WIP FPC-III support

[linux/fpc-iii.git] / drivers / memory / tegra / tegra30-emc.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/debugfs.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interconnect-provider.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/types.h>

#include <soc/tegra/common.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;
};

enum emc_rate_request_type {
        EMC_RATE_DEBUG,
        EMC_RATE_ICC,
        EMC_RATE_TYPE_MAX,
};

struct emc_rate_request {
        unsigned long min_rate;
        unsigned long max_rate;
};

struct tegra_emc {
        struct device *dev;
        struct tegra_mc *mc;
        struct icc_provider provider;
        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;

        /*
         * There are multiple sources in the EMC driver which could request
         * a min/max clock rate, these rates are contained in this array.
         */
        struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX];

        /* protect shared rate-change code path */
        struct mutex rate_lock;
};

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 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 *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);

        return 0;
}

static int emc_complete_timing_change(struct tegra_emc *emc,
                                      unsigned long rate)
{
        struct emc_timing *timing = emc_find_timing(emc, rate);
        unsigned int dram_num;
        int err;
        u32 v;

        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;
        }

        /* 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)
                emc->bad_state = false;

        /* restore early ACK */
        mc_writel(emc->mc, emc->mc_override, MC_EMEM_ARB_OVERRIDE);

        return err;
}

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;

        if (of_get_child_count(dev->of_node) == 0) {
                dev_info(dev, "device-tree doesn't have memory timings\n");
                return NULL;
        }

        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;
        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;

        if (!emc->num_timings)
                return clk_get_rate(emc->clk);

        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;
}

static void tegra_emc_rate_requests_init(struct tegra_emc *emc)
{
        unsigned int i;

        for (i = 0; i < EMC_RATE_TYPE_MAX; i++) {
                emc->requested_rate[i].min_rate = 0;
                emc->requested_rate[i].max_rate = ULONG_MAX;
        }
}

static int emc_request_rate(struct tegra_emc *emc,
                            unsigned long new_min_rate,
                            unsigned long new_max_rate,
                            enum emc_rate_request_type type)
{
        struct emc_rate_request *req = emc->requested_rate;
        unsigned long min_rate = 0, max_rate = ULONG_MAX;
        unsigned int i;
        int err;

        /* select minimum and maximum rates among the requested rates */
        for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) {
                if (i == type) {
                        min_rate = max(new_min_rate, min_rate);
                        max_rate = min(new_max_rate, max_rate);
                } else {
                        min_rate = max(req->min_rate, min_rate);
                        max_rate = min(req->max_rate, max_rate);
                }
        }

        if (min_rate > max_rate) {
                dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n",
                                    __func__, type, min_rate, max_rate);
                return -ERANGE;
        }

        /*
         * EMC rate-changes should go via OPP API because it manages voltage
         * changes.
         */
        err = dev_pm_opp_set_rate(emc->dev, min_rate);
        if (err)
                return err;

        emc->requested_rate[type].min_rate = new_min_rate;
        emc->requested_rate[type].max_rate = new_max_rate;

        return 0;
}

static int emc_set_min_rate(struct tegra_emc *emc, unsigned long rate,
                            enum emc_rate_request_type type)
{
        struct emc_rate_request *req = &emc->requested_rate[type];
        int ret;

        mutex_lock(&emc->rate_lock);
        ret = emc_request_rate(emc, rate, req->max_rate, type);
        mutex_unlock(&emc->rate_lock);

        return ret;
}

static int emc_set_max_rate(struct tegra_emc *emc, unsigned long rate,
                            enum emc_rate_request_type type)
{
        struct emc_rate_request *req = &emc->requested_rate[type];
        int ret;

        mutex_lock(&emc->rate_lock);
        ret = emc_request_rate(emc, req->min_rate, rate, type);
        mutex_unlock(&emc->rate_lock);

        return ret;
}

/*
 * 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 = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG);
        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 = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG);
        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 inline struct tegra_emc *
to_tegra_emc_provider(struct icc_provider *provider)
{
        return container_of(provider, struct tegra_emc, provider);
}

static struct icc_node_data *
emc_of_icc_xlate_extended(struct of_phandle_args *spec, void *data)
{
        struct icc_provider *provider = data;
        struct icc_node_data *ndata;
        struct icc_node *node;

        /* External Memory is the only possible ICC route */
        list_for_each_entry(node, &provider->nodes, node_list) {
                if (node->id != TEGRA_ICC_EMEM)
                        continue;

                ndata = kzalloc(sizeof(*ndata), GFP_KERNEL);
                if (!ndata)
                        return ERR_PTR(-ENOMEM);

                /*
                 * SRC and DST nodes should have matching TAG in order to have
                 * it set by default for a requested path.
                 */
                ndata->tag = TEGRA_MC_ICC_TAG_ISO;
                ndata->node = node;

                return ndata;
        }

        return ERR_PTR(-EPROBE_DEFER);
}

static int emc_icc_set(struct icc_node *src, struct icc_node *dst)
{
        struct tegra_emc *emc = to_tegra_emc_provider(dst->provider);
        unsigned long long peak_bw = icc_units_to_bps(dst->peak_bw);
        unsigned long long avg_bw = icc_units_to_bps(dst->avg_bw);
        unsigned long long rate = max(avg_bw, peak_bw);
        const unsigned int dram_data_bus_width_bytes = 4;
        const unsigned int ddr = 2;
        int err;

        /*
         * Tegra30 EMC runs on a clock rate of SDRAM bus.  This means that
         * EMC clock rate is twice smaller than the peak data rate because
         * data is sampled on both EMC clock edges.
         */
        do_div(rate, ddr * dram_data_bus_width_bytes);
        rate = min_t(u64, rate, U32_MAX);

        err = emc_set_min_rate(emc, rate, EMC_RATE_ICC);
        if (err)
                return err;

        return 0;
}

static int tegra_emc_interconnect_init(struct tegra_emc *emc)
{
        const struct tegra_mc_soc *soc = emc->mc->soc;
        struct icc_node *node;
        int err;

        emc->provider.dev = emc->dev;
        emc->provider.set = emc_icc_set;
        emc->provider.data = &emc->provider;
        emc->provider.aggregate = soc->icc_ops->aggregate;
        emc->provider.xlate_extended = emc_of_icc_xlate_extended;

        err = icc_provider_add(&emc->provider);
        if (err)
                goto err_msg;

        /* create External Memory Controller node */
        node = icc_node_create(TEGRA_ICC_EMC);
        if (IS_ERR(node)) {
                err = PTR_ERR(node);
                goto del_provider;
        }

        node->name = "External Memory Controller";
        icc_node_add(node, &emc->provider);

        /* link External Memory Controller to External Memory (DRAM) */
        err = icc_link_create(node, TEGRA_ICC_EMEM);
        if (err)
                goto remove_nodes;

        /* create External Memory node */
        node = icc_node_create(TEGRA_ICC_EMEM);
        if (IS_ERR(node)) {
                err = PTR_ERR(node);
                goto remove_nodes;
        }

        node->name = "External Memory (DRAM)";
        icc_node_add(node, &emc->provider);

        return 0;

remove_nodes:
        icc_nodes_remove(&emc->provider);
del_provider:
        icc_provider_del(&emc->provider);
err_msg:
        dev_err(emc->dev, "failed to initialize ICC: %d\n", err);

        return err;
}

static int tegra_emc_opp_table_init(struct tegra_emc *emc)
{
        u32 hw_version = BIT(tegra_sku_info.soc_speedo_id);
        struct opp_table *clk_opp_table, *hw_opp_table;
        int err;

        clk_opp_table = dev_pm_opp_set_clkname(emc->dev, NULL);
        err = PTR_ERR_OR_ZERO(clk_opp_table);
        if (err) {
                dev_err(emc->dev, "failed to set OPP clk: %d\n", err);
                return err;
        }

        hw_opp_table = dev_pm_opp_set_supported_hw(emc->dev, &hw_version, 1);
        err = PTR_ERR_OR_ZERO(hw_opp_table);
        if (err) {
                dev_err(emc->dev, "failed to set OPP supported HW: %d\n", err);
                goto put_clk_table;
        }

        err = dev_pm_opp_of_add_table(emc->dev);
        if (err) {
                if (err == -ENODEV)
                        dev_err(emc->dev, "OPP table not found, please update your device tree\n");
                else
                        dev_err(emc->dev, "failed to add OPP table: %d\n", err);

                goto put_hw_table;
        }

        dev_info(emc->dev, "OPP HW ver. 0x%x, current clock rate %lu MHz\n",
                 hw_version, clk_get_rate(emc->clk) / 1000000);

        /* first dummy rate-set initializes voltage state */
        err = dev_pm_opp_set_rate(emc->dev, clk_get_rate(emc->clk));
        if (err) {
                dev_err(emc->dev, "failed to initialize OPP clock: %d\n", err);
                goto remove_table;
        }

        return 0;

remove_table:
        dev_pm_opp_of_remove_table(emc->dev);
put_hw_table:
        dev_pm_opp_put_supported_hw(hw_opp_table);
put_clk_table:
        dev_pm_opp_put_clkname(clk_opp_table);

        return err;
}

static void devm_tegra_emc_unset_callback(void *data)
{
        tegra20_clk_set_emc_round_callback(NULL, NULL);
}

static void devm_tegra_emc_unreg_clk_notifier(void *data)
{
        struct tegra_emc *emc = data;

        clk_notifier_unregister(emc->clk, &emc->clk_nb);
}

static int tegra_emc_init_clk(struct tegra_emc *emc)
{
        int err;

        tegra20_clk_set_emc_round_callback(emc_round_rate, emc);

        err = devm_add_action_or_reset(emc->dev, devm_tegra_emc_unset_callback,
                                       NULL);
        if (err)
                return err;

        emc->clk = devm_clk_get(emc->dev, NULL);
        if (IS_ERR(emc->clk)) {
                dev_err(emc->dev, "failed to get EMC clock: %pe\n", emc->clk);
                return PTR_ERR(emc->clk);
        }

        err = clk_notifier_register(emc->clk, &emc->clk_nb);
        if (err) {
                dev_err(emc->dev, "failed to register clk notifier: %d\n", err);
                return err;
        }

        err = devm_add_action_or_reset(emc->dev,
                                       devm_tegra_emc_unreg_clk_notifier, emc);
        if (err)
                return err;

        return 0;
}

static int tegra_emc_probe(struct platform_device *pdev)
{
        struct device_node *np;
        struct tegra_emc *emc;
        int err;

        emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
        if (!emc)
                return -ENOMEM;

        emc->mc = devm_tegra_memory_controller_get(&pdev->dev);
        if (IS_ERR(emc->mc))
                return PTR_ERR(emc->mc);

        mutex_init(&emc->rate_lock);
        emc->clk_nb.notifier_call = emc_clk_change_notify;
        emc->dev = &pdev->dev;

        np = emc_find_node_by_ram_code(&pdev->dev);
        if (np) {
                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)
                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;
        }

        err = tegra_emc_init_clk(emc);
        if (err)
                return err;

        err = tegra_emc_opp_table_init(emc);
        if (err)
                return err;

        platform_set_drvdata(pdev, emc);
        tegra_emc_rate_requests_init(emc);
        tegra_emc_debugfs_init(emc);
        tegra_emc_interconnect_init(emc);

        /*
         * Don't allow the kernel module to be unloaded. Unloading adds some
         * extra complexity which doesn't really worth the effort in a case of
         * this driver.
         */
        try_module_get(THIS_MODULE);

        return 0;
}

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", },
        {},
};
MODULE_DEVICE_TABLE(of, tegra_emc_of_match);

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,
                .sync_state = icc_sync_state,
        },
};
module_platform_driver(tegra_emc_driver);

MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
MODULE_DESCRIPTION("NVIDIA Tegra30 EMC driver");
MODULE_LICENSE("GPL v2");