/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2019 Intel Corporation
 */

#include <linux/pm_runtime.h>

#include "i915_drv.h"
#include "i915_vgpu.h"
#include "intel_gt.h"
#include "intel_gt_pm.h"
#include "intel_rc6.h"
#include "intel_sideband.h"

/**
 * DOC: RC6
 *
 * RC6 is a special power stage which allows the GPU to enter an very
 * low-voltage mode when idle, using down to 0V while at this stage.  This
 * stage is entered automatically when the GPU is idle when RC6 support is
 * enabled, and as soon as new workload arises GPU wakes up automatically as
 * well.
 *
 * There are different RC6 modes available in Intel GPU, which differentiate
 * among each other with the latency required to enter and leave RC6 and
 * voltage consumed by the GPU in different states.
 *
 * The combination of the following flags define which states GPU is allowed
 * to enter, while RC6 is the normal RC6 state, RC6p is the deep RC6, and
 * RC6pp is deepest RC6. Their support by hardware varies according to the
 * GPU, BIOS, chipset and platform. RC6 is usually the safest one and the one
 * which brings the most power savings; deeper states save more power, but
 * require higher latency to switch to and wake up.
 */

static struct intel_gt *rc6_to_gt(struct intel_rc6 *rc6)
{
        return container_of(rc6, struct intel_gt, rc6);
}

static struct intel_uncore *rc6_to_uncore(struct intel_rc6 *rc)
{
        return rc6_to_gt(rc)->uncore;
}

static struct drm_i915_private *rc6_to_i915(struct intel_rc6 *rc)
{
        return rc6_to_gt(rc)->i915;
}

static void set(struct intel_uncore *uncore, i915_reg_t reg, u32 val)
{
        intel_uncore_write_fw(uncore, reg, val);
}

static void gen11_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_gt *gt = rc6_to_gt(rc6);
        struct intel_uncore *uncore = gt->uncore;
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        u32 pg_enable;
        int i;

        /* 2b: Program RC6 thresholds.*/
        set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 54 << 16 | 85);
        set(uncore, GEN10_MEDIA_WAKE_RATE_LIMIT, 150);

        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000); /* 12500 * 1280ns */
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25); /* 25 * 1280ns */
        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);

        set(uncore, GUC_MAX_IDLE_COUNT, 0xA);

        set(uncore, GEN6_RC_SLEEP, 0);

        set(uncore, GEN6_RC6_THRESHOLD, 50000); /* 50/125ms per EI */

        /*
         * 2c: Program Coarse Power Gating Policies.
         *
         * Bspec's guidance is to use 25us (really 25 * 1280ns) here. What we
         * use instead is a more conservative estimate for the maximum time
         * it takes us to service a CS interrupt and submit a new ELSP - that
         * is the time which the GPU is idle waiting for the CPU to select the
         * next request to execute. If the idle hysteresis is less than that
         * interrupt service latency, the hardware will automatically gate
         * the power well and we will then incur the wake up cost on top of
         * the service latency. A similar guide from plane_state is that we
         * do not want the enable hysteresis to less than the wakeup latency.
         *
         * igt/gem_exec_nop/sequential provides a rough estimate for the
         * service latency, and puts it under 10us for Icelake, similar to
         * Broadwell+, To be conservative, we want to factor in a context
         * switch on top (due to ksoftirqd).
         */
        set(uncore, GEN9_MEDIA_PG_IDLE_HYSTERESIS, 60);
        set(uncore, GEN9_RENDER_PG_IDLE_HYSTERESIS, 60);

        /* 3a: Enable RC6 */
        rc6->ctl_enable =
                GEN6_RC_CTL_HW_ENABLE |
                GEN6_RC_CTL_RC6_ENABLE |
                GEN6_RC_CTL_EI_MODE(1);

        pg_enable =
                GEN9_RENDER_PG_ENABLE |
                GEN9_MEDIA_PG_ENABLE |
                GEN11_MEDIA_SAMPLER_PG_ENABLE;

        if (INTEL_GEN(gt->i915) >= 12) {
                for (i = 0; i < I915_MAX_VCS; i++)
                        if (HAS_ENGINE(gt, _VCS(i)))
                                pg_enable |= (VDN_HCP_POWERGATE_ENABLE(i) |
                                              VDN_MFX_POWERGATE_ENABLE(i));
        }

        set(uncore, GEN9_PG_ENABLE, pg_enable);
}

static void gen9_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /* 2b: Program RC6 thresholds.*/
        if (INTEL_GEN(rc6_to_i915(rc6)) >= 10) {
                set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 54 << 16 | 85);
                set(uncore, GEN10_MEDIA_WAKE_RATE_LIMIT, 150);
        } else if (IS_SKYLAKE(rc6_to_i915(rc6))) {
                /*
                 * WaRsDoubleRc6WrlWithCoarsePowerGating:skl Doubling WRL only
                 * when CPG is enabled
                 */
                set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 108 << 16);
        } else {
                set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 54 << 16);
        }

        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000); /* 12500 * 1280ns */
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25); /* 25 * 1280ns */
        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);

        set(uncore, GUC_MAX_IDLE_COUNT, 0xA);

        set(uncore, GEN6_RC_SLEEP, 0);

        /*
         * 2c: Program Coarse Power Gating Policies.
         *
         * Bspec's guidance is to use 25us (really 25 * 1280ns) here. What we
         * use instead is a more conservative estimate for the maximum time
         * it takes us to service a CS interrupt and submit a new ELSP - that
         * is the time which the GPU is idle waiting for the CPU to select the
         * next request to execute. If the idle hysteresis is less than that
         * interrupt service latency, the hardware will automatically gate
         * the power well and we will then incur the wake up cost on top of
         * the service latency. A similar guide from plane_state is that we
         * do not want the enable hysteresis to less than the wakeup latency.
         *
         * igt/gem_exec_nop/sequential provides a rough estimate for the
         * service latency, and puts it around 10us for Broadwell (and other
         * big core) and around 40us for Broxton (and other low power cores).
         * [Note that for legacy ringbuffer submission, this is less than 1us!]
         * However, the wakeup latency on Broxton is closer to 100us. To be
         * conservative, we have to factor in a context switch on top (due
         * to ksoftirqd).
         */
        set(uncore, GEN9_MEDIA_PG_IDLE_HYSTERESIS, 250);
        set(uncore, GEN9_RENDER_PG_IDLE_HYSTERESIS, 250);

        /* 3a: Enable RC6 */
        set(uncore, GEN6_RC6_THRESHOLD, 37500); /* 37.5/125ms per EI */


        rc6->ctl_enable =
                GEN6_RC_CTL_HW_ENABLE |
                GEN6_RC_CTL_RC6_ENABLE |
                GEN6_RC_CTL_EI_MODE(1);

        /*
         * WaRsDisableCoarsePowerGating:skl,cnl
         *   - Render/Media PG need to be disabled with RC6.
         */
        if (!NEEDS_WaRsDisableCoarsePowerGating(rc6_to_i915(rc6)))
                set(uncore, GEN9_PG_ENABLE,
                    GEN9_RENDER_PG_ENABLE | GEN9_MEDIA_PG_ENABLE);
}

static void gen8_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /* 2b: Program RC6 thresholds.*/
        set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 40 << 16);
        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000); /* 12500 * 1280ns */
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25); /* 25 * 1280ns */
        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);
        set(uncore, GEN6_RC_SLEEP, 0);
        set(uncore, GEN6_RC6_THRESHOLD, 625); /* 800us/1.28 for TO */

        /* 3: Enable RC6 */
        rc6->ctl_enable =
            GEN6_RC_CTL_HW_ENABLE |
            GEN7_RC_CTL_TO_MODE |
            GEN6_RC_CTL_RC6_ENABLE;
}

static void gen6_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        u32 rc6vids, rc6_mask;
        int ret;

        set(uncore, GEN6_RC1_WAKE_RATE_LIMIT, 1000 << 16);
        set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 40 << 16 | 30);
        set(uncore, GEN6_RC6pp_WAKE_RATE_LIMIT, 30);
        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000);
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25);

        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);

        set(uncore, GEN6_RC_SLEEP, 0);
        set(uncore, GEN6_RC1e_THRESHOLD, 1000);
        set(uncore, GEN6_RC6_THRESHOLD, 50000);
        set(uncore, GEN6_RC6p_THRESHOLD, 150000);
        set(uncore, GEN6_RC6pp_THRESHOLD, 64000); /* unused */

        /* We don't use those on Haswell */
        rc6_mask = GEN6_RC_CTL_RC6_ENABLE;
        if (HAS_RC6p(i915))
                rc6_mask |= GEN6_RC_CTL_RC6p_ENABLE;
        if (HAS_RC6pp(i915))
                rc6_mask |= GEN6_RC_CTL_RC6pp_ENABLE;
        rc6->ctl_enable =
            rc6_mask |
            GEN6_RC_CTL_EI_MODE(1) |
            GEN6_RC_CTL_HW_ENABLE;

        rc6vids = 0;
        ret = sandybridge_pcode_read(i915, GEN6_PCODE_READ_RC6VIDS,
                                     &rc6vids, NULL);
        if (IS_GEN(i915, 6) && ret) {
                drm_dbg(&i915->drm, "Couldn't check for BIOS workaround\n");
        } else if (IS_GEN(i915, 6) &&
                   (GEN6_DECODE_RC6_VID(rc6vids & 0xff) < 450)) {
                drm_dbg(&i915->drm,
                        "You should update your BIOS. Correcting minimum rc6 voltage (%dmV->%dmV)\n",
                        GEN6_DECODE_RC6_VID(rc6vids & 0xff), 450);
                rc6vids &= 0xffff00;
                rc6vids |= GEN6_ENCODE_RC6_VID(450);
                ret = sandybridge_pcode_write(i915, GEN6_PCODE_WRITE_RC6VIDS, rc6vids);
                if (ret)
                        drm_err(&i915->drm,
                                "Couldn't fix incorrect rc6 voltage\n");
        }
}

/* Check that the pcbr address is not empty. */
static int chv_rc6_init(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        resource_size_t pctx_paddr, paddr;
        resource_size_t pctx_size = 32 * SZ_1K;
        u32 pcbr;

        pcbr = intel_uncore_read(uncore, VLV_PCBR);
        if ((pcbr >> VLV_PCBR_ADDR_SHIFT) == 0) {
                drm_dbg(&i915->drm, "BIOS didn't set up PCBR, fixing up\n");
                paddr = i915->dsm.end + 1 - pctx_size;
                GEM_BUG_ON(paddr > U32_MAX);

                pctx_paddr = (paddr & ~4095);
                intel_uncore_write(uncore, VLV_PCBR, pctx_paddr);
        }

        return 0;
}

static int vlv_rc6_init(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct drm_i915_gem_object *pctx;
        resource_size_t pctx_paddr;
        resource_size_t pctx_size = 24 * SZ_1K;
        u32 pcbr;

        pcbr = intel_uncore_read(uncore, VLV_PCBR);
        if (pcbr) {
                /* BIOS set it up already, grab the pre-alloc'd space */
                resource_size_t pcbr_offset;

                pcbr_offset = (pcbr & ~4095) - i915->dsm.start;
                pctx = i915_gem_object_create_stolen_for_preallocated(i915,
                                                                      pcbr_offset,
                                                                      pctx_size);
                if (IS_ERR(pctx))
                        return PTR_ERR(pctx);

                goto out;
        }

        drm_dbg(&i915->drm, "BIOS didn't set up PCBR, fixing up\n");

        /*
         * From the Gunit register HAS:
         * The Gfx driver is expected to program this register and ensure
         * proper allocation within Gfx stolen memory.  For example, this
         * register should be programmed such than the PCBR range does not
         * overlap with other ranges, such as the frame buffer, protected
         * memory, or any other relevant ranges.
         */
        pctx = i915_gem_object_create_stolen(i915, pctx_size);
        if (IS_ERR(pctx)) {
                drm_dbg(&i915->drm,
                        "not enough stolen space for PCTX, disabling\n");
                return PTR_ERR(pctx);
        }

        GEM_BUG_ON(range_overflows_end_t(u64,
                                         i915->dsm.start,
                                         pctx->stolen->start,
                                         U32_MAX));
        pctx_paddr = i915->dsm.start + pctx->stolen->start;
        intel_uncore_write(uncore, VLV_PCBR, pctx_paddr);

out:
        rc6->pctx = pctx;
        return 0;
}

static void chv_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /* 2a: Program RC6 thresholds.*/
        set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 40 << 16);
        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000); /* 12500 * 1280ns */
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25); /* 25 * 1280ns */

        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);
        set(uncore, GEN6_RC_SLEEP, 0);

        /* TO threshold set to 500 us (0x186 * 1.28 us) */
        set(uncore, GEN6_RC6_THRESHOLD, 0x186);

        /* Allows RC6 residency counter to work */
        set(uncore, VLV_COUNTER_CONTROL,
            _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH |
                               VLV_MEDIA_RC6_COUNT_EN |
                               VLV_RENDER_RC6_COUNT_EN));

        /* 3: Enable RC6 */
        rc6->ctl_enable = GEN7_RC_CTL_TO_MODE;
}

static void vlv_rc6_enable(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        set(uncore, GEN6_RC6_WAKE_RATE_LIMIT, 0x00280000);
        set(uncore, GEN6_RC_EVALUATION_INTERVAL, 125000);
        set(uncore, GEN6_RC_IDLE_HYSTERSIS, 25);

        for_each_engine(engine, rc6_to_gt(rc6), id)
                set(uncore, RING_MAX_IDLE(engine->mmio_base), 10);

        set(uncore, GEN6_RC6_THRESHOLD, 0x557);

        /* Allows RC6 residency counter to work */
        set(uncore, VLV_COUNTER_CONTROL,
            _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH |
                               VLV_MEDIA_RC0_COUNT_EN |
                               VLV_RENDER_RC0_COUNT_EN |
                               VLV_MEDIA_RC6_COUNT_EN |
                               VLV_RENDER_RC6_COUNT_EN));

        rc6->ctl_enable =
            GEN7_RC_CTL_TO_MODE | VLV_RC_CTL_CTX_RST_PARALLEL;
}

static bool bxt_check_bios_rc6_setup(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        u32 rc6_ctx_base, rc_ctl, rc_sw_target;
        bool enable_rc6 = true;

        rc_ctl = intel_uncore_read(uncore, GEN6_RC_CONTROL);
        rc_sw_target = intel_uncore_read(uncore, GEN6_RC_STATE);
        rc_sw_target &= RC_SW_TARGET_STATE_MASK;
        rc_sw_target >>= RC_SW_TARGET_STATE_SHIFT;
        drm_dbg(&i915->drm, "BIOS enabled RC states: "
                         "HW_CTRL %s HW_RC6 %s SW_TARGET_STATE %x\n",
                         onoff(rc_ctl & GEN6_RC_CTL_HW_ENABLE),
                         onoff(rc_ctl & GEN6_RC_CTL_RC6_ENABLE),
                         rc_sw_target);

        if (!(intel_uncore_read(uncore, RC6_LOCATION) & RC6_CTX_IN_DRAM)) {
                drm_dbg(&i915->drm, "RC6 Base location not set properly.\n");
                enable_rc6 = false;
        }

        /*
         * The exact context size is not known for BXT, so assume a page size
         * for this check.
         */
        rc6_ctx_base =
                intel_uncore_read(uncore, RC6_CTX_BASE) & RC6_CTX_BASE_MASK;
        if (!(rc6_ctx_base >= i915->dsm_reserved.start &&
              rc6_ctx_base + PAGE_SIZE < i915->dsm_reserved.end)) {
                drm_dbg(&i915->drm, "RC6 Base address not as expected.\n");
                enable_rc6 = false;
        }

        if (!((intel_uncore_read(uncore, PWRCTX_MAXCNT_RCSUNIT) & IDLE_TIME_MASK) > 1 &&
              (intel_uncore_read(uncore, PWRCTX_MAXCNT_VCSUNIT0) & IDLE_TIME_MASK) > 1 &&
              (intel_uncore_read(uncore, PWRCTX_MAXCNT_BCSUNIT) & IDLE_TIME_MASK) > 1 &&
              (intel_uncore_read(uncore, PWRCTX_MAXCNT_VECSUNIT) & IDLE_TIME_MASK) > 1)) {
                drm_dbg(&i915->drm,
                        "Engine Idle wait time not set properly.\n");
                enable_rc6 = false;
        }

        if (!intel_uncore_read(uncore, GEN8_PUSHBUS_CONTROL) ||
            !intel_uncore_read(uncore, GEN8_PUSHBUS_ENABLE) ||
            !intel_uncore_read(uncore, GEN8_PUSHBUS_SHIFT)) {
                drm_dbg(&i915->drm, "Pushbus not setup properly.\n");
                enable_rc6 = false;
        }

        if (!intel_uncore_read(uncore, GEN6_GFXPAUSE)) {
                drm_dbg(&i915->drm, "GFX pause not setup properly.\n");
                enable_rc6 = false;
        }

        if (!intel_uncore_read(uncore, GEN8_MISC_CTRL0)) {
                drm_dbg(&i915->drm, "GPM control not setup properly.\n");
                enable_rc6 = false;
        }

        return enable_rc6;
}

static bool rc6_supported(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);

        if (!HAS_RC6(i915))
                return false;

        if (intel_vgpu_active(i915))
                return false;

        if (is_mock_gt(rc6_to_gt(rc6)))
                return false;

        if (IS_GEN9_LP(i915) && !bxt_check_bios_rc6_setup(rc6)) {
                drm_notice(&i915->drm,
                           "RC6 and powersaving disabled by BIOS\n");
                return false;
        }

        return true;
}

static void rpm_get(struct intel_rc6 *rc6)
{
        GEM_BUG_ON(rc6->wakeref);
        pm_runtime_get_sync(&rc6_to_i915(rc6)->drm.pdev->dev);
        rc6->wakeref = true;
}

static void rpm_put(struct intel_rc6 *rc6)
{
        GEM_BUG_ON(!rc6->wakeref);
        pm_runtime_put(&rc6_to_i915(rc6)->drm.pdev->dev);
        rc6->wakeref = false;
}

static bool pctx_corrupted(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);

        if (!NEEDS_RC6_CTX_CORRUPTION_WA(i915))
                return false;

        if (intel_uncore_read(rc6_to_uncore(rc6), GEN8_RC6_CTX_INFO))
                return false;

        drm_notice(&i915->drm,
                   "RC6 context corruption, disabling runtime power management\n");
        return true;
}

static void __intel_rc6_disable(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        struct intel_uncore *uncore = rc6_to_uncore(rc6);

        intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);
        if (INTEL_GEN(i915) >= 9)
                set(uncore, GEN9_PG_ENABLE, 0);
        set(uncore, GEN6_RC_CONTROL, 0);
        set(uncore, GEN6_RC_STATE, 0);
        intel_uncore_forcewake_put(uncore, FORCEWAKE_ALL);
}

void intel_rc6_init(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        int err;

        /* Disable runtime-pm until we can save the GPU state with rc6 pctx */
        rpm_get(rc6);

        if (!rc6_supported(rc6))
                return;

        if (IS_CHERRYVIEW(i915))
                err = chv_rc6_init(rc6);
        else if (IS_VALLEYVIEW(i915))
                err = vlv_rc6_init(rc6);
        else
                err = 0;

        /* Sanitize rc6, ensure it is disabled before we are ready. */
        __intel_rc6_disable(rc6);

        rc6->supported = err == 0;
}

void intel_rc6_sanitize(struct intel_rc6 *rc6)
{
        memset(rc6->prev_hw_residency, 0, sizeof(rc6->prev_hw_residency));

        if (rc6->enabled) { /* unbalanced suspend/resume */
                rpm_get(rc6);
                rc6->enabled = false;
        }

        if (rc6->supported)
                __intel_rc6_disable(rc6);
}

void intel_rc6_enable(struct intel_rc6 *rc6)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        struct intel_uncore *uncore = rc6_to_uncore(rc6);

        if (!rc6->supported)
                return;

        GEM_BUG_ON(rc6->enabled);

        intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);

        if (IS_CHERRYVIEW(i915))
                chv_rc6_enable(rc6);
        else if (IS_VALLEYVIEW(i915))
                vlv_rc6_enable(rc6);
        else if (INTEL_GEN(i915) >= 11)
                gen11_rc6_enable(rc6);
        else if (INTEL_GEN(i915) >= 9)
                gen9_rc6_enable(rc6);
        else if (IS_BROADWELL(i915))
                gen8_rc6_enable(rc6);
        else if (INTEL_GEN(i915) >= 6)
                gen6_rc6_enable(rc6);

        rc6->manual = rc6->ctl_enable & GEN6_RC_CTL_RC6_ENABLE;
        if (NEEDS_RC6_CTX_CORRUPTION_WA(i915))
                rc6->ctl_enable = 0;

        intel_uncore_forcewake_put(uncore, FORCEWAKE_ALL);

        if (unlikely(pctx_corrupted(rc6)))
                return;

        /* rc6 is ready, runtime-pm is go! */
        rpm_put(rc6);
        rc6->enabled = true;
}

void intel_rc6_unpark(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);

        if (!rc6->enabled)
                return;

        /* Restore HW timers for automatic RC6 entry while busy */
        set(uncore, GEN6_RC_CONTROL, rc6->ctl_enable);
}

void intel_rc6_park(struct intel_rc6 *rc6)
{
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        unsigned int target;

        if (!rc6->enabled)
                return;

        if (unlikely(pctx_corrupted(rc6))) {
                intel_rc6_disable(rc6);
                return;
        }

        if (!rc6->manual)
                return;

        /* Turn off the HW timers and go directly to rc6 */
        set(uncore, GEN6_RC_CONTROL, GEN6_RC_CTL_RC6_ENABLE);

        if (HAS_RC6pp(rc6_to_i915(rc6)))
                target = 0x6; /* deepest rc6 */
        else if (HAS_RC6p(rc6_to_i915(rc6)))
                target = 0x5; /* deep rc6 */
        else
                target = 0x4; /* normal rc6 */
        set(uncore, GEN6_RC_STATE, target << RC_SW_TARGET_STATE_SHIFT);
}

void intel_rc6_disable(struct intel_rc6 *rc6)
{
        if (!rc6->enabled)
                return;

        rpm_get(rc6);
        rc6->enabled = false;

        __intel_rc6_disable(rc6);
}

void intel_rc6_fini(struct intel_rc6 *rc6)
{
        struct drm_i915_gem_object *pctx;

        intel_rc6_disable(rc6);

        pctx = fetch_and_zero(&rc6->pctx);
        if (pctx)
                i915_gem_object_put(pctx);

        if (rc6->wakeref)
                rpm_put(rc6);
}

static u64 vlv_residency_raw(struct intel_uncore *uncore, const i915_reg_t reg)
{
        u32 lower, upper, tmp;
        int loop = 2;

        /*
         * The register accessed do not need forcewake. We borrow
         * uncore lock to prevent concurrent access to range reg.
         */
        lockdep_assert_held(&uncore->lock);

        /*
         * vlv and chv residency counters are 40 bits in width.
         * With a control bit, we can choose between upper or lower
         * 32bit window into this counter.
         *
         * Although we always use the counter in high-range mode elsewhere,
         * userspace may attempt to read the value before rc6 is initialised,
         * before we have set the default VLV_COUNTER_CONTROL value. So always
         * set the high bit to be safe.
         */
        set(uncore, VLV_COUNTER_CONTROL,
            _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH));
        upper = intel_uncore_read_fw(uncore, reg);
        do {
                tmp = upper;

                set(uncore, VLV_COUNTER_CONTROL,
                    _MASKED_BIT_DISABLE(VLV_COUNT_RANGE_HIGH));
                lower = intel_uncore_read_fw(uncore, reg);

                set(uncore, VLV_COUNTER_CONTROL,
                    _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH));
                upper = intel_uncore_read_fw(uncore, reg);
        } while (upper != tmp && --loop);

        /*
         * Everywhere else we always use VLV_COUNTER_CONTROL with the
         * VLV_COUNT_RANGE_HIGH bit set - so it is safe to leave it set
         * now.
         */

        return lower | (u64)upper << 8;
}

u64 intel_rc6_residency_ns(struct intel_rc6 *rc6, const i915_reg_t reg)
{
        struct drm_i915_private *i915 = rc6_to_i915(rc6);
        struct intel_uncore *uncore = rc6_to_uncore(rc6);
        u64 time_hw, prev_hw, overflow_hw;
        unsigned int fw_domains;
        unsigned long flags;
        unsigned int i;
        u32 mul, div;

        if (!rc6->supported)
                return 0;

        /*
         * Store previous hw counter values for counter wrap-around handling.
         *
         * There are only four interesting registers and they live next to each
         * other so we can use the relative address, compared to the smallest
         * one as the index into driver storage.
         */
        i = (i915_mmio_reg_offset(reg) -
             i915_mmio_reg_offset(GEN6_GT_GFX_RC6_LOCKED)) / sizeof(u32);
        if (drm_WARN_ON_ONCE(&i915->drm, i >= ARRAY_SIZE(rc6->cur_residency)))
                return 0;

        fw_domains = intel_uncore_forcewake_for_reg(uncore, reg, FW_REG_READ);

        spin_lock_irqsave(&uncore->lock, flags);
        intel_uncore_forcewake_get__locked(uncore, fw_domains);

        /* On VLV and CHV, residency time is in CZ units rather than 1.28us */
        if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915)) {
                mul = 1000000;
                div = i915->czclk_freq;
                overflow_hw = BIT_ULL(40);
                time_hw = vlv_residency_raw(uncore, reg);
        } else {
                /* 833.33ns units on Gen9LP, 1.28us elsewhere. */
                if (IS_GEN9_LP(i915)) {
                        mul = 10000;
                        div = 12;
                } else {
                        mul = 1280;
                        div = 1;
                }

                overflow_hw = BIT_ULL(32);
                time_hw = intel_uncore_read_fw(uncore, reg);
        }

        /*
         * Counter wrap handling.
         *
         * But relying on a sufficient frequency of queries otherwise counters
         * can still wrap.
         */
        prev_hw = rc6->prev_hw_residency[i];
        rc6->prev_hw_residency[i] = time_hw;

        /* RC6 delta from last sample. */
        if (time_hw >= prev_hw)
                time_hw -= prev_hw;
        else
                time_hw += overflow_hw - prev_hw;

        /* Add delta to RC6 extended raw driver copy. */
        time_hw += rc6->cur_residency[i];
        rc6->cur_residency[i] = time_hw;

        intel_uncore_forcewake_put__locked(uncore, fw_domains);
        spin_unlock_irqrestore(&uncore->lock, flags);

        return mul_u64_u32_div(time_hw, mul, div);
}

u64 intel_rc6_residency_us(struct intel_rc6 *rc6, i915_reg_t reg)
{
        return DIV_ROUND_UP_ULL(intel_rc6_residency_ns(rc6, reg), 1000);
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_rc6.c"
#endif