drm/nv50: support fractional feedback divider on newer chips

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nv50_calc.c b/drivers/gpu/drm/nouveau/nv50_calc.c
new file mode 100644
index 00000000000..2cdc2bfe717
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/nv50_calc.c
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2010 Red Hat Inc.
+ *
+ * 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.
+ *
+ * Authors: Ben Skeggs
+ */
+
+#include "drmP.h"
+#include "drm_fixed.h"
+#include "nouveau_drv.h"
+#include "nouveau_hw.h"
+
+int
+nv50_calc_pll(struct drm_device *dev, struct pll_lims *pll, int clk,
+	      int *N1, int *M1, int *N2, int *M2, int *P)
+{
+	struct nouveau_pll_vals pll_vals;
+	int ret;
+
+	ret = nouveau_calc_pll_mnp(dev, pll, clk, &pll_vals);
+	if (ret <= 0)
+		return ret;
+
+	*N1 = pll_vals.N1;
+	*M1 = pll_vals.M1;
+	*N2 = pll_vals.N2;
+	*M2 = pll_vals.M2;
+	*P = pll_vals.log2P;
+	return ret;
+}
+
+int
+nv50_calc_pll2(struct drm_device *dev, struct pll_lims *pll, int clk,
+	       int *N, int *fN, int *M, int *P)
+{
+	fixed20_12 fb_div, a, b;
+
+	*P = pll->vco1.maxfreq / clk;
+	if (*P > pll->max_p)
+		*P = pll->max_p;
+	if (*P < pll->min_p)
+		*P = pll->min_p;
+
+	/* *M = ceil(refclk / pll->vco.max_inputfreq); */
+	a.full = dfixed_const(pll->refclk);
+	b.full = dfixed_const(pll->vco1.max_inputfreq);
+	a.full = dfixed_div(a, b);
+	a.full = dfixed_ceil(a);
+	*M = dfixed_trunc(a);
+
+	/* fb_div = (vco * *M) / refclk; */
+	fb_div.full = dfixed_const(clk * *P);
+	fb_div.full = dfixed_mul(fb_div, a);
+	a.full = dfixed_const(pll->refclk);
+	fb_div.full = dfixed_div(fb_div, a);
+
+	/* *N = floor(fb_div); */
+	a.full = dfixed_floor(fb_div);
+	*N = dfixed_trunc(fb_div);
+
+	/* *fN = (fmod(fb_div, 1.0) * 8192) - 4096; */
+	b.full = dfixed_const(8192);
+	a.full = dfixed_mul(a, b);
+	fb_div.full = dfixed_mul(fb_div, b);
+	fb_div.full = fb_div.full - a.full;
+	*fN = dfixed_trunc(fb_div) - 4096;
+	*fN &= 0xffff;
+
+	return clk;
+}