This adds a device tree binding for Broadcom BCM2834 CPU frequency control driven via Raspberry Pi VideoCore 4 firmware interface. Based on a driver by Dom Cobley. Signed-off-by: Dom Cobley <popcornmix@xxxxxxxxx> Signed-off-by: Lubomir Rintel <lkundrak@xxxxx> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx> Cc: Stephen Warren <swarren@xxxxxxxxxxxxx> Cc: Lee Jones <lee@xxxxxxxxxx> Cc: Eric Anholt <eric@xxxxxxxxxx> Cc: cpufreq@xxxxxxxxxxxxxxx Cc: linux-pm@xxxxxxxxxxxxxxx Cc: linux-rpi-kernel@xxxxxxxxxxxxxxxxxxx --- Depends on the RPi Firmware driver submitted on linux-rpi-kernel a while ago. Can't see it in arm-soc or linux-next yet though (?). Available in branch 'rpi-firmware' of https://github.com/anholt/linux arch/arm/boot/dts/bcm2835-rpi.dtsi | 5 + arch/arm/mach-bcm/Kconfig | 1 + drivers/cpufreq/Kconfig.arm | 9 ++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/bcm2835-cpufreq.c | 199 +++++++++++++++++++++++++++++++++++++ 5 files changed, 215 insertions(+) create mode 100644 drivers/cpufreq/bcm2835-cpufreq.c diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi b/arch/arm/boot/dts/bcm2835-rpi.dtsi index ab5474e..0895307 100644 --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi @@ -20,6 +20,11 @@ compatible = "raspberrypi,bcm2835-firmware"; mboxes = <&mailbox>; }; + + cpufreq { + compatible = "raspberrypi,bcm2835-cpufreq"; + firmware = <&firmware>; + }; }; }; diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig index 1319c3c..686f950 100644 --- a/arch/arm/mach-bcm/Kconfig +++ b/arch/arm/mach-bcm/Kconfig @@ -110,6 +110,7 @@ comment "Other Architectures" config ARCH_BCM2835 bool "Broadcom BCM2835 family" if ARCH_MULTI_V6 select ARCH_REQUIRE_GPIOLIB + select ARCH_HAS_CPUFREQ select ARM_AMBA select ARM_ERRATA_411920 select ARM_TIMER_SP804 diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm index cd0391e..2248373 100644 --- a/drivers/cpufreq/Kconfig.arm +++ b/drivers/cpufreq/Kconfig.arm @@ -227,3 +227,12 @@ config ARM_PXA2xx_CPUFREQ This add the CPUFreq driver support for Intel PXA2xx SOCs. If in doubt, say N. + +config ARM_BCM2835_CPUFREQ + tristate "Raspberry Pi BCM2835 CPUFreq support" + depends on RASPBERRYPI_FIRMWARE + help + This adds the BCM2835 CPU frequency control driver for Raspberry Pi + devices. + + If in doubt, say N. diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index 4134038..4543df9 100644 --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -52,6 +52,7 @@ obj-$(CONFIG_ARM_DT_BL_CPUFREQ) += arm_big_little_dt.o obj-$(CONFIG_ARCH_DAVINCI) += davinci-cpufreq.o obj-$(CONFIG_UX500_SOC_DB8500) += dbx500-cpufreq.o +obj-$(CONFIG_ARM_BCM2835_CPUFREQ) += bcm2835-cpufreq.o obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ) += exynos5440-cpufreq.o obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ) += highbank-cpufreq.o obj-$(CONFIG_ARM_HISI_ACPU_CPUFREQ) += hisi-acpu-cpufreq.o diff --git a/drivers/cpufreq/bcm2835-cpufreq.c b/drivers/cpufreq/bcm2835-cpufreq.c new file mode 100644 index 0000000..0fc4cb5 --- /dev/null +++ b/drivers/cpufreq/bcm2835-cpufreq.c @@ -0,0 +1,199 @@ +/* + * 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 appropriate 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. + * + * Copyright 2011 Broadcom Corporation. All rights reserved. + * Copyright 2013,2015 Lubomir Rintel + * + * Unless you and Broadcom execute a separate written software license + * agreement governing use of this software, this software is licensed to you + * under the terms of the GNU General Public License version 2, available at + * http://www.broadcom.com/licenses/GPLv2.php (the "GPL"). + * + * Notwithstanding the above, under no circumstances may you combine this + * software in any way with any other Broadcom software provided under a + * license other than the GPL, without Broadcom's express prior written + * consent. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/cpufreq.h> +#include <linux/dma-mapping.h> +#include <linux/mailbox_client.h> +#include <linux/platform_device.h> +#include <soc/bcm2835/raspberrypi-firmware.h> + +#define VCMSG_SET_CLOCK_RATE 0x00038002 +#define VCMSG_GET_CLOCK_RATE 0x00030002 +#define VCMSG_GET_MIN_CLOCK 0x00030007 +#define VCMSG_GET_MAX_CLOCK 0x00030004 +#define VCMSG_ID_ARM_CLOCK 0x00000003 /* Clock/Voltage ID's */ + +struct rpi_firmware *fw; + +/* tag part of the message */ +struct prop { + u32 dev_id; /* the ID of the clock/voltage to get or set */ + u32 val; /* the value (e.g. rate (in Hz)) to set */ +} __packed; + +static u32 bcm2835_cpufreq_set_clock(int cur_rate, int arm_rate) +{ + int ret = 0; + struct prop msg = { + .dev_id = VCMSG_ID_ARM_CLOCK, + .val = arm_rate * 1000, + }; + + /* send the message */ + ret = rpi_firmware_property(fw, VCMSG_SET_CLOCK_RATE, &msg, + sizeof(msg)); + + /* check if it was all ok and return the rate in KHz */ + if (ret) { + pr_err("bcm2835_cpufreq: could not set clock rate\n"); + return 0; + } + + return msg.val / 1000; +} + +static u32 bcm2835_cpufreq_get_clock(int tag) +{ + int ret = 0; + struct prop msg = { + .dev_id = VCMSG_ID_ARM_CLOCK, + .val = 0, + }; + + /* send the message */ + ret = rpi_firmware_property(fw, tag, &msg, sizeof(msg)); + + /* check if it was all ok and return the rate in KHz */ + if (ret) { + pr_err("bcm2835_cpufreq: could not get clock %d\n", tag); + return 0; + } + + return msg.val / 1000; +} + +static int bcm2835_cpufreq_init(struct cpufreq_policy *policy) +{ + /* measured value of how long it takes to change frequency */ + policy->cpuinfo.transition_latency = 355000; /* ns */ + + /* now find out what the maximum and minimum frequencies are */ + policy->min = bcm2835_cpufreq_get_clock(VCMSG_GET_MIN_CLOCK); + policy->max = bcm2835_cpufreq_get_clock(VCMSG_GET_MAX_CLOCK); + policy->cur = bcm2835_cpufreq_get_clock(VCMSG_GET_CLOCK_RATE); + + policy->cpuinfo.min_freq = policy->min; + policy->cpuinfo.max_freq = policy->max; + + return 0; +} + +static int bcm2835_cpufreq_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + unsigned int target = target_freq; + u32 cur; + + /* if we are above min and using ondemand, then just use max */ + if (strcmp("ondemand", policy->governor->name) == 0 && + target > policy->min) + target = policy->max; + + /* if the frequency is the same, just quit */ + if (target == policy->cur) + return 0; + + /* otherwise were good to set the clock frequency */ + policy->cur = bcm2835_cpufreq_set_clock(policy->cur, target); + + cur = bcm2835_cpufreq_set_clock(policy->cur, target); + if (!cur) + return -EINVAL; + + policy->cur = cur; + return 0; +} + +static unsigned int bcm2835_cpufreq_get(unsigned int cpu) +{ + return bcm2835_cpufreq_get_clock(VCMSG_GET_CLOCK_RATE); +} + +static int bcm2835_cpufreq_verify(struct cpufreq_policy *policy) +{ + return 0; +} + +static struct cpufreq_driver bcm2835_cpufreq = { + .name = "bcm2835-cpufreq", + .init = bcm2835_cpufreq_init, + .verify = bcm2835_cpufreq_verify, + .target = bcm2835_cpufreq_target, + .get = bcm2835_cpufreq_get +}; + +static int bcm2835_cpufreq_probe(struct platform_device *pdev) +{ + int ret; + struct device *dev = &pdev->dev; + struct device_node *fw_node; + + fw_node = of_parse_phandle(pdev->dev.of_node, "firmware", 0); + if (!fw_node) { + dev_err(dev, "no firmware node"); + return -ENODEV; + } + + fw = rpi_firmware_get(fw_node); + if (!fw) + return -EPROBE_DEFER; + + ret = cpufreq_register_driver(&bcm2835_cpufreq); + if (ret) { + dev_err(dev, "Could not register cpufreq driver\n"); + return ret; + } + + dev_info(dev, "Broadcom BCM2835 CPU frequency control\n"); + return 0; +} + +static int bcm2835_cpufreq_remove(struct platform_device *dev) +{ + cpufreq_unregister_driver(&bcm2835_cpufreq); + return 0; +} + +static const struct of_device_id bcm2835_cpufreq_of_match[] = { + { .compatible = "raspberrypi,bcm2835-cpufreq", }, + {}, +}; +MODULE_DEVICE_TABLE(of, bcm2835_cpufreq_of_match); + +static struct platform_driver bcm2835_cpufreq_driver = { + .probe = bcm2835_cpufreq_probe, + .remove = bcm2835_cpufreq_remove, + .driver = { + .name = "bcm2835-cpufreq", + .owner = THIS_MODULE, + .of_match_table = bcm2835_cpufreq_of_match, + }, +}; +module_platform_driver(bcm2835_cpufreq_driver); + +MODULE_AUTHOR("Dorian Peake and Dom Cobley and Lubomir Rintel"); +MODULE_DESCRIPTION("BCM2835 CPU frequency control driver"); +MODULE_LICENSE("GPL v2"); -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
