tty: serial: Add Actions Semi Owl UART earlycon

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

Based on LeMaker linux-actions tree.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 15f79c27748df1611b1643b77ca68e2a5e7cfaab..38496249f8ba640524cd137fe26669aabe73a3a4 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -945,6 +945,12 @@
                        must already be setup and configured. Options are not
                        yet supported.
 
+               owl,<addr>
+                       Start an early, polled-mode console on a serial port
+                       of an Actions Semi SoC, such as S500 or S900, at the
+                       specified address. The serial port must already be
+                       setup and configured. Options are not yet supported.
+
                smh     Use ARM semihosting calls for early console.
 
                s3c2410,<addr>

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 07812a7ea2a4029c5bd8cff01cab4680f0d9c743..1f096e2bb398c07f5d420494c2e441ca8aecfb3b 100644 (file)
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1688,6 +1688,25 @@ 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_ACTIONS || COMPILE_TEST
+       select SERIAL_CORE
+       help
+         This driver is for Actions Semiconductor 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 Semiconductor S500/S900 UART
+         as the system console. Only earlycon is implemented currently.
+
 endmenu
 
 config SERIAL_MCTRL_GPIO

diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 53c03e005132105a6735e17fcbb132ca6d9582dc..fe88a75d9a59cff23fe8c4c20544a9a3f146a94d 100644 (file)
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -92,6 +92,7 @@ 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 (file)
index 0000000..1b80087
--- /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 Färber
+ *
+ * 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           BIT(14)
+#define OWL_UART_CTL_EN                        BIT(15)
+#define OWL_UART_CTL_RXIE              BIT(18)
+#define OWL_UART_CTL_TXIE              BIT(19)
+
+#define OWL_UART_STAT_RIP              BIT(0)
+#define OWL_UART_STAT_TIP              BIT(1)
+#define OWL_UART_STAT_TFFU             BIT(6)
+#define OWL_UART_STAT_TRFL_MASK                (0x1f << 11)
+#define OWL_UART_STAT_UTBB             BIT(17)
+
+static inline void owl_uart_write(struct uart_port *port, u32 val, unsigned int off)
+{
+       writel(val, port->membase + off);
+}
+
+static inline u32 owl_uart_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_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU)
+               cpu_relax();
+
+       owl_uart_write(port, ch, OWL_UART_TXDAT);
+}
+
+static void owl_uart_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_uart_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_uart_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_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TRFL_MASK)
+               cpu_relax();
+
+       /* clear IRQ pending */
+       val = owl_uart_read(port, OWL_UART_STAT);
+       val |= OWL_UART_STAT_TIP | OWL_UART_STAT_RIP;
+       owl_uart_write(port, val, OWL_UART_STAT);
+
+       owl_uart_write(port, old_ctl, OWL_UART_CTL);
+
+       if (locked)
+               spin_unlock(&port->lock);
+
+       local_irq_restore(flags);
+}
+
+static void owl_uart_early_console_write(struct console *co,
+                                        const char *s,
+                                        u_int count)
+{
+       struct earlycon_device *dev = co->data;
+
+       owl_uart_port_write(&dev->port, s, count);
+}
+
+static int __init
+owl_uart_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+       if (!device->port.membase)
+               return -ENODEV;
+
+       device->con->write = owl_uart_early_console_write;
+
+       return 0;
+}
+OF_EARLYCON_DECLARE(owl, "actions,owl-uart",
+                   owl_uart_early_console_setup);
+
+#endif /* CONFIG_SERIAL_OWL_CONSOLE */