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