patch-2.3.23 linux/include/asm-arm/arch-rpc/acornfb.h

• Lines: 100
• Date: Wed Oct 20 16:29:08 1999
• Orig file: v2.3.22/linux/include/asm-arm/arch-rpc/acornfb.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.22/linux/include/asm-arm/arch-rpc/acornfb.h linux/include/asm-arm/arch-rpc/acornfb.h
@@ -0,0 +1,99 @@
+/*
+ * linux/include/asm-arm/arch-rpc/acornfb.h
+ *
+ * (C) 1999 Russell King
+ *
+ * AcornFB architecture specific code
+ */
+
+#define acornfb_valid_pixrate(rate) (1)
+
+/*
+ * Try to find the best PLL parameters for the pixel clock.
+ * This algorithm seems to give best predictable results,
+ * and produces the same values as detailed in the VIDC20
+ * data sheet.
+ */
+static inline u_int
+acornfb_vidc20_find_pll(u_int pixclk)
+{
+	u_int r, best_r = 2, best_v = 2;
+	int best_d = 0x7fffffff;
+
+	for (r = 2; r <= 32; r++) {
+		u_int rr, v, p;
+		int d;
+
+		rr = 41667 * r;
+
+		v = (rr + pixclk / 2) / pixclk;
+
+		if (v > 32 || v < 2)
+			continue;
+
+		p = (rr + v / 2) / v;
+
+		d = pixclk - p;
+
+		if (d < 0)
+			d = -d;
+
+		if (d < best_d) {
+			best_d = d;
+			best_v = v - 1;
+			best_r = r - 1;
+		}
+
+		if (d == 0)
+			break;
+	}
+
+	return best_v << 8 | best_r;
+}
+
+static inline void
+acornfb_vidc20_find_rates(struct vidc_timing *vidc,
+			  struct fb_var_screeninfo *var)
+{
+	u_int div, bandwidth;
+
+	/* Select pixel-clock divisor to keep PLL in range */
+	div = var->pixclock / 9090; /*9921*/
+
+	/* Limit divisor */
+	if (div == 0)
+		div = 1;
+	if (div > 8)
+		div = 8;
+
+	/* Encode divisor to VIDC20 setting */
+	switch (div) {
+	case 1:	vidc->control |= VIDC20_CTRL_PIX_CK;  break;
+	case 2:	vidc->control |= VIDC20_CTRL_PIX_CK2; break;
+	case 3:	vidc->control |= VIDC20_CTRL_PIX_CK3; break;
+	case 4:	vidc->control |= VIDC20_CTRL_PIX_CK4; break;
+	case 5:	vidc->control |= VIDC20_CTRL_PIX_CK5; break;
+	case 6:	vidc->control |= VIDC20_CTRL_PIX_CK6; break;
+	case 7:	vidc->control |= VIDC20_CTRL_PIX_CK7; break;
+	case 8: vidc->control |= VIDC20_CTRL_PIX_CK8; break;
+	}
+
+	/* Calculate bandwidth */
+	bandwidth = var->pixclock * 8 / var->bits_per_pixel;
+
+	/* Encode bandwidth as VIDC20 setting */
+	if (bandwidth > 33334)
+		vidc->control |= VIDC20_CTRL_FIFO_16;	/* < 30.0MB/s */
+	else if (bandwidth > 26666)
+		vidc->control |= VIDC20_CTRL_FIFO_20;	/* < 37.5MB/s */
+	else if (bandwidth > 22222)
+		vidc->control |= VIDC20_CTRL_FIFO_24;	/* < 45.0MB/s */
+	else
+		vidc->control |= VIDC20_CTRL_FIFO_28;	/* > 45.0MB/s */
+
+	/* Find the PLL values */
+	vidc->pll_ctl  = acornfb_vidc20_find_pll(var->pixclock / div);
+}
+
+#define acornfb_default_control()	(VIDC20_CTRL_PIX_VCLK)
+#define acornfb_default_econtrol()	(VIDC20_ECTL_DAC | VIDC20_ECTL_REG(3))