diff options
Diffstat (limited to 'drivers/cpufreq/maple-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/maple-cpufreq.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/drivers/cpufreq/maple-cpufreq.c b/drivers/cpufreq/maple-cpufreq.c new file mode 100644 index 0000000000..f9306410a0 --- /dev/null +++ b/drivers/cpufreq/maple-cpufreq.c @@ -0,0 +1,241 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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 driver adds basic cpufreq support for SMU & 970FX based G5 Macs, + * that is iMac G5 and latest single CPU desktop. + */ + +#undef DEBUG + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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[] = { + {0, CPUFREQ_HIGH, 0}, + {0, CPUFREQ_LOW, 0}, + {0, 0, CPUFREQ_TABLE_END}, +}; + +/* 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 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_target(struct cpufreq_policy *policy, + unsigned int index) +{ + return maple_scom_switch_freq(index); +} + +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) +{ + cpufreq_generic_init(policy, maple_cpu_freqs, 12000); + return 0; +} + +static struct cpufreq_driver maple_cpufreq_driver = { + .name = "maple", + .flags = CPUFREQ_CONST_LOOPS, + .init = maple_cpufreq_cpu_init, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = maple_cpufreq_target, + .get = maple_cpufreq_get_speed, + .attr = cpufreq_generic_attr, +}; + +static int __init maple_cpufreq_init(void) +{ + 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; + + /* Get first CPU node */ + cpunode = of_cpu_device_node_get(0); + if (cpunode == NULL) { + pr_err("Can't find any CPU 0 node\n"); + goto bail_noprops; + } + + /* 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) { + pr_err("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) + goto bail_noprops; + 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()); + + pr_info("Registering Maple CPU frequency driver\n"); + pr_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); + +bail_noprops: + of_node_put(cpunode); + + return rc; +} + +module_init(maple_cpufreq_init); + + +MODULE_LICENSE("GPL"); |