Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d896c47f authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
Browse files

ARM: PL011: Fix DMA support 

commit 58ac1b3799799069d53f5bf95c093f2fe8dd3cc5 upstream.

Since there is no guarantee that the memory returned by
dma_alloc_coherent() is associated with a 'struct page', using the
architecture specific phys_to_page() is wrong, but using
virt_to_page() would be as well.

Stop using sg lists altogether and just use the *_single() functions
instead. This also simplifies the code a bit since the scatterlists in
this driver always have only one entry anyway.

https://lore.kernel.org/lkml/86db0fe5-930d-4cbb-bd7d-03367da38951@app.fastmail.com/
    Use consistent names for dma buffers

gc: Add a commit log from the initial thread:
https://lore.kernel.org/lkml/86db0fe5-930d-4cbb-bd7d-03367da38951@app.fastmail.com/


    Use consistent names for dma buffers

Fixes: cb06ff10 ("ARM: PL011: Add support for Rx DMA buffer polling.")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Tested-by: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20231122171503.235649-1-gregory.clement@bootlin.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 880b035b

drivers/tty/serial/amba-pl011.c

+54 −58
Original line number Diff line number Diff line
@@ -227,8 +227,9 @@ static struct vendor_data vendor_zte = { 


/* Deals with DMA transactions */



struct pl011_sgbuf {

	struct scatterlist sg;

struct pl011_dmabuf {

	dma_addr_t		dma;

	size_t			len;

	char			*buf;

};
@@ -236,8 +237,8 @@ struct pl011_dmarx_data { 
	struct dma_chan		*chan;

	struct completion	complete;

	bool			use_buf_b;

	struct pl011_sgbuf	sgbuf_a;

	struct pl011_sgbuf	sgbuf_b;

	struct pl011_dmabuf	dbuf_a;

	struct pl011_dmabuf	dbuf_b;

	dma_cookie_t		cookie;

	bool			running;

	struct timer_list	timer;
@@ -250,7 +251,8 @@ struct pl011_dmarx_data { 


struct pl011_dmatx_data {

	struct dma_chan		*chan;

	struct scatterlist	sg;

	dma_addr_t		dma;

	size_t			len;

	char			*buf;

	bool			queued;

};
@@ -371,32 +373,24 @@ static int pl011_fifo_to_tty(struct uart_amba_port *uap) 


#define PL011_DMA_BUFFER_SIZE PAGE_SIZE



static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg,

static int pl011_dmabuf_init(struct dma_chan *chan, struct pl011_dmabuf *db,

	enum dma_data_direction dir)

{

	dma_addr_t dma_addr;



	sg->buf = dma_alloc_coherent(chan->device->dev,

		PL011_DMA_BUFFER_SIZE, &dma_addr, GFP_KERNEL);

	if (!sg->buf)

	db->buf = dma_alloc_coherent(chan->device->dev, PL011_DMA_BUFFER_SIZE,

				     &db->dma, GFP_KERNEL);

	if (!db->buf)

		return -ENOMEM;



	sg_init_table(&sg->sg, 1);

	sg_set_page(&sg->sg, phys_to_page(dma_addr),

		PL011_DMA_BUFFER_SIZE, offset_in_page(dma_addr));

	sg_dma_address(&sg->sg) = dma_addr;

	sg_dma_len(&sg->sg) = PL011_DMA_BUFFER_SIZE;

	db->len = PL011_DMA_BUFFER_SIZE;



	return 0;

}



static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg,

static void pl011_dmabuf_free(struct dma_chan *chan, struct pl011_dmabuf *db,

	enum dma_data_direction dir)

{

	if (sg->buf) {

	if (db->buf) {

		dma_free_coherent(chan->device->dev,

			PL011_DMA_BUFFER_SIZE, sg->buf,

			sg_dma_address(&sg->sg));

				  PL011_DMA_BUFFER_SIZE, db->buf, db->dma);

	}

}
@@ -557,8 +551,8 @@ static void pl011_dma_tx_callback(void *data) 


	spin_lock_irqsave(&uap->port.lock, flags);

	if (uap->dmatx.queued)

		dma_unmap_sg(dmatx->chan->device->dev, &dmatx->sg, 1,

			     DMA_TO_DEVICE);

		dma_unmap_single(dmatx->chan->device->dev, dmatx->dma,

				dmatx->len, DMA_TO_DEVICE);



	dmacr = uap->dmacr;

	uap->dmacr = dmacr & ~UART011_TXDMAE;
@@ -644,18 +638,19 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap) 
			memcpy(&dmatx->buf[first], &xmit->buf[0], second);

	}



	dmatx->sg.length = count;



	if (dma_map_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE) != 1) {

	dmatx->len = count;

	dmatx->dma = dma_map_single(dma_dev->dev, dmatx->buf, count,

				    DMA_TO_DEVICE);

	if (dmatx->dma == DMA_MAPPING_ERROR) {

		uap->dmatx.queued = false;

		dev_dbg(uap->port.dev, "unable to map TX DMA\n");

		return -EBUSY;

	}



	desc = dmaengine_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV,

	desc = dmaengine_prep_slave_single(chan, dmatx->dma, dmatx->len, DMA_MEM_TO_DEV,

					     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

	if (!desc) {

		dma_unmap_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE);

		dma_unmap_single(dma_dev->dev, dmatx->dma, dmatx->len, DMA_TO_DEVICE);

		uap->dmatx.queued = false;

		/*

		 * If DMA cannot be used right now, we complete this
@@ -819,8 +814,8 @@ __acquires(&uap->port.lock) 
	dmaengine_terminate_async(uap->dmatx.chan);



	if (uap->dmatx.queued) {

		dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,

			     DMA_TO_DEVICE);

		dma_unmap_single(uap->dmatx.chan->device->dev, uap->dmatx.dma,

				 uap->dmatx.len, DMA_TO_DEVICE);

		uap->dmatx.queued = false;

		uap->dmacr &= ~UART011_TXDMAE;

		pl011_write(uap->dmacr, uap, REG_DMACR);
@@ -834,15 +829,15 @@ static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap) 
	struct dma_chan *rxchan = uap->dmarx.chan;

	struct pl011_dmarx_data *dmarx = &uap->dmarx;

	struct dma_async_tx_descriptor *desc;

	struct pl011_sgbuf *sgbuf;

	struct pl011_dmabuf *dbuf;



	if (!rxchan)

		return -EIO;



	/* Start the RX DMA job */

	sgbuf = uap->dmarx.use_buf_b ?

		&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;

	desc = dmaengine_prep_slave_sg(rxchan, &sgbuf->sg, 1,

	dbuf = uap->dmarx.use_buf_b ?

		&uap->dmarx.dbuf_b : &uap->dmarx.dbuf_a;

	desc = dmaengine_prep_slave_single(rxchan, dbuf->dma, dbuf->len,

					DMA_DEV_TO_MEM,

					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

	/*
@@ -882,8 +877,8 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, 
			       bool readfifo)

{

	struct tty_port *port = &uap->port.state->port;

	struct pl011_sgbuf *sgbuf = use_buf_b ?

		&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;

	struct pl011_dmabuf *dbuf = use_buf_b ?

		&uap->dmarx.dbuf_b : &uap->dmarx.dbuf_a;

	int dma_count = 0;

	u32 fifotaken = 0; /* only used for vdbg() */
@@ -892,7 +887,7 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, 


	if (uap->dmarx.poll_rate) {

		/* The data can be taken by polling */

		dmataken = sgbuf->sg.length - dmarx->last_residue;

		dmataken = dbuf->len - dmarx->last_residue;

		/* Recalculate the pending size */

		if (pending >= dmataken)

			pending -= dmataken;
@@ -906,7 +901,7 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, 
		 * Note that tty_insert_flip_buf() tries to take as many chars

		 * as it can.

		 */

		dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,

		dma_count = tty_insert_flip_string(port, dbuf->buf + dmataken,

				pending);



		uap->port.icount.rx += dma_count;
@@ -917,7 +912,7 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, 


	/* Reset the last_residue for Rx DMA poll */

	if (uap->dmarx.poll_rate)

		dmarx->last_residue = sgbuf->sg.length;

		dmarx->last_residue = dbuf->len;



	/*

	 * Only continue with trying to read the FIFO if all DMA chars have
@@ -954,8 +949,8 @@ static void pl011_dma_rx_irq(struct uart_amba_port *uap) 
{

	struct pl011_dmarx_data *dmarx = &uap->dmarx;

	struct dma_chan *rxchan = dmarx->chan;

	struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?

		&dmarx->sgbuf_b : &dmarx->sgbuf_a;

	struct pl011_dmabuf *dbuf = dmarx->use_buf_b ?

		&dmarx->dbuf_b : &dmarx->dbuf_a;

	size_t pending;

	struct dma_tx_state state;

	enum dma_status dmastat;
@@ -977,7 +972,7 @@ static void pl011_dma_rx_irq(struct uart_amba_port *uap) 
	pl011_write(uap->dmacr, uap, REG_DMACR);

	uap->dmarx.running = false;



	pending = sgbuf->sg.length - state.residue;

	pending = dbuf->len - state.residue;

	BUG_ON(pending > PL011_DMA_BUFFER_SIZE);

	/* Then we terminate the transfer - we now know our residue */

	dmaengine_terminate_all(rxchan);
@@ -1004,8 +999,8 @@ static void pl011_dma_rx_callback(void *data) 
	struct pl011_dmarx_data *dmarx = &uap->dmarx;

	struct dma_chan *rxchan = dmarx->chan;

	bool lastbuf = dmarx->use_buf_b;

	struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?

		&dmarx->sgbuf_b : &dmarx->sgbuf_a;

	struct pl011_dmabuf *dbuf = dmarx->use_buf_b ?

		&dmarx->dbuf_b : &dmarx->dbuf_a;

	size_t pending;

	struct dma_tx_state state;

	int ret;
@@ -1023,7 +1018,7 @@ static void pl011_dma_rx_callback(void *data) 
	 * the DMA irq handler. So we check the residue here.

	 */

	rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);

	pending = sgbuf->sg.length - state.residue;

	pending = dbuf->len - state.residue;

	BUG_ON(pending > PL011_DMA_BUFFER_SIZE);

	/* Then we terminate the transfer - we now know our residue */

	dmaengine_terminate_all(rxchan);
@@ -1075,16 +1070,16 @@ static void pl011_dma_rx_poll(struct timer_list *t) 
	unsigned long flags = 0;

	unsigned int dmataken = 0;

	unsigned int size = 0;

	struct pl011_sgbuf *sgbuf;

	struct pl011_dmabuf *dbuf;

	int dma_count;

	struct dma_tx_state state;



	sgbuf = dmarx->use_buf_b ? &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;

	dbuf = dmarx->use_buf_b ? &uap->dmarx.dbuf_b : &uap->dmarx.dbuf_a;

	rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);

	if (likely(state.residue < dmarx->last_residue)) {

		dmataken = sgbuf->sg.length - dmarx->last_residue;

		dmataken = dbuf->len - dmarx->last_residue;

		size = dmarx->last_residue - state.residue;

		dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,

		dma_count = tty_insert_flip_string(port, dbuf->buf + dmataken,

				size);

		if (dma_count == size)

			dmarx->last_residue =  state.residue;
@@ -1131,7 +1126,7 @@ static void pl011_dma_startup(struct uart_amba_port *uap) 
		return;

	}



	sg_init_one(&uap->dmatx.sg, uap->dmatx.buf, PL011_DMA_BUFFER_SIZE);

	uap->dmatx.len = PL011_DMA_BUFFER_SIZE;



	/* The DMA buffer is now the FIFO the TTY subsystem can use */

	uap->port.fifosize = PL011_DMA_BUFFER_SIZE;
@@ -1141,7 +1136,7 @@ static void pl011_dma_startup(struct uart_amba_port *uap) 
		goto skip_rx;



	/* Allocate and map DMA RX buffers */

	ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_a,

	ret = pl011_dmabuf_init(uap->dmarx.chan, &uap->dmarx.dbuf_a,

			       DMA_FROM_DEVICE);

	if (ret) {

		dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
@@ -1149,12 +1144,12 @@ static void pl011_dma_startup(struct uart_amba_port *uap) 
		goto skip_rx;

	}



	ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_b,

	ret = pl011_dmabuf_init(uap->dmarx.chan, &uap->dmarx.dbuf_b,

			       DMA_FROM_DEVICE);

	if (ret) {

		dev_err(uap->port.dev, "failed to init DMA %s: %d\n",

			"RX buffer B", ret);

		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a,

		pl011_dmabuf_free(uap->dmarx.chan, &uap->dmarx.dbuf_a,

				 DMA_FROM_DEVICE);

		goto skip_rx;

	}
@@ -1208,7 +1203,8 @@ static void pl011_dma_shutdown(struct uart_amba_port *uap) 
		/* In theory, this should already be done by pl011_dma_flush_buffer */

		dmaengine_terminate_all(uap->dmatx.chan);

		if (uap->dmatx.queued) {

			dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,

			dma_unmap_single(uap->dmatx.chan->device->dev,

					 uap->dmatx.dma, uap->dmatx.len,

					 DMA_TO_DEVICE);

			uap->dmatx.queued = false;

		}
@@ -1220,8 +1216,8 @@ static void pl011_dma_shutdown(struct uart_amba_port *uap) 
	if (uap->using_rx_dma) {

		dmaengine_terminate_all(uap->dmarx.chan);

		/* Clean up the RX DMA */

		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a, DMA_FROM_DEVICE);

		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_b, DMA_FROM_DEVICE);

		pl011_dmabuf_free(uap->dmarx.chan, &uap->dmarx.dbuf_a, DMA_FROM_DEVICE);

		pl011_dmabuf_free(uap->dmarx.chan, &uap->dmarx.dbuf_b, DMA_FROM_DEVICE);

		if (uap->dmarx.poll_rate)

			del_timer_sync(&uap->dmarx.timer);

		uap->using_rx_dma = false;