--- /dev/null
+/*
+ * 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 <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/cpufreq.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+/* ---------- 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);
projects / mirror_ubuntu-artful-kernel.git / commitdiff