/*
 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <subdev/clk.h>
#include <subdev/volt.h>
#include <subdev/timer.h>
#include <core/device.h>
#include <core/tegra.h>

#include "priv.h"
#include "gk20a.h"

#define GPCPLL_CFG_SYNC_MODE    BIT(2)

#define BYPASSCTRL_SYS  (SYS_GPCPLL_CFG_BASE + 0x340)
#define BYPASSCTRL_SYS_GPCPLL_SHIFT     0
#define BYPASSCTRL_SYS_GPCPLL_WIDTH     1

#define GPCPLL_CFG2_SDM_DIN_SHIFT       0
#define GPCPLL_CFG2_SDM_DIN_WIDTH       8
#define GPCPLL_CFG2_SDM_DIN_MASK        \
        (MASK(GPCPLL_CFG2_SDM_DIN_WIDTH) << GPCPLL_CFG2_SDM_DIN_SHIFT)
#define GPCPLL_CFG2_SDM_DIN_NEW_SHIFT   8
#define GPCPLL_CFG2_SDM_DIN_NEW_WIDTH   15
#define GPCPLL_CFG2_SDM_DIN_NEW_MASK    \
        (MASK(GPCPLL_CFG2_SDM_DIN_NEW_WIDTH) << GPCPLL_CFG2_SDM_DIN_NEW_SHIFT)
#define GPCPLL_CFG2_SETUP2_SHIFT        16
#define GPCPLL_CFG2_PLL_STEPA_SHIFT     24

#define GPCPLL_DVFS0    (SYS_GPCPLL_CFG_BASE + 0x10)
#define GPCPLL_DVFS0_DFS_COEFF_SHIFT    0
#define GPCPLL_DVFS0_DFS_COEFF_WIDTH    7
#define GPCPLL_DVFS0_DFS_COEFF_MASK     \
        (MASK(GPCPLL_DVFS0_DFS_COEFF_WIDTH) << GPCPLL_DVFS0_DFS_COEFF_SHIFT)
#define GPCPLL_DVFS0_DFS_DET_MAX_SHIFT  8
#define GPCPLL_DVFS0_DFS_DET_MAX_WIDTH  7
#define GPCPLL_DVFS0_DFS_DET_MAX_MASK   \
        (MASK(GPCPLL_DVFS0_DFS_DET_MAX_WIDTH) << GPCPLL_DVFS0_DFS_DET_MAX_SHIFT)

#define GPCPLL_DVFS1            (SYS_GPCPLL_CFG_BASE + 0x14)
#define GPCPLL_DVFS1_DFS_EXT_DET_SHIFT          0
#define GPCPLL_DVFS1_DFS_EXT_DET_WIDTH          7
#define GPCPLL_DVFS1_DFS_EXT_STRB_SHIFT         7
#define GPCPLL_DVFS1_DFS_EXT_STRB_WIDTH         1
#define GPCPLL_DVFS1_DFS_EXT_CAL_SHIFT          8
#define GPCPLL_DVFS1_DFS_EXT_CAL_WIDTH          7
#define GPCPLL_DVFS1_DFS_EXT_SEL_SHIFT          15
#define GPCPLL_DVFS1_DFS_EXT_SEL_WIDTH          1
#define GPCPLL_DVFS1_DFS_CTRL_SHIFT             16
#define GPCPLL_DVFS1_DFS_CTRL_WIDTH             12
#define GPCPLL_DVFS1_EN_SDM_SHIFT               28
#define GPCPLL_DVFS1_EN_SDM_WIDTH               1
#define GPCPLL_DVFS1_EN_SDM_BIT                 BIT(28)
#define GPCPLL_DVFS1_EN_DFS_SHIFT               29
#define GPCPLL_DVFS1_EN_DFS_WIDTH               1
#define GPCPLL_DVFS1_EN_DFS_BIT                 BIT(29)
#define GPCPLL_DVFS1_EN_DFS_CAL_SHIFT           30
#define GPCPLL_DVFS1_EN_DFS_CAL_WIDTH           1
#define GPCPLL_DVFS1_EN_DFS_CAL_BIT             BIT(30)
#define GPCPLL_DVFS1_DFS_CAL_DONE_SHIFT         31
#define GPCPLL_DVFS1_DFS_CAL_DONE_WIDTH         1
#define GPCPLL_DVFS1_DFS_CAL_DONE_BIT           BIT(31)

#define GPC_BCAST_GPCPLL_DVFS2  (GPC_BCAST_GPCPLL_CFG_BASE + 0x20)
#define GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT       BIT(16)

#define GPCPLL_CFG3_PLL_DFS_TESTOUT_SHIFT       24
#define GPCPLL_CFG3_PLL_DFS_TESTOUT_WIDTH       7

#define DFS_DET_RANGE   6       /* -2^6 ... 2^6-1 */
#define SDM_DIN_RANGE   12      /* -2^12 ... 2^12-1 */

struct gm20b_clk_dvfs_params {
        s32 coeff_slope;
        s32 coeff_offs;
        u32 vco_ctrl;
};

static const struct gm20b_clk_dvfs_params gm20b_dvfs_params = {
        .coeff_slope = -165230,
        .coeff_offs = 214007,
        .vco_ctrl = 0x7 << 3,
};

/*
 * base.n is now the *integer* part of the N factor.
 * sdm_din contains n's decimal part.
 */
struct gm20b_pll {
        struct gk20a_pll base;
        u32 sdm_din;
};

struct gm20b_clk_dvfs {
        u32 dfs_coeff;
        s32 dfs_det_max;
        s32 dfs_ext_cal;
};

struct gm20b_clk {
        /* currently applied parameters */
        struct gk20a_clk base;
        struct gm20b_clk_dvfs dvfs;
        u32 uv;

        /* new parameters to apply */
        struct gk20a_pll new_pll;
        struct gm20b_clk_dvfs new_dvfs;
        u32 new_uv;

        const struct gm20b_clk_dvfs_params *dvfs_params;

        /* fused parameters */
        s32 uvdet_slope;
        s32 uvdet_offs;

        /* safe frequency we can use at minimum voltage */
        u32 safe_fmax_vmin;
};
#define gm20b_clk(p) container_of((gk20a_clk(p)), struct gm20b_clk, base)

static u32 pl_to_div(u32 pl)
{
        return pl;
}

static u32 div_to_pl(u32 div)
{
        return div;
}

static const struct gk20a_clk_pllg_params gm20b_pllg_params = {
        .min_vco = 1300000, .max_vco = 2600000,
        .min_u = 12000, .max_u = 38400,
        .min_m = 1, .max_m = 255,
        .min_n = 8, .max_n = 255,
        .min_pl = 1, .max_pl = 31,
};

static void
gm20b_pllg_read_mnp(struct gm20b_clk *clk, struct gm20b_pll *pll)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        struct nvkm_device *device = subdev->device;
        u32 val;

        gk20a_pllg_read_mnp(&clk->base, &pll->base);
        val = nvkm_rd32(device, GPCPLL_CFG2);
        pll->sdm_din = (val >> GPCPLL_CFG2_SDM_DIN_SHIFT) &
                       MASK(GPCPLL_CFG2_SDM_DIN_WIDTH);
}

static void
gm20b_pllg_write_mnp(struct gm20b_clk *clk, const struct gm20b_pll *pll)
{
        struct nvkm_device *device = clk->base.base.subdev.device;

        nvkm_mask(device, GPCPLL_CFG2, GPCPLL_CFG2_SDM_DIN_MASK,
                  pll->sdm_din << GPCPLL_CFG2_SDM_DIN_SHIFT);
        gk20a_pllg_write_mnp(&clk->base, &pll->base);
}

/*
 * Determine DFS_COEFF for the requested voltage. Always select external
 * calibration override equal to the voltage, and set maximum detection
 * limit "0" (to make sure that PLL output remains under F/V curve when
 * voltage increases).
 */
static void
gm20b_dvfs_calc_det_coeff(struct gm20b_clk *clk, s32 uv,
                          struct gm20b_clk_dvfs *dvfs)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        const struct gm20b_clk_dvfs_params *p = clk->dvfs_params;
        u32 coeff;
        /* Work with mv as uv would likely trigger an overflow */
        s32 mv = DIV_ROUND_CLOSEST(uv, 1000);

        /* coeff = slope * voltage + offset */
        coeff = DIV_ROUND_CLOSEST(mv * p->coeff_slope, 1000) + p->coeff_offs;
        coeff = DIV_ROUND_CLOSEST(coeff, 1000);
        dvfs->dfs_coeff = min_t(u32, coeff, MASK(GPCPLL_DVFS0_DFS_COEFF_WIDTH));

        dvfs->dfs_ext_cal = DIV_ROUND_CLOSEST(uv - clk->uvdet_offs,
                                             clk->uvdet_slope);
        /* should never happen */
        if (abs(dvfs->dfs_ext_cal) >= BIT(DFS_DET_RANGE))
                nvkm_error(subdev, "dfs_ext_cal overflow!\n");

        dvfs->dfs_det_max = 0;

        nvkm_debug(subdev, "%s uv: %d coeff: %x, ext_cal: %d, det_max: %d\n",
                   __func__, uv, dvfs->dfs_coeff, dvfs->dfs_ext_cal,
                   dvfs->dfs_det_max);
}

/*
 * Solve equation for integer and fractional part of the effective NDIV:
 *
 * n_eff = n_int + 1/2 + (SDM_DIN / 2^(SDM_DIN_RANGE + 1)) +
 *         (DVFS_COEFF * DVFS_DET_DELTA) / 2^DFS_DET_RANGE
 *
 * The SDM_DIN LSB is finally shifted out, since it is not accessible by sw.
 */
static void
gm20b_dvfs_calc_ndiv(struct gm20b_clk *clk, u32 n_eff, u32 *n_int, u32 *sdm_din)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        const struct gk20a_clk_pllg_params *p = clk->base.params;
        u32 n;
        s32 det_delta;
        u32 rem, rem_range;

        /* calculate current ext_cal and subtract previous one */
        det_delta = DIV_ROUND_CLOSEST(((s32)clk->uv) - clk->uvdet_offs,
                                      clk->uvdet_slope);
        det_delta -= clk->dvfs.dfs_ext_cal;
        det_delta = min(det_delta, clk->dvfs.dfs_det_max);
        det_delta *= clk->dvfs.dfs_coeff;

        /* integer part of n */
        n = (n_eff << DFS_DET_RANGE) - det_delta;
        /* should never happen! */
        if (n <= 0) {
                nvkm_error(subdev, "ndiv <= 0 - setting to 1...\n");
                n = 1 << DFS_DET_RANGE;
        }
        if (n >> DFS_DET_RANGE > p->max_n) {
                nvkm_error(subdev, "ndiv > max_n - setting to max_n...\n");
                n = p->max_n << DFS_DET_RANGE;
        }
        *n_int = n >> DFS_DET_RANGE;

        /* fractional part of n */
        rem = ((u32)n) & MASK(DFS_DET_RANGE);
        rem_range = SDM_DIN_RANGE + 1 - DFS_DET_RANGE;
        /* subtract 2^SDM_DIN_RANGE to account for the 1/2 of the equation */
        rem = (rem << rem_range) - BIT(SDM_DIN_RANGE);
        /* lose 8 LSB and clip - sdm_din only keeps the most significant byte */
        *sdm_din = (rem >> BITS_PER_BYTE) & MASK(GPCPLL_CFG2_SDM_DIN_WIDTH);

        nvkm_debug(subdev, "%s n_eff: %d, n_int: %d, sdm_din: %d\n", __func__,
                   n_eff, *n_int, *sdm_din);
}

static int
gm20b_pllg_slide(struct gm20b_clk *clk, u32 n)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        struct nvkm_device *device = subdev->device;
        struct gm20b_pll pll;
        u32 n_int, sdm_din;
        int ret = 0;

        /* calculate the new n_int/sdm_din for this n/uv */
        gm20b_dvfs_calc_ndiv(clk, n, &n_int, &sdm_din);

        /* get old coefficients */
        gm20b_pllg_read_mnp(clk, &pll);
        /* do nothing if NDIV is the same */
        if (n_int == pll.base.n && sdm_din == pll.sdm_din)
                return 0;

        /* pll slowdown mode */
        nvkm_mask(device, GPCPLL_NDIV_SLOWDOWN,
                BIT(GPCPLL_NDIV_SLOWDOWN_SLOWDOWN_USING_PLL_SHIFT),
                BIT(GPCPLL_NDIV_SLOWDOWN_SLOWDOWN_USING_PLL_SHIFT));

        /* new ndiv ready for ramp */
        /* in DVFS mode SDM is updated via "new" field */
        nvkm_mask(device, GPCPLL_CFG2, GPCPLL_CFG2_SDM_DIN_NEW_MASK,
                  sdm_din << GPCPLL_CFG2_SDM_DIN_NEW_SHIFT);
        pll.base.n = n_int;
        udelay(1);
        gk20a_pllg_write_mnp(&clk->base, &pll.base);

        /* dynamic ramp to new ndiv */
        udelay(1);
        nvkm_mask(device, GPCPLL_NDIV_SLOWDOWN,
                  BIT(GPCPLL_NDIV_SLOWDOWN_EN_DYNRAMP_SHIFT),
                  BIT(GPCPLL_NDIV_SLOWDOWN_EN_DYNRAMP_SHIFT));

        /* wait for ramping to complete */
        if (nvkm_wait_usec(device, 500, GPC_BCAST_NDIV_SLOWDOWN_DEBUG,
                GPC_BCAST_NDIV_SLOWDOWN_DEBUG_PLL_DYNRAMP_DONE_SYNCED_MASK,
                GPC_BCAST_NDIV_SLOWDOWN_DEBUG_PLL_DYNRAMP_DONE_SYNCED_MASK) < 0)
                ret = -ETIMEDOUT;

        /* in DVFS mode complete SDM update */
        nvkm_mask(device, GPCPLL_CFG2, GPCPLL_CFG2_SDM_DIN_MASK,
                  sdm_din << GPCPLL_CFG2_SDM_DIN_SHIFT);

        /* exit slowdown mode */
        nvkm_mask(device, GPCPLL_NDIV_SLOWDOWN,
                BIT(GPCPLL_NDIV_SLOWDOWN_SLOWDOWN_USING_PLL_SHIFT) |
                BIT(GPCPLL_NDIV_SLOWDOWN_EN_DYNRAMP_SHIFT), 0);
        nvkm_rd32(device, GPCPLL_NDIV_SLOWDOWN);

        return ret;
}

static int
gm20b_pllg_enable(struct gm20b_clk *clk)
{
        struct nvkm_device *device = clk->base.base.subdev.device;

        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_ENABLE, GPCPLL_CFG_ENABLE);
        nvkm_rd32(device, GPCPLL_CFG);

        /* In DVFS mode lock cannot be used - so just delay */
        udelay(40);

        /* set SYNC_MODE for glitchless switch out of bypass */
        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_SYNC_MODE,
                       GPCPLL_CFG_SYNC_MODE);
        nvkm_rd32(device, GPCPLL_CFG);

        /* switch to VCO mode */
        nvkm_mask(device, SEL_VCO, BIT(SEL_VCO_GPC2CLK_OUT_SHIFT),
                  BIT(SEL_VCO_GPC2CLK_OUT_SHIFT));

        return 0;
}

static void
gm20b_pllg_disable(struct gm20b_clk *clk)
{
        struct nvkm_device *device = clk->base.base.subdev.device;

        /* put PLL in bypass before disabling it */
        nvkm_mask(device, SEL_VCO, BIT(SEL_VCO_GPC2CLK_OUT_SHIFT), 0);

        /* clear SYNC_MODE before disabling PLL */
        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_SYNC_MODE, 0);

        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_ENABLE, 0);
        nvkm_rd32(device, GPCPLL_CFG);
}

static int
gm20b_pllg_program_mnp(struct gm20b_clk *clk, const struct gk20a_pll *pll)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        struct nvkm_device *device = subdev->device;
        struct gm20b_pll cur_pll;
        u32 n_int, sdm_din;
        /* if we only change pdiv, we can do a glitchless transition */
        bool pdiv_only;
        int ret;

        gm20b_dvfs_calc_ndiv(clk, pll->n, &n_int, &sdm_din);
        gm20b_pllg_read_mnp(clk, &cur_pll);
        pdiv_only = cur_pll.base.n == n_int && cur_pll.sdm_din == sdm_din &&
                    cur_pll.base.m == pll->m;

        /* need full sequence if clock not enabled yet */
        if (!gk20a_pllg_is_enabled(&clk->base))
                pdiv_only = false;

        /* split VCO-to-bypass jump in half by setting out divider 1:2 */
        nvkm_mask(device, GPC2CLK_OUT, GPC2CLK_OUT_VCODIV_MASK,
                  GPC2CLK_OUT_VCODIV2 << GPC2CLK_OUT_VCODIV_SHIFT);
        /* Intentional 2nd write to assure linear divider operation */
        nvkm_mask(device, GPC2CLK_OUT, GPC2CLK_OUT_VCODIV_MASK,
                  GPC2CLK_OUT_VCODIV2 << GPC2CLK_OUT_VCODIV_SHIFT);
        nvkm_rd32(device, GPC2CLK_OUT);
        udelay(2);

        if (pdiv_only) {
                u32 old = cur_pll.base.pl;
                u32 new = pll->pl;

                /*
                 * we can do a glitchless transition only if the old and new PL
                 * parameters share at least one bit set to 1. If this is not
                 * the case, calculate and program an interim PL that will allow
                 * us to respect that rule.
                 */
                if ((old & new) == 0) {
                        cur_pll.base.pl = min(old | BIT(ffs(new) - 1),
                                              new | BIT(ffs(old) - 1));
                        gk20a_pllg_write_mnp(&clk->base, &cur_pll.base);
                }

                cur_pll.base.pl = new;
                gk20a_pllg_write_mnp(&clk->base, &cur_pll.base);
        } else {
                /* disable before programming if more than pdiv changes */
                gm20b_pllg_disable(clk);

                cur_pll.base = *pll;
                cur_pll.base.n = n_int;
                cur_pll.sdm_din = sdm_din;
                gm20b_pllg_write_mnp(clk, &cur_pll);

                ret = gm20b_pllg_enable(clk);
                if (ret)
                        return ret;
        }

        /* restore out divider 1:1 */
        udelay(2);
        nvkm_mask(device, GPC2CLK_OUT, GPC2CLK_OUT_VCODIV_MASK,
                  GPC2CLK_OUT_VCODIV1 << GPC2CLK_OUT_VCODIV_SHIFT);
        /* Intentional 2nd write to assure linear divider operation */
        nvkm_mask(device, GPC2CLK_OUT, GPC2CLK_OUT_VCODIV_MASK,
                  GPC2CLK_OUT_VCODIV1 << GPC2CLK_OUT_VCODIV_SHIFT);
        nvkm_rd32(device, GPC2CLK_OUT);

        return 0;
}

static int
gm20b_pllg_program_mnp_slide(struct gm20b_clk *clk, const struct gk20a_pll *pll)
{
        struct gk20a_pll cur_pll;
        int ret;

        if (gk20a_pllg_is_enabled(&clk->base)) {
                gk20a_pllg_read_mnp(&clk->base, &cur_pll);

                /* just do NDIV slide if there is no change to M and PL */
                if (pll->m == cur_pll.m && pll->pl == cur_pll.pl)
                        return gm20b_pllg_slide(clk, pll->n);

                /* slide down to current NDIV_LO */
                cur_pll.n = gk20a_pllg_n_lo(&clk->base, &cur_pll);
                ret = gm20b_pllg_slide(clk, cur_pll.n);
                if (ret)
                        return ret;
        }

        /* program MNP with the new clock parameters and new NDIV_LO */
        cur_pll = *pll;
        cur_pll.n = gk20a_pllg_n_lo(&clk->base, &cur_pll);
        ret = gm20b_pllg_program_mnp(clk, &cur_pll);
        if (ret)
                return ret;

        /* slide up to new NDIV */
        return gm20b_pllg_slide(clk, pll->n);
}

static int
gm20b_clk_calc(struct nvkm_clk *base, struct nvkm_cstate *cstate)
{
        struct gm20b_clk *clk = gm20b_clk(base);
        struct nvkm_subdev *subdev = &base->subdev;
        struct nvkm_volt *volt = base->subdev.device->volt;
        int ret;

        ret = gk20a_pllg_calc_mnp(&clk->base, cstate->domain[nv_clk_src_gpc] *
                                             GK20A_CLK_GPC_MDIV, &clk->new_pll);
        if (ret)
                return ret;

        clk->new_uv = volt->vid[cstate->voltage].uv;
        gm20b_dvfs_calc_det_coeff(clk, clk->new_uv, &clk->new_dvfs);

        nvkm_debug(subdev, "%s uv: %d uv\n", __func__, clk->new_uv);

        return 0;
}

/*
 * Compute PLL parameters that are always safe for the current voltage
 */
static void
gm20b_dvfs_calc_safe_pll(struct gm20b_clk *clk, struct gk20a_pll *pll)
{
        u32 rate = gk20a_pllg_calc_rate(&clk->base, pll) / KHZ;
        u32 parent_rate = clk->base.parent_rate / KHZ;
        u32 nmin, nsafe;

        /* remove a safe margin of 10% */
        if (rate > clk->safe_fmax_vmin)
                rate = rate * (100 - 10) / 100;

        /* gpc2clk */
        rate *= 2;

        nmin = DIV_ROUND_UP(pll->m * clk->base.params->min_vco, parent_rate);
        nsafe = pll->m * rate / (clk->base.parent_rate);

        if (nsafe < nmin) {
                pll->pl = DIV_ROUND_UP(nmin * parent_rate, pll->m * rate);
                nsafe = nmin;
        }

        pll->n = nsafe;
}

static void
gm20b_dvfs_program_coeff(struct gm20b_clk *clk, u32 coeff)
{
        struct nvkm_device *device = clk->base.base.subdev.device;

        /* strobe to read external DFS coefficient */
        nvkm_mask(device, GPC_BCAST_GPCPLL_DVFS2,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT);

        nvkm_mask(device, GPCPLL_DVFS0, GPCPLL_DVFS0_DFS_COEFF_MASK,
                  coeff << GPCPLL_DVFS0_DFS_COEFF_SHIFT);

        udelay(1);
        nvkm_mask(device, GPC_BCAST_GPCPLL_DVFS2,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT, 0);
}

static void
gm20b_dvfs_program_ext_cal(struct gm20b_clk *clk, u32 dfs_det_cal)
{
        struct nvkm_device *device = clk->base.base.subdev.device;
        u32 val;

        nvkm_mask(device, GPC_BCAST_GPCPLL_DVFS2, MASK(DFS_DET_RANGE + 1),
                  dfs_det_cal);
        udelay(1);

        val = nvkm_rd32(device, GPCPLL_DVFS1);
        if (!(val & BIT(25))) {
                /* Use external value to overwrite calibration value */
                val |= BIT(25) | BIT(16);
                nvkm_wr32(device, GPCPLL_DVFS1, val);
        }
}

static void
gm20b_dvfs_program_dfs_detection(struct gm20b_clk *clk,
                                 struct gm20b_clk_dvfs *dvfs)
{
        struct nvkm_device *device = clk->base.base.subdev.device;

        /* strobe to read external DFS coefficient */
        nvkm_mask(device, GPC_BCAST_GPCPLL_DVFS2,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT);

        nvkm_mask(device, GPCPLL_DVFS0,
                  GPCPLL_DVFS0_DFS_COEFF_MASK | GPCPLL_DVFS0_DFS_DET_MAX_MASK,
                  dvfs->dfs_coeff << GPCPLL_DVFS0_DFS_COEFF_SHIFT |
                  dvfs->dfs_det_max << GPCPLL_DVFS0_DFS_DET_MAX_SHIFT);

        udelay(1);
        nvkm_mask(device, GPC_BCAST_GPCPLL_DVFS2,
                  GPC_BCAST_GPCPLL_DVFS2_DFS_EXT_STROBE_BIT, 0);

        gm20b_dvfs_program_ext_cal(clk, dvfs->dfs_ext_cal);
}

static int
gm20b_clk_prog(struct nvkm_clk *base)
{
        struct gm20b_clk *clk = gm20b_clk(base);
        u32 cur_freq;
        int ret;

        /* No change in DVFS settings? */
        if (clk->uv == clk->new_uv)
                goto prog;

        /*
         * Interim step for changing DVFS detection settings: low enough
         * frequency to be safe at at DVFS coeff = 0.
         *
         * 1. If voltage is increasing:
         * - safe frequency target matches the lowest - old - frequency
         * - DVFS settings are still old
         * - Voltage already increased to new level by volt, but maximum
         *   detection limit assures PLL output remains under F/V curve
         *
         * 2. If voltage is decreasing:
         * - safe frequency target matches the lowest - new - frequency
         * - DVFS settings are still old
         * - Voltage is also old, it will be lowered by volt afterwards
         *
         * Interim step can be skipped if old frequency is below safe minimum,
         * i.e., it is low enough to be safe at any voltage in operating range
         * with zero DVFS coefficient.
         */
        cur_freq = nvkm_clk_read(&clk->base.base, nv_clk_src_gpc);
        if (cur_freq > clk->safe_fmax_vmin) {
                struct gk20a_pll pll_safe;

                if (clk->uv < clk->new_uv)
                        /* voltage will raise: safe frequency is current one */
                        pll_safe = clk->base.pll;
                else
                        /* voltage will drop: safe frequency is new one */
                        pll_safe = clk->new_pll;

                gm20b_dvfs_calc_safe_pll(clk, &pll_safe);
                ret = gm20b_pllg_program_mnp_slide(clk, &pll_safe);
                if (ret)
                        return ret;
        }

        /*
         * DVFS detection settings transition:
         * - Set DVFS coefficient zero
         * - Set calibration level to new voltage
         * - Set DVFS coefficient to match new voltage
         */
        gm20b_dvfs_program_coeff(clk, 0);
        gm20b_dvfs_program_ext_cal(clk, clk->new_dvfs.dfs_ext_cal);
        gm20b_dvfs_program_coeff(clk, clk->new_dvfs.dfs_coeff);
        gm20b_dvfs_program_dfs_detection(clk, &clk->new_dvfs);

prog:
        clk->uv = clk->new_uv;
        clk->dvfs = clk->new_dvfs;
        clk->base.pll = clk->new_pll;

        return gm20b_pllg_program_mnp_slide(clk, &clk->base.pll);
}

static struct nvkm_pstate
gm20b_pstates[] = {
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 76800,
                        .voltage = 0,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 153600,
                        .voltage = 1,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 230400,
                        .voltage = 2,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 307200,
                        .voltage = 3,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 384000,
                        .voltage = 4,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 460800,
                        .voltage = 5,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 537600,
                        .voltage = 6,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 614400,
                        .voltage = 7,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 691200,
                        .voltage = 8,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 768000,
                        .voltage = 9,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 844800,
                        .voltage = 10,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 921600,
                        .voltage = 11,
                },
        },
        {
                .base = {
                        .domain[nv_clk_src_gpc] = 998400,
                        .voltage = 12,
                },
        },
};

static void
gm20b_clk_fini(struct nvkm_clk *base)
{
        struct nvkm_device *device = base->subdev.device;
        struct gm20b_clk *clk = gm20b_clk(base);

        /* slide to VCO min */
        if (gk20a_pllg_is_enabled(&clk->base)) {
                struct gk20a_pll pll;
                u32 n_lo;

                gk20a_pllg_read_mnp(&clk->base, &pll);
                n_lo = gk20a_pllg_n_lo(&clk->base, &pll);
                gm20b_pllg_slide(clk, n_lo);
        }

        gm20b_pllg_disable(clk);

        /* set IDDQ */
        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_IDDQ, 1);
}

static int
gm20b_clk_init_dvfs(struct gm20b_clk *clk)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        struct nvkm_device *device = subdev->device;
        bool fused = clk->uvdet_offs && clk->uvdet_slope;
        static const s32 ADC_SLOPE_UV = 10000; /* default ADC detection slope */
        u32 data;
        int ret;

        /* Enable NA DVFS */
        nvkm_mask(device, GPCPLL_DVFS1, GPCPLL_DVFS1_EN_DFS_BIT,
                  GPCPLL_DVFS1_EN_DFS_BIT);

        /* Set VCO_CTRL */
        if (clk->dvfs_params->vco_ctrl)
                nvkm_mask(device, GPCPLL_CFG3, GPCPLL_CFG3_VCO_CTRL_MASK,
                      clk->dvfs_params->vco_ctrl << GPCPLL_CFG3_VCO_CTRL_SHIFT);

        if (fused) {
                /* Start internal calibration, but ignore results */
                nvkm_mask(device, GPCPLL_DVFS1, GPCPLL_DVFS1_EN_DFS_CAL_BIT,
                          GPCPLL_DVFS1_EN_DFS_CAL_BIT);

                /* got uvdev parameters from fuse, skip calibration */
                goto calibrated;
        }

        /*
         * If calibration parameters are not fused, start internal calibration,
         * wait for completion, and use results along with default slope to
         * calculate ADC offset during boot.
         */
        nvkm_mask(device, GPCPLL_DVFS1, GPCPLL_DVFS1_EN_DFS_CAL_BIT,
                          GPCPLL_DVFS1_EN_DFS_CAL_BIT);

        /* Wait for internal calibration done (spec < 2us). */
        ret = nvkm_wait_usec(device, 10, GPCPLL_DVFS1,
                             GPCPLL_DVFS1_DFS_CAL_DONE_BIT,
                             GPCPLL_DVFS1_DFS_CAL_DONE_BIT);
        if (ret < 0) {
                nvkm_error(subdev, "GPCPLL calibration timeout\n");
                return -ETIMEDOUT;
        }

        data = nvkm_rd32(device, GPCPLL_CFG3) >>
                         GPCPLL_CFG3_PLL_DFS_TESTOUT_SHIFT;
        data &= MASK(GPCPLL_CFG3_PLL_DFS_TESTOUT_WIDTH);

        clk->uvdet_slope = ADC_SLOPE_UV;
        clk->uvdet_offs = ((s32)clk->uv) - data * ADC_SLOPE_UV;

        nvkm_debug(subdev, "calibrated DVFS parameters: offs %d, slope %d\n",
                   clk->uvdet_offs, clk->uvdet_slope);

calibrated:
        /* Compute and apply initial DVFS parameters */
        gm20b_dvfs_calc_det_coeff(clk, clk->uv, &clk->dvfs);
        gm20b_dvfs_program_coeff(clk, 0);
        gm20b_dvfs_program_ext_cal(clk, clk->dvfs.dfs_ext_cal);
        gm20b_dvfs_program_coeff(clk, clk->dvfs.dfs_coeff);
        gm20b_dvfs_program_dfs_detection(clk, &clk->new_dvfs);

        return 0;
}

/* Forward declaration to detect speedo >=1 in gm20b_clk_init() */
static const struct nvkm_clk_func gm20b_clk;

static int
gm20b_clk_init(struct nvkm_clk *base)
{
        struct gk20a_clk *clk = gk20a_clk(base);
        struct nvkm_subdev *subdev = &clk->base.subdev;
        struct nvkm_device *device = subdev->device;
        int ret;
        u32 data;

        /* get out from IDDQ */
        nvkm_mask(device, GPCPLL_CFG, GPCPLL_CFG_IDDQ, 0);
        nvkm_rd32(device, GPCPLL_CFG);
        udelay(5);

        nvkm_mask(device, GPC2CLK_OUT, GPC2CLK_OUT_INIT_MASK,
                  GPC2CLK_OUT_INIT_VAL);

        /* Set the global bypass control to VCO */
        nvkm_mask(device, BYPASSCTRL_SYS,
               MASK(BYPASSCTRL_SYS_GPCPLL_WIDTH) << BYPASSCTRL_SYS_GPCPLL_SHIFT,
               0);

        ret = gk20a_clk_setup_slide(clk);
        if (ret)
                return ret;

        /* If not fused, set RAM SVOP PDP data 0x2, and enable fuse override */
        data = nvkm_rd32(device, 0x021944);
        if (!(data & 0x3)) {
                data |= 0x2;
                nvkm_wr32(device, 0x021944, data);

                data = nvkm_rd32(device, 0x021948);
                data |=  0x1;
                nvkm_wr32(device, 0x021948, data);
        }

        /* Disable idle slow down  */
        nvkm_mask(device, 0x20160, 0x003f0000, 0x0);

        /* speedo >= 1? */
        if (clk->base.func == &gm20b_clk) {
                struct gm20b_clk *_clk = gm20b_clk(base);
                struct nvkm_volt *volt = device->volt;

                /* Get current voltage */
                _clk->uv = nvkm_volt_get(volt);

                /* Initialize DVFS */
                ret = gm20b_clk_init_dvfs(_clk);
                if (ret)
                        return ret;
        }

        /* Start with lowest frequency */
        base->func->calc(base, &base->func->pstates[0].base);
        ret = base->func->prog(base);
        if (ret) {
                nvkm_error(subdev, "cannot initialize clock\n");
                return ret;
        }

        return 0;
}

static const struct nvkm_clk_func
gm20b_clk_speedo0 = {
        .init = gm20b_clk_init,
        .fini = gk20a_clk_fini,
        .read = gk20a_clk_read,
        .calc = gk20a_clk_calc,
        .prog = gk20a_clk_prog,
        .tidy = gk20a_clk_tidy,
        .pstates = gm20b_pstates,
        /* Speedo 0 only supports 12 voltages */
        .nr_pstates = ARRAY_SIZE(gm20b_pstates) - 1,
        .domains = {
                { nv_clk_src_crystal, 0xff },
                { nv_clk_src_gpc, 0xff, 0, "core", GK20A_CLK_GPC_MDIV },
                { nv_clk_src_max },
        },
};

static const struct nvkm_clk_func
gm20b_clk = {
        .init = gm20b_clk_init,
        .fini = gm20b_clk_fini,
        .read = gk20a_clk_read,
        .calc = gm20b_clk_calc,
        .prog = gm20b_clk_prog,
        .tidy = gk20a_clk_tidy,
        .pstates = gm20b_pstates,
        .nr_pstates = ARRAY_SIZE(gm20b_pstates),
        .domains = {
                { nv_clk_src_crystal, 0xff },
                { nv_clk_src_gpc, 0xff, 0, "core", GK20A_CLK_GPC_MDIV },
                { nv_clk_src_max },
        },
};

static int
gm20b_clk_new_speedo0(struct nvkm_device *device, enum nvkm_subdev_type type, int inst,
                      struct nvkm_clk **pclk)
{
        struct gk20a_clk *clk;
        int ret;

        clk = kzalloc(sizeof(*clk), GFP_KERNEL);
        if (!clk)
                return -ENOMEM;
        *pclk = &clk->base;

        ret = gk20a_clk_ctor(device, type, inst, &gm20b_clk_speedo0, &gm20b_pllg_params, clk);
        clk->pl_to_div = pl_to_div;
        clk->div_to_pl = div_to_pl;
        return ret;
}

/* FUSE register */
#define FUSE_RESERVED_CALIB0    0x204
#define FUSE_RESERVED_CALIB0_INTERCEPT_FRAC_SHIFT       0
#define FUSE_RESERVED_CALIB0_INTERCEPT_FRAC_WIDTH       4
#define FUSE_RESERVED_CALIB0_INTERCEPT_INT_SHIFT        4
#define FUSE_RESERVED_CALIB0_INTERCEPT_INT_WIDTH        10
#define FUSE_RESERVED_CALIB0_SLOPE_FRAC_SHIFT           14
#define FUSE_RESERVED_CALIB0_SLOPE_FRAC_WIDTH           10
#define FUSE_RESERVED_CALIB0_SLOPE_INT_SHIFT            24
#define FUSE_RESERVED_CALIB0_SLOPE_INT_WIDTH            6
#define FUSE_RESERVED_CALIB0_FUSE_REV_SHIFT             30
#define FUSE_RESERVED_CALIB0_FUSE_REV_WIDTH             2

static int
gm20b_clk_init_fused_params(struct gm20b_clk *clk)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        u32 val = 0;
        u32 rev = 0;

#if IS_ENABLED(CONFIG_ARCH_TEGRA)
        tegra_fuse_readl(FUSE_RESERVED_CALIB0, &val);
        rev = (val >> FUSE_RESERVED_CALIB0_FUSE_REV_SHIFT) &
              MASK(FUSE_RESERVED_CALIB0_FUSE_REV_WIDTH);
#endif

        /* No fused parameters, we will calibrate later */
        if (rev == 0)
                return -EINVAL;

        /* Integer part in mV + fractional part in uV */
        clk->uvdet_slope = ((val >> FUSE_RESERVED_CALIB0_SLOPE_INT_SHIFT) &
                        MASK(FUSE_RESERVED_CALIB0_SLOPE_INT_WIDTH)) * 1000 +
                        ((val >> FUSE_RESERVED_CALIB0_SLOPE_FRAC_SHIFT) &
                        MASK(FUSE_RESERVED_CALIB0_SLOPE_FRAC_WIDTH));

        /* Integer part in mV + fractional part in 100uV */
        clk->uvdet_offs = ((val >> FUSE_RESERVED_CALIB0_INTERCEPT_INT_SHIFT) &
                        MASK(FUSE_RESERVED_CALIB0_INTERCEPT_INT_WIDTH)) * 1000 +
                        ((val >> FUSE_RESERVED_CALIB0_INTERCEPT_FRAC_SHIFT) &
                         MASK(FUSE_RESERVED_CALIB0_INTERCEPT_FRAC_WIDTH)) * 100;

        nvkm_debug(subdev, "fused calibration data: slope %d, offs %d\n",
                   clk->uvdet_slope, clk->uvdet_offs);
        return 0;
}

static int
gm20b_clk_init_safe_fmax(struct gm20b_clk *clk)
{
        struct nvkm_subdev *subdev = &clk->base.base.subdev;
        struct nvkm_volt *volt = subdev->device->volt;
        struct nvkm_pstate *pstates = clk->base.base.func->pstates;
        int nr_pstates = clk->base.base.func->nr_pstates;
        int vmin, id = 0;
        u32 fmax = 0;
        int i;

        /* find lowest voltage we can use */
        vmin = volt->vid[0].uv;
        for (i = 1; i < volt->vid_nr; i++) {
                if (volt->vid[i].uv <= vmin) {
                        vmin = volt->vid[i].uv;
                        id = volt->vid[i].vid;
                }
        }

        /* find max frequency at this voltage */
        for (i = 0; i < nr_pstates; i++)
                if (pstates[i].base.voltage == id)
                        fmax = max(fmax,
                                   pstates[i].base.domain[nv_clk_src_gpc]);

        if (!fmax) {
                nvkm_error(subdev, "failed to evaluate safe fmax\n");
                return -EINVAL;
        }

        /* we are safe at 90% of the max frequency */
        clk->safe_fmax_vmin = fmax * (100 - 10) / 100;
        nvkm_debug(subdev, "safe fmax @ vmin = %u Khz\n", clk->safe_fmax_vmin);

        return 0;
}

int
gm20b_clk_new(struct nvkm_device *device, enum nvkm_subdev_type type, int inst,
              struct nvkm_clk **pclk)
{
        struct nvkm_device_tegra *tdev = device->func->tegra(device);
        struct gm20b_clk *clk;
        struct nvkm_subdev *subdev;
        struct gk20a_clk_pllg_params *clk_params;
        int ret;

        /* Speedo 0 GPUs cannot use noise-aware PLL */
        if (tdev->gpu_speedo_id == 0)
                return gm20b_clk_new_speedo0(device, type, inst, pclk);

        /* Speedo >= 1, use NAPLL */
        clk = kzalloc(sizeof(*clk) + sizeof(*clk_params), GFP_KERNEL);
        if (!clk)
                return -ENOMEM;
        *pclk = &clk->base.base;
        subdev = &clk->base.base.subdev;

        /* duplicate the clock parameters since we will patch them below */
        clk_params = (void *) (clk + 1);
        *clk_params = gm20b_pllg_params;
        ret = gk20a_clk_ctor(device, type, inst, &gm20b_clk, clk_params, &clk->base);
        if (ret)
                return ret;

        /*
         * NAPLL can only work with max_u, clamp the m range so
         * gk20a_pllg_calc_mnp always uses it
         */
        clk_params->max_m = clk_params->min_m = DIV_ROUND_UP(clk_params->max_u,
                                                (clk->base.parent_rate / KHZ));
        if (clk_params->max_m == 0) {
                nvkm_warn(subdev, "cannot use NAPLL, using legacy clock...\n");
                kfree(clk);
                return gm20b_clk_new_speedo0(device, type, inst, pclk);
        }

        clk->base.pl_to_div = pl_to_div;
        clk->base.div_to_pl = div_to_pl;

        clk->dvfs_params = &gm20b_dvfs_params;

        ret = gm20b_clk_init_fused_params(clk);
        /*
         * we will calibrate during init - should never happen on
         * prod parts
         */
        if (ret)
                nvkm_warn(subdev, "no fused calibration parameters\n");

        ret = gm20b_clk_init_safe_fmax(clk);
        if (ret)
                return ret;

        return 0;
}