linux/drivers/memory/tegra/tegra30-emc.c

1435 lines
35 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Tegra30 External Memory Controller driver
*
* Based on downstream driver from NVIDIA and tegra124-emc.c
* Copyright (C) 2011-2014 NVIDIA Corporation
*
* Author: Dmitry Osipenko <digetx@gmail.com>
* Copyright (C) 2019 GRATE-DRIVER project
*/
#include <linux/clk.h>
#include <linux/clk/tegra.h>
#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/delay.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_platform.h>
#include <linux/platform_device.h>
#include <linux/sort.h>
#include <linux/types.h>
#include <soc/tegra/fuse.h>
#include "mc.h"
#define EMC_INTSTATUS 0x000
#define EMC_INTMASK 0x004
#define EMC_DBG 0x008
#define EMC_CFG 0x00c
#define EMC_REFCTRL 0x020
#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_WEXT 0x0b8
#define EMC_CTT 0x0bc
#define EMC_MRS_WAIT_CNT 0x0c8
#define EMC_MRS 0x0cc
#define EMC_EMRS 0x0d0
#define EMC_SELF_REF 0x0e0
#define EMC_MRW 0x0e8
#define EMC_XM2DQSPADCTRL3 0x0f8
#define EMC_FBIO_SPARE 0x100
#define EMC_FBIO_CFG5 0x104
#define EMC_FBIO_CFG6 0x114
#define EMC_CFG_RSV 0x120
#define EMC_AUTO_CAL_CONFIG 0x2a4
#define EMC_AUTO_CAL_INTERVAL 0x2a8
#define EMC_AUTO_CAL_STATUS 0x2ac
#define EMC_STATUS 0x2b4
#define EMC_CFG_2 0x2b8
#define EMC_CFG_DIG_DLL 0x2bc
#define EMC_CFG_DIG_DLL_PERIOD 0x2c0
#define EMC_CTT_DURATION 0x2d8
#define EMC_CTT_TERM_CTRL 0x2dc
#define EMC_ZCAL_INTERVAL 0x2e0
#define EMC_ZCAL_WAIT_CNT 0x2e4
#define EMC_ZQ_CAL 0x2ec
#define EMC_XM2CMDPADCTRL 0x2f0
#define EMC_XM2DQSPADCTRL2 0x2fc
#define EMC_XM2DQPADCTRL2 0x304
#define EMC_XM2CLKPADCTRL 0x308
#define EMC_XM2COMPPADCTRL 0x30c
#define EMC_XM2VTTGENPADCTRL 0x310
#define EMC_XM2VTTGENPADCTRL2 0x314
#define EMC_XM2QUSEPADCTRL 0x318
#define EMC_DLL_XFORM_DQS0 0x328
#define EMC_DLL_XFORM_DQS1 0x32c
#define EMC_DLL_XFORM_DQS2 0x330
#define EMC_DLL_XFORM_DQS3 0x334
#define EMC_DLL_XFORM_DQS4 0x338
#define EMC_DLL_XFORM_DQS5 0x33c
#define EMC_DLL_XFORM_DQS6 0x340
#define EMC_DLL_XFORM_DQS7 0x344
#define EMC_DLL_XFORM_QUSE0 0x348
#define EMC_DLL_XFORM_QUSE1 0x34c
#define EMC_DLL_XFORM_QUSE2 0x350
#define EMC_DLL_XFORM_QUSE3 0x354
#define EMC_DLL_XFORM_QUSE4 0x358
#define EMC_DLL_XFORM_QUSE5 0x35c
#define EMC_DLL_XFORM_QUSE6 0x360
#define EMC_DLL_XFORM_QUSE7 0x364
#define EMC_DLL_XFORM_DQ0 0x368
#define EMC_DLL_XFORM_DQ1 0x36c
#define EMC_DLL_XFORM_DQ2 0x370
#define EMC_DLL_XFORM_DQ3 0x374
#define EMC_DLI_TRIM_TXDQS0 0x3a8
#define EMC_DLI_TRIM_TXDQS1 0x3ac
#define EMC_DLI_TRIM_TXDQS2 0x3b0
#define EMC_DLI_TRIM_TXDQS3 0x3b4
#define EMC_DLI_TRIM_TXDQS4 0x3b8
#define EMC_DLI_TRIM_TXDQS5 0x3bc
#define EMC_DLI_TRIM_TXDQS6 0x3c0
#define EMC_DLI_TRIM_TXDQS7 0x3c4
#define EMC_STALL_THEN_EXE_BEFORE_CLKCHANGE 0x3c8
#define EMC_STALL_THEN_EXE_AFTER_CLKCHANGE 0x3cc
#define EMC_UNSTALL_RW_AFTER_CLKCHANGE 0x3d0
#define EMC_SEL_DPD_CTRL 0x3d8
#define EMC_PRE_REFRESH_REQ_CNT 0x3dc
#define EMC_DYN_SELF_REF_CONTROL 0x3e0
#define EMC_TXSRDLL 0x3e4
#define EMC_STATUS_TIMING_UPDATE_STALLED BIT(23)
#define EMC_MODE_SET_DLL_RESET BIT(8)
#define EMC_MODE_SET_LONG_CNT BIT(26)
#define EMC_SELF_REF_CMD_ENABLED BIT(0)
#define DRAM_DEV_SEL_ALL (0 << 30)
#define DRAM_DEV_SEL_0 (2 << 30)
#define DRAM_DEV_SEL_1 (1 << 30)
#define DRAM_BROADCAST(num) \
((num) > 1 ? DRAM_DEV_SEL_ALL : DRAM_DEV_SEL_0)
#define EMC_ZQ_CAL_CMD BIT(0)
#define EMC_ZQ_CAL_LONG BIT(4)
#define EMC_ZQ_CAL_LONG_CMD_DEV0 \
(DRAM_DEV_SEL_0 | EMC_ZQ_CAL_LONG | EMC_ZQ_CAL_CMD)
#define EMC_ZQ_CAL_LONG_CMD_DEV1 \
(DRAM_DEV_SEL_1 | EMC_ZQ_CAL_LONG | EMC_ZQ_CAL_CMD)
#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_CFG_PRIORITY BIT(24)
#define EMC_CFG5_QUSE_MODE_SHIFT 13
#define EMC_CFG5_QUSE_MODE_MASK (7 << EMC_CFG5_QUSE_MODE_SHIFT)
#define EMC_CFG5_QUSE_MODE_INTERNAL_LPBK 2
#define EMC_CFG5_QUSE_MODE_PULSE_INTERN 3
#define EMC_SEL_DPD_CTRL_QUSE_DPD_ENABLE BIT(9)
#define EMC_XM2COMPPADCTRL_VREF_CAL_ENABLE BIT(10)
#define EMC_XM2QUSEPADCTRL_IVREF_ENABLE BIT(4)
#define EMC_XM2DQSPADCTRL2_VREF_ENABLE BIT(5)
#define EMC_XM2DQSPADCTRL3_VREF_ENABLE BIT(5)
#define EMC_AUTO_CAL_STATUS_ACTIVE BIT(31)
#define EMC_FBIO_CFG5_DRAM_TYPE_MASK 0x3
#define EMC_MRS_WAIT_CNT_SHORT_WAIT_MASK 0x3ff
#define EMC_MRS_WAIT_CNT_LONG_WAIT_SHIFT 16
#define EMC_MRS_WAIT_CNT_LONG_WAIT_MASK \
(0x3ff << EMC_MRS_WAIT_CNT_LONG_WAIT_SHIFT)
#define EMC_REFCTRL_DEV_SEL_MASK 0x3
#define EMC_REFCTRL_ENABLE BIT(31)
#define EMC_REFCTRL_ENABLE_ALL(num) \
(((num) > 1 ? 0 : 2) | EMC_REFCTRL_ENABLE)
#define EMC_REFCTRL_DISABLE_ALL(num) ((num) > 1 ? 0 : 2)
#define EMC_CFG_PERIODIC_QRST BIT(21)
#define EMC_CFG_DYN_SREF_ENABLE BIT(28)
#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)
enum emc_dram_type {
DRAM_TYPE_DDR3,
DRAM_TYPE_DDR1,
DRAM_TYPE_LPDDR2,
DRAM_TYPE_DDR2,
};
enum emc_dll_change {
DLL_CHANGE_NONE,
DLL_CHANGE_ON,
DLL_CHANGE_OFF
};
static const u16 emc_timing_registers[] = {
[0] = EMC_RC,
[1] = EMC_RFC,
[2] = EMC_RAS,
[3] = EMC_RP,
[4] = EMC_R2W,
[5] = EMC_W2R,
[6] = EMC_R2P,
[7] = EMC_W2P,
[8] = EMC_RD_RCD,
[9] = EMC_WR_RCD,
[10] = EMC_RRD,
[11] = EMC_REXT,
[12] = EMC_WEXT,
[13] = EMC_WDV,
[14] = EMC_QUSE,
[15] = EMC_QRST,
[16] = EMC_QSAFE,
[17] = EMC_RDV,
[18] = EMC_REFRESH,
[19] = EMC_BURST_REFRESH_NUM,
[20] = EMC_PRE_REFRESH_REQ_CNT,
[21] = EMC_PDEX2WR,
[22] = EMC_PDEX2RD,
[23] = EMC_PCHG2PDEN,
[24] = EMC_ACT2PDEN,
[25] = EMC_AR2PDEN,
[26] = EMC_RW2PDEN,
[27] = EMC_TXSR,
[28] = EMC_TXSRDLL,
[29] = EMC_TCKE,
[30] = EMC_TFAW,
[31] = EMC_TRPAB,
[32] = EMC_TCLKSTABLE,
[33] = EMC_TCLKSTOP,
[34] = EMC_TREFBW,
[35] = EMC_QUSE_EXTRA,
[36] = EMC_FBIO_CFG6,
[37] = EMC_ODT_WRITE,
[38] = EMC_ODT_READ,
[39] = EMC_FBIO_CFG5,
[40] = EMC_CFG_DIG_DLL,
[41] = EMC_CFG_DIG_DLL_PERIOD,
[42] = EMC_DLL_XFORM_DQS0,
[43] = EMC_DLL_XFORM_DQS1,
[44] = EMC_DLL_XFORM_DQS2,
[45] = EMC_DLL_XFORM_DQS3,
[46] = EMC_DLL_XFORM_DQS4,
[47] = EMC_DLL_XFORM_DQS5,
[48] = EMC_DLL_XFORM_DQS6,
[49] = EMC_DLL_XFORM_DQS7,
[50] = EMC_DLL_XFORM_QUSE0,
[51] = EMC_DLL_XFORM_QUSE1,
[52] = EMC_DLL_XFORM_QUSE2,
[53] = EMC_DLL_XFORM_QUSE3,
[54] = EMC_DLL_XFORM_QUSE4,
[55] = EMC_DLL_XFORM_QUSE5,
[56] = EMC_DLL_XFORM_QUSE6,
[57] = EMC_DLL_XFORM_QUSE7,
[58] = EMC_DLI_TRIM_TXDQS0,
[59] = EMC_DLI_TRIM_TXDQS1,
[60] = EMC_DLI_TRIM_TXDQS2,
[61] = EMC_DLI_TRIM_TXDQS3,
[62] = EMC_DLI_TRIM_TXDQS4,
[63] = EMC_DLI_TRIM_TXDQS5,
[64] = EMC_DLI_TRIM_TXDQS6,
[65] = EMC_DLI_TRIM_TXDQS7,
[66] = EMC_DLL_XFORM_DQ0,
[67] = EMC_DLL_XFORM_DQ1,
[68] = EMC_DLL_XFORM_DQ2,
[69] = EMC_DLL_XFORM_DQ3,
[70] = EMC_XM2CMDPADCTRL,
[71] = EMC_XM2DQSPADCTRL2,
[72] = EMC_XM2DQPADCTRL2,
[73] = EMC_XM2CLKPADCTRL,
[74] = EMC_XM2COMPPADCTRL,
[75] = EMC_XM2VTTGENPADCTRL,
[76] = EMC_XM2VTTGENPADCTRL2,
[77] = EMC_XM2QUSEPADCTRL,
[78] = EMC_XM2DQSPADCTRL3,
[79] = EMC_CTT_TERM_CTRL,
[80] = EMC_ZCAL_INTERVAL,
[81] = EMC_ZCAL_WAIT_CNT,
[82] = EMC_MRS_WAIT_CNT,
[83] = EMC_AUTO_CAL_CONFIG,
[84] = EMC_CTT,
[85] = EMC_CTT_DURATION,
[86] = EMC_DYN_SELF_REF_CONTROL,
[87] = EMC_FBIO_SPARE,
[88] = EMC_CFG_RSV,
};
struct emc_timing {
unsigned long rate;
u32 data[ARRAY_SIZE(emc_timing_registers)];
u32 emc_auto_cal_interval;
u32 emc_mode_1;
u32 emc_mode_2;
u32 emc_mode_reset;
u32 emc_zcal_cnt_long;
bool emc_cfg_periodic_qrst;
bool emc_cfg_dyn_self_ref;
};
struct tegra_emc {
struct device *dev;
struct tegra_mc *mc;
struct completion clk_handshake_complete;
struct notifier_block clk_nb;
struct clk *clk;
void __iomem *regs;
unsigned int irq;
bool bad_state;
struct emc_timing *new_timing;
struct emc_timing *timings;
unsigned int num_timings;
u32 mc_override;
u32 emc_cfg;
u32 emc_mode_1;
u32 emc_mode_2;
u32 emc_mode_reset;
bool vref_cal_toggle : 1;
bool zcal_long : 1;
bool dll_on : 1;
struct {
struct dentry *root;
unsigned long min_rate;
unsigned long max_rate;
} debugfs;
};
static int emc_seq_update_timing(struct tegra_emc *emc)
{
u32 val;
int err;
writel_relaxed(EMC_TIMING_UPDATE, emc->regs + EMC_TIMING_CONTROL);
err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_STATUS, val,
!(val & EMC_STATUS_TIMING_UPDATE_STALLED),
1, 200);
if (err) {
dev_err(emc->dev, "failed to update timing: %d\n", err);
return err;
}
return 0;
}
static void emc_complete_clk_change(struct tegra_emc *emc)
{
struct emc_timing *timing = emc->new_timing;
unsigned int dram_num;
bool failed = false;
int err;
/* re-enable auto-refresh */
dram_num = tegra_mc_get_emem_device_count(emc->mc);
writel_relaxed(EMC_REFCTRL_ENABLE_ALL(dram_num),
emc->regs + EMC_REFCTRL);
/* restore auto-calibration */
if (emc->vref_cal_toggle)
writel_relaxed(timing->emc_auto_cal_interval,
emc->regs + EMC_AUTO_CAL_INTERVAL);
/* restore dynamic self-refresh */
if (timing->emc_cfg_dyn_self_ref) {
emc->emc_cfg |= EMC_CFG_DYN_SREF_ENABLE;
writel_relaxed(emc->emc_cfg, emc->regs + EMC_CFG);
}
/* set number of clocks to wait after each ZQ command */
if (emc->zcal_long)
writel_relaxed(timing->emc_zcal_cnt_long,
emc->regs + EMC_ZCAL_WAIT_CNT);
/* wait for writes to settle */
udelay(2);
/* update restored timing */
err = emc_seq_update_timing(emc);
if (err)
failed = true;
/* restore early ACK */
mc_writel(emc->mc, emc->mc_override, MC_EMEM_ARB_OVERRIDE);
WRITE_ONCE(emc->bad_state, failed);
}
static irqreturn_t tegra_emc_isr(int irq, void *data)
{
struct tegra_emc *emc = data;
u32 intmask = EMC_REFRESH_OVERFLOW_INT | EMC_CLKCHANGE_COMPLETE_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);
/* notify about EMC-CAR handshake completion */
if (status & EMC_CLKCHANGE_COMPLETE_INT) {
if (completion_done(&emc->clk_handshake_complete)) {
dev_err_ratelimited(emc->dev,
"bogus handshake interrupt\n");
return IRQ_NONE;
}
emc_complete_clk_change(emc);
complete(&emc->clk_handshake_complete);
}
return IRQ_HANDLED;
}
static struct emc_timing *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 bool emc_dqs_preset(struct tegra_emc *emc, struct emc_timing *timing,
bool *schmitt_to_vref)
{
bool preset = false;
u32 val;
if (timing->data[71] & EMC_XM2DQSPADCTRL2_VREF_ENABLE) {
val = readl_relaxed(emc->regs + EMC_XM2DQSPADCTRL2);
if (!(val & EMC_XM2DQSPADCTRL2_VREF_ENABLE)) {
val |= EMC_XM2DQSPADCTRL2_VREF_ENABLE;
writel_relaxed(val, emc->regs + EMC_XM2DQSPADCTRL2);
preset = true;
}
}
if (timing->data[78] & EMC_XM2DQSPADCTRL3_VREF_ENABLE) {
val = readl_relaxed(emc->regs + EMC_XM2DQSPADCTRL3);
if (!(val & EMC_XM2DQSPADCTRL3_VREF_ENABLE)) {
val |= EMC_XM2DQSPADCTRL3_VREF_ENABLE;
writel_relaxed(val, emc->regs + EMC_XM2DQSPADCTRL3);
preset = true;
}
}
if (timing->data[77] & EMC_XM2QUSEPADCTRL_IVREF_ENABLE) {
val = readl_relaxed(emc->regs + EMC_XM2QUSEPADCTRL);
if (!(val & EMC_XM2QUSEPADCTRL_IVREF_ENABLE)) {
val |= EMC_XM2QUSEPADCTRL_IVREF_ENABLE;
writel_relaxed(val, emc->regs + EMC_XM2QUSEPADCTRL);
*schmitt_to_vref = true;
preset = true;
}
}
return preset;
}
static int emc_prepare_mc_clk_cfg(struct tegra_emc *emc, unsigned long rate)
{
struct tegra_mc *mc = emc->mc;
unsigned int misc0_index = 16;
unsigned int i;
bool same;
for (i = 0; i < mc->num_timings; i++) {
if (mc->timings[i].rate != rate)
continue;
if (mc->timings[i].emem_data[misc0_index] & BIT(27))
same = true;
else
same = false;
return tegra20_clk_prepare_emc_mc_same_freq(emc->clk, same);
}
return -EINVAL;
}
static int emc_prepare_timing_change(struct tegra_emc *emc, unsigned long rate)
{
struct emc_timing *timing = emc_find_timing(emc, rate);
enum emc_dll_change dll_change;
enum emc_dram_type dram_type;
bool schmitt_to_vref = false;
unsigned int pre_wait = 0;
bool qrst_used = false;
unsigned int dram_num;
unsigned int i;
u32 fbio_cfg5;
u32 emc_dbg;
u32 val;
int err;
if (!timing || emc->bad_state)
return -EINVAL;
dev_dbg(emc->dev, "%s: using timing rate %lu for requested rate %lu\n",
__func__, timing->rate, rate);
emc->bad_state = true;
err = emc_prepare_mc_clk_cfg(emc, rate);
if (err) {
dev_err(emc->dev, "mc clock preparation failed: %d\n", err);
return err;
}
emc->vref_cal_toggle = false;
emc->mc_override = mc_readl(emc->mc, MC_EMEM_ARB_OVERRIDE);
emc->emc_cfg = readl_relaxed(emc->regs + EMC_CFG);
emc_dbg = readl_relaxed(emc->regs + EMC_DBG);
if (emc->dll_on == !!(timing->emc_mode_1 & 0x1))
dll_change = DLL_CHANGE_NONE;
else if (timing->emc_mode_1 & 0x1)
dll_change = DLL_CHANGE_ON;
else
dll_change = DLL_CHANGE_OFF;
emc->dll_on = !!(timing->emc_mode_1 & 0x1);
if (timing->data[80] && !readl_relaxed(emc->regs + EMC_ZCAL_INTERVAL))
emc->zcal_long = true;
else
emc->zcal_long = false;
fbio_cfg5 = readl_relaxed(emc->regs + EMC_FBIO_CFG5);
dram_type = fbio_cfg5 & EMC_FBIO_CFG5_DRAM_TYPE_MASK;
dram_num = tegra_mc_get_emem_device_count(emc->mc);
/* disable dynamic self-refresh */
if (emc->emc_cfg & EMC_CFG_DYN_SREF_ENABLE) {
emc->emc_cfg &= ~EMC_CFG_DYN_SREF_ENABLE;
writel_relaxed(emc->emc_cfg, emc->regs + EMC_CFG);
pre_wait = 5;
}
/* update MC arbiter settings */
val = mc_readl(emc->mc, MC_EMEM_ARB_OUTSTANDING_REQ);
if (!(val & MC_EMEM_ARB_OUTSTANDING_REQ_HOLDOFF_OVERRIDE) ||
((val & MC_EMEM_ARB_OUTSTANDING_REQ_MAX_MASK) > 0x50)) {
val = MC_EMEM_ARB_OUTSTANDING_REQ_LIMIT_ENABLE |
MC_EMEM_ARB_OUTSTANDING_REQ_HOLDOFF_OVERRIDE | 0x50;
mc_writel(emc->mc, val, MC_EMEM_ARB_OUTSTANDING_REQ);
mc_writel(emc->mc, MC_TIMING_UPDATE, MC_TIMING_CONTROL);
}
if (emc->mc_override & MC_EMEM_ARB_OVERRIDE_EACK_MASK)
mc_writel(emc->mc,
emc->mc_override & ~MC_EMEM_ARB_OVERRIDE_EACK_MASK,
MC_EMEM_ARB_OVERRIDE);
/* check DQ/DQS VREF delay */
if (emc_dqs_preset(emc, timing, &schmitt_to_vref)) {
if (pre_wait < 3)
pre_wait = 3;
}
if (pre_wait) {
err = emc_seq_update_timing(emc);
if (err)
return err;
udelay(pre_wait);
}
/* disable auto-calibration if VREF mode is switching */
if (timing->emc_auto_cal_interval) {
val = readl_relaxed(emc->regs + EMC_XM2COMPPADCTRL);
val ^= timing->data[74];
if (val & EMC_XM2COMPPADCTRL_VREF_CAL_ENABLE) {
writel_relaxed(0, emc->regs + EMC_AUTO_CAL_INTERVAL);
err = readl_relaxed_poll_timeout_atomic(
emc->regs + EMC_AUTO_CAL_STATUS, val,
!(val & EMC_AUTO_CAL_STATUS_ACTIVE), 1, 300);
if (err) {
dev_err(emc->dev,
"auto-cal finish timeout: %d\n", err);
return err;
}
emc->vref_cal_toggle = true;
}
}
/* program shadow registers */
for (i = 0; i < ARRAY_SIZE(timing->data); i++) {
/* EMC_XM2CLKPADCTRL should be programmed separately */
if (i != 73)
writel_relaxed(timing->data[i],
emc->regs + emc_timing_registers[i]);
}
err = tegra_mc_write_emem_configuration(emc->mc, timing->rate);
if (err)
return err;
/* DDR3: predict MRS long wait count */
if (dram_type == DRAM_TYPE_DDR3 && dll_change == DLL_CHANGE_ON) {
u32 cnt = 512;
if (emc->zcal_long)
cnt -= dram_num * 256;
val = timing->data[82] & EMC_MRS_WAIT_CNT_SHORT_WAIT_MASK;
if (cnt < val)
cnt = val;
val = timing->data[82] & ~EMC_MRS_WAIT_CNT_LONG_WAIT_MASK;
val |= (cnt << EMC_MRS_WAIT_CNT_LONG_WAIT_SHIFT) &
EMC_MRS_WAIT_CNT_LONG_WAIT_MASK;
writel_relaxed(val, emc->regs + EMC_MRS_WAIT_CNT);
}
/* this read also completes the writes */
val = readl_relaxed(emc->regs + EMC_SEL_DPD_CTRL);
if (!(val & EMC_SEL_DPD_CTRL_QUSE_DPD_ENABLE) && schmitt_to_vref) {
u32 cur_mode, new_mode;
cur_mode = fbio_cfg5 & EMC_CFG5_QUSE_MODE_MASK;
cur_mode >>= EMC_CFG5_QUSE_MODE_SHIFT;
new_mode = timing->data[39] & EMC_CFG5_QUSE_MODE_MASK;
new_mode >>= EMC_CFG5_QUSE_MODE_SHIFT;
if ((cur_mode != EMC_CFG5_QUSE_MODE_PULSE_INTERN &&
cur_mode != EMC_CFG5_QUSE_MODE_INTERNAL_LPBK) ||
(new_mode != EMC_CFG5_QUSE_MODE_PULSE_INTERN &&
new_mode != EMC_CFG5_QUSE_MODE_INTERNAL_LPBK))
qrst_used = true;
}
/* flow control marker 1 */
writel_relaxed(0x1, emc->regs + EMC_STALL_THEN_EXE_BEFORE_CLKCHANGE);
/* enable periodic reset */
if (qrst_used) {
writel_relaxed(emc_dbg | EMC_DBG_WRITE_MUX_ACTIVE,
emc->regs + EMC_DBG);
writel_relaxed(emc->emc_cfg | EMC_CFG_PERIODIC_QRST,
emc->regs + EMC_CFG);
writel_relaxed(emc_dbg, emc->regs + EMC_DBG);
}
/* disable auto-refresh to save time after clock change */
writel_relaxed(EMC_REFCTRL_DISABLE_ALL(dram_num),
emc->regs + EMC_REFCTRL);
/* turn off DLL and enter self-refresh on DDR3 */
if (dram_type == DRAM_TYPE_DDR3) {
if (dll_change == DLL_CHANGE_OFF)
writel_relaxed(timing->emc_mode_1,
emc->regs + EMC_EMRS);
writel_relaxed(DRAM_BROADCAST(dram_num) |
EMC_SELF_REF_CMD_ENABLED,
emc->regs + EMC_SELF_REF);
}
/* flow control marker 2 */
writel_relaxed(0x1, emc->regs + EMC_STALL_THEN_EXE_AFTER_CLKCHANGE);
/* enable write-active MUX, update unshadowed pad control */
writel_relaxed(emc_dbg | EMC_DBG_WRITE_MUX_ACTIVE, emc->regs + EMC_DBG);
writel_relaxed(timing->data[73], emc->regs + EMC_XM2CLKPADCTRL);
/* restore periodic QRST and disable write-active MUX */
val = !!(emc->emc_cfg & EMC_CFG_PERIODIC_QRST);
if (qrst_used || timing->emc_cfg_periodic_qrst != val) {
if (timing->emc_cfg_periodic_qrst)
emc->emc_cfg |= EMC_CFG_PERIODIC_QRST;
else
emc->emc_cfg &= ~EMC_CFG_PERIODIC_QRST;
writel_relaxed(emc->emc_cfg, emc->regs + EMC_CFG);
}
writel_relaxed(emc_dbg, emc->regs + EMC_DBG);
/* exit self-refresh on DDR3 */
if (dram_type == DRAM_TYPE_DDR3)
writel_relaxed(DRAM_BROADCAST(dram_num),
emc->regs + EMC_SELF_REF);
/* set DRAM-mode registers */
if (dram_type == DRAM_TYPE_DDR3) {
if (timing->emc_mode_1 != emc->emc_mode_1)
writel_relaxed(timing->emc_mode_1,
emc->regs + EMC_EMRS);
if (timing->emc_mode_2 != emc->emc_mode_2)
writel_relaxed(timing->emc_mode_2,
emc->regs + EMC_EMRS);
if (timing->emc_mode_reset != emc->emc_mode_reset ||
dll_change == DLL_CHANGE_ON) {
val = timing->emc_mode_reset;
if (dll_change == DLL_CHANGE_ON) {
val |= EMC_MODE_SET_DLL_RESET;
val |= EMC_MODE_SET_LONG_CNT;
} else {
val &= ~EMC_MODE_SET_DLL_RESET;
}
writel_relaxed(val, emc->regs + EMC_MRS);
}
} else {
if (timing->emc_mode_2 != emc->emc_mode_2)
writel_relaxed(timing->emc_mode_2,
emc->regs + EMC_MRW);
if (timing->emc_mode_1 != emc->emc_mode_1)
writel_relaxed(timing->emc_mode_1,
emc->regs + EMC_MRW);
}
emc->emc_mode_1 = timing->emc_mode_1;
emc->emc_mode_2 = timing->emc_mode_2;
emc->emc_mode_reset = timing->emc_mode_reset;
/* issue ZCAL command if turning ZCAL on */
if (emc->zcal_long) {
writel_relaxed(EMC_ZQ_CAL_LONG_CMD_DEV0,
emc->regs + EMC_ZQ_CAL);
if (dram_num > 1)
writel_relaxed(EMC_ZQ_CAL_LONG_CMD_DEV1,
emc->regs + EMC_ZQ_CAL);
}
/* flow control marker 3 */
writel_relaxed(0x1, emc->regs + EMC_UNSTALL_RW_AFTER_CLKCHANGE);
/*
* Read and discard an arbitrary MC register (Note: EMC registers
* can't be used) to ensure the register writes are completed.
*/
mc_readl(emc->mc, MC_EMEM_ARB_OVERRIDE);
reinit_completion(&emc->clk_handshake_complete);
emc->new_timing = timing;
return 0;
}
static int emc_complete_timing_change(struct tegra_emc *emc,
unsigned long rate)
{
unsigned long timeout;
timeout = wait_for_completion_timeout(&emc->clk_handshake_complete,
msecs_to_jiffies(100));
if (timeout == 0) {
dev_err(emc->dev, "emc-car handshake failed\n");
return -EIO;
}
if (READ_ONCE(emc->bad_state))
return -EIO;
return 0;
}
static int emc_unprepare_timing_change(struct tegra_emc *emc,
unsigned long rate)
{
if (!emc->bad_state) {
/* shouldn't ever happen in practice */
dev_err(emc->dev, "timing configuration can't be reverted\n");
emc->bad_state = true;
}
return 0;
}
static int 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:
/*
* Disable interrupt since read accesses are prohibited after
* stalling.
*/
disable_irq(emc->irq);
err = emc_prepare_timing_change(emc, cnd->new_rate);
enable_irq(emc->irq);
break;
case ABORT_RATE_CHANGE:
err = emc_unprepare_timing_change(emc, cnd->old_rate);
break;
case POST_RATE_CHANGE:
err = emc_complete_timing_change(emc, cnd->new_rate);
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 value;
int err;
err = of_property_read_u32(node, "clock-frequency", &value);
if (err) {
dev_err(emc->dev, "timing %pOF: failed to read rate: %d\n",
node, err);
return err;
}
timing->rate = value;
err = of_property_read_u32_array(node, "nvidia,emc-configuration",
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;
}
#define EMC_READ_BOOL(prop, dtprop) \
timing->prop = of_property_read_bool(node, dtprop);
#define EMC_READ_U32(prop, dtprop) \
err = of_property_read_u32(node, dtprop, &timing->prop); \
if (err) { \
dev_err(emc->dev, \
"timing %pOFn: failed to read " #prop ": %d\n", \
node, err); \
return err; \
}
EMC_READ_U32(emc_auto_cal_interval, "nvidia,emc-auto-cal-interval")
EMC_READ_U32(emc_mode_1, "nvidia,emc-mode-1")
EMC_READ_U32(emc_mode_2, "nvidia,emc-mode-2")
EMC_READ_U32(emc_mode_reset, "nvidia,emc-mode-reset")
EMC_READ_U32(emc_zcal_cnt_long, "nvidia,emc-zcal-cnt-long")
EMC_READ_BOOL(emc_cfg_dyn_self_ref, "nvidia,emc-cfg-dyn-self-ref")
EMC_READ_BOOL(emc_cfg_periodic_qrst, "nvidia,emc-cfg-periodic-qrst")
#undef EMC_READ_U32
#undef EMC_READ_BOOL
dev_dbg(emc->dev, "%s: %pOF: 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 emc_check_mc_timings(struct tegra_emc *emc)
{
struct tegra_mc *mc = emc->mc;
unsigned int i;
if (emc->num_timings != mc->num_timings) {
dev_err(emc->dev, "emc/mc timings number mismatch: %u %u\n",
emc->num_timings, mc->num_timings);
return -EINVAL;
}
for (i = 0; i < mc->num_timings; i++) {
if (emc->timings[i].rate != mc->timings[i].rate) {
dev_err(emc->dev,
"emc/mc timing rate mismatch: %lu %lu\n",
emc->timings[i].rate, mc->timings[i].rate);
return -EINVAL;
}
}
return 0;
}
static int 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: %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);
err = emc_check_mc_timings(emc);
if (err)
return err;
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 *emc_find_node_by_ram_code(struct device *dev)
{
struct device_node *np;
u32 value, ram_code;
int err;
ram_code = tegra_read_ram_code();
for_each_child_of_node(dev->of_node, np) {
err = of_property_read_u32(np, "nvidia,ram-code", &value);
if (err || value != ram_code)
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 | EMC_CLKCHANGE_COMPLETE_INT;
u32 fbio_cfg5, emc_cfg, emc_dbg;
enum emc_dram_type dram_type;
fbio_cfg5 = readl_relaxed(emc->regs + EMC_FBIO_CFG5);
dram_type = fbio_cfg5 & EMC_FBIO_CFG5_DRAM_TYPE_MASK;
emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
/* enable EMC and CAR to handshake on PLL divider/source changes */
emc_cfg |= EMC_CLKCHANGE_REQ_ENABLE;
/* configure clock change mode accordingly to DRAM type */
switch (dram_type) {
case DRAM_TYPE_LPDDR2:
emc_cfg |= EMC_CLKCHANGE_PD_ENABLE;
emc_cfg &= ~EMC_CLKCHANGE_SR_ENABLE;
break;
default:
emc_cfg &= ~EMC_CLKCHANGE_SR_ENABLE;
emc_cfg &= ~EMC_CLKCHANGE_PD_ENABLE;
break;
}
writel_relaxed(emc_cfg, emc->regs + EMC_CFG_2);
/* initialize interrupt */
writel_relaxed(intmask, emc->regs + EMC_INTMASK);
writel_relaxed(0xffffffff, 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;
}
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", S_IRUGO, emc->debugfs.root,
emc, &tegra_emc_debug_available_rates_fops);
debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
emc, &tegra_emc_debug_min_rate_fops);
debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
emc, &tegra_emc_debug_max_rate_fops);
}
static int tegra_emc_probe(struct platform_device *pdev)
{
struct platform_device *mc;
struct device_node *np;
struct tegra_emc *emc;
int err;
if (of_get_child_count(pdev->dev.of_node) == 0) {
dev_info(&pdev->dev,
"device-tree node doesn't have memory timings\n");
return -ENODEV;
}
np = of_parse_phandle(pdev->dev.of_node, "nvidia,memory-controller", 0);
if (!np) {
dev_err(&pdev->dev, "could not get memory controller node\n");
return -ENOENT;
}
mc = of_find_device_by_node(np);
of_node_put(np);
if (!mc)
return -ENOENT;
np = 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->mc = platform_get_drvdata(mc);
if (!emc->mc)
return -EPROBE_DEFER;
init_completion(&emc->clk_handshake_complete);
emc->clk_nb.notifier_call = emc_clk_change_notify;
emc->dev = &pdev->dev;
err = emc_load_timings_from_dt(emc, np);
of_node_put(np);
if (err)
return err;
emc->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(emc->regs))
return PTR_ERR(emc->regs);
err = emc_setup_hw(emc);
if (err)
return err;
err = platform_get_irq(pdev, 0);
if (err < 0) {
dev_err(&pdev->dev, "interrupt not specified: %d\n", err);
return err;
}
emc->irq = err;
err = devm_request_irq(&pdev->dev, emc->irq, tegra_emc_isr, 0,
dev_name(&pdev->dev), emc);
if (err) {
dev_err(&pdev->dev, "failed to request irq: %d\n", 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 int tegra_emc_suspend(struct device *dev)
{
struct tegra_emc *emc = dev_get_drvdata(dev);
int err;
/* take exclusive control over the clock's rate */
err = clk_rate_exclusive_get(emc->clk);
if (err) {
dev_err(emc->dev, "failed to acquire clk: %d\n", err);
return err;
}
/* suspending in a bad state will hang machine */
if (WARN(emc->bad_state, "hardware in a bad state\n"))
return -EINVAL;
emc->bad_state = true;
return 0;
}
static int tegra_emc_resume(struct device *dev)
{
struct tegra_emc *emc = dev_get_drvdata(dev);
emc_setup_hw(emc);
emc->bad_state = false;
clk_rate_exclusive_put(emc->clk);
return 0;
}
static const struct dev_pm_ops tegra_emc_pm_ops = {
.suspend = tegra_emc_suspend,
.resume = tegra_emc_resume,
};
static const struct of_device_id tegra_emc_of_match[] = {
{ .compatible = "nvidia,tegra30-emc", },
{},
};
static struct platform_driver tegra_emc_driver = {
.probe = tegra_emc_probe,
.driver = {
.name = "tegra30-emc",
.of_match_table = tegra_emc_of_match,
.pm = &tegra_emc_pm_ops,
.suppress_bind_attrs = true,
},
};
static int __init tegra_emc_init(void)
{
return platform_driver_register(&tegra_emc_driver);
}
subsys_initcall(tegra_emc_init);