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tty: serial: owl: Add support for kernel debugger

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Implement 'poll_put_char' and 'poll_get_char' callbacks in struct
'owl_uart_ops' that enables OWL UART to be used for kernel debugging
over serial line.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Link: https://lore.kernel.org/r/026543195b9aeefb339d90abc5660a6ac7463c63.1610484108.git.cristian.ciocaltea@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Cristian Ciocaltea 2021-01-12 22:55:38 +02:00 committed by Greg Kroah-Hartman
parent c9cd57bf57
commit 9335e23ddc
1 changed files with 38 additions and 0 deletions
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38
drivers/tty/serial/owl-uart.c
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@ -12,6 +12,7 @@
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
@ -62,6 +63,9 @@
#define OWL_UART_STAT_TRFL_MASK GENMASK(16, 11)
#define OWL_UART_STAT_UTBB BIT(17)
#define OWL_UART_POLL_USEC 5
#define OWL_UART_TIMEOUT_USEC 10000
static struct uart_driver owl_uart_driver;
struct owl_uart_info {
@ -461,6 +465,36 @@ static void owl_uart_config_port(struct uart_port *port, int flags)
}
}
#ifdef CONFIG_CONSOLE_POLL
static int owl_uart_poll_get_char(struct uart_port *port)
{
if (owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_RFEM)
return NO_POLL_CHAR;
return owl_uart_read(port, OWL_UART_RXDAT);
}
static void owl_uart_poll_put_char(struct uart_port *port, unsigned char ch)
{
u32 reg;
int ret;
/* Wait while FIFO is full or timeout */
ret = readl_poll_timeout_atomic(port->membase + OWL_UART_STAT, reg,
!(reg & OWL_UART_STAT_TFFU),
OWL_UART_POLL_USEC,
OWL_UART_TIMEOUT_USEC);
if (ret == -ETIMEDOUT) {
dev_err(port->dev, "Timeout waiting while UART TX FULL\n");
return;
}
owl_uart_write(port, ch, OWL_UART_TXDAT);
}
#endif /* CONFIG_CONSOLE_POLL */
static const struct uart_ops owl_uart_ops = {
.set_mctrl = owl_uart_set_mctrl,
.get_mctrl = owl_uart_get_mctrl,
@ -476,6 +510,10 @@ static const struct uart_ops owl_uart_ops = {
.request_port = owl_uart_request_port,
.release_port = owl_uart_release_port,
.verify_port = owl_uart_verify_port,
#ifdef CONFIG_CONSOLE_POLL
.poll_get_char = owl_uart_poll_get_char,
.poll_put_char = owl_uart_poll_put_char,
#endif
};
#ifdef CONFIG_SERIAL_OWL_CONSOLE