v4.19.13 snapshot.
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
new file mode 100644
index 0000000..e8d7a7b
--- /dev/null
+++ b/drivers/tty/serial/stm32-usart.c
@@ -0,0 +1,1283 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Copyright (C) STMicroelectronics SA 2017
+ * Authors: Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ * Gerald Baeza <gerald.baeza@st.com>
+ *
+ * Inspired by st-asc.c from STMicroelectronics (c)
+ */
+
+#if defined(CONFIG_SERIAL_STM32_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/dma-direction.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/spinlock.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/tty.h>
+
+#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)
+{
+ return container_of(port, struct stm32_port, port);
+}
+
+static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits)
+{
+ u32 val;
+
+ val = readl_relaxed(port->membase + reg);
+ val |= bits;
+ writel_relaxed(val, port->membase + reg);
+}
+
+static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
+{
+ u32 val;
+
+ val = readl_relaxed(port->membase + reg);
+ val &= ~bits;
+ writel_relaxed(val, port->membase + reg);
+}
+
+static void stm32_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
+ u32 delay_DDE, u32 baud)
+{
+ u32 rs485_deat_dedt;
+ u32 rs485_deat_dedt_max = (USART_CR1_DEAT_MASK >> USART_CR1_DEAT_SHIFT);
+ bool over8;
+
+ *cr3 |= USART_CR3_DEM;
+ over8 = *cr1 & USART_CR1_OVER8;
+
+ if (over8)
+ rs485_deat_dedt = delay_ADE * baud * 8;
+ else
+ rs485_deat_dedt = delay_ADE * baud * 16;
+
+ rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
+ rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
+ rs485_deat_dedt_max : rs485_deat_dedt;
+ rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEAT_SHIFT) &
+ USART_CR1_DEAT_MASK;
+ *cr1 |= rs485_deat_dedt;
+
+ if (over8)
+ rs485_deat_dedt = delay_DDE * baud * 8;
+ else
+ rs485_deat_dedt = delay_DDE * baud * 16;
+
+ rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
+ rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
+ rs485_deat_dedt_max : rs485_deat_dedt;
+ rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEDT_SHIFT) &
+ USART_CR1_DEDT_MASK;
+ *cr1 |= rs485_deat_dedt;
+}
+
+static int stm32_config_rs485(struct uart_port *port,
+ struct serial_rs485 *rs485conf)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ u32 usartdiv, baud, cr1, cr3;
+ bool over8;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+
+ port->rs485 = *rs485conf;
+
+ rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ cr1 = readl_relaxed(port->membase + ofs->cr1);
+ cr3 = readl_relaxed(port->membase + ofs->cr3);
+ usartdiv = readl_relaxed(port->membase + ofs->brr);
+ usartdiv = usartdiv & GENMASK(15, 0);
+ over8 = cr1 & USART_CR1_OVER8;
+
+ if (over8)
+ usartdiv = usartdiv | (usartdiv & GENMASK(4, 0))
+ << USART_BRR_04_R_SHIFT;
+
+ baud = DIV_ROUND_CLOSEST(port->uartclk, usartdiv);
+ stm32_config_reg_rs485(&cr1, &cr3,
+ rs485conf->delay_rts_before_send,
+ rs485conf->delay_rts_after_send, baud);
+
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ cr3 &= ~USART_CR3_DEP;
+ rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
+ } else {
+ cr3 |= USART_CR3_DEP;
+ rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
+ }
+
+ writel_relaxed(cr3, port->membase + ofs->cr3);
+ writel_relaxed(cr1, port->membase + ofs->cr1);
+ } else {
+ stm32_clr_bits(port, ofs->cr3, USART_CR3_DEM | USART_CR3_DEP);
+ stm32_clr_bits(port, ofs->cr1,
+ USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+ }
+
+ stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ return 0;
+}
+
+static int stm32_init_rs485(struct uart_port *port,
+ struct platform_device *pdev)
+{
+ struct serial_rs485 *rs485conf = &port->rs485;
+
+ rs485conf->flags = 0;
+ rs485conf->delay_rts_before_send = 0;
+ rs485conf->delay_rts_after_send = 0;
+
+ if (!pdev->dev.of_node)
+ return -ENODEV;
+
+ uart_get_rs485_mode(&pdev->dev, rs485conf);
+
+ return 0;
+}
+
+static 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;
+}
+
+static 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);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ unsigned long c;
+ u32 sr;
+ char flag;
+
+ if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
+ pm_wakeup_event(tport->tty->dev, 0);
+
+ while (stm32_pending_rx(port, &sr, &stm32_port->last_res, threaded)) {
+ sr |= USART_SR_DUMMY_RX;
+ c = stm32_get_char(port, &sr, &stm32_port->last_res);
+ flag = TTY_NORMAL;
+ port->icount.rx++;
+
+ if (sr & USART_SR_ERR_MASK) {
+ if (sr & USART_SR_LBD) {
+ port->icount.brk++;
+ if (uart_handle_break(port))
+ continue;
+ } else if (sr & USART_SR_ORE) {
+ if (ofs->icr != UNDEF_REG)
+ writel_relaxed(USART_ICR_ORECF,
+ port->membase +
+ ofs->icr);
+ port->icount.overrun++;
+ } else if (sr & USART_SR_PE) {
+ port->icount.parity++;
+ } else if (sr & USART_SR_FE) {
+ port->icount.frame++;
+ }
+
+ sr &= port->read_status_mask;
+
+ if (sr & USART_SR_LBD)
+ flag = TTY_BREAK;
+ else if (sr & USART_SR_PE)
+ flag = TTY_PARITY;
+ else if (sr & USART_SR_FE)
+ flag = TTY_FRAME;
+ }
+
+ if (uart_handle_sysrq_char(port, c))
+ continue;
+ uart_insert_char(port, sr, USART_SR_ORE, c, flag);
+ }
+
+ spin_unlock(&port->lock);
+ tty_flip_buffer_push(tport);
+ 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, 100000);
+
+ 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);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ 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;
+ }
+
+ if (uart_tx_stopped(port)) {
+ stm32_stop_tx(port);
+ return;
+ }
+
+ if (uart_circ_empty(xmit)) {
+ stm32_stop_tx(port);
+ return;
+ }
+
+ 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);
+
+ if (uart_circ_empty(xmit))
+ stm32_stop_tx(port);
+}
+
+static irqreturn_t stm32_interrupt(int irq, void *ptr)
+{
+ struct uart_port *port = ptr;
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ 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_WUF) && (ofs->icr != UNDEF_REG))
+ writel_relaxed(USART_ICR_WUCF,
+ port->membase + ofs->icr);
+
+ if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))
+ stm32_receive_chars(port, false);
+
+ if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch))
+ stm32_transmit_chars(port);
+
+ spin_unlock(&port->lock);
+
+ 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;
+}
+
+static unsigned int stm32_tx_empty(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ return readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE;
+}
+
+static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
+ stm32_set_bits(port, ofs->cr3, USART_CR3_RTSE);
+ else
+ stm32_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
+}
+
+static unsigned int stm32_get_mctrl(struct uart_port *port)
+{
+ /* This routine is used to get signals of: DCD, DSR, RI, and CTS */
+ return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+}
+
+/* Transmit stop */
+static void stm32_stop_tx(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
+}
+
+/* There are probably characters waiting to be transmitted. */
+static void stm32_start_tx(struct uart_port *port)
+{
+ struct circ_buf *xmit = &port->state->xmit;
+
+ if (uart_circ_empty(xmit))
+ return;
+
+ stm32_transmit_chars(port);
+}
+
+/* Throttle the remote when input buffer is about to overflow. */
+static void stm32_throttle(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* Unthrottle the remote, the input buffer can now accept data. */
+static void stm32_unthrottle(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ stm32_set_bits(port, ofs->cr1, USART_CR1_RXNEIE);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* Receive stop */
+static void stm32_stop_rx(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
+}
+
+/* Handle breaks - ignored by us */
+static void stm32_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static int stm32_startup(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ const char *name = to_platform_device(port->dev)->name;
+ u32 val;
+ int ret;
+
+ ret = request_threaded_irq(port->irq, stm32_interrupt,
+ stm32_threaded_interrupt,
+ IRQF_NO_SUSPEND, name, port);
+ if (ret)
+ return ret;
+
+ if (cfg->has_wakeup && stm32_port->wakeirq >= 0) {
+ ret = dev_pm_set_dedicated_wake_irq(port->dev,
+ stm32_port->wakeirq);
+ if (ret) {
+ free_irq(port->irq, port);
+ return ret;
+ }
+ }
+
+ val = USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
+ if (stm32_port->fifoen)
+ val |= USART_CR1_FIFOEN;
+ stm32_set_bits(port, ofs->cr1, val);
+
+ return 0;
+}
+
+static void stm32_shutdown(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ u32 val;
+
+ val = USART_CR1_TXEIE | USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
+ val |= BIT(cfg->uart_enable_bit);
+ if (stm32_port->fifoen)
+ val |= USART_CR1_FIFOEN;
+ stm32_clr_bits(port, ofs->cr1, val);
+
+ dev_pm_clear_wake_irq(port->dev);
+ free_irq(port->irq, port);
+}
+
+static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
+ struct ktermios *old)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ struct serial_rs485 *rs485conf = &port->rs485;
+ unsigned int baud;
+ u32 usartdiv, mantissa, fraction, oversampling;
+ tcflag_t cflag = termios->c_cflag;
+ u32 cr1, cr2, cr3;
+ unsigned long flags;
+
+ if (!stm32_port->hw_flow_control)
+ cflag &= ~CRTSCTS;
+
+ baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 8);
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ /* Stop serial port and reset value */
+ writel_relaxed(0, port->membase + ofs->cr1);
+
+ cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE;
+
+ if (stm32_port->fifoen)
+ cr1 |= USART_CR1_FIFOEN;
+ cr2 = 0;
+ cr3 = 0;
+
+ if (cflag & CSTOPB)
+ cr2 |= USART_CR2_STOP_2B;
+
+ if (cflag & PARENB) {
+ cr1 |= USART_CR1_PCE;
+ if ((cflag & CSIZE) == CS8) {
+ if (cfg->has_7bits_data)
+ cr1 |= USART_CR1_M0;
+ else
+ cr1 |= USART_CR1_M;
+ }
+ }
+
+ if (cflag & PARODD)
+ cr1 |= USART_CR1_PS;
+
+ port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS);
+ if (cflag & CRTSCTS) {
+ port->status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
+ cr3 |= USART_CR3_CTSE | USART_CR3_RTSE;
+ }
+
+ usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
+
+ /*
+ * The USART supports 16 or 8 times oversampling.
+ * By default we prefer 16 times oversampling, so that the receiver
+ * has a better tolerance to clock deviations.
+ * 8 times oversampling is only used to achieve higher speeds.
+ */
+ if (usartdiv < 16) {
+ oversampling = 8;
+ cr1 |= USART_CR1_OVER8;
+ stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
+ } else {
+ oversampling = 16;
+ cr1 &= ~USART_CR1_OVER8;
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
+ }
+
+ mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT;
+ fraction = usartdiv % oversampling;
+ writel_relaxed(mantissa | fraction, port->membase + ofs->brr);
+
+ uart_update_timeout(port, cflag, baud);
+
+ port->read_status_mask = USART_SR_ORE;
+ if (termios->c_iflag & INPCK)
+ port->read_status_mask |= USART_SR_PE | USART_SR_FE;
+ if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+ port->read_status_mask |= USART_SR_LBD;
+
+ /* Characters to ignore */
+ port->ignore_status_mask = 0;
+ if (termios->c_iflag & IGNPAR)
+ port->ignore_status_mask = USART_SR_PE | USART_SR_FE;
+ if (termios->c_iflag & IGNBRK) {
+ port->ignore_status_mask |= USART_SR_LBD;
+ /*
+ * If we're ignoring parity and break indicators,
+ * ignore overruns too (for real raw support).
+ */
+ if (termios->c_iflag & IGNPAR)
+ port->ignore_status_mask |= USART_SR_ORE;
+ }
+
+ /* Ignore all characters if CREAD is not set */
+ if ((termios->c_cflag & CREAD) == 0)
+ port->ignore_status_mask |= USART_SR_DUMMY_RX;
+
+ if (stm32_port->rx_ch)
+ cr3 |= USART_CR3_DMAR;
+
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ stm32_config_reg_rs485(&cr1, &cr3,
+ rs485conf->delay_rts_before_send,
+ rs485conf->delay_rts_after_send, baud);
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ cr3 &= ~USART_CR3_DEP;
+ rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
+ } else {
+ cr3 |= USART_CR3_DEP;
+ rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
+ }
+
+ } else {
+ cr3 &= ~(USART_CR3_DEM | USART_CR3_DEP);
+ cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+ }
+
+ writel_relaxed(cr3, port->membase + ofs->cr3);
+ writel_relaxed(cr2, port->membase + ofs->cr2);
+ writel_relaxed(cr1, port->membase + ofs->cr1);
+
+ stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *stm32_type(struct uart_port *port)
+{
+ return (port->type == PORT_STM32) ? DRIVER_NAME : NULL;
+}
+
+static void stm32_release_port(struct uart_port *port)
+{
+}
+
+static int stm32_request_port(struct uart_port *port)
+{
+ return 0;
+}
+
+static void stm32_config_port(struct uart_port *port, int flags)
+{
+ if (flags & UART_CONFIG_TYPE)
+ port->type = PORT_STM32;
+}
+
+static int
+stm32_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+ /* No user changeable parameters */
+ return -EINVAL;
+}
+
+static void stm32_pm(struct uart_port *port, unsigned int state,
+ unsigned int oldstate)
+{
+ struct stm32_port *stm32port = container_of(port,
+ struct stm32_port, port);
+ struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32port->info->cfg;
+ unsigned long flags = 0;
+
+ switch (state) {
+ case UART_PM_STATE_ON:
+ clk_prepare_enable(stm32port->clk);
+ break;
+ case UART_PM_STATE_OFF:
+ spin_lock_irqsave(&port->lock, flags);
+ stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ spin_unlock_irqrestore(&port->lock, flags);
+ clk_disable_unprepare(stm32port->clk);
+ break;
+ }
+}
+
+static const struct uart_ops stm32_uart_ops = {
+ .tx_empty = stm32_tx_empty,
+ .set_mctrl = stm32_set_mctrl,
+ .get_mctrl = stm32_get_mctrl,
+ .stop_tx = stm32_stop_tx,
+ .start_tx = stm32_start_tx,
+ .throttle = stm32_throttle,
+ .unthrottle = stm32_unthrottle,
+ .stop_rx = stm32_stop_rx,
+ .break_ctl = stm32_break_ctl,
+ .startup = stm32_startup,
+ .shutdown = stm32_shutdown,
+ .set_termios = stm32_set_termios,
+ .pm = stm32_pm,
+ .type = stm32_type,
+ .release_port = stm32_release_port,
+ .request_port = stm32_request_port,
+ .config_port = stm32_config_port,
+ .verify_port = stm32_verify_port,
+};
+
+static int stm32_init_port(struct stm32_port *stm32port,
+ struct platform_device *pdev)
+{
+ struct uart_port *port = &stm32port->port;
+ struct resource *res;
+ int ret;
+
+ port->iotype = UPIO_MEM;
+ port->flags = UPF_BOOT_AUTOCONF;
+ port->ops = &stm32_uart_ops;
+ port->dev = &pdev->dev;
+ port->irq = platform_get_irq(pdev, 0);
+ port->rs485_config = stm32_config_rs485;
+
+ stm32_init_rs485(port, pdev);
+
+ stm32port->wakeirq = platform_get_irq(pdev, 1);
+ stm32port->fifoen = stm32port->info->cfg.has_fifo;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ port->membase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(port->membase))
+ return PTR_ERR(port->membase);
+ port->mapbase = res->start;
+
+ spin_lock_init(&port->lock);
+
+ stm32port->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(stm32port->clk))
+ return PTR_ERR(stm32port->clk);
+
+ /* Ensure that clk rate is correct by enabling the clk */
+ ret = clk_prepare_enable(stm32port->clk);
+ if (ret)
+ return ret;
+
+ stm32port->port.uartclk = clk_get_rate(stm32port->clk);
+ if (!stm32port->port.uartclk) {
+ clk_disable_unprepare(stm32port->clk);
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ int id;
+
+ if (!np)
+ return NULL;
+
+ id = of_alias_get_id(np, "serial");
+ if (id < 0) {
+ dev_err(&pdev->dev, "failed to get alias id, errno %d\n", id);
+ return NULL;
+ }
+
+ if (WARN_ON(id >= STM32_MAX_PORTS))
+ return NULL;
+
+ stm32_ports[id].hw_flow_control = of_property_read_bool(np,
+ "st,hw-flow-ctrl");
+ stm32_ports[id].port.line = id;
+ stm32_ports[id].last_res = RX_BUF_L;
+ return &stm32_ports[id];
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id stm32_match[] = {
+ { .compatible = "st,stm32-uart", .data = &stm32f4_info},
+ { .compatible = "st,stm32f7-uart", .data = &stm32f7_info},
+ { .compatible = "st,stm32h7-uart", .data = &stm32h7_info},
+ {},
+};
+
+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 = port->mapbase + 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 = port->mapbase + 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;
+ struct stm32_port *stm32port;
+ int ret;
+
+ stm32port = stm32_of_get_stm32_port(pdev);
+ if (!stm32port)
+ return -ENODEV;
+
+ match = of_match_device(stm32_match, &pdev->dev);
+ if (match && match->data)
+ stm32port->info = (struct stm32_usart_info *)match->data;
+ else
+ return -EINVAL;
+
+ ret = stm32_init_port(stm32port, pdev);
+ if (ret)
+ return ret;
+
+ if (stm32port->info->cfg.has_wakeup && stm32port->wakeirq >= 0) {
+ ret = device_init_wakeup(&pdev->dev, true);
+ if (ret)
+ goto err_uninit;
+ }
+
+ ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
+ if (ret)
+ goto err_nowup;
+
+ 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;
+
+err_nowup:
+ if (stm32port->info->cfg.has_wakeup && stm32port->wakeirq >= 0)
+ device_init_wakeup(&pdev->dev, false);
+
+err_uninit:
+ clk_disable_unprepare(stm32port->clk);
+
+ return ret;
+}
+
+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;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+
+ 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);
+
+ if (cfg->has_wakeup && stm32_port->wakeirq >= 0)
+ device_init_wakeup(&pdev->dev, false);
+
+ clk_disable_unprepare(stm32_port->clk);
+
+ return uart_remove_one_port(&stm32_usart_driver, port);
+}
+
+
+#ifdef CONFIG_SERIAL_STM32_CONSOLE
+static void stm32_console_putchar(struct uart_port *port, int ch)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ while (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE))
+ cpu_relax();
+
+ writel_relaxed(ch, port->membase + ofs->tdr);
+}
+
+static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
+{
+ struct uart_port *port = &stm32_ports[co->index].port;
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ unsigned long flags;
+ u32 old_cr1, new_cr1;
+ int locked = 1;
+
+ local_irq_save(flags);
+ if (port->sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+ locked = spin_trylock(&port->lock);
+ else
+ spin_lock(&port->lock);
+
+ /* Save and disable interrupts, enable the transmitter */
+ old_cr1 = readl_relaxed(port->membase + ofs->cr1);
+ new_cr1 = old_cr1 & ~USART_CR1_IE_MASK;
+ new_cr1 |= USART_CR1_TE | BIT(cfg->uart_enable_bit);
+ writel_relaxed(new_cr1, port->membase + ofs->cr1);
+
+ uart_console_write(port, s, cnt, stm32_console_putchar);
+
+ /* Restore interrupt state */
+ writel_relaxed(old_cr1, port->membase + ofs->cr1);
+
+ if (locked)
+ spin_unlock(&port->lock);
+ local_irq_restore(flags);
+}
+
+static int stm32_console_setup(struct console *co, char *options)
+{
+ struct stm32_port *stm32port;
+ int baud = 9600;
+ int bits = 8;
+ int parity = 'n';
+ int flow = 'n';
+
+ if (co->index >= STM32_MAX_PORTS)
+ return -ENODEV;
+
+ stm32port = &stm32_ports[co->index];
+
+ /*
+ * This driver does not support early console initialization
+ * (use ARM early printk support instead), so we only expect
+ * this to be called during the uart port registration when the
+ * driver gets probed and the port should be mapped at that point.
+ */
+ if (stm32port->port.mapbase == 0 || stm32port->port.membase == NULL)
+ return -ENXIO;
+
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+ return uart_set_options(&stm32port->port, co, baud, parity, bits, flow);
+}
+
+static struct console stm32_console = {
+ .name = STM32_SERIAL_NAME,
+ .device = uart_console_device,
+ .write = stm32_console_write,
+ .setup = stm32_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+ .data = &stm32_usart_driver,
+};
+
+#define STM32_SERIAL_CONSOLE (&stm32_console)
+
+#else
+#define STM32_SERIAL_CONSOLE NULL
+#endif /* CONFIG_SERIAL_STM32_CONSOLE */
+
+static struct uart_driver stm32_usart_driver = {
+ .driver_name = DRIVER_NAME,
+ .dev_name = STM32_SERIAL_NAME,
+ .major = 0,
+ .minor = 0,
+ .nr = STM32_MAX_PORTS,
+ .cons = STM32_SERIAL_CONSOLE,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static void stm32_serial_enable_wakeup(struct uart_port *port, bool enable)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ u32 val;
+
+ if (!cfg->has_wakeup || stm32_port->wakeirq < 0)
+ return;
+
+ if (enable) {
+ stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ stm32_set_bits(port, ofs->cr1, USART_CR1_UESM);
+ val = readl_relaxed(port->membase + ofs->cr3);
+ val &= ~USART_CR3_WUS_MASK;
+ /* Enable Wake up interrupt from low power on start bit */
+ val |= USART_CR3_WUS_START_BIT | USART_CR3_WUFIE;
+ writel_relaxed(val, port->membase + ofs->cr3);
+ stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ } else {
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_UESM);
+ }
+}
+
+static int stm32_serial_suspend(struct device *dev)
+{
+ struct uart_port *port = dev_get_drvdata(dev);
+
+ uart_suspend_port(&stm32_usart_driver, port);
+
+ if (device_may_wakeup(dev))
+ stm32_serial_enable_wakeup(port, true);
+ else
+ stm32_serial_enable_wakeup(port, false);
+
+ return 0;
+}
+
+static int stm32_serial_resume(struct device *dev)
+{
+ struct uart_port *port = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ stm32_serial_enable_wakeup(port, false);
+
+ return uart_resume_port(&stm32_usart_driver, port);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops stm32_serial_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(stm32_serial_suspend, stm32_serial_resume)
+};
+
+static struct platform_driver stm32_serial_driver = {
+ .probe = stm32_serial_probe,
+ .remove = stm32_serial_remove,
+ .driver = {
+ .name = DRIVER_NAME,
+ .pm = &stm32_serial_pm_ops,
+ .of_match_table = of_match_ptr(stm32_match),
+ },
+};
+
+static int __init usart_init(void)
+{
+ static char banner[] __initdata = "STM32 USART driver initialized";
+ int ret;
+
+ pr_info("%s\n", banner);
+
+ ret = uart_register_driver(&stm32_usart_driver);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&stm32_serial_driver);
+ if (ret)
+ uart_unregister_driver(&stm32_usart_driver);
+
+ return ret;
+}
+
+static void __exit usart_exit(void)
+{
+ platform_driver_unregister(&stm32_serial_driver);
+ uart_unregister_driver(&stm32_usart_driver);
+}
+
+module_init(usart_init);
+module_exit(usart_exit);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 serial port driver");
+MODULE_LICENSE("GPL v2");