Re: [RFC 1/2] usb/musb dma: add cppi41 dma driver

Sergei Shtylyov
2013-07-07T14:56:06Z

Hello.

On 05-07-2013 20:12, Sebastian Andrzej Siewior wrote:

> This is a first shot of the cppi41 DMA driver.

Where have you been when I submitted my drivers back in 2009? :-)

> It is currently used by
> a new musb dma-engine implementation. I have to test it somehow.

> The state of the cpp41 (and the using dmaengine) is in very early stage.
> I was able to send TX packets over DMA and enumerate an USB masstorage
> device.
> Things that need to be taken care of:
> - RX path
> - cancel of transfers
> - dynamic descriptor allocation
> - re-think the current device tree nodes.
> Currently a node looks like:
> &cppi41dma X Y Z Q
> that means:
> - X: dma channel
> - Y: RX/TX
> - Z: start queue
> - Q: complete queue
> Each value number is hardwired with the USB endpoint it is using. The
> DMA channels are hardwired with USB endpoints and the start/complete
> is hardwired with the DMA channel.

> I add each DMA channel twice: once for RX the other for TX (that is why
> I need the direction (Y) uppon lookup).
> The RX/TX channel can be used simultaneously i.e. program & start RX,
> program & start TX and TX can complete before RX.
> Currently I think that it would be best to remove the queue logic from
> the device and put it into the driver.

> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> arch/arm/boot/dts/am33xx.dtsi | 50 +++
> drivers/dma/Kconfig | 9 +
> drivers/dma/Makefile | 1 +
> drivers/dma/cppi41.c | 777 +++++++++++++++++++++++++++++++++++++++++
> drivers/usb/musb/Kconfig | 4 +
> drivers/usb/musb/Makefile | 1 +
> drivers/usb/musb/musb_dma.h | 2 +-
> drivers/usb/musb/musb_dmaeng.c | 294 ++++++++++++++++

MUSB DMA engine support can't be generic unfortunately. There are
some non-generic DMA registers in each MUSB implementation that used
CPPI 4.1.

> 8 files changed, 1137 insertions(+), 1 deletion(-)
> create mode 100644 drivers/dma/cppi41.c
> create mode 100644 drivers/usb/musb/musb_dmaeng.c
>
> diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi
> index bb2298c..fc29b54 100644
> --- a/arch/arm/boot/dts/am33xx.dtsi
> +++ b/arch/arm/boot/dts/am33xx.dtsi
> @@ -349,6 +349,18 @@
> status = "disabled";
> };
>
> + cppi41dma: dma@07402000 {

@47402000? maybe?

> + compatible = "ti,am3359-cppi41";
> + reg = <0x47400000 0x1000 /* usbss */

USB register are not a part of CPPI 4.1 DMA. They are not generic
and are different on e.g. DA8xx/OMAP-L1x. Besides this range is
conflicting with the next node.

> + 0x47402000 0x1000 /* controller */
> + 0x47403000 0x1000 /* scheduler */
> + 0x47404000 0x4000>; /* queue manager */
> + interrupts = <17>;
> + #dma-cells = <4>;
> + #dma-channels = <30>;
> + #dma-requests = <256>;
> + };
> +
> musb: usb@47400000 {
> compatible = "ti,musb-am33xx";
> reg = <0x47400000 0x1000>;
[...]
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 3215a3c..c19a593 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -305,6 +305,15 @@ config DMA_OMAP
> select DMA_ENGINE
> select DMA_VIRTUAL_CHANNELS
>
> +config TI_CPPI41
> + tristate "AM33xx CPPI41 DMA support"

It shouldn't be specific to AM33xx.

> + depends on ARCH_OMAP

And shouldn't depend on ARCH_OMAP only, also on ARCH_DAVINCI_DA8XX.

[...]
> diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
> new file mode 100644
> index 0000000..80dcb56
> --- /dev/null
> +++ b/drivers/dma/cppi41.c
> @@ -0,0 +1,777 @@
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/of_dma.h>
> +#include <linux/of_irq.h>
> +#include <linux/dmapool.h>
> +#include <linux/interrupt.h>
> +#include <linux/of_address.h>
> +#include "dmaengine.h"
> +
> +#define DESC_TYPE 27
> +#define DESC_TYPE_HOST 0x10
> +#define DESC_TYPE_TEARD 0x13
> +
> +#define TD_DESC_TX_RX 16
> +#define TD_DESC_DMA_NUM 10
> +
> +/* USB SS */
> +#define USBSS_IRQ_STATUS (0x28)
> +#define USBSS_IRQ_ENABLER (0x2c)
> +#define USBSS_IRQ_CLEARR (0x30)

These shouldn't be here. Why enclose them in () BTW?

> +
> +#define USBSS_IRQ_RX1 (1 << 11)
> +#define USBSS_IRQ_TX1 (1 << 10)
> +#define USBSS_IRQ_RX0 (1 << 9)
> +#define USBSS_IRQ_TX0 (1 << 8)
> +#define USBSS_IRQ_PD_COMP (1 << 2)
> +
> +#define USBSS_IRQ_RXTX1 (USBSS_IRQ_RX1 | USBSS_IRQ_TX1)
> +#define USBSS_IRQ_RXTX0 (USBSS_IRQ_RX0 | USBSS_IRQ_TX0)
> +#define USBSS_IRQ_RXTX01 (USBSS_IRQ_RXTX0 | USBSS_IRQ_RXTX1)
> +

Neither these shouldn't be here.

> +/* Queue manager */
> +/* 4 KiB of memory for descriptors, 2 for each endpoint */

Endpoints shouldn't be mentioned. CPPI 4.1 is universal DMA engine,
not USB specific.

> +struct cppi41_dd {
> + struct dma_device ddev;
> +
> + void *qmgr_scratch;
> + dma_addr_t scratch_phys;
> +
> + struct cppi41_desc *cd;
> + dma_addr_t descs_phys;
> + struct cppi41_channel *chan_busy[ALLOC_DECS_NUM];
> +
> + void __iomem *usbss_mem;

Shouldn't be here.

> + void __iomem *ctrl_mem;
> + void __iomem *sched_mem;
> + void __iomem *qmgr_mem;
> + unsigned int irq;

Shouldn't be here either.

> +static struct cppi41_channel *desc_to_chan(struct cppi41_dd *cdd, u32 desc)
> +{
> + struct cppi41_channel *c;
> + u32 descs_size;
> + u32 desc_num;
> +
> + descs_size = sizeof(struct cppi41_desc) * ALLOC_DECS_NUM;
> +
> + if (!((desc >= cdd->descs_phys) &&
> + (desc < (cdd->descs_phys + descs_size)))) {
> + return NULL;
> + }

checkpatch.pl would complain about single statement in {}.

> +static void cppi_writel(u32 val, void *__iomem *mem)
> +{
> + writel(val, mem);
> +}
> +
> +static u32 cppi_readl(void *__iomem *mem)
> +{
> + u32 val;
> + val = readl(mem);
> + return val;
> +}

I don't see much sense in these functions. Besides, they should
probably be using __raw_{read|write}().

> +static irqreturn_t cppi41_irq(int irq, void *data)
> +{
> + struct cppi41_dd *cdd = data;
> + struct cppi41_channel *c;
> + u32 status;
> + int i;
> +
> + status = cppi_readl(cdd->usbss_mem + USBSS_IRQ_STATUS);
> + if (!(status & USBSS_IRQ_PD_COMP))
> + return IRQ_NONE;

No, this can't be here.

> +static u32 get_host_pd0(u32 length)
> +{
> + u32 reg;
> +
> + reg = DESC_TYPE_HOST << DESC_TYPE;
> + reg |= length;
> +
> + return reg;
> +}
> +
> +static u32 get_host_pd1(struct cppi41_channel *c)
> +{
> + u32 reg;
> +
> + reg = 0;
> +
> + return reg;
> +}
> +
> +static u32 get_host_pd2(struct cppi41_channel *c)
> +{
> + u32 reg;
> +
> + reg = 5 << 26; /* USB TYPE */

The driver shouldn't be tied to USB at all.

> +static int cppi41_dma_probe(struct platform_device *pdev)
> +{
> + struct cppi41_dd *cdd;
> + int irq;
> + int ret;
> +
> + cdd = kzalloc(sizeof(*cdd), GFP_KERNEL);
> + if (!cdd)
> + return -ENOMEM;
> +
> + dma_cap_set(DMA_SLAVE, cdd->ddev.cap_mask);
> + cdd->ddev.device_alloc_chan_resources = cppi41_dma_alloc_chan_resources;
> + cdd->ddev.device_free_chan_resources = cppi41_dma_free_chan_resources;
> + cdd->ddev.device_tx_status = cppi41_dma_tx_status;
> + cdd->ddev.device_issue_pending = cppi41_dma_issue_pending;
> + cdd->ddev.device_prep_slave_sg = cppi41_dma_prep_slave_sg;
> + cdd->ddev.device_control = cppi41_dma_control;
> + cdd->ddev.dev = &pdev->dev;
> + INIT_LIST_HEAD(&cdd->ddev.channels);
> + cpp41_dma_info.dma_cap = cdd->ddev.cap_mask;
> +
> + cdd->usbss_mem = of_iomap(pdev->dev.of_node, 0);

You should use the generic platform_get_resource()/
devm_ioremap_resource() functions.

> + irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
> + if (!irq)
> + goto err_irq;
> +
> + cppi_writel(USBSS_IRQ_PD_COMP, cdd->usbss_mem + USBSS_IRQ_ENABLER);

Shouldn't be here.

[...]
> +static const struct of_device_id cppi41_dma_ids[] = {
> + { .compatible = "ti,am3359-cppi41", },

CPPI 4.1 driver should be generic, not SoC specific.

> diff --git a/drivers/usb/musb/musb_dma.h b/drivers/usb/musb/musb_dma.h
> index c8e67fd..bfe2993 100644
> --- a/drivers/usb/musb/musb_dma.h
> +++ b/drivers/usb/musb/musb_dma.h
> @@ -71,7 +71,7 @@ struct musb_hw_ep;
> #ifdef CONFIG_USB_TI_CPPI_DMA
> #define is_cppi_enabled() 1
> #else
> -#define is_cppi_enabled() 0
> +#define is_cppi_enabled() 1

What does that mean?

> diff --git a/drivers/usb/musb/musb_dmaeng.c b/drivers/usb/musb/musb_dmaeng.c
> new file mode 100644
> index 0000000..c12f42a
> --- /dev/null
> +++ b/drivers/usb/musb/musb_dmaeng.c
> @@ -0,0 +1,294 @@
[...]
> +static struct dma_channel *cppi41_dma_channel_allocate(struct dma_controller *c,
> + struct musb_hw_ep *hw_ep, u8 is_tx)
> +{
> + struct cppi41_dma_controller *controller = container_of(c,
> + struct cppi41_dma_controller, controller);
> + struct cppi41_dma_channel *cppi41_channel = NULL;
> + struct musb *musb = controller->musb;
> + u8 ch_num = hw_ep->epnum - 1;
> +
> + if (ch_num >= MUSB_DMA_NUM_CHANNELS)
> + return NULL;
> +
> + if (!is_tx)
> + return NULL;
> + if (is_tx)

You've just returned on '!is_tx'.

[...]
> +static void cppi41_release_all_dma_chans(struct cppi41_dma_controller *ctrl)
> +{
> + struct dma_chan *dc;
> + int i;
> +
> + for (i = 0; i < MUSB_DMA_NUM_CHANNELS; i++) {
> + dc = ctrl->tx_channel[i].dc;
> + if (dc)
> + dma_release_channel(dc);
> + dc = ctrl->rx_channel[i].dc;
> + if (dc)
> + dma_release_channel(dc);
> + }
> +}
> +
> +static void cppi41_dma_controller_stop(struct cppi41_dma_controller *controller)
> +{
> + cppi41_release_all_dma_chans(controller);

Why not just expand it inline?

> +}
> +
> +static int cppi41_dma_controller_start(struct cppi41_dma_controller *controller)
> +{
> + struct musb *musb = controller->musb;
> + struct device *dev = musb->controller;
> + struct device_node *np = dev->of_node;
> + struct cppi41_dma_channel *cppi41_channel;
> + int count;
> + int i;
> + int ret;
> + dma_cap_mask_t mask;
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);

You don't seem to use 'mask'.

[...]
> + musb_dma = &cppi41_channel->channel;
> + musb_dma->private_data = cppi41_channel;
> + musb_dma->status = MUSB_DMA_STATUS_FREE;
> + musb_dma->max_len = SZ_4M;

Really?

WBR, Sergei