drm/i915/cnl: Enable wrpll computation for CNL

Enable wrpll computation for Cannonlake platform to support
pll's required for HDMI output. The patch contains the following features

- compute Cannonlake port clock programming
  dividers P, Q, and K.
- compute PLL parameters for Cannonlake. These parameters
  set the values on DPLL registers.
- find the register values to program wrpll for Cannonlake.
  The reference clock can be either 19.2MHz or 24MHz.

v2: rebase
v3: squash wrpll patches into one (Rodrigo)
v4: switch order of getting even dividers (Paulo)
    update divider register values for PDiv and KDiv (Paulo)
    update wrpll computation algorithm (Paulo)
v5: Remove ref clock division by 1000. (Rodrigo)
v6: Rodrigo rebasing on top of latest code.

Signed-off-by: Kahola, Mika <mika.kahola@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1497047175-27250-18-git-send-email-rodrigo.vivi@intel.com

diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index 903c38d..8e669b6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2126,17 +2126,153 @@ out:
        return ret;
 }
 
+static void cnl_wrpll_get_multipliers(unsigned int bestdiv,
+                                     unsigned int *pdiv,
+                                     unsigned int *qdiv,
+                                     unsigned int *kdiv)
+{
+       /* even dividers */
+       if (bestdiv % 2 == 0) {
+               if (bestdiv == 2) {
+                       *pdiv = 2;
+                       *qdiv = 1;
+                       *kdiv = 1;
+               } else if (bestdiv % 4 == 0) {
+                       *pdiv = 2;
+                       *qdiv = bestdiv / 4;
+                       *kdiv = 2;
+               } else if (bestdiv % 6 == 0) {
+                       *pdiv = 3;
+                       *qdiv = bestdiv / 6;
+                       *kdiv = 2;
+               } else if (bestdiv % 5 == 0) {
+                       *pdiv = 5;
+                       *qdiv = bestdiv / 10;
+                       *kdiv = 2;
+               } else if (bestdiv % 14 == 0) {
+                       *pdiv = 7;
+                       *qdiv = bestdiv / 14;
+                       *kdiv = 2;
+               }
+       } else {
+               if (bestdiv == 3 || bestdiv == 5 || bestdiv == 7) {
+                       *pdiv = bestdiv;
+                       *qdiv = 1;
+                       *kdiv = 1;
+               } else { /* 9, 15, 21 */
+                       *pdiv = bestdiv / 3;
+                       *qdiv = 1;
+                       *kdiv = 3;
+               }
+       }
+}
+
+static void cnl_wrpll_params_populate(struct skl_wrpll_params *params, uint32_t dco_freq,
+                                     uint32_t ref_freq, uint32_t pdiv, uint32_t qdiv,
+                                     uint32_t kdiv)
+{
+       switch (kdiv) {
+       case 1:
+               params->kdiv = 1;
+               break;
+       case 2:
+               params->kdiv = 2;
+               break;
+       case 3:
+               params->kdiv = 4;
+               break;
+       default:
+               WARN(1, "Incorrect KDiv\n");
+       }
+
+       switch (pdiv) {
+       case 2:
+               params->pdiv = 1;
+               break;
+       case 3:
+               params->pdiv = 2;
+               break;
+       case 5:
+               params->pdiv = 4;
+               break;
+       case 7:
+               params->pdiv = 8;
+               break;
+       default:
+               WARN(1, "Incorrect PDiv\n");
+       }
+
+       if (kdiv != 2)
+               qdiv = 1;
+
+       params->qdiv_ratio = qdiv;
+       params->qdiv_mode = (qdiv == 1) ? 0 : 1;
+
+       params->dco_integer = div_u64(dco_freq, ref_freq);
+       params->dco_fraction = div_u64((div_u64((uint64_t)dco_freq<<15, (uint64_t)ref_freq) -
+                                       ((uint64_t)params->dco_integer<<15)) * 0x8000, 0x8000);
+}
+
+static bool
+cnl_ddi_calculate_wrpll(int clock /* in Hz */,
+                       struct drm_i915_private *dev_priv,
+                       struct skl_wrpll_params *wrpll_params)
+{
+       uint64_t afe_clock = clock * 5 / KHz(1); /* clocks in kHz */
+       unsigned int dco_min = 7998 * KHz(1);
+       unsigned int dco_max = 10000 * KHz(1);
+       unsigned int dco_mid = (dco_min + dco_max) / 2;
+
+       static const int dividers[] = {  2,  4,  6,  8, 10, 12,  14,  16,
+                                        18, 20, 24, 28, 30, 32,  36,  40,
+                                        42, 44, 48, 50, 52, 54,  56,  60,
+                                        64, 66, 68, 70, 72, 76,  78,  80,
+                                        84, 88, 90, 92, 96, 98, 100, 102,
+                                         3,  5,  7,  9, 15, 21 };
+       unsigned int d, dco;
+       unsigned int dco_centrality = 0;
+       unsigned int best_dco_centrality = 999999;
+       unsigned int best_div = 0;
+       unsigned int best_dco = 0;
+       unsigned int pdiv = 0, qdiv = 0, kdiv = 0;
+
+       for (d = 0; d < ARRAY_SIZE(dividers); d++) {
+               dco = afe_clock * dividers[d];
+
+               if ((dco <= dco_max) && (dco >= dco_min)) {
+                       dco_centrality = abs(dco - dco_mid);
+
+                       if (dco_centrality < best_dco_centrality) {
+                               best_dco_centrality = dco_centrality;
+                               best_div = dividers[d];
+                               best_dco = dco;
+                       }
+               }
+       }
+
+       if (best_div == 0)
+               return false;
+
+       cnl_wrpll_get_multipliers(best_div, &pdiv, &qdiv, &kdiv);
+
+       cnl_wrpll_params_populate(wrpll_params, best_dco,
+                                 dev_priv->cdclk.hw.ref, pdiv, qdiv, kdiv);
+
+       return true;
+}
+
 static bool cnl_ddi_hdmi_pll_dividers(struct intel_crtc *crtc,
                                      struct intel_crtc_state *crtc_state,
                                      int clock)
 {
+       struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
        uint32_t cfgcr0, cfgcr1;
        struct skl_wrpll_params wrpll_params = { 0, };
 
        cfgcr0 = DPLL_CFGCR0_HDMI_MODE;
 
-       /* FIXME: Proper wrpll calculation done in a following patch */
-       return false;
+       if (!cnl_ddi_calculate_wrpll(clock * 1000, dev_priv, &wrpll_params))
+               return false;
 
        cfgcr0 |= DPLL_CFGCR0_DCO_FRACTION(wrpll_params.dco_fraction) |
                wrpll_params.dco_integer;