drm/i915: add functions to disable and restore LCPLL

For now there are no callers, but these functions are going to be
needed for the code that allows Package C8+. Other future features may
also require this code.

Also merge the commit which introduced assert_can_disable_lcpll and
had the following commit message:

Most of the hardware needs to be disabled before LCPLL is disabled, so
let's add a function to assert some of items listed in the "Display
Sequences for LCPLL disabling" documentation.

The idea is that hsw_disable_lcpll should not disable the hardware,
the callers need to take care of calling hsw_disable_lcpll only once
everything is already disabled.

v2: - Rebase.
    - Fix D_COMP wait timeout.
v3: - Use wait_for_atomic_use (Ben)
    - Remove/add a useless/needed POSTING_READ (Ben)
    - Early return in case LCPLL is already restored (Ben)
    - Add ndelay(100) (Ben)
v4: - Merge the commit that added assert_can_disable_lcpll (Ben)
    - Add interrupt assertions (Ben)

Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Fix compile fail since there's no HAS_LP_PCH yet.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 136 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 26b49d8d781c..32024dadccee 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5925,6 +5925,142 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
         return true;
 }
 
+static void assert_can_disable_lcpll(struct drm_i915_private *dev_priv)
+{
+        struct drm_device *dev = dev_priv->dev;
+        struct intel_ddi_plls *plls = &dev_priv->ddi_plls;
+        struct intel_crtc *crtc;
+        unsigned long irqflags;
+        uint32_t val, pch_hpd_mask;
+
+        pch_hpd_mask = SDE_PORTB_HOTPLUG_CPT | SDE_PORTC_HOTPLUG_CPT;
+        if (!(dev_priv->pch_id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE))
+                pch_hpd_mask |= SDE_PORTD_HOTPLUG_CPT | SDE_CRT_HOTPLUG_CPT;
+
+        list_for_each_entry(crtc, &dev->mode_config.crtc_list, base.head)
+                WARN(crtc->base.enabled, "CRTC for pipe %c enabled\n",
+                     pipe_name(crtc->pipe));
+
+        WARN(I915_READ(HSW_PWR_WELL_DRIVER), "Power well on\n");
+        WARN(plls->spll_refcount, "SPLL enabled\n");
+        WARN(plls->wrpll1_refcount, "WRPLL1 enabled\n");
+        WARN(plls->wrpll2_refcount, "WRPLL2 enabled\n");
+        WARN(I915_READ(PCH_PP_STATUS) & PP_ON, "Panel power on\n");
+        WARN(I915_READ(BLC_PWM_CPU_CTL2) & BLM_PWM_ENABLE,
+             "CPU PWM1 enabled\n");
+        WARN(I915_READ(HSW_BLC_PWM2_CTL) & BLM_PWM_ENABLE,
+             "CPU PWM2 enabled\n");
+        WARN(I915_READ(BLC_PWM_PCH_CTL1) & BLM_PCH_PWM_ENABLE,
+             "PCH PWM1 enabled\n");
+        WARN(I915_READ(UTIL_PIN_CTL) & UTIL_PIN_ENABLE,
+             "Utility pin enabled\n");
+        WARN(I915_READ(PCH_GTC_CTL) & PCH_GTC_ENABLE, "PCH GTC enabled\n");
+
+        spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+        val = I915_READ(DEIMR);
+        WARN((val & ~DE_PCH_EVENT_IVB) != val,
+             "Unexpected DEIMR bits enabled: 0x%x\n", val);
+        val = I915_READ(SDEIMR);
+        WARN((val & ~pch_hpd_mask) != val,
+             "Unexpected SDEIMR bits enabled: 0x%x\n", val);
+        spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+}
+
+/*
+ * This function implements pieces of two sequences from BSpec:
+ * - Sequence for display software to disable LCPLL
+ * - Sequence for display software to allow package C8+
+ * The steps implemented here are just the steps that actually touch the LCPLL
+ * register. Callers should take care of disabling all the display engine
+ * functions, doing the mode unset, fixing interrupts, etc.
+ */
+void hsw_disable_lcpll(struct drm_i915_private *dev_priv,
+                       bool switch_to_fclk, bool allow_power_down)
+{
+        uint32_t val;
+
+        assert_can_disable_lcpll(dev_priv);
+
+        val = I915_READ(LCPLL_CTL);
+
+        if (switch_to_fclk) {
+                val |= LCPLL_CD_SOURCE_FCLK;
+                I915_WRITE(LCPLL_CTL, val);
+
+                if (wait_for_atomic_us(I915_READ(LCPLL_CTL) &
+                                       LCPLL_CD_SOURCE_FCLK_DONE, 1))
+                        DRM_ERROR("Switching to FCLK failed\n");
+
+                val = I915_READ(LCPLL_CTL);
+        }
+
+        val |= LCPLL_PLL_DISABLE;
+        I915_WRITE(LCPLL_CTL, val);
+        POSTING_READ(LCPLL_CTL);
+
+        if (wait_for((I915_READ(LCPLL_CTL) & LCPLL_PLL_LOCK) == 0, 1))
+                DRM_ERROR("LCPLL still locked\n");
+
+        val = I915_READ(D_COMP);
+        val |= D_COMP_COMP_DISABLE;
+        I915_WRITE(D_COMP, val);
+        POSTING_READ(D_COMP);
+        ndelay(100);
+
+        if (wait_for((I915_READ(D_COMP) & D_COMP_RCOMP_IN_PROGRESS) == 0, 1))
+                DRM_ERROR("D_COMP RCOMP still in progress\n");
+
+        if (allow_power_down) {
+                val = I915_READ(LCPLL_CTL);
+                val |= LCPLL_POWER_DOWN_ALLOW;
+                I915_WRITE(LCPLL_CTL, val);
+                POSTING_READ(LCPLL_CTL);
+        }
+}
+
+/*
+ * Fully restores LCPLL, disallowing power down and switching back to LCPLL
+ * source.
+ */
+void hsw_restore_lcpll(struct drm_i915_private *dev_priv)
+{
+        uint32_t val;
+
+        val = I915_READ(LCPLL_CTL);
+
+        if ((val & (LCPLL_PLL_LOCK | LCPLL_PLL_DISABLE | LCPLL_CD_SOURCE_FCLK |
+                    LCPLL_POWER_DOWN_ALLOW)) == LCPLL_PLL_LOCK)
+                return;
+
+        if (val & LCPLL_POWER_DOWN_ALLOW) {
+                val &= ~LCPLL_POWER_DOWN_ALLOW;
+                I915_WRITE(LCPLL_CTL, val);
+        }
+
+        val = I915_READ(D_COMP);
+        val |= D_COMP_COMP_FORCE;
+        val &= ~D_COMP_COMP_DISABLE;
+        I915_WRITE(D_COMP, val);
+        I915_READ(D_COMP);
+
+        val = I915_READ(LCPLL_CTL);
+        val &= ~LCPLL_PLL_DISABLE;
+        I915_WRITE(LCPLL_CTL, val);
+
+        if (wait_for(I915_READ(LCPLL_CTL) & LCPLL_PLL_LOCK, 5))
+                DRM_ERROR("LCPLL not locked yet\n");
+
+        if (val & LCPLL_CD_SOURCE_FCLK) {
+                val = I915_READ(LCPLL_CTL);
+                val &= ~LCPLL_CD_SOURCE_FCLK;
+                I915_WRITE(LCPLL_CTL, val);
+
+                if (wait_for_atomic_us((I915_READ(LCPLL_CTL) &
+                                        LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1))
+                        DRM_ERROR("Switching back to LCPLL failed\n");
+        }
+}
+
 static void haswell_modeset_global_resources(struct drm_device *dev)
 {
         bool enable = false;