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Diffstat (limited to '')
| -rw-r--r-- | drivers/cpufreq/speedstep-smi.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/drivers/cpufreq/speedstep-smi.c b/drivers/cpufreq/speedstep-smi.c new file mode 100644 index 000000000..0ce9d4b6d --- /dev/null +++ b/drivers/cpufreq/speedstep-smi.c @@ -0,0 +1,393 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Intel SpeedStep SMI driver. + * + * (C) 2003 Hiroshi Miura <miura@da-cha.org> + */ + + +/********************************************************************* + * SPEEDSTEP - DEFINITIONS * + *********************************************************************/ + +#define pr_fmt(fmt) "cpufreq: " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <asm/ist.h> +#include <asm/cpu_device_id.h> + +#include "speedstep-lib.h" + +/* speedstep system management interface port/command. + * + * These parameters are got from IST-SMI BIOS call. + * If user gives it, these are used. + * + */ +static int smi_port; +static int smi_cmd; +static unsigned int smi_sig; + +/* info about the processor */ +static enum speedstep_processor speedstep_processor; + +/* + * There are only two frequency states for each processor. Values + * are in kHz for the time being. + */ +static struct cpufreq_frequency_table speedstep_freqs[] = { + {0, SPEEDSTEP_HIGH, 0}, + {0, SPEEDSTEP_LOW, 0}, + {0, 0, CPUFREQ_TABLE_END}, +}; + +#define GET_SPEEDSTEP_OWNER 0 +#define GET_SPEEDSTEP_STATE 1 +#define SET_SPEEDSTEP_STATE 2 +#define GET_SPEEDSTEP_FREQS 4 + +/* how often shall the SMI call be tried if it failed, e.g. because + * of DMA activity going on? */ +#define SMI_TRIES 5 + +/** + * speedstep_smi_ownership + */ +static int speedstep_smi_ownership(void) +{ + u32 command, result, magic, dummy; + u32 function = GET_SPEEDSTEP_OWNER; + unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation"; + + command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff); + magic = virt_to_phys(magic_data); + + pr_debug("trying to obtain ownership with command %x at port %x\n", + command, smi_port); + + __asm__ __volatile__( + "push %%ebp\n" + "out %%al, (%%dx)\n" + "pop %%ebp\n" + : "=D" (result), + "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy), + "=S" (dummy) + : "a" (command), "b" (function), "c" (0), "d" (smi_port), + "D" (0), "S" (magic) + : "memory" + ); + + pr_debug("result is %x\n", result); + + return result; +} + +/** + * speedstep_smi_get_freqs - get SpeedStep preferred & current freq. + * @low: the low frequency value is placed here + * @high: the high frequency value is placed here + * + * Only available on later SpeedStep-enabled systems, returns false results or + * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing + * shows that the latter occurs if !(ist_info.event & 0xFFFF). + */ +static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high) +{ + u32 command, result = 0, edi, high_mhz, low_mhz, dummy; + u32 state = 0; + u32 function = GET_SPEEDSTEP_FREQS; + + if (!(ist_info.event & 0xFFFF)) { + pr_debug("bug #1422 -- can't read freqs from BIOS\n"); + return -ENODEV; + } + + command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff); + + pr_debug("trying to determine frequencies with command %x at port %x\n", + command, smi_port); + + __asm__ __volatile__( + "push %%ebp\n" + "out %%al, (%%dx)\n" + "pop %%ebp" + : "=a" (result), + "=b" (high_mhz), + "=c" (low_mhz), + "=d" (state), "=D" (edi), "=S" (dummy) + : "a" (command), + "b" (function), + "c" (state), + "d" (smi_port), "S" (0), "D" (0) + ); + + pr_debug("result %x, low_freq %u, high_freq %u\n", + result, low_mhz, high_mhz); + + /* abort if results are obviously incorrect... */ + if ((high_mhz + low_mhz) < 600) + return -EINVAL; + + *high = high_mhz * 1000; + *low = low_mhz * 1000; + + return result; +} + +/** + * speedstep_set_state - set the SpeedStep state + * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH) + * + */ +static void speedstep_set_state(unsigned int state) +{ + unsigned int result = 0, command, new_state, dummy; + unsigned long flags; + unsigned int function = SET_SPEEDSTEP_STATE; + unsigned int retry = 0; + + if (state > 0x1) + return; + + /* Disable IRQs */ + preempt_disable(); + local_irq_save(flags); + + command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff); + + pr_debug("trying to set frequency to state %u " + "with command %x at port %x\n", + state, command, smi_port); + + do { + if (retry) { + /* + * We need to enable interrupts, otherwise the blockage + * won't resolve. + * + * We disable preemption so that other processes don't + * run. If other processes were running, they could + * submit more DMA requests, making the blockage worse. + */ + pr_debug("retry %u, previous result %u, waiting...\n", + retry, result); + local_irq_enable(); + mdelay(retry * 50); + local_irq_disable(); + } + retry++; + __asm__ __volatile__( + "push %%ebp\n" + "out %%al, (%%dx)\n" + "pop %%ebp" + : "=b" (new_state), "=D" (result), + "=c" (dummy), "=a" (dummy), + "=d" (dummy), "=S" (dummy) + : "a" (command), "b" (function), "c" (state), + "d" (smi_port), "S" (0), "D" (0) + ); + } while ((new_state != state) && (retry <= SMI_TRIES)); + + /* enable IRQs */ + local_irq_restore(flags); + preempt_enable(); + + if (new_state == state) + pr_debug("change to %u MHz succeeded after %u tries " + "with result %u\n", + (speedstep_freqs[new_state].frequency / 1000), + retry, result); + else + pr_err("change to state %u failed with new_state %u and result %u\n", + state, new_state, result); + + return; +} + + +/** + * speedstep_target - set a new CPUFreq policy + * @policy: new policy + * @index: index of new freq + * + * Sets a new CPUFreq policy/freq. + */ +static int speedstep_target(struct cpufreq_policy *policy, unsigned int index) +{ + speedstep_set_state(index); + + return 0; +} + + +static int speedstep_cpu_init(struct cpufreq_policy *policy) +{ + int result; + unsigned int *low, *high; + + /* capability check */ + if (policy->cpu != 0) + return -ENODEV; + + result = speedstep_smi_ownership(); + if (result) { + pr_debug("fails in acquiring ownership of a SMI interface.\n"); + return -EINVAL; + } + + /* detect low and high frequency */ + low = &speedstep_freqs[SPEEDSTEP_LOW].frequency; + high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency; + + result = speedstep_smi_get_freqs(low, high); + if (result) { + /* fall back to speedstep_lib.c dection mechanism: + * try both states out */ + pr_debug("could not detect low and high frequencies " + "by SMI call.\n"); + result = speedstep_get_freqs(speedstep_processor, + low, high, + NULL, + &speedstep_set_state); + + if (result) { + pr_debug("could not detect two different speeds" + " -- aborting.\n"); + return result; + } else + pr_debug("workaround worked.\n"); + } + + policy->freq_table = speedstep_freqs; + + return 0; +} + +static unsigned int speedstep_get(unsigned int cpu) +{ + if (cpu) + return -ENODEV; + return speedstep_get_frequency(speedstep_processor); +} + + +static int speedstep_resume(struct cpufreq_policy *policy) +{ + int result = speedstep_smi_ownership(); + + if (result) + pr_debug("fails in re-acquiring ownership of a SMI interface.\n"); + + return result; +} + +static struct cpufreq_driver speedstep_driver = { + .name = "speedstep-smi", + .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = speedstep_target, + .init = speedstep_cpu_init, + .get = speedstep_get, + .resume = speedstep_resume, + .attr = cpufreq_generic_attr, +}; + +static const struct x86_cpu_id ss_smi_ids[] = { + X86_MATCH_VENDOR_FAM_MODEL(INTEL, 6, 0x8, 0), + X86_MATCH_VENDOR_FAM_MODEL(INTEL, 6, 0xb, 0), + X86_MATCH_VENDOR_FAM_MODEL(INTEL, 15, 0x2, 0), + {} +}; + +/** + * speedstep_init - initializes the SpeedStep CPUFreq driver + * + * Initializes the SpeedStep support. Returns -ENODEV on unsupported + * BIOS, -EINVAL on problems during initiatization, and zero on + * success. + */ +static int __init speedstep_init(void) +{ + if (!x86_match_cpu(ss_smi_ids)) + return -ENODEV; + + speedstep_processor = speedstep_detect_processor(); + + switch (speedstep_processor) { + case SPEEDSTEP_CPU_PIII_T: + case SPEEDSTEP_CPU_PIII_C: + case SPEEDSTEP_CPU_PIII_C_EARLY: + break; + default: + speedstep_processor = 0; + } + + if (!speedstep_processor) { + pr_debug("No supported Intel CPU detected.\n"); + return -ENODEV; + } + + pr_debug("signature:0x%.8x, command:0x%.8x, " + "event:0x%.8x, perf_level:0x%.8x.\n", + ist_info.signature, ist_info.command, + ist_info.event, ist_info.perf_level); + + /* Error if no IST-SMI BIOS or no PARM + sig= 'ISGE' aka 'Intel Speedstep Gate E' */ + if ((ist_info.signature != 0x47534943) && ( + (smi_port == 0) || (smi_cmd == 0))) + return -ENODEV; + + if (smi_sig == 1) + smi_sig = 0x47534943; + else + smi_sig = ist_info.signature; + + /* setup smi_port from MODLULE_PARM or BIOS */ + if ((smi_port > 0xff) || (smi_port < 0)) + return -EINVAL; + else if (smi_port == 0) + smi_port = ist_info.command & 0xff; + + if ((smi_cmd > 0xff) || (smi_cmd < 0)) + return -EINVAL; + else if (smi_cmd == 0) + smi_cmd = (ist_info.command >> 16) & 0xff; + + return cpufreq_register_driver(&speedstep_driver); +} + + +/** + * speedstep_exit - unregisters SpeedStep support + * + * Unregisters SpeedStep support. + */ +static void __exit speedstep_exit(void) +{ + cpufreq_unregister_driver(&speedstep_driver); +} + +module_param_hw(smi_port, int, ioport, 0444); +module_param(smi_cmd, int, 0444); +module_param(smi_sig, uint, 0444); + +MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value " + "-- Intel's default setting is 0xb2"); +MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value " + "-- Intel's default setting is 0x82"); +MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the " + "SMI interface."); + +MODULE_AUTHOR("Hiroshi Miura"); +MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface."); +MODULE_LICENSE("GPL"); + +module_init(speedstep_init); +module_exit(speedstep_exit); |