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| author | Miquel Raynal <miquel.raynal@bootlin.com> | 2022-04-22 20:06:11 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-26 13:25:47 +0200 |
| commit | e4fb03fe10c5e7a5d9aef7cefe815253274fb9ee (patch) | |
| tree | 84fdb9844dd6f5a942190ca254d4ce143dc8ba96 /drivers/tty | |
| parent | 593dea000bc1f160623f8cf65ad5e47c72f4ec67 (diff) | |
| download | linux-e4fb03fe10c5e7a5d9aef7cefe815253274fb9ee.tar.gz linux-e4fb03fe10c5e7a5d9aef7cefe815253274fb9ee.tar.bz2 linux-e4fb03fe10c5e7a5d9aef7cefe815253274fb9ee.zip | |
serial: 8250: dma: Allow driver operations before starting DMA transfers
One situation where this could be used is when configuring the UART
controller to be the DMA flow controller. This is a typical case where
the driver might need to program a few more registers before starting a
DMA transfer. Provide the necessary infrastructure to support this
case.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20220422180615.9098-6-miquel.raynal@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250.h | 18 | ||||
| -rw-r--r-- | drivers/tty/serial/8250/8250_dma.c | 4 |
2 files changed, 22 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 39ffeb37786f..5a4e05c0e552 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -17,6 +17,8 @@ struct uart_8250_dma { int (*tx_dma)(struct uart_8250_port *p); int (*rx_dma)(struct uart_8250_port *p); + void (*prepare_tx_dma)(struct uart_8250_port *p); + void (*prepare_rx_dma)(struct uart_8250_port *p); /* Filter function */ dma_filter_fn fn; @@ -302,6 +304,22 @@ extern int serial8250_rx_dma(struct uart_8250_port *); extern void serial8250_rx_dma_flush(struct uart_8250_port *); extern int serial8250_request_dma(struct uart_8250_port *); extern void serial8250_release_dma(struct uart_8250_port *); + +static inline void serial8250_do_prepare_tx_dma(struct uart_8250_port *p) +{ + struct uart_8250_dma *dma = p->dma; + + if (dma->prepare_tx_dma) + dma->prepare_tx_dma(p); +} + +static inline void serial8250_do_prepare_rx_dma(struct uart_8250_port *p) +{ + struct uart_8250_dma *dma = p->dma; + + if (dma->prepare_rx_dma) + dma->prepare_rx_dma(p); +} #else static inline int serial8250_tx_dma(struct uart_8250_port *p) { diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index b3c3f7e5851a..1bdc8d6432fe 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -86,6 +86,8 @@ int serial8250_tx_dma(struct uart_8250_port *p) dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); + serial8250_do_prepare_tx_dma(p); + desc = dmaengine_prep_slave_single(dma->txchan, dma->tx_addr + xmit->tail, dma->tx_size, DMA_MEM_TO_DEV, @@ -123,6 +125,8 @@ int serial8250_rx_dma(struct uart_8250_port *p) if (dma->rx_running) return 0; + serial8250_do_prepare_rx_dma(p); + desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, dma->rx_size, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); |