { policy->cpuinfo.transition_latency = 12000; policy->cur = maple_cpu_freqs[maple_scom_query_freq()].frequency; /* secondary CPUs are tied to the primary one by the * cpufreq core if in the secondary policy we tell it that * it actually must be one policy together with all others. */ cpumask_setall(policy->cpus); cpufreq_frequency_table_get_attr(maple_cpu_freqs, policy->cpu); return cpufreq_frequency_table_cpuinfo(policy, maple_cpu_freqs); } static struct cpufreq_driver maple_cpufreq_driver = { .name = "maple", .owner = THIS_MODULE, .flags = CPUFREQ_CONST_LOOPS, .init = maple_cpufreq_cpu_init, .verify = maple_cpufreq_verify, .target = maple_cpufreq_target, .get = maple_cpufreq_get_speed, .attr = maple_cpu_freqs_attr, }; static int __init maple_cpufreq_init(void) { struct device_node *cpus; struct device_node *cpunode; unsigned int psize; unsigned long max_freq; const u32 *valp; u32 pvr_hi; int rc = -ENODEV; /* * Behave here like powermac driver which checks machine compatibility * to ease merging of two drivers in future. */ if (!of_machine_is_compatible("Momentum,Maple") && !of_machine_is_compatible("Momentum,Apache")) return 0; cpus = of_find_node_by_path("/cpus"); if (cpus == NULL) { DBG("No /cpus node !\n"); return -ENODEV; } /* Get first CPU node */ for (cpunode = NULL; (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) { const u32 *reg = of_get_property(cpunode, "reg", NULL); if (reg == NULL || (*reg) != 0) continue; if (!strcmp(cpunode->type, "cpu")) break; } if (cpunode == NULL) { printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n"); goto bail_cpus; } /* Check 970FX for now */ /* we actually don't care on which CPU to access PVR */ pvr_hi = PVR_VER(mfspr(SPRN_PVR)); if (pvr_hi != 0x3c && pvr_hi != 0x44) { printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n", pvr_hi); goto bail_noprops; } /* Look for the powertune data in the device-tree */ /* * On Maple this property is provided by PIBS in dual-processor config, * not provided by PIBS in CPU0 config and also not provided by SLOF, * so YMMV */ maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); if (!maple_pmode_data) { DBG("No power-mode-data !\n"); goto bail_noprops; } maple_pmode_max = psize / sizeof(u32) - 1; /* * From what I see, clock-frequency is always the maximal frequency. * The current driver can not slew sysclk yet, so we really only deal * with powertune steps for now. We also only implement full freq and * half freq in this version. So far, I haven't yet seen a machine * supporting anything else. */ valp = of_get_property(cpunode, "clock-frequency", NULL); if (!valp) return -ENODEV; max_freq = (*valp)/1000; maple_cpu_freqs[0].frequency = max_freq; maple_cpu_freqs[1].frequency = max_freq/2; /* Force apply current frequency to make sure everything is in * sync (voltage is right for example). Firmware may leave us with * a strange setting ... */ msleep(10); maple_pmode_cur = -1; maple_scom_switch_freq(maple_scom_query_freq()); printk(KERN_INFO "Registering Maple CPU frequency driver\n"); printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", maple_cpu_freqs[1].frequency/1000, maple_cpu_freqs[0].frequency/1000, maple_cpu_freqs[maple_pmode_cur].frequency/1000); rc = cpufreq_register_driver(&maple_cpufreq_driver); of_node_put(cpunode); of_node_put(cpus); return rc; bail_noprops: of_node_put(cpunode); bail_cpus: of_node_put(cpus); return rc; } module_init(maple_cpufreq_init); MODULE_LICENSE("GPL");