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 <gerald.baeza@xxxxxx>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@xxxxxx>
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 520e7de..24c4d82 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -11,26 +11,31 @@
#define SUPPORT_SYSRQ
#endif
-#include <linux/module.h>
-#include <linux/serial.h>
+#include <linux/clk.h>
#include <linux/console.h>
-#include <linux/sysrq.h>
-#include <linux/platform_device.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/tty.h>
-#include <linux/tty_flip.h>
-#include <linux/delay.h>
-#include <linux/spinlock.h>
-#include <linux/pm_runtime.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/clk.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)
{
@@ -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 75f8388..41d9749 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;
};
--
1.9.1
--
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