From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 arch/arm/mach-rpc/include/mach/acornfb.h | 140 +++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 arch/arm/mach-rpc/include/mach/acornfb.h

(limited to 'arch/arm/mach-rpc/include/mach/acornfb.h')

diff --git a/arch/arm/mach-rpc/include/mach/acornfb.h b/arch/arm/mach-rpc/include/mach/acornfb.h
new file mode 100644
index 00000000..395d7628
--- /dev/null
+++ b/arch/arm/mach-rpc/include/mach/acornfb.h
@@ -0,0 +1,140 @@
+/*
+ *  arch/arm/mach-rpc/include/mach/acornfb.h
+ *
+ *  Copyright (C) 1999 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ *  AcornFB architecture specific code
+ */
+
+#define acornfb_bandwidth(var) ((var)->pixclock * 8 / (var)->bits_per_pixel)
+
+static inline int
+acornfb_valid_pixrate(struct fb_var_screeninfo *var)
+{
+	u_long limit;
+
+	if (!var->pixclock)
+		return 0;
+
+	/*
+	 * Limits below are taken from RISC OS bandwidthlimit file
+	 */
+	if (current_par.using_vram) {
+		if (current_par.vram_half_sam == 2048)
+			limit = 6578;
+		else
+			limit = 13157;
+	} else {
+		limit = 26315;
+	}
+
+	return acornfb_bandwidth(var) >= limit;
+}
+
+/*
+ * 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;
+
+	/* 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;
+	}
+
+	/*
+	 * With VRAM, the FIFO can be set to the highest possible setting
+	 * because there are no latency considerations for other memory
+	 * accesses. However, in 64 bit bus mode the FIFO preload value
+	 * must not be set to VIDC20_CTRL_FIFO_28 because this will let
+	 * the FIFO overflow. See VIDC20 manual page 33 (6.0 Setting the
+	 * FIFO preload value).
+	 */
+	if (current_par.using_vram) {
+		if (current_par.vram_half_sam == 2048)
+			vidc->control |= VIDC20_CTRL_FIFO_24;
+		else
+			vidc->control |= VIDC20_CTRL_FIFO_28;
+	} else {
+		unsigned long bandwidth = acornfb_bandwidth(var);
+
+		/* Encode bandwidth as VIDC20 setting */
+		if (bandwidth > 33334)		/* < 30.0MB/s */
+			vidc->control |= VIDC20_CTRL_FIFO_16;
+		else if (bandwidth > 26666)	/* < 37.5MB/s */
+			vidc->control |= VIDC20_CTRL_FIFO_20;
+		else if (bandwidth > 22222)	/* < 45.0MB/s */
+			vidc->control |= VIDC20_CTRL_FIFO_24;
+		else				/* > 45.0MB/s */
+			vidc->control |= VIDC20_CTRL_FIFO_28;
+	}
+
+	/* 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))
-- 
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