[PATCH v2 5/5] tty/serial: Add earlycon support for Spreadtrum serial driver

Chunyan Zhang
2014-10-17T09:54:25Z

Add serial driver for spreadtrum sharkl platform with earlycon
support at first.

Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
---
drivers/tty/serial/Kconfig | 24 ++++++++++++++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/sprd-serial.c | 64 ++++++++++++++++++++++++++++++++++++++
3 files changed, 89 insertions(+)
create mode 100644 drivers/tty/serial/sprd-serial.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 26cec64..33b8f90 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -113,6 +113,30 @@ config SERIAL_SB1250_DUART_CONSOLE

If unsure, say Y.

+config SERIAL_SPRD
+ tristate "Support for SPRD serial"
+ depends on ARM || ARM64
+ select SERIAL_CORE
+ help
+ This enables the driver for the Spreadtrum's serial.
+
+config SERIAL_SPRD_NR
+ int "Maximum number of sprd serial ports"
+ depends on SERIAL_SPRD
+ default "4"
+
+config SERIAL_SPRD_CONSOLE
+ bool "SPRD UART console support"
+ depends on SERIAL_SPRD=y
+ select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
+ help
+ Support for early debug console using Spreadtrum's serial. This enables
+ the console before standard serial driver is probed. This is enabled
+ with "earlycon=serial_sprd" on the kernel command line. The console is
+ enabled when early_param is processed.
+
+
config SERIAL_ATMEL
bool "AT91 / AT32 on-chip serial port support"
depends on ARCH_AT91 || AVR32
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 0080cc3..b16e0d4 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_SERIAL_ARC) += arc_uart.o
obj-$(CONFIG_SERIAL_RP2) += rp2.o
obj-$(CONFIG_SERIAL_FSL_LPUART) += fsl_lpuart.o
obj-$(CONFIG_SERIAL_MEN_Z135) += men_z135_uart.o
+obj-$(CONFIG_SERIAL_SPRD) += sprd-serial.o

# GPIOLIB helpers for modem control lines
obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/sprd-serial.c b/drivers/tty/serial/sprd-serial.c
new file mode 100644
index 0000000..9ae594f
--- /dev/null
+++ b/drivers/tty/serial/sprd-serial.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012 Spreadtrum Communications Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/serial_core.h>
+#include <linux/of.h>
+
+/*offset*/
+#define UART_TXD 0x0000
+#define UART_RXD 0x0004
+#define UART_STS0 0x0008
+#define UART_STS1 0x000C
+#define UART_IEN 0x0010
+#define UART_ICLR 0x0014
+#define UART_CTL0 0x0018
+#define UART_CTL1 0x001C
+#define UART_CTL2 0x0020
+#define UART_CLKD0 0x0024
+#define UART_CLKD1 0x0028
+#define UART_STS2 0x002C
+
+/*line status */
+#define UART_LSR_TX_OVER (0x1<<15)
+
+static void serial_sprd_putc(struct uart_port *port, int c)
+{
+ while (!(readl(port->membase + UART_STS0) & UART_LSR_TX_OVER))
+ ;
+ writeb(c, port->membase + UART_TXD);
+}
+
+static void serial_sprd_early_write(struct console *con, const char *s,
+ unsigned n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, serial_sprd_putc);
+}
+
+static int __init serial_sprd_early_console_setup(
+ struct earlycon_device *device,
+ const char *opt)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = serial_sprd_early_write;
+ return 0;
+}
+EARLYCON_DECLARE(serial_sprd, serial_sprd_early_console_setup);
+OF_EARLYCON_DECLARE(serial_sprd, "sprd,serial",
+ serial_sprd_early_console_setup);
--
1.7.9.5