From 4882beaf73302c162f08620d770f020211bf0acb Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Wed, 3 Jul 2013 00:49:20 +0100
Subject: [PATCH 14/54] Add cpufreq driver

---
 arch/arm/Kconfig                  |   1 +
 drivers/cpufreq/Kconfig.arm       |   8 ++
 drivers/cpufreq/Makefile          |   1 +
 drivers/cpufreq/bcm2835-cpufreq.c | 239 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100755 drivers/cpufreq/bcm2835-cpufreq.c

--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -389,6 +389,7 @@ config ARCH_BCM2708
 	select NEED_MACH_GPIO_H
 	select NEED_MACH_MEMORY_H
 	select CLKDEV_LOOKUP
+	select ARCH_HAS_CPUFREQ
 	select GENERIC_CLOCKEVENTS
 	select ARM_ERRATA_411920
 	select MACH_BCM2708
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -235,6 +235,14 @@ config ARM_SPEAR_CPUFREQ
 	help
 	  This adds the CPUFreq driver support for SPEAr SOCs.
 
+config ARM_BCM2835_CPUFREQ
+	bool "BCM2835 Driver"
+	default y
+	help
+	  This adds the CPUFreq driver for BCM2835
+
+	  If in doubt, say N.
+
 config ARM_TEGRA_CPUFREQ
 	bool "TEGRA CPUFreq support"
 	depends on ARCH_TEGRA
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_ARM_S5PV210_CPUFREQ)	+= s5p
 obj-$(CONFIG_ARM_SA1100_CPUFREQ)	+= sa1100-cpufreq.o
 obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
+obj-$(CONFIG_ARM_BCM2835_CPUFREQ)	+= bcm2835-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra-cpufreq.o
 obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
 
--- /dev/null
+++ b/drivers/cpufreq/bcm2835-cpufreq.c
@@ -0,0 +1,239 @@
+/*****************************************************************************
+* 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 */
+
+/*
+ ===============================================
+  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 */
+	policy->cpuinfo.transition_latency = 355000; /* ns */
+
+	/* now find out what the maximum and minimum frequencies are */
+	policy->min = policy->cpuinfo.min_freq = bcm2835_cpufreq_get_clock(VCMSG_GET_MIN_CLOCK);
+	policy->max = policy->cpuinfo.max_freq = bcm2835_cpufreq_get_clock(VCMSG_GET_MAX_CLOCK);
+	policy->cur = bcm2835_cpufreq_get_clock(VCMSG_GET_CLOCK_RATE);
+
+	print_info("min=%d max=%d cur=%d\n", policy->min, policy->max, policy->cur);
+	return 0;
+}
+
+/*
+ =================================================================================
+  Target function chooses the most appropriate frequency from the table to enable
+ =================================================================================
+*/
+
+static int bcm2835_cpufreq_driver_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation)
+{
+	unsigned int target = target_freq;
+#ifdef CPUFREQ_DEBUG_ENABLE
+	unsigned int cur = policy->cur;
+#endif
+	print_debug("%s: min=%d max=%d cur=%d target=%d\n",policy->governor->name,policy->min,policy->max,policy->cur,target_freq);
+
+	/* 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);
+
+	if (!policy->cur)
+	{
+		print_err("Error occurred setting a new frequency (%d)!\n", target);
+		policy->cur = bcm2835_cpufreq_get_clock(VCMSG_GET_CLOCK_RATE);
+		return -EINVAL;
+	}
+	print_debug("Freq %d->%d (min=%d max=%d target=%d request=%d)\n", cur, policy->cur, policy->min, policy->max, target_freq, target);
+	return 0;
+}
+
+static unsigned int bcm2835_cpufreq_driver_get(unsigned int cpu)
+{
+	unsigned int actual_rate = bcm2835_cpufreq_get_clock(VCMSG_GET_CLOCK_RATE);
+	print_debug("cpu=%d\n", actual_rate);
+	return actual_rate;
+}
+
+/*
+ =================================================================================
+  Verify ensures that when a policy is changed, it is suitable for the CPU to use
+ =================================================================================
+*/
+
+static int bcm2835_cpufreq_driver_verify(struct cpufreq_policy *policy)
+{
+	print_info("switching to governor %s\n", policy->governor->name);
+	return 0;
+}
+
+
+/* the CPUFreq driver */
+static struct cpufreq_driver bcm2835_cpufreq_driver = {
+		.name   = "BCM2835 CPUFreq",
+		.init   = bcm2835_cpufreq_driver_init,
+		.verify = bcm2835_cpufreq_driver_verify,
+		.target = bcm2835_cpufreq_driver_target,
+		.get    = bcm2835_cpufreq_driver_get
+};
+
+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);
