Merge remote-tracking branch 'h8300/h8300-next'

[karo-tx-linux.git] / drivers / clk / tegra / clk-dfll.c

/*
 * clk-dfll.c - Tegra DFLL clock source common code
 *
 * Copyright (C) 2012-2014 NVIDIA Corporation. All rights reserved.
 *
 * Aleksandr Frid <afrid@nvidia.com>
 * Paul Walmsley <pwalmsley@nvidia.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * This library is for the DVCO and DFLL IP blocks on the Tegra124
 * SoC. These IP blocks together are also known at NVIDIA as
 * "CL-DVFS". To try to avoid confusion, this code refers to them
 * collectively as the "DFLL."
 *
 * The DFLL is a root clocksource which tolerates some amount of
 * supply voltage noise. Tegra124 uses it to clock the fast CPU
 * complex when the target CPU speed is above a particular rate. The
 * DFLL can be operated in either open-loop mode or closed-loop mode.
 * In open-loop mode, the DFLL generates an output clock appropriate
 * to the supply voltage. In closed-loop mode, when configured with a
 * target frequency, the DFLL minimizes supply voltage while
 * delivering an average frequency equal to the target.
 *
 * Devices clocked by the DFLL must be able to tolerate frequency
 * variation. In the case of the CPU, it's important to note that the
 * CPU cycle time will vary. This has implications for
 * performance-measurement code and any code that relies on the CPU
 * cycle time to delay for a certain length of time.
 *
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm_opp.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/reset.h>
#include <linux/seq_file.h>

#include "clk-dfll.h"

/*
 * DFLL control registers - access via dfll_{readl,writel}
 */

/* DFLL_CTRL: DFLL control register */
#define DFLL_CTRL                       0x00
#define DFLL_CTRL_MODE_MASK             0x03

/* DFLL_CONFIG: DFLL sample rate control */
#define DFLL_CONFIG                     0x04
#define DFLL_CONFIG_DIV_MASK            0xff
#define DFLL_CONFIG_DIV_PRESCALE        32

/* DFLL_PARAMS: tuning coefficients for closed loop integrator */
#define DFLL_PARAMS                     0x08
#define DFLL_PARAMS_CG_SCALE            (0x1 << 24)
#define DFLL_PARAMS_FORCE_MODE_SHIFT    22
#define DFLL_PARAMS_FORCE_MODE_MASK     (0x3 << DFLL_PARAMS_FORCE_MODE_SHIFT)
#define DFLL_PARAMS_CF_PARAM_SHIFT      16
#define DFLL_PARAMS_CF_PARAM_MASK       (0x3f << DFLL_PARAMS_CF_PARAM_SHIFT)
#define DFLL_PARAMS_CI_PARAM_SHIFT      8
#define DFLL_PARAMS_CI_PARAM_MASK       (0x7 << DFLL_PARAMS_CI_PARAM_SHIFT)
#define DFLL_PARAMS_CG_PARAM_SHIFT      0
#define DFLL_PARAMS_CG_PARAM_MASK       (0xff << DFLL_PARAMS_CG_PARAM_SHIFT)

/* DFLL_TUNE0: delay line configuration register 0 */
#define DFLL_TUNE0                      0x0c

/* DFLL_TUNE1: delay line configuration register 1 */
#define DFLL_TUNE1                      0x10

/* DFLL_FREQ_REQ: target DFLL frequency control */
#define DFLL_FREQ_REQ                   0x14
#define DFLL_FREQ_REQ_FORCE_ENABLE      (0x1 << 28)
#define DFLL_FREQ_REQ_FORCE_SHIFT       16
#define DFLL_FREQ_REQ_FORCE_MASK        (0xfff << DFLL_FREQ_REQ_FORCE_SHIFT)
#define FORCE_MAX                       2047
#define FORCE_MIN                       -2048
#define DFLL_FREQ_REQ_SCALE_SHIFT       8
#define DFLL_FREQ_REQ_SCALE_MASK        (0xff << DFLL_FREQ_REQ_SCALE_SHIFT)
#define DFLL_FREQ_REQ_SCALE_MAX         256
#define DFLL_FREQ_REQ_FREQ_VALID        (0x1 << 7)
#define DFLL_FREQ_REQ_MULT_SHIFT        0
#define DFLL_FREQ_REG_MULT_MASK         (0x7f << DFLL_FREQ_REQ_MULT_SHIFT)
#define FREQ_MAX                        127

/* DFLL_DROOP_CTRL: droop prevention control */
#define DFLL_DROOP_CTRL                 0x1c

/* DFLL_OUTPUT_CFG: closed loop mode control registers */
/* NOTE: access via dfll_i2c_{readl,writel} */
#define DFLL_OUTPUT_CFG                 0x20
#define DFLL_OUTPUT_CFG_I2C_ENABLE      (0x1 << 30)
#define OUT_MASK                        0x3f
#define DFLL_OUTPUT_CFG_SAFE_SHIFT      24
#define DFLL_OUTPUT_CFG_SAFE_MASK       \
                (OUT_MASK << DFLL_OUTPUT_CFG_SAFE_SHIFT)
#define DFLL_OUTPUT_CFG_MAX_SHIFT       16
#define DFLL_OUTPUT_CFG_MAX_MASK        \
                (OUT_MASK << DFLL_OUTPUT_CFG_MAX_SHIFT)
#define DFLL_OUTPUT_CFG_MIN_SHIFT       8
#define DFLL_OUTPUT_CFG_MIN_MASK        \
                (OUT_MASK << DFLL_OUTPUT_CFG_MIN_SHIFT)
#define DFLL_OUTPUT_CFG_PWM_DELTA       (0x1 << 7)
#define DFLL_OUTPUT_CFG_PWM_ENABLE      (0x1 << 6)
#define DFLL_OUTPUT_CFG_PWM_DIV_SHIFT   0
#define DFLL_OUTPUT_CFG_PWM_DIV_MASK    \
                (OUT_MASK << DFLL_OUTPUT_CFG_PWM_DIV_SHIFT)

/* DFLL_OUTPUT_FORCE: closed loop mode voltage forcing control */
#define DFLL_OUTPUT_FORCE               0x24
#define DFLL_OUTPUT_FORCE_ENABLE        (0x1 << 6)
#define DFLL_OUTPUT_FORCE_VALUE_SHIFT   0
#define DFLL_OUTPUT_FORCE_VALUE_MASK    \
                (OUT_MASK << DFLL_OUTPUT_FORCE_VALUE_SHIFT)

/* DFLL_MONITOR_CTRL: internal monitor data source control */
#define DFLL_MONITOR_CTRL               0x28
#define DFLL_MONITOR_CTRL_FREQ          6

/* DFLL_MONITOR_DATA: internal monitor data output */
#define DFLL_MONITOR_DATA               0x2c
#define DFLL_MONITOR_DATA_NEW_MASK      (0x1 << 16)
#define DFLL_MONITOR_DATA_VAL_SHIFT     0
#define DFLL_MONITOR_DATA_VAL_MASK      (0xFFFF << DFLL_MONITOR_DATA_VAL_SHIFT)

/*
 * I2C output control registers - access via dfll_i2c_{readl,writel}
 */

/* DFLL_I2C_CFG: I2C controller configuration register */
#define DFLL_I2C_CFG                    0x40
#define DFLL_I2C_CFG_ARB_ENABLE         (0x1 << 20)
#define DFLL_I2C_CFG_HS_CODE_SHIFT      16
#define DFLL_I2C_CFG_HS_CODE_MASK       (0x7 << DFLL_I2C_CFG_HS_CODE_SHIFT)
#define DFLL_I2C_CFG_PACKET_ENABLE      (0x1 << 15)
#define DFLL_I2C_CFG_SIZE_SHIFT         12
#define DFLL_I2C_CFG_SIZE_MASK          (0x7 << DFLL_I2C_CFG_SIZE_SHIFT)
#define DFLL_I2C_CFG_SLAVE_ADDR_10      (0x1 << 10)
#define DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_7BIT      1
#define DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_10BIT     0

/* DFLL_I2C_VDD_REG_ADDR: PMIC I2C address for closed loop mode */
#define DFLL_I2C_VDD_REG_ADDR           0x44

/* DFLL_I2C_STS: I2C controller status */
#define DFLL_I2C_STS                    0x48
#define DFLL_I2C_STS_I2C_LAST_SHIFT     1
#define DFLL_I2C_STS_I2C_REQ_PENDING    0x1

/* DFLL_INTR_STS: DFLL interrupt status register */
#define DFLL_INTR_STS                   0x5c

/* DFLL_INTR_EN: DFLL interrupt enable register */
#define DFLL_INTR_EN                    0x60
#define DFLL_INTR_MIN_MASK              0x1
#define DFLL_INTR_MAX_MASK              0x2

/*
 * Integrated I2C controller registers - relative to td->i2c_controller_base
 */

/* DFLL_I2C_CLK_DIVISOR: I2C controller clock divisor */
#define DFLL_I2C_CLK_DIVISOR            0x6c
#define DFLL_I2C_CLK_DIVISOR_MASK       0xffff
#define DFLL_I2C_CLK_DIVISOR_FS_SHIFT   16
#define DFLL_I2C_CLK_DIVISOR_HS_SHIFT   0
#define DFLL_I2C_CLK_DIVISOR_PREDIV     8
#define DFLL_I2C_CLK_DIVISOR_HSMODE_PREDIV      12

/*
 * Other constants
 */

/* MAX_DFLL_VOLTAGES: number of LUT entries in the DFLL IP block */
#define MAX_DFLL_VOLTAGES               33

/*
 * REF_CLK_CYC_PER_DVCO_SAMPLE: the number of ref_clk cycles that the hardware
 *    integrates the DVCO counter over - used for debug rate monitoring and
 *    droop control
 */
#define REF_CLK_CYC_PER_DVCO_SAMPLE     4

/*
 * REF_CLOCK_RATE: the DFLL reference clock rate currently supported by this
 * driver, in Hz
 */
#define REF_CLOCK_RATE                  51000000UL

#define DVCO_RATE_TO_MULT(rate, ref_rate)       ((rate) / ((ref_rate) / 2))
#define MULT_TO_DVCO_RATE(mult, ref_rate)       ((mult) * ((ref_rate) / 2))

/**
 * enum dfll_ctrl_mode - DFLL hardware operating mode
 * @DFLL_UNINITIALIZED: (uninitialized state - not in hardware bitfield)
 * @DFLL_DISABLED: DFLL not generating an output clock
 * @DFLL_OPEN_LOOP: DVCO running, but DFLL not adjusting voltage
 * @DFLL_CLOSED_LOOP: DVCO running, and DFLL adjusting voltage to match
 *                    the requested rate
 *
 * The integer corresponding to the last two states, minus one, is
 * written to the DFLL hardware to change operating modes.
 */
enum dfll_ctrl_mode {
        DFLL_UNINITIALIZED = 0,
        DFLL_DISABLED = 1,
        DFLL_OPEN_LOOP = 2,
        DFLL_CLOSED_LOOP = 3,
};

/**
 * enum dfll_tune_range - voltage range that the driver believes it's in
 * @DFLL_TUNE_UNINITIALIZED: DFLL tuning not yet programmed
 * @DFLL_TUNE_LOW: DFLL in the low-voltage range (or open-loop mode)
 *
 * Some DFLL tuning parameters may need to change depending on the
 * DVCO's voltage; these states represent the ranges that the driver
 * supports. These are software states; these values are never
 * written into registers.
 */
enum dfll_tune_range {
        DFLL_TUNE_UNINITIALIZED = 0,
        DFLL_TUNE_LOW = 1,
};

/**
 * struct dfll_rate_req - target DFLL rate request data
 * @rate: target frequency, after the postscaling
 * @dvco_target_rate: target frequency, after the postscaling
 * @lut_index: LUT index at which voltage the dvco_target_rate will be reached
 * @mult_bits: value to program to the MULT bits of the DFLL_FREQ_REQ register
 * @scale_bits: value to program to the SCALE bits of the DFLL_FREQ_REQ register
 */
struct dfll_rate_req {
        unsigned long rate;
        unsigned long dvco_target_rate;
        int lut_index;
        u8 mult_bits;
        u8 scale_bits;
};

struct tegra_dfll {
        struct device                   *dev;
        struct tegra_dfll_soc_data      *soc;

        void __iomem                    *base;
        void __iomem                    *i2c_base;
        void __iomem                    *i2c_controller_base;
        void __iomem                    *lut_base;

        struct regulator                *vdd_reg;
        struct clk                      *soc_clk;
        struct clk                      *ref_clk;
        struct clk                      *i2c_clk;
        struct clk                      *dfll_clk;
        struct reset_control            *dvco_rst;
        unsigned long                   ref_rate;
        unsigned long                   i2c_clk_rate;
        unsigned long                   dvco_rate_min;

        enum dfll_ctrl_mode             mode;
        enum dfll_tune_range            tune_range;
        struct dentry                   *debugfs_dir;
        struct clk_hw                   dfll_clk_hw;
        const char                      *output_clock_name;
        struct dfll_rate_req            last_req;
        unsigned long                   last_unrounded_rate;

        /* Parameters from DT */
        u32                             droop_ctrl;
        u32                             sample_rate;
        u32                             force_mode;
        u32                             cf;
        u32                             ci;
        u32                             cg;
        bool                            cg_scale;

        /* I2C interface parameters */
        u32                             i2c_fs_rate;
        u32                             i2c_reg;
        u32                             i2c_slave_addr;

        /* i2c_lut array entries are regulator framework selectors */
        unsigned                        i2c_lut[MAX_DFLL_VOLTAGES];
        int                             i2c_lut_size;
        u8                              lut_min, lut_max, lut_safe;
};

#define clk_hw_to_dfll(_hw) container_of(_hw, struct tegra_dfll, dfll_clk_hw)

/* mode_name: map numeric DFLL modes to names for friendly console messages */
static const char * const mode_name[] = {
        [DFLL_UNINITIALIZED] = "uninitialized",
        [DFLL_DISABLED] = "disabled",
        [DFLL_OPEN_LOOP] = "open_loop",
        [DFLL_CLOSED_LOOP] = "closed_loop",
};

/*
 * Register accessors
 */

static inline u32 dfll_readl(struct tegra_dfll *td, u32 offs)
{
        return __raw_readl(td->base + offs);
}

static inline void dfll_writel(struct tegra_dfll *td, u32 val, u32 offs)
{
        WARN_ON(offs >= DFLL_I2C_CFG);
        __raw_writel(val, td->base + offs);
}

static inline void dfll_wmb(struct tegra_dfll *td)
{
        dfll_readl(td, DFLL_CTRL);
}

/* I2C output control registers - for addresses above DFLL_I2C_CFG */

static inline u32 dfll_i2c_readl(struct tegra_dfll *td, u32 offs)
{
        return __raw_readl(td->i2c_base + offs);
}

static inline void dfll_i2c_writel(struct tegra_dfll *td, u32 val, u32 offs)
{
        __raw_writel(val, td->i2c_base + offs);
}

static inline void dfll_i2c_wmb(struct tegra_dfll *td)
{
        dfll_i2c_readl(td, DFLL_I2C_CFG);
}

/**
 * dfll_is_running - is the DFLL currently generating a clock?
 * @td: DFLL instance
 *
 * If the DFLL is currently generating an output clock signal, return
 * true; otherwise return false.
 */
static bool dfll_is_running(struct tegra_dfll *td)
{
        return td->mode >= DFLL_OPEN_LOOP;
}

/*
 * Runtime PM suspend/resume callbacks
 */

/**
 * tegra_dfll_runtime_resume - enable all clocks needed by the DFLL
 * @dev: DFLL device *
 *
 * Enable all clocks needed by the DFLL. Assumes that clk_prepare()
 * has already been called on all the clocks.
 *
 * XXX Should also handle context restore when returning from off.
 */
int tegra_dfll_runtime_resume(struct device *dev)
{
        struct tegra_dfll *td = dev_get_drvdata(dev);
        int ret;

        ret = clk_enable(td->ref_clk);
        if (ret) {
                dev_err(dev, "could not enable ref clock: %d\n", ret);
                return ret;
        }

        ret = clk_enable(td->soc_clk);
        if (ret) {
                dev_err(dev, "could not enable register clock: %d\n", ret);
                clk_disable(td->ref_clk);
                return ret;
        }

        ret = clk_enable(td->i2c_clk);
        if (ret) {
                dev_err(dev, "could not enable i2c clock: %d\n", ret);
                clk_disable(td->soc_clk);
                clk_disable(td->ref_clk);
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL(tegra_dfll_runtime_resume);

/**
 * tegra_dfll_runtime_suspend - disable all clocks needed by the DFLL
 * @dev: DFLL device *
 *
 * Disable all clocks needed by the DFLL. Assumes that other code
 * will later call clk_unprepare().
 */
int tegra_dfll_runtime_suspend(struct device *dev)
{
        struct tegra_dfll *td = dev_get_drvdata(dev);

        clk_disable(td->ref_clk);
        clk_disable(td->soc_clk);
        clk_disable(td->i2c_clk);

        return 0;
}
EXPORT_SYMBOL(tegra_dfll_runtime_suspend);

/*
 * DFLL tuning operations (per-voltage-range tuning settings)
 */

/**
 * dfll_tune_low - tune to DFLL and CPU settings valid for any voltage
 * @td: DFLL instance
 *
 * Tune the DFLL oscillator parameters and the CPU clock shaper for
 * the low-voltage range. These settings are valid for any voltage,
 * but may not be optimal.
 */
static void dfll_tune_low(struct tegra_dfll *td)
{
        td->tune_range = DFLL_TUNE_LOW;

        dfll_writel(td, td->soc->tune0_low, DFLL_TUNE0);
        dfll_writel(td, td->soc->tune1, DFLL_TUNE1);
        dfll_wmb(td);

        if (td->soc->set_clock_trimmers_low)
                td->soc->set_clock_trimmers_low();
}

/*
 * Output clock scaler helpers
 */

/**
 * dfll_scale_dvco_rate - calculate scaled rate from the DVCO rate
 * @scale_bits: clock scaler value (bits in the DFLL_FREQ_REQ_SCALE field)
 * @dvco_rate: the DVCO rate
 *
 * Apply the same scaling formula that the DFLL hardware uses to scale
 * the DVCO rate.
 */
static unsigned long dfll_scale_dvco_rate(int scale_bits,
                                          unsigned long dvco_rate)
{
        return (u64)dvco_rate * (scale_bits + 1) / DFLL_FREQ_REQ_SCALE_MAX;
}

/*
 * DFLL mode switching
 */

/**
 * dfll_set_mode - change the DFLL control mode
 * @td: DFLL instance
 * @mode: DFLL control mode (see enum dfll_ctrl_mode)
 *
 * Change the DFLL's operating mode between disabled, open-loop mode,
 * and closed-loop mode, or vice versa.
 */
static void dfll_set_mode(struct tegra_dfll *td,
                          enum dfll_ctrl_mode mode)
{
        td->mode = mode;
        dfll_writel(td, mode - 1, DFLL_CTRL);
        dfll_wmb(td);
}

/*
 * DFLL-to-I2C controller interface
 */

/**
 * dfll_i2c_set_output_enabled - enable/disable I2C PMIC voltage requests
 * @td: DFLL instance
 * @enable: whether to enable or disable the I2C voltage requests
 *
 * Set the master enable control for I2C control value updates. If disabled,
 * then I2C control messages are inhibited, regardless of the DFLL mode.
 */
static int dfll_i2c_set_output_enabled(struct tegra_dfll *td, bool enable)
{
        u32 val;

        val = dfll_i2c_readl(td, DFLL_OUTPUT_CFG);

        if (enable)
                val |= DFLL_OUTPUT_CFG_I2C_ENABLE;
        else
                val &= ~DFLL_OUTPUT_CFG_I2C_ENABLE;

        dfll_i2c_writel(td, val, DFLL_OUTPUT_CFG);
        dfll_i2c_wmb(td);

        return 0;
}

/**
 * dfll_load_lut - load the voltage lookup table
 * @td: struct tegra_dfll *
 *
 * Load the voltage-to-PMIC register value lookup table into the DFLL
 * IP block memory. Look-up tables can be loaded at any time.
 */
static void dfll_load_i2c_lut(struct tegra_dfll *td)
{
        int i, lut_index;
        u32 val;

        for (i = 0; i < MAX_DFLL_VOLTAGES; i++) {
                if (i < td->lut_min)
                        lut_index = td->lut_min;
                else if (i > td->lut_max)
                        lut_index = td->lut_max;
                else
                        lut_index = i;

                val = regulator_list_hardware_vsel(td->vdd_reg,
                                                     td->i2c_lut[lut_index]);
                __raw_writel(val, td->lut_base + i * 4);
        }

        dfll_i2c_wmb(td);
}

/**
 * dfll_init_i2c_if - set up the DFLL's DFLL-I2C interface
 * @td: DFLL instance
 *
 * During DFLL driver initialization, program the DFLL-I2C interface
 * with the PMU slave address, vdd register offset, and transfer mode.
 * This data is used by the DFLL to automatically construct I2C
 * voltage-set commands, which are then passed to the DFLL's internal
 * I2C controller.
 */
static void dfll_init_i2c_if(struct tegra_dfll *td)
{
        u32 val;

        if (td->i2c_slave_addr > 0x7f) {
                val = td->i2c_slave_addr << DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_10BIT;
                val |= DFLL_I2C_CFG_SLAVE_ADDR_10;
        } else {
                val = td->i2c_slave_addr << DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_7BIT;
        }
        val |= DFLL_I2C_CFG_SIZE_MASK;
        val |= DFLL_I2C_CFG_ARB_ENABLE;
        dfll_i2c_writel(td, val, DFLL_I2C_CFG);

        dfll_i2c_writel(td, td->i2c_reg, DFLL_I2C_VDD_REG_ADDR);

        val = DIV_ROUND_UP(td->i2c_clk_rate, td->i2c_fs_rate * 8);
        BUG_ON(!val || (val > DFLL_I2C_CLK_DIVISOR_MASK));
        val = (val - 1) << DFLL_I2C_CLK_DIVISOR_FS_SHIFT;

        /* default hs divisor just in case */
        val |= 1 << DFLL_I2C_CLK_DIVISOR_HS_SHIFT;
        __raw_writel(val, td->i2c_controller_base + DFLL_I2C_CLK_DIVISOR);
        dfll_i2c_wmb(td);
}

/**
 * dfll_init_out_if - prepare DFLL-to-PMIC interface
 * @td: DFLL instance
 *
 * During DFLL driver initialization or resume from context loss,
 * disable the I2C command output to the PMIC, set safe voltage and
 * output limits, and disable and clear limit interrupts.
 */
static void dfll_init_out_if(struct tegra_dfll *td)
{
        u32 val;

        td->lut_min = 0;
        td->lut_max = td->i2c_lut_size - 1;
        td->lut_safe = td->lut_min + 1;

        dfll_i2c_writel(td, 0, DFLL_OUTPUT_CFG);
        val = (td->lut_safe << DFLL_OUTPUT_CFG_SAFE_SHIFT) |
                (td->lut_max << DFLL_OUTPUT_CFG_MAX_SHIFT) |
                (td->lut_min << DFLL_OUTPUT_CFG_MIN_SHIFT);
        dfll_i2c_writel(td, val, DFLL_OUTPUT_CFG);
        dfll_i2c_wmb(td);

        dfll_writel(td, 0, DFLL_OUTPUT_FORCE);
        dfll_i2c_writel(td, 0, DFLL_INTR_EN);
        dfll_i2c_writel(td, DFLL_INTR_MAX_MASK | DFLL_INTR_MIN_MASK,
                        DFLL_INTR_STS);

        dfll_load_i2c_lut(td);
        dfll_init_i2c_if(td);
}

/*
 * Set/get the DFLL's targeted output clock rate
 */

/**
 * find_lut_index_for_rate - determine I2C LUT index for given DFLL rate
 * @td: DFLL instance
 * @rate: clock rate
 *
 * Determines the index of a I2C LUT entry for a voltage that approximately
 * produces the given DFLL clock rate. This is used when forcing a value
 * to the integrator during rate changes. Returns -ENOENT if a suitable
 * LUT index is not found.
 */
static int find_lut_index_for_rate(struct tegra_dfll *td, unsigned long rate)
{
        struct dev_pm_opp *opp;
        int i, uv;

        rcu_read_lock();

        opp = dev_pm_opp_find_freq_ceil(td->soc->dev, &rate);
        if (IS_ERR(opp)) {
                rcu_read_unlock();
                return PTR_ERR(opp);
        }
        uv = dev_pm_opp_get_voltage(opp);

        rcu_read_unlock();

        for (i = 0; i < td->i2c_lut_size; i++) {
                if (regulator_list_voltage(td->vdd_reg, td->i2c_lut[i]) == uv)
                        return i;
        }

        return -ENOENT;
}

/**
 * dfll_calculate_rate_request - calculate DFLL parameters for a given rate
 * @td: DFLL instance
 * @req: DFLL-rate-request structure
 * @rate: the desired DFLL rate
 *
 * Populate the DFLL-rate-request record @req fields with the scale_bits
 * and mult_bits fields, based on the target input rate. Returns 0 upon
 * success, or -EINVAL if the requested rate in req->rate is too high
 * or low for the DFLL to generate.
 */
static int dfll_calculate_rate_request(struct tegra_dfll *td,
                                       struct dfll_rate_req *req,
                                       unsigned long rate)
{
        u32 val;

        /*
         * If requested rate is below the minimum DVCO rate, active the scaler.
         * In the future the DVCO minimum voltage should be selected based on
         * chip temperature and the actual minimum rate should be calibrated
         * at runtime.
         */
        req->scale_bits = DFLL_FREQ_REQ_SCALE_MAX - 1;
        if (rate < td->dvco_rate_min) {
                int scale;

                scale = DIV_ROUND_CLOSEST(rate / 1000 * DFLL_FREQ_REQ_SCALE_MAX,
                                          td->dvco_rate_min / 1000);
                if (!scale) {
                        dev_err(td->dev, "%s: Rate %lu is too low\n",
                                __func__, rate);
                        return -EINVAL;
                }
                req->scale_bits = scale - 1;
                rate = td->dvco_rate_min;
        }

        /* Convert requested rate into frequency request and scale settings */
        val = DVCO_RATE_TO_MULT(rate, td->ref_rate);
        if (val > FREQ_MAX) {
                dev_err(td->dev, "%s: Rate %lu is above dfll range\n",
                        __func__, rate);
                return -EINVAL;
        }
        req->mult_bits = val;
        req->dvco_target_rate = MULT_TO_DVCO_RATE(req->mult_bits, td->ref_rate);
        req->rate = dfll_scale_dvco_rate(req->scale_bits,
                                         req->dvco_target_rate);
        req->lut_index = find_lut_index_for_rate(td, req->dvco_target_rate);
        if (req->lut_index < 0)
                return req->lut_index;

        return 0;
}

/**
 * dfll_set_frequency_request - start the frequency change operation
 * @td: DFLL instance
 * @req: rate request structure
 *
 * Tell the DFLL to try to change its output frequency to the
 * frequency represented by @req. DFLL must be in closed-loop mode.
 */
static void dfll_set_frequency_request(struct tegra_dfll *td,
                                       struct dfll_rate_req *req)
{
        u32 val = 0;
        int force_val;
        int coef = 128; /* FIXME: td->cg_scale? */;

        force_val = (req->lut_index - td->lut_safe) * coef / td->cg;
        force_val = clamp(force_val, FORCE_MIN, FORCE_MAX);

        val |= req->mult_bits << DFLL_FREQ_REQ_MULT_SHIFT;
        val |= req->scale_bits << DFLL_FREQ_REQ_SCALE_SHIFT;
        val |= ((u32)force_val << DFLL_FREQ_REQ_FORCE_SHIFT) &
                DFLL_FREQ_REQ_FORCE_MASK;
        val |= DFLL_FREQ_REQ_FREQ_VALID | DFLL_FREQ_REQ_FORCE_ENABLE;

        dfll_writel(td, val, DFLL_FREQ_REQ);
        dfll_wmb(td);
}

/**
 * tegra_dfll_request_rate - set the next rate for the DFLL to tune to
 * @td: DFLL instance
 * @rate: clock rate to target
 *
 * Convert the requested clock rate @rate into the DFLL control logic
 * settings. In closed-loop mode, update new settings immediately to
 * adjust DFLL output rate accordingly. Otherwise, just save them
 * until the next switch to closed loop. Returns 0 upon success,
 * -EPERM if the DFLL driver has not yet been initialized, or -EINVAL
 * if @rate is outside the DFLL's tunable range.
 */
static int dfll_request_rate(struct tegra_dfll *td, unsigned long rate)
{
        int ret;
        struct dfll_rate_req req;

        if (td->mode == DFLL_UNINITIALIZED) {
                dev_err(td->dev, "%s: Cannot set DFLL rate in %s mode\n",
                        __func__, mode_name[td->mode]);
                return -EPERM;
        }

        ret = dfll_calculate_rate_request(td, &req, rate);
        if (ret)
                return ret;

        td->last_unrounded_rate = rate;
        td->last_req = req;

        if (td->mode == DFLL_CLOSED_LOOP)
                dfll_set_frequency_request(td, &td->last_req);

        return 0;
}

/*
 * DFLL enable/disable & open-loop <-> closed-loop transitions
 */

/**
 * dfll_disable - switch from open-loop mode to disabled mode
 * @td: DFLL instance
 *
 * Switch from OPEN_LOOP state to DISABLED state. Returns 0 upon success
 * or -EPERM if the DFLL is not currently in open-loop mode.
 */
static int dfll_disable(struct tegra_dfll *td)
{
        if (td->mode != DFLL_OPEN_LOOP) {
                dev_err(td->dev, "cannot disable DFLL in %s mode\n",
                        mode_name[td->mode]);
                return -EINVAL;
        }

        dfll_set_mode(td, DFLL_DISABLED);
        pm_runtime_put_sync(td->dev);

        return 0;
}

/**
 * dfll_enable - switch a disabled DFLL to open-loop mode
 * @td: DFLL instance
 *
 * Switch from DISABLED state to OPEN_LOOP state. Returns 0 upon success
 * or -EPERM if the DFLL is not currently disabled.
 */
static int dfll_enable(struct tegra_dfll *td)
{
        if (td->mode != DFLL_DISABLED) {
                dev_err(td->dev, "cannot enable DFLL in %s mode\n",
                        mode_name[td->mode]);
                return -EPERM;
        }

        pm_runtime_get_sync(td->dev);
        dfll_set_mode(td, DFLL_OPEN_LOOP);

        return 0;
}

/**
 * dfll_set_open_loop_config - prepare to switch to open-loop mode
 * @td: DFLL instance
 *
 * Prepare to switch the DFLL to open-loop mode. This switches the
 * DFLL to the low-voltage tuning range, ensures that I2C output
 * forcing is disabled, and disables the output clock rate scaler.
 * The DFLL's low-voltage tuning range parameters must be
 * characterized to keep the downstream device stable at any DVCO
 * input voltage. No return value.
 */
static void dfll_set_open_loop_config(struct tegra_dfll *td)
{
        u32 val;

        /* always tune low (safe) in open loop */
        if (td->tune_range != DFLL_TUNE_LOW)
                dfll_tune_low(td);

        val = dfll_readl(td, DFLL_FREQ_REQ);
        val |= DFLL_FREQ_REQ_SCALE_MASK;
        val &= ~DFLL_FREQ_REQ_FORCE_ENABLE;
        dfll_writel(td, val, DFLL_FREQ_REQ);
        dfll_wmb(td);
}

/**
 * tegra_dfll_lock - switch from open-loop to closed-loop mode
 * @td: DFLL instance
 *
 * Switch from OPEN_LOOP state to CLOSED_LOOP state. Returns 0 upon success,
 * -EINVAL if the DFLL's target rate hasn't been set yet, or -EPERM if the
 * DFLL is not currently in open-loop mode.
 */
static int dfll_lock(struct tegra_dfll *td)
{
        struct dfll_rate_req *req = &td->last_req;

        switch (td->mode) {
        case DFLL_CLOSED_LOOP:
                return 0;

        case DFLL_OPEN_LOOP:
                if (req->rate == 0) {
                        dev_err(td->dev, "%s: Cannot lock DFLL at rate 0\n",
                                __func__);
                        return -EINVAL;
                }

                dfll_i2c_set_output_enabled(td, true);
                dfll_set_mode(td, DFLL_CLOSED_LOOP);
                dfll_set_frequency_request(td, req);
                return 0;

        default:
                BUG_ON(td->mode > DFLL_CLOSED_LOOP);
                dev_err(td->dev, "%s: Cannot lock DFLL in %s mode\n",
                        __func__, mode_name[td->mode]);
                return -EPERM;
        }
}

/**
 * tegra_dfll_unlock - switch from closed-loop to open-loop mode
 * @td: DFLL instance
 *
 * Switch from CLOSED_LOOP state to OPEN_LOOP state. Returns 0 upon success,
 * or -EPERM if the DFLL is not currently in open-loop mode.
 */
static int dfll_unlock(struct tegra_dfll *td)
{
        switch (td->mode) {
        case DFLL_CLOSED_LOOP:
                dfll_set_open_loop_config(td);
                dfll_set_mode(td, DFLL_OPEN_LOOP);
                dfll_i2c_set_output_enabled(td, false);
                return 0;

        case DFLL_OPEN_LOOP:
                return 0;

        default:
                BUG_ON(td->mode > DFLL_CLOSED_LOOP);
                dev_err(td->dev, "%s: Cannot unlock DFLL in %s mode\n",
                        __func__, mode_name[td->mode]);
                return -EPERM;
        }
}

/*
 * Clock framework integration
 *
 * When the DFLL is being controlled by the CCF, always enter closed loop
 * mode when the clk is enabled. This requires that a DFLL rate request
 * has been set beforehand, which implies that a clk_set_rate() call is
 * always required before a clk_enable().
 */

static int dfll_clk_is_enabled(struct clk_hw *hw)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);

        return dfll_is_running(td);
}

static int dfll_clk_enable(struct clk_hw *hw)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);
        int ret;

        ret = dfll_enable(td);
        if (ret)
                return ret;

        ret = dfll_lock(td);
        if (ret)
                dfll_disable(td);

        return ret;
}

static void dfll_clk_disable(struct clk_hw *hw)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);
        int ret;

        ret = dfll_unlock(td);
        if (!ret)
                dfll_disable(td);
}

static unsigned long dfll_clk_recalc_rate(struct clk_hw *hw,
                                          unsigned long parent_rate)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);

        return td->last_unrounded_rate;
}

/* Must use determine_rate since it allows for rates exceeding 2^31-1 */
static int dfll_clk_determine_rate(struct clk_hw *hw,
                                   struct clk_rate_request *clk_req)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);
        struct dfll_rate_req req;
        int ret;

        ret = dfll_calculate_rate_request(td, &req, clk_req->rate);
        if (ret)
                return ret;

        /*
         * Don't set the rounded rate, since it doesn't really matter as
         * the output rate will be voltage controlled anyway, and cpufreq
         * freaks out if any rounding happens.
         */

        return 0;
}

static int dfll_clk_set_rate(struct clk_hw *hw, unsigned long rate,
                             unsigned long parent_rate)
{
        struct tegra_dfll *td = clk_hw_to_dfll(hw);

        return dfll_request_rate(td, rate);
}

static const struct clk_ops dfll_clk_ops = {
        .is_enabled     = dfll_clk_is_enabled,
        .enable         = dfll_clk_enable,
        .disable        = dfll_clk_disable,
        .recalc_rate    = dfll_clk_recalc_rate,
        .determine_rate = dfll_clk_determine_rate,
        .set_rate       = dfll_clk_set_rate,
};

static struct clk_init_data dfll_clk_init_data = {
        .flags          = CLK_IS_ROOT,
        .ops            = &dfll_clk_ops,
        .num_parents    = 0,
};

/**
 * dfll_register_clk - register the DFLL output clock with the clock framework
 * @td: DFLL instance
 *
 * Register the DFLL's output clock with the Linux clock framework and register
 * the DFLL driver as an OF clock provider. Returns 0 upon success or -EINVAL
 * or -ENOMEM upon failure.
 */
static int dfll_register_clk(struct tegra_dfll *td)
{
        int ret;

        dfll_clk_init_data.name = td->output_clock_name;
        td->dfll_clk_hw.init = &dfll_clk_init_data;

        td->dfll_clk = clk_register(td->dev, &td->dfll_clk_hw);
        if (IS_ERR(td->dfll_clk)) {
                dev_err(td->dev, "DFLL clock registration error\n");
                return -EINVAL;
        }

        ret = of_clk_add_provider(td->dev->of_node, of_clk_src_simple_get,
                                  td->dfll_clk);
        if (ret) {
                dev_err(td->dev, "of_clk_add_provider() failed\n");

                clk_unregister(td->dfll_clk);
                return ret;
        }

        return 0;
}

/**
 * dfll_unregister_clk - unregister the DFLL output clock
 * @td: DFLL instance
 *
 * Unregister the DFLL's output clock from the Linux clock framework
 * and from clkdev. No return value.
 */
static void dfll_unregister_clk(struct tegra_dfll *td)
{
        of_clk_del_provider(td->dev->of_node);
        clk_unregister(td->dfll_clk);
        td->dfll_clk = NULL;
}

/*
 * Debugfs interface
 */

#ifdef CONFIG_DEBUG_FS
/*
 * Monitor control
 */

/**
 * dfll_calc_monitored_rate - convert DFLL_MONITOR_DATA_VAL rate into real freq
 * @monitor_data: value read from the DFLL_MONITOR_DATA_VAL bitfield
 * @ref_rate: DFLL reference clock rate
 *
 * Convert @monitor_data from DFLL_MONITOR_DATA_VAL units into cycles
 * per second. Returns the converted value.
 */
static u64 dfll_calc_monitored_rate(u32 monitor_data,
                                    unsigned long ref_rate)
{
        return monitor_data * (ref_rate / REF_CLK_CYC_PER_DVCO_SAMPLE);
}

/**
 * dfll_read_monitor_rate - return the DFLL's output rate from internal monitor
 * @td: DFLL instance
 *
 * If the DFLL is enabled, return the last rate reported by the DFLL's
 * internal monitoring hardware. This works in both open-loop and
 * closed-loop mode, and takes the output scaler setting into account.
 * Assumes that the monitor was programmed to monitor frequency before
 * the sample period started. If the driver believes that the DFLL is
 * currently uninitialized or disabled, it will return 0, since
 * otherwise the DFLL monitor data register will return the last
 * measured rate from when the DFLL was active.
 */
static u64 dfll_read_monitor_rate(struct tegra_dfll *td)
{
        u32 v, s;
        u64 pre_scaler_rate, post_scaler_rate;

        if (!dfll_is_running(td))
                return 0;

        v = dfll_readl(td, DFLL_MONITOR_DATA);
        v = (v & DFLL_MONITOR_DATA_VAL_MASK) >> DFLL_MONITOR_DATA_VAL_SHIFT;
        pre_scaler_rate = dfll_calc_monitored_rate(v, td->ref_rate);

        s = dfll_readl(td, DFLL_FREQ_REQ);
        s = (s & DFLL_FREQ_REQ_SCALE_MASK) >> DFLL_FREQ_REQ_SCALE_SHIFT;
        post_scaler_rate = dfll_scale_dvco_rate(s, pre_scaler_rate);

        return post_scaler_rate;
}

static int attr_enable_get(void *data, u64 *val)
{
        struct tegra_dfll *td = data;

        *val = dfll_is_running(td);

        return 0;
}
static int attr_enable_set(void *data, u64 val)
{
        struct tegra_dfll *td = data;

        return val ? dfll_enable(td) : dfll_disable(td);
}
DEFINE_SIMPLE_ATTRIBUTE(enable_fops, attr_enable_get, attr_enable_set,
                        "%llu\n");

static int attr_lock_get(void *data, u64 *val)
{
        struct tegra_dfll *td = data;

        *val = (td->mode == DFLL_CLOSED_LOOP);

        return 0;
}
static int attr_lock_set(void *data, u64 val)
{
        struct tegra_dfll *td = data;

        return val ? dfll_lock(td) :  dfll_unlock(td);
}
DEFINE_SIMPLE_ATTRIBUTE(lock_fops, attr_lock_get, attr_lock_set,
                        "%llu\n");

static int attr_rate_get(void *data, u64 *val)
{
        struct tegra_dfll *td = data;

        *val = dfll_read_monitor_rate(td);

        return 0;
}

static int attr_rate_set(void *data, u64 val)
{
        struct tegra_dfll *td = data;

        return dfll_request_rate(td, val);
}
DEFINE_SIMPLE_ATTRIBUTE(rate_fops, attr_rate_get, attr_rate_set, "%llu\n");

static int attr_registers_show(struct seq_file *s, void *data)
{
        u32 val, offs;
        struct tegra_dfll *td = s->private;

        seq_puts(s, "CONTROL REGISTERS:\n");
        for (offs = 0; offs <= DFLL_MONITOR_DATA; offs += 4) {
                if (offs == DFLL_OUTPUT_CFG)
                        val = dfll_i2c_readl(td, offs);
                else
                        val = dfll_readl(td, offs);
                seq_printf(s, "[0x%02x] = 0x%08x\n", offs, val);
        }

        seq_puts(s, "\nI2C and INTR REGISTERS:\n");
        for (offs = DFLL_I2C_CFG; offs <= DFLL_I2C_STS; offs += 4)
                seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
                           dfll_i2c_readl(td, offs));
        for (offs = DFLL_INTR_STS; offs <= DFLL_INTR_EN; offs += 4)
                seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
                           dfll_i2c_readl(td, offs));

        seq_puts(s, "\nINTEGRATED I2C CONTROLLER REGISTERS:\n");
        offs = DFLL_I2C_CLK_DIVISOR;
        seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
                   __raw_readl(td->i2c_controller_base + offs));

        seq_puts(s, "\nLUT:\n");
        for (offs = 0; offs <  4 * MAX_DFLL_VOLTAGES; offs += 4)
                seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
                           __raw_readl(td->lut_base + offs));

        return 0;
}

static int attr_registers_open(struct inode *inode, struct file *file)
{
        return single_open(file, attr_registers_show, inode->i_private);
}

static const struct file_operations attr_registers_fops = {
        .open           = attr_registers_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int dfll_debug_init(struct tegra_dfll *td)
{
        int ret;

        if (!td || (td->mode == DFLL_UNINITIALIZED))
                return 0;

        td->debugfs_dir = debugfs_create_dir("tegra_dfll_fcpu", NULL);
        if (!td->debugfs_dir)
                return -ENOMEM;

        ret = -ENOMEM;

        if (!debugfs_create_file("enable", S_IRUGO | S_IWUSR,
                                 td->debugfs_dir, td, &enable_fops))
                goto err_out;

        if (!debugfs_create_file("lock", S_IRUGO,
                                 td->debugfs_dir, td, &lock_fops))
                goto err_out;

        if (!debugfs_create_file("rate", S_IRUGO,
                                 td->debugfs_dir, td, &rate_fops))
                goto err_out;

        if (!debugfs_create_file("registers", S_IRUGO,
                                 td->debugfs_dir, td, &attr_registers_fops))
                goto err_out;

        return 0;

err_out:
        debugfs_remove_recursive(td->debugfs_dir);
        return ret;
}

#endif /* CONFIG_DEBUG_FS */

/*
 * DFLL initialization
 */

/**
 * dfll_set_default_params - program non-output related DFLL parameters
 * @td: DFLL instance
 *
 * During DFLL driver initialization or resume from context loss,
 * program parameters for the closed loop integrator, DVCO tuning,
 * voltage droop control and monitor control.
 */
static void dfll_set_default_params(struct tegra_dfll *td)
{
        u32 val;

        val = DIV_ROUND_UP(td->ref_rate, td->sample_rate * 32);
        BUG_ON(val > DFLL_CONFIG_DIV_MASK);
        dfll_writel(td, val, DFLL_CONFIG);

        val = (td->force_mode << DFLL_PARAMS_FORCE_MODE_SHIFT) |
                (td->cf << DFLL_PARAMS_CF_PARAM_SHIFT) |
                (td->ci << DFLL_PARAMS_CI_PARAM_SHIFT) |
                (td->cg << DFLL_PARAMS_CG_PARAM_SHIFT) |
                (td->cg_scale ? DFLL_PARAMS_CG_SCALE : 0);
        dfll_writel(td, val, DFLL_PARAMS);

        dfll_tune_low(td);
        dfll_writel(td, td->droop_ctrl, DFLL_DROOP_CTRL);
        dfll_writel(td, DFLL_MONITOR_CTRL_FREQ, DFLL_MONITOR_CTRL);
}

/**
 * dfll_init_clks - clk_get() the DFLL source clocks
 * @td: DFLL instance
 *
 * Call clk_get() on the DFLL source clocks and save the pointers for later
 * use. Returns 0 upon success or error (see devm_clk_get) if one or more
 * of the clocks couldn't be looked up.
 */
static int dfll_init_clks(struct tegra_dfll *td)
{
        td->ref_clk = devm_clk_get(td->dev, "ref");
        if (IS_ERR(td->ref_clk)) {
                dev_err(td->dev, "missing ref clock\n");
                return PTR_ERR(td->ref_clk);
        }

        td->soc_clk = devm_clk_get(td->dev, "soc");
        if (IS_ERR(td->soc_clk)) {
                dev_err(td->dev, "missing soc clock\n");
                return PTR_ERR(td->soc_clk);
        }

        td->i2c_clk = devm_clk_get(td->dev, "i2c");
        if (IS_ERR(td->i2c_clk)) {
                dev_err(td->dev, "missing i2c clock\n");
                return PTR_ERR(td->i2c_clk);
        }
        td->i2c_clk_rate = clk_get_rate(td->i2c_clk);

        return 0;
}

/**
 * dfll_init - Prepare the DFLL IP block for use
 * @td: DFLL instance
 *
 * Do everything necessary to prepare the DFLL IP block for use. The
 * DFLL will be left in DISABLED state. Called by dfll_probe().
 * Returns 0 upon success, or passes along the error from whatever
 * function returned it.
 */
static int dfll_init(struct tegra_dfll *td)
{
        int ret;

        td->ref_rate = clk_get_rate(td->ref_clk);
        if (td->ref_rate != REF_CLOCK_RATE) {
                dev_err(td->dev, "unexpected ref clk rate %lu, expecting %lu",
                        td->ref_rate, REF_CLOCK_RATE);
                return -EINVAL;
        }

        reset_control_deassert(td->dvco_rst);

        ret = clk_prepare(td->ref_clk);
        if (ret) {
                dev_err(td->dev, "failed to prepare ref_clk\n");
                return ret;
        }

        ret = clk_prepare(td->soc_clk);
        if (ret) {
                dev_err(td->dev, "failed to prepare soc_clk\n");
                goto di_err1;
        }

        ret = clk_prepare(td->i2c_clk);
        if (ret) {
                dev_err(td->dev, "failed to prepare i2c_clk\n");
                goto di_err2;
        }

        td->last_unrounded_rate = 0;

        pm_runtime_enable(td->dev);
        pm_runtime_get_sync(td->dev);

        dfll_set_mode(td, DFLL_DISABLED);
        dfll_set_default_params(td);

        if (td->soc->init_clock_trimmers)
                td->soc->init_clock_trimmers();

        dfll_set_open_loop_config(td);

        dfll_init_out_if(td);

        pm_runtime_put_sync(td->dev);

        return 0;

di_err2:
        clk_unprepare(td->soc_clk);
di_err1:
        clk_unprepare(td->ref_clk);

        reset_control_assert(td->dvco_rst);

        return ret;
}

/*
 * DT data fetch
 */

/*
 * Find a PMIC voltage register-to-voltage mapping for the given voltage.
 * An exact voltage match is required.
 */
static int find_vdd_map_entry_exact(struct tegra_dfll *td, int uV)
{
        int i, n_voltages, reg_uV;

        n_voltages = regulator_count_voltages(td->vdd_reg);
        for (i = 0; i < n_voltages; i++) {
                reg_uV = regulator_list_voltage(td->vdd_reg, i);
                if (reg_uV < 0)
                        break;

                if (uV == reg_uV)
                        return i;
        }

        dev_err(td->dev, "no voltage map entry for %d uV\n", uV);
        return -EINVAL;
}

/*
 * Find a PMIC voltage register-to-voltage mapping for the given voltage,
 * rounding up to the closest supported voltage.
 * */
static int find_vdd_map_entry_min(struct tegra_dfll *td, int uV)
{
        int i, n_voltages, reg_uV;

        n_voltages = regulator_count_voltages(td->vdd_reg);
        for (i = 0; i < n_voltages; i++) {
                reg_uV = regulator_list_voltage(td->vdd_reg, i);
                if (reg_uV < 0)
                        break;

                if (uV <= reg_uV)
                        return i;
        }

        dev_err(td->dev, "no voltage map entry rounding to %d uV\n", uV);
        return -EINVAL;
}

/**
 * dfll_build_i2c_lut - build the I2C voltage register lookup table
 * @td: DFLL instance
 *
 * The DFLL hardware has 33 bytes of look-up table RAM that must be filled with
 * PMIC voltage register values that span the entire DFLL operating range.
 * This function builds the look-up table based on the OPP table provided by
 * the soc-specific platform driver (td->soc->opp_dev) and the PMIC
 * register-to-voltage mapping queried from the regulator framework.
 *
 * On success, fills in td->i2c_lut and returns 0, or -err on failure.
 */
static int dfll_build_i2c_lut(struct tegra_dfll *td)
{
        int ret = -EINVAL;
        int j, v, v_max, v_opp;
        int selector;
        unsigned long rate;
        struct dev_pm_opp *opp;
        int lut;

        rcu_read_lock();

        rate = ULONG_MAX;
        opp = dev_pm_opp_find_freq_floor(td->soc->dev, &rate);
        if (IS_ERR(opp)) {
                dev_err(td->dev, "couldn't get vmax opp, empty opp table?\n");
                goto out;
        }
        v_max = dev_pm_opp_get_voltage(opp);

        v = td->soc->min_millivolts * 1000;
        lut = find_vdd_map_entry_exact(td, v);
        if (lut < 0)
                goto out;
        td->i2c_lut[0] = lut;

        for (j = 1, rate = 0; ; rate++) {
                opp = dev_pm_opp_find_freq_ceil(td->soc->dev, &rate);
                if (IS_ERR(opp))
                        break;
                v_opp = dev_pm_opp_get_voltage(opp);

                if (v_opp <= td->soc->min_millivolts * 1000)
                        td->dvco_rate_min = dev_pm_opp_get_freq(opp);

                for (;;) {
                        v += max(1, (v_max - v) / (MAX_DFLL_VOLTAGES - j));
                        if (v >= v_opp)
                                break;

                        selector = find_vdd_map_entry_min(td, v);
                        if (selector < 0)
                                goto out;
                        if (selector != td->i2c_lut[j - 1])
                                td->i2c_lut[j++] = selector;
                }

                v = (j == MAX_DFLL_VOLTAGES - 1) ? v_max : v_opp;
                selector = find_vdd_map_entry_exact(td, v);
                if (selector < 0)
                        goto out;
                if (selector != td->i2c_lut[j - 1])
                        td->i2c_lut[j++] = selector;

                if (v >= v_max)
                        break;
        }
        td->i2c_lut_size = j;

        if (!td->dvco_rate_min)
                dev_err(td->dev, "no opp above DFLL minimum voltage %d mV\n",
                        td->soc->min_millivolts);
        else
                ret = 0;

out:
        rcu_read_unlock();

        return ret;
}

/**
 * read_dt_param - helper function for reading required parameters from the DT
 * @td: DFLL instance
 * @param: DT property name
 * @dest: output pointer for the value read
 *
 * Read a required numeric parameter from the DFLL device node, or complain
 * if the property doesn't exist. Returns a boolean indicating success for
 * easy chaining of multiple calls to this function.
 */
static bool read_dt_param(struct tegra_dfll *td, const char *param, u32 *dest)
{
        int err = of_property_read_u32(td->dev->of_node, param, dest);

        if (err < 0) {
                dev_err(td->dev, "failed to read DT parameter %s: %d\n",
                        param, err);
                return false;
        }

        return true;
}

/**
 * dfll_fetch_i2c_params - query PMIC I2C params from DT & regulator subsystem
 * @td: DFLL instance
 *
 * Read all the parameters required for operation in I2C mode. The parameters
 * can originate from the device tree or the regulator subsystem.
 * Returns 0 on success or -err on failure.
 */
static int dfll_fetch_i2c_params(struct tegra_dfll *td)
{
        struct regmap *regmap;
        struct device *i2c_dev;
        struct i2c_client *i2c_client;
        int vsel_reg, vsel_mask;
        int ret;

        if (!read_dt_param(td, "nvidia,i2c-fs-rate", &td->i2c_fs_rate))
                return -EINVAL;

        regmap = regulator_get_regmap(td->vdd_reg);
        i2c_dev = regmap_get_device(regmap);
        i2c_client = to_i2c_client(i2c_dev);

        td->i2c_slave_addr = i2c_client->addr;

        ret = regulator_get_hardware_vsel_register(td->vdd_reg,
                                                   &vsel_reg,
                                                   &vsel_mask);
        if (ret < 0) {
                dev_err(td->dev,
                        "regulator unsuitable for DFLL I2C operation\n");
                return -EINVAL;
        }
        td->i2c_reg = vsel_reg;

        ret = dfll_build_i2c_lut(td);
        if (ret) {
                dev_err(td->dev, "couldn't build I2C LUT\n");
                return ret;
        }

        return 0;
}

/**
 * dfll_fetch_common_params - read DFLL parameters from the device tree
 * @td: DFLL instance
 *
 * Read all the DT parameters that are common to both I2C and PWM operation.
 * Returns 0 on success or -EINVAL on any failure.
 */
static int dfll_fetch_common_params(struct tegra_dfll *td)
{
        bool ok = true;

        ok &= read_dt_param(td, "nvidia,droop-ctrl", &td->droop_ctrl);
        ok &= read_dt_param(td, "nvidia,sample-rate", &td->sample_rate);
        ok &= read_dt_param(td, "nvidia,force-mode", &td->force_mode);
        ok &= read_dt_param(td, "nvidia,cf", &td->cf);
        ok &= read_dt_param(td, "nvidia,ci", &td->ci);
        ok &= read_dt_param(td, "nvidia,cg", &td->cg);
        td->cg_scale = of_property_read_bool(td->dev->of_node,
                                             "nvidia,cg-scale");

        if (of_property_read_string(td->dev->of_node, "clock-output-names",
                                    &td->output_clock_name)) {
                dev_err(td->dev, "missing clock-output-names property\n");
                ok = false;
        }

        return ok ? 0 : -EINVAL;
}

/*
 * API exported to per-SoC platform drivers
 */

/**
 * tegra_dfll_register - probe a Tegra DFLL device
 * @pdev: DFLL platform_device *
 * @soc: Per-SoC integration and characterization data for this DFLL instance
 *
 * Probe and initialize a DFLL device instance. Intended to be called
 * by a SoC-specific shim driver that passes in per-SoC integration
 * and configuration data via @soc. Returns 0 on success or -err on failure.
 */
int tegra_dfll_register(struct platform_device *pdev,
                        struct tegra_dfll_soc_data *soc)
{
        struct resource *mem;
        struct tegra_dfll *td;
        int ret;

        if (!soc) {
                dev_err(&pdev->dev, "no tegra_dfll_soc_data provided\n");
                return -EINVAL;
        }

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

        td->soc = soc;

        td->vdd_reg = devm_regulator_get(td->dev, "vdd-cpu");
        if (IS_ERR(td->vdd_reg)) {
                dev_err(td->dev, "couldn't get vdd_cpu regulator\n");
                return PTR_ERR(td->vdd_reg);
        }

        td->dvco_rst = devm_reset_control_get(td->dev, "dvco");
        if (IS_ERR(td->dvco_rst)) {
                dev_err(td->dev, "couldn't get dvco reset\n");
                return PTR_ERR(td->dvco_rst);
        }

        ret = dfll_fetch_common_params(td);
        if (ret) {
                dev_err(td->dev, "couldn't parse device tree parameters\n");
                return ret;
        }

        ret = dfll_fetch_i2c_params(td);
        if (ret)
                return ret;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!mem) {
                dev_err(td->dev, "no control register resource\n");
                return -ENODEV;
        }

        td->base = devm_ioremap(td->dev, mem->start, resource_size(mem));
        if (!td->base) {
                dev_err(td->dev, "couldn't ioremap DFLL control registers\n");
                return -ENODEV;
        }

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!mem) {
                dev_err(td->dev, "no i2c_base resource\n");
                return -ENODEV;
        }

        td->i2c_base = devm_ioremap(td->dev, mem->start, resource_size(mem));
        if (!td->i2c_base) {
                dev_err(td->dev, "couldn't ioremap i2c_base resource\n");
                return -ENODEV;
        }

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 2);
        if (!mem) {
                dev_err(td->dev, "no i2c_controller_base resource\n");
                return -ENODEV;
        }

        td->i2c_controller_base = devm_ioremap(td->dev, mem->start,
                                               resource_size(mem));
        if (!td->i2c_controller_base) {
                dev_err(td->dev,
                        "couldn't ioremap i2c_controller_base resource\n");
                return -ENODEV;
        }

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 3);
        if (!mem) {
                dev_err(td->dev, "no lut_base resource\n");
                return -ENODEV;
        }

        td->lut_base = devm_ioremap(td->dev, mem->start, resource_size(mem));
        if (!td->lut_base) {
                dev_err(td->dev,
                        "couldn't ioremap lut_base resource\n");
                return -ENODEV;
        }

        ret = dfll_init_clks(td);
        if (ret) {
                dev_err(&pdev->dev, "DFLL clock init error\n");
                return ret;
        }

        /* Enable the clocks and set the device up */
        ret = dfll_init(td);
        if (ret)
                return ret;

        ret = dfll_register_clk(td);
        if (ret) {
                dev_err(&pdev->dev, "DFLL clk registration failed\n");
                return ret;
        }

#ifdef CONFIG_DEBUG_FS
        dfll_debug_init(td);
#endif

        return 0;
}
EXPORT_SYMBOL(tegra_dfll_register);

/**
 * tegra_dfll_unregister - release all of the DFLL driver resources for a device
 * @pdev: DFLL platform_device *
 *
 * Unbind this driver from the DFLL hardware device represented by
 * @pdev. The DFLL must be disabled for this to succeed. Returns 0
 * upon success or -EBUSY if the DFLL is still active.
 */
int tegra_dfll_unregister(struct platform_device *pdev)
{
        struct tegra_dfll *td = platform_get_drvdata(pdev);

        /* Try to prevent removal while the DFLL is active */
        if (td->mode != DFLL_DISABLED) {
                dev_err(&pdev->dev,
                        "must disable DFLL before removing driver\n");
                return -EBUSY;
        }

        debugfs_remove_recursive(td->debugfs_dir);

        dfll_unregister_clk(td);
        pm_runtime_disable(&pdev->dev);

        clk_unprepare(td->ref_clk);
        clk_unprepare(td->soc_clk);
        clk_unprepare(td->i2c_clk);

        reset_control_assert(td->dvco_rst);

        return 0;
}
EXPORT_SYMBOL(tegra_dfll_unregister);