diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/cpufreq/elanfreq.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/cpufreq/elanfreq.c b/drivers/cpufreq/elanfreq.c new file mode 100644 index 000000000..4ce5eb35d --- /dev/null +++ b/drivers/cpufreq/elanfreq.c @@ -0,0 +1,228 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * elanfreq: cpufreq driver for the AMD ELAN family + * + * (c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de> + * + * Parts of this code are (c) Sven Geggus <sven@geggus.net> + * + * All Rights Reserved. + * + * 2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> + +#include <linux/delay.h> +#include <linux/cpufreq.h> + +#include <asm/cpu_device_id.h> +#include <asm/msr.h> +#include <linux/timex.h> +#include <linux/io.h> + +#define REG_CSCIR 0x22 /* Chip Setup and Control Index Register */ +#define REG_CSCDR 0x23 /* Chip Setup and Control Data Register */ + +/* Module parameter */ +static int max_freq; + +struct s_elan_multiplier { + int clock; /* frequency in kHz */ + int val40h; /* PMU Force Mode register */ + int val80h; /* CPU Clock Speed Register */ +}; + +/* + * It is important that the frequencies + * are listed in ascending order here! + */ +static struct s_elan_multiplier elan_multiplier[] = { + {1000, 0x02, 0x18}, + {2000, 0x02, 0x10}, + {4000, 0x02, 0x08}, + {8000, 0x00, 0x00}, + {16000, 0x00, 0x02}, + {33000, 0x00, 0x04}, + {66000, 0x01, 0x04}, + {99000, 0x01, 0x05} +}; + +static struct cpufreq_frequency_table elanfreq_table[] = { + {0, 0, 1000}, + {0, 1, 2000}, + {0, 2, 4000}, + {0, 3, 8000}, + {0, 4, 16000}, + {0, 5, 33000}, + {0, 6, 66000}, + {0, 7, 99000}, + {0, 0, CPUFREQ_TABLE_END}, +}; + + +/** + * elanfreq_get_cpu_frequency: determine current cpu speed + * + * Finds out at which frequency the CPU of the Elan SOC runs + * at the moment. Frequencies from 1 to 33 MHz are generated + * the normal way, 66 and 99 MHz are called "Hyperspeed Mode" + * and have the rest of the chip running with 33 MHz. + */ + +static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu) +{ + u8 clockspeed_reg; /* Clock Speed Register */ + + local_irq_disable(); + outb_p(0x80, REG_CSCIR); + clockspeed_reg = inb_p(REG_CSCDR); + local_irq_enable(); + + if ((clockspeed_reg & 0xE0) == 0xE0) + return 0; + + /* Are we in CPU clock multiplied mode (66/99 MHz)? */ + if ((clockspeed_reg & 0xE0) == 0xC0) { + if ((clockspeed_reg & 0x01) == 0) + return 66000; + else + return 99000; + } + + /* 33 MHz is not 32 MHz... */ + if ((clockspeed_reg & 0xE0) == 0xA0) + return 33000; + + return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000; +} + + +static int elanfreq_target(struct cpufreq_policy *policy, + unsigned int state) +{ + /* + * Access to the Elan's internal registers is indexed via + * 0x22: Chip Setup & Control Register Index Register (CSCI) + * 0x23: Chip Setup & Control Register Data Register (CSCD) + * + */ + + /* + * 0x40 is the Power Management Unit's Force Mode Register. + * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency) + */ + + local_irq_disable(); + outb_p(0x40, REG_CSCIR); /* Disable hyperspeed mode */ + outb_p(0x00, REG_CSCDR); + local_irq_enable(); /* wait till internal pipelines and */ + udelay(1000); /* buffers have cleaned up */ + + local_irq_disable(); + + /* now, set the CPU clock speed register (0x80) */ + outb_p(0x80, REG_CSCIR); + outb_p(elan_multiplier[state].val80h, REG_CSCDR); + + /* now, the hyperspeed bit in PMU Force Mode Register (0x40) */ + outb_p(0x40, REG_CSCIR); + outb_p(elan_multiplier[state].val40h, REG_CSCDR); + udelay(10000); + local_irq_enable(); + + return 0; +} +/* + * Module init and exit code + */ + +static int elanfreq_cpu_init(struct cpufreq_policy *policy) +{ + struct cpuinfo_x86 *c = &cpu_data(0); + struct cpufreq_frequency_table *pos; + + /* capability check */ + if ((c->x86_vendor != X86_VENDOR_AMD) || + (c->x86 != 4) || (c->x86_model != 10)) + return -ENODEV; + + /* max freq */ + if (!max_freq) + max_freq = elanfreq_get_cpu_frequency(0); + + /* table init */ + cpufreq_for_each_entry(pos, elanfreq_table) + if (pos->frequency > max_freq) + pos->frequency = CPUFREQ_ENTRY_INVALID; + + policy->freq_table = elanfreq_table; + return 0; +} + + +#ifndef MODULE +/** + * elanfreq_setup - elanfreq command line parameter parsing + * + * elanfreq command line parameter. Use: + * elanfreq=66000 + * to set the maximum CPU frequency to 66 MHz. Note that in + * case you do not give this boot parameter, the maximum + * frequency will fall back to _current_ CPU frequency which + * might be lower. If you build this as a module, use the + * max_freq module parameter instead. + */ +static int __init elanfreq_setup(char *str) +{ + max_freq = simple_strtoul(str, &str, 0); + pr_warn("You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n"); + return 1; +} +__setup("elanfreq=", elanfreq_setup); +#endif + + +static struct cpufreq_driver elanfreq_driver = { + .get = elanfreq_get_cpu_frequency, + .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = elanfreq_target, + .init = elanfreq_cpu_init, + .name = "elanfreq", + .attr = cpufreq_generic_attr, +}; + +static const struct x86_cpu_id elan_id[] = { + X86_MATCH_VENDOR_FAM_MODEL(AMD, 4, 10, NULL), + {} +}; +MODULE_DEVICE_TABLE(x86cpu, elan_id); + +static int __init elanfreq_init(void) +{ + if (!x86_match_cpu(elan_id)) + return -ENODEV; + return cpufreq_register_driver(&elanfreq_driver); +} + + +static void __exit elanfreq_exit(void) +{ + cpufreq_unregister_driver(&elanfreq_driver); +} + + +module_param(max_freq, int, 0444); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, " + "Sven Geggus <sven@geggus.net>"); +MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs"); + +module_init(elanfreq_init); +module_exit(elanfreq_exit); |