4 files changed, 163 insertions, 0 deletions

diff --git a/drivers/gpu/drm/meson/Makefile b/drivers/gpu/drm/meson/Makefile
index c389e2399133..fb7f5440fe57 100644
--- a/drivers/gpu/drm/meson/Makefile
+++ b/drivers/gpu/drm/meson/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 meson-drm-y := meson_drv.o meson_plane.o meson_crtc.o meson_venc_cvbs.o
 meson-drm-y += meson_viu.o meson_vpp.o meson_venc.o meson_vclk.o meson_overlay.o
+meson-drm-y += meson_rdma.o
 
 obj-$(CONFIG_DRM_MESON) += meson-drm.o
 obj-$(CONFIG_DRM_MESON_DW_HDMI) += meson_dw_hdmi.o
diff --git a/drivers/gpu/drm/meson/meson_drv.h b/drivers/gpu/drm/meson/meson_drv.h
index 3287282450a9..ea39be913c0f 100644
--- a/drivers/gpu/drm/meson/meson_drv.h
+++ b/drivers/gpu/drm/meson/meson_drv.h
@@ -123,6 +123,12 @@ struct meson_drm {
 		bool venc_repeat;
 		bool hdmi_use_enci;
 	} venc;
+
+	struct {
+		dma_addr_t addr_phys;
+		uint32_t *addr;
+		unsigned int offset;
+	} rdma;
 };
 
 static inline int meson_vpu_is_compatible(struct meson_drm *priv,
diff --git a/drivers/gpu/drm/meson/meson_rdma.c b/drivers/gpu/drm/meson/meson_rdma.c
new file mode 100644
index 000000000000..25b34b1e72a7
--- /dev/null
+++ b/drivers/gpu/drm/meson/meson_rdma.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/dma-mapping.h>
+
+#include "meson_drv.h"
+#include "meson_registers.h"
+#include "meson_rdma.h"
+
+/*
+ * The VPU embeds a "Register DMA" that can write a sequence of registers
+ * on the VPU AHB bus, either manually or triggered by an internal IRQ
+ * event like VSYNC or a line input counter.
+ * The initial implementation handles a single channel (over 8), triggered
+ * by the VSYNC irq and does not handle the RDMA irq.
+ */
+
+#define RDMA_DESC_SIZE	(sizeof(uint32_t) * 2)
+
+int meson_rdma_init(struct meson_drm *priv)
+{
+	if (!priv->rdma.addr) {
+		/* Allocate a PAGE buffer */
+		priv->rdma.addr =
+			dma_alloc_coherent(priv->dev, SZ_4K,
+					   &priv->rdma.addr_phys,
+					   GFP_KERNEL);
+		if (!priv->rdma.addr)
+			return -ENOMEM;
+	}
+
+	priv->rdma.offset = 0;
+
+	writel_relaxed(RDMA_CTRL_SW_RESET,
+		       priv->io_base + _REG(RDMA_CTRL));
+	writel_relaxed(RDMA_DEFAULT_CONFIG |
+		       FIELD_PREP(RDMA_CTRL_AHB_WR_BURST, 3) |
+		       FIELD_PREP(RDMA_CTRL_AHB_RD_BURST, 0),
+		       priv->io_base + _REG(RDMA_CTRL));
+
+	return 0;
+}
+
+void meson_rdma_free(struct meson_drm *priv)
+{
+	if (!priv->rdma.addr && !priv->rdma.addr_phys)
+		return;
+
+	meson_rdma_stop(priv);
+
+	dma_free_coherent(priv->dev, SZ_4K,
+			  priv->rdma.addr, priv->rdma.addr_phys);
+
+	priv->rdma.addr = NULL;
+	priv->rdma.addr_phys = (dma_addr_t)NULL;
+}
+
+void meson_rdma_setup(struct meson_drm *priv)
+{
+	/* Channel 1: Write Flag, No Address Increment */
+	writel_bits_relaxed(RDMA_ACCESS_RW_FLAG_CHAN1 |
+			    RDMA_ACCESS_ADDR_INC_CHAN1,
+			    RDMA_ACCESS_RW_FLAG_CHAN1,
+			    priv->io_base + _REG(RDMA_ACCESS_AUTO));
+}
+
+void meson_rdma_stop(struct meson_drm *priv)
+{
+	writel_bits_relaxed(RDMA_IRQ_CLEAR_CHAN1,
+			    RDMA_IRQ_CLEAR_CHAN1,
+			    priv->io_base + _REG(RDMA_CTRL));
+
+	/* Stop Channel 1 */
+	writel_bits_relaxed(RDMA_ACCESS_TRIGGER_CHAN1,
+			    FIELD_PREP(RDMA_ACCESS_ADDR_INC_CHAN1,
+				       RDMA_ACCESS_TRIGGER_STOP),
+			    priv->io_base + _REG(RDMA_ACCESS_AUTO));
+}
+
+void meson_rdma_reset(struct meson_drm *priv)
+{
+	meson_rdma_stop(priv);
+
+	priv->rdma.offset = 0;
+}
+
+static void meson_rdma_writel(struct meson_drm *priv, uint32_t val,
+			      uint32_t reg)
+{
+	if (priv->rdma.offset >= (SZ_4K / RDMA_DESC_SIZE)) {
+		dev_warn_once(priv->dev, "%s: overflow\n", __func__);
+		return;
+	}
+
+	priv->rdma.addr[priv->rdma.offset++] = reg;
+	priv->rdma.addr[priv->rdma.offset++] = val;
+}
+
+/*
+ * This will add the register to the RDMA buffer and write it to the
+ * hardware at the same time.
+ * When meson_rdma_flush is called, the RDMA will replay the register
+ * writes in order.
+ */
+void meson_rdma_writel_sync(struct meson_drm *priv, uint32_t val, uint32_t reg)
+{
+	meson_rdma_writel(priv, val, reg);
+
+	writel_relaxed(val, priv->io_base + _REG(reg));
+}
+
+void meson_rdma_flush(struct meson_drm *priv)
+{
+	meson_rdma_stop(priv);
+
+	/* Start of Channel 1 register writes buffer */
+	writel(priv->rdma.addr_phys,
+	       priv->io_base + _REG(RDMA_AHB_START_ADDR_1));
+
+	/* Last byte on Channel 1 register writes buffer */
+	writel(priv->rdma.addr_phys + (priv->rdma.offset * RDMA_DESC_SIZE) - 1,
+	       priv->io_base + _REG(RDMA_AHB_END_ADDR_1));
+
+	/* Trigger Channel 1 on VSYNC event */
+	writel_bits_relaxed(RDMA_ACCESS_TRIGGER_CHAN1,
+			    FIELD_PREP(RDMA_ACCESS_TRIGGER_CHAN1,
+				       RDMA_ACCESS_TRIGGER_VSYNC),
+			    priv->io_base + _REG(RDMA_ACCESS_AUTO));
+
+	priv->rdma.offset = 0;
+}
diff --git a/drivers/gpu/drm/meson/meson_rdma.h b/drivers/gpu/drm/meson/meson_rdma.h
new file mode 100644
index 000000000000..3870bff7b47f
--- /dev/null
+++ b/drivers/gpu/drm/meson/meson_rdma.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2019 BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#ifndef __MESON_RDMA_H
+#define __MESON_RDMA_H
+
+#include "meson_drv.h"
+
+int meson_rdma_init(struct meson_drm *priv);
+void meson_rdma_free(struct meson_drm *priv);
+void meson_rdma_setup(struct meson_drm *priv);
+void meson_rdma_reset(struct meson_drm *priv);
+void meson_rdma_stop(struct meson_drm *priv);
+
+void meson_rdma_writel_sync(struct meson_drm *priv, uint32_t val, uint32_t reg);
+void meson_rdma_flush(struct meson_drm *priv);
+
+#endif /* __MESON_RDMA_H */