From 0a248af6e18d7f1ad57fffa7f588bc8a5851832e Mon Sep 17 00:00:00 2001 From: popcornmix Date: Wed, 3 Jul 2013 00:49:20 +0100 Subject: [PATCH] Add cpufreq driver Signed-off-by: popcornmix bcm2835-cpufreq: Change licence to GPLv2 Signed-off-by: Eben Upton Signed-off-by: Dom Cobley --- drivers/cpufreq/Kconfig.arm | 9 ++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/bcm2835-cpufreq.c | 210 ++++++++++++++++++++++++++++++ 3 files changed, 220 insertions(+) create mode 100644 drivers/cpufreq/bcm2835-cpufreq.c --- a/drivers/cpufreq/Kconfig.arm +++ b/drivers/cpufreq/Kconfig.arm @@ -260,6 +260,15 @@ config ARM_TANGO_CPUFREQ depends on CPUFREQ_DT && ARCH_TANGO default y +config ARM_BCM2835_CPUFREQ + depends on RASPBERRYPI_FIRMWARE + bool "BCM2835 Driver" + default y + help + This adds the CPUFreq driver for BCM2835 + + If in doubt, say N. + config ARM_TEGRA20_CPUFREQ tristate "Tegra20 CPUFreq support" depends on ARCH_TEGRA --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -80,6 +80,7 @@ obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi- obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o obj-$(CONFIG_ARM_STI_CPUFREQ) += sti-cpufreq.o obj-$(CONFIG_ARM_TANGO_CPUFREQ) += tango-cpufreq.o +obj-$(CONFIG_ARM_BCM2835_CPUFREQ) += bcm2835-cpufreq.o obj-$(CONFIG_ARM_TEGRA20_CPUFREQ) += tegra20-cpufreq.o obj-$(CONFIG_ARM_TEGRA124_CPUFREQ) += tegra124-cpufreq.o obj-$(CONFIG_ARM_TEGRA186_CPUFREQ) += tegra186-cpufreq.o --- /dev/null +++ b/drivers/cpufreq/bcm2835-cpufreq.c @@ -0,0 +1,210 @@ +/* + * Copyright 2011 Broadcom Corporation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + * + * This driver dynamically manages the CPU Frequency of the ARM + * processor. Messages are sent to Videocore either setting or requesting the + * frequency of the ARM in order to match an appropiate frequency to the current + * usage of the processor. The policy which selects the frequency to use is + * defined in the kernel .config file, but can be changed during runtime. + */ + +/* ---------- INCLUDES ---------- */ +#include +#include +#include +#include +#include + +/* ---------- DEFINES ---------- */ +/*#define CPUFREQ_DEBUG_ENABLE*/ /* enable debugging */ +#define MODULE_NAME "bcm2835-cpufreq" + +#define VCMSG_ID_ARM_CLOCK 0x000000003 /* Clock/Voltage ID's */ + +/* debug printk macros */ +#ifdef CPUFREQ_DEBUG_ENABLE +#define print_debug(fmt,...) pr_debug("%s:%s:%d: "fmt, MODULE_NAME, __func__, __LINE__, ##__VA_ARGS__) +#else +#define print_debug(fmt,...) +#endif +#define print_err(fmt,...) pr_err("%s:%s:%d: "fmt, MODULE_NAME, __func__,__LINE__, ##__VA_ARGS__) +#define print_info(fmt,...) pr_info("%s: "fmt, MODULE_NAME, ##__VA_ARGS__) + +/* ---------- GLOBALS ---------- */ +static struct cpufreq_driver bcm2835_cpufreq_driver; /* the cpufreq driver global */ +static unsigned int min_frequency, max_frequency; +static struct cpufreq_frequency_table bcm2835_freq_table[3]; + +/* + =============================================== + clk_rate either gets or sets the clock rates. + =============================================== +*/ + +static int bcm2835_cpufreq_clock_property(u32 tag, u32 id, u32 *val) +{ + struct rpi_firmware *fw = rpi_firmware_get(NULL); + struct { + u32 id; + u32 val; + } packet; + int ret; + + packet.id = id; + packet.val = *val; + ret = rpi_firmware_property(fw, tag, &packet, sizeof(packet)); + if (ret) + return ret; + + *val = packet.val; + + return 0; +} + +static uint32_t bcm2835_cpufreq_set_clock(int cur_rate, int arm_rate) +{ + u32 rate = arm_rate * 1000; + int ret; + + ret = bcm2835_cpufreq_clock_property(RPI_FIRMWARE_SET_CLOCK_RATE, VCMSG_ID_ARM_CLOCK, &rate); + if (ret) { + print_err("Failed to set clock: %d (%d)\n", arm_rate, ret); + return 0; + } + + rate /= 1000; + print_debug("Setting new frequency = %d -> %d (actual %d)\n", cur_rate, arm_rate, rate); + + return rate; +} + +static uint32_t bcm2835_cpufreq_get_clock(int tag) +{ + u32 rate; + int ret; + + ret = bcm2835_cpufreq_clock_property(tag, VCMSG_ID_ARM_CLOCK, &rate); + if (ret) { + print_err("Failed to get clock (%d)\n", ret); + return 0; + } + + rate /= 1000; + print_debug("%s frequency = %u\n", + tag == RPI_FIRMWARE_GET_CLOCK_RATE ? "Current": + tag == RPI_FIRMWARE_GET_MIN_CLOCK_RATE ? "Min": + tag == RPI_FIRMWARE_GET_MAX_CLOCK_RATE ? "Max": + "Unexpected", rate); + + return rate; +} + +/* + ==================================================== + Module Initialisation registers the cpufreq driver + ==================================================== +*/ +static int __init bcm2835_cpufreq_module_init(void) +{ + print_debug("IN\n"); + return cpufreq_register_driver(&bcm2835_cpufreq_driver); +} + +/* + ============= + Module exit + ============= +*/ +static void __exit bcm2835_cpufreq_module_exit(void) +{ + print_debug("IN\n"); + cpufreq_unregister_driver(&bcm2835_cpufreq_driver); + return; +} + +/* + ============================================================== + Initialisation function sets up the CPU policy for first use + ============================================================== +*/ +static int bcm2835_cpufreq_driver_init(struct cpufreq_policy *policy) +{ + /* measured value of how long it takes to change frequency */ + const unsigned int transition_latency = 355000; /* ns */ + + if (!rpi_firmware_get(NULL)) { + print_err("Firmware is not available\n"); + return -ENODEV; + } + + /* now find out what the maximum and minimum frequencies are */ + min_frequency = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE); + max_frequency = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_MAX_CLOCK_RATE); + + if (min_frequency == max_frequency) { + bcm2835_freq_table[0].frequency = min_frequency; + bcm2835_freq_table[1].frequency = CPUFREQ_TABLE_END; + } else { + bcm2835_freq_table[0].frequency = min_frequency; + bcm2835_freq_table[1].frequency = max_frequency; + bcm2835_freq_table[2].frequency = CPUFREQ_TABLE_END; + } + + print_info("min=%d max=%d\n", min_frequency, max_frequency); + return cpufreq_generic_init(policy, bcm2835_freq_table, transition_latency); +} + +/* + ===================================================================== + Target index function chooses the requested frequency from the table + ===================================================================== +*/ + +static int bcm2835_cpufreq_driver_target_index(struct cpufreq_policy *policy, unsigned int state) +{ + unsigned int target_freq = state == 0 ? min_frequency : max_frequency; + unsigned int cur = bcm2835_cpufreq_set_clock(policy->cur, target_freq); + + if (!cur) + { + print_err("Error occurred setting a new frequency (%d)\n", target_freq); + return -EINVAL; + } + print_debug("%s: %i: freq %d->%d\n", policy->governor->name, state, policy->cur, cur); + return 0; +} + +/* + ====================================================== + Get function returns the current frequency from table + ====================================================== +*/ + +static unsigned int bcm2835_cpufreq_driver_get(unsigned int cpu) +{ + unsigned int actual_rate = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_CLOCK_RATE); + print_debug("cpu%d: freq=%d\n", cpu, actual_rate); + return actual_rate <= min_frequency ? min_frequency : max_frequency; +} + +/* the CPUFreq driver */ +static struct cpufreq_driver bcm2835_cpufreq_driver = { + .name = "BCM2835 CPUFreq", + .init = bcm2835_cpufreq_driver_init, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = bcm2835_cpufreq_driver_target_index, + .get = bcm2835_cpufreq_driver_get, + .attr = cpufreq_generic_attr, +}; + +MODULE_AUTHOR("Dorian Peake and Dom Cobley"); +MODULE_DESCRIPTION("CPU frequency driver for BCM2835 chip"); +MODULE_LICENSE("GPL"); + +module_init(bcm2835_cpufreq_module_init); +module_exit(bcm2835_cpufreq_module_exit);