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/*
* (C) Copyright 2008 Intel Corporation
* Authors:
* Andy Henroid <andrew.d.henroid@intel.com>
* Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
*/
/*
* Save DIMM power on Intel 7300-based platforms when all CPUs/cores
* are idle, using the DIMM thermal throttling capability.
*
* This driver depends on the Intel integrated DMA controller (I/O AT).
* If the driver for I/O AT (drivers/dma/ioatdma*) is also enabled,
* this driver should work cooperatively.
*/
/* #define DEBUG */
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/cpumask.h>
#include <linux/ktime.h>
#include <linux/delay.h>
#include <linux/debugfs.h>
#include <linux/stop_machine.h>
#include <linux/i7300_idle.h>
#include <asm/idle.h>
#include "../dma/ioat/hw.h"
#include "../dma/ioat/registers.h"
#define I7300_IDLE_DRIVER_VERSION "1.55"
#define I7300_PRINT "i7300_idle:"
#define MAX_STOP_RETRIES 10
static int debug;
module_param_named(debug, debug, uint, 0644);
MODULE_PARM_DESC(debug, "Enable debug printks in this driver");
static int forceload;
module_param_named(forceload, forceload, uint, 0644);
MODULE_PARM_DESC(debug, "Enable driver testing on unvalidated i5000");
#define dprintk(fmt, arg...) \
do { if (debug) printk(KERN_INFO I7300_PRINT fmt, ##arg); } while (0)
/*
* Value to set THRTLOW to when initiating throttling
* 0 = No throttling
* 1 = Throttle when > 4 activations per eval window (Maximum throttling)
* 2 = Throttle when > 8 activations
* 168 = Throttle when > 672 activations (Minimum throttling)
*/
#define MAX_THROTTLE_LOW_LIMIT 168
static uint throttle_low_limit = 1;
module_param_named(throttle_low_limit, throttle_low_limit, uint, 0644);
MODULE_PARM_DESC(throttle_low_limit,
"Value for THRTLOWLM activation field "
"(0 = disable throttle, 1 = Max throttle, 168 = Min throttle)");
/*
* simple invocation and duration statistics
*/
static unsigned long total_starts;
static unsigned long total_us;
#ifdef DEBUG
static unsigned long past_skip;
#endif
static struct pci_dev *fbd_dev;
static spinlock_t i7300_idle_lock;
static int i7300_idle_active;
static u8 i7300_idle_thrtctl_saved;
static u8 i7300_idle_thrtlow_saved;
static u32 i7300_idle_mc_saved;
static cpumask_var_t idle_cpumask;
static ktime_t start_ktime;
static unsigned long avg_idle_us;
static struct dentry *debugfs_dir;
/* Begin: I/O AT Helper routines */
#define IOAT_CHANBASE(ioat_ctl, chan) (ioat_ctl + 0x80 + 0x80 * chan)
/* Snoop control (disable snoops when coherency is not important) */
#define IOAT_DESC_SADDR_SNP_CTL (1UL << 1)
#define IOAT_DESC_DADDR_SNP_CTL (1UL << 2)
static struct pci_dev *ioat_dev;
static struct ioat_dma_descriptor *ioat_desc; /* I/O AT desc & data (1 page) */
static unsigned long ioat_desc_phys;
static u8 *ioat_iomap; /* I/O AT memory-mapped control regs (aka CB_BAR) */
static u8 *ioat_chanbase;
/* Start I/O AT memory copy */
static int i7300_idle_ioat_start(void)
{
u32 err;
/* Clear error (due to circular descriptor pointer) */
err = readl(ioat_chanbase + IOAT_CHANERR_OFFSET);
if (err)
writel(err, ioat_chanbase + IOAT_CHANERR_OFFSET);
writeb(IOAT_CHANCMD_START, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
return 0;
}
/* Stop I/O AT memory copy */
static void i7300_idle_ioat_stop(void)
{
int i;
u64 sts;
for (i = 0; i < MAX_STOP_RETRIES; i++) {
writeb(IOAT_CHANCMD_RESET,
ioat_chanbase + IOAT1_CHANCMD_OFFSET);
udelay(10);
sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_STATUS;
if (sts != IOAT_CHANSTS_ACTIVE)
break;
}
if (i == MAX_STOP_RETRIES) {
dprintk("failed to stop I/O AT after %d retries\n",
MAX_STOP_RETRIES);
}
}
/* Test I/O AT by copying 1024 byte from 2k to 1k */
static int __init i7300_idle_ioat_selftest(u8 *ctl,
struct ioat_dma_descriptor *desc, unsigned long desc_phys)
{
u64 chan_sts;
memset(desc, 0, 2048);
memset((u8 *) desc + 2048, 0xab, 1024);
desc[0].size = 1024;
desc[0].ctl = 0;
desc[0].src_addr = desc_phys + 2048;
desc[0].dst_addr = desc_phys + 1024;
desc[0].next = 0;
writeb(IOAT_CHANCMD_RESET, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
writeb(IOAT_CHANCMD_START, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
udelay(1000);
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_STATUS;
if (chan_sts != IOAT_CHANSTS_DONE) {
/* Not complete, reset the channel */
writeb(IOAT_CHANCMD_RESET,
ioat_chanbase + IOAT1_CHANCMD_OFFSET);
return -1;
}
if (*(u32 *) ((u8 *) desc + 3068) != 0xabababab ||
*(u32 *) ((u8 *) desc + 2044) != 0xabababab) {
dprintk("Data values src 0x%x, dest 0x%x, memset 0x%x\n",
*(u32 *) ((u8 *) desc + 2048),
*(u32 *) ((u8 *) desc + 1024),
*(u32 *) ((u8 *) desc + 3072));
return -1;
}
return 0;
}
static struct device dummy_dma_dev = {
.init_name = "fallback device",
.coherent_dma_mask = DMA_BIT_MASK(64),
.dma_mask = &dummy_dma_dev.coherent_dma_mask,
};
/* Setup and initialize I/O AT */
/* This driver needs I/O AT as the throttling takes effect only when there is
* some memory activity. We use I/O AT to set up a dummy copy, while all CPUs
* go idle and memory is throttled.
*/
static int __init i7300_idle_ioat_init(void)
{
u8 ver, chan_count, ioat_chan;
u16 chan_ctl;
ioat_iomap = (u8 *) ioremap_nocache(pci_resource_start(ioat_dev, 0),
pci_resource_len(ioat_dev, 0));
if (!ioat_iomap) {
printk(KERN_ERR I7300_PRINT "failed to map I/O AT registers\n");
goto err_ret;
}
ver = readb(ioat_iomap + IOAT_VER_OFFSET);
if (ver != IOAT_VER_1_2) {
printk(KERN_ERR I7300_PRINT "unknown I/O AT version (%u.%u)\n",
ver >> 4, ver & 0xf);
goto err_unmap;
}
chan_count = readb(ioat_iomap + IOAT_CHANCNT_OFFSET);
if (!chan_count) {
printk(KERN_ERR I7300_PRINT "unexpected # of I/O AT channels "
"(%u)\n",
chan_count);
goto err_unmap;
}
ioat_chan = chan_count - 1;
ioat_chanbase = IOAT_CHANBASE(ioat_iomap, ioat_chan);
chan_ctl = readw(ioat_chanbase + IOAT_CHANCTRL_OFFSET);
if (chan_ctl & IOAT_CHANCTRL_CHANNEL_IN_USE) {
printk(KERN_ERR I7300_PRINT "channel %d in use\n", ioat_chan);
goto err_unmap;
}
writew(IOAT_CHANCTRL_CHANNEL_IN_USE,
ioat_chanbase + IOAT_CHANCTRL_OFFSET);
ioat_desc = (struct ioat_dma_descriptor *)dma_alloc_coherent(
&dummy_dma_dev, 4096,
(dma_addr_t *)&ioat_desc_phys, GFP_KERNEL);
if (!ioat_desc) {
printk(KERN_ERR I7300_PRINT "failed to allocate I/O AT desc\n");
goto err_mark_unused;
}
writel(ioat_desc_phys & 0xffffffffUL,
ioat_chanbase + IOAT1_CHAINADDR_OFFSET_LOW);
writel(ioat_desc_phys >> 32,
ioat_chanbase + IOAT1_CHAINADDR_OFFSET_HIGH);
if (i7300_idle_ioat_selftest(ioat_iomap, ioat_desc, ioat_desc_phys)) {
printk(KERN_ERR I7300_PRINT "I/O AT self-test failed\n");
goto err_free;
}
/* Setup circular I/O AT descriptor chain */
ioat_desc[0].ctl = IOAT_DESC_SADDR_SNP_CTL | IOAT_DESC_DADDR_SNP_CTL;
ioat_desc[0].src_addr = ioat_desc_phys + 2048;
ioat_desc[0].dst_addr = ioat_desc_phys + 3072;
ioat_desc[0].size = 128;
ioat_desc[0].next = ioat_desc_phys + sizeof(struct ioat_dma_descriptor);
ioat_desc[1].ctl = ioat_desc[0].ctl;
ioat_desc[1].src_addr = ioat_desc[0].src_addr;
ioat_desc[1].dst_addr = ioat_desc[0].dst_addr;
ioat_desc[1].size = ioat_desc[0].size;
ioat_desc[1].next = ioat_desc_phys;
return 0;
err_free:
dma_free_coherent(&dummy_dma_dev, 4096, (void *)ioat_desc, 0);
err_mark_unused:
writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
err_unmap:
iounmap(ioat_iomap);
err_ret:
return -ENODEV;
}
/* Cleanup I/O AT */
static void __exit i7300_idle_ioat_exit(void)
{
int i;
u64 chan_sts;
i7300_idle_ioat_stop();
/* Wait for a while for the channel to halt before releasing */
for (i = 0; i < MAX_STOP_RETRIES; i++) {
writeb(IOAT_CHANCMD_RESET,
ioat_chanbase + IOAT1_CHANCMD_OFFSET);
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_STATUS;
if (chan_sts != IOAT_CHANSTS_ACTIVE) {
writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
break;
}
udelay(1000);
}
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_STATUS;
/*
* We tried to reset multiple times. If IO A/T channel is still active
* flag an error and return without cleanup. Memory leak is better
* than random corruption in that extreme error situation.
*/
if (chan_sts == IOAT_CHANSTS_ACTIVE) {
printk(KERN_ERR I7300_PRINT "Unable to stop IO A/T channels."
" Not freeing resources\n");
return;
}
dma_free_coherent(&dummy_dma_dev, 4096, (void *)ioat_desc, 0);
iounmap(ioat_iomap);
}
/* End: I/O AT Helper routines */
#define DIMM_THRTLOW 0x64
#define DIMM_THRTCTL 0x67
#define DIMM_THRTCTL_THRMHUNT (1UL << 0)
#define DIMM_MC 0x40
#define DIMM_GTW_MODE (1UL << 17)
#define DIMM_GBLACT 0x60
/*
* Keep track of an exponential-decaying average of recent idle durations.
* The latest duration gets DURATION_WEIGHT_PCT percentage weight
* in this average, with the old average getting the remaining weight.
*
* High weights emphasize recent history, low weights include long history.
*/
#define DURATION_WEIGHT_PCT 55
/*
* When the decaying average of recent durations or the predicted duration
* of the next timer interrupt is shorter than duration_threshold, the
* driver will decline to throttle.
*/
#define DURATION_THRESHOLD_US 100
/* Store DIMM thermal throttle configuration */
static int i7300_idle_thrt_save(void)
{
u32 new_mc_val;
u8 gblactlm;
pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &i7300_idle_thrtctl_saved);
pci_read_config_byte(fbd_dev, DIMM_THRTLOW, &i7300_idle_thrtlow_saved);
pci_read_config_dword(fbd_dev, DIMM_MC, &i7300_idle_mc_saved);
/*
* Make sure we have Global Throttling Window Mode set to have a
* "short" window. This (mostly) works around an issue where
* throttling persists until the end of the global throttling window
* size. On the tested system, this was resulting in a maximum of
* 64 ms to exit throttling (average 32 ms). The actual numbers
* depends on system frequencies. Setting the short window reduces
* this by a factor of 4096.
*
* We will only do this only if the system is set for
* unlimited-activations while in open-loop throttling (i.e., when
* Global Activation Throttle Limit is zero).
*/
pci_read_config_byte(fbd_dev, DIMM_GBLACT, &gblactlm);
dprintk("thrtctl_saved = 0x%02x, thrtlow_saved = 0x%02x\n",
i7300_idle_thrtctl_saved,
i7300_idle_thrtlow_saved);
dprintk("mc_saved = 0x%08x, gblactlm = 0x%02x\n",
i7300_idle_mc_saved,
gblactlm);
if (gblactlm == 0) {
new_mc_val = i7300_idle_mc_saved | DIMM_GTW_MODE;
pci_write_config_dword(fbd_dev, DIMM_MC, new_mc_val);
return 0;
} else {
dprintk("could not set GTW_MODE = 1 (OLTT enabled)\n");
return -ENODEV;
}
}
/* Restore DIMM thermal throttle configuration */
static void i7300_idle_thrt_restore(void)
{
pci_write_config_dword(fbd_dev, DIMM_MC, i7300_idle_mc_saved);
pci_write_config_byte(fbd_dev, DIMM_THRTLOW, i7300_idle_thrtlow_saved);
pci_write_config_byte(fbd_dev, DIMM_THRTCTL, i7300_idle_thrtctl_saved);
}
/* Enable DIMM thermal throttling */
static void i7300_idle_start(void)
{
u8 new_ctl;
u8 limit;
new_ctl = i7300_idle_thrtctl_saved & ~DIMM_THRTCTL_THRMHUNT;
pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
limit = throttle_low_limit;
if (unlikely(limit > MAX_THROTTLE_LOW_LIMIT))
limit = MAX_THROTTLE_LOW_LIMIT;
pci_write_config_byte(fbd_dev, DIMM_THRTLOW, limit);
new_ctl = i7300_idle_thrtctl_saved | DIMM_THRTCTL_THRMHUNT;
pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
}
/* Disable DIMM thermal throttling */
static void i7300_idle_stop(void)
{
u8 new_ctl;
u8 got_ctl;
new_ctl = i7300_idle_thrtctl_saved & ~DIMM_THRTCTL_THRMHUNT;
pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl);
pci_write_config_byte(fbd_dev, DIMM_THRTLOW, i7300_idle_thrtlow_saved);
pci_write_config_byte(fbd_dev, DIMM_THRTCTL, i7300_idle_thrtctl_saved);
pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &got_ctl);
WARN_ON_ONCE(got_ctl != i7300_idle_thrtctl_saved);
}
/*
* i7300_avg_duration_check()
* return 0 if the decaying average of recent idle durations is
* more than DURATION_THRESHOLD_US
*/
static int i7300_avg_duration_check(void)
{
if (avg_idle_us >= DURATION_THRESHOLD_US)
return 0;
#ifdef DEBUG
past_skip++;
#endif
return 1;
}
/* Idle notifier to look at idle CPUs */
static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
unsigned long flags;
ktime_t now_ktime;
static ktime_t idle_begin_time;
static int time_init = 1;
if (!throttle_low_limit)
return 0;
if (unlikely(time_init)) {
time_init = 0;
idle_begin_time = ktime_get();
}
spin_lock_irqsave(&i7300_idle_lock, flags);
if (val == IDLE_START) {
cpumask_set_cpu(smp_processor_id(), idle_cpumask);
if (cpumask_weight(idle_cpumask) != num_online_cpus())
goto end;
now_ktime = ktime_get();
idle_begin_time = now_ktime;
if (i7300_avg_duration_check())
goto end;
i7300_idle_active = 1;
total_starts++;
start_ktime = now_ktime;
i7300_idle_start();
i7300_idle_ioat_start();
} else if (val == IDLE_END) {
cpumask_clear_cpu(smp_processor_id(), idle_cpumask);
if (cpumask_weight(idle_cpumask) == (num_online_cpus() - 1)) {
/* First CPU coming out of idle */
u64 idle_duration_us;
now_ktime = ktime_get();
idle_duration_us = ktime_to_us(ktime_sub
(now_ktime, idle_begin_time));
avg_idle_us =
((100 - DURATION_WEIGHT_PCT) * avg_idle_us +
DURATION_WEIGHT_PCT * idle_duration_us) / 100;
if (i7300_idle_active) {
ktime_t idle_ktime;
idle_ktime = ktime_sub(now_ktime, start_ktime);
total_us += ktime_to_us(idle_ktime);
i7300_idle_ioat_stop();
i7300_idle_stop();
i7300_idle_active = 0;
}
}
}
end:
spin_unlock_irqrestore(&i7300_idle_lock, flags);
return 0;
}
static struct notifier_block i7300_idle_nb = {
.notifier_call = i7300_idle_notifier,
};
MODULE_DEVICE_TABLE(pci, pci_tbl);
int stats_open_generic(struct inode *inode, struct file *fp)
{
fp->private_data = inode->i_private;
return 0;
}
static ssize_t stats_read_ul(struct file *fp, char __user *ubuf, size_t count,
loff_t *off)
{
unsigned long *p = fp->private_data;
char buf[32];
int len;
len = snprintf(buf, 32, "%lu\n", *p);
return simple_read_from_buffer(ubuf, count, off, buf, len);
}
static const struct file_operations idle_fops = {
.open = stats_open_generic,
.read = stats_read_ul,
.llseek = default_llseek,
};
struct debugfs_file_info {
void *ptr;
char name[32];
struct dentry *file;
} debugfs_file_list[] = {
{&total_starts, "total_starts", NULL},
{&total_us, "total_us", NULL},
#ifdef DEBUG
{&past_skip, "past_skip", NULL},
#endif
{NULL, "", NULL}
};
static int __init i7300_idle_init(void)
{
spin_lock_init(&i7300_idle_lock);
total_us = 0;
if (i7300_idle_platform_probe(&fbd_dev, &ioat_dev, forceload))
return -ENODEV;
if (i7300_idle_thrt_save())
return -ENODEV;
if (i7300_idle_ioat_init())
return -ENODEV;
if (!zalloc_cpumask_var(&idle_cpumask, GFP_KERNEL))
return -ENOMEM;
debugfs_dir = debugfs_create_dir("i7300_idle", NULL);
if (debugfs_dir) {
int i = 0;
while (debugfs_file_list[i].ptr != NULL) {
debugfs_file_list[i].file = debugfs_create_file(
debugfs_file_list[i].name,
S_IRUSR,
debugfs_dir,
debugfs_file_list[i].ptr,
&idle_fops);
i++;
}
}
idle_notifier_register(&i7300_idle_nb);
printk(KERN_INFO "i7300_idle: loaded v%s\n", I7300_IDLE_DRIVER_VERSION);
return 0;
}
static void __exit i7300_idle_exit(void)
{
idle_notifier_unregister(&i7300_idle_nb);
free_cpumask_var(idle_cpumask);
if (debugfs_dir) {
int i = 0;
while (debugfs_file_list[i].file != NULL) {
debugfs_remove(debugfs_file_list[i].file);
i++;
}
debugfs_remove(debugfs_dir);
}
i7300_idle_thrt_restore();
i7300_idle_ioat_exit();
}
module_init(i7300_idle_init);
module_exit(i7300_idle_exit);
MODULE_AUTHOR("Andy Henroid <andrew.d.henroid@intel.com>");
MODULE_DESCRIPTION("Intel Chipset DIMM Idle Power Saving Driver v"
I7300_IDLE_DRIVER_VERSION);
MODULE_LICENSE("GPL");