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linux-sg2042/drivers/tty/serial/stm32-usart.c

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/*
* Copyright (C) Maxime Coquelin 2015
* Authors: Maxime Coquelin <mcoquelin.stm32@gmail.com>
* Gerald Baeza <gerald.baeza@st.com>
* License terms: GNU General Public License (GPL), version 2
*
* 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/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 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;
static int last_res = RX_BUF_L;
if (port->irq_wake)
pm_wakeup_event(tport->tty->dev, 0);
while (stm32_pending_rx(port, &sr, &last_res, threaded)) {
sr |= USART_SR_DUMMY_RX;
c = stm32_get_char(port, &sr, &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, 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);
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_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;
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;
val = USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
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);
stm32_clr_bits(port, ofs->cr1, val);
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;
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;
cr1 |= BIT(cfg->uart_enable_bit);
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;
}
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;
stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
} else {
oversampling = 16;
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;
writel_relaxed(cr3, port->membase + ofs->cr3);
writel_relaxed(cr2, port->membase + ofs->cr2);
writel_relaxed(cr1, port->membase + ofs->cr1);
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);
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)
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)
id = 0;
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;
return &stm32_ports[id];
}
#ifdef CONFIG_OF
static const struct of_device_id stm32_match[] = {
{ .compatible = "st,stm32-usart", .data = &stm32f4_info},
{ .compatible = "st,stm32-uart", .data = &stm32f4_info},
{ .compatible = "st,stm32f7-usart", .data = &stm32f7_info},
{ .compatible = "st,stm32f7-uart", .data = &stm32f7_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;
ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
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;
}
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);
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,
};
static struct platform_driver stm32_serial_driver = {
.probe = stm32_serial_probe,
.remove = stm32_serial_remove,
.driver = {
.name = DRIVER_NAME,
.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");
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