/*
* Copyright (C) 2011 Dmitry Eremin-Solenikov
* Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
* and Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This driver adds basic cpufreq support for SMU & 970FX based G5 Macs,
* that is iMac G5 and latest single CPU desktop.
*/
#undef DEBUG
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include <linux/time.h>
#include <linux/of_device.h>
#define DBG(fmt...) pr_debug(fmt)
/* see 970FX user manual */
#define SCOM_PCR 0x0aa001 /* PCR scom addr */
#define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */
#define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */
#define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */
#define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */
#define PCR_SPEED_MASK 0x000e0000U /* speed mask */
#define PCR_SPEED_SHIFT 17
#define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */
#define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */
#define PCR_TARGET_TIME_MASK 0x00006000U /* target time */
#define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */
#define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */
#define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */
#define SCOM_PSR 0x408001 /* PSR scom addr */
/* warning: PSR is a 64 bits register */
#define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */
#define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */
#define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */
#define PSR_CUR_SPEED_SHIFT (56)
/*
* The G5 only supports two frequencies (Quarter speed is not supported)
*/
#define CPUFREQ_HIGH 0
#define CPUFREQ_LOW 1
static struct cpufreq_frequency_table maple_cpu_freqs[] = {
{CPUFREQ_HIGH, 0},
{CPUFREQ_LOW, 0},
{0, CPUFREQ_TABLE_END},
};
/* Power mode data is an array of the 32 bits PCR values to use for
* the various frequencies, retrieved from the device-tree
*/
static int maple_pmode_cur;
static const u32 *maple_pmode_data;
static int maple_pmode_max;
/*
* SCOM based frequency switching for 970FX rev3
*/
static int maple_scom_switch_freq(int speed_mode)
{
unsigned long flags;
int to;
local_irq_save(flags);
/* Clear PCR high */
scom970_write(SCOM_PCR, 0);
/* Clear PCR low */
scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
/* Set PCR low */
scom970_write(SCOM_PCR, PCR_HILO_SELECT |
maple_pmode_data[speed_mode]);
/* Wait for completion */
for (to = 0; to < 10; to++) {
unsigned long psr = scom970_read(SCOM_PSR);
if ((psr & PSR_CMD_RECEIVED) == 0 &&
(((psr >> PSR_CUR_SPEED_SHIFT) ^
(maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
== 0)
break;
if (psr & PSR_CMD_COMPLETED)
break;
udelay(100);
}
local_irq_restore(flags);
maple_pmode_cur = speed_mode;
ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul;
return 0;
}
static int maple_scom_query_freq(void)
{
unsigned long psr = scom970_read(SCOM_PSR);
int i;
for (i = 0; i <= maple_pmode_max; i++)
if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
(maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
break;
return i;
}
/*
* Common interface to the cpufreq core
*/
static int maple_cpufreq_target(struct cpufreq_policy *policy,
unsigned int index)
{
return maple_scom_switch_freq(index);
}
static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
{
return maple_cpu_freqs[maple_pmode_cur].frequency;
}
static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
return cpufreq_generic_init(policy, maple_cpu_freqs, 12000);
}
static struct cpufreq_driver maple_cpufreq_driver = {
.name = "maple",
.flags = CPUFREQ_CONST_LOOPS,
.init = maple_cpufreq_cpu_init,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = maple_cpufreq_target,
.get = maple_cpufreq_get_speed,
.attr = cpufreq_generic_attr,
};
static int __init maple_cpufreq_init(void)
{
struct device_node *cpunode;
unsigned int psize;
unsigned long max_freq;
const u32 *valp;
u32 pvr_hi;
int rc = -ENODEV;
/*
* Behave here like powermac driver which checks machine compatibility
* to ease merging of two drivers in future.
*/
if (!of_machine_is_compatible("Momentum,Maple") &&
!of_machine_is_compatible("Momentum,Apache"))
return 0;
/* Get first CPU node */
cpunode = of_cpu_device_node_get(0);
if (cpunode == NULL) {
printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
goto bail_noprops;
}
/* Check 970FX for now */
/* we actually don't care on which CPU to access PVR */
pvr_hi = PVR_VER(mfspr(SPRN_PVR));
if (pvr_hi != 0x3c && pvr_hi != 0x44) {
printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n",
pvr_hi);
goto bail_noprops;
}
/* Look for the powertune data in the device-tree */
/*
* On Maple this property is provided by PIBS in dual-processor config,
* not provided by PIBS in CPU0 config and also not provided by SLOF,
* so YMMV
*/
maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
if (!maple_pmode_data) {
DBG("No power-mode-data !\n");
goto bail_noprops;
}
maple_pmode_max = psize / sizeof(u32) - 1;
/*
* From what I see, clock-frequency is always the maximal frequency.
* The current driver can not slew sysclk yet, so we really only deal
* with powertune steps for now. We also only implement full freq and
* half freq in this version. So far, I haven't yet seen a machine
* supporting anything else.
*/
valp = of_get_property(cpunode, "clock-frequency", NULL);
if (!valp)
return -ENODEV;
max_freq = (*valp)/1000;
maple_cpu_freqs[0].frequency = max_freq;
maple_cpu_freqs[1].frequency = max_freq/2;
/* Force apply current frequency to make sure everything is in
* sync (voltage is right for example). Firmware may leave us with
* a strange setting ...
*/
msleep(10);
maple_pmode_cur = -1;
maple_scom_switch_freq(maple_scom_query_freq());
printk(KERN_INFO "Registering Maple CPU frequency driver\n");
printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
maple_cpu_freqs[1].frequency/1000,
maple_cpu_freqs[0].frequency/1000,
maple_cpu_freqs[maple_pmode_cur].frequency/1000);
rc = cpufreq_register_driver(&maple_cpufreq_driver);
of_node_put(cpunode);
return rc;
bail_noprops:
of_node_put(cpunode);
return rc;
}
module_init(maple_cpufreq_init);
MODULE_LICENSE("GPL");
