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authorpopcornmix <popcornmix@gmail.com>2013-07-03 00:49:20 +0100
committerpopcornmix <popcornmix@gmail.com>2015-05-18 14:10:31 +0100
commit0ab0bffea9f10d7ed1c5e886452f14a7daa0a423 (patch)
tree8493177eea0aeb738cfb26a523837fa2e4da71e0 /drivers/cpufreq/bcm2835-cpufreq.c
parente67cc0738c17eaf89e5ed400a5ff0ecdb9381558 (diff)
downloadlinux-0ab0bffea9f10d7ed1c5e886452f14a7daa0a423.tar.gz
Add cpufreq driver
Diffstat (limited to 'drivers/cpufreq/bcm2835-cpufreq.c')
-rwxr-xr-xdrivers/cpufreq/bcm2835-cpufreq.c224
1 files changed, 224 insertions, 0 deletions
diff --git a/drivers/cpufreq/bcm2835-cpufreq.c b/drivers/cpufreq/bcm2835-cpufreq.c
new file mode 100755
index 000000000000..447ca0902704
--- /dev/null
+++ b/drivers/cpufreq/bcm2835-cpufreq.c
@@ -0,0 +1,224 @@
+/*****************************************************************************
+* Copyright 2011 Broadcom Corporation. All rights reserved.
+*
+* 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.
+*****************************************************************************/
+
+/*****************************************************************************
+* FILENAME: bcm2835-cpufreq.h
+* DESCRIPTION: 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 <mach/vcio.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__)
+
+/* tag part of the message */
+struct vc_msg_tag {
+ uint32_t tag_id; /* the message id */
+ uint32_t buffer_size; /* size of the buffer (which in this case is always 8 bytes) */
+ uint32_t data_size; /* amount of data being sent or received */
+ uint32_t dev_id; /* the ID of the clock/voltage to get or set */
+ uint32_t val; /* the value (e.g. rate (in Hz)) to set */
+};
+
+/* message structure to be sent to videocore */
+struct vc_msg {
+ uint32_t msg_size; /* simply, sizeof(struct vc_msg) */
+ uint32_t request_code; /* holds various information like the success and number of bytes returned (refer to mailboxes wiki) */
+ struct vc_msg_tag tag; /* the tag structure above to make */
+ uint32_t end_tag; /* an end identifier, should be set to NULL */
+};
+
+/* ---------- GLOBALS ---------- */
+static struct cpufreq_driver bcm2835_cpufreq_driver; /* the cpufreq driver global */
+
+static struct cpufreq_frequency_table bcm2835_freq_table[] = {
+ {0, 0, 0},
+ {0, 0, 0},
+ {0, 0, CPUFREQ_TABLE_END},
+};
+
+/*
+ ===============================================
+ clk_rate either gets or sets the clock rates.
+ ===============================================
+*/
+static uint32_t bcm2835_cpufreq_set_clock(int cur_rate, int arm_rate)
+{
+ int s, actual_rate=0;
+ struct vc_msg msg;
+
+ /* wipe all previous message data */
+ memset(&msg, 0, sizeof msg);
+
+ msg.msg_size = sizeof msg;
+
+ msg.tag.tag_id = VCMSG_SET_CLOCK_RATE;
+ msg.tag.buffer_size = 8;
+ msg.tag.data_size = 8; /* we're sending the clock ID and the new rates which is a total of 2 words */
+ msg.tag.dev_id = VCMSG_ID_ARM_CLOCK;
+ msg.tag.val = arm_rate * 1000;
+
+ /* send the message */
+ s = bcm_mailbox_property(&msg, sizeof msg);
+
+ /* check if it was all ok and return the rate in KHz */
+ if (s == 0 && (msg.request_code & 0x80000000))
+ actual_rate = msg.tag.val/1000;
+
+ print_debug("Setting new frequency = %d -> %d (actual %d)\n", cur_rate, arm_rate, actual_rate);
+ return actual_rate;
+}
+
+static uint32_t bcm2835_cpufreq_get_clock(int tag)
+{
+ int s;
+ int arm_rate = 0;
+ struct vc_msg msg;
+
+ /* wipe all previous message data */
+ memset(&msg, 0, sizeof msg);
+
+ msg.msg_size = sizeof msg;
+ msg.tag.tag_id = tag;
+ msg.tag.buffer_size = 8;
+ msg.tag.data_size = 4; /* we're just sending the clock ID which is one word long */
+ msg.tag.dev_id = VCMSG_ID_ARM_CLOCK;
+
+ /* send the message */
+ s = bcm_mailbox_property(&msg, sizeof msg);
+
+ /* check if it was all ok and return the rate in KHz */
+ if (s == 0 && (msg.request_code & 0x80000000))
+ arm_rate = msg.tag.val/1000;
+
+ print_debug("%s frequency = %d\n",
+ tag == VCMSG_GET_CLOCK_RATE ? "Current":
+ tag == VCMSG_GET_MIN_CLOCK ? "Min":
+ tag == VCMSG_GET_MAX_CLOCK ? "Max":
+ "Unexpected", arm_rate);
+
+ return arm_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 */
+
+ /* now find out what the maximum and minimum frequencies are */
+ bcm2835_freq_table[0].frequency = bcm2835_cpufreq_get_clock(VCMSG_GET_MIN_CLOCK);
+ bcm2835_freq_table[1].frequency = bcm2835_cpufreq_get_clock(VCMSG_GET_MAX_CLOCK);
+
+ print_info("min=%d max=%d\n", bcm2835_freq_table[0].frequency, bcm2835_freq_table[1].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 = bcm2835_freq_table[state].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(VCMSG_GET_CLOCK_RATE);
+ print_debug("%d: freq=%d\n", cpu, actual_rate);
+ return actual_rate <= bcm2835_freq_table[0].frequency ? bcm2835_freq_table[0].frequency : bcm2835_freq_table[1].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);