[PATCH 06/11] tty: serial: Add Actions Semi Owl UART earlycon

Andreas Färber
2017-02-15T16:55:23Z

This implements an earlycon for Actions Semi S500/S900 SoCs.

Based on LeMaker linux-actions tree.

Signed-off-by: Andreas F?rber <afaerber@suse.de>
---
drivers/tty/serial/Kconfig | 19 ++++++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/owl-uart.c | 135 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 155 insertions(+)
create mode 100644 drivers/tty/serial/owl-uart.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 6117ac8..9d4213c 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1677,6 +1677,25 @@ config SERIAL_MVEBU_CONSOLE
and warnings and which allows logins in single user mode)
Otherwise, say 'N'.

+config SERIAL_OWL
+ bool "Actions Semi Owl serial port support"
+ depends on ARCH_OWL || COMPILE_TEST
+ select SERIAL_CORE
+ help
+ This driver is for Actions Semi S500/S900 SoC's UART.
+ Say 'Y' here if you wish to use the on-board serial port.
+ Otherwise, say 'N'.
+
+config SERIAL_OWL_CONSOLE
+ bool "Console on Actions Semi Owl serial port"
+ depends on SERIAL_OWL=y
+ select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
+ default y
+ help
+ Say 'Y' here if you wish to use Actions Semi S500/S900 UART as the
+ system console.
+
endmenu

config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 2d6288b..91f3571 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -91,6 +91,7 @@ obj-$(CONFIG_SERIAL_STM32) += stm32-usart.o
obj-$(CONFIG_SERIAL_MVEBU_UART) += mvebu-uart.o
obj-$(CONFIG_SERIAL_PIC32) += pic32_uart.o
obj-$(CONFIG_SERIAL_MPS2_UART) += mps2-uart.o
+obj-$(CONFIG_SERIAL_OWL) += owl-uart.o

# GPIOLIB helpers for modem control lines
obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
new file mode 100644
index 0000000..f8b1bb6
--- /dev/null
+++ b/drivers/tty/serial/owl-uart.c
@@ -0,0 +1,135 @@
+/*
+ * Actions Semi Owl family serial console
+ *
+ * Copyright 2013 Actions Semi Inc.
+ * Author: Actions Semi, Inc.
+ *
+ * Copyright (c) 2016-2017 Andreas F?rber
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+
+#define OWL_UART_CTL 0x000
+#define OWL_UART_TXDAT 0x008
+#define OWL_UART_STAT 0x00c
+
+#define OWL_UART_CTL_TRFS_TX (1 << 14)
+#define OWL_UART_CTL_EN (1 << 15)
+#define OWL_UART_CTL_RXIE (1 << 18)
+#define OWL_UART_CTL_TXIE (1 << 19)
+
+#define OWL_UART_STAT_RIP (1 << 0)
+#define OWL_UART_STAT_TIP (1 << 1)
+#define OWL_UART_STAT_TFFU (1 << 6)
+#define OWL_UART_STAT_TRFL_MASK (0x1f << 11)
+#define OWL_UART_STAT_UTBB (1 << 17)
+
+static inline void owl_serial_write(struct uart_port *port, u32 val, unsigned int off)
+{
+ writel(val, port->membase + off);
+}
+
+static inline u32 owl_serial_read(struct uart_port *port, unsigned int off)
+{
+ return readl(port->membase + off);
+}
+
+#ifdef CONFIG_SERIAL_OWL_CONSOLE
+
+static void owl_console_putchar(struct uart_port *port, int ch)
+{
+ if (!port->membase)
+ return;
+
+ while (owl_serial_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU)
+ cpu_relax();
+
+ owl_serial_write(port, ch, OWL_UART_TXDAT);
+}
+
+static void owl_serial_port_write(struct uart_port *port, const char *s,
+ u_int count)
+{
+ u32 old_ctl, val;
+ unsigned long flags;
+ int locked;
+
+ local_irq_save(flags);
+
+ if (port->sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+ locked = spin_trylock(&port->lock);
+ else {
+ spin_lock(&port->lock);
+ locked = 1;
+ }
+
+ old_ctl = owl_serial_read(port, OWL_UART_CTL);
+ val = old_ctl | OWL_UART_CTL_TRFS_TX;
+ /* disable IRQ */
+ val &= ~(OWL_UART_CTL_RXIE | OWL_UART_CTL_TXIE);
+ owl_serial_write(port, val, OWL_UART_CTL);
+
+ uart_console_write(port, s, count, owl_console_putchar);
+
+ /* wait until all contents have been sent out */
+ while (owl_serial_read(port, OWL_UART_STAT) & OWL_UART_STAT_TRFL_MASK)
+ cpu_relax();
+
+ /* clear IRQ pending */
+ val = owl_serial_read(port, OWL_UART_STAT);
+ val |= OWL_UART_STAT_TIP | OWL_UART_STAT_RIP;
+ owl_serial_write(port, val, OWL_UART_STAT);
+
+ owl_serial_write(port, old_ctl, OWL_UART_CTL);
+
+ if (locked)
+ spin_unlock(&port->lock);
+
+ local_irq_restore(flags);
+}
+
+static void owl_serial_early_console_write(struct console *co,
+ const char *s,
+ u_int count)
+{
+ struct earlycon_device *dev = co->data;
+
+ owl_serial_port_write(&dev->port, s, count);
+}
+
+static int __init
+owl_serial_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = owl_serial_early_console_write;
+
+ return 0;
+}
+OF_EARLYCON_DECLARE(owl, "acts,owl-uart",
+ owl_serial_early_console_setup);
+
+#endif /* CONFIG_SERIAL_OWL_CONSOLE */
--
2.10.2