serial: driver for Conexant Digicolor USART

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 582 insertions, 0 deletions

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index c79b43cd6014..96ec6cfd74e8 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1549,6 +1549,21 @@ config SERIAL_FSL_LPUART_CONSOLE
 	  If you have enabled the lpuart serial port on the Freescale SoCs,
 	  you can make it the console by answering Y to this option.
 
+config SERIAL_CONEXANT_DIGICOLOR
+	tristate "Conexant Digicolor CX92xxx USART serial port support"
+	depends on OF
+	select SERIAL_CORE
+	help
+	  Support for the on-chip USART on Conexant Digicolor SoCs.
+
+config SERIAL_CONEXANT_DIGICOLOR_CONSOLE
+	bool "Console on Conexant Digicolor serial port"
+	depends on SERIAL_CONEXANT_DIGICOLOR=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  If you have enabled the USART serial port on Conexant Digicolor
+	  SoCs, you can make it the console by answering Y to this option.
+
 config SERIAL_ST_ASC
 	tristate "ST ASC serial port support"
 	select SERIAL_CORE
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 9a548acf5fdc..770a19bb7fcb 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
 obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
 obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
 obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o
+obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR)	+= digicolor-usart.o
 obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
 
 # GPIOLIB helpers for modem control lines
diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
new file mode 100644
index 000000000000..09ce0b3764e2
--- /dev/null
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -0,0 +1,563 @@
+/*
+ *  Driver for Conexant Digicolor serial ports (USART)
+ *
+ * Author: Baruch Siach <baruch@tkos.co.il>
+ *
+ * Copyright (C) 2014 Paradox Innovation Ltd.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/console.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+
+#define UA_ENABLE			0x00
+#define UA_ENABLE_ENABLE		BIT(0)
+
+#define UA_CONTROL			0x01
+#define UA_CONTROL_RX_ENABLE		BIT(0)
+#define UA_CONTROL_TX_ENABLE		BIT(1)
+#define UA_CONTROL_SOFT_RESET		BIT(2)
+
+#define UA_STATUS			0x02
+#define UA_STATUS_PARITY_ERR		BIT(0)
+#define UA_STATUS_FRAME_ERR		BIT(1)
+#define UA_STATUS_OVERRUN_ERR		BIT(2)
+#define UA_STATUS_TX_READY		BIT(6)
+
+#define UA_CONFIG			0x03
+#define UA_CONFIG_CHAR_LEN		BIT(0)
+#define UA_CONFIG_STOP_BITS		BIT(1)
+#define UA_CONFIG_PARITY		BIT(2)
+#define UA_CONFIG_ODD_PARITY		BIT(4)
+
+#define UA_EMI_REC			0x04
+
+#define UA_HBAUD_LO			0x08
+#define UA_HBAUD_HI			0x09
+
+#define UA_STATUS_FIFO			0x0a
+#define UA_STATUS_FIFO_RX_EMPTY		BIT(2)
+#define UA_STATUS_FIFO_RX_INT_ALMOST	BIT(3)
+#define UA_STATUS_FIFO_TX_FULL		BIT(4)
+#define UA_STATUS_FIFO_TX_INT_ALMOST	BIT(7)
+
+#define UA_CONFIG_FIFO			0x0b
+#define UA_CONFIG_FIFO_RX_THRESH	7
+#define UA_CONFIG_FIFO_RX_FIFO_MODE	BIT(3)
+#define UA_CONFIG_FIFO_TX_FIFO_MODE	BIT(7)
+
+#define UA_INTFLAG_CLEAR		0x1c
+#define UA_INTFLAG_SET			0x1d
+#define UA_INT_ENABLE			0x1e
+#define UA_INT_STATUS			0x1f
+
+#define UA_INT_TX			BIT(0)
+#define UA_INT_RX			BIT(1)
+
+#define DIGICOLOR_USART_NR		3
+
+/*
+ * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
+ * only produced when the FIFO is filled more than a certain configurable
+ * threshold. Unfortunately, there is no way to set this threshold below half
+ * FIFO. This means that we must periodically poll the FIFO status register to
+ * see whether there are waiting Rx bytes.
+ */
+
+struct digicolor_port {
+	struct uart_port port;
+	struct delayed_work rx_poll_work;
+};
+
+static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
+
+static bool digicolor_uart_tx_full(struct uart_port *port)
+{
+	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
+		  UA_STATUS_FIFO_TX_FULL);
+}
+
+static bool digicolor_uart_rx_empty(struct uart_port *port)
+{
+	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
+		  UA_STATUS_FIFO_RX_EMPTY);
+}
+
+static void digicolor_uart_stop_tx(struct uart_port *port)
+{
+	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
+
+	int_enable &= ~UA_INT_TX;
+	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
+}
+
+static void digicolor_uart_start_tx(struct uart_port *port)
+{
+	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
+
+	int_enable |= UA_INT_TX;
+	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
+}
+
+static void digicolor_uart_stop_rx(struct uart_port *port)
+{
+	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
+
+	int_enable &= ~UA_INT_RX;
+	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
+}
+
+static void digicolor_rx_poll(struct work_struct *work)
+{
+	struct digicolor_port *dp =
+		container_of(to_delayed_work(work),
+			     struct digicolor_port, rx_poll_work);
+
+	if (!digicolor_uart_rx_empty(&dp->port))
+		/* force RX interrupt */
+		writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
+
+	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
+}
+
+static void digicolor_uart_rx(struct uart_port *port)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	while (1) {
+		u8 status, ch;
+		unsigned int ch_flag;
+
+		if (digicolor_uart_rx_empty(port))
+			break;
+
+		ch = readb_relaxed(port->membase + UA_EMI_REC);
+		status = readb_relaxed(port->membase + UA_STATUS);
+
+		port->icount.rx++;
+		ch_flag = TTY_NORMAL;
+
+		if (status) {
+			if (status & UA_STATUS_PARITY_ERR)
+				port->icount.parity++;
+			else if (status & UA_STATUS_FRAME_ERR)
+				port->icount.frame++;
+			else if (status & UA_STATUS_OVERRUN_ERR)
+				port->icount.overrun++;
+
+			status &= port->read_status_mask;
+
+			if (status & UA_STATUS_PARITY_ERR)
+				ch_flag = TTY_PARITY;
+			else if (status & UA_STATUS_FRAME_ERR)
+				ch_flag = TTY_FRAME;
+			else if (status & UA_STATUS_OVERRUN_ERR)
+				ch_flag = TTY_OVERRUN;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
+		if (status & port->ignore_status_mask)
+			continue;
+
+		uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
+				 ch_flag);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	tty_flip_buffer_push(&port->state->port);
+}
+
+static void digicolor_uart_tx(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned long flags;
+
+	if (digicolor_uart_tx_full(port))
+		return;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (port->x_char) {
+		writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
+		port->icount.tx++;
+		port->x_char = 0;
+		goto out;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		digicolor_uart_stop_tx(port);
+		goto out;
+	}
+
+	while (!uart_circ_empty(xmit)) {
+		writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+
+		if (digicolor_uart_tx_full(port))
+			break;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+out:
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+	u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
+
+	writeb_relaxed(UA_INT_RX | UA_INT_TX,
+		       port->membase + UA_INTFLAG_CLEAR);
+
+	if (int_status & UA_INT_RX)
+		digicolor_uart_rx(port);
+	if (int_status & UA_INT_TX)
+		digicolor_uart_tx(port);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
+{
+	u8 status = readb_relaxed(port->membase + UA_STATUS);
+
+	return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS;
+}
+
+static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static void digicolor_uart_break_ctl(struct uart_port *port, int state)
+{
+}
+
+static int digicolor_uart_startup(struct uart_port *port)
+{
+	struct digicolor_port *dp =
+		container_of(port, struct digicolor_port, port);
+
+	writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
+	writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
+	writeb_relaxed(0, port->membase + UA_CONTROL);
+
+	writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
+		       | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
+		       port->membase + UA_CONFIG_FIFO);
+	writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
+		       port->membase + UA_STATUS_FIFO);
+	writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
+		       port->membase + UA_CONTROL);
+	writeb_relaxed(UA_INT_TX | UA_INT_RX,
+		       port->membase + UA_INT_ENABLE);
+
+	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
+
+	return 0;
+}
+
+static void digicolor_uart_shutdown(struct uart_port *port)
+{
+	struct digicolor_port *dp =
+		container_of(port, struct digicolor_port, port);
+
+	writeb_relaxed(0, port->membase + UA_ENABLE);
+	cancel_delayed_work_sync(&dp->rx_poll_work);
+}
+
+static void digicolor_uart_set_termios(struct uart_port *port,
+				       struct ktermios *termios,
+				       struct ktermios *old)
+{
+	unsigned int baud, divisor;
+	u8 config = 0;
+	unsigned long flags;
+
+	/* Mask termios capabilities we don't support */
+	termios->c_cflag &= ~CMSPAR;
+	termios->c_iflag &= ~(BRKINT | IGNBRK);
+
+	/* Limit baud rates so that we don't need the fractional divider */
+	baud = uart_get_baud_rate(port, termios, old,
+				  port->uartclk / (0x10000*16),
+				  port->uartclk / 256);
+	divisor = uart_get_divisor(port, baud) - 1;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS7:
+		break;
+	case CS8:
+	default:
+		config |= UA_CONFIG_CHAR_LEN;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		config |= UA_CONFIG_STOP_BITS;
+
+	if (termios->c_cflag & PARENB) {
+		config |= UA_CONFIG_PARITY;
+		if (termios->c_cflag & PARODD)
+			config |= UA_CONFIG_ODD_PARITY;
+	}
+
+	/* Set read status mask */
+	port->read_status_mask = UA_STATUS_OVERRUN_ERR;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= UA_STATUS_PARITY_ERR
+			| UA_STATUS_FRAME_ERR;
+
+	/* Set status ignore mask */
+	port->ignore_status_mask = 0;
+	if (!(termios->c_cflag & CREAD))
+		port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
+			| UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	writeb_relaxed(config, port->membase + UA_CONFIG);
+	writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
+	writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *digicolor_uart_type(struct uart_port *port)
+{
+	return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
+}
+
+static void digicolor_uart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_DIGICOLOR;
+}
+
+static void digicolor_uart_release_port(struct uart_port *port)
+{
+}
+
+static int digicolor_uart_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static const struct uart_ops digicolor_uart_ops = {
+	.tx_empty	= digicolor_uart_tx_empty,
+	.set_mctrl	= digicolor_uart_set_mctrl,
+	.get_mctrl	= digicolor_uart_get_mctrl,
+	.stop_tx	= digicolor_uart_stop_tx,
+	.start_tx	= digicolor_uart_start_tx,
+	.stop_rx	= digicolor_uart_stop_rx,
+	.break_ctl	= digicolor_uart_break_ctl,
+	.startup	= digicolor_uart_startup,
+	.shutdown	= digicolor_uart_shutdown,
+	.set_termios	= digicolor_uart_set_termios,
+	.type		= digicolor_uart_type,
+	.config_port	= digicolor_uart_config_port,
+	.release_port	= digicolor_uart_release_port,
+	.request_port	= digicolor_uart_request_port,
+};
+
+static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
+{
+	while (digicolor_uart_tx_full(port))
+		cpu_relax();
+
+	writeb_relaxed(ch, port->membase + UA_EMI_REC);
+}
+
+static void digicolor_uart_console_write(struct console *co, const char *c,
+					 unsigned n)
+{
+	struct uart_port *port = digicolor_ports[co->index];
+	u8 status;
+	unsigned long flags;
+	int locked = 1;
+
+	if (port->sysrq || oops_in_progress)
+		locked = spin_trylock_irqsave(&port->lock, flags);
+	else
+		spin_lock_irqsave(&port->lock, flags);
+
+	uart_console_write(port, c, n, digicolor_uart_console_putchar);
+
+	if (locked)
+		spin_unlock_irqrestore(&port->lock, flags);
+
+	/* Wait for transmitter to become empty */
+	do {
+		status = readb_relaxed(port->membase + UA_STATUS);
+	} while ((status & UA_STATUS_TX_READY) == 0);
+}
+
+static int digicolor_uart_console_setup(struct console *co, char *options)
+{
+	int baud = 115200, bits = 8, parity = 'n', flow = 'n';
+	struct uart_port *port;
+
+	if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
+		return -EINVAL;
+
+	port = digicolor_ports[co->index];
+	if (!port)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct console digicolor_console = {
+	.name	= "ttyS",
+	.device	= uart_console_device,
+	.write	= digicolor_uart_console_write,
+	.setup	= digicolor_uart_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+};
+
+static struct uart_driver digicolor_uart = {
+	.driver_name	= "digicolor-usart",
+	.dev_name	= "ttyS",
+	.nr		= DIGICOLOR_USART_NR,
+};
+
+static int digicolor_uart_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	int ret, index;
+	struct digicolor_port *dp;
+	struct resource *res;
+	struct clk *uart_clk;
+
+	if (!np) {
+		dev_err(&pdev->dev, "Missing device tree node\n");
+		return -ENXIO;
+	}
+
+	index = of_alias_get_id(np, "serial");
+	if (index < 0 || index >= DIGICOLOR_USART_NR)
+		return -EINVAL;
+
+	dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
+	if (!dp)
+		return -ENOMEM;
+
+	uart_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(uart_clk))
+		return PTR_ERR(uart_clk);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dp->port.mapbase = res->start;
+	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dp->port.membase))
+		return PTR_ERR(dp->port.membase);
+
+	dp->port.irq = platform_get_irq(pdev, 0);
+	if (IS_ERR_VALUE(dp->port.irq))
+		return dp->port.irq;
+
+	dp->port.iotype = UPIO_MEM;
+	dp->port.uartclk = clk_get_rate(uart_clk);
+	dp->port.fifosize = 16;
+	dp->port.dev = &pdev->dev;
+	dp->port.ops = &digicolor_uart_ops;
+	dp->port.line = index;
+	dp->port.type = PORT_DIGICOLOR;
+	spin_lock_init(&dp->port.lock);
+
+	digicolor_ports[index] = &dp->port;
+	platform_set_drvdata(pdev, &dp->port);
+
+	INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
+
+	ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
+			       dev_name(&pdev->dev), &dp->port);
+	if (ret)
+		return ret;
+
+	return uart_add_one_port(&digicolor_uart, &dp->port);
+}
+
+static int digicolor_uart_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&digicolor_uart, port);
+
+	return 0;
+}
+
+static const struct of_device_id digicolor_uart_dt_ids[] = {
+	{ .compatible = "cnxt,cx92755-usart", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
+
+static struct platform_driver digicolor_uart_platform = {
+	.driver = {
+		.name		= "digicolor-usart",
+		.of_match_table	= of_match_ptr(digicolor_uart_dt_ids),
+	},
+	.probe	= digicolor_uart_probe,
+	.remove	= digicolor_uart_remove,
+};
+
+static int __init digicolor_uart_init(void)
+{
+	int ret;
+
+	if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
+		digicolor_uart.cons = &digicolor_console;
+		digicolor_console.data = &digicolor_uart;
+	}
+
+	ret = uart_register_driver(&digicolor_uart);
+	if (ret)
+		return ret;
+
+	return platform_driver_register(&digicolor_uart_platform);
+}
+module_init(digicolor_uart_init);
+
+static void __exit digicolor_uart_exit(void)
+{
+	platform_driver_unregister(&digicolor_uart_platform);
+	uart_unregister_driver(&digicolor_uart);
+}
+module_exit(digicolor_uart_exit);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index c17218094f18..9124e837c181 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -248,4 +248,7 @@
 /* MESON */
 #define PORT_MESON	109
 
+/* Conexant Digicolor */
+#define PORT_DIGICOLOR	110
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */