@@ -263,6 +263,7 @@ struct uart_amba_port {
char type[12];
bool rs485_tx_started;
unsigned int rs485_tx_drain_interval; /* usecs */
+ bool console_line_ended;
#ifdef CONFIG_DMA_ENGINE
/* DMA stuff */
unsigned int dmacr; /* dma control reg */
@@ -2305,50 +2306,7 @@ static void pl011_console_putchar(struct uart_port *port, unsigned char ch)
while (pl011_read(uap, REG_FR) & UART01x_FR_TXFF)
cpu_relax();
pl011_write(ch, uap, REG_DR);
-}
-
-static void
-pl011_console_write(struct console *co, const char *s, unsigned int count)
-{
- struct uart_amba_port *uap = amba_ports[co->index];
- unsigned int old_cr = 0, new_cr;
- unsigned long flags;
- int locked = 1;
-
- clk_enable(uap->clk);
-
- if (oops_in_progress)
- locked = uart_port_trylock_irqsave(&uap->port, &flags);
- else
- uart_port_lock_irqsave(&uap->port, &flags);
-
- /*
- * First save the CR then disable the interrupts
- */
- if (!uap->vendor->always_enabled) {
- old_cr = pl011_read(uap, REG_CR);
- new_cr = old_cr & ~UART011_CR_CTSEN;
- new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
- pl011_write(new_cr, uap, REG_CR);
- }
-
- uart_console_write(&uap->port, s, count, pl011_console_putchar);
-
- /*
- * Finally, wait for transmitter to become empty and restore the
- * TCR. Allow feature register bits to be inverted to work around
- * errata.
- */
- while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr)
- & uap->vendor->fr_busy)
- cpu_relax();
- if (!uap->vendor->always_enabled)
- pl011_write(old_cr, uap, REG_CR);
-
- if (locked)
- uart_port_unlock_irqrestore(&uap->port, flags);
-
- clk_disable(uap->clk);
+ uap->console_line_ended = (ch == '\n');
}
static void pl011_console_get_options(struct uart_amba_port *uap, int *baud,
@@ -2411,6 +2369,8 @@ static int pl011_console_setup(struct console *co, char *options)
if (ret)
return ret;
+ uap->console_line_ended = true;
+
if (dev_get_platdata(uap->port.dev)) {
struct amba_pl011_data *plat;
@@ -2494,14 +2454,105 @@ static int pl011_console_match(struct console *co, char *name, int idx,
return -ENODEV;
}
+static void
+pl011_console_write_atomic(struct console *co, struct nbcon_write_context *wctxt)
+{
+ struct uart_amba_port *uap = amba_ports[co->index];
+ unsigned int old_cr = 0;
+
+ if (!nbcon_enter_unsafe(wctxt))
+ return;
+
+ clk_enable(uap->clk);
+
+ if (!uap->vendor->always_enabled) {
+ old_cr = pl011_read(uap, REG_CR);
+ pl011_write((old_cr & ~UART011_CR_CTSEN) | (UART01x_CR_UARTEN | UART011_CR_TXE),
+ uap, REG_CR);
+ }
+
+ if (!uap->console_line_ended)
+ uart_console_write(&uap->port, "\n", 1, pl011_console_putchar);
+ uart_console_write(&uap->port, wctxt->outbuf, wctxt->len, pl011_console_putchar);
+
+ while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr) & uap->vendor->fr_busy)
+ cpu_relax();
+
+ if (!uap->vendor->always_enabled)
+ pl011_write(old_cr, uap, REG_CR);
+
+ clk_disable(uap->clk);
+
+ nbcon_exit_unsafe(wctxt);
+}
+
+static void
+pl011_console_write_thread(struct console *co, struct nbcon_write_context *wctxt)
+{
+ struct uart_amba_port *uap = amba_ports[co->index];
+ unsigned int old_cr = 0;
+
+ if (!nbcon_enter_unsafe(wctxt))
+ return;
+
+ clk_enable(uap->clk);
+
+ if (!uap->vendor->always_enabled) {
+ old_cr = pl011_read(uap, REG_CR);
+ pl011_write((old_cr & ~UART011_CR_CTSEN) | (UART01x_CR_UARTEN | UART011_CR_TXE),
+ uap, REG_CR);
+ }
+
+ if (nbcon_exit_unsafe(wctxt)) {
+ int i;
+ unsigned int len = READ_ONCE(wctxt->len);
+
+ for (i = 0; i < len; i++) {
+ if (!nbcon_enter_unsafe(wctxt))
+ break;
+ uart_console_write(&uap->port, wctxt->outbuf + i, 1, pl011_console_putchar);
+ if (!nbcon_exit_unsafe(wctxt))
+ break;
+ }
+ }
+
+ while (!nbcon_enter_unsafe(wctxt))
+ nbcon_reacquire_nobuf(wctxt);
+
+ while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr) & uap->vendor->fr_busy)
+ cpu_relax();
+
+ if (!uap->vendor->always_enabled)
+ pl011_write(old_cr, uap, REG_CR);
+
+ clk_disable(uap->clk);
+
+ nbcon_exit_unsafe(wctxt);
+}
+
+static void
+pl011_console_device_lock(struct console *co, unsigned long *flags)
+{
+ __uart_port_lock_irqsave(&amba_ports[co->index]->port, flags);
+}
+
+static void
+pl011_console_device_unlock(struct console *co, unsigned long flags)
+{
+ __uart_port_unlock_irqrestore(&amba_ports[co->index]->port, flags);
+}
+
static struct uart_driver amba_reg;
static struct console amba_console = {
.name = "ttyAMA",
- .write = pl011_console_write,
.device = uart_console_device,
.setup = pl011_console_setup,
.match = pl011_console_match,
- .flags = CON_PRINTBUFFER | CON_ANYTIME,
+ .write_atomic = pl011_console_write_atomic,
+ .write_thread = pl011_console_write_thread,
+ .device_lock = pl011_console_device_lock,
+ .device_unlock = pl011_console_device_unlock,
+ .flags = CON_PRINTBUFFER | CON_ANYTIME | CON_NBCON,
.index = -1,
.data = &amba_reg,
};
Implement the callbacks required for an NBCON console [0] on the amba-pl011 console driver. Referred to the NBCON implementation work for 8250 [1] and imx [2]. The normal-priority write_thread checks for console ownership each time a character is printed. write_atomic holds the console ownership until the entire string is printed. UART register operations are protected from other contexts by uart_port_lock, except for a final flush(nbcon_atomic_flush_unsafe) on panic. The patch has been verified to correctly handle the output and competition of messages with different priorities and flushing panic message to console after nmi panic using ARM64 QEMU and a physical machine(A64FX). [0] https://lore.kernel.org/all/ZuRRTbapH0DCj334@pathway.suse.cz/ [1] https://lore.kernel.org/all/20240913140538.221708-1-john.ogness@linutronix.de/T/ [2] https://lore.kernel.org/linux-arm-kernel/20240913-serial-imx-nbcon-v3-1-4c627302335b@geanix.com/T/ Signed-off-by: Toshiyuki Sato <fj6611ie@aa.jp.fujitsu.com> --- This patch removes the legacy console code. Please comment if you have any concerns. I plan to try a stress test, referencing the work for 8250. https://lore.kernel.org/lkml/ZsdoD6PomBRsB-ow@debarbos-thinkpadt14sgen2i.remote.csb/#t Changes in v2: - Remove the module parameter used to switch between legacy and nbcon. - Remove codes for legacy console. - Fix build errors detected by the test robot. - based on 6.13-rc7 v1: https://lore.kernel.org/all/20250108004730.2302996-1-fj6611ie@aa.jp.fujitsu.com/ Thanks Greg for the advice & comment. --- drivers/tty/serial/amba-pl011.c | 143 ++++++++++++++++++++++---------- 1 file changed, 97 insertions(+), 46 deletions(-)