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ARM: PL011: Fix DMA support 

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: cb06ff102e ("ARM: PL011: Add support for Rx DMA buffer polling.")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Gregory 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Arnd Bergmann 2023-11-22 18:15:03 +01:00 committed by Greg Kroah-Hartman
parent 08ce9a1b72
commit 58ac1b3799
1 changed files with 54 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
drivers/tty/serial/amba-pl011.c
View File

@ -218,17 +218,18 @@ static struct vendor_data vendor_st = {
/* Deals with DMA transactions */
struct pl011_sgbuf {
struct scatterlist sg;
char *buf;
struct pl011_dmabuf {
dma_addr_t dma;
size_t len;
char *buf;
};
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;
@ -241,7 +242,8 @@ 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;
};
@ -366,32 +368,24 @@ 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);
}
}
@ -552,8 +546,8 @@ static void pl011_dma_tx_callback(void *data)
uart_port_lock_irqsave(&uap->port, &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;
@ -639,18 +633,19 @@ 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
@ -813,8 +808,8 @@ __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);
@ -828,15 +823,15 @@ 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);
/*
@ -876,8 +871,8 @@ 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() */
@ -886,7 +881,7 @@ 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;
@ -900,7 +895,7 @@ 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;
@ -911,7 +906,7 @@ 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
@ -946,8 +941,8 @@ 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;
@ -969,7 +964,7 @@ 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);
@ -996,8 +991,8 @@ 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;
@ -1015,7 +1010,7 @@ 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);
@ -1067,16 +1062,16 @@ static void pl011_dma_rx_poll(struct timer_list *t)
unsigned long flags;
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;
@ -1123,7 +1118,7 @@ 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;
@ -1133,7 +1128,7 @@ 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",
@ -1141,12 +1136,12 @@ 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;
}
@ -1200,8 +1195,9 @@ 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_TO_DEVICE);
dma_unmap_single(uap->dmatx.chan->device->dev,
uap->dmatx.dma, uap->dmatx.len,
DMA_TO_DEVICE);
uap->dmatx.queued = false;
}
@ -1212,8 +1208,8 @@ 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;