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-rw-r--r--drivers/tty/serial/8250/8250.h25
-rw-r--r--drivers/tty/serial/8250/8250_dw.c163
-rw-r--r--drivers/tty/serial/8250/8250_port.c28
3 files changed, 161 insertions, 55 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 8caecfc85d93..77fe0588fd6b 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -175,7 +175,9 @@ static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
return value;
}
+void serial8250_clear_fifos(struct uart_8250_port *p);
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
+void serial8250_fifo_wait_for_lsr_thre(struct uart_8250_port *up, unsigned int count);
void serial8250_rpm_get(struct uart_8250_port *p);
void serial8250_rpm_put(struct uart_8250_port *p);
@@ -400,6 +402,26 @@ static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
return dma && dma->tx_running;
}
+
+static inline void serial8250_tx_dma_pause(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+
+ if (!dma->tx_running)
+ return;
+
+ dmaengine_pause(dma->txchan);
+}
+
+static inline void serial8250_tx_dma_resume(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+
+ if (!dma->tx_running)
+ return;
+
+ dmaengine_resume(dma->txchan);
+}
#else
static inline int serial8250_tx_dma(struct uart_8250_port *p)
{
@@ -421,6 +443,9 @@ static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
{
return false;
}
+
+static inline void serial8250_tx_dma_pause(struct uart_8250_port *p) { }
+static inline void serial8250_tx_dma_resume(struct uart_8250_port *p) { }
#endif
static inline int ns16550a_goto_highspeed(struct uart_8250_port *up)
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 3d8032f752b8..94beadb4024d 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -16,6 +16,7 @@
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/io.h>
+#include <linux/lockdep.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/notifier.h>
@@ -47,6 +48,8 @@
#define DW_UART_MCR_SIRE BIT(6)
+#define DW_UART_USR_BUSY BIT(0)
+
/* Renesas specific register fields */
#define RZN1_UART_xDMACR_DMA_EN BIT(0)
#define RZN1_UART_xDMACR_1_WORD_BURST (0 << 1)
@@ -89,6 +92,7 @@ struct dw8250_data {
unsigned int skip_autocfg:1;
unsigned int uart_16550_compatible:1;
+ unsigned int in_idle:1;
u8 no_int_count;
};
@@ -121,78 +125,151 @@ static inline u32 dw8250_modify_msr(struct uart_port *p, unsigned int offset, u3
return value;
}
+static void dw8250_idle_exit(struct uart_port *p)
+{
+ struct dw8250_data *d = to_dw8250_data(p->private_data);
+ struct uart_8250_port *up = up_to_u8250p(p);
+
+ if (d->uart_16550_compatible)
+ return;
+
+ if (up->capabilities & UART_CAP_FIFO)
+ serial_port_out(p, UART_FCR, up->fcr);
+ serial_port_out(p, UART_MCR, up->mcr);
+ serial_port_out(p, UART_IER, up->ier);
+
+ /* DMA Rx is restarted by IRQ handler as needed. */
+ if (up->dma)
+ serial8250_tx_dma_resume(up);
+
+ d->in_idle = 0;
+}
+
/*
- * This function is being called as part of the uart_port::serial_out()
- * routine. Hence, it must not call serial_port_out() or serial_out()
- * against the modified registers here, i.e. LCR.
+ * Ensure BUSY is not asserted. If DW UART is configured with
+ * !uart_16550_compatible, the writes to LCR, DLL, and DLH fail while
+ * BUSY is asserted.
+ *
+ * Context: port's lock must be held
*/
-static void dw8250_force_idle(struct uart_port *p)
+static int dw8250_idle_enter(struct uart_port *p)
{
+ struct dw8250_data *d = to_dw8250_data(p->private_data);
+ unsigned int usr_reg = d->pdata ? d->pdata->usr_reg : DW_UART_USR;
struct uart_8250_port *up = up_to_u8250p(p);
- unsigned int lsr;
+ int retries;
+ u32 lsr;
- /*
- * The following call currently performs serial_out()
- * against the FCR register. Because it differs to LCR
- * there will be no infinite loop, but if it ever gets
- * modified, we might need a new custom version of it
- * that avoids infinite recursion.
- */
- serial8250_clear_and_reinit_fifos(up);
+ lockdep_assert_held_once(&p->lock);
+
+ if (d->uart_16550_compatible)
+ return 0;
+
+ d->in_idle = 1;
+
+ /* Prevent triggering interrupt from RBR filling */
+ serial_port_out(p, UART_IER, 0);
+
+ if (up->dma) {
+ serial8250_rx_dma_flush(up);
+ if (serial8250_tx_dma_running(up))
+ serial8250_tx_dma_pause(up);
+ }
/*
- * With PSLVERR_RESP_EN parameter set to 1, the device generates an
- * error response when an attempt to read an empty RBR with FIFO
- * enabled.
+ * Wait until Tx becomes empty + one extra frame time to ensure all bits
+ * have been sent on the wire.
+ *
+ * FIXME: frame_time delay is too long with very low baudrates.
*/
- if (up->fcr & UART_FCR_ENABLE_FIFO) {
- lsr = serial_port_in(p, UART_LSR);
- if (!(lsr & UART_LSR_DR))
- return;
+ serial8250_fifo_wait_for_lsr_thre(up, p->fifosize);
+ ndelay(p->frame_time);
+
+ serial_port_out(p, UART_MCR, up->mcr | UART_MCR_LOOP);
+
+ retries = 4; /* Arbitrary limit, 2 was always enough in tests */
+ do {
+ serial8250_clear_fifos(up);
+ if (!(serial_port_in(p, usr_reg) & DW_UART_USR_BUSY))
+ break;
+ /* FIXME: frame_time delay is too long with very low baudrates. */
+ ndelay(p->frame_time);
+ } while (--retries);
+
+ lsr = serial_lsr_in(up);
+ if (lsr & UART_LSR_DR) {
+ serial_port_in(p, UART_RX);
+ up->lsr_saved_flags = 0;
}
- serial_port_in(p, UART_RX);
+ /* Now guaranteed to have BUSY deasserted? Just sanity check */
+ if (serial_port_in(p, usr_reg) & DW_UART_USR_BUSY) {
+ dw8250_idle_exit(p);
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
+static void dw8250_set_divisor(struct uart_port *p, unsigned int baud,
+ unsigned int quot, unsigned int quot_frac)
+{
+ struct uart_8250_port *up = up_to_u8250p(p);
+ int ret;
+
+ ret = dw8250_idle_enter(p);
+ if (ret < 0)
+ return;
+
+ serial_port_out(p, UART_LCR, up->lcr | UART_LCR_DLAB);
+ if (!(serial_port_in(p, UART_LCR) & UART_LCR_DLAB))
+ goto idle_failed;
+
+ serial_dl_write(up, quot);
+ serial_port_out(p, UART_LCR, up->lcr);
+
+idle_failed:
+ dw8250_idle_exit(p);
}
/*
* This function is being called as part of the uart_port::serial_out()
- * routine. Hence, it must not call serial_port_out() or serial_out()
- * against the modified registers here, i.e. LCR.
+ * routine. Hence, special care must be taken when serial_port_out() or
+ * serial_out() against the modified registers here, i.e. LCR (d->in_idle is
+ * used to break recursion loop).
*/
static void dw8250_check_lcr(struct uart_port *p, unsigned int offset, u32 value)
{
struct dw8250_data *d = to_dw8250_data(p->private_data);
- void __iomem *addr = p->membase + (offset << p->regshift);
- int tries = 1000;
+ u32 lcr;
+ int ret;
if (offset != UART_LCR || d->uart_16550_compatible)
return;
+ lcr = serial_port_in(p, UART_LCR);
+
/* Make sure LCR write wasn't ignored */
- while (tries--) {
- u32 lcr = serial_port_in(p, offset);
+ if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
+ return;
- if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
- return;
+ if (d->in_idle)
+ goto write_err;
- dw8250_force_idle(p);
+ ret = dw8250_idle_enter(p);
+ if (ret < 0)
+ goto write_err;
-#ifdef CONFIG_64BIT
- if (p->type == PORT_OCTEON)
- __raw_writeq(value & 0xff, addr);
- else
-#endif
- if (p->iotype == UPIO_MEM32)
- writel(value, addr);
- else if (p->iotype == UPIO_MEM32BE)
- iowrite32be(value, addr);
- else
- writeb(value, addr);
- }
+ serial_port_out(p, UART_LCR, value);
+ dw8250_idle_exit(p);
+ return;
+
+write_err:
/*
* FIXME: this deadlocks if port->lock is already held
* dev_err(p->dev, "Couldn't set LCR to %d\n", value);
*/
+ return; /* Silences "label at the end of compound statement" */
}
/*
@@ -632,8 +709,10 @@ static int dw8250_probe(struct platform_device *pdev)
p->type = PORT_8250;
p->flags = UPF_FIXED_PORT;
p->dev = dev;
+
p->set_ldisc = dw8250_set_ldisc;
p->set_termios = dw8250_set_termios;
+ p->set_divisor = dw8250_set_divisor;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 94a64b3dd1f7..328711b5df1a 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -489,7 +489,7 @@ serial_port_out_sync(struct uart_port *p, int offset, int value)
/*
* FIFO support.
*/
-static void serial8250_clear_fifos(struct uart_8250_port *p)
+void serial8250_clear_fifos(struct uart_8250_port *p)
{
if (p->capabilities & UART_CAP_FIFO) {
serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO);
@@ -498,6 +498,7 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
serial_out(p, UART_FCR, 0);
}
}
+EXPORT_SYMBOL_NS_GPL(serial8250_clear_fifos, "SERIAL_8250");
static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
@@ -3198,6 +3199,17 @@ void serial8250_set_defaults(struct uart_8250_port *up)
}
EXPORT_SYMBOL_GPL(serial8250_set_defaults);
+void serial8250_fifo_wait_for_lsr_thre(struct uart_8250_port *up, unsigned int count)
+{
+ unsigned int i;
+
+ for (i = 0; i < count; i++) {
+ if (wait_for_lsr(up, UART_LSR_THRE))
+ return;
+ }
+}
+EXPORT_SYMBOL_NS_GPL(serial8250_fifo_wait_for_lsr_thre, "SERIAL_8250");
+
#ifdef CONFIG_SERIAL_8250_CONSOLE
static void serial8250_console_putchar(struct uart_port *port, unsigned char ch)
@@ -3239,16 +3251,6 @@ static void serial8250_console_restore(struct uart_8250_port *up)
serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS);
}
-static void fifo_wait_for_lsr(struct uart_8250_port *up, unsigned int count)
-{
- unsigned int i;
-
- for (i = 0; i < count; i++) {
- if (wait_for_lsr(up, UART_LSR_THRE))
- return;
- }
-}
-
/*
* Print a string to the serial port using the device FIFO
*
@@ -3267,7 +3269,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
while (s != end) {
/* Allow timeout for each byte of a possibly full FIFO */
- fifo_wait_for_lsr(up, fifosize);
+ serial8250_fifo_wait_for_lsr_thre(up, fifosize);
for (i = 0; i < fifosize && s != end; ++i) {
if (*s == '\n' && !cr_sent) {
@@ -3285,7 +3287,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
* Allow timeout for each byte written since the caller will only wait
* for UART_LSR_BOTH_EMPTY using the timeout of a single character
*/
- fifo_wait_for_lsr(up, tx_count);
+ serial8250_fifo_wait_for_lsr_thre(up, tx_count);
}
/*
generated by cgit v1.2.3 (git 2.0.4) at 2026-06-05 05:29:27 +0000