DRM: Armada: Add Armada DRM driver

This patch adds support for the pair of LCD controllers on the Marvell
Armada 510 SoCs.  This driver supports:
- multiple contiguous scanout buffers for video and graphics
- shm backed cacheable buffer objects for X pixmaps for Vivante GPU
  acceleration
- dual lcd0 and lcd1 crt operation
- video overlay on each LCD crt via DRM planes
- page flipping of the main scanout buffers
- DRM prime for buffer export/import

This driver is trivial to extend to other Armada SoCs.

Included in this commit is the core driver with no output support; output
support is platform and encoder driver dependent.

Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 86 insertions, 0 deletions

diff --git a/drivers/gpu/drm/armada/armada_510.c b/drivers/gpu/drm/armada/armada_510.c
new file mode 100644
index 000000000000..a016888acd29
--- /dev/null
+++ b/drivers/gpu/drm/armada/armada_510.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2012 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.
+ *
+ * Armada 510 (aka Dove) variant support
+ */
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <drm/drmP.h>
+#include <drm/drm_crtc_helper.h>
+#include "armada_crtc.h"
+#include "armada_drm.h"
+#include "armada_hw.h"
+
+static int armada510_init(struct armada_private *priv, struct device *dev)
+{
+	priv->extclk[0] = devm_clk_get(dev, "ext_ref_clk_1");
+
+	if (IS_ERR(priv->extclk[0]) && PTR_ERR(priv->extclk[0]) == -ENOENT)
+		priv->extclk[0] = ERR_PTR(-EPROBE_DEFER);
+
+	return PTR_RET(priv->extclk[0]);
+}
+
+static int armada510_crtc_init(struct armada_crtc *dcrtc)
+{
+	/* Lower the watermark so to eliminate jitter at higher bandwidths */
+	armada_updatel(0x20, (1 << 11) | 0xff, dcrtc->base + LCD_CFG_RDREG4F);
+	return 0;
+}
+
+/*
+ * Armada510 specific SCLK register selection.
+ * This gets called with sclk = NULL to test whether the mode is
+ * supportable, and again with sclk != NULL to set the clocks up for
+ * that.  The former can return an error, but the latter is expected
+ * not to.
+ *
+ * We currently are pretty rudimentary here, always selecting
+ * EXT_REF_CLK_1 for LCD0 and erroring LCD1.  This needs improvement!
+ */
+static int armada510_crtc_compute_clock(struct armada_crtc *dcrtc,
+	const struct drm_display_mode *mode, uint32_t *sclk)
+{
+	struct armada_private *priv = dcrtc->crtc.dev->dev_private;
+	struct clk *clk = priv->extclk[0];
+	int ret;
+
+	if (dcrtc->num == 1)
+		return -EINVAL;
+
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	if (dcrtc->clk != clk) {
+		ret = clk_prepare_enable(clk);
+		if (ret)
+			return ret;
+		dcrtc->clk = clk;
+	}
+
+	if (sclk) {
+		uint32_t rate, ref, div;
+
+		rate = mode->clock * 1000;
+		ref = clk_round_rate(clk, rate);
+		div = DIV_ROUND_UP(ref, rate);
+		if (div < 1)
+			div = 1;
+
+		clk_set_rate(clk, ref);
+		*sclk = div | SCLK_510_EXTCLK1;
+	}
+
+	return 0;
+}
+
+const struct armada_variant armada510_ops = {
+	.has_spu_adv_reg = true,
+	.init = armada510_init,
+	.crtc_init = armada510_crtc_init,
+	.crtc_compute_clock = armada510_crtc_compute_clock,
+};