The Allwinner A31 has a 16 channels DMA controller that it shares with the
newer A23. Although sharing some similarities with the DMA controller of the
older Allwinner SoCs, it's significantly different, I don't expect it to be
possible to share the driver for these two.

The A31 Controller is able to memory-to-memory or memory-to-device transfers on
the 16 channels in parallel.

Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
---
 .../devicetree/bindings/dma/sun6i-dma.txt          |  45 +
 drivers/dma/Kconfig                                |   8 +
 drivers/dma/Makefile                               |   1 +
 drivers/dma/sun6i-dma.c                            | 986 +++++++++++++++++++++
 4 files changed, 1040 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/sun6i-dma.txt
 create mode 100644 drivers/dma/sun6i-dma.c

diff --git a/Documentation/devicetree/bindings/dma/sun6i-dma.txt 
b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
new file mode 100644
index 000000000000..5d7c86d52665
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
@@ -0,0 +1,45 @@
+Allwinner A31 DMA Controller
+
+This driver follows the generic DMA bindings defined in dma.txt.
+
+Required properties:
+
+- compatible:  Must be "allwinner,sun6i-a31-dma"
+- reg:         Should contain the registers base address and length
+- interrupts:  Should contain a reference to the interrupt used by this device
+- clocks:      Should contain a reference to the parent AHB clock
+- resets:      Should contain a reference to the reset controller asserting
+               this device in reset
+- #dma-cells : Should be 1, a single cell holding a line request number
+
+Example:
+       dma: dma-controller@01c02000 {
+               compatible = "allwinner,sun6i-a31-dma";
+               reg = <0x01c02000 0x1000>;
+               interrupts = <0 50 4>;
+               clocks = <&ahb1_gates 6>;
+               resets = <&ahb1_rst 6>;
+               #dma-cells = <1>;
+       };
+
+Clients:
+
+DMA clients connected to the A31 DMA controller must use the format
+described in the dma.txt file, using a two-cell specifier for each
+channel: a phandle plus one integer cells.
+The two cells in order are:
+
+1. A phandle pointing to the DMA controller.
+2. The port ID as specified in the datasheet
+
+Example:
+spi2: spi@01c6a000 {
+       compatible = "allwinner,sun6i-a31-spi";
+       reg = <0x01c6a000 0x1000>;
+       interrupts = <0 67 4>;
+       clocks = <&ahb1_gates 22>, <&spi2_clk>;
+       clock-names = "ahb", "mod";
+       dmas = <&dma 25>, <&dma 25>;
+       dma-names = "rx", "tx";
+       resets = <&ahb1_rst 22>;
+};
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 605b016bcea4..7923697eaa2e 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -351,6 +351,14 @@ config MOXART_DMA
        help
          Enable support for the MOXA ART SoC DMA controller.
 
+config DMA_SUN6I
+       tristate "Allwinner A31 SoCs DMA support"
+       depends on ARCH_SUNXI
+       select DMA_ENGINE
+       select DMA_VIRTUAL_CHANNELS
+       help
+         Support for the DMA engine for Allwinner A31 SoCs.
+
 config DMA_ENGINE
        bool
 
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index a029d0f4a1be..18cdbad1927c 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -44,3 +44,4 @@ obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
 obj-$(CONFIG_TI_CPPI41) += cppi41.o
 obj-$(CONFIG_K3_DMA) += k3dma.o
 obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
+obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
new file mode 100644
index 000000000000..a11040633b30
--- /dev/null
+++ b/drivers/dma/sun6i-dma.c
@@ -0,0 +1,986 @@
+/*
+ * Copyright (C) 2013-2014 Allwinner Tech Co., Ltd
+ * Author: Sugar <sh...@allwinnertech.com>
+ *
+ * Copyright (C) 2014 Maxime Ripard
+ * Maxime Ripard <maxime.rip...@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "virt-dma.h"
+
+/*
+ * There's 16 physical channels that can work in parallel.
+ *
+ * However we have 30 different endpoints for our requests.
+ *
+ * Since the channels are able to handle only an unidirectional
+ * transfer, we need to allocate more virtual channels so that
+ * everyone can grab one channel.
+ *
+ * Some devices can't work in both direction (mostly because it
+ * wouldn't make sense), so we have a bit fewer virtual channels than
+ * 2 channels per endpoints.
+ */
+
+#define NR_MAX_CHANNELS                16
+#define NR_MAX_REQUESTS                30
+#define NR_MAX_VCHANS          53
+
+/*
+ * Common registers
+ */
+#define DMA_IRQ_EN(x)          ((x) * 0x04)
+#define DMA_IRQ_HALF                   BIT(0)
+#define DMA_IRQ_PKG                    BIT(1)
+#define DMA_IRQ_QUEUE                  BIT(2)
+
+#define DMA_IRQ_CHAN_NR                        8
+#define DMA_IRQ_CHAN_WIDTH             4
+
+
+#define DMA_IRQ_STAT(x)                ((x) * 0x04 + 0x10)
+
+#define DMA_STAT               0x30
+
+/*
+ * Channels specific registers
+ */
+#define DMA_CHAN_ENABLE                0x00
+#define DMA_CHAN_ENABLE_START          BIT(0)
+#define DMA_CHAN_ENABLE_STOP           0
+
+#define DMA_CHAN_PAUSE         0x04
+#define DMA_CHAN_PAUSE_PAUSE           BIT(1)
+#define DMA_CHAN_PAUSE_RESUME          0
+
+#define DMA_CHAN_LLI_ADDR      0x08
+
+#define DMA_CHAN_CUR_CFG       0x0c
+#define DMA_CHAN_CFG_SRC_DRQ(x)                ((x) & 0x1f)
+#define DMA_CHAN_CFG_SRC_IO_MODE       BIT(5)
+#define DMA_CHAN_CFG_SRC_LINEAR_MODE   (0 << 5)
+#define DMA_CHAN_CFG_SRC_BURST(x)      (((x) & 0x3) << 7)
+#define DMA_CHAN_CFG_SRC_WIDTH(x)      (((x) & 0x3) << 9)
+
+#define DMA_CHAN_CFG_DST_DRQ(x)                (DMA_CHAN_CFG_SRC_DRQ(x) << 16)
+#define DMA_CHAN_CFG_DST_IO_MODE       (DMA_CHAN_CFG_SRC_IO_MODE << 16)
+#define DMA_CHAN_CFG_DST_LINEAR_MODE   (DMA_CHAN_CFG_SRC_LINEAR_MODE << 16)
+#define DMA_CHAN_CFG_DST_BURST(x)      (DMA_CHAN_CFG_SRC_BURST(x) << 16)
+#define DMA_CHAN_CFG_DST_WIDTH(x)      (DMA_CHAN_CFG_SRC_WIDTH(x) << 16)
+
+#define DMA_CHAN_CUR_SRC       0x10
+
+#define DMA_CHAN_CUR_DST       0x14
+
+#define DMA_CHAN_CUR_CNT       0x18
+
+#define DMA_CHAN_CUR_PARA      0x1c
+
+
+/*
+ * Various hardware related defines
+ */
+#define LLI_LAST_ITEM  0xfffff800
+#define NORMAL_WAIT    8
+#define DRQ_SDRAM      1
+
+/*
+ * Hardware representation of the LLI
+ *
+ * The hardware will be fed the physical address of this structure,
+ * and read its content in order to start the transfer.
+ */
+struct sun6i_dma_lli {
+       u32                     cfg;
+       u32                     src;
+       u32                     dst;
+       u32                     len;
+       u32                     para;
+       u32                     p_lli_next;
+       struct sun6i_dma_lli    *v_lli_next;
+} __packed;
+
+
+struct sun6i_desc {
+       struct virt_dma_desc    vd;
+       dma_addr_t              p_lli;
+       struct sun6i_dma_lli    *v_lli;
+};
+
+struct sun6i_pchan {
+       u32                     idx;
+       void __iomem            *base;
+       struct sun6i_vchan      *vchan;
+       struct sun6i_desc       *desc;
+       struct sun6i_desc       *done;
+};
+
+struct sun6i_vchan {
+       struct virt_dma_chan    vc;
+       struct list_head        node;
+       struct dma_slave_config cfg;
+       struct sun6i_pchan      *phy;
+       u8                      port;
+};
+
+struct sun6i_dma_dev {
+       struct dma_device       slave;
+       void __iomem            *base;
+       struct clk              *clk;
+       struct reset_control    *rstc;
+       spinlock_t              lock;
+       struct tasklet_struct   task;
+       struct list_head        pending;
+       struct dma_pool         *pool;
+       struct sun6i_pchan      *pchans;
+       struct sun6i_vchan      *vchans;
+};
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+       return &chan->dev->device;
+}
+
+static inline struct sun6i_dma_dev *to_sun6i_dma_dev(struct dma_device *d)
+{
+       return container_of(d, struct sun6i_dma_dev, slave);
+}
+
+static inline struct sun6i_vchan *to_sun6i_vchan(struct dma_chan *chan)
+{
+       return container_of(chan, struct sun6i_vchan, vc.chan);
+}
+
+static inline struct sun6i_desc *
+to_sun6i_desc(struct dma_async_tx_descriptor *tx)
+{
+       return container_of(tx, struct sun6i_desc, vd.tx);
+}
+
+static inline void sun6i_dma_dump_com_regs(struct sun6i_dma_dev *sdev)
+{
+       dev_dbg(sdev->slave.dev, "Common register:\n"
+               "\tmask0(%04x): 0x%08x\n"
+               "\tmask1(%04x): 0x%08x\n"
+               "\tpend0(%04x): 0x%08x\n"
+               "\tpend1(%04x): 0x%08x\n"
+               "\tstats(%04x): 0x%08x\n",
+               DMA_IRQ_EN(0), readl(sdev->base + DMA_IRQ_EN(0)),
+               DMA_IRQ_EN(1), readl(sdev->base + DMA_IRQ_EN(1)),
+               DMA_IRQ_STAT(0), readl(sdev->base + DMA_IRQ_STAT(0)),
+               DMA_IRQ_STAT(1), readl(sdev->base + DMA_IRQ_STAT(1)),
+               DMA_STAT, readl(sdev->base + DMA_STAT));
+}
+
+static inline void sun6i_dma_dump_chan_regs(struct sun6i_dma_dev *sdev,
+                                           struct sun6i_pchan *pchan)
+{
+       phys_addr_t reg = __virt_to_phys((unsigned long)pchan->base);
+
+       dev_dbg(sdev->slave.dev, "Chan %d reg: %pa\n"
+               "\t___en(%04x): \t0x%08x\n"
+               "\tpause(%04x): \t0x%08x\n"
+               "\tstart(%04x): \t0x%08x\n"
+               "\t__cfg(%04x): \t0x%08x\n"
+               "\t__src(%04x): \t0x%08x\n"
+               "\t__dst(%04x): \t0x%08x\n"
+               "\tcount(%04x): \t0x%08x\n"
+               "\t_para(%04x): \t0x%08x\n\n",
+               pchan->idx, &reg,
+               DMA_CHAN_ENABLE,
+               readl(pchan->base + DMA_CHAN_ENABLE),
+               DMA_CHAN_PAUSE,
+               readl(pchan->base + DMA_CHAN_PAUSE),
+               DMA_CHAN_LLI_ADDR,
+               readl(pchan->base + DMA_CHAN_LLI_ADDR),
+               DMA_CHAN_CUR_CFG,
+               readl(pchan->base + DMA_CHAN_CUR_CFG),
+               DMA_CHAN_CUR_SRC,
+               readl(pchan->base + DMA_CHAN_CUR_SRC),
+               DMA_CHAN_CUR_DST,
+               readl(pchan->base + DMA_CHAN_CUR_DST),
+               DMA_CHAN_CUR_CNT,
+               readl(pchan->base + DMA_CHAN_CUR_CNT),
+               DMA_CHAN_CUR_PARA,
+               readl(pchan->base + DMA_CHAN_CUR_PARA));
+}
+
+static inline u8 convert_burst(u8 maxburst)
+{
+       if (maxburst == 1 || maxburst > 16)
+               return 0;
+
+       return fls(maxburst) - 1;
+}
+
+static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
+{
+       switch (addr_width) {
+       case DMA_SLAVE_BUSWIDTH_2_BYTES:
+               return 1;
+       case DMA_SLAVE_BUSWIDTH_4_BYTES:
+               return 2;
+       default:
+               return 0;
+       }
+}
+
+static void *sun6i_dma_lli_add(struct sun6i_dma_lli *prev,
+                              struct sun6i_dma_lli *next,
+                              dma_addr_t next_phy,
+                              struct sun6i_desc *txd)
+{
+       if ((!prev && !txd) || !next)
+               return NULL;
+
+       if (!prev) {
+               txd->p_lli = next_phy;
+               txd->v_lli = next;
+       } else {
+               prev->p_lli_next = next_phy;
+               prev->v_lli_next = next;
+       }
+
+       next->p_lli_next = LLI_LAST_ITEM;
+       next->v_lli_next = NULL;
+
+       return next;
+}
+
+static inline void sun6i_dma_cfg_lli(struct sun6i_dma_lli *lli,
+                                    dma_addr_t src,
+                                    dma_addr_t dst, u32 len,
+                                    struct dma_slave_config *config)
+{
+       u32 src_width, dst_width, src_burst, dst_burst;
+
+       if (!config)
+               return;
+
+       src_burst = convert_burst(config->src_maxburst);
+       dst_burst = convert_burst(config->dst_maxburst);
+
+       src_width = convert_buswidth(config->src_addr_width);
+       dst_width = convert_buswidth(config->dst_addr_width);
+
+       lli->cfg = DMA_CHAN_CFG_SRC_BURST(src_burst) |
+               DMA_CHAN_CFG_SRC_WIDTH(src_width) |
+               DMA_CHAN_CFG_DST_BURST(dst_burst) |
+               DMA_CHAN_CFG_DST_WIDTH(dst_width);
+
+       lli->src = src;
+       lli->dst = dst;
+       lli->len = len;
+       lli->para = NORMAL_WAIT;
+
+}
+
+static inline void sun6i_dma_dump_lli(struct sun6i_vchan *vchan,
+                                     struct sun6i_dma_lli *lli)
+{
+       phys_addr_t p_lli = __virt_to_phys((unsigned long)lli);
+
+       dev_dbg(chan2dev(&vchan->vc.chan),
+               "\n\tdesc:   p - %pa v - 0x%08x\n"
+               "\t\tc - 0x%08x s - 0x%08x d - 0x%08x\n"
+               "\t\tl - 0x%08x p - 0x%08x n - 0x%08x\n",
+               &p_lli, (u32)lli,
+               lli->cfg, lli->src, lli->dst,
+               lli->len, lli->para, lli->p_lli_next);
+}
+
+static void sun6i_dma_free_desc(struct virt_dma_desc *vd)
+{
+       struct sun6i_desc *txd = to_sun6i_desc(&vd->tx);
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device);
+       struct sun6i_dma_lli *v_lli, *v_next;
+       dma_addr_t p_lli, p_next;
+
+       if (unlikely(!txd))
+               return;
+
+       p_lli = txd->p_lli;
+       v_lli = txd->v_lli;
+
+       while (v_lli) {
+               v_next = v_lli->v_lli_next;
+               p_next = v_lli->p_lli_next;
+
+               dma_pool_free(sdev->pool, v_lli, p_lli);
+
+               v_lli = v_next;
+               p_lli = p_next;
+       }
+
+       kfree(txd);
+}
+
+static int sun6i_dma_terminate_all(struct sun6i_vchan *vchan)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
+       struct sun6i_pchan *pchan = vchan->phy;
+       unsigned long flags;
+       LIST_HEAD(head);
+
+       spin_lock(&sdev->lock);
+       list_del_init(&vchan->node);
+       spin_unlock(&sdev->lock);
+
+       spin_lock_irqsave(&vchan->vc.lock, flags);
+
+       vchan_get_all_descriptors(&vchan->vc, &head);
+
+       if (pchan) {
+               writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
+               writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);
+
+               vchan->phy = NULL;
+               pchan->vchan = NULL;
+               pchan->desc = NULL;
+               pchan->done = NULL;
+       }
+
+       spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+       vchan_dma_desc_free_list(&vchan->vc, &head);
+
+       return 0;
+}
+
+static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
+       struct virt_dma_desc *desc = vchan_next_desc(&vchan->vc);
+       struct sun6i_pchan *pchan = vchan->phy;
+       u32 irq_val, irq_reg, irq_offset;
+
+       if (!pchan)
+               return -EAGAIN;
+
+       if (!desc) {
+               pchan->desc = NULL;
+               pchan->done = NULL;
+               return -EAGAIN;
+       }
+
+       list_del(&desc->node);
+
+       pchan->desc = to_sun6i_desc(&desc->tx);
+       pchan->done = NULL;
+
+       sun6i_dma_dump_lli(vchan, pchan->desc->v_lli);
+
+       irq_reg = pchan->idx / DMA_IRQ_CHAN_NR;
+       irq_offset = pchan->idx % DMA_IRQ_CHAN_NR;
+
+       irq_val = readl(sdev->base + DMA_IRQ_EN(irq_offset));
+       irq_val |= DMA_IRQ_QUEUE << (irq_offset * DMA_IRQ_CHAN_WIDTH);
+       writel(irq_val, sdev->base + DMA_IRQ_EN(irq_offset));
+
+       writel(pchan->desc->p_lli, pchan->base + DMA_CHAN_LLI_ADDR);
+       writel(DMA_CHAN_ENABLE_START, pchan->base + DMA_CHAN_ENABLE);
+
+       sun6i_dma_dump_com_regs(sdev);
+       sun6i_dma_dump_chan_regs(sdev, pchan);
+
+       return 0;
+}
+
+static void sun6i_dma_tasklet(unsigned long data)
+{
+       struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)data;
+       struct sun6i_vchan *vchan;
+       struct sun6i_pchan *pchan;
+       unsigned int pchan_alloc = 0;
+       unsigned int pchan_idx;
+
+       list_for_each_entry(vchan, &sdev->slave.channels, vc.chan.device_node) {
+               spin_lock_irq(&vchan->vc.lock);
+
+               pchan = vchan->phy;
+
+               if (pchan && pchan->done) {
+                       if (sun6i_dma_start_desc(vchan)) {
+                               /*
+                                * No current txd associated with this channel
+                                */
+                               dev_dbg(sdev->slave.dev, "pchan %u: free\n",
+                                       pchan->idx);
+
+                               /* Mark this channel free */
+                               vchan->phy = NULL;
+                               pchan->vchan = NULL;
+                       }
+               }
+               spin_unlock_irq(&vchan->vc.lock);
+       }
+
+       spin_lock_irq(&sdev->lock);
+       for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
+               pchan = &sdev->pchans[pchan_idx];
+
+               if (pchan->vchan == NULL && !list_empty(&sdev->pending)) {
+                       vchan = list_first_entry(&sdev->pending,
+                                                struct sun6i_vchan, node);
+
+                       /* Remove from pending channels */
+                       list_del_init(&vchan->node);
+                       pchan_alloc |= BIT(pchan_idx);
+
+                       /* Mark this channel allocated */
+                       pchan->vchan = vchan;
+                       vchan->phy = pchan;
+                       dev_dbg(sdev->slave.dev, "pchan %u: alloc vchan %p\n",
+                               pchan->idx, &vchan->vc);
+               }
+       }
+       spin_unlock_irq(&sdev->lock);
+
+       for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
+               if (pchan_alloc & BIT(pchan_idx)) {
+                       pchan = sdev->pchans + pchan_idx;
+                       vchan = pchan->vchan;
+                       if (vchan) {
+                               spin_lock_irq(&vchan->vc.lock);
+                               sun6i_dma_start_desc(vchan);
+                               spin_unlock_irq(&vchan->vc.lock);
+                       }
+               }
+       }
+}
+
+static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
+{
+       struct sun6i_dma_dev *sdev = dev_id;
+       struct sun6i_vchan *vchan;
+       struct sun6i_pchan *pchan;
+       int i, j, ret = IRQ_NONE;
+       u32 status;
+
+       for (i = 0; i < 2; i++) {
+               status = readl(sdev->base + DMA_IRQ_STAT(i));
+               if (!status)
+                       continue;
+
+               dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
+                       i ? "high" : "low", status);
+
+               writel(status, sdev->base + DMA_IRQ_STAT(i));
+
+               for (j = 0; (j < 8) && status; j++) {
+                       if (status & DMA_IRQ_QUEUE) {
+                               pchan = sdev->pchans + j;
+                               vchan = pchan->vchan;
+
+                               if (vchan) {
+                                       unsigned long flags;
+
+                                       spin_lock_irqsave(&vchan->vc.lock,
+                                                         flags);
+                                       vchan_cookie_complete(&pchan->desc->vd);
+                                       pchan->done = pchan->desc;
+                                       spin_unlock_irqrestore(&vchan->vc.lock,
+                                                              flags);
+                               }
+                       }
+
+                       status = status >> 4;
+               }
+
+               tasklet_schedule(&sdev->task);
+               ret = IRQ_HANDLED;
+       }
+
+       return ret;
+}
+
+static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_memcpy(
+               struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+               size_t len, unsigned long flags)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       struct dma_slave_config *sconfig = &vchan->cfg;
+       struct sun6i_dma_lli *v_lli;
+       struct sun6i_desc *txd;
+       dma_addr_t p_lli;
+
+       dev_dbg(chan2dev(chan),
+               "%s; chan: %d, dest: %pad, src: %pad, len: %zu. flags: 
0x%08lx\n",
+               __func__, vchan->vc.chan.chan_id, &dest, &src, len, flags);
+
+       if (!len)
+               return NULL;
+
+       txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+       if (!txd)
+               return NULL;
+
+       v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
+       if (!v_lli) {
+               dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
+               kfree(txd);
+               return NULL;
+       }
+
+       sun6i_dma_cfg_lli(v_lli, src, dest, len, sconfig);
+       v_lli->cfg |= DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
+               DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
+               DMA_CHAN_CFG_DST_LINEAR_MODE |
+               DMA_CHAN_CFG_SRC_LINEAR_MODE;
+
+       sun6i_dma_lli_add(NULL, v_lli, p_lli, txd);
+
+       sun6i_dma_dump_lli(vchan, v_lli);
+
+       return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
+               struct dma_chan *chan, struct scatterlist *sgl,
+               unsigned int sg_len, enum dma_transfer_direction dir,
+               unsigned long flags, void *context)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       struct dma_slave_config *sconfig = &vchan->cfg;
+       struct sun6i_dma_lli *v_lli, *prev = NULL;
+       struct sun6i_desc *txd;
+       struct scatterlist *sg;
+       dma_addr_t p_lli;
+       int i;
+
+       if (!sgl)
+               return NULL;
+
+       if (!is_slave_direction(dir)) {
+               dev_err(chan2dev(chan), "Invalid DMA direction\n");
+               return NULL;
+       }
+
+       txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+       if (!txd)
+               return NULL;
+
+       for_each_sg(sgl, sg, sg_len, i) {
+               v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
+               if (!v_lli) {
+                       kfree(txd);
+                       return NULL;
+               }
+
+               if (dir == DMA_MEM_TO_DEV) {
+                       sun6i_dma_cfg_lli(v_lli, sg_dma_address(sg),
+                                         sconfig->dst_addr, sg_dma_len(sg),
+                                         sconfig);
+                       v_lli->cfg |= DMA_CHAN_CFG_DST_IO_MODE |
+                               DMA_CHAN_CFG_SRC_LINEAR_MODE |
+                               DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
+                               DMA_CHAN_CFG_DST_DRQ(vchan->port);
+
+                       dev_dbg(chan2dev(chan),
+                               "%s; chan: %d, dest: %pad, src: %pad, len: %zu. 
flags: 0x%08lx\n",
+                               __func__, vchan->vc.chan.chan_id,
+                               &sconfig->dst_addr, &sg_dma_address(sg),
+                               sg_dma_len(sg), flags);
+
+               } else {
+                       sun6i_dma_cfg_lli(v_lli, sconfig->src_addr,
+                                         sg_dma_address(sg), sg_dma_len(sg),
+                                         sconfig);
+                       v_lli->cfg |= DMA_CHAN_CFG_DST_LINEAR_MODE |
+                               DMA_CHAN_CFG_SRC_IO_MODE |
+                               DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
+                               DMA_CHAN_CFG_SRC_DRQ(vchan->port);
+
+                       dev_dbg(chan2dev(chan),
+                               "%s; chan: %d, dest: %pad, src: %pad, len: %zu. 
flags: 0x%08lx\n",
+                               __func__, vchan->vc.chan.chan_id,
+                               &sg_dma_address(sg), &sconfig->src_addr,
+                               sg_dma_len(sg), flags);
+               }
+
+               prev = sun6i_dma_lli_add(prev, v_lli, p_lli, txd);
+       }
+
+#ifdef DEBUG
+       dev_dbg(chan2dev(chan), "First: %pad\n", &txd->p_lli);
+       for (prev = txd->v_lli; prev != NULL; prev = prev->v_lli_next)
+               sun6i_dma_dump_lli(vchan, prev);
+#endif
+
+       return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
+}
+
+static int sun6i_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+                      unsigned long arg)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       struct sun6i_pchan *pchan = vchan->phy;
+       unsigned long flags;
+       int ret = 0;
+
+       switch (cmd) {
+       case DMA_RESUME:
+               dev_dbg(chan2dev(chan), "vchan %p: resume\n", &vchan->vc);
+
+               spin_lock_irqsave(&vchan->vc.lock, flags);
+
+               if (pchan) {
+                       writel(DMA_CHAN_PAUSE_RESUME,
+                              pchan->base + DMA_CHAN_PAUSE);
+               } else if (!list_empty(&vchan->vc.desc_issued)) {
+                       spin_lock(&sdev->lock);
+                       list_add_tail(&vchan->node, &sdev->pending);
+                       spin_unlock(&sdev->lock);
+               }
+
+               spin_unlock_irqrestore(&vchan->vc.lock, flags);
+               break;
+
+       case DMA_PAUSE:
+               dev_dbg(chan2dev(chan), "vchan %p: pause\n", &vchan->vc);
+
+               if (pchan) {
+                       writel(DMA_CHAN_PAUSE_PAUSE,
+                              pchan->base + DMA_CHAN_PAUSE);
+               } else {
+                       spin_lock(&sdev->lock);
+                       list_del_init(&vchan->node);
+                       spin_unlock(&sdev->lock);
+               }
+               break;
+
+       case DMA_TERMINATE_ALL:
+               ret = sun6i_dma_terminate_all(vchan);
+               break;
+       case DMA_SLAVE_CONFIG:
+               memcpy(&vchan->cfg, (struct dma_slave_config *)arg,
+                      sizeof(struct dma_slave_config));
+               break;
+       default:
+               ret = -ENXIO;
+               break;
+       }
+       return ret;
+}
+
+static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan,
+                                          dma_cookie_t cookie,
+                                          struct dma_tx_state *state)
+{
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       struct sun6i_pchan *pchan = vchan->phy;
+       struct sun6i_dma_lli *lli;
+       struct virt_dma_desc *vd;
+       struct sun6i_desc *txd;
+       enum dma_status ret;
+       unsigned long flags;
+       size_t bytes = 0;
+
+       ret = dma_cookie_status(chan, cookie, state);
+       if (ret == DMA_COMPLETE)
+               return ret;
+
+       spin_lock_irqsave(&vchan->vc.lock, flags);
+
+       vd = vchan_find_desc(&vchan->vc, cookie);
+       txd = to_sun6i_desc(&vd->tx);
+
+       if (vd) {
+               for (lli = txd->v_lli; lli != NULL; lli = lli->v_lli_next)
+                       bytes += lli->len;
+       } else if (!pchan || !pchan->desc) {
+               bytes = 0;
+       } else {
+               bytes = readl(pchan->base + DMA_CHAN_CUR_CNT);
+       }
+
+       spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+       dma_set_residue(state, bytes);
+
+       return ret;
+}
+
+static void sun6i_dma_issue_pending(struct dma_chan *chan)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       unsigned long flags;
+
+       spin_lock_irqsave(&vchan->vc.lock, flags);
+
+       if (vchan_issue_pending(&vchan->vc)) {
+               spin_lock(&sdev->lock);
+
+               if (!vchan->phy && list_empty(&vchan->node)) {
+                       list_add_tail(&vchan->node, &sdev->pending);
+                       tasklet_schedule(&sdev->task);
+                       dev_dbg(chan2dev(chan), "vchan %p: issued\n",
+                               &vchan->vc);
+               }
+
+               spin_unlock(&sdev->lock);
+       } else {
+               dev_dbg(chan2dev(chan), "vchan %p: nothing to issue\n",
+                       &vchan->vc);
+       }
+
+       spin_unlock_irqrestore(&vchan->vc.lock, flags);
+}
+
+static int sun6i_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+       return 0;
+}
+
+static void sun6i_dma_free_chan_resources(struct dma_chan *chan)
+{
+       struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+       struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+       unsigned long flags;
+
+       spin_lock_irqsave(&sdev->lock, flags);
+       list_del_init(&vchan->node);
+       spin_unlock_irqrestore(&sdev->lock, flags);
+
+       vchan_free_chan_resources(&vchan->vc);
+}
+
+static inline void sun6i_dma_free(struct sun6i_dma_dev *sdc)
+{
+       int i;
+
+       for (i = 0; i < NR_MAX_VCHANS; i++) {
+               struct sun6i_vchan *vchan = &sdc->vchans[i];
+
+               list_del(&vchan->vc.chan.device_node);
+               tasklet_kill(&vchan->vc.task);
+       }
+
+       tasklet_kill(&sdc->task);
+}
+
+static struct dma_chan *sun6i_dma_of_xlate(struct of_phandle_args *dma_spec,
+                                          struct of_dma *ofdma)
+{
+       struct sun6i_dma_dev *sdev = ofdma->of_dma_data;
+       struct sun6i_vchan *vchan;
+       struct dma_chan *chan;
+       u8 port = dma_spec->args[0];
+
+       if (port > NR_MAX_REQUESTS)
+               return NULL;
+
+       chan = dma_get_any_slave_channel(&sdev->slave);
+       if (!chan)
+               return NULL;
+
+       vchan = to_sun6i_vchan(chan);
+       vchan->port = port;
+
+       return chan;
+}
+
+static int sun6i_dma_probe(struct platform_device *pdev)
+{
+       struct sun6i_dma_dev *sdc;
+       struct resource *res;
+       struct clk *mux, *pll6;
+       int irq;
+       int ret, i;
+
+       sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
+       if (!sdc)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       sdc->base = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(sdc->base))
+               return PTR_ERR(sdc->base);
+
+       irq = platform_get_irq(pdev, 0);
+       ret = devm_request_irq(&pdev->dev, irq, sun6i_dma_interrupt, 0,
+                              dev_name(&pdev->dev), sdc);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot request IRQ\n");
+               return ret;
+       }
+
+       sdc->clk = devm_clk_get(&pdev->dev, NULL);
+       if (IS_ERR(sdc->clk)) {
+               dev_err(&pdev->dev, "No clock specified\n");
+               return PTR_ERR(sdc->clk);
+       }
+
+       mux = devm_clk_get(&pdev->dev, "ahb1_mux");
+       if (IS_ERR(mux)) {
+               dev_err(&pdev->dev, "Couldn't get AHB1 Mux\n");
+               return PTR_ERR(mux);
+       }
+
+       pll6 = devm_clk_get(&pdev->dev, "pll6");
+       if (IS_ERR(pll6)) {
+               dev_err(&pdev->dev, "Couldn't get PLL6\n");
+               return PTR_ERR(pll6);
+       }
+
+       ret = clk_set_parent(mux, pll6);
+       if (ret) {
+               dev_err(&pdev->dev, "Couldn't reparent AHB1 on PLL6\n");
+               return ret;
+       }
+
+       devm_clk_put(&pdev->dev, mux);
+       devm_clk_put(&pdev->dev, pll6);
+
+       sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
+       if (IS_ERR(sdc->rstc)) {
+               dev_err(&pdev->dev, "No reset controller specified\n");
+               return PTR_ERR(sdc->rstc);
+       }
+
+       sdc->pool = dmam_pool_create(dev_name(&pdev->dev), &pdev->dev,
+                                    sizeof(struct sun6i_dma_lli), 4, 0);
+       if (!sdc->pool) {
+               dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
+               return -ENOMEM;
+       }
+
+       platform_set_drvdata(pdev, sdc);
+       INIT_LIST_HEAD(&sdc->pending);
+       spin_lock_init(&sdc->lock);
+
+       dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask);
+       dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask);
+       dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask);
+
+       INIT_LIST_HEAD(&sdc->slave.channels);
+       sdc->slave.device_alloc_chan_resources  = 
sun6i_dma_alloc_chan_resources;
+       sdc->slave.device_free_chan_resources   = sun6i_dma_free_chan_resources;
+       sdc->slave.device_tx_status             = sun6i_dma_tx_status;
+       sdc->slave.device_issue_pending         = sun6i_dma_issue_pending;
+       sdc->slave.device_prep_slave_sg         = sun6i_dma_prep_slave_sg;
+       sdc->slave.device_prep_dma_memcpy       = sun6i_dma_prep_dma_memcpy;
+       sdc->slave.device_control               = sun6i_dma_control;
+       sdc->slave.chancnt                      = NR_MAX_VCHANS;
+
+       sdc->slave.dev = &pdev->dev;
+
+       sdc->pchans = devm_kcalloc(&pdev->dev, NR_MAX_CHANNELS,
+                                  sizeof(struct sun6i_pchan), GFP_KERNEL);
+       if (!sdc->pchans)
+               return -ENOMEM;
+
+       sdc->vchans = devm_kcalloc(&pdev->dev, NR_MAX_VCHANS,
+                                  sizeof(struct sun6i_vchan), GFP_KERNEL);
+       if (!sdc->vchans)
+               return -ENOMEM;
+
+       tasklet_init(&sdc->task, sun6i_dma_tasklet, (unsigned long)sdc);
+
+       for (i = 0; i < NR_MAX_CHANNELS; i++) {
+               struct sun6i_pchan *pchan = &sdc->pchans[i];
+
+               pchan->idx = i;
+               pchan->base = sdc->base + 0x100 + i * 0x40;
+       }
+
+       for (i = 0; i < NR_MAX_VCHANS; i++) {
+               struct sun6i_vchan *vchan = &sdc->vchans[i];
+
+               INIT_LIST_HEAD(&vchan->node);
+               vchan->vc.desc_free = sun6i_dma_free_desc;
+               vchan_init(&vchan->vc, &sdc->slave);
+       }
+
+       ret = reset_control_deassert(sdc->rstc);
+       if (ret) {
+               dev_err(&pdev->dev, "Couldn't deassert the device from 
reset\n");
+               goto err_chan_free;
+       }
+
+       ret = clk_prepare_enable(sdc->clk);
+       if (ret) {
+               dev_err(&pdev->dev, "Couldn't enable the clock\n");
+               goto err_reset_assert;
+       }
+
+       ret = dma_async_device_register(&sdc->slave);
+       if (ret) {
+               dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
+               goto err_clk_disable;
+       }
+
+       ret = of_dma_controller_register(pdev->dev.of_node, sun6i_dma_of_xlate,
+                                        sdc);
+       if (ret) {
+               dev_err(&pdev->dev, "of_dma_controller_register failed\n");
+               goto err_dma_unregister;
+       }
+
+       return 0;
+
+err_dma_unregister:
+       dma_async_device_unregister(&sdc->slave);
+err_clk_disable:
+       clk_disable_unprepare(sdc->clk);
+err_reset_assert:
+       reset_control_assert(sdc->rstc);
+err_chan_free:
+       sun6i_dma_free(sdc);
+       return ret;
+}
+
+static int sun6i_dma_remove(struct platform_device *pdev)
+{
+       struct sun6i_dma_dev *sdc = platform_get_drvdata(pdev);
+
+       of_dma_controller_free(pdev->dev.of_node);
+       dma_async_device_unregister(&sdc->slave);
+
+       clk_disable_unprepare(sdc->clk);
+       reset_control_assert(sdc->rstc);
+
+       sun6i_dma_free(sdc);
+
+       return 0;
+}
+
+static struct of_device_id sun6i_dma_match[] = {
+       { .compatible = "allwinner,sun6i-a31-dma" }
+};
+
+static struct platform_driver sun6i_dma_driver = {
+       .probe          = sun6i_dma_probe,
+       .remove         = sun6i_dma_remove,
+       .driver = {
+               .name           = "sun6i-dma",
+               .of_match_table = sun6i_dma_match,
+       },
+};
+module_platform_driver(sun6i_dma_driver);
+
+MODULE_DESCRIPTION("Allwinner A31 DMA Controller Driver");
+MODULE_AUTHOR("Sugar <sh...@allwinnertech.com>");
+MODULE_AUTHOR("Maxime Ripard <maxime.rip...@free-electrons.com>");
+MODULE_LICENSE("GPL");
-- 
1.9.0

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