[RFT 00/15] tty: serial: switch from circ_buf to kfifo

[RFT 00/15] tty: serial: switch from circ_buf to kfifo

[Jiri Slaby (SUSE)]

This series switches tty serial layer to use kfifo instead of circ_buf.
Excerpt from the switching patch:
"""
Switch from struct circ_buf to proper kfifo. kfifo provides much better
API, esp. when wrap-around of the buffer needs to be taken into account.
Look at pl011_dma_tx_refill() or cpm_uart_tx_pump() changes for example.

Kfifo API can also fill in scatter-gather DMA structures, so it easier
for that use case too. Look at lpuart_dma_tx() for example. Note that
not all drivers can be converted to that (like atmel_serial), they
handle DMA specially.

Note that usb-serial uses kfifo for TX for ages.
"""

This is Request for Testing as I cannot test all the changes
(obviously). So please test your HW's serial properly.

And of course comments welcome.

I will send this as PATCHes later, when -rc1 is out, at earliest.

Cc: Al Cooper <alcooperx@gmail.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Hammer Hsieh <hammerh0314@gmail.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arm-msm@vger.kernel.org
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <michal.simek@amd.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: "Pali Rohár" <pali@kernel.org>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Taichi Sugaya <sugaya.taichi@socionext.com>
Cc: Takao Orito <orito.takao@socionext.com>
Cc: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Timur Tabi <timur@kernel.org>
Cc: Vineet Gupta <vgupta@kernel.org>

Jiri Slaby (SUSE) (15):
  kfifo: drop __kfifo_dma_out_finish_r()
  kfifo: introduce and use kfifo_skip_count()
  kfifo: add kfifo_out_linear{,_ptr}()
  kfifo: remove support for physically non-contiguous memory
  kfifo: rename l to len_to_end in setup_sgl()
  kfifo: pass offset to setup_sgl_buf() instead of a pointer
  kfifo: add kfifo_dma_out_prepare_mapped()
  kfifo: fix typos in kernel-doc
  tty: 8250_dma: use dmaengine_prep_slave_sg()
  tty: 8250_omap: use dmaengine_prep_slave_sg()
  tty: msm_serial: use dmaengine_prep_slave_sg()
  tty: serial: switch from circ_buf to kfifo
  tty: atmel_serial: use single DMA mapping for TX
  tty: atmel_serial: define macro for RX size
  tty: atmel_serial: use single DMA mapping for RX

 drivers/tty/serial/8250/8250_bcm7271.c  |  14 +--
 drivers/tty/serial/8250/8250_core.c     |   3 +-
 drivers/tty/serial/8250/8250_dma.c      |  31 +++--
 drivers/tty/serial/8250/8250_exar.c     |   5 +-
 drivers/tty/serial/8250/8250_mtk.c      |   2 +-
 drivers/tty/serial/8250/8250_omap.c     |  48 +++++---
 drivers/tty/serial/8250/8250_pci1xxxx.c |  50 ++++----
 drivers/tty/serial/8250/8250_port.c     |  22 ++--
 drivers/tty/serial/amba-pl011.c         |  46 +++-----
 drivers/tty/serial/ar933x_uart.c        |  15 ++-
 drivers/tty/serial/arc_uart.c           |   8 +-
 drivers/tty/serial/atmel_serial.c       | 150 +++++++++++-------------
 drivers/tty/serial/clps711x.c           |  12 +-
 drivers/tty/serial/cpm_uart.c           |  20 ++--
 drivers/tty/serial/digicolor-usart.c    |  12 +-
 drivers/tty/serial/dz.c                 |  13 +-
 drivers/tty/serial/fsl_linflexuart.c    |  17 +--
 drivers/tty/serial/fsl_lpuart.c         |  39 +++---
 drivers/tty/serial/icom.c               |  25 +---
 drivers/tty/serial/imx.c                |  54 ++++-----
 drivers/tty/serial/ip22zilog.c          |  26 ++--
 drivers/tty/serial/jsm/jsm_cls.c        |  29 ++---
 drivers/tty/serial/jsm/jsm_neo.c        |  38 ++----
 drivers/tty/serial/max3100.c            |  14 +--
 drivers/tty/serial/max310x.c            |  35 +++---
 drivers/tty/serial/men_z135_uart.c      |  26 ++--
 drivers/tty/serial/meson_uart.c         |  11 +-
 drivers/tty/serial/milbeaut_usio.c      |  15 +--
 drivers/tty/serial/msm_serial.c         | 114 +++++++++---------
 drivers/tty/serial/mvebu-uart.c         |   8 +-
 drivers/tty/serial/mxs-auart.c          |  23 +---
 drivers/tty/serial/pch_uart.c           |  21 ++--
 drivers/tty/serial/pic32_uart.c         |  15 ++-
 drivers/tty/serial/pmac_zilog.c         |  24 ++--
 drivers/tty/serial/qcom_geni_serial.c   |  36 +++---
 drivers/tty/serial/rda-uart.c           |  17 +--
 drivers/tty/serial/samsung_tty.c        |  54 +++++----
 drivers/tty/serial/sb1250-duart.c       |  13 +-
 drivers/tty/serial/sc16is7xx.c          |  40 +++----
 drivers/tty/serial/sccnxp.c             |  16 ++-
 drivers/tty/serial/serial-tegra.c       |  43 ++++---
 drivers/tty/serial/serial_core.c        |  56 ++++-----
 drivers/tty/serial/serial_port.c        |   2 +-
 drivers/tty/serial/sh-sci.c             |  51 ++++----
 drivers/tty/serial/sprd_serial.c        |  20 ++--
 drivers/tty/serial/st-asc.c             |   4 +-
 drivers/tty/serial/stm32-usart.c        |  52 ++++----
 drivers/tty/serial/sunhv.c              |  35 +++---
 drivers/tty/serial/sunplus-uart.c       |  16 +--
 drivers/tty/serial/sunsab.c             |  30 ++---
 drivers/tty/serial/sunsu.c              |  15 +--
 drivers/tty/serial/sunzilog.c           |  27 ++---
 drivers/tty/serial/tegra-tcu.c          |  10 +-
 drivers/tty/serial/timbuart.c           |  17 ++-
 drivers/tty/serial/uartlite.c           |  13 +-
 drivers/tty/serial/ucc_uart.c           |  20 ++--
 drivers/tty/serial/xilinx_uartps.c      |  20 ++--
 drivers/tty/serial/zs.c                 |  13 +-
 include/linux/kfifo.h                   | 143 ++++++++++++++++------
 include/linux/serial_core.h             |  49 +++++---
 lib/kfifo.c                             | 107 +++++++++--------
 61 files changed, 944 insertions(+), 960 deletions(-)

-- 
2.44.0

[RFT 11/15] tty: msm_serial: use dmaengine_prep_slave_sg()

[Jiri Slaby (SUSE)]

This is a preparatory for the serial-to-kfifo switch. kfifo understands
only scatter-gatter approach, so switch to that.

No functional change intended, it's just dmaengine_prep_slave_single()
inline expanded.

And in this case, switch from dma_map_single() to dma_map_sg() too. This
needs struct msm_dma changes. I split the rx and tx parts into an union.
TX is now struct scatterlist, RX remains the old good phys-virt-count
triple.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
---
 drivers/tty/serial/msm_serial.c | 86 +++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 37 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index d27c4c8c84e1..7bf30e632313 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -161,11 +161,16 @@ enum {
 struct msm_dma {
 	struct dma_chan		*chan;
 	enum dma_data_direction dir;
-	dma_addr_t		phys;
-	unsigned char		*virt;
+	union {
+		struct {
+			dma_addr_t		phys;
+			unsigned char		*virt;
+			unsigned int		count;
+		} rx;
+		struct scatterlist tx_sg;
+	};
 	dma_cookie_t		cookie;
 	u32			enable_bit;
-	unsigned int		count;
 	struct dma_async_tx_descriptor	*desc;
 };
 
@@ -249,8 +254,12 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
 	unsigned int mapped;
 	u32 val;
 
-	mapped = dma->count;
-	dma->count = 0;
+	if (dma->dir == DMA_TO_DEVICE) {
+		mapped = sg_dma_len(&dma->tx_sg);
+	} else {
+		mapped = dma->rx.count;
+		dma->rx.count = 0;
+	}
 
 	dmaengine_terminate_all(dma->chan);
 
@@ -265,8 +274,13 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
 	val &= ~dma->enable_bit;
 	msm_write(port, val, UARTDM_DMEN);
 
-	if (mapped)
-		dma_unmap_single(dev, dma->phys, mapped, dma->dir);
+	if (mapped) {
+		if (dma->dir == DMA_TO_DEVICE) {
+			dma_unmap_sg(dev, &dma->tx_sg, 1, dma->dir);
+			sg_init_table(&dma->tx_sg, 1);
+		} else
+			dma_unmap_single(dev, dma->rx.phys, mapped, dma->dir);
+	}
 }
 
 static void msm_release_dma(struct msm_port *msm_port)
@@ -285,7 +299,7 @@ static void msm_release_dma(struct msm_port *msm_port)
 	if (dma->chan) {
 		msm_stop_dma(&msm_port->uart, dma);
 		dma_release_channel(dma->chan);
-		kfree(dma->virt);
+		kfree(dma->rx.virt);
 	}
 
 	memset(dma, 0, sizeof(*dma));
@@ -357,8 +371,8 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
 
 	of_property_read_u32(dev->of_node, "qcom,rx-crci", &crci);
 
-	dma->virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
-	if (!dma->virt)
+	dma->rx.virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
+	if (!dma->rx.virt)
 		goto rel_rx;
 
 	memset(&conf, 0, sizeof(conf));
@@ -385,7 +399,7 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
 
 	return;
 err:
-	kfree(dma->virt);
+	kfree(dma->rx.virt);
 rel_rx:
 	dma_release_channel(dma->chan);
 no_rx:
@@ -420,7 +434,7 @@ static void msm_start_tx(struct uart_port *port)
 	struct msm_dma *dma = &msm_port->tx_dma;
 
 	/* Already started in DMA mode */
-	if (dma->count)
+	if (sg_dma_len(&dma->tx_sg))
 		return;
 
 	msm_port->imr |= MSM_UART_IMR_TXLEV;
@@ -448,12 +462,12 @@ static void msm_complete_tx_dma(void *args)
 	uart_port_lock_irqsave(port, &flags);
 
 	/* Already stopped */
-	if (!dma->count)
+	if (!sg_dma_len(&dma->tx_sg))
 		goto done;
 
 	dmaengine_tx_status(dma->chan, dma->cookie, &state);
 
-	dma_unmap_single(port->dev, dma->phys, dma->count, dma->dir);
+	dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
 
 	val = msm_read(port, UARTDM_DMEN);
 	val &= ~dma->enable_bit;
@@ -464,9 +478,9 @@ static void msm_complete_tx_dma(void *args)
 		msm_write(port, MSM_UART_CR_TX_ENABLE, MSM_UART_CR);
 	}
 
-	count = dma->count - state.residue;
+	count = sg_dma_len(&dma->tx_sg) - state.residue;
 	uart_xmit_advance(port, count);
-	dma->count = 0;
+	sg_init_table(&dma->tx_sg, 1);
 
 	/* Restore "Tx FIFO below watermark" interrupt */
 	msm_port->imr |= MSM_UART_IMR_TXLEV;
@@ -485,19 +499,18 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 	struct circ_buf *xmit = &msm_port->uart.state->xmit;
 	struct uart_port *port = &msm_port->uart;
 	struct msm_dma *dma = &msm_port->tx_dma;
-	void *cpu_addr;
 	int ret;
 	u32 val;
 
-	cpu_addr = &xmit->buf[xmit->tail];
+	sg_init_table(&dma->tx_sg, 1);
+	sg_set_buf(&dma->tx_sg, &xmit->buf[xmit->tail], count);
 
-	dma->phys = dma_map_single(port->dev, cpu_addr, count, dma->dir);
-	ret = dma_mapping_error(port->dev, dma->phys);
+	ret = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
 	if (ret)
 		return ret;
 
-	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
-						count, DMA_MEM_TO_DEV,
+	dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
+						DMA_MEM_TO_DEV,
 						DMA_PREP_INTERRUPT |
 						DMA_PREP_FENCE);
 	if (!dma->desc) {
@@ -520,8 +533,6 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 	msm_port->imr &= ~MSM_UART_IMR_TXLEV;
 	msm_write(port, msm_port->imr, MSM_UART_IMR);
 
-	dma->count = count;
-
 	val = msm_read(port, UARTDM_DMEN);
 	val |= dma->enable_bit;
 
@@ -536,7 +547,8 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 	dma_async_issue_pending(dma->chan);
 	return 0;
 unmap:
-	dma_unmap_single(port->dev, dma->phys, count, dma->dir);
+	dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+	sg_init_table(&dma->tx_sg, 1);
 	return ret;
 }
 
@@ -553,7 +565,7 @@ static void msm_complete_rx_dma(void *args)
 	uart_port_lock_irqsave(port, &flags);
 
 	/* Already stopped */
-	if (!dma->count)
+	if (!dma->rx.count)
 		goto done;
 
 	val = msm_read(port, UARTDM_DMEN);
@@ -570,14 +582,14 @@ static void msm_complete_rx_dma(void *args)
 
 	port->icount.rx += count;
 
-	dma->count = 0;
+	dma->rx.count = 0;
 
-	dma_unmap_single(port->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+	dma_unmap_single(port->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
 
 	for (i = 0; i < count; i++) {
 		char flag = TTY_NORMAL;
 
-		if (msm_port->break_detected && dma->virt[i] == 0) {
+		if (msm_port->break_detected && dma->rx.virt[i] == 0) {
 			port->icount.brk++;
 			flag = TTY_BREAK;
 			msm_port->break_detected = false;
@@ -588,9 +600,9 @@ static void msm_complete_rx_dma(void *args)
 		if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK))
 			flag = TTY_NORMAL;
 
-		sysrq = uart_prepare_sysrq_char(port, dma->virt[i]);
+		sysrq = uart_prepare_sysrq_char(port, dma->rx.virt[i]);
 		if (!sysrq)
-			tty_insert_flip_char(tport, dma->virt[i], flag);
+			tty_insert_flip_char(tport, dma->rx.virt[i], flag);
 	}
 
 	msm_start_rx_dma(msm_port);
@@ -614,13 +626,13 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 	if (!dma->chan)
 		return;
 
-	dma->phys = dma_map_single(uart->dev, dma->virt,
+	dma->rx.phys = dma_map_single(uart->dev, dma->rx.virt,
 				   UARTDM_RX_SIZE, dma->dir);
-	ret = dma_mapping_error(uart->dev, dma->phys);
+	ret = dma_mapping_error(uart->dev, dma->rx.phys);
 	if (ret)
 		goto sw_mode;
 
-	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
+	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->rx.phys,
 						UARTDM_RX_SIZE, DMA_DEV_TO_MEM,
 						DMA_PREP_INTERRUPT);
 	if (!dma->desc)
@@ -648,7 +660,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 
 	msm_write(uart, msm_port->imr, MSM_UART_IMR);
 
-	dma->count = UARTDM_RX_SIZE;
+	dma->rx.count = UARTDM_RX_SIZE;
 
 	dma_async_issue_pending(dma->chan);
 
@@ -668,7 +680,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 
 	return;
 unmap:
-	dma_unmap_single(uart->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+	dma_unmap_single(uart->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
 
 sw_mode:
 	/*
@@ -955,7 +967,7 @@ static irqreturn_t msm_uart_irq(int irq, void *dev_id)
 	}
 
 	if (misr & (MSM_UART_IMR_RXLEV | MSM_UART_IMR_RXSTALE)) {
-		if (dma->count) {
+		if (dma->rx.count) {
 			val = MSM_UART_CR_CMD_STALE_EVENT_DISABLE;
 			msm_write(port, val, MSM_UART_CR);
 			val = MSM_UART_CR_CMD_RESET_STALE_INT;
-- 
2.44.0

Re: [RFT 00/15] tty: serial: switch from circ_buf to kfifo

[Richard Genoud]

Le 19/03/2024 à 10:52, Jiri Slaby (SUSE) a écrit :
> This series switches tty serial layer to use kfifo instead of circ_buf.
> Excerpt from the switching patch:
> """
> Switch from struct circ_buf to proper kfifo. kfifo provides much better
> API, esp. when wrap-around of the buffer needs to be taken into account.
> Look at pl011_dma_tx_refill() or cpm_uart_tx_pump() changes for example.
> 
> Kfifo API can also fill in scatter-gather DMA structures, so it easier
> for that use case too. Look at lpuart_dma_tx() for example. Note that
> not all drivers can be converted to that (like atmel_serial), they
> handle DMA specially.
> 
> Note that usb-serial uses kfifo for TX for ages.
> """
> 
> This is Request for Testing as I cannot test all the changes
> (obviously). So please test your HW's serial properly.

Tested-by: Richard Genoud <richard.genoud@gmail.com> # on at91sam9g20-ek sama5d3_xplained and sama5d2_xplained