Re: [PATCHv10] dmaengine: Add support for BCM2835
From: Andy Shevchenko
Date: Tue Jan 07 2014 - 10:20:37 EST
On Mon, 2014-01-06 at 20:18 +0100, Florian Meier wrote:
> 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@xxxxxxxx>
> ---
>
> Merging and rebasing was easier than I feared and
> I found an additional API change (DMA_SUCCESS).
>
> Andy: I would be happy to have your Reviewed-by again,
> but I removed it because of these changes.
Sure. Couple of minor comments below, anyway still seems okay for me:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>
> Changes compared to v9:
> - Added commas to device tree documentation
> - DMA_SUCCESS -> DMA_COMPLETE
> - Removed #if defined(CONFIG_OF)
> - Use of dma_get_any_slave_channel
> - Use of dma_set_mask_and_coherent
> - Removed if (pdev->dev.of_node) in probe
>
> .../devicetree/bindings/dma/bcm2835-dma.txt | 57 ++
> drivers/dma/Kconfig | 6 +
> drivers/dma/Makefile | 1 +
> drivers/dma/bcm2835-dma.c | 706 +++++++++++++++++++++
> 4 files changed, 770 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..1396078
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/bcm2835-dma.txt
> @@ -0,0 +1,57 @@
> +* BCM2835 DMA controller
> +
> +The BCM2835 DMA controller has 16 channels in total.
> +Only the lower 13 channels have an associated IRQ.
> +Some arbitrary channels are used by the firmware
> +(1,3,6,7 in the current firmware version).
> +The channels 0,2 and 3 have special functionality
> +and should not be used by the driver.
> +
> +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.
> +- #dma-cells: Must be <1>, the cell in the dmas property of the
> + client device represents the DREQ number.
> +- brcm,dma-channel-mask: Bit mask representing the channels
> + not used by the firmware in ascending order,
> + i.e. first channel corresponds to LSB.
> +
> +Example:
> +
> +dma: dma@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.
> +
> +Example:
> +
> +bcm2835_i2s: i2s@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 c823daa..6f74f8c 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -304,6 +304,12 @@ 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..6ae0708
> --- /dev/null
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -0,0 +1,706 @@
> +/*
> + * BCM2835 DMA engine support
> + *
> + * This driver only supports cyclic DMA transfers
> + * as needed for the I2S module.
> + *
> + * Author: Florian Meier <florian.meier@xxxxxxxx>
> + * 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 *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 int dreq;
> +
> + int ch;
> + struct bcm2835_desc *desc;
> +
> + void __iomem *chan_base;
> + int 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 int 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
> +
> +#define BCM2835_DMA_BULK_MASK BIT(0)
> +#define BCM2835_DMA_FIQ_MASK (BIT(2) | BIT(3))
> +
> +/* 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(base, n) ((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 *chan_base)
> +{
> + unsigned long cs;
> + long int timeout = 10000;
> +
> + cs = readl(chan_base + BCM2835_DMA_CS);
> + if (!(cs & BCM2835_DMA_ACTIVE))
> + return 0;
> +
> + /* Write 0 to the active bit - Pause the DMA */
> + writel(0, chan_base + BCM2835_DMA_CS);
> +
> + /* Wait for any current AXI transfer to complete */
> + while ((cs & BCM2835_DMA_ISPAUSED) && --timeout) {
> + cpu_relax();
> + cs = readl(chan_base + BCM2835_DMA_CS);
> + }
> +
> + /* We'll un-pause when we set of our next DMA */
> + if (!timeout)
> + return -ETIMEDOUT;
> +
> + if (!(cs & BCM2835_DMA_ACTIVE))
> + return 0;
> +
> + /* Terminate the control block chain */
> + writel(0, chan_base + BCM2835_DMA_NEXTCB);
> +
> + /* Abort the whole DMA */
> + writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
> + 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);
> +
> + writel(d->control_block_base_phys, c->chan_base + BCM2835_DMA_ADDR);
> + writel(BCM2835_DMA_ACTIVE, c->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->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 */
> + writel(BCM2835_DMA_ACTIVE, c->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 %d\n", c->ch);
> +
> + return request_irq(c->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->irq_number, c);
> +
> + dev_dbg(c->vc.chan.device->dev, "Freeing DMA channel %u\n", c->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 int i;
> + size_t size;
> +
> + for (size = 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_COMPLETE || !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->chan_base + BCM2835_DMA_SOURCE_AD);
> + else if (d->dir == DMA_DEV_TO_MEM)
> + pos = readl(c->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 int es, sync_type;
> + unsigned int frame;
> +
> + /* Grab configuration */
> + if (!is_slave_direction(direction)) {
> + dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
> + return NULL;
> + }
> +
> + 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 {
> + dev_addr = c->cfg.dst_addr;
> + dev_width = c->cfg.dst_addr_width;
> + sync_type = BCM2835_DMA_D_DREQ;
> + }
> +
> + /* 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);
> + }
> +
> + 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) ||
> + !is_slave_direction(cfg->direction)) {
> + 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 = 10000;
> + 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->chan_base);
> +
> + /* Wait for stopping */
> + while (--timeout) {
> + if (!(readl(c->chan_base + BCM2835_DMA_CS) &
> + BCM2835_DMA_ACTIVE))
> + break;
> +
> + cpu_relax();
> + }
> +
> + if (!timeout)
> + 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);
> +
> + switch (cmd) {
> + case DMA_SLAVE_CONFIG:
> + return bcm2835_dma_slave_config(c,
> + (struct dma_slave_config *)arg);
> +
> + case DMA_TERMINATE_ALL:
> + return bcm2835_dma_terminate_all(c);
> +
> + default:
> + return -ENXIO;
> + }
> +}
> +
> +static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, int irq)
> +{
> + struct bcm2835_chan *c;
> +
> + c = devm_kzalloc(d->ddev.dev, 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->chan_base = BCM2835_DMA_CHANIO(d->base, chan_id);
> + c->ch = chan_id;
> + c->irq_number = irq;
> +
> + return 0;
> +}
> +
> +static void bcm2835_dma_free(struct bcm2835_dmadev *od)
> +{
> + struct bcm2835_chan *c, *next;
> +
> + list_for_each_entry_safe(c, next, &od->ddev.channels,
> + vc.chan.device_node) {
> + list_del(&c->vc.chan.device_node);
> + tasklet_kill(&c->vc.task);
> + }
> +}
> +
> +static const struct of_device_id bcm2835_dma_of_match[] = {
> + { .compatible = "brcm,bcm2835-dma", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, bcm2835_dma_of_match);
> +
> +static struct dma_chan *bcm2835_dma_xlate(struct of_phandle_args *spec,
> + struct of_dma *ofdma)
> +{
> + struct bcm2835_dmadev *d = ofdma->of_dma_data;
> + struct dma_chan *chan;
> +
> + chan = dma_get_any_slave_channel(&d->ddev);
> + if (!chan)
> + return NULL;
> +
> + /* Set DREQ from param */
> + to_bcm2835_dma_chan(chan)->dreq = spec->args[0];
> +
> + return chan;
> +}
> +
> +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 *res;
> + void __iomem *base;
> + int rc;
> + int i;
> + int irq;
> + uint32_t chans_available;
> +
> + if (!pdev->dev.dma_mask)
> + pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
> +
> + rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> + if (rc)
> + return rc;
I'm not sure but you might even use dma_coerce_mask_and_coherent() here.
>
> +
> + 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);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + od->base = 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);
> +
> + /* 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");
> + rc = -EINVAL;
> + goto err_no_dma;
> + }
> +
> + /*
> + * Do not use the FIQ and BULK channels,
> + * because they are used by the GPU.
Could a text width be closer to 72-80 characters?
> + */
> + chans_available &= ~(BCM2835_DMA_FIQ_MASK | BCM2835_DMA_BULK_MASK);
> +
> + 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)
> + goto err_no_dma;
> + }
> + }
> +
> + dev_dbg(&pdev->dev, "Initialized %i DMA channels\n", i);
> +
> + /* 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");
> + goto err_no_dma;
> + }
> +
> + rc = dma_async_device_register(&od->ddev);
> + if (rc) {
> + dev_err(&pdev->dev,
> + "Failed to register slave DMA engine device: %d\n", rc);
> + goto err_no_dma;
> + }
> +
> + dev_dbg(&pdev->dev, "Load BCM2835 DMA engine driver\n");
> +
> + return 0;
> +
> +err_no_dma:
> + bcm2835_dma_free(od);
> + 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@xxxxxxxx>");
> +MODULE_LICENSE("GPL v2");
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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