Add a full sc9836-uart driver for SC9836 SoC which is based on the
spreadtrum sharkl64 platform.
This driver also support earlycon.

Signed-off-by: Chunyan Zhang<redacted>
Signed-off-by: Orson Zhai<redacted>
Originally-by: Lanqing Liu[off-list ref]
---
  Documentation/devices.txt        |    3 +
  drivers/tty/serial/Kconfig       |   23 ++
  drivers/tty/serial/Makefile      |    1 +
  drivers/tty/serial/sprd_serial.c |  752 ++++++++++++++++++++++++++++++++++++++
  include/uapi/linux/serial_core.h |    3 +
  5 files changed, 782 insertions(+)
  create mode 100644 drivers/tty/serial/sprd_serial.c

diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 87b4c5e..1da0432 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt

@@ -2816,6 +2816,9 @@ Your cooperation is appreciated.
  		 210 = /dev/ttyMAX1		MAX3100 serial port 1
  		 211 = /dev/ttyMAX2		MAX3100 serial port 2
  		 212 = /dev/ttyMAX3		MAX3100 serial port 3
+		 213 = /dev/ttySPX0		SPRD serial port 0
+		    ...
+		 216 = /dev/ttySPX3		SPRD serial port 3

  205 char	Low-density serial ports (alternate device)
  		  0 = /dev/culu0		Callout device for ttyLU0

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 649b784..2c2cf60 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig

@@ -1573,6 +1573,29 @@ config SERIAL_MEN_Z135
  	  This driver can also be build as a module. If so, the module will be called
  	  men_z135_uart.ko

+config SERIAL_SPRD
+	tristate "Support for SPRD serial"
+	depends on ARCH_SPRD
+	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" on the kernel command line. The console is
+	  enabled when early_param is processed.
+
  endmenu

  config SERIAL_MCTRL_GPIO

diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 9a548ac..4801aca 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile

@@ -93,6 +93,7 @@ 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..58214c8
--- /dev/null
+++ b/drivers/tty/serial/sprd_serial.c

@@ -0,0 +1,752 @@
+/*
+ * 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/module.h>
+#include<linux/tty.h>
+#include<linux/ioport.h>
+#include<linux/console.h>
+#include<linux/platform_device.h>
+#include<linux/tty_flip.h>
+#include<linux/serial_core.h>
+#include<linux/serial.h>
+#include<linux/delay.h>
+#include<linux/io.h>
+#include<asm/irq.h>
+#include<linux/slab.h>
+#include<linux/of.h>
+#include<linux/kernel.h>
+#include<linux/slab.h>
+#include<linux/clk.h>

+}
+
+static int sprd_startup(struct uart_port *port)
+{
+	int ret = 0;
+	unsigned int ien, ctrl1;
+	struct sprd_uart_port *sp;
+
+	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY<<  8) | THLD_RX_FULL));
+
+	/* clear rx fifo */
+	while (serial_in(port, SPRD_STS1)&  0x00ff)
+		serial_in(port, SPRD_RXD);
+
+	/* clear tx fifo */
+	while (serial_in(port, SPRD_STS1)&  0xff00)
+		;
+
+	/* clear interrupt */
+	serial_out(port, SPRD_IEN, 0x0);
+	serial_out(port, SPRD_ICLR, ~0);
+
+	/* allocate irq */
+	sp = container_of(port, struct sprd_uart_port, port);
+	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
+	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
+			IRQF_SHARED, sp->name, port);
+	if (ret) {
+		dev_err(port->dev, "fail to request serial irq %d\n",
+			port->irq);
+		return ret;
+	}
+	ctrl1 = serial_in(port, SPRD_CTL1);
+	ctrl1 |= 0x3e00 | THLD_RX_FULL;
+	serial_out(port, SPRD_CTL1, ctrl1);
+
+	/* enable interrupt */
+	spin_lock(&port->lock);
+	ien = serial_in(port, SPRD_IEN);
+	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	serial_out(port, SPRD_IEN, ien);
+	spin_unlock(&port->lock);
+
+	return 0;
+}
+
+static void sprd_shutdown(struct uart_port *port)
+{
+	serial_out(port, SPRD_IEN, 0x0);
+	serial_out(port, SPRD_ICLR, ~0);
+	devm_free_irq(port->dev, port->irq, port);
+}
+
+static void sprd_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    struct ktermios *old)
+{
+	unsigned int baud, quot;
+	unsigned int lcr, fc;
+
+	/* ask the core to calculate the divisor for us */
+	baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);
+
+	quot = (unsigned int)((port->uartclk + baud / 2) / baud);
+
+	/* set data length */
+	lcr = serial_in(port, SPRD_LCR);
+	lcr&= ~SPRD_LCR_DATA_LEN;
+	switch (termios->c_cflag&  CSIZE) {
+	case CS5:
+		lcr |= SPRD_LCR_DATA_LEN5;
+		break;
+	case CS6:
+		lcr |= SPRD_LCR_DATA_LEN6;
+		break;
+	case CS7:
+		lcr |= SPRD_LCR_DATA_LEN7;
+		break;
+	case CS8:
+	default:
+		lcr |= SPRD_LCR_DATA_LEN8;
+		break;
+	}
+
+	/* calculate stop bits */
+	lcr&= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
+	if (termios->c_cflag&  CSTOPB)
+		lcr |= SPRD_LCR_STOP_2BIT;
+	else
+		lcr |= SPRD_LCR_STOP_1BIT;
+
+	/* calculate parity */
+	lcr&= ~SPRD_LCR_PARITY;
+	if (termios->c_cflag&  PARENB) {
+		lcr |= SPRD_LCR_PARITY_EN;
+		if (termios->c_cflag&  PARODD)
+			lcr |= SPRD_LCR_ODD_PAR;
+		else
+			lcr |= SPRD_LCR_EVEN_PAR;
+	}
+
+	/* change the port state. */
+	/* update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	port->read_status_mask = SPRD_LSR_OE;
+	if (termios->c_iflag&  INPCK)
+		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
+	if (termios->c_iflag&  (BRKINT | PARMRK))
+		port->read_status_mask |= SPRD_LSR_BI;
+
+	/* characters to ignore */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag&  IGNPAR)
+		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
+	if (termios->c_iflag&  IGNBRK) {
+		port->ignore_status_mask |= SPRD_LSR_BI;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag&  IGNPAR)
+			port->ignore_status_mask |= SPRD_LSR_OE;
+	}
+
+	/* flow control */
+	fc = serial_in(port, SPRD_CTL1);
+	fc&= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
+	if (termios->c_cflag&  CRTSCTS) {
+		fc |= RX_HW_FLOW_CTL_THLD;
+		fc |= RX_HW_FLOW_CTL_EN;
+		fc |= TX_HW_FLOW_CTL_EN;
+	}
+
+	/* clock divider bit0~bit15 */
+	serial_out(port, SPRD_CLKD0, quot&  0xffff);
+
+	/* clock divider bit16~bit20 */
+	serial_out(port, SPRD_CLKD1, (quot&  0x1f0000)>>  16);
+	serial_out(port, SPRD_LCR, lcr);
+	fc |= 0x3e00 | THLD_RX_FULL;
+	serial_out(port, SPRD_CTL1, fc);
+}
+
+static const char *sprd_type(struct uart_port *port)
+{
+	return "SPX";
+}
+
+static void sprd_release_port(struct uart_port *port)
+{
+	/* nothing to do */
+}
+
+static int sprd_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void sprd_config_port(struct uart_port *port, int flags)
+{
+	if (flags&  UART_CONFIG_TYPE)
+		port->type = PORT_SPRD;
+}
+
+static int sprd_verify_port(struct uart_port *port,
+				   struct serial_struct *ser)
+{
+	if (unlikely(ser->type != PORT_SPRD))
+		return -EINVAL;
+	if (unlikely(port->irq != ser->irq))
+		return -EINVAL;
+	return 0;
+}
+
+static struct uart_ops serial_sprd_ops = {
+	.tx_empty = sprd_tx_empty,
+	.get_mctrl = sprd_get_mctrl,
+	.set_mctrl = sprd_set_mctrl,
+	.stop_tx = sprd_stop_tx,
+	.start_tx = sprd_start_tx,
+	.stop_rx = sprd_stop_rx,
+	.break_ctl = sprd_break_ctl,
+	.startup = sprd_startup,
+	.shutdown = sprd_shutdown,
+	.set_termios = sprd_set_termios,
+	.type = sprd_type,
+	.release_port = sprd_release_port,
+	.request_port = sprd_request_port,
+	.config_port = sprd_config_port,
+	.verify_port = sprd_verify_port,
+};
+
+#ifdef CONFIG_SERIAL_SPRD_CONSOLE
+static inline void wait_for_xmitr(struct uart_port *port)
+{
+	unsigned int status, tmout = 10000;
+
+	/* wait up to 10ms for the character(s) to be sent */
+	do {
+		status = serial_in(port, SPRD_STS1);
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (status&  0xff00);
+}
+
+static void sprd_console_putchar(struct uart_port *port, int ch)
+{
+	wait_for_xmitr(port);
+	serial_out(port, SPRD_TXD, ch);
+}
+
+static void sprd_console_write(struct console *co, const char *s,
+				      unsigned int count)
+{
+	struct uart_port *port = (struct uart_port *)sprd_port[co->index];
+	int ien;
+	int locked = 1;
+
+	if (oops_in_progress)
+		locked = spin_trylock(&port->lock);
+	else
+		spin_lock(&port->lock);
+	/* save the IEN then disable the interrupts */
+	ien = serial_in(port, SPRD_IEN);
+	serial_out(port, SPRD_IEN, 0x0);
+
+	uart_console_write(port, s, count, sprd_console_putchar);
+
+	/* wait for transmitter to become empty and restore the IEN */
+	wait_for_xmitr(port);
+	serial_out(port, SPRD_IEN, ien);
+	if (locked)
+		spin_unlock(&port->lock);
+}
+
+static int __init sprd_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (unlikely(co->index>= UART_NR_MAX || co->index<  0))
+		co->index = 0;
+
+	port = (struct uart_port *)sprd_port[co->index];
+	if (port == NULL) {
+		pr_info("srial port %d not yet initialized\n", co->index);
+		return -ENODEV;
+	}
+	if (options)
+		uart_parse_options(options,&baud,&parity,&bits,&flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver sprd_uart_driver;
+static struct console sprd_console = {
+	.name = SPRD_TTY_NAME,
+	.write = sprd_console_write,
+	.device = uart_console_device,
+	.setup = sprd_console_setup,
+	.flags = CON_PRINTBUFFER,
+	.index = -1,
+	.data =&sprd_uart_driver,
+};
+
+#define SPRD_CONSOLE	(&sprd_console)
+
+/* Support for earlycon */
+static void sprd_putc(struct uart_port *port, int c)
+{
+	while (!(readl(port->membase + SPRD_LSR)&  SPRD_LSR_TX_OVER))
+		;
+	writeb(c, port->membase + SPRD_TXD);
+}
+
+static void sprd_early_write(struct console *con, const char *s,
+				    unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, sprd_putc);
+}
+
+static int __init sprd_early_console_setup(
+				struct earlycon_device *device,
+				const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = sprd_early_write;
+	return 0;
+}
+
+EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
+OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
+		    sprd_early_console_setup);
+
+#else /* !CONFIG_SERIAL_SPRD_CONSOLE */
+#define SPRD_CONSOLE		NULL
+#endif
+
+static struct uart_driver sprd_uart_driver = {
+	.owner = THIS_MODULE,
+	.driver_name = "sprd_serial",
+	.dev_name = SPRD_TTY_NAME,
+	.major = SPRD_TTY_MAJOR,
+	.minor = SPRD_TTY_MINOR_START,
+	.nr = UART_NR_MAX,
+	.cons = SPRD_CONSOLE,
+};
+
+static int sprd_probe(struct platform_device *pdev)
+{
+	struct resource *mem;
+	struct device_node *np = pdev->dev.of_node;
+	struct uart_port *up;
+	struct clk *clk;
+	int irq;
+
+
+	if (np)
+		pdev->id = of_alias_get_id(np, "serial");
+
+	if (unlikely(pdev->id<  0 || pdev->id>= UART_NR_MAX)) {
+		dev_err(&pdev->dev, "does not support id %d\n", pdev->id);
+		return -ENXIO;
+	}
+
+	sprd_port[pdev->id] = devm_kzalloc(&pdev->dev,
+		sizeof(*sprd_port[pdev->id]), GFP_KERNEL);
+	if (!sprd_port[pdev->id])
+		return -ENOMEM;
+
+	up = (struct uart_port *)sprd_port[pdev->id];
+	up->dev =&pdev->dev;
+	up->line = pdev->id;
+	up->type = PORT_SPRD;
+	up->iotype = SERIAL_IO_PORT;
+	up->uartclk = SPRD_DEF_RATE;
+	up->fifosize = SPRD_FIFO_SIZE;
+	up->ops =&serial_sprd_ops;
+	up->flags = ASYNC_BOOT_AUTOCONF;
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (!IS_ERR(clk))
+		up->uartclk = clk_get_rate(clk);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (unlikely(!mem)) {
+		dev_err(&pdev->dev, "not provide mem resource\n");
+		return -ENODEV;
+	}
+	up->mapbase = mem->start;
+	up->membase = ioremap(mem->start, resource_size(mem));
+
+	irq = platform_get_irq(pdev, 0);
+	if (unlikely(irq<  0)) {
+		dev_err(&pdev->dev, "not provide irq resource\n");
+		return -ENODEV;
+	}
+	up->irq = irq;
+
+	platform_set_drvdata(pdev, up);
+
+	return uart_add_one_port(&sprd_uart_driver, up);
+}
+
+static int sprd_remove(struct platform_device *dev)
+{
+	struct uart_port *up = platform_get_drvdata(dev);
+
+	return uart_remove_one_port(&sprd_uart_driver, up);
+}
+
+static int sprd_suspend(struct platform_device *dev, pm_message_t state)
+{
+	int id = dev->id;
+	struct uart_port *port = (struct uart_port *)sprd_port[id];
+	struct reg_backup *reg_bak =&(sprd_port[id]->reg_bak);
+
+	reg_bak->ien = serial_in(port, SPRD_IEN);
+	reg_bak->ctrl0 = serial_in(port, SPRD_LCR);
+	reg_bak->ctrl1 = serial_in(port, SPRD_CTL1);
+	reg_bak->ctrl2 = serial_in(port, SPRD_CTL2);
+	reg_bak->clkd0 = serial_in(port, SPRD_CLKD0);
+	reg_bak->clkd1 = serial_in(port, SPRD_CLKD1);
+
+	return 0;
+}
+
+static int sprd_resume(struct platform_device *dev)
+{
+	int id = dev->id;
+	struct uart_port *port = (struct uart_port *)sprd_port[id];
+	struct reg_backup *reg_bak =&(sprd_port[id]->reg_bak);
+
+	serial_out(port, SPRD_LCR, reg_bak->ctrl0);
+	serial_out(port, SPRD_CTL1, reg_bak->ctrl1);
+	serial_out(port, SPRD_CTL2, reg_bak->ctrl2);
+	serial_out(port, SPRD_CLKD0, reg_bak->clkd0);
+	serial_out(port, SPRD_CLKD1, reg_bak->clkd1);
+	serial_out(port, SPRD_IEN, reg_bak->ien);
+
+	return 0;
+}
+
+static const struct of_device_id serial_ids[] = {
+	{.compatible = "sprd,sc9836-uart",},
+	{}
+};
+
+static struct platform_driver sprd_platform_driver = {
+	.probe = sprd_probe,
+	.remove = sprd_remove,
+	.suspend = sprd_suspend,
+	.resume = sprd_resume,
+	.driver = {
+		   .name = "sprd_serial",
+		   .owner = THIS_MODULE,
+		   .of_match_table = of_match_ptr(serial_ids),
+		   },
+};
+
+static int __init sprd_serial_init(void)
+{
+	int ret = 0;
+
+	ret = uart_register_driver(&sprd_uart_driver);
+	if (unlikely(ret != 0))
+		return ret;
+
+	ret = platform_driver_register(&sprd_platform_driver);
+	if (unlikely(ret != 0))
+		uart_unregister_driver(&sprd_uart_driver);
+
+	return ret;
+}
+
+static void __exit sprd_serial_exit(void)
+{
+	platform_driver_unregister(&sprd_platform_driver);
+	uart_unregister_driver(&sprd_uart_driver);
+}
+
+module_init(sprd_serial_init);
+module_exit(sprd_serial_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");

diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 16ad852..d9a8c88 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h

@@ -247,4 +247,7 @@
  /* MESON */
  #define PORT_MESON	109

+/* SPRD SERIAL  */
+#define PORT_SPRD   110
+
  #endif /* _UAPILINUX_SERIAL_CORE_H */