--- /dev/null
+/*
+ * (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 raw_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();
+ }
+
+ raw_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:
+ raw_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);
+
+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 = simple_open,
+ .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)
+{
+ raw_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");
Code Review / kvmfornfv.git / blobdiff