[PATCHv6] dmaengine: Add support for BCM2835
Florian Meier
florian.meier at koalo.de
Fri Nov 15 12:35:07 EST 2013
Add support for DMA controller of BCM2835 as used in the Raspberry Pi.
Currently it only supports cyclic DMA.
Signed-off-by: Florian Meier <florian.meier at koalo.de>
---
Sixth version with some style improvements by Joe.
sizeof(s128) doesn't work. Therefore, still hardcoded byte counts.
.../devicetree/bindings/dma/bcm2835-dma.txt | 56 ++
drivers/dma/Kconfig | 6 +
drivers/dma/Makefile | 1 +
drivers/dma/bcm2835-dma.c | 744 +++++++++++++++++++++
4 files changed, 807 insertions(+)
create mode 100644 Documentation/devicetree/bindings/dma/bcm2835-dma.txt
create mode 100644 drivers/dma/bcm2835-dma.c
diff --git a/Documentation/devicetree/bindings/dma/bcm2835-dma.txt b/Documentation/devicetree/bindings/dma/bcm2835-dma.txt
new file mode 100644
index 0000000..7d91019
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/bcm2835-dma.txt
@@ -0,0 +1,56 @@
+* BCM2835 DMA controller
+
+Required properties:
+- compatible: Should be "brcm,bcm2835-dma".
+- reg: Should contain DMA registers location and length.
+- interrupts: Should contain the DMA interrupts associated
+ to the DMA channels in ascending order.
+ First cell is the IRQ bank.
+ Second cell is the IRQ number.
+- #dma-cells: Must be <1>, used to represent the number of integer cells in
+ the dmas property of client devices.
+- brcm,dma-channel-mask: Bit mask representing the channels
+ not used by the firmware.
+
+Example:
+
+dma: dma at 7e007000 {
+ compatible = "brcm,bcm2835-dma";
+ reg = <0x7e007000 0xf00>;
+ interrupts = <1 16
+ 1 17
+ 1 18
+ 1 19
+ 1 20
+ 1 21
+ 1 22
+ 1 23
+ 1 24
+ 1 25
+ 1 26
+ 1 27
+ 1 28>;
+
+ #dma-cells = <1>;
+ brcm,dma-channel-mask = <0x7f35>;
+};
+
+DMA clients connected to the BCM2835 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 DREQ number.
+
+Example:
+
+bcm2835_i2s: i2s at 7e203000 {
+ compatible = "brcm,bcm2835-i2s";
+ reg = < 0x7e203000 0x20
+ 0x7e101098 0x02>;
+
+ dmas = <&dma 2
+ &dma 3>;
+ dma-names = "tx", "rx";
+};
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index c61a6ec..880e723 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -300,6 +300,12 @@ config DMA_OMAP
select DMA_ENGINE
select DMA_VIRTUAL_CHANNELS
+config DMA_BCM2835
+ tristate "BCM2835 DMA engine support"
+ depends on (ARCH_BCM2835 || MACH_BCM2708)
+ select DMA_ENGINE
+ select DMA_VIRTUAL_CHANNELS
+
config TI_CPPI41
tristate "AM33xx CPPI41 DMA support"
depends on ARCH_OMAP
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 0ce2da9..0a6f08e 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_EP93XX_DMA) += ep93xx_dma.o
obj-$(CONFIG_DMA_SA11X0) += sa11x0-dma.o
obj-$(CONFIG_MMP_TDMA) += mmp_tdma.o
obj-$(CONFIG_DMA_OMAP) += omap-dma.o
+obj-$(CONFIG_DMA_BCM2835) += bcm2835-dma.o
obj-$(CONFIG_MMP_PDMA) += mmp_pdma.o
obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
obj-$(CONFIG_TI_CPPI41) += cppi41.o
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
new file mode 100644
index 0000000..23c7fb6
--- /dev/null
+++ b/drivers/dma/bcm2835-dma.c
@@ -0,0 +1,744 @@
+/*
+ * BCM2835 DMA engine support
+ *
+ * This driver only supports cyclic DMA transfers
+ * as needed for the I2S module.
+ *
+ * Author: Florian Meier, <florian.meier at koalo.de>
+ * Copyright 2013
+ *
+ * based on
+ * OMAP DMAengine support by Russell King
+ *
+ * BCM2708 DMA Driver
+ * Copyright (C) 2010 Broadcom
+ *
+ * Raspberry Pi PCM I2S ALSA Driver
+ * Copyright (c) by Phil Poole 2013
+ *
+ * MARVELL MMP Peripheral DMA Driver
+ * Copyright 2012 Marvell International Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+
+#include "virt-dma.h"
+
+struct bcm2835_dmadev {
+ struct dma_device ddev;
+ spinlock_t lock;
+ void __iomem *dma_base;
+ struct device_dma_parameters dma_parms;
+};
+
+struct bcm2835_dma_cb {
+ uint32_t info;
+ uint32_t src;
+ uint32_t dst;
+ uint32_t length;
+ uint32_t stride;
+ uint32_t next;
+ uint32_t pad[2];
+};
+
+struct bcm2835_chan {
+ struct virt_dma_chan vc;
+ struct list_head node;
+
+ struct dma_slave_config cfg;
+ bool cyclic;
+ unsigned dreq;
+
+ int dma_ch;
+ struct bcm2835_desc *desc;
+
+ void __iomem *dma_chan_base;
+ int dma_irq_number;
+};
+
+struct bcm2835_desc {
+ struct virt_dma_desc vd;
+ enum dma_transfer_direction dir;
+
+ unsigned int control_block_size;
+ struct bcm2835_dma_cb *control_block_base;
+ dma_addr_t control_block_base_phys;
+
+ unsigned frames;
+ size_t size;
+};
+
+#define BCM2835_DMA_CS 0x00
+#define BCM2835_DMA_ADDR 0x04
+#define BCM2835_DMA_SOURCE_AD 0x0c
+#define BCM2835_DMA_DEST_AD 0x10
+#define BCM2835_DMA_NEXTCB 0x1C
+
+/* DMA CS Control and Status bits */
+#define BCM2835_DMA_ACTIVE BIT(0)
+#define BCM2835_DMA_INT BIT(2)
+#define BCM2835_DMA_ISPAUSED BIT(4) /* Pause requested or not active */
+#define BCM2835_DMA_ISHELD BIT(5) /* Is held by DREQ flow control */
+#define BCM2835_DMA_ERR BIT(8)
+#define BCM2835_DMA_ABORT BIT(30) /* stop current CB, go to next, WO */
+#define BCM2835_DMA_RESET BIT(31) /* WO, self clearing */
+
+#define BCM2835_DMA_INT_EN BIT(0)
+#define BCM2835_DMA_D_INC BIT(4)
+#define BCM2835_DMA_D_DREQ BIT(6)
+#define BCM2835_DMA_S_INC BIT(8)
+#define BCM2835_DMA_S_DREQ BIT(10)
+
+#define BCM2835_DMA_PER_MAP(x) ((x) << 16)
+
+#define BCM2835_DMA_DATA_TYPE_S8 1
+#define BCM2835_DMA_DATA_TYPE_S16 2
+#define BCM2835_DMA_DATA_TYPE_S32 4
+#define BCM2835_DMA_DATA_TYPE_S128 16
+
+/* valid only for channels 0 - 14, 15 has its own base address */
+#define BCM2835_DMA_CHAN(n) ((n) << 8) /* base address */
+#define BCM2835_DMA_CHANIO(dma_base, n) ((dma_base) + BCM2835_DMA_CHAN(n))
+
+static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
+{
+ return container_of(d, struct bcm2835_dmadev, ddev);
+}
+
+static inline struct bcm2835_chan *to_bcm2835_dma_chan(struct dma_chan *c)
+{
+ return container_of(c, struct bcm2835_chan, vc.chan);
+}
+
+static inline struct bcm2835_desc *to_bcm2835_dma_desc(
+ struct dma_async_tx_descriptor *t)
+{
+ return container_of(t, struct bcm2835_desc, vd.tx);
+}
+
+static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
+{
+ struct bcm2835_desc *desc = container_of(vd, struct bcm2835_desc, vd);
+ dma_free_coherent(desc->vd.tx.chan->device->dev,
+ desc->control_block_size,
+ desc->control_block_base,
+ desc->control_block_base_phys);
+ kfree(desc);
+}
+
+static int bcm2835_dma_abort(void __iomem *dma_chan_base)
+{
+ unsigned long int cs;
+ long int timeout = 10000;
+
+ cs = readl(dma_chan_base + BCM2835_DMA_CS);
+ if (!(cs & BCM2835_DMA_ACTIVE))
+ return 0;
+
+ /* write 0 to the active bit - pause the DMA */
+ writel(0, dma_chan_base + BCM2835_DMA_CS);
+
+ /* wait for any current AXI transfer to complete */
+ while ((cs & BCM2835_DMA_ISPAUSED) && --timeout >= 0)
+ cs = readl(dma_chan_base + BCM2835_DMA_CS);
+
+ /* we'll un-pause when we set of our next DMA */
+ if (cs & BCM2835_DMA_ISPAUSED)
+ return -ETIMEDOUT;
+
+ if (!(cs & BCM2835_DMA_ACTIVE))
+ return 0;
+
+ /* terminate the control block chain */
+ writel(0, dma_chan_base + BCM2835_DMA_NEXTCB);
+
+ /* abort the whole DMA */
+ writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
+ dma_chan_base + BCM2835_DMA_CS);
+
+ return 0;
+}
+
+static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
+{
+ struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
+ struct bcm2835_desc *d;
+
+ if (!vd) {
+ c->desc = NULL;
+ return;
+ }
+
+ list_del(&vd->node);
+
+ c->desc = d = to_bcm2835_dma_desc(&vd->tx);
+
+ dsb(); /* ARM data synchronization (push) operation */
+
+ writel(d->control_block_base_phys, c->dma_chan_base + BCM2835_DMA_ADDR);
+ writel(BCM2835_DMA_ACTIVE, c->dma_chan_base + BCM2835_DMA_CS);
+}
+
+static irqreturn_t bcm2835_dma_callback(int irq, void *data)
+{
+ struct bcm2835_chan *c = data;
+ struct bcm2835_desc *d;
+ unsigned long flags;
+
+ spin_lock_irqsave(&c->vc.lock, flags);
+
+ /* acknowledge interrupt */
+ writel(BCM2835_DMA_INT, c->dma_chan_base + BCM2835_DMA_CS);
+
+ d = c->desc;
+
+ if (d) {
+ /* TODO Only works for cyclic DMA */
+ vchan_cyclic_callback(&d->vd);
+ }
+
+ /* keep the DMA engine running */
+ dsb(); /* ARM synchronization barrier */
+ writel(BCM2835_DMA_ACTIVE, c->dma_chan_base + BCM2835_DMA_CS);
+
+ spin_unlock_irqrestore(&c->vc.lock, flags);
+
+ return IRQ_HANDLED;
+}
+
+static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+
+ dev_dbg(c->vc.chan.device->dev,
+ "Allocating DMA channel %i\n", c->dma_ch);
+
+ return request_irq(c->dma_irq_number,
+ bcm2835_dma_callback, 0, "DMA IRQ", c);
+}
+
+static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+
+ vchan_free_chan_resources(&c->vc);
+ free_irq(c->dma_irq_number, c);
+
+ dev_dbg(c->vc.chan.device->dev, "Freeing DMA channel %u\n", c->dma_ch);
+}
+
+static size_t bcm2835_dma_desc_size(struct bcm2835_desc *d)
+{
+ return d->size;
+}
+
+static size_t bcm2835_dma_desc_size_pos(struct bcm2835_desc *d, dma_addr_t addr)
+{
+ unsigned i;
+ size_t size = 0;
+
+ for (i = 0; i < d->frames; i++) {
+ struct bcm2835_dma_cb *control_block =
+ &d->control_block_base[i];
+ size_t this_size = control_block->length;
+ dma_addr_t dma;
+
+ if (d->dir == DMA_DEV_TO_MEM)
+ dma = control_block->dst;
+ else
+ dma = control_block->src;
+
+ if (size)
+ size += this_size;
+ else if (addr >= dma && addr < dma + this_size)
+ size += dma + this_size - addr;
+ }
+
+ return size;
+}
+
+static enum dma_status bcm2835_dma_tx_status(struct dma_chan *chan,
+ dma_cookie_t cookie, struct dma_tx_state *txstate)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ struct virt_dma_desc *vd;
+ enum dma_status ret;
+ unsigned long flags;
+
+ ret = dma_cookie_status(chan, cookie, txstate);
+ if (ret == DMA_SUCCESS || !txstate)
+ return ret;
+
+ spin_lock_irqsave(&c->vc.lock, flags);
+ vd = vchan_find_desc(&c->vc, cookie);
+ if (vd) {
+ txstate->residue =
+ bcm2835_dma_desc_size(to_bcm2835_dma_desc(&vd->tx));
+ } else if (c->desc && c->desc->vd.tx.cookie == cookie) {
+ struct bcm2835_desc *d = c->desc;
+ dma_addr_t pos;
+
+ if (d->dir == DMA_MEM_TO_DEV)
+ pos = readl(c->dma_chan_base + BCM2835_DMA_SOURCE_AD);
+ else if (d->dir == DMA_DEV_TO_MEM)
+ pos = readl(c->dma_chan_base + BCM2835_DMA_DEST_AD);
+ else
+ pos = 0;
+
+ txstate->residue = bcm2835_dma_desc_size_pos(d, pos);
+ } else {
+ txstate->residue = 0;
+ }
+
+ spin_unlock_irqrestore(&c->vc.lock, flags);
+
+ return ret;
+}
+
+static void bcm2835_dma_issue_pending(struct dma_chan *chan)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ unsigned long flags;
+
+ c->cyclic = true; /* nothing else is implemented */
+
+ spin_lock_irqsave(&c->vc.lock, flags);
+ if (vchan_issue_pending(&c->vc) && !c->desc)
+ bcm2835_dma_start_desc(c);
+
+ spin_unlock_irqrestore(&c->vc.lock, flags);
+}
+
+
+static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
+ struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
+ size_t period_len, enum dma_transfer_direction direction,
+ unsigned long flags, void *context)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ enum dma_slave_buswidth dev_width;
+ struct bcm2835_desc *d;
+ dma_addr_t dev_addr;
+ unsigned es, sync_type;
+ unsigned frame;
+
+ /* Grab configuration */
+ if (direction == DMA_DEV_TO_MEM) {
+ dev_addr = c->cfg.src_addr;
+ dev_width = c->cfg.src_addr_width;
+ sync_type = BCM2835_DMA_S_DREQ;
+ } else if (direction == DMA_MEM_TO_DEV) {
+ dev_addr = c->cfg.dst_addr;
+ dev_width = c->cfg.dst_addr_width;
+ sync_type = BCM2835_DMA_D_DREQ;
+ } else {
+ dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
+ return NULL;
+ }
+
+ /* Bus width translates to the element size (ES) */
+ switch (dev_width) {
+ case DMA_SLAVE_BUSWIDTH_4_BYTES:
+ es = BCM2835_DMA_DATA_TYPE_S32;
+ break;
+ default:
+ return NULL;
+ }
+
+ /* Now allocate and setup the descriptor. */
+ d = kzalloc(sizeof(*d), GFP_NOWAIT);
+ if (!d)
+ return NULL;
+
+ d->dir = direction;
+ d->frames = buf_len / period_len;
+
+ /* Allocate memory for control blocks */
+ d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb);
+ d->control_block_base = dma_zalloc_coherent(chan->device->dev,
+ d->control_block_size, &d->control_block_base_phys,
+ GFP_NOWAIT);
+
+ if (!d->control_block_base) {
+ kfree(d);
+ return NULL;
+ }
+
+ /*
+ * Iterate over all frames, create a control block
+ * for each frame and link them together.
+ */
+ for (frame = 0; frame < d->frames; frame++) {
+ struct bcm2835_dma_cb *control_block =
+ &d->control_block_base[frame];
+
+ /* Setup adresses */
+ if (d->dir == DMA_DEV_TO_MEM) {
+ control_block->info = BCM2835_DMA_D_INC;
+ control_block->src = dev_addr;
+ control_block->dst = buf_addr + frame * period_len;
+ } else {
+ control_block->info = BCM2835_DMA_S_INC;
+ control_block->src = buf_addr + frame * period_len;
+ control_block->dst = dev_addr;
+ }
+
+ /* Enable interrupt */
+ control_block->info |= BCM2835_DMA_INT_EN;
+
+ /* Setup synchronization */
+ if (sync_type != 0)
+ control_block->info |= sync_type;
+
+ /* Setup DREQ channel */
+ if (c->dreq != 0)
+ control_block->info |=
+ BCM2835_DMA_PER_MAP(c->dreq);
+
+ /* Length of a frame */
+ control_block->length = period_len;
+ d->size += control_block->length;
+
+ /*
+ * Next block is the next frame.
+ * This DMA engine driver currently only supports cyclic DMA.
+ * Therefore, wrap around at number of frames.
+ */
+ control_block->next = d->control_block_base_phys +
+ sizeof(struct bcm2835_dma_cb)
+ * ((frame + 1) % d->frames);
+
+ /* The following fields are not used here */
+ control_block->stride = 0;
+ control_block->pad[0] = 0;
+ control_block->pad[1] = 0;
+ }
+
+ return vchan_tx_prep(&c->vc, &d->vd, flags);
+}
+
+static int bcm2835_dma_slave_config(struct bcm2835_chan *c,
+ struct dma_slave_config *cfg)
+{
+ if ((cfg->direction == DMA_DEV_TO_MEM &&
+ cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
+ (cfg->direction == DMA_MEM_TO_DEV &&
+ cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
+ (cfg->direction != DMA_DEV_TO_MEM &&
+ cfg->direction != DMA_MEM_TO_DEV)) {
+ return -EINVAL;
+ }
+
+ c->cfg = *cfg;
+
+ return 0;
+}
+
+static int bcm2835_dma_terminate_all(struct bcm2835_chan *c)
+{
+ struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
+ unsigned long flags;
+ int timeout = 1000;
+ LIST_HEAD(head);
+
+ spin_lock_irqsave(&c->vc.lock, flags);
+
+ /* Prevent this channel being scheduled */
+ spin_lock(&d->lock);
+ list_del_init(&c->node);
+ spin_unlock(&d->lock);
+
+ /*
+ * Stop DMA activity: we assume the callback will not be called
+ * after bcm_dma_abort() returns (even if it does, it will see
+ * c->desc is NULL and exit.)
+ */
+ if (c->desc) {
+ c->desc = NULL;
+ bcm2835_dma_abort(c->dma_chan_base);
+
+ /* Wait for stopping */
+ while (timeout > 0) {
+ timeout--;
+ if (!(readl(c->dma_chan_base + BCM2835_DMA_CS) &
+ BCM2835_DMA_ACTIVE))
+ break;
+
+ cpu_relax();
+ }
+
+ if (timeout <= 0)
+ dev_err(d->ddev.dev, "DMA transfer could not be terminated\n");
+ }
+
+ vchan_get_all_descriptors(&c->vc, &head);
+ spin_unlock_irqrestore(&c->vc.lock, flags);
+ vchan_dma_desc_free_list(&c->vc, &head);
+
+ return 0;
+}
+
+static int bcm2835_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+ unsigned long arg)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ int ret;
+
+ switch (cmd) {
+ case DMA_SLAVE_CONFIG:
+ return bcm2835_dma_slave_config(c,
+ (struct dma_slave_config *)arg);
+
+ case DMA_TERMINATE_ALL:
+ bcm2835_dma_terminate_all(c);
+ break;
+
+ default:
+ ret = -ENXIO;
+ break;
+ }
+
+ return ret;
+}
+
+static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, int irq)
+{
+ struct bcm2835_chan *c;
+
+ c = kzalloc(sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ c->vc.desc_free = bcm2835_dma_desc_free;
+ vchan_init(&c->vc, &d->ddev);
+ INIT_LIST_HEAD(&c->node);
+
+ d->ddev.chancnt++;
+
+ c->dma_chan_base = BCM2835_DMA_CHANIO(d->dma_base, chan_id);
+ c->dma_ch = chan_id;
+ c->dma_irq_number = irq;
+
+ return 0;
+}
+
+static void bcm2835_dma_free(struct bcm2835_dmadev *od)
+{
+ while (!list_empty(&od->ddev.channels)) {
+ struct bcm2835_chan *c = list_first_entry(&od->ddev.channels,
+ struct bcm2835_chan, vc.chan.device_node);
+
+ list_del(&c->vc.chan.device_node);
+ tasklet_kill(&c->vc.task);
+ kfree(c);
+ }
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id bcm2835_dma_of_match[] = {
+ { .compatible = "brcm,bcm2835-dma", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_dma_of_match);
+#endif
+
+static struct dma_chan *bcm2835_dma_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma)
+{
+ struct bcm2835_dmadev *d = ofdma->of_dma_data;
+ struct dma_chan *chan, *candidate;
+
+retry:
+ candidate = NULL;
+
+ /* walk the list of channels registered with the current instance and
+ * find one that is currently unused */
+ list_for_each_entry(chan, &d->ddev.channels, device_node)
+ if (chan->client_count == 0) {
+ candidate = chan;
+ break;
+ }
+
+ if (!candidate)
+ return NULL;
+
+ /* dma_get_slave_channel will return NULL if we lost a race between
+ * the lookup and the reservation */
+ chan = dma_get_slave_channel(candidate);
+
+ if (chan) {
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+
+ /* Set DREQ from param */
+ c->dreq = dma_spec->args[0];
+
+ return chan;
+ }
+
+ goto retry;
+}
+
+static int bcm2835_dma_device_slave_caps(struct dma_chan *dchan,
+ struct dma_slave_caps *caps)
+{
+ caps->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+ caps->dstn_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+ caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+ caps->cmd_pause = false;
+ caps->cmd_terminate = true;
+
+ return 0;
+}
+
+static int bcm2835_dma_probe(struct platform_device *pdev)
+{
+ struct bcm2835_dmadev *od;
+ struct resource *dma_res = NULL;
+ void __iomem *dma_base = NULL;
+ int rc = 0;
+ int i = 0;
+ int irq;
+ uint32_t chans_available;
+
+ if (!pdev->dev.dma_mask)
+ pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
+
+ rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
+ if (rc)
+ return rc;
+ dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+
+ od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
+ if (!od)
+ return -ENOMEM;
+
+ pdev->dev.dma_parms = &od->dma_parms;
+ dma_set_max_seg_size(&pdev->dev, 0x3FFFFFFF);
+
+ dma_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ dma_base = devm_ioremap_resource(&pdev->dev, dma_res);
+ if (IS_ERR(dma_base))
+ return PTR_ERR(dma_base);
+
+ od->dma_base = dma_base;
+
+ dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
+ dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
+ od->ddev.device_alloc_chan_resources = bcm2835_dma_alloc_chan_resources;
+ od->ddev.device_free_chan_resources = bcm2835_dma_free_chan_resources;
+ od->ddev.device_tx_status = bcm2835_dma_tx_status;
+ od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
+ od->ddev.device_slave_caps = bcm2835_dma_device_slave_caps;
+ od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
+ od->ddev.device_control = bcm2835_dma_control;
+ od->ddev.dev = &pdev->dev;
+ INIT_LIST_HEAD(&od->ddev.channels);
+ spin_lock_init(&od->lock);
+
+ platform_set_drvdata(pdev, od);
+
+ if (pdev->dev.of_node) {
+ /* Request DMA channel mask from device tree */
+ if (of_property_read_u32(pdev->dev.of_node,
+ "brcm,dma-channel-mask",
+ &chans_available)) {
+ dev_err(&pdev->dev, "Failed to get channel mask\n");
+ bcm2835_dma_free(od);
+ return -EINVAL;
+ }
+ } else {
+ dev_err(&pdev->dev, "Failed to get channel mask. No device tree.\n");
+ bcm2835_dma_free(od);
+ return -EINVAL;
+ }
+
+ /* do not use the FIQ and BULK channels */
+ chans_available &= ~0xD;
+
+ for (i = 0; i < pdev->num_resources; i++) {
+ irq = platform_get_irq(pdev, i);
+ if (irq < 0)
+ break;
+
+ if (chans_available & (1 << i)) {
+ rc = bcm2835_dma_chan_init(od, i, irq);
+ if (rc) {
+ bcm2835_dma_free(od);
+ return rc;
+ }
+ }
+ }
+
+ dev_dbg(&pdev->dev, "Initialized %i DMA channels\n", i);
+
+ if (pdev->dev.of_node) {
+ /* Device-tree DMA controller registration */
+ rc = of_dma_controller_register(pdev->dev.of_node,
+ bcm2835_dma_xlate, od);
+ if (rc) {
+ dev_err(&pdev->dev, "Failed to register DMA controller\n");
+ bcm2835_dma_free(od);
+ return rc;
+ }
+ }
+
+ rc = dma_async_device_register(&od->ddev);
+ if (rc) {
+ dev_err(&pdev->dev,
+ "Failed to register slave DMA engine device: %d\n", rc);
+ bcm2835_dma_free(od);
+ return rc;
+ }
+
+ dev_dbg(&pdev->dev, "Load BCM2835 DMA engine driver\n");
+
+ return rc;
+}
+
+static int bcm2835_dma_remove(struct platform_device *pdev)
+{
+ struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
+
+ dma_async_device_unregister(&od->ddev);
+ bcm2835_dma_free(od);
+
+ return 0;
+}
+
+static struct platform_driver bcm2835_dma_driver = {
+ .probe = bcm2835_dma_probe,
+ .remove = bcm2835_dma_remove,
+ .driver = {
+ .name = "bcm2835-dma",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(bcm2835_dma_of_match),
+ },
+};
+
+module_platform_driver(bcm2835_dma_driver);
+
+MODULE_ALIAS("platform:bcm2835-dma");
+MODULE_DESCRIPTION("BCM2835 DMA engine driver");
+MODULE_AUTHOR("Florian Meier <florian.meier at koalo.de>");
+MODULE_LICENSE("GPL v2");
--
1.8.1.2
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