Add Spreadtrum SoC bindings and serial driver support

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

This patch also replaced the spaces between the macros and their values with the tabs in serial_core.h

Originally-by Lanqing Liu <[email protected]>

Signed-off-by Orson Zhai <[email protected]>

Signed-off-by Chunyan Zhang <[email protected]>

---

 drivers/tty/serial/Kconfig       |   18 +
 drivers/tty/serial/Makefile      |    1 +
 drivers/tty/serial/sprd_serial.c |  801 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/serial_core.h |    3 +
 4 files changed, 823 insertions(+)
 create mode 100644 drivers/tty/serial/sprd_serial.c

drivers/tty/serial/Kconfig +18 -0

index c79b43c..13211f7 100644
@@ -1577,6 +1577,24 @@ 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 Spreadtrum serial"
+	depends on ARCH_SPRD
+	select SERIAL_CORE
+	help
+	  This enables the driver for the Spreadtrum's serial.
+
+config SERIAL_SPRD_CONSOLE
+	bool "Spreadtrum 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

drivers/tty/serial/Makefile +1 -0

index 9a548ac..4801aca 100644
@@ -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

drivers/tty/serial/sprd_serial.c new file +89 -0

new file mode 100644
index 0000000..fd98541
@@ -0,0 +1,801 @@
+/*
+ * Copyright (C) 2012-2015 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/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/* device name */
+#define UART_NR_MAX		8
+#define SPRD_TTY_NAME		"ttyS"
+#define SPRD_FIFO_SIZE		128
+#define SPRD_DEF_RATE		26000000
+#define SPRD_TIMEOUT		2048
+
+/* the offset of serial registers and BITs for them */
+/* data registers */
+#define SPRD_TXD		0x0000
+#define SPRD_RXD		0x0004
+
+/* line status register and its BITs  */
+#define SPRD_LSR		0x0008
+#define SPRD_LSR_OE		BIT(4)
+#define SPRD_LSR_FE		BIT(3)
+#define SPRD_LSR_PE		BIT(2)
+#define SPRD_LSR_BI		BIT(7)
+#define SPRD_LSR_TX_OVER	BIT(15)
+
+/* data number in TX and RX fifo */
+#define SPRD_STS1		0x000C
+
+/* interrupt enable register and its BITs */
+#define SPRD_IEN		0x0010
+#define SPRD_IEN_RX_FULL	BIT(0)
+#define SPRD_IEN_TX_EMPTY	BIT(1)
+#define SPRD_IEN_BREAK_DETECT	BIT(7)
+#define SPRD_IEN_TIMEOUT	BIT(13)
+
+/* interrupt clear register */
+#define SPRD_ICLR		0x0014
+
+/* line control register */
+#define SPRD_LCR		0x0018
+#define SPRD_LCR_STOP_1BIT	0x10
+#define SPRD_LCR_STOP_2BIT	0x30
+#define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
+#define SPRD_LCR_DATA_LEN5	0x0
+#define SPRD_LCR_DATA_LEN6	0x4
+#define SPRD_LCR_DATA_LEN7	0x8
+#define SPRD_LCR_DATA_LEN8	0xc
+#define SPRD_LCR_PARITY		(BIT(0) | BIT(1))
+#define SPRD_LCR_PARITY_EN	0x2
+#define SPRD_LCR_EVEN_PAR	0x0
+#define SPRD_LCR_ODD_PAR	0x1
+
+/* control register 1 */
+#define SPRD_CTL1		0x001C
+#define RX_HW_FLOW_CTL_THLD	BIT(6)
+#define RX_HW_FLOW_CTL_EN	BIT(7)
+#define TX_HW_FLOW_CTL_EN	BIT(8)
+
+/* fifo threshold register */
+#define SPRD_CTL2		0x0020
+#define THLD_TX_EMPTY		0x40
+#define THLD_RX_FULL		0x40
+
+/* config baud rate register */
+#define SPRD_CLKD0		0x0024
+#define SPRD_CLKD1		0x0028

drivers/tty/serial/sprd_serial.c new file +5 -0

+	uint32_t ctrl0;
+	uint32_t ctrl1;
+	uint32_t ctrl2;
+	uint32_t clkd0;
+	uint32_t clkd1;

drivers/tty/serial/sprd_serial.c new file +67 -0

+
+static inline unsigned int serial_in(struct uart_port *port, int offset)
+{
+	return readl_relaxed(port->membase + offset);
+}
+
+static inline void serial_out(struct uart_port *port, int offset, int value)
+{
+	writel_relaxed(value, port->membase + offset);
+}
+
+static unsigned int sprd_tx_empty(struct uart_port *port)
+{
+	if (serial_in(port, SPRD_STS1) & 0xff00)
+		return 0;
+	else
+		return TIOCSER_TEMT;
+}
+
+static unsigned int sprd_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_DSR | TIOCM_CTS;
+}
+
+static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/* nothing to do */
+}
+
+static void sprd_stop_tx(struct uart_port *port)
+{
+	unsigned int ien, iclr;
+
+	iclr = serial_in(port, SPRD_ICLR);
+	ien = serial_in(port, SPRD_IEN);
+
+	iclr |= SPRD_IEN_TX_EMPTY;
+	ien &= ~SPRD_IEN_TX_EMPTY;
+
+	serial_out(port, SPRD_ICLR, iclr);
+	serial_out(port, SPRD_IEN, ien);
+}
+
+static void sprd_start_tx(struct uart_port *port)
+{
+	unsigned int ien;
+
+	ien = serial_in(port, SPRD_IEN);
+	if (!(ien & SPRD_IEN_TX_EMPTY)) {
+		ien |= SPRD_IEN_TX_EMPTY;
+		serial_out(port, SPRD_IEN, ien);
+	}
+}
+
+static void sprd_stop_rx(struct uart_port *port)
+{
+	unsigned int ien, iclr;
+
+	iclr = serial_in(port, SPRD_ICLR);
+	ien = serial_in(port, SPRD_IEN);
+
+	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
+	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
+
+	serial_out(port, SPRD_IEN, ien);
+	serial_out(port, SPRD_ICLR, iclr);
+}

drivers/tty/serial/sprd_serial.c new file +20 -0

+{
+	int ret = 0;
+
+	/* statistics */
+	if (*lsr & SPRD_LSR_BI) {
+		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
+		port->icount.brk++;
+		ret = uart_handle_break(port);
+		if (ret)
+			return ret;
+	} else if (*lsr & SPRD_LSR_PE)
+		port->icount.parity++;
+	else if (*lsr & SPRD_LSR_FE)
+		port->icount.frame++;
+	if (*lsr & SPRD_LSR_OE)
+		port->icount.overrun++;
+
+	/* mask off conditions which should be ignored */
+	*lsr &= port->read_status_mask;
+	if (*lsr & SPRD_LSR_BI)

drivers/tty/serial/sprd_serial.c new file +25 -0

+	struct circ_buf *xmit = &port->state->xmit;
+	int count;
+
+	if (port->x_char) {
+		serial_out(port, SPRD_TXD, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		sprd_stop_tx(port);
+		return;
+	}
+
+	count = THLD_TX_EMPTY;
+	do {
+		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	} while (--count > 0);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)

drivers/tty/serial/sprd_serial.c new file +19 -0

+	unsigned int ims;
+
+	spin_lock(&port->lock);
+
+	ims = serial_in(port, SPRD_IMSR);
+
+	if (!ims)
+		return IRQ_NONE;
+
+	serial_out(port, SPRD_ICLR, ~0);
+
+	if (ims & (SPRD_IMSR_RX_FIFO_FULL |
+		SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
+		sprd_rx(irq, port);
+
+	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
+		sprd_tx(irq, port);
+
+	spin_unlock(&port->lock);

drivers/tty/serial/sprd_serial.c new file +5 -0

+
+	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
+
+	/* clear rx fifo */
+	timeout = SPRD_TIMEOUT;

drivers/tty/serial/sprd_serial.c new file +4 -0

+	serial_out(port, SPRD_ICLR, ~0);
+
+	/* allocate irq */
+	sp = container_of(port, struct sprd_uart_port, port);

drivers/tty/serial/sprd_serial.c new file +4 -0

+	serial_out(port, SPRD_ICLR, ~0);
+	devm_free_irq(port->dev, port->irq, port);
+}
+

drivers/tty/serial/sprd_serial.c new file +33 -0

+	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;
+	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
+	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;
+	}

drivers/tty/serial/sprd_serial.c new file +109 -0

+		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);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	/* Don't rewrite B0 */
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+}
+
+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 (ser->type != PORT_SPRD)
+		return -EINVAL;
+	if (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);
+}

drivers/tty/serial/sprd_serial.c new file +114 -0

+	else
+		spin_lock_irqsave(&port->lock, flags);
+
+	uart_console_write(port, s, count, sprd_console_putchar);
+
+	/* wait for transmitter to become empty */
+	wait_for_xmitr(port);
+
+	if (locked)
+		spin_unlock_irqrestore(&port->lock, flags);
+}
+
+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 (co->index >= UART_NR_MAX || co->index < 0)
+		co->index = 0;
+
+	port = &sprd_port[co->index]->port;
+	if (port == NULL) {
+		pr_info("serial 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)
+{
+	unsigned int timeout = SPRD_TIMEOUT;
+
+	while (timeout-- &&
+		   !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
+		cpu_relax();
+
+	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 = 0,
+	.minor = 0,
+	.nr = UART_NR_MAX,
+	.cons = SPRD_CONSOLE,
+};
+
+static int sprd_probe_dt_alias(int index, struct device *dev)
+{
+	struct device_node *np;
+	static bool seen_dev_with_alias;
+	static bool seen_dev_without_alias;
+	int ret = index;
+
+	if (!IS_ENABLED(CONFIG_OF))
+		return ret;
+
+	np = dev->of_node;
+	if (!np)
+		return ret;
+
+	ret = of_alias_get_id(np, "serial");
+	if (IS_ERR_VALUE(ret)) {
+		seen_dev_without_alias = true;
+		ret = index;

drivers/tty/serial/sprd_serial.c new file +35 -0

+
+	for (i = 0; i < ARRAY_SIZE(sprd_port); i++)
+		if (sprd_port[i] == sup)
+			sprd_port[i] = NULL;
+		else if (sprd_port[i])
+			busy = true;
+
+	if (!busy)
+		uart_unregister_driver(&sprd_uart_driver);
+
+	return 0;
+}
+
+static int sprd_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct uart_port *up;
+	struct clk *clk;
+	int irq;
+	int index;
+	int ret;
+
+	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
+		if (sprd_port[index] == NULL)
+			break;
+
+	if (index == ARRAY_SIZE(sprd_port))
+		return -EBUSY;
+
+	index = sprd_probe_dt_alias(index, &pdev->dev);
+
+	sprd_port[index] = devm_kzalloc(&pdev->dev,
+		sizeof(*sprd_port[index]), GFP_KERNEL);
+	if (!sprd_port[index])
+		return -ENOMEM;

drivers/tty/serial/sprd_serial.c new file +13 -0

+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (!IS_ERR(clk))
+		up->uartclk = clk_get_rate(clk);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "not provide mem resource\n");
+		return -ENODEV;
+	}
+	up->mapbase = res->start;
+	up->membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(up->membase))

drivers/tty/serial/sprd_serial.c new file +5 -0

+	ret = uart_add_one_port(&sprd_uart_driver, up);
+	if (ret) {
+		sprd_port[index] = NULL;
+		sprd_remove(pdev);
+	}

drivers/tty/serial/sprd_serial.c new file +37 -0

+
+	uart_suspend_port(&sprd_uart_driver, port);
+
+	return 0;
+}
+
+static int sprd_resume(struct device *dev)
+{
+	int id = to_platform_device(dev)->id;
+	struct uart_port *port = &sprd_port[id]->port;
+
+	uart_resume_port(&sprd_uart_driver, port);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
+
+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,
+	.driver		= {
+		.name	= "sprd_serial",
+		.of_match_table = of_match_ptr(serial_ids),
+		.pm	= &sprd_pm_ops,
+	},
+};
+
+module_platform_driver(sprd_platform_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");

include/uapi/linux/serial_core.h +3 -0

index c172180..7e6eb39 100644
@@ -248,4 +248,7 @@
 /* MESON */
 #define PORT_MESON	109
 
+/* SPRD SERIAL  */
+#define PORT_SPRD	110
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */

Hi Chunyan,

Quoted 3 lines · Chunyan Zhang

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

Looking good. Comments below.

Quoted 2 lines

This patch also replaced the spaces between the macros and their values with the tabs in serial_core.h

Notes about patch changes goes...

Quoted 1 line

Quoted 4 lines

Originally-by Lanqing Liu <[email protected]>

Signed-off-by Orson Zhai <[email protected]>

Signed-off-by Chunyan Zhang <[email protected]>

---

...here. For example,

* Replaced spaces with tab for PORT_SPRD define in serial_core.h

Quoted 143 lines

 drivers/tty/serial/Kconfig       |   18 +
 drivers/tty/serial/Makefile      |    1 +
 drivers/tty/serial/sprd_serial.c |  801 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/serial_core.h |    3 +
 4 files changed, 823 insertions(+)
 create mode 100644 drivers/tty/serial/sprd_serial.c

drivers/tty/serial/Kconfig +18 -0

index c79b43c..13211f7 100644
@@ -1577,6 +1577,24 @@ 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 Spreadtrum serial"
+     depends on ARCH_SPRD
+     select SERIAL_CORE
+     help
+       This enables the driver for the Spreadtrum's serial.
+
+config SERIAL_SPRD_CONSOLE
+     bool "Spreadtrum 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

drivers/tty/serial/Makefile +1 -0

index 9a548ac..4801aca 100644
@@ -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

drivers/tty/serial/sprd_serial.c new file +89 -0

new file mode 100644
index 0000000..fd98541
@@ -0,0 +1,801 @@
+/*
+ * Copyright (C) 2012-2015 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/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/* device name */
+#define UART_NR_MAX          8
+#define SPRD_TTY_NAME                "ttyS"
+#define SPRD_FIFO_SIZE               128
+#define SPRD_DEF_RATE                26000000
+#define SPRD_TIMEOUT         2048
+
+/* the offset of serial registers and BITs for them */
+/* data registers */
+#define SPRD_TXD             0x0000
+#define SPRD_RXD             0x0004
+
+/* line status register and its BITs  */
+#define SPRD_LSR             0x0008
+#define SPRD_LSR_OE          BIT(4)
+#define SPRD_LSR_FE          BIT(3)
+#define SPRD_LSR_PE          BIT(2)
+#define SPRD_LSR_BI          BIT(7)
+#define SPRD_LSR_TX_OVER     BIT(15)
+
+/* data number in TX and RX fifo */
+#define SPRD_STS1            0x000C
+
+/* interrupt enable register and its BITs */
+#define SPRD_IEN             0x0010
+#define SPRD_IEN_RX_FULL     BIT(0)
+#define SPRD_IEN_TX_EMPTY    BIT(1)
+#define SPRD_IEN_BREAK_DETECT        BIT(7)
+#define SPRD_IEN_TIMEOUT     BIT(13)
+
+/* interrupt clear register */
+#define SPRD_ICLR            0x0014
+
+/* line control register */
+#define SPRD_LCR             0x0018
+#define SPRD_LCR_STOP_1BIT   0x10
+#define SPRD_LCR_STOP_2BIT   0x30
+#define SPRD_LCR_DATA_LEN    (BIT(2) | BIT(3))
+#define SPRD_LCR_DATA_LEN5   0x0
+#define SPRD_LCR_DATA_LEN6   0x4
+#define SPRD_LCR_DATA_LEN7   0x8
+#define SPRD_LCR_DATA_LEN8   0xc
+#define SPRD_LCR_PARITY              (BIT(0) | BIT(1))
+#define SPRD_LCR_PARITY_EN   0x2
+#define SPRD_LCR_EVEN_PAR    0x0
+#define SPRD_LCR_ODD_PAR     0x1
+
+/* control register 1 */
+#define SPRD_CTL1            0x001C
+#define RX_HW_FLOW_CTL_THLD  BIT(6)
+#define RX_HW_FLOW_CTL_EN    BIT(7)
+#define TX_HW_FLOW_CTL_EN    BIT(8)
+
+/* fifo threshold register */
+#define SPRD_CTL2            0x0020
+#define THLD_TX_EMPTY                0x40
+#define THLD_RX_FULL         0x40
+
+/* config baud rate register */
+#define SPRD_CLKD0           0x0024
+#define SPRD_CLKD1           0x0028

drivers/tty/serial/sprd_serial.c line 99

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+/* interrupt mask status register */
+#define SPRD_IMSR            0x002C
+#define SPRD_IMSR_RX_FIFO_FULL       BIT(0)
+#define SPRD_IMSR_TX_FIFO_EMPTY      BIT(1)
+#define SPRD_IMSR_BREAK_DETECT       BIT(7)
+#define SPRD_IMSR_TIMEOUT    BIT(13)
+
+struct reg_backup {
+     uint32_t ien;

        u32     ien;

same for others

Quoted 5 lines

drivers/tty/serial/sprd_serial.c new file +5 -0

+     uint32_t ctrl0;
+     uint32_t ctrl1;
+     uint32_t ctrl2;
+     uint32_t clkd0;
+     uint32_t clkd1;

drivers/tty/serial/sprd_serial.c line 114

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+     uint32_t dspwait;
+};
+
+struct sprd_uart_port {
+     struct uart_port port;
+     struct reg_backup reg_bak;
+     char name[16];
+};
+
+static struct sprd_uart_port *sprd_port[UART_NR_MAX] = { NULL };

                                                        ^^^^^^^^^^

Don't need the initializer.

Quoted 67 lines

drivers/tty/serial/sprd_serial.c new file +67 -0

+
+static inline unsigned int serial_in(struct uart_port *port, int offset)
+{
+     return readl_relaxed(port->membase + offset);
+}
+
+static inline void serial_out(struct uart_port *port, int offset, int value)
+{
+     writel_relaxed(value, port->membase + offset);
+}
+
+static unsigned int sprd_tx_empty(struct uart_port *port)
+{
+     if (serial_in(port, SPRD_STS1) & 0xff00)
+             return 0;
+     else
+             return TIOCSER_TEMT;
+}
+
+static unsigned int sprd_get_mctrl(struct uart_port *port)
+{
+     return TIOCM_DSR | TIOCM_CTS;
+}
+
+static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+     /* nothing to do */
+}
+
+static void sprd_stop_tx(struct uart_port *port)
+{
+     unsigned int ien, iclr;
+
+     iclr = serial_in(port, SPRD_ICLR);
+     ien = serial_in(port, SPRD_IEN);
+
+     iclr |= SPRD_IEN_TX_EMPTY;
+     ien &= ~SPRD_IEN_TX_EMPTY;
+
+     serial_out(port, SPRD_ICLR, iclr);
+     serial_out(port, SPRD_IEN, ien);
+}
+
+static void sprd_start_tx(struct uart_port *port)
+{
+     unsigned int ien;
+
+     ien = serial_in(port, SPRD_IEN);
+     if (!(ien & SPRD_IEN_TX_EMPTY)) {
+             ien |= SPRD_IEN_TX_EMPTY;
+             serial_out(port, SPRD_IEN, ien);
+     }
+}
+
+static void sprd_stop_rx(struct uart_port *port)
+{
+     unsigned int ien, iclr;
+
+     iclr = serial_in(port, SPRD_ICLR);
+     ien = serial_in(port, SPRD_IEN);
+
+     ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
+     iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
+
+     serial_out(port, SPRD_IEN, ien);
+     serial_out(port, SPRD_ICLR, iclr);
+}

drivers/tty/serial/sprd_serial.c line 191

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+/* The Sprd serial does not support this function. */
+static void sprd_break_ctl(struct uart_port *port, int break_state)
+{
+     /* nothing to do */
+}
+
+static inline int handle_lsr_errors(struct uart_port *port,
+                                 unsigned int *flag,
+                                 unsigned int *lsr)

Don't declare this inline. gcc will inline single call site functions.

Quoted 20 lines

drivers/tty/serial/sprd_serial.c new file +20 -0

+{
+     int ret = 0;
+
+     /* statistics */
+     if (*lsr & SPRD_LSR_BI) {
+             *lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
+             port->icount.brk++;
+             ret = uart_handle_break(port);
+             if (ret)
+                     return ret;
+     } else if (*lsr & SPRD_LSR_PE)
+             port->icount.parity++;
+     else if (*lsr & SPRD_LSR_FE)
+             port->icount.frame++;
+     if (*lsr & SPRD_LSR_OE)
+             port->icount.overrun++;
+
+     /* mask off conditions which should be ignored */
+     *lsr &= port->read_status_mask;
+     if (*lsr & SPRD_LSR_BI)

drivers/tty/serial/sprd_serial.c line 221

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+             *flag = TTY_BREAK;
+     else if (*lsr & SPRD_LSR_PE)
+             *flag = TTY_PARITY;
+     else if (*lsr & SPRD_LSR_FE)
+             *flag = TTY_FRAME;
+
+     return ret;
+}
+
+static inline void sprd_rx(int irq, void *dev_id)

^^^^^^^^^^^^ struct uart_port *port

The 'irq' parameter is unused, remove it.
Don't declare inline.

drivers/tty/serial/sprd_serial.c line 223

Quoted 2 lines

drivers/tty/serial/sprd_serial.c new file +2 -0

+{
+     struct uart_port *port = dev_id;

        ^^^^^^^^^

delete this line.

drivers/tty/serial/sprd_serial.c line 225

Quoted 2 lines

drivers/tty/serial/sprd_serial.c new file +2 -0

+     struct tty_port *tty = &port->state->port;
+     unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;

                                                ^^^^^^^^^
                                                == 2048?

That's a lot. Most (all?) other drivers use 256.

drivers/tty/serial/sprd_serial.c line 234

Quoted 9 lines

drivers/tty/serial/sprd_serial.c new file +9 -0

+
+     while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
+             lsr = serial_in(port, SPRD_LSR);
+             ch = serial_in(port, SPRD_RXD);
+             flag = TTY_NORMAL;
+             port->icount.rx++;
+
+             if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE
+                     | SPRD_LSR_FE | SPRD_LSR_OE))

operators should trail on the previous line, like

if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
SPRD_LSR_FE | SPRD_LSR_OE))

drivers/tty/serial/sprd_serial.c line 246

Quoted 12 lines

drivers/tty/serial/sprd_serial.c new file +12 -0

+                     if (handle_lsr_errors(port, &lsr, &flag))
+                             continue;
+             if (uart_handle_sysrq_char(port, ch))
+                     continue;
+
+             uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
+     }
+
+     tty_flip_buffer_push(tty);
+}
+
+static inline void sprd_tx(int irq, void *dev_id)

^^^^^^^^^^^^^ struct uart_port *port

The 'irq' parameter is unused, remove it.
Don't declare inline.

drivers/tty/serial/sprd_serial.c line 248

Quoted 2 lines

drivers/tty/serial/sprd_serial.c new file +2 -0

+{
+     struct uart_port *port = dev_id;

         ^^^^^^^^^

delete this line.

Quoted 25 lines

drivers/tty/serial/sprd_serial.c new file +25 -0

+     struct circ_buf *xmit = &port->state->xmit;
+     int count;
+
+     if (port->x_char) {
+             serial_out(port, SPRD_TXD, port->x_char);
+             port->icount.tx++;
+             port->x_char = 0;
+             return;
+     }
+
+     if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+             sprd_stop_tx(port);
+             return;
+     }
+
+     count = THLD_TX_EMPTY;
+     do {
+             serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
+             xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+             port->icount.tx++;
+             if (uart_circ_empty(xmit))
+                     break;
+     } while (--count > 0);
+
+     if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)

drivers/tty/serial/sprd_serial.c line 283

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+             uart_write_wakeup(port);
+
+     if (uart_circ_empty(xmit))
+             sprd_stop_tx(port);
+}
+
+/* this handles the interrupt from one port */
+static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
+{
+     struct uart_port *port = (struct uart_port *)dev_id;

                                    ^^^^^^^^^^^

Don't need the type cast.

Quoted 19 lines

drivers/tty/serial/sprd_serial.c new file +19 -0

+     unsigned int ims;
+
+     spin_lock(&port->lock);
+
+     ims = serial_in(port, SPRD_IMSR);
+
+     if (!ims)
+             return IRQ_NONE;
+
+     serial_out(port, SPRD_ICLR, ~0);
+
+     if (ims & (SPRD_IMSR_RX_FIFO_FULL |
+             SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
+             sprd_rx(irq, port);
+
+     if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
+             sprd_tx(irq, port);
+
+     spin_unlock(&port->lock);

drivers/tty/serial/sprd_serial.c line 312

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     return IRQ_HANDLED;
+}
+
+static int sprd_startup(struct uart_port *port)
+{
+     int ret = 0;
+     unsigned int ien, ctrl1;
+     unsigned int timeout;
+     struct sprd_uart_port *sp;

        unsigned long flags;

Quoted 5 lines

drivers/tty/serial/sprd_serial.c new file +5 -0

+
+     serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
+
+     /* clear rx fifo */
+     timeout = SPRD_TIMEOUT;

drivers/tty/serial/sprd_serial.c line 327

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+     while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
+             serial_in(port, SPRD_RXD);
+
+     /* clear tx fifo */
+     timeout = SPRD_TIMEOUT;
+     while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
+             cpu_relax();
+
+     /* clear interrupt */
+     serial_out(port, SPRD_IEN, 0x0);

                                   ^^^
                                 just 0

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+     serial_out(port, SPRD_ICLR, ~0);
+
+     /* allocate irq */
+     sp = container_of(port, struct sprd_uart_port, port);

drivers/tty/serial/sprd_serial.c line 341

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+     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, ret=%d\n",
+                     port->irq, ret);
+             return ret;
+     }
+     ctrl1 = serial_in(port, SPRD_CTL1);
+     ctrl1 |= 0x3e00 | THLD_RX_FULL;

                 ^^^^^

What is this magic number?

drivers/tty/serial/sprd_serial.c line 345

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+     serial_out(port, SPRD_CTL1, ctrl1);
+
+     /* enable interrupt */
+     spin_lock(&port->lock);

        spin_lock_irqsave(&port->lock, flags);

drivers/tty/serial/sprd_serial.c line 349

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+     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);

        spin_unlock_irqrestore(&port->lock, flags);

drivers/tty/serial/sprd_serial.c line 356

Quoted 7 lines

drivers/tty/serial/sprd_serial.c new file +7 -0

+
+     return 0;
+}
+
+static void sprd_shutdown(struct uart_port *port)
+{
+     serial_out(port, SPRD_IEN, 0x0);

                                   ^^^
                                 just 0

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+     serial_out(port, SPRD_ICLR, ~0);
+     devm_free_irq(port->dev, port->irq, port);
+}
+

drivers/tty/serial/sprd_serial.c line 370

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+static void sprd_set_termios(struct uart_port *port,
+                                 struct ktermios *termios,
+                                 struct ktermios *old)
+{
+     unsigned int baud, quot;
+     unsigned int lcr, fc;
+     unsigned long flags;
+
+     /* ask the core to calculate the divisor for us */
+     baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);

^^^^ ^^^^^^
mabye derive these from uartclk?

drivers/tty/serial/sprd_serial.c line 376

Quoted 7 lines

drivers/tty/serial/sprd_serial.c new file +6 -0

+
+     quot = (unsigned int)((port->uartclk + baud / 2) / baud);
+
+     /* set data length */
+     lcr = serial_in(port, SPRD_LCR);
+     lcr &= ~SPRD_LCR_DATA_LEN;

What bits are being preserved in SPRD_LCR that you need to read the current value? IOW, why can't SPRD_LCR be defined only by the termios c_cflag? Like,

        lcr = 0;

Quoted 33 lines

drivers/tty/serial/sprd_serial.c new file +33 -0

+     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;
+     termios->c_cflag &= ~CMSPAR;    /* no support mark/space */
+     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;
+     }

drivers/tty/serial/sprd_serial.c line 419

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     spin_lock_irqsave(&port->lock, flags);
+
+     /* 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))

        if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))

Because if IGNBRK is set and a BRK is received, sprd_rx() should operate like this:
/* - RESULT - */
lsr = serial_in(SPRD_LSR) /* lsr = SPRD_LSR_BI */
ch = serial_in(SPRD_RXD) /* ch = 0 */

lsr & SPRD_LSR_BI ? yes
handle_lsr_errors(lsr, flag)

lsr &= read_status_mask /* lsr = SPRD_LSR_BI */
flag = TTY_BREAK

uart_insert_char(lsr, ch, flag)
lsr & ignore_status_mask == 0? no /* ch _not_ inserted */

Quoted 109 lines

drivers/tty/serial/sprd_serial.c new file +109 -0

+             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);
+
+     spin_unlock_irqrestore(&port->lock, flags);
+
+     /* Don't rewrite B0 */
+     if (tty_termios_baud_rate(termios))
+             tty_termios_encode_baud_rate(termios, baud, baud);
+}
+
+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 (ser->type != PORT_SPRD)
+             return -EINVAL;
+     if (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);
+}

drivers/tty/serial/sprd_serial.c line 538

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+static void sprd_console_write(struct console *co, const char *s,
+                                   unsigned int count)
+{
+     struct uart_port *port = &sprd_port[co->index]->port;
+     int locked = 1;
+     unsigned long flags;
+
+     if (oops_in_progress)
+             locked = spin_trylock(&port->lock);

        if (port->sysrq)
                locked = 0;
        else if (oops_in_progress)
                locked = spin_trylock_irqsave(&port->lock, flags);

Quoted 118 lines

drivers/tty/serial/sprd_serial.c new file +118 -0

+     else
+             spin_lock_irqsave(&port->lock, flags);
+
+     uart_console_write(port, s, count, sprd_console_putchar);
+
+     /* wait for transmitter to become empty */
+     wait_for_xmitr(port);
+
+     if (locked)
+             spin_unlock_irqrestore(&port->lock, flags);
+}
+
+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 (co->index >= UART_NR_MAX || co->index < 0)
+             co->index = 0;
+
+     port = &sprd_port[co->index]->port;
+     if (port == NULL) {
+             pr_info("serial 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)
+{
+     unsigned int timeout = SPRD_TIMEOUT;
+
+     while (timeout-- &&
+                !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
+             cpu_relax();
+
+     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 = 0,
+     .minor = 0,
+     .nr = UART_NR_MAX,
+     .cons = SPRD_CONSOLE,
+};
+
+static int sprd_probe_dt_alias(int index, struct device *dev)
+{
+     struct device_node *np;
+     static bool seen_dev_with_alias;
+     static bool seen_dev_without_alias;
+     int ret = index;
+
+     if (!IS_ENABLED(CONFIG_OF))
+             return ret;
+
+     np = dev->of_node;
+     if (!np)
+             return ret;
+
+     ret = of_alias_get_id(np, "serial");
+     if (IS_ERR_VALUE(ret)) {
+             seen_dev_without_alias = true;
+             ret = index;
+     } else {
+             seen_dev_with_alias = true;
+             if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
+                     dev_warn(dev, "requested serial port %d  not available.\n", ret);

drivers/tty/serial/sprd_serial.c line 662

Quoted 6 lines

drivers/tty/serial/sprd_serial.c new file +6 -0

+                     ret = index;
+             }
+     }
+
+     if (seen_dev_with_alias && seen_dev_without_alias)
+             dev_warn(dev, "aliased and non-aliased serial devices found in device tree. Serial port enumeration may be unpredictable.\n");

Is this necessary? Why does a user want to know this?

drivers/tty/serial/sprd_serial.c line 674

Quoted 13 lines

drivers/tty/serial/sprd_serial.c new file +12 -0

+
+     return ret;
+}
+
+static int sprd_remove(struct platform_device *dev)
+{
+     struct sprd_uart_port *sup = platform_get_drvdata(dev);
+     bool busy = false;
+     int i;
+
+     if (sup)
+             uart_remove_one_port(&sprd_uart_driver, &sup->port);

see comment in sprd_probe()

        if (sup) {
                uart_remove_one_port();
                sprd_port[sup->line] = NULL;
                sprd_ports--;
        }

        if (!sprd_ports)
                uart_unregister_driver();

Quoted 35 lines

drivers/tty/serial/sprd_serial.c new file +35 -0

+
+     for (i = 0; i < ARRAY_SIZE(sprd_port); i++)
+             if (sprd_port[i] == sup)
+                     sprd_port[i] = NULL;
+             else if (sprd_port[i])
+                     busy = true;
+
+     if (!busy)
+             uart_unregister_driver(&sprd_uart_driver);
+
+     return 0;
+}
+
+static int sprd_probe(struct platform_device *pdev)
+{
+     struct resource *res;
+     struct uart_port *up;
+     struct clk *clk;
+     int irq;
+     int index;
+     int ret;
+
+     for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
+             if (sprd_port[index] == NULL)
+                     break;
+
+     if (index == ARRAY_SIZE(sprd_port))
+             return -EBUSY;
+
+     index = sprd_probe_dt_alias(index, &pdev->dev);
+
+     sprd_port[index] = devm_kzalloc(&pdev->dev,
+             sizeof(*sprd_port[index]), GFP_KERNEL);
+     if (!sprd_port[index])
+             return -ENOMEM;

drivers/tty/serial/sprd_serial.c line 719

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     up = &sprd_port[index]->port;
+     up->dev = &pdev->dev;
+     up->line = index;
+     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;

                    ^^^^^^^^^
                    UPF_BOOT_AUTOCONF

sparse will catch errors like this. See Documentation/sparse.txt

Quoted 14 lines

drivers/tty/serial/sprd_serial.c new file +13 -0

+
+     clk = devm_clk_get(&pdev->dev, NULL);
+     if (!IS_ERR(clk))
+             up->uartclk = clk_get_rate(clk);
+
+     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+     if (!res) {
+             dev_err(&pdev->dev, "not provide mem resource\n");
+             return -ENODEV;
+     }
+     up->mapbase = res->start;
+     up->membase = devm_ioremap_resource(&pdev->dev, res);
+     if (IS_ERR(up->membase))

drivers/tty/serial/sprd_serial.c line 742

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+             return PTR_ERR(up->membase);
+
+     irq = platform_get_irq(pdev, 0);
+     if (irq < 0) {
+             dev_err(&pdev->dev, "not provide irq resource\n");
+             return -ENODEV;
+     }
+     up->irq = irq;
+
+     if (!sprd_uart_driver.state) {

             ^^^^^^^^^^^^^^^^^^^^^^

I know Rob said this was ok, but it's not.

Just use a global counter.

        if (!sprd_ports) {

drivers/tty/serial/sprd_serial.c line 749

Quoted 7 lines

drivers/tty/serial/sprd_serial.c new file +7 -0

+             ret = uart_register_driver(&sprd_uart_driver);
+             if (ret < 0) {
+                     pr_err("Failed to register SPRD-UART driver\n");
+                     return ret;
+             }
+     }
+

        sprd_ports++;

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+     ret = uart_add_one_port(&sprd_uart_driver, up);
+     if (ret) {
+             sprd_port[index] = NULL;
+             sprd_remove(pdev);
+     }
+
+     platform_set_drvdata(pdev, up);
+
+     return ret;
+}

drivers/tty/serial/sprd_serial.c line 764

Quoted 5 lines

drivers/tty/serial/sprd_serial.c new file +5 -0

+
+static int sprd_suspend(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;

I'm a little confused regarding the port indexing; is platform_device->id == line ? Where did that happen?

Quoted 46 lines

drivers/tty/serial/sprd_serial.c new file +37 -0

+
+     uart_suspend_port(&sprd_uart_driver, port);
+
+     return 0;
+}
+
+static int sprd_resume(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;
+
+     uart_resume_port(&sprd_uart_driver, port);
+
+     return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
+
+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,
+     .driver         = {
+             .name   = "sprd_serial",
+             .of_match_table = of_match_ptr(serial_ids),
+             .pm     = &sprd_pm_ops,
+     },
+};
+
+module_platform_driver(sprd_platform_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");

include/uapi/linux/serial_core.h +0 -0

index c172180..7e6eb39 100644
@@ -248,4 +248,7 @@
 /* MESON */
 #define PORT_MESON   109
 

include/uapi/linux/serial_core.h line 254

Quoted 5 lines

include/uapi/linux/serial_core.h +3 -0

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

Hi, Peter

Many thanks to you for reviewing so carefully and giving us so many suggestions and so clear explanations.

I'll address all of your comments and send an updated patch soon.

On Fri, Jan 23, 2015 at 11:57 AM, Peter Hurley <[email protected]> wrote:

Quoted 4 lines

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+static void sprd_set_termios(struct uart_port *port,
+                                 struct ktermios *termios,
+                                 struct ktermios *old)
+{

Quoted 8 lines

drivers/tty/serial/sprd_serial.c line 370

Quoted 6 lines

drivers/tty/serial/sprd_serial.c new file +6 -0

+     unsigned int baud, quot;
+     unsigned int lcr, fc;
+     unsigned long flags;
+
+     /* ask the core to calculate the divisor for us */
+     baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);

^^^^ ^^^^^^
mabye derive these from uartclk?

I'm afraid I can't understand very clearly, Could you explain more details please?

Quoted 35 lines

Quoted 22 lines

drivers/tty/serial/sprd_serial.c new file +22 -0

+static int sprd_probe(struct platform_device *pdev)
+{
+     struct resource *res;
+     struct uart_port *up;
+     struct clk *clk;
+     int irq;
+     int index;
+     int ret;
+
+     for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
+             if (sprd_port[index] == NULL)
+                     break;
+
+     if (index == ARRAY_SIZE(sprd_port))
+             return -EBUSY;
+
+     index = sprd_probe_dt_alias(index, &pdev->dev);
+
+     sprd_port[index] = devm_kzalloc(&pdev->dev,
+             sizeof(*sprd_port[index]), GFP_KERNEL);
+     if (!sprd_port[index])
+             return -ENOMEM;

drivers/tty/serial/sprd_serial.c line 719

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     up = &sprd_port[index]->port;
+     up->dev = &pdev->dev;
+     up->line = index;
+     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;

                    ^^^^^^^^^
                    UPF_BOOT_AUTOCONF

Quoted 1 line

sparse will catch errors like this. See Documentation/sparse.txt

you mean we should use UPF_BOOT_AUTOCONF, right?

Quoted 8 lines

drivers/tty/serial/sprd_serial.c line 764

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+static int sprd_suspend(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;

I'm a little confused regarding the port indexing; is platform_device->id == line ? Where did that happen?

Oh, I'll change to assign platform_device->id with port->line in probe()

Quoted 14 lines

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +2 -0

+
+     uart_suspend_port(&sprd_uart_driver, port);

drivers/tty/serial/sprd_serial.c line 776

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     return 0;
+}
+
+static int sprd_resume(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;
+
+     uart_resume_port(&sprd_uart_driver, port);

Quoted 1 line

Quoted 1 line

+ return 0;

Quoted 4 lines · Lyra Zhang

Hi, Peter

Many thanks to you for reviewing so carefully and giving us so many suggestions and so clear explanations.

:)

Quoted 3 lines

I'll address all of your comments and send an updated patch soon.

On Fri, Jan 23, 2015 at 11:57 AM, Peter Hurley <[email protected]> wrote:

[...]

Quoted 13 lines

Quoted 4 lines

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+static void sprd_set_termios(struct uart_port *port,
+                                 struct ktermios *termios,
+                                 struct ktermios *old)
+{

Quoted 8 lines

drivers/tty/serial/sprd_serial.c line 370

Quoted 6 lines

drivers/tty/serial/sprd_serial.c new file +6 -0

+     unsigned int baud, quot;
+     unsigned int lcr, fc;
+     unsigned long flags;
+
+     /* ask the core to calculate the divisor for us */
+     baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);

^^^^ ^^^^^^
mabye derive these from uartclk?

Quoted 2 lines

I'm afraid I can't understand very clearly, Could you explain more details please?

Is the fixed clock divider == 8 and the uartclk == 26000000 ? If so,

        baud = uartclk / 8 = 3250000

I see now this is clamping baud inside the maximum, so this is fine. Please disregard my comment.

[...]

Quoted 35 lines

Quoted 35 lines

Quoted 22 lines

drivers/tty/serial/sprd_serial.c new file +22 -0

+static int sprd_probe(struct platform_device *pdev)
+{
+     struct resource *res;
+     struct uart_port *up;
+     struct clk *clk;
+     int irq;
+     int index;
+     int ret;
+
+     for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
+             if (sprd_port[index] == NULL)
+                     break;
+
+     if (index == ARRAY_SIZE(sprd_port))
+             return -EBUSY;
+
+     index = sprd_probe_dt_alias(index, &pdev->dev);
+
+     sprd_port[index] = devm_kzalloc(&pdev->dev,
+             sizeof(*sprd_port[index]), GFP_KERNEL);
+     if (!sprd_port[index])
+             return -ENOMEM;

drivers/tty/serial/sprd_serial.c line 719

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     up = &sprd_port[index]->port;
+     up->dev = &pdev->dev;
+     up->line = index;
+     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;

                    ^^^^^^^^^
                    UPF_BOOT_AUTOCONF

Quoted 3 lines

Quoted 1 line

sparse will catch errors like this. See Documentation/sparse.txt

you mean we should use UPF_BOOT_AUTOCONF, right?

Yes. Only UPF_* flag definitions should be used with the uart_port.flags field.

My comment regarding the sparse tool and documentation is because the flags field and UPF_* definitions use a type mechanism to generate warnings using the sparse tool if regular integer values are used with the flags field.

The type mechanism was specifically introduced to catch using ASYNC_* definitions with the uart_port.flags field.

[...]

Quoted 10 lines

Quoted 8 lines

drivers/tty/serial/sprd_serial.c line 764

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +4 -0

+static int sprd_suspend(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;

I'm a little confused regarding the port indexing; is platform_device->id == line ? Where did that happen?

Oh, I'll change to assign platform_device->id with port->line in probe()

I apologize; I should have made my comment clearer.

The ->id should not be assigned.

Replace

        int id = to_platform_device(dev)->id;
        struct uart_port *port = &sprd_port[id]->port;

        uart_suspend_port(&sprd_uart_driver, port);

with

        struct sprd_uart_port *sup = dev_get_drvdata(dev);

        uart_suspend_port(&sprd_uart_driver, &sup->port);

I know it's not obvious but platform_get/set_drvdata() is really dev_get/set_drvdata() using the embedded struct device dev.

Quoted 14 lines

Quoted 14 lines

Quoted 4 lines

drivers/tty/serial/sprd_serial.c new file +2 -0

+
+     uart_suspend_port(&sprd_uart_driver, port);

drivers/tty/serial/sprd_serial.c line 776

Quoted 10 lines

drivers/tty/serial/sprd_serial.c new file +10 -0

+
+     return 0;
+}
+
+static int sprd_resume(struct device *dev)
+{
+     int id = to_platform_device(dev)->id;
+     struct uart_port *port = &sprd_port[id]->port;
+
+     uart_resume_port(&sprd_uart_driver, port);

same here

Quoted 1 line

Quoted 1 line

Quoted 1 line

+ return 0;