From 1788cf6a91d9fa9aa61fc2917afe192c23d67f6a Mon Sep 17 00:00:00 2001 From: "Jiri Slaby (SUSE)" Date: Fri, 5 Apr 2024 08:08:23 +0200 Subject: tty: serial: switch from circ_buf to kfifo MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. omap needed a bit more care as it needs to put a char into FIFO to start the DMA transfer when OMAP_DMA_TX_KICK is set. In that case, we have to do kfifo_dma_out_prepare twice: once to find out the tx_size (to find out if it is worths to do DMA at all -- size >= 4), the second time for the actual transfer. All traces of circ_buf are removed from serial_core.h (and its struct uart_state). Signed-off-by: Jiri Slaby (SUSE) Cc: Al Cooper Cc: Matthias Brugger Cc: AngeloGioacchino Del Regno Cc: Kumaravel Thiagarajan Cc: Tharun Kumar P Cc: Russell King Cc: Vineet Gupta Cc: Richard Genoud Cc: Nicolas Ferre Cc: Alexandre Belloni Cc: Claudiu Beznea Cc: Alexander Shiyan Cc: Baruch Siach Cc: Maciej W. Rozycki Cc: Shawn Guo Cc: Sascha Hauer Cc: Fabio Estevam Cc: Neil Armstrong Cc: Kevin Hilman Cc: Jerome Brunet Cc: Martin Blumenstingl Cc: Taichi Sugaya Cc: Takao Orito Cc: Bjorn Andersson Cc: Konrad Dybcio Cc: Pali Rohár Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Aneesh Kumar K.V Cc: Naveen N. Rao Cc: Manivannan Sadhasivam Cc: Krzysztof Kozlowski Cc: Alim Akhtar Cc: Laxman Dewangan Cc: Thierry Reding Cc: Jonathan Hunter Cc: Orson Zhai Cc: Baolin Wang Cc: Chunyan Zhang Cc: Patrice Chotard Cc: Maxime Coquelin Cc: Alexandre Torgue Cc: David S. Miller Cc: Hammer Hsieh Cc: Peter Korsgaard Cc: Timur Tabi Cc: Michal Simek Cc: Sumit Semwal Cc: Christian König Link: https://lore.kernel.org/r/20240405060826.2521-13-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/stm32-usart.c | 52 ++++++++++++++++------------------------ 1 file changed, 20 insertions(+), 32 deletions(-) (limited to 'drivers/tty/serial/stm32-usart.c') diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 58d169e5c1db..8c66abcfe6ca 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -696,18 +696,23 @@ static void stm32_usart_transmit_chars_pio(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - struct circ_buf *xmit = &port->state->xmit; + struct tty_port *tport = &port->state->port; + + while (1) { + unsigned char ch; - while (!uart_circ_empty(xmit)) { /* Check that TDR is empty before filling FIFO */ if (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE)) break; - writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr); - uart_xmit_advance(port, 1); + + if (!uart_fifo_get(port, &ch)) + break; + + writel_relaxed(ch, port->membase + ofs->tdr); } /* rely on TXE irq (mask or unmask) for sending remaining data */ - if (uart_circ_empty(xmit)) + if (kfifo_is_empty(&tport->xmit_fifo)) stm32_usart_tx_interrupt_disable(port); else stm32_usart_tx_interrupt_enable(port); @@ -716,7 +721,7 @@ static void stm32_usart_transmit_chars_pio(struct uart_port *port) static void stm32_usart_transmit_chars_dma(struct uart_port *port) { struct stm32_port *stm32port = to_stm32_port(port); - struct circ_buf *xmit = &port->state->xmit; + struct tty_port *tport = &port->state->port; struct dma_async_tx_descriptor *desc = NULL; unsigned int count; int ret; @@ -728,25 +733,8 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) return; } - count = uart_circ_chars_pending(xmit); - - if (count > TX_BUF_L) - count = TX_BUF_L; - - if (xmit->tail < xmit->head) { - memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], count); - } else { - size_t one = UART_XMIT_SIZE - xmit->tail; - size_t two; - - if (one > count) - one = count; - two = count - one; - - memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], one); - if (two) - memcpy(&stm32port->tx_buf[one], &xmit->buf[0], two); - } + count = kfifo_out_peek(&tport->xmit_fifo, &stm32port->tx_buf[0], + TX_BUF_L); desc = dmaengine_prep_slave_single(stm32port->tx_ch, stm32port->tx_dma_buf, @@ -792,14 +780,14 @@ static void stm32_usart_transmit_chars(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - struct circ_buf *xmit = &port->state->xmit; + struct tty_port *tport = &port->state->port; u32 isr; int ret; if (!stm32_port->hw_flow_control && port->rs485.flags & SER_RS485_ENABLED && (port->x_char || - !(uart_circ_empty(xmit) || uart_tx_stopped(port)))) { + !(kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)))) { stm32_usart_tc_interrupt_disable(port); stm32_usart_rs485_rts_enable(port); } @@ -826,7 +814,7 @@ static void stm32_usart_transmit_chars(struct uart_port *port) return; } - if (uart_circ_empty(xmit) || uart_tx_stopped(port)) { + if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) { stm32_usart_tx_interrupt_disable(port); return; } @@ -841,10 +829,10 @@ static void stm32_usart_transmit_chars(struct uart_port *port) else stm32_usart_transmit_chars_pio(port); - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS) uart_write_wakeup(port); - if (uart_circ_empty(xmit)) { + if (kfifo_is_empty(&tport->xmit_fifo)) { stm32_usart_tx_interrupt_disable(port); if (!stm32_port->hw_flow_control && port->rs485.flags & SER_RS485_ENABLED) { @@ -967,9 +955,9 @@ static void stm32_usart_stop_tx(struct uart_port *port) /* There are probably characters waiting to be transmitted. */ static void stm32_usart_start_tx(struct uart_port *port) { - struct circ_buf *xmit = &port->state->xmit; + struct tty_port *tport = &port->state->port; - if (uart_circ_empty(xmit) && !port->x_char) { + if (kfifo_is_empty(&tport->xmit_fifo) && !port->x_char) { stm32_usart_rs485_rts_disable(port); return; } -- cgit v1.2.3-59-g8ed1b From 13c785323b36b845300b256d0e5963c3727667d7 Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Wed, 17 Apr 2024 11:03:27 +0200 Subject: serial: stm32: Return IRQ_NONE in the ISR if no handling happend MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If there is a stuck irq that the handler doesn't address, returning IRQ_HANDLED unconditionally makes it impossible for the irq core to detect the problem and disable the irq. So only return IRQ_HANDLED if an event was handled. A stuck irq is still problematic, but with this change at least it only makes the UART nonfunctional instead of occupying the (usually only) CPU by 100% and so stall the whole machine. Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/5f92603d0dfd8a5b8014b2b10a902d91e0bb881f.1713344161.git.u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/stm32-usart.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'drivers/tty/serial/stm32-usart.c') diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 58d169e5c1db..d60cbac69194 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -861,6 +861,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; u32 sr; unsigned int size; + irqreturn_t ret = IRQ_NONE; sr = readl_relaxed(port->membase + ofs->isr); @@ -869,11 +870,14 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) (sr & USART_SR_TC)) { stm32_usart_tc_interrupt_disable(port); stm32_usart_rs485_rts_disable(port); + ret = IRQ_HANDLED; } - if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG) + if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG) { writel_relaxed(USART_ICR_RTOCF, port->membase + ofs->icr); + ret = IRQ_HANDLED; + } if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG) { /* Clear wake up flag and disable wake up interrupt */ @@ -882,6 +886,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE); if (irqd_is_wakeup_set(irq_get_irq_data(port->irq))) pm_wakeup_event(tport->tty->dev, 0); + ret = IRQ_HANDLED; } /* @@ -896,6 +901,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) uart_unlock_and_check_sysrq(port); if (size) tty_flip_buffer_push(tport); + ret = IRQ_HANDLED; } } @@ -903,6 +909,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) uart_port_lock(port); stm32_usart_transmit_chars(port); uart_port_unlock(port); + ret = IRQ_HANDLED; } /* Receiver timeout irq for DMA RX */ @@ -912,9 +919,10 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) uart_unlock_and_check_sysrq(port); if (size) tty_flip_buffer_push(tport); + ret = IRQ_HANDLED; } - return IRQ_HANDLED; + return ret; } static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl) -- cgit v1.2.3-59-g8ed1b From ea2624b5b829b8f93c0dce25721d835969b34faf Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Wed, 17 Apr 2024 11:03:28 +0200 Subject: serial: stm32: Reset .throttled state in .startup() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When an UART is opened that still has .throttled set from a previous open, the RX interrupt is enabled but the irq handler doesn't consider it. This easily results in a stuck irq with the effect to occupy the CPU in a tight loop. So reset the throttle state in .startup() to ensure that RX irqs are handled. Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/a784f80d3414f7db723b2ec66efc56e1ad666cbf.1713344161.git.u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/stm32-usart.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/tty/serial/stm32-usart.c') diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index d60cbac69194..4fa5a03ebac0 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1092,6 +1092,7 @@ static int stm32_usart_startup(struct uart_port *port) val |= USART_CR2_SWAP; writel_relaxed(val, port->membase + ofs->cr2); } + stm32_port->throttled = false; /* RX FIFO Flush */ if (ofs->rqr != UNDEF_REG) -- cgit v1.2.3-59-g8ed1b