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Date: Tue, 25 Dec 2018 20:06:51 +0800
From: Long Cheng <long.cheng@...iatek.com>
To: Nicolas Boichat <drinkcat@...omium.org>
CC: Vinod Koul <vkoul@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Rob Herring" <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
"Ryder Lee" <ryder.lee@...iatek.com>,
Sean Wang <sean.wang@...nel.org>,
"Matthias Brugger" <matthias.bgg@...il.com>,
Dan Williams <dan.j.williams@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>,
Sean Wang <sean.wang@...iatek.com>,
<dmaengine@...r.kernel.org>, <devicetree@...r.kernel.org>,
"linux-arm Mailing List" <linux-arm-kernel@...ts.infradead.org>,
<linux-mediatek@...ts.infradead.org>,
lkml <linux-kernel@...r.kernel.org>,
<linux-serial@...r.kernel.org>, <srv_heupstream@...iatek.com>,
Yingjoe Chen <yingjoe.chen@...iatek.com>,
YT Shen <yt.shen@...iatek.com>
Subject: Re: [PATCH v7 1/2] dmaengine: 8250_mtk_dma: add MediaTek uart DMA
support
Thanks for your comments.
On Tue, 2018-12-25 at 15:16 +0800, Nicolas Boichat wrote:
> Not a full review, a few comments below.
>
> Thanks,
>
would you like help to full review at this version patch? and then i
can modify these at next version patch. thanks.
> On Tue, Dec 25, 2018 at 9:27 AM Long Cheng <long.cheng@...iatek.com> wrote:
> >
> > In DMA engine framework, add 8250 uart dma to support MediaTek uart.
> > If MediaTek uart enabled(SERIAL_8250_MT6577), and want to improve
> > the performance, can enable the function.
> >
> > Signed-off-by: Long Cheng <long.cheng@...iatek.com>
> > ---
> > drivers/dma/mediatek/8250_mtk_dma.c | 694 +++++++++++++++++++++++++++++++++++
> > drivers/dma/mediatek/Kconfig | 11 +
> > drivers/dma/mediatek/Makefile | 1 +
> > 3 files changed, 706 insertions(+)
> > create mode 100644 drivers/dma/mediatek/8250_mtk_dma.c
> >
> > diff --git a/drivers/dma/mediatek/8250_mtk_dma.c b/drivers/dma/mediatek/8250_mtk_dma.c
> > new file mode 100644
> > index 0000000..c4090f2
> > --- /dev/null
> > +++ b/drivers/dma/mediatek/8250_mtk_dma.c
> > @@ -0,0 +1,694 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * MediaTek 8250 DMA driver.
> > + *
> > + * Copyright (c) 2018 MediaTek Inc.
> > + * Author: Long Cheng <long.cheng@...iatek.com>
> > + */
> > +
> > +#include <linux/clk.h>
> > +#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/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of_dma.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/iopoll.h>
>
> Alphabetical order.
ok, i will order.
>
> > +
> > +#include "../virt-dma.h"
> > +
> > +#define MTK_UART_APDMA_CHANNELS (CONFIG_SERIAL_8250_NR_UARTS * 2)
> > +
> > +#define VFF_EN_B BIT(0)
> > +#define VFF_STOP_B BIT(0)
> > +#define VFF_FLUSH_B BIT(0)
> > +#define VFF_4G_SUPPORT_B BIT(0)
> > +#define VFF_RX_INT_EN0_B BIT(0) /*rx valid size >= vff thre*/
> > +#define VFF_RX_INT_EN1_B BIT(1)
> > +#define VFF_TX_INT_EN_B BIT(0) /*tx left size >= vff thre*/
> > +#define VFF_WARM_RST_B BIT(0)
> > +#define VFF_RX_INT_FLAG_CLR_B (BIT(0) | BIT(1))
> > +#define VFF_TX_INT_FLAG_CLR_B 0
> > +#define VFF_STOP_CLR_B 0
> > +#define VFF_FLUSH_CLR_B 0
> > +#define VFF_INT_EN_CLR_B 0
> > +#define VFF_4G_SUPPORT_CLR_B 0
> > +
> > +/* interrupt trigger level for tx */
> > +#define VFF_TX_THRE(n) ((n) * 7 / 8)
> > +/* interrupt trigger level for rx */
> > +#define VFF_RX_THRE(n) ((n) * 3 / 4)
> > +
> > +#define MTK_UART_APDMA_RING_SIZE 0xffffU
> > +/* invert this bit when wrap ring head again*/
> > +#define MTK_UART_APDMA_RING_WRAP 0x10000U
> > +
> > +#define VFF_INT_FLAG 0x00
> > +#define VFF_INT_EN 0x04
> > +#define VFF_EN 0x08
> > +#define VFF_RST 0x0c
> > +#define VFF_STOP 0x10
> > +#define VFF_FLUSH 0x14
> > +#define VFF_ADDR 0x1c
> > +#define VFF_LEN 0x24
> > +#define VFF_THRE 0x28
> > +#define VFF_WPT 0x2c
> > +#define VFF_RPT 0x30
> > +/*TX: the buffer size HW can read. RX: the buffer size SW can read.*/
> > +#define VFF_VALID_SIZE 0x3c
> > +/*TX: the buffer size SW can write. RX: the buffer size HW can write.*/
> > +#define VFF_LEFT_SIZE 0x40
> > +#define VFF_DEBUG_STATUS 0x50
> > +#define VFF_4G_SUPPORT 0x54
> > +
> > +struct mtk_uart_apdmadev {
> > + struct dma_device ddev;
> > + struct clk *clk;
> > + bool support_33bits;
> > + unsigned int dma_irq[MTK_UART_APDMA_CHANNELS];
> > +};
> > +
> > +struct mtk_uart_apdma_desc {
> > + struct virt_dma_desc vd;
> > +
> > + unsigned int avail_len;
> > +};
> > +
> > +struct mtk_chan {
> > + struct virt_dma_chan vc;
> > + struct dma_slave_config cfg;
> > + void __iomem *base;
> > + struct mtk_uart_apdma_desc *desc;
> > +
> > + bool requested;
> > +
> > + unsigned int rx_status;
> > +};
> > +
> > +static inline struct mtk_uart_apdmadev *
> > +to_mtk_uart_apdma_dev(struct dma_device *d)
> > +{
> > + return container_of(d, struct mtk_uart_apdmadev, ddev);
> > +}
> > +
> > +static inline struct mtk_chan *to_mtk_uart_apdma_chan(struct dma_chan *c)
> > +{
> > + return container_of(c, struct mtk_chan, vc.chan);
> > +}
> > +
> > +static inline struct mtk_uart_apdma_desc *to_mtk_uart_apdma_desc
> > + (struct dma_async_tx_descriptor *t)
> > +{
> > + return container_of(t, struct mtk_uart_apdma_desc, vd.tx);
> > +}
> > +
> > +static void mtk_uart_apdma_chan_write(struct mtk_chan *c,
> > + unsigned int reg, unsigned int val)
> > +{
> > + writel(val, c->base + reg);
> > +}
> > +
> > +static unsigned int
> > +mtk_uart_apdma_chan_read(struct mtk_chan *c, unsigned int reg)
> > +{
> > + return readl(c->base + reg);
> > +}
> > +
> > +static void mtk_uart_apdma_desc_free(struct virt_dma_desc *vd)
> > +{
> > + struct dma_chan *chan = vd->tx.chan;
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > +
> > + kfree(c->desc);
> > + c->desc = NULL;
>
> Why? I'm afraid this may mask double-free.
>
i will remove it.
> > +}
> > +
> > +static void mtk_uart_apdma_start_tx(struct mtk_chan *c)
> > +{
> > + unsigned int txcount = c->desc->avail_len;
>
> Variable name is confusing... I'd rather have a boolean `transmitted`
> (or something), set to 0 here, and set to 1 in the loop (but again,
> maybe this is not necessary at all, see below).
ok, i modify the function and remove it.
>
> > + unsigned int len, send, left, wpt, wrap;
> > +
> > + if (mtk_uart_apdma_chan_read(c, VFF_LEFT_SIZE) == 0U) {
> > + mtk_uart_apdma_chan_write(c, VFF_INT_EN, VFF_TX_INT_EN_B);
>
> I'd add a "return;" here and de-indent the rest of the function (that
> should help to make it more readable).
add
>
> > + } else {
> > + len = mtk_uart_apdma_chan_read(c, VFF_LEN);
>
> You make an assumption below that len is always a power of 2. I wonder
> if we want to validate that with some BUG/WARN call.
>
> Also, I assume VFF_LEN is constant? Maybe we can read it once only in
> the probe function?
>
no, the value of VFF_LEN isn't constant.
> > +
> > + while (((left = mtk_uart_apdma_chan_read(c,
> > + VFF_LEFT_SIZE)) > 0U)
> > + && (c->desc->avail_len != 0U)) {
>
> Why do we need a while loop here? LEFT_SIZE will always be smaller
> than LEN, right? Shouldn't we load as much as we can, then let an
> interrupt happen and reload the FIFO at that stage? Or does this help
> gain a bit of extra performance?
i will remove while, use 'if' instead of.
>
> > + send = min_t(unsigned int, left, c->desc->avail_len);
> > + wpt = mtk_uart_apdma_chan_read(c, VFF_WPT);
> > + wrap = wpt & MTK_UART_APDMA_RING_WRAP ?
>
> wrap = wrp ^ MTK_UART_APDMA_RING_WRAP ?
>
wrap = wpt & MTK_UART_APDMA_RING_WRAP ?
i had test it.
> > + 0U : MTK_UART_APDMA_RING_WRAP;
> > +
> > + if ((wpt & (len - 1U)) + send < len)
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_WPT, wpt + send);
> > + else
> > + mtk_uart_apdma_chan_write(c, VFF_WPT,
> > + ((wpt + send) & (len - 1U))
> > + | wrap);
> > +
> > + c->desc->avail_len -= send;
> > + }
> > +
> > + if (txcount != c->desc->avail_len) {
>
> We know mtk_uart_apdma_chan_read(c, VFF_LEFT_SIZE) > 0 at least once,
> so this test should always be true.
>
> Unless we have c->desc->avail_len == 0, but then we won't even call
> this function... So this is always true.
>
yes. you are right. i will remove it.
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_EN, VFF_TX_INT_EN_B);
> > + if (mtk_uart_apdma_chan_read(c,
> > + VFF_FLUSH) == 0U)
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_FLUSH, VFF_FLUSH_B);
> > + }
> > + }
> > +}
> > +
> > +static void mtk_uart_apdma_start_rx(struct mtk_chan *c)
> > +{
> > + struct mtk_uart_apdma_desc *d = c->desc;
> > + unsigned int rx_len, wg, rg, count;
> > +
> > + if (mtk_uart_apdma_chan_read(c, VFF_VALID_SIZE) == 0U)
> > + return;
> > +
> > + if (d && vchan_next_desc(&c->vc)) {
> > + rx_len = mtk_uart_apdma_chan_read(c, VFF_LEN);
> > + rg = mtk_uart_apdma_chan_read(c, VFF_RPT);
> > + wg = mtk_uart_apdma_chan_read(c, VFF_WPT);
> > + count = ((rg ^ wg) & MTK_UART_APDMA_RING_WRAP) ?
> > + ((wg & MTK_UART_APDMA_RING_SIZE) +
> > + rx_len - (rg & MTK_UART_APDMA_RING_SIZE)) :
> > + ((wg & MTK_UART_APDMA_RING_SIZE) -
> > + (rg & MTK_UART_APDMA_RING_SIZE));
>
> This is hard to read, please use a if/else.
>
ok.
> > +
> > + c->rx_status = count;
> > + mtk_uart_apdma_chan_write(c, VFF_RPT, wg);
> > +
> > + list_del(&d->vd.node);
> > + vchan_cookie_complete(&d->vd);
> > + }
> > +}
> > +
> > +static irqreturn_t mtk_uart_apdma_irq_handler(int irq, void *dev_id)
> > +{
> > + struct dma_chan *chan = (struct dma_chan *)dev_id;
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + struct mtk_uart_apdma_desc *d;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&c->vc.lock, flags);
> > + switch (c->cfg.direction) {
> > + case DMA_DEV_TO_MEM:
>
> You use an if/else below in a similar case, please be consistent (IMHO
> if/else is a bit more compact, so I'd use that here).
>
sean wang had review it. the link
http://lists.infradead.org/pipermail/linux-mediatek/2018-December/016292.html
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_RX_INT_FLAG_CLR_B);
> > + mtk_uart_apdma_start_rx(c);
> > + break;
> > + case DMA_MEM_TO_DEV:
> > + d = c->desc;
> > +
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_TX_INT_FLAG_CLR_B);
> > +
> > + if (d->avail_len != 0U) {
> > + mtk_uart_apdma_start_tx(c);
> > + } else {
> > + list_del(&d->vd.node);
> > + vchan_cookie_complete(&d->vd);
> > + }
> > + break;
> > + default:
> > + break;
> > + }
> > + spin_unlock_irqrestore(&c->vc.lock, flags);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int mtk_uart_apdma_alloc_chan_resources(struct dma_chan *chan)
> > +{
> > + struct mtk_uart_apdmadev *mtkd = to_mtk_uart_apdma_dev(chan->device);
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + u32 status;
> > + int ret = -EBUSY;
> > +
> > + pm_runtime_get_sync(mtkd->ddev.dev);
> > +
> > + mtk_uart_apdma_chan_write(c, VFF_ADDR, 0);
> > + mtk_uart_apdma_chan_write(c, VFF_THRE, 0);
> > + mtk_uart_apdma_chan_write(c, VFF_LEN, 0);
> > + mtk_uart_apdma_chan_write(c, VFF_RST, VFF_WARM_RST_B);
> > +
> > + ret = readx_poll_timeout(readl,
> > + c->base + VFF_EN,
> > + status, status == 0, 10, 100);
> > + if (ret) {
> > + dev_err(c->vc.chan.device->dev,
> > + "dma reset: fail, timeout\n");
> > + goto exit;
> > + }
> > +
> > + if (!c->requested) {
> > + c->requested = true;
> > + ret = request_irq(mtkd->dma_irq[chan->chan_id],
> > + mtk_uart_apdma_irq_handler,
> > + IRQF_TRIGGER_NONE,
> > + KBUILD_MODNAME, chan);
> > + if (ret < 0) {
> > + dev_err(chan->device->dev, "Can't request dma IRQ\n");
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + if (mtkd->support_33bits)
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_4G_SUPPORT, VFF_4G_SUPPORT_CLR_B);
> > +
> > +exit:
> > + return ret;
> > +}
> > +
> > +static void mtk_uart_apdma_free_chan_resources(struct dma_chan *chan)
> > +{
> > + struct mtk_uart_apdmadev *mtkd = to_mtk_uart_apdma_dev(chan->device);
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > +
> > + if (c->requested) {
> > + c->requested = false;
> > + free_irq(mtkd->dma_irq[chan->chan_id], chan);
> > + }
> > +
> > + tasklet_kill(&c->vc.task);
> > +
> > + vchan_free_chan_resources(&c->vc);
> > +
> > + pm_runtime_put_sync(mtkd->ddev.dev);
> > +}
> > +
> > +static enum dma_status mtk_uart_apdma_tx_status(struct dma_chan *chan,
> > + dma_cookie_t cookie,
> > + struct dma_tx_state *txstate)
> > +{
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + enum dma_status ret;
> > + unsigned long flags;
> > +
> > + if (!txstate)
> > + return DMA_ERROR;
> > +
> > + ret = dma_cookie_status(chan, cookie, txstate);
> > + spin_lock_irqsave(&c->vc.lock, flags);
> > + if (ret == DMA_IN_PROGRESS) {
> > + c->rx_status = mtk_uart_apdma_chan_read(c, VFF_RPT)
> > + & MTK_UART_APDMA_RING_SIZE;
> > + dma_set_residue(txstate, c->rx_status);
> > + } else if (ret == DMA_COMPLETE && c->cfg.direction == DMA_DEV_TO_MEM) {
> > + dma_set_residue(txstate, c->rx_status);
> > + } else {
> > + dma_set_residue(txstate, 0);
> > + }
> > + spin_unlock_irqrestore(&c->vc.lock, flags);
> > +
> > + return ret;
> > +}
> > +
> > +/*
> > + * dmaengine_prep_slave_single will call the function. and sglen is 1.
> > + * 8250 uart using one ring buffer, and deal with one sg.
> > + */
> > +static struct dma_async_tx_descriptor *mtk_uart_apdma_prep_slave_sg
> > + (struct dma_chan *chan, struct scatterlist *sgl,
> > + unsigned int sglen, enum dma_transfer_direction dir,
> > + unsigned long tx_flags, void *context)
> > +{
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + struct mtk_uart_apdma_desc *d;
> > +
> > + if ((dir != DMA_DEV_TO_MEM) &&
> > + (dir != DMA_MEM_TO_DEV)) {
> > + dev_err(chan->device->dev, "bad direction\n");
> > + return NULL;
> > + }
> > +
> > + /* Now allocate and setup the descriptor */
> > + d = kzalloc(sizeof(*d), GFP_ATOMIC);
> > + if (!d)
> > + return NULL;
> > +
> > + /* sglen is 1 */
> > + d->avail_len = sg_dma_len(sgl);
> > +
> > + return vchan_tx_prep(&c->vc, &d->vd, tx_flags);
> > +}
> > +
> > +static void mtk_uart_apdma_issue_pending(struct dma_chan *chan)
> > +{
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + struct virt_dma_desc *vd;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&c->vc.lock, flags);
> > + if (c->cfg.direction == DMA_DEV_TO_MEM) {
> > + if (vchan_issue_pending(&c->vc) && !c->desc) {
> > + vd = vchan_next_desc(&c->vc);
> > + c->desc = to_mtk_uart_apdma_desc(&vd->tx);
> > + mtk_uart_apdma_start_rx(c);
> > + }
> > + } else if (c->cfg.direction == DMA_MEM_TO_DEV) {
> > + if (vchan_issue_pending(&c->vc) && !c->desc) {
> > + vd = vchan_next_desc(&c->vc);
> > + c->desc = to_mtk_uart_apdma_desc(&vd->tx);
> > + mtk_uart_apdma_start_tx(c);
> > + }
> > + }
> > + spin_unlock_irqrestore(&c->vc.lock, flags);
> > +}
> > +
> > +static int mtk_uart_apdma_slave_config(struct dma_chan *chan,
> > + struct dma_slave_config *cfg)
> > +{
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + struct mtk_uart_apdmadev *mtkd =
> > + to_mtk_uart_apdma_dev(c->vc.chan.device);
> > +
> > + c->cfg = *cfg;
> > +
> > + if (cfg->direction == DMA_DEV_TO_MEM) {
> > + unsigned int rx_len = cfg->src_addr_width * 1024;
> > +
> > + mtk_uart_apdma_chan_write(c, VFF_ADDR, cfg->src_addr);
> > + mtk_uart_apdma_chan_write(c, VFF_LEN, rx_len);
> > + mtk_uart_apdma_chan_write(c, VFF_THRE, VFF_RX_THRE(rx_len));
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_EN, VFF_RX_INT_EN0_B
> > + | VFF_RX_INT_EN1_B);
> > + mtk_uart_apdma_chan_write(c, VFF_RPT, 0);
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_RX_INT_FLAG_CLR_B);
> > + mtk_uart_apdma_chan_write(c, VFF_EN, VFF_EN_B);
> > + } else if (cfg->direction == DMA_MEM_TO_DEV) {
> > + unsigned int tx_len = cfg->dst_addr_width * 1024;
> > +
> > + mtk_uart_apdma_chan_write(c, VFF_ADDR, cfg->dst_addr);
> > + mtk_uart_apdma_chan_write(c, VFF_LEN, tx_len);
> > + mtk_uart_apdma_chan_write(c, VFF_THRE, VFF_TX_THRE(tx_len));
> > + mtk_uart_apdma_chan_write(c, VFF_WPT, 0);
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_TX_INT_FLAG_CLR_B);
> > + mtk_uart_apdma_chan_write(c, VFF_EN, VFF_EN_B);
> > + }
> > +
> > + if (mtkd->support_33bits)
> > + mtk_uart_apdma_chan_write(c, VFF_4G_SUPPORT, VFF_4G_SUPPORT_B);
> > +
> > + if (mtk_uart_apdma_chan_read(c, VFF_EN) != VFF_EN_B) {
> > + dev_err(chan->device->dev,
> > + "config dma dir[%d] fail\n", cfg->direction);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_uart_apdma_terminate_all(struct dma_chan *chan)
> > +{
> > + struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
> > + unsigned long flags;
> > + u32 status;
> > + int ret;
> > +
> > + spin_lock_irqsave(&c->vc.lock, flags);
> > +
> > + mtk_uart_apdma_chan_write(c, VFF_FLUSH, VFF_FLUSH_CLR_B);
> > + /* Wait for flush */
> > + ret = readx_poll_timeout(readl,
> > + c->base + VFF_FLUSH,
> > + status,
> > + (status & VFF_FLUSH_B) != VFF_FLUSH_B,
> > + 10, 100);
> > + if (ret)
> > + dev_err(c->vc.chan.device->dev,
> > + "dma stop: polling FLUSH fail, DEBUG=0x%x\n",
> > + mtk_uart_apdma_chan_read(c, VFF_DEBUG_STATUS));
> > +
> > + /*set stop as 1 -> wait until en is 0 -> set stop as 0*/
> > + mtk_uart_apdma_chan_write(c, VFF_STOP, VFF_STOP_B);
> > + ret = readx_poll_timeout(readl,
> > + c->base + VFF_EN,
> > + status, status == 0, 10, 100);
> > + if (ret)
> > + dev_err(c->vc.chan.device->dev,
> > + "dma stop: polling VFF_EN fail, DEBUG=0x%x\n",
> > + mtk_uart_apdma_chan_read(c, VFF_DEBUG_STATUS));
> > +
> > + mtk_uart_apdma_chan_write(c, VFF_STOP, VFF_STOP_CLR_B);
> > + mtk_uart_apdma_chan_write(c, VFF_INT_EN, VFF_INT_EN_CLR_B);
> > +
> > + switch (c->cfg.direction) {
> > + case DMA_DEV_TO_MEM:
>
> Ditto, if/else?
>
ditto.
http://lists.infradead.org/pipermail/linux-mediatek/2018-December/016292.html
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_RX_INT_FLAG_CLR_B);
> > + break;
> > + case DMA_MEM_TO_DEV:
> > + mtk_uart_apdma_chan_write(c,
> > + VFF_INT_FLAG, VFF_TX_INT_FLAG_CLR_B);
> > + break;
> > + default:
> > + break;
> > + }
> > +
> > + spin_unlock_irqrestore(&c->vc.lock, flags);
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_uart_apdma_device_pause(struct dma_chan *chan)
> > +{
> > + /* just for check caps pass */
> > + return 0;
> > +}
> > +
> > +static int mtk_uart_apdma_device_resume(struct dma_chan *chan)
> > +{
> > + /* just for check caps pass */
> > + return 0;
> > +}
> > +
> > +static void mtk_uart_apdma_free(struct mtk_uart_apdmadev *mtkd)
> > +{
> > + while (list_empty(&mtkd->ddev.channels) == 0) {
> > + struct mtk_chan *c = list_first_entry(&mtkd->ddev.channels,
> > + struct mtk_chan, vc.chan.device_node);
> > +
> > + list_del(&c->vc.chan.device_node);
> > + tasklet_kill(&c->vc.task);
> > + }
> > +}
> > +
> > +static const struct of_device_id mtk_uart_apdma_match[] = {
> > + { .compatible = "mediatek,mt6577-uart-dma", },
> > + { /* sentinel */ },
> > +};
> > +MODULE_DEVICE_TABLE(of, mtk_uart_apdma_match);
> > +
> > +static int mtk_uart_apdma_probe(struct platform_device *pdev)
> > +{
> > + struct mtk_uart_apdmadev *mtkd;
> > + struct resource *res;
> > + struct mtk_chan *c;
> > + unsigned int i;
> > + int rc;
> > +
> > + mtkd = devm_kzalloc(&pdev->dev, sizeof(*mtkd), GFP_KERNEL);
> > + if (!mtkd)
> > + return -ENOMEM;
> > +
> > + mtkd->clk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(mtkd->clk)) {
> > + dev_err(&pdev->dev, "No clock specified\n");
> > + rc = PTR_ERR(mtkd->clk);
> > + goto err_no_dma;
> > + }
> > +
> > + if (of_property_read_bool(pdev->dev.of_node, "dma-33bits")) {
> > + dev_info(&pdev->dev, "Support dma 33bits\n");
>
> Drop this, a bit verbose.
>
> > + mtkd->support_33bits = true;
> > + }
> > +
> > + rc = dma_set_mask_and_coherent(&pdev->dev,
> > + DMA_BIT_MASK(32 | mtkd->support_33bits));
> > + if (rc)
> > + goto err_no_dma;
> > +
> > + dma_cap_set(DMA_SLAVE, mtkd->ddev.cap_mask);
> > + mtkd->ddev.device_alloc_chan_resources =
> > + mtk_uart_apdma_alloc_chan_resources;
> > + mtkd->ddev.device_free_chan_resources =
> > + mtk_uart_apdma_free_chan_resources;
> > + mtkd->ddev.device_tx_status = mtk_uart_apdma_tx_status;
> > + mtkd->ddev.device_issue_pending = mtk_uart_apdma_issue_pending;
> > + mtkd->ddev.device_prep_slave_sg = mtk_uart_apdma_prep_slave_sg;
> > + mtkd->ddev.device_config = mtk_uart_apdma_slave_config;
> > + mtkd->ddev.device_pause = mtk_uart_apdma_device_pause;
> > + mtkd->ddev.device_resume = mtk_uart_apdma_device_resume;
> > + mtkd->ddev.device_terminate_all = mtk_uart_apdma_terminate_all;
> > + mtkd->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE);
> > + mtkd->ddev.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE);
> > + mtkd->ddev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
> > + mtkd->ddev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
> > + mtkd->ddev.dev = &pdev->dev;
> > + INIT_LIST_HEAD(&mtkd->ddev.channels);
> > +
> > + for (i = 0; i < MTK_UART_APDMA_CHANNELS; i++) {
> > + c = devm_kzalloc(mtkd->ddev.dev, sizeof(*c), GFP_KERNEL);
> > + if (!c) {
> > + rc = -ENODEV;
> > + goto err_no_dma;
> > + }
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, i);
> > + if (!res) {
> > + rc = -ENODEV;
> > + goto err_no_dma;
> > + }
> > +
> > + c->base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(c->base)) {
> > + rc = PTR_ERR(c->base);
> > + goto err_no_dma;
> > + }
> > + c->requested = false;
> > + c->vc.desc_free = mtk_uart_apdma_desc_free;
> > + vchan_init(&c->vc, &mtkd->ddev);
> > +
> > + mtkd->dma_irq[i] = platform_get_irq(pdev, i);
> > + if ((int)mtkd->dma_irq[i] < 0) {
> > + dev_err(&pdev->dev, "failed to get IRQ[%d]\n", i);
> > + rc = -EINVAL;
> > + goto err_no_dma;
> > + }
> > + }
> > +
> > + pm_runtime_enable(&pdev->dev);
> > + pm_runtime_set_active(&pdev->dev);
> > +
> > + rc = dma_async_device_register(&mtkd->ddev);
> > + if (rc)
> > + goto rpm_disable;
> > +
> > + platform_set_drvdata(pdev, mtkd);
> > +
> > + if (pdev->dev.of_node) {
> > + /* Device-tree DMA controller registration */
> > + rc = of_dma_controller_register(pdev->dev.of_node,
> > + of_dma_xlate_by_chan_id,
> > + mtkd);
> > + if (rc)
> > + goto dma_remove;
> > + }
> > +
> > + return rc;
> > +
> > +dma_remove:
> > + dma_async_device_unregister(&mtkd->ddev);
> > +rpm_disable:
> > + pm_runtime_disable(&pdev->dev);
> > +err_no_dma:
> > + mtk_uart_apdma_free(mtkd);
> > + return rc;
> > +}
> > +
> > +static int mtk_uart_apdma_remove(struct platform_device *pdev)
> > +{
> > + struct mtk_uart_apdmadev *mtkd = platform_get_drvdata(pdev);
> > +
> > + if (pdev->dev.of_node)
> > + of_dma_controller_free(pdev->dev.of_node);
> > +
> > + pm_runtime_disable(&pdev->dev);
> > + pm_runtime_put_noidle(&pdev->dev);
> > +
> > + dma_async_device_unregister(&mtkd->ddev);
> > + mtk_uart_apdma_free(mtkd);
> > +
> > + return 0;
> > +}
> > +
> > +#ifdef CONFIG_PM_SLEEP
> > +static int mtk_uart_apdma_suspend(struct device *dev)
> > +{
> > + struct mtk_uart_apdmadev *mtkd = dev_get_drvdata(dev);
> > +
> > + if (!pm_runtime_suspended(dev))
> > + clk_disable_unprepare(mtkd->clk);
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_uart_apdma_resume(struct device *dev)
> > +{
> > + int ret;
> > + struct mtk_uart_apdmadev *mtkd = dev_get_drvdata(dev);
> > +
> > + if (!pm_runtime_suspended(dev)) {
> > + ret = clk_prepare_enable(mtkd->clk);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +#endif /* CONFIG_PM_SLEEP */
> > +
> > +#ifdef CONFIG_PM
> > +static int mtk_uart_apdma_runtime_suspend(struct device *dev)
> > +{
> > + struct mtk_uart_apdmadev *mtkd = dev_get_drvdata(dev);
> > +
> > + clk_disable_unprepare(mtkd->clk);
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_uart_apdma_runtime_resume(struct device *dev)
> > +{
> > + int ret;
> > + struct mtk_uart_apdmadev *mtkd = dev_get_drvdata(dev);
> > +
> > + ret = clk_prepare_enable(mtkd->clk);
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +#endif /* CONFIG_PM */
> > +
> > +static const struct dev_pm_ops mtk_uart_apdma_pm_ops = {
> > + SET_SYSTEM_SLEEP_PM_OPS(mtk_uart_apdma_suspend, mtk_uart_apdma_resume)
> > + SET_RUNTIME_PM_OPS(mtk_uart_apdma_runtime_suspend,
> > + mtk_uart_apdma_runtime_resume, NULL)
> > +};
> > +
> > +static struct platform_driver mtk_uart_apdma_driver = {
> > + .probe = mtk_uart_apdma_probe,
> > + .remove = mtk_uart_apdma_remove,
> > + .driver = {
> > + .name = KBUILD_MODNAME,
> > + .pm = &mtk_uart_apdma_pm_ops,
> > + .of_match_table = of_match_ptr(mtk_uart_apdma_match),
> > + },
> > +};
> > +
> > +module_platform_driver(mtk_uart_apdma_driver);
> > +
> > +MODULE_DESCRIPTION("MediaTek UART APDMA Controller Driver");
> > +MODULE_AUTHOR("Long Cheng <long.cheng@...iatek.com>");
> > +MODULE_LICENSE("GPL v2");
> > +
> > diff --git a/drivers/dma/mediatek/Kconfig b/drivers/dma/mediatek/Kconfig
> > index 27bac0b..1a523c87 100644
> > --- a/drivers/dma/mediatek/Kconfig
> > +++ b/drivers/dma/mediatek/Kconfig
> > @@ -1,4 +1,15 @@
> >
> > +config DMA_MTK_UART
> > + tristate "MediaTek SoCs APDMA support for UART"
> > + depends on OF && SERIAL_8250_MT6577
> > + select DMA_ENGINE
> > + select DMA_VIRTUAL_CHANNELS
> > + help
> > + Support for the UART DMA engine found on MediaTek MTK SoCs.
> > + when SERIAL_8250_MT6577 is enabled, and if you want to use DMA,
> > + you can enable the config. the DMA engine can only be used
> > + with MediaTek SoCs.
> > +
> > config MTK_HSDMA
> > tristate "MediaTek High-Speed DMA controller support"
> > depends on ARCH_MEDIATEK || COMPILE_TEST
> > diff --git a/drivers/dma/mediatek/Makefile b/drivers/dma/mediatek/Makefile
> > index 6e778f8..2f2efd9 100644
> > --- a/drivers/dma/mediatek/Makefile
> > +++ b/drivers/dma/mediatek/Makefile
> > @@ -1 +1,2 @@
> > +obj-$(CONFIG_DMA_MTK_UART) += 8250_mtk_dma.o
> > obj-$(CONFIG_MTK_HSDMA) += mtk-hsdma.o
> > --
> > 1.7.9.5
> >
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