[PATCH 5/6] tty: serial: Add RDA Micro UART driver
Andreas Färber
afaerber at suse.de
Mon Jun 26 17:55:19 PDT 2017
Add "rda" earlycon driver for RDA8810PL UART.
Signed-off-by: Andreas Färber <afaerber at suse.de>
---
Documentation/admin-guide/kernel-parameters.txt | 6 ++
drivers/tty/serial/Kconfig | 19 ++++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/rda-uart.c | 117 ++++++++++++++++++++++++
4 files changed, 143 insertions(+)
create mode 100644 drivers/tty/serial/rda-uart.c
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0e2091c6fa6b..c97f8b64b3f1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -967,6 +967,12 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
+ rda,<addr>
+ Start an early, polled-mode console on a serial port
+ of an RDA Micro SoC, such as RDA8810PL, 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 1f096e2bb398..25e106a62e06 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1707,6 +1707,25 @@ config SERIAL_OWL_CONSOLE
Say 'Y' here if you wish to use Actions Semiconductor S500/S900 UART
as the system console. Only earlycon is implemented currently.
+config SERIAL_RDA
+ bool "RDA Micro serial port support"
+ depends on ARCH_RDA || COMPILE_TEST
+ select SERIAL_CORE
+ help
+ This driver is for RDA8810PL SoC's UART.
+ Say 'Y' here if you wish to use the on-board serial port.
+ Otherwise, say 'N'.
+
+config SERIAL_RDA_CONSOLE
+ bool "Console on RDA Micro serial port"
+ depends on SERIAL_RDA=y
+ select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
+ default y
+ help
+ Say 'Y' here if you wish to use the RDA8810PL 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 fe88a75d9a59..87f5a6e1e2d4 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -93,6 +93,7 @@ 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
+obj-$(CONFIG_SERIAL_RDA) += rda-uart.o
# GPIOLIB helpers for modem control lines
obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c
new file mode 100644
index 000000000000..c3c9cf1df015
--- /dev/null
+++ b/drivers/tty/serial/rda-uart.c
@@ -0,0 +1,117 @@
+/*
+ * RDA8810PL serial console
+ *
+ * Copyright RDA Microelectronics Company Limited
+ * Copyright (c) 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 RDA_UART_CTRL 0x00
+#define RDA_UART_STATUS 0x04
+#define RDA_UART_RXTX_BUFFER 0x08
+#define RDA_UART_IRQ_MASK 0x0c
+
+#define RDA_UART_STATUS_TX_FIFO_SPACE_MASK (0x1f << 8)
+
+static inline void rda_uart_write(struct uart_port *port, u32 val, unsigned int off)
+{
+ writel(val, port->membase + off);
+}
+
+static inline u32 rda_uart_read(struct uart_port *port, unsigned int off)
+{
+ return readl(port->membase + off);
+}
+
+#ifdef CONFIG_SERIAL_RDA_CONSOLE
+
+static void rda_console_putchar(struct uart_port *port, int ch)
+{
+ if (!port->membase)
+ return;
+
+ while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_STATUS_TX_FIFO_SPACE_MASK))
+ cpu_relax();
+
+ rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
+}
+
+static void rda_uart_port_write(struct uart_port *port, const char *s,
+ u_int count)
+{
+ u32 old_irq_mask;
+ 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_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
+ rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
+
+ uart_console_write(port, s, count, rda_console_putchar);
+
+ /* wait until all contents have been sent out */
+ while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_STATUS_TX_FIFO_SPACE_MASK))
+ cpu_relax();
+
+ rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);
+
+ if (locked)
+ spin_unlock(&port->lock);
+
+ local_irq_restore(flags);
+}
+
+static void rda_uart_early_console_write(struct console *co,
+ const char *s,
+ u_int count)
+{
+ struct earlycon_device *dev = co->data;
+
+ rda_uart_port_write(&dev->port, s, count);
+}
+
+static int __init
+rda_uart_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = rda_uart_early_console_write;
+
+ return 0;
+}
+OF_EARLYCON_DECLARE(rda, "rda,8810pl-uart",
+ rda_uart_early_console_setup);
+
+#endif /* CONFIG_SERIAL_RDA_CONSOLE */
--
2.12.3
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