[mirror_ubuntu-artful-kernel.git] / drivers / cpufreq / bcm2835-cpufreq.c

/*
 * 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);
Commit	Line	Data
723cd625	1	/*
	2	* Copyright 2011 Broadcom Corporation.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* as published by the Free Software Foundation; version 2
	7	* of the License.
	8	*
	9	* This driver dynamically manages the CPU Frequency of the ARM
	10	* processor. Messages are sent to Videocore either setting or requesting the
	11	* frequency of the ARM in order to match an appropiate frequency to the current
	12	* usage of the processor. The policy which selects the frequency to use is
	13	* defined in the kernel .config file, but can be changed during runtime.
	14	*/
	15
	16	/* ---------- INCLUDES ---------- */
	17	#include <linux/kernel.h>
	18	#include <linux/init.h>
	19	#include <linux/module.h>
	20	#include <linux/cpufreq.h>
	21	#include <soc/bcm2835/raspberrypi-firmware.h>
	22
	23	/* ---------- DEFINES ---------- */
	24	/#define CPUFREQ_DEBUG_ENABLE/ /* enable debugging */
	25	#define MODULE_NAME "bcm2835-cpufreq"
	26
	27	#define VCMSG_ID_ARM_CLOCK 0x000000003 /* Clock/Voltage ID's */
	28
	29	/* debug printk macros */
	30	#ifdef CPUFREQ_DEBUG_ENABLE
	31	#define print_debug(fmt,...) pr_debug("%s:%s:%d: "fmt, MODULE_NAME, __func__, __LINE__, ##__VA_ARGS__)
	32	#else
	33	#define print_debug(fmt,...)
	34	#endif
	35	#define print_err(fmt,...) pr_err("%s:%s:%d: "fmt, MODULE_NAME, __func__,__LINE__, ##__VA_ARGS__)
	36	#define print_info(fmt,...) pr_info("%s: "fmt, MODULE_NAME, ##__VA_ARGS__)
	37
	38	/* ---------- GLOBALS ---------- */
	39	static struct cpufreq_driver bcm2835_cpufreq_driver; /* the cpufreq driver global */
	40	static unsigned int min_frequency, max_frequency;
	41	static struct cpufreq_frequency_table bcm2835_freq_table[3];
	42
	43	/*
	44	===============================================
	45	clk_rate either gets or sets the clock rates.
	46	===============================================
	47	*/
	48
	49	static int bcm2835_cpufreq_clock_property(u32 tag, u32 id, u32 *val)
	50	{
	51	struct rpi_firmware *fw = rpi_firmware_get(NULL);
	52	struct {
	53	u32 id;
	54	u32 val;
	55	} packet;
	56	int ret;
	57
	58	packet.id = id;
	59	packet.val = *val;
	60	ret = rpi_firmware_property(fw, tag, &packet, sizeof(packet));
	61	if (ret)
	62	return ret;
	63
	64	*val = packet.val;
65
66	return 0;
67	}
68
69	static uint32_t bcm2835_cpufreq_set_clock(int cur_rate, int arm_rate)
70	{
71	u32 rate = arm_rate * 1000;
72	int ret;
73
74	ret = bcm2835_cpufreq_clock_property(RPI_FIRMWARE_SET_CLOCK_RATE, VCMSG_ID_ARM_CLOCK, &rate);
75	if (ret) {
76	print_err("Failed to set clock: %d (%d)\n", arm_rate, ret);
77	return 0;
78	}
79
80	rate /= 1000;
81	print_debug("Setting new frequency = %d -> %d (actual %d)\n", cur_rate, arm_rate, rate);
82
83	return rate;
84	}
85
86	static uint32_t bcm2835_cpufreq_get_clock(int tag)
87	{
88	u32 rate;
89	int ret;
90
91	ret = bcm2835_cpufreq_clock_property(tag, VCMSG_ID_ARM_CLOCK, &rate);
92	if (ret) {
93	print_err("Failed to get clock (%d)\n", ret);
94	return 0;
95	}
96
97	rate /= 1000;
98	print_debug("%s frequency = %u\n",
99	tag == RPI_FIRMWARE_GET_CLOCK_RATE ? "Current":
100	tag == RPI_FIRMWARE_GET_MIN_CLOCK_RATE ? "Min":
101	tag == RPI_FIRMWARE_GET_MAX_CLOCK_RATE ? "Max":
102	"Unexpected", rate);
103
104	return rate;
105	}
106
107	/*
108	====================================================
109	Module Initialisation registers the cpufreq driver
110	====================================================
111	*/
112	static int __init bcm2835_cpufreq_module_init(void)
113	{
114	print_debug("IN\n");
115	return cpufreq_register_driver(&bcm2835_cpufreq_driver);
116	}
117
118	/*
119	=============
120	Module exit
121	=============
122	*/
123	static void __exit bcm2835_cpufreq_module_exit(void)
124	{
125	print_debug("IN\n");
126	cpufreq_unregister_driver(&bcm2835_cpufreq_driver);
127	return;
128	}
129
130	/*
131	==============================================================
132	Initialisation function sets up the CPU policy for first use
133	==============================================================
134	*/
135	static int bcm2835_cpufreq_driver_init(struct cpufreq_policy *policy)
136	{
137	/* measured value of how long it takes to change frequency */
138	const unsigned int transition_latency = 355000; /* ns */
139
140	if (!rpi_firmware_get(NULL)) {
141	print_err("Firmware is not available\n");
142	return -ENODEV;
143	}
144
145	/* now find out what the maximum and minimum frequencies are */
146	min_frequency = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
147	max_frequency = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_MAX_CLOCK_RATE);
148
149	if (min_frequency == max_frequency) {
150	bcm2835_freq_table[0].frequency = min_frequency;
151	bcm2835_freq_table[1].frequency = CPUFREQ_TABLE_END;
152	} else {
153	bcm2835_freq_table[0].frequency = min_frequency;
154	bcm2835_freq_table[1].frequency = max_frequency;
155	bcm2835_freq_table[2].frequency = CPUFREQ_TABLE_END;
156	}
157
158	print_info("min=%d max=%d\n", min_frequency, max_frequency);
159	return cpufreq_generic_init(policy, bcm2835_freq_table, transition_latency);
160	}
161
162	/*
163	=====================================================================
164	Target index function chooses the requested frequency from the table
165	=====================================================================
166	*/
167
168	static int bcm2835_cpufreq_driver_target_index(struct cpufreq_policy *policy, unsigned int state)
169	{
170	unsigned int target_freq = state == 0 ? min_frequency : max_frequency;
171	unsigned int cur = bcm2835_cpufreq_set_clock(policy->cur, target_freq);
172
173	if (!cur)
174	{
175	print_err("Error occurred setting a new frequency (%d)\n", target_freq);
176	return -EINVAL;
177	}
178	print_debug("%s: %i: freq %d->%d\n", policy->governor->name, state, policy->cur, cur);
179	return 0;
180	}
181
182	/*
183	======================================================
184	Get function returns the current frequency from table
185	======================================================
186	*/
187
188	static unsigned int bcm2835_cpufreq_driver_get(unsigned int cpu)
189	{
190	unsigned int actual_rate = bcm2835_cpufreq_get_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
191	print_debug("cpu%d: freq=%d\n", cpu, actual_rate);
192	return actual_rate <= min_frequency ? min_frequency : max_frequency;
193	}
194
195	/* the CPUFreq driver */
196	static struct cpufreq_driver bcm2835_cpufreq_driver = {
197	.name = "BCM2835 CPUFreq",
198	.init = bcm2835_cpufreq_driver_init,
199	.verify = cpufreq_generic_frequency_table_verify,
200	.target_index = bcm2835_cpufreq_driver_target_index,
201	.get = bcm2835_cpufreq_driver_get,
202	.attr = cpufreq_generic_attr,
203	};
204
205	MODULE_AUTHOR("Dorian Peake and Dom Cobley");
206	MODULE_DESCRIPTION("CPU frequency driver for BCM2835 chip");
207	MODULE_LICENSE("GPL");
208
209	module_init(bcm2835_cpufreq_module_init);
210	module_exit(bcm2835_cpufreq_module_exit);