linux/drivers/memory/tegra/tegra20-emc.c
Dmitry Osipenko adbcec8862 memory: tegra20-emc: Poll EMC-CaR handshake instead of waiting for interrupt
The memory clock-rate change could be running on a non-boot CPU, while the
boot CPU handles the EMC interrupt. This introduces an unnecessary latency
since boot CPU should handle the interrupt and then notify the sibling CPU
about clock-rate change completion. In some rare cases boot CPU could be
in uninterruptible state for a significant time (like in a case of KASAN +
NFS root), it could get to the point that completion timeouts before boot
CPU gets a chance to handle interrupt. The solution is to get rid of the
completion and replace it with interrupt-status polling.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
2020-06-22 13:54:57 +02:00

754 lines
17 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Tegra20 External Memory Controller driver
*
* Author: Dmitry Osipenko <digetx@gmail.com>
*/
#include <linux/clk.h>
#include <linux/clk/tegra.h>
#include <linux/debugfs.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/sort.h>
#include <linux/types.h>
#include <soc/tegra/fuse.h>
#define EMC_INTSTATUS 0x000
#define EMC_INTMASK 0x004
#define EMC_DBG 0x008
#define EMC_TIMING_CONTROL 0x028
#define EMC_RC 0x02c
#define EMC_RFC 0x030
#define EMC_RAS 0x034
#define EMC_RP 0x038
#define EMC_R2W 0x03c
#define EMC_W2R 0x040
#define EMC_R2P 0x044
#define EMC_W2P 0x048
#define EMC_RD_RCD 0x04c
#define EMC_WR_RCD 0x050
#define EMC_RRD 0x054
#define EMC_REXT 0x058
#define EMC_WDV 0x05c
#define EMC_QUSE 0x060
#define EMC_QRST 0x064
#define EMC_QSAFE 0x068
#define EMC_RDV 0x06c
#define EMC_REFRESH 0x070
#define EMC_BURST_REFRESH_NUM 0x074
#define EMC_PDEX2WR 0x078
#define EMC_PDEX2RD 0x07c
#define EMC_PCHG2PDEN 0x080
#define EMC_ACT2PDEN 0x084
#define EMC_AR2PDEN 0x088
#define EMC_RW2PDEN 0x08c
#define EMC_TXSR 0x090
#define EMC_TCKE 0x094
#define EMC_TFAW 0x098
#define EMC_TRPAB 0x09c
#define EMC_TCLKSTABLE 0x0a0
#define EMC_TCLKSTOP 0x0a4
#define EMC_TREFBW 0x0a8
#define EMC_QUSE_EXTRA 0x0ac
#define EMC_ODT_WRITE 0x0b0
#define EMC_ODT_READ 0x0b4
#define EMC_FBIO_CFG5 0x104
#define EMC_FBIO_CFG6 0x114
#define EMC_AUTO_CAL_INTERVAL 0x2a8
#define EMC_CFG_2 0x2b8
#define EMC_CFG_DIG_DLL 0x2bc
#define EMC_DLL_XFORM_DQS 0x2c0
#define EMC_DLL_XFORM_QUSE 0x2c4
#define EMC_ZCAL_REF_CNT 0x2e0
#define EMC_ZCAL_WAIT_CNT 0x2e4
#define EMC_CFG_CLKTRIM_0 0x2d0
#define EMC_CFG_CLKTRIM_1 0x2d4
#define EMC_CFG_CLKTRIM_2 0x2d8
#define EMC_CLKCHANGE_REQ_ENABLE BIT(0)
#define EMC_CLKCHANGE_PD_ENABLE BIT(1)
#define EMC_CLKCHANGE_SR_ENABLE BIT(2)
#define EMC_TIMING_UPDATE BIT(0)
#define EMC_REFRESH_OVERFLOW_INT BIT(3)
#define EMC_CLKCHANGE_COMPLETE_INT BIT(4)
#define EMC_DBG_READ_MUX_ASSEMBLY BIT(0)
#define EMC_DBG_WRITE_MUX_ACTIVE BIT(1)
#define EMC_DBG_FORCE_UPDATE BIT(2)
#define EMC_DBG_READ_DQM_CTRL BIT(9)
#define EMC_DBG_CFG_PRIORITY BIT(24)
static const u16 emc_timing_registers[] = {
EMC_RC,
EMC_RFC,
EMC_RAS,
EMC_RP,
EMC_R2W,
EMC_W2R,
EMC_R2P,
EMC_W2P,
EMC_RD_RCD,
EMC_WR_RCD,
EMC_RRD,
EMC_REXT,
EMC_WDV,
EMC_QUSE,
EMC_QRST,
EMC_QSAFE,
EMC_RDV,
EMC_REFRESH,
EMC_BURST_REFRESH_NUM,
EMC_PDEX2WR,
EMC_PDEX2RD,
EMC_PCHG2PDEN,
EMC_ACT2PDEN,
EMC_AR2PDEN,
EMC_RW2PDEN,
EMC_TXSR,
EMC_TCKE,
EMC_TFAW,
EMC_TRPAB,
EMC_TCLKSTABLE,
EMC_TCLKSTOP,
EMC_TREFBW,
EMC_QUSE_EXTRA,
EMC_FBIO_CFG6,
EMC_ODT_WRITE,
EMC_ODT_READ,
EMC_FBIO_CFG5,
EMC_CFG_DIG_DLL,
EMC_DLL_XFORM_DQS,
EMC_DLL_XFORM_QUSE,
EMC_ZCAL_REF_CNT,
EMC_ZCAL_WAIT_CNT,
EMC_AUTO_CAL_INTERVAL,
EMC_CFG_CLKTRIM_0,
EMC_CFG_CLKTRIM_1,
EMC_CFG_CLKTRIM_2,
};
struct emc_timing {
unsigned long rate;
u32 data[ARRAY_SIZE(emc_timing_registers)];
};
struct tegra_emc {
struct device *dev;
struct notifier_block clk_nb;
struct clk *clk;
void __iomem *regs;
struct emc_timing *timings;
unsigned int num_timings;
struct {
struct dentry *root;
unsigned long min_rate;
unsigned long max_rate;
} debugfs;
};
static irqreturn_t tegra_emc_isr(int irq, void *data)
{
struct tegra_emc *emc = data;
u32 intmask = EMC_REFRESH_OVERFLOW_INT;
u32 status;
status = readl_relaxed(emc->regs + EMC_INTSTATUS) & intmask;
if (!status)
return IRQ_NONE;
/* notify about HW problem */
if (status & EMC_REFRESH_OVERFLOW_INT)
dev_err_ratelimited(emc->dev,
"refresh request overflow timeout\n");
/* clear interrupts */
writel_relaxed(status, emc->regs + EMC_INTSTATUS);
return IRQ_HANDLED;
}
static struct emc_timing *tegra_emc_find_timing(struct tegra_emc *emc,
unsigned long rate)
{
struct emc_timing *timing = NULL;
unsigned int i;
for (i = 0; i < emc->num_timings; i++) {
if (emc->timings[i].rate >= rate) {
timing = &emc->timings[i];
break;
}
}
if (!timing) {
dev_err(emc->dev, "no timing for rate %lu\n", rate);
return NULL;
}
return timing;
}
static int emc_prepare_timing_change(struct tegra_emc *emc, unsigned long rate)
{
struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
unsigned int i;
if (!timing)
return -EINVAL;
dev_dbg(emc->dev, "%s: using timing rate %lu for requested rate %lu\n",
__func__, timing->rate, rate);
/* program shadow registers */
for (i = 0; i < ARRAY_SIZE(timing->data); i++)
writel_relaxed(timing->data[i],
emc->regs + emc_timing_registers[i]);
/* wait until programming has settled */
readl_relaxed(emc->regs + emc_timing_registers[i - 1]);
return 0;
}
static int emc_complete_timing_change(struct tegra_emc *emc, bool flush)
{
int err;
u32 v;
dev_dbg(emc->dev, "%s: flush %d\n", __func__, flush);
if (flush) {
/* manually initiate memory timing update */
writel_relaxed(EMC_TIMING_UPDATE,
emc->regs + EMC_TIMING_CONTROL);
return 0;
}
err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_INTSTATUS, v,
v & EMC_CLKCHANGE_COMPLETE_INT,
1, 100);
if (err) {
dev_err(emc->dev, "emc-car handshake timeout: %d\n", err);
return err;
}
return 0;
}
static int tegra_emc_clk_change_notify(struct notifier_block *nb,
unsigned long msg, void *data)
{
struct tegra_emc *emc = container_of(nb, struct tegra_emc, clk_nb);
struct clk_notifier_data *cnd = data;
int err;
switch (msg) {
case PRE_RATE_CHANGE:
err = emc_prepare_timing_change(emc, cnd->new_rate);
break;
case ABORT_RATE_CHANGE:
err = emc_prepare_timing_change(emc, cnd->old_rate);
if (err)
break;
err = emc_complete_timing_change(emc, true);
break;
case POST_RATE_CHANGE:
err = emc_complete_timing_change(emc, false);
break;
default:
return NOTIFY_DONE;
}
return notifier_from_errno(err);
}
static int load_one_timing_from_dt(struct tegra_emc *emc,
struct emc_timing *timing,
struct device_node *node)
{
u32 rate;
int err;
if (!of_device_is_compatible(node, "nvidia,tegra20-emc-table")) {
dev_err(emc->dev, "incompatible DT node: %pOF\n", node);
return -EINVAL;
}
err = of_property_read_u32(node, "clock-frequency", &rate);
if (err) {
dev_err(emc->dev, "timing %pOF: failed to read rate: %d\n",
node, err);
return err;
}
err = of_property_read_u32_array(node, "nvidia,emc-registers",
timing->data,
ARRAY_SIZE(emc_timing_registers));
if (err) {
dev_err(emc->dev,
"timing %pOF: failed to read emc timing data: %d\n",
node, err);
return err;
}
/*
* The EMC clock rate is twice the bus rate, and the bus rate is
* measured in kHz.
*/
timing->rate = rate * 2 * 1000;
dev_dbg(emc->dev, "%s: %pOF: EMC rate %lu\n",
__func__, node, timing->rate);
return 0;
}
static int cmp_timings(const void *_a, const void *_b)
{
const struct emc_timing *a = _a;
const struct emc_timing *b = _b;
if (a->rate < b->rate)
return -1;
if (a->rate > b->rate)
return 1;
return 0;
}
static int tegra_emc_load_timings_from_dt(struct tegra_emc *emc,
struct device_node *node)
{
struct device_node *child;
struct emc_timing *timing;
int child_count;
int err;
child_count = of_get_child_count(node);
if (!child_count) {
dev_err(emc->dev, "no memory timings in DT node: %pOF\n", node);
return -EINVAL;
}
emc->timings = devm_kcalloc(emc->dev, child_count, sizeof(*timing),
GFP_KERNEL);
if (!emc->timings)
return -ENOMEM;
emc->num_timings = child_count;
timing = emc->timings;
for_each_child_of_node(node, child) {
err = load_one_timing_from_dt(emc, timing++, child);
if (err) {
of_node_put(child);
return err;
}
}
sort(emc->timings, emc->num_timings, sizeof(*timing), cmp_timings,
NULL);
dev_info(emc->dev,
"got %u timings for RAM code %u (min %luMHz max %luMHz)\n",
emc->num_timings,
tegra_read_ram_code(),
emc->timings[0].rate / 1000000,
emc->timings[emc->num_timings - 1].rate / 1000000);
return 0;
}
static struct device_node *
tegra_emc_find_node_by_ram_code(struct device *dev)
{
struct device_node *np;
u32 value, ram_code;
int err;
if (!of_property_read_bool(dev->of_node, "nvidia,use-ram-code"))
return of_node_get(dev->of_node);
ram_code = tegra_read_ram_code();
for (np = of_find_node_by_name(dev->of_node, "emc-tables"); np;
np = of_find_node_by_name(np, "emc-tables")) {
err = of_property_read_u32(np, "nvidia,ram-code", &value);
if (err || value != ram_code) {
of_node_put(np);
continue;
}
return np;
}
dev_err(dev, "no memory timings for RAM code %u found in device tree\n",
ram_code);
return NULL;
}
static int emc_setup_hw(struct tegra_emc *emc)
{
u32 intmask = EMC_REFRESH_OVERFLOW_INT;
u32 emc_cfg, emc_dbg;
emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
/*
* Depending on a memory type, DRAM should enter either self-refresh
* or power-down state on EMC clock change.
*/
if (!(emc_cfg & EMC_CLKCHANGE_PD_ENABLE) &&
!(emc_cfg & EMC_CLKCHANGE_SR_ENABLE)) {
dev_err(emc->dev,
"bootloader didn't specify DRAM auto-suspend mode\n");
return -EINVAL;
}
/* enable EMC and CAR to handshake on PLL divider/source changes */
emc_cfg |= EMC_CLKCHANGE_REQ_ENABLE;
writel_relaxed(emc_cfg, emc->regs + EMC_CFG_2);
/* initialize interrupt */
writel_relaxed(intmask, emc->regs + EMC_INTMASK);
writel_relaxed(intmask, emc->regs + EMC_INTSTATUS);
/* ensure that unwanted debug features are disabled */
emc_dbg = readl_relaxed(emc->regs + EMC_DBG);
emc_dbg |= EMC_DBG_CFG_PRIORITY;
emc_dbg &= ~EMC_DBG_READ_MUX_ASSEMBLY;
emc_dbg &= ~EMC_DBG_WRITE_MUX_ACTIVE;
emc_dbg &= ~EMC_DBG_FORCE_UPDATE;
writel_relaxed(emc_dbg, emc->regs + EMC_DBG);
return 0;
}
static long emc_round_rate(unsigned long rate,
unsigned long min_rate,
unsigned long max_rate,
void *arg)
{
struct emc_timing *timing = NULL;
struct tegra_emc *emc = arg;
unsigned int i;
min_rate = min(min_rate, emc->timings[emc->num_timings - 1].rate);
for (i = 0; i < emc->num_timings; i++) {
if (emc->timings[i].rate < rate && i != emc->num_timings - 1)
continue;
if (emc->timings[i].rate > max_rate) {
i = max(i, 1u) - 1;
if (emc->timings[i].rate < min_rate)
break;
}
if (emc->timings[i].rate < min_rate)
continue;
timing = &emc->timings[i];
break;
}
if (!timing) {
dev_err(emc->dev, "no timing for rate %lu min %lu max %lu\n",
rate, min_rate, max_rate);
return -EINVAL;
}
return timing->rate;
}
/*
* debugfs interface
*
* The memory controller driver exposes some files in debugfs that can be used
* to control the EMC frequency. The top-level directory can be found here:
*
* /sys/kernel/debug/emc
*
* It contains the following files:
*
* - available_rates: This file contains a list of valid, space-separated
* EMC frequencies.
*
* - min_rate: Writing a value to this file sets the given frequency as the
* floor of the permitted range. If this is higher than the currently
* configured EMC frequency, this will cause the frequency to be
* increased so that it stays within the valid range.
*
* - max_rate: Similarily to the min_rate file, writing a value to this file
* sets the given frequency as the ceiling of the permitted range. If
* the value is lower than the currently configured EMC frequency, this
* will cause the frequency to be decreased so that it stays within the
* valid range.
*/
static bool tegra_emc_validate_rate(struct tegra_emc *emc, unsigned long rate)
{
unsigned int i;
for (i = 0; i < emc->num_timings; i++)
if (rate == emc->timings[i].rate)
return true;
return false;
}
static int tegra_emc_debug_available_rates_show(struct seq_file *s, void *data)
{
struct tegra_emc *emc = s->private;
const char *prefix = "";
unsigned int i;
for (i = 0; i < emc->num_timings; i++) {
seq_printf(s, "%s%lu", prefix, emc->timings[i].rate);
prefix = " ";
}
seq_puts(s, "\n");
return 0;
}
static int tegra_emc_debug_available_rates_open(struct inode *inode,
struct file *file)
{
return single_open(file, tegra_emc_debug_available_rates_show,
inode->i_private);
}
static const struct file_operations tegra_emc_debug_available_rates_fops = {
.open = tegra_emc_debug_available_rates_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int tegra_emc_debug_min_rate_get(void *data, u64 *rate)
{
struct tegra_emc *emc = data;
*rate = emc->debugfs.min_rate;
return 0;
}
static int tegra_emc_debug_min_rate_set(void *data, u64 rate)
{
struct tegra_emc *emc = data;
int err;
if (!tegra_emc_validate_rate(emc, rate))
return -EINVAL;
err = clk_set_min_rate(emc->clk, rate);
if (err < 0)
return err;
emc->debugfs.min_rate = rate;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_min_rate_fops,
tegra_emc_debug_min_rate_get,
tegra_emc_debug_min_rate_set, "%llu\n");
static int tegra_emc_debug_max_rate_get(void *data, u64 *rate)
{
struct tegra_emc *emc = data;
*rate = emc->debugfs.max_rate;
return 0;
}
static int tegra_emc_debug_max_rate_set(void *data, u64 rate)
{
struct tegra_emc *emc = data;
int err;
if (!tegra_emc_validate_rate(emc, rate))
return -EINVAL;
err = clk_set_max_rate(emc->clk, rate);
if (err < 0)
return err;
emc->debugfs.max_rate = rate;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_max_rate_fops,
tegra_emc_debug_max_rate_get,
tegra_emc_debug_max_rate_set, "%llu\n");
static void tegra_emc_debugfs_init(struct tegra_emc *emc)
{
struct device *dev = emc->dev;
unsigned int i;
int err;
emc->debugfs.min_rate = ULONG_MAX;
emc->debugfs.max_rate = 0;
for (i = 0; i < emc->num_timings; i++) {
if (emc->timings[i].rate < emc->debugfs.min_rate)
emc->debugfs.min_rate = emc->timings[i].rate;
if (emc->timings[i].rate > emc->debugfs.max_rate)
emc->debugfs.max_rate = emc->timings[i].rate;
}
if (!emc->num_timings) {
emc->debugfs.min_rate = clk_get_rate(emc->clk);
emc->debugfs.max_rate = emc->debugfs.min_rate;
}
err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
emc->debugfs.max_rate);
if (err < 0) {
dev_err(dev, "failed to set rate range [%lu-%lu] for %pC\n",
emc->debugfs.min_rate, emc->debugfs.max_rate,
emc->clk);
}
emc->debugfs.root = debugfs_create_dir("emc", NULL);
if (!emc->debugfs.root) {
dev_err(emc->dev, "failed to create debugfs directory\n");
return;
}
debugfs_create_file("available_rates", 0444, emc->debugfs.root,
emc, &tegra_emc_debug_available_rates_fops);
debugfs_create_file("min_rate", 0644, emc->debugfs.root,
emc, &tegra_emc_debug_min_rate_fops);
debugfs_create_file("max_rate", 0644, emc->debugfs.root,
emc, &tegra_emc_debug_max_rate_fops);
}
static int tegra_emc_probe(struct platform_device *pdev)
{
struct device_node *np;
struct tegra_emc *emc;
struct resource *res;
int irq, err;
/* driver has nothing to do in a case of memory timing absence */
if (of_get_child_count(pdev->dev.of_node) == 0) {
dev_info(&pdev->dev,
"EMC device tree node doesn't have memory timings\n");
return 0;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "interrupt not specified\n");
dev_err(&pdev->dev, "please update your device tree\n");
return irq;
}
np = tegra_emc_find_node_by_ram_code(&pdev->dev);
if (!np)
return -EINVAL;
emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
if (!emc) {
of_node_put(np);
return -ENOMEM;
}
emc->clk_nb.notifier_call = tegra_emc_clk_change_notify;
emc->dev = &pdev->dev;
err = tegra_emc_load_timings_from_dt(emc, np);
of_node_put(np);
if (err)
return err;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
emc->regs = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(emc->regs))
return PTR_ERR(emc->regs);
err = emc_setup_hw(emc);
if (err)
return err;
err = devm_request_irq(&pdev->dev, irq, tegra_emc_isr, 0,
dev_name(&pdev->dev), emc);
if (err) {
dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n", irq, err);
return err;
}
tegra20_clk_set_emc_round_callback(emc_round_rate, emc);
emc->clk = devm_clk_get(&pdev->dev, "emc");
if (IS_ERR(emc->clk)) {
err = PTR_ERR(emc->clk);
dev_err(&pdev->dev, "failed to get emc clock: %d\n", err);
goto unset_cb;
}
err = clk_notifier_register(emc->clk, &emc->clk_nb);
if (err) {
dev_err(&pdev->dev, "failed to register clk notifier: %d\n",
err);
goto unset_cb;
}
platform_set_drvdata(pdev, emc);
tegra_emc_debugfs_init(emc);
return 0;
unset_cb:
tegra20_clk_set_emc_round_callback(NULL, NULL);
return err;
}
static const struct of_device_id tegra_emc_of_match[] = {
{ .compatible = "nvidia,tegra20-emc", },
{},
};
static struct platform_driver tegra_emc_driver = {
.probe = tegra_emc_probe,
.driver = {
.name = "tegra20-emc",
.of_match_table = tegra_emc_of_match,
.suppress_bind_attrs = true,
},
};
static int __init tegra_emc_init(void)
{
return platform_driver_register(&tegra_emc_driver);
}
subsys_initcall(tegra_emc_init);