From: Alexandre TORGUE Date: Thu, 15 Sep 2016 16:42:40 +0000 (+0200) Subject: serial: stm32: adding dma support X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3489187204eb75e5635d8836babfd0a18be613f4;p=linux-beck.git serial: stm32: adding dma support This patch adds dma mode support for rx and tx with pio mode as fallback in case of dma error. Signed-off-by: Gerald Baeza Signed-off-by: Alexandre TORGUE Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 520e7defc08d..24c4d821472a 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -11,26 +11,31 @@ #define SUPPORT_SYSRQ #endif -#include -#include +#include #include -#include -#include +#include +#include +#include +#include #include +#include #include -#include -#include -#include -#include -#include +#include #include #include +#include +#include #include -#include +#include +#include +#include +#include +#include #include "stm32-usart.h" static void stm32_stop_tx(struct uart_port *port); +static void stm32_transmit_chars(struct uart_port *port); static inline struct stm32_port *to_stm32_port(struct uart_port *port) { @@ -55,7 +60,48 @@ static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits) writel_relaxed(val, port->membase + reg); } -static void stm32_receive_chars(struct uart_port *port) +int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res, + bool threaded) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + enum dma_status status; + struct dma_tx_state state; + + *sr = readl_relaxed(port->membase + ofs->isr); + + if (threaded && stm32_port->rx_ch) { + status = dmaengine_tx_status(stm32_port->rx_ch, + stm32_port->rx_ch->cookie, + &state); + if ((status == DMA_IN_PROGRESS) && + (*last_res != state.residue)) + return 1; + else + return 0; + } else if (*sr & USART_SR_RXNE) { + return 1; + } + return 0; +} + +unsigned long stm32_get_char(struct uart_port *port, u32 *sr, int *last_res) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + unsigned long c; + + if (stm32_port->rx_ch) { + c = stm32_port->rx_buf[RX_BUF_L - (*last_res)--]; + if ((*last_res) == 0) + *last_res = RX_BUF_L; + return c; + } else { + return readl_relaxed(port->membase + ofs->rdr); + } +} + +static void stm32_receive_chars(struct uart_port *port, bool threaded) { struct tty_port *tport = &port->state->port; struct stm32_port *stm32_port = to_stm32_port(port); @@ -63,13 +109,14 @@ static void stm32_receive_chars(struct uart_port *port) unsigned long c; u32 sr; char flag; + static int last_res = RX_BUF_L; if (port->irq_wake) pm_wakeup_event(tport->tty->dev, 0); - while ((sr = readl_relaxed(port->membase + ofs->isr)) & USART_SR_RXNE) { + while (stm32_pending_rx(port, &sr, &last_res, threaded)) { sr |= USART_SR_DUMMY_RX; - c = readl_relaxed(port->membase + ofs->rdr); + c = stm32_get_char(port, &sr, &last_res); flag = TTY_NORMAL; port->icount.rx++; @@ -110,6 +157,124 @@ static void stm32_receive_chars(struct uart_port *port) spin_lock(&port->lock); } +static void stm32_tx_dma_complete(void *arg) +{ + struct uart_port *port = arg; + struct stm32_port *stm32port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32port->info->ofs; + unsigned int isr; + int ret; + + ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, + isr, + (isr & USART_SR_TC), + 10, 100000); + + if (ret) + dev_err(port->dev, "terminal count not set\n"); + + if (ofs->icr == UNDEF_REG) + stm32_clr_bits(port, ofs->isr, USART_SR_TC); + else + stm32_set_bits(port, ofs->icr, USART_CR_TC); + + stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + stm32port->tx_dma_busy = false; + + /* Let's see if we have pending data to send */ + stm32_transmit_chars(port); +} + +static void stm32_transmit_chars_pio(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + struct circ_buf *xmit = &port->state->xmit; + unsigned int isr; + int ret; + + if (stm32_port->tx_dma_busy) { + stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + stm32_port->tx_dma_busy = false; + } + + ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, + isr, + (isr & USART_SR_TXE), + 10, 100); + + if (ret) + dev_err(port->dev, "tx empty not set\n"); + + stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE); + + writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr); + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + port->icount.tx++; +} + +static void stm32_transmit_chars_dma(struct uart_port *port) +{ + struct stm32_port *stm32port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32port->info->ofs; + struct circ_buf *xmit = &port->state->xmit; + struct dma_async_tx_descriptor *desc = NULL; + dma_cookie_t cookie; + unsigned int count, i; + + if (stm32port->tx_dma_busy) + return; + + stm32port->tx_dma_busy = true; + + 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); + } + + desc = dmaengine_prep_slave_single(stm32port->tx_ch, + stm32port->tx_dma_buf, + count, + DMA_MEM_TO_DEV, + DMA_PREP_INTERRUPT); + + if (!desc) { + for (i = count; i > 0; i--) + stm32_transmit_chars_pio(port); + return; + } + + desc->callback = stm32_tx_dma_complete; + desc->callback_param = port; + + /* Push current DMA TX transaction in the pending queue */ + cookie = dmaengine_submit(desc); + + /* Issue pending DMA TX requests */ + dma_async_issue_pending(stm32port->tx_ch); + + stm32_clr_bits(port, ofs->isr, USART_SR_TC); + stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT); + + xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1); + port->icount.tx += count; +} + static void stm32_transmit_chars(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); @@ -117,9 +282,13 @@ static void stm32_transmit_chars(struct uart_port *port) struct circ_buf *xmit = &port->state->xmit; if (port->x_char) { + if (stm32_port->tx_dma_busy) + stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT); writel_relaxed(port->x_char, port->membase + ofs->tdr); port->x_char = 0; port->icount.tx++; + if (stm32_port->tx_dma_busy) + stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT); return; } @@ -133,9 +302,10 @@ static void stm32_transmit_chars(struct uart_port *port) return; } - writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr); - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); - port->icount.tx++; + if (stm32_port->tx_ch) + stm32_transmit_chars_dma(port); + else + stm32_transmit_chars_pio(port); if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); @@ -151,16 +321,30 @@ static irqreturn_t stm32_interrupt(int irq, void *ptr) struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; u32 sr; - spin_lock(&port->lock); - sr = readl_relaxed(port->membase + ofs->isr); - if (sr & USART_SR_RXNE) - stm32_receive_chars(port); + if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch)) + stm32_receive_chars(port, false); - if (sr & USART_SR_TXE) + if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) stm32_transmit_chars(port); + if (stm32_port->rx_ch) + return IRQ_WAKE_THREAD; + else + return IRQ_HANDLED; +} + +static irqreturn_t stm32_threaded_interrupt(int irq, void *ptr) +{ + struct uart_port *port = ptr; + struct stm32_port *stm32_port = to_stm32_port(port); + + spin_lock(&port->lock); + + if (stm32_port->rx_ch) + stm32_receive_chars(port, true); + spin_unlock(&port->lock); return IRQ_HANDLED; @@ -203,14 +387,12 @@ static void stm32_stop_tx(struct uart_port *port) /* There are probably characters waiting to be transmitted. */ static void stm32_start_tx(struct uart_port *port) { - struct stm32_port *stm32_port = to_stm32_port(port); - struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; struct circ_buf *xmit = &port->state->xmit; if (uart_circ_empty(xmit)) return; - stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE | USART_CR1_TE); + stm32_transmit_chars(port); } /* Throttle the remote when input buffer is about to overflow. */ @@ -259,7 +441,9 @@ static int stm32_startup(struct uart_port *port) u32 val; int ret; - ret = request_irq(port->irq, stm32_interrupt, 0, name, port); + ret = request_threaded_irq(port->irq, stm32_interrupt, + stm32_threaded_interrupt, + IRQF_NO_SUSPEND, name, port); if (ret) return ret; @@ -376,6 +560,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, if ((termios->c_cflag & CREAD) == 0) port->ignore_status_mask |= USART_SR_DUMMY_RX; + if (stm32_port->rx_ch) + cr3 |= USART_CR3_DMAR; + writel_relaxed(cr3, port->membase + ofs->cr3); writel_relaxed(cr2, port->membase + ofs->cr2); writel_relaxed(cr1, port->membase + ofs->cr1); @@ -523,6 +710,129 @@ static const struct of_device_id stm32_match[] = { MODULE_DEVICE_TABLE(of, stm32_match); #endif +static int stm32_of_dma_rx_probe(struct stm32_port *stm32port, + struct platform_device *pdev) +{ + struct stm32_usart_offsets *ofs = &stm32port->info->ofs; + struct uart_port *port = &stm32port->port; + struct device *dev = &pdev->dev; + struct dma_slave_config config; + struct dma_async_tx_descriptor *desc = NULL; + dma_cookie_t cookie; + int ret; + + /* Request DMA RX channel */ + stm32port->rx_ch = dma_request_slave_channel(dev, "rx"); + if (!stm32port->rx_ch) { + dev_info(dev, "rx dma alloc failed\n"); + return -ENODEV; + } + stm32port->rx_buf = dma_alloc_coherent(&pdev->dev, RX_BUF_L, + &stm32port->rx_dma_buf, + GFP_KERNEL); + if (!stm32port->rx_buf) { + ret = -ENOMEM; + goto alloc_err; + } + + /* Configure DMA channel */ + memset(&config, 0, sizeof(config)); + config.src_addr = (dma_addr_t)port->membase + ofs->rdr; + config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + + ret = dmaengine_slave_config(stm32port->rx_ch, &config); + if (ret < 0) { + dev_err(dev, "rx dma channel config failed\n"); + ret = -ENODEV; + goto config_err; + } + + /* Prepare a DMA cyclic transaction */ + desc = dmaengine_prep_dma_cyclic(stm32port->rx_ch, + stm32port->rx_dma_buf, + RX_BUF_L, RX_BUF_P, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + if (!desc) { + dev_err(dev, "rx dma prep cyclic failed\n"); + ret = -ENODEV; + goto config_err; + } + + /* No callback as dma buffer is drained on usart interrupt */ + desc->callback = NULL; + desc->callback_param = NULL; + + /* Push current DMA transaction in the pending queue */ + cookie = dmaengine_submit(desc); + + /* Issue pending DMA requests */ + dma_async_issue_pending(stm32port->rx_ch); + + return 0; + +config_err: + dma_free_coherent(&pdev->dev, + RX_BUF_L, stm32port->rx_buf, + stm32port->rx_dma_buf); + +alloc_err: + dma_release_channel(stm32port->rx_ch); + stm32port->rx_ch = NULL; + + return ret; +} + +static int stm32_of_dma_tx_probe(struct stm32_port *stm32port, + struct platform_device *pdev) +{ + struct stm32_usart_offsets *ofs = &stm32port->info->ofs; + struct uart_port *port = &stm32port->port; + struct device *dev = &pdev->dev; + struct dma_slave_config config; + int ret; + + stm32port->tx_dma_busy = false; + + /* Request DMA TX channel */ + stm32port->tx_ch = dma_request_slave_channel(dev, "tx"); + if (!stm32port->tx_ch) { + dev_info(dev, "tx dma alloc failed\n"); + return -ENODEV; + } + stm32port->tx_buf = dma_alloc_coherent(&pdev->dev, TX_BUF_L, + &stm32port->tx_dma_buf, + GFP_KERNEL); + if (!stm32port->tx_buf) { + ret = -ENOMEM; + goto alloc_err; + } + + /* Configure DMA channel */ + memset(&config, 0, sizeof(config)); + config.dst_addr = (dma_addr_t)port->membase + ofs->tdr; + config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + + ret = dmaengine_slave_config(stm32port->tx_ch, &config); + if (ret < 0) { + dev_err(dev, "tx dma channel config failed\n"); + ret = -ENODEV; + goto config_err; + } + + return 0; + +config_err: + dma_free_coherent(&pdev->dev, + TX_BUF_L, stm32port->tx_buf, + stm32port->tx_dma_buf); + +alloc_err: + dma_release_channel(stm32port->tx_ch); + stm32port->tx_ch = NULL; + + return ret; +} + static int stm32_serial_probe(struct platform_device *pdev) { const struct of_device_id *match; @@ -547,6 +857,14 @@ static int stm32_serial_probe(struct platform_device *pdev) if (ret) return ret; + ret = stm32_of_dma_rx_probe(stm32port, pdev); + if (ret) + dev_info(&pdev->dev, "interrupt mode used for rx (no dma)\n"); + + ret = stm32_of_dma_tx_probe(stm32port, pdev); + if (ret) + dev_info(&pdev->dev, "interrupt mode used for tx (no dma)\n"); + platform_set_drvdata(pdev, &stm32port->port); return 0; @@ -556,6 +874,27 @@ static int stm32_serial_remove(struct platform_device *pdev) { struct uart_port *port = platform_get_drvdata(pdev); struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + + stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR); + + if (stm32_port->rx_ch) + dma_release_channel(stm32_port->rx_ch); + + if (stm32_port->rx_dma_buf) + dma_free_coherent(&pdev->dev, + RX_BUF_L, stm32_port->rx_buf, + stm32_port->rx_dma_buf); + + stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + + if (stm32_port->tx_ch) + dma_release_channel(stm32_port->tx_ch); + + if (stm32_port->tx_dma_buf) + dma_free_coherent(&pdev->dev, + TX_BUF_L, stm32_port->tx_buf, + stm32_port->tx_dma_buf); clk_disable_unprepare(stm32_port->clk); diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h index 75f8388c91df..41d974923102 100644 --- a/drivers/tty/serial/stm32-usart.h +++ b/drivers/tty/serial/stm32-usart.h @@ -99,6 +99,9 @@ struct stm32_usart_info stm32f7_info = { /* Dummy bits */ #define USART_SR_DUMMY_RX BIT(16) +/* USART_ICR (F7) */ +#define USART_CR_TC BIT(6) + /* USART_DR */ #define USART_DR_MASK GENMASK(8, 0) @@ -204,10 +207,21 @@ struct stm32_usart_info stm32f7_info = { #define STM32_SERIAL_NAME "ttyS" #define STM32_MAX_PORTS 6 +#define RX_BUF_L 200 /* dma rx buffer length */ +#define RX_BUF_P RX_BUF_L /* dma rx buffer period */ +#define TX_BUF_L 200 /* dma tx buffer length */ + struct stm32_port { struct uart_port port; struct clk *clk; struct stm32_usart_info *info; + struct dma_chan *rx_ch; /* dma rx channel */ + dma_addr_t rx_dma_buf; /* dma rx buffer bus address */ + unsigned char *rx_buf; /* dma rx buffer cpu address */ + struct dma_chan *tx_ch; /* dma tx channel */ + dma_addr_t tx_dma_buf; /* dma tx buffer bus address */ + unsigned char *tx_buf; /* dma tx buffer cpu address */ + bool tx_dma_busy; /* dma tx busy */ bool hw_flow_control; };