[RFC PATCH 04/10] serial: mps2-uart: add MPS2 UART driver

Vladimir Murzin
2015-11-25T10:33:35Z

This driver adds support to the UART controller found on ARM MPS2
platform.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
drivers/tty/serial/Kconfig | 12 +
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/mps2-uart.c | 596 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/serial_core.h | 3 +
4 files changed, 612 insertions(+)
create mode 100644 drivers/tty/serial/mps2-uart.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 1aec440..b47f8fc 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1473,6 +1473,18 @@ config SERIAL_EFM32_UART
This driver support the USART and UART ports on
Energy Micro's efm32 SoCs.

+config SERIAL_MPS2_UART_CONSOLE
+ bool "MPS2 UART console support"
+ depends on SERIAL_MPS2_UART
+ select SERIAL_CORE_CONSOLE
+
+config SERIAL_MPS2_UART
+ tristate "MPS2 UART port"
+ depends on ARM || COMPILE_TEST
+ select SERIAL_CORE
+ help
+ This driver support the UART ports on ARM MPS2.
+
config SERIAL_EFM32_UART_CONSOLE
bool "EFM32 UART/USART console support"
depends on SERIAL_EFM32_UART=y
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 5ab4111..7f589f5 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR) += digicolor-usart.o
obj-$(CONFIG_SERIAL_MEN_Z135) += men_z135_uart.o
obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
obj-$(CONFIG_SERIAL_STM32) += stm32-usart.o
+obj-$(CONFIG_SERIAL_MPS2_UART) += mps2-uart.o

# GPIOLIB helpers for modem control lines
obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
new file mode 100644
index 0000000..00e882e
--- /dev/null
+++ b/drivers/tty/serial/mps2-uart.c
@@ -0,0 +1,596 @@
+/*
+ * Copyright (C) 2015 ARM Limited
+ *
+ * Author: Vladimir Murzin <vladimir.murzin@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * TODO: support for SysRq
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/tty_flip.h>
+#include <linux/types.h>
+
+#define SERIAL_NAME "ttyMPS"
+#define DRIVER_NAME "mps2-uart"
+#define MAKE_NAME(x) (DRIVER_NAME # x)
+
+#define UARTn_DATA 0x0
+
+#define UARTn_STATE 0x4
+#define UARTn_STATE_TX_FULL BIT(0)
+#define UARTn_STATE_RX_FULL BIT(1)
+#define UARTn_STATE_TX_OVERRUN BIT(2)
+#define UARTn_STATE_RX_OVERRUN BIT(3)
+
+#define UARTn_CTRL 0x8
+#define UARTn_CTRL_TX_ENABLE BIT(0)
+#define UARTn_CTRL_RX_ENABLE BIT(1)
+#define UARTn_CTRL_TX_INT_ENABLE BIT(2)
+#define UARTn_CTRL_RX_INT_ENABLE BIT(3)
+#define UARTn_CTRL_TX_OVERRUN_INT_ENABLE BIT(4)
+#define UARTn_CTRL_RX_OVERRUN_INT_ENABLE BIT(5)
+
+#define UARTn_INT 0xc
+#define UARTn_INT_TX BIT(0)
+#define UARTn_INT_RX BIT(1)
+#define UARTn_INT_TX_OVERRUN BIT(2)
+#define UARTn_INT_RX_OVERRUN BIT(3)
+
+#define UARTn_BAUDDIV 0x10
+#define UARTn_BAUDDIV_MASK GENMASK(20, 0)
+
+#define MPS2_MAX_PORTS 3
+
+struct mps2_uart_port {
+ struct uart_port port;
+ struct clk *clk;
+ unsigned int tx_irq;
+ unsigned int rx_irq;
+};
+
+static inline struct mps2_uart_port *to_mps2_port(struct uart_port *port)
+{
+ return container_of(port, struct mps2_uart_port, port);
+}
+
+static void mps2_uart_write8(struct uart_port *port, u8 val, unsigned off)
+{
+ struct mps2_uart_port *mps_port = to_mps2_port(port);
+
+ writeb(val, mps_port->port.membase + off);
+}
+
+static u8 mps2_uart_read8(struct uart_port *port, unsigned off)
+{
+ struct mps2_uart_port *mps_port = to_mps2_port(port);
+
+ return readb(mps_port->port.membase + off);
+}
+
+static void mps2_uart_write32(struct uart_port *port, u32 val, unsigned off)
+{
+ struct mps2_uart_port *mps_port = to_mps2_port(port);
+
+ writel_relaxed(val, mps_port->port.membase + off);
+}
+
+static unsigned int mps2_uart_tx_empty(struct uart_port *port)
+{
+ u8 status = mps2_uart_read8(port, UARTn_STATE);
+
+ return (status & UARTn_STATE_TX_FULL) ? 0 : TIOCSER_TEMT;
+}
+
+static void mps2_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int mps2_uart_get_mctrl(struct uart_port *port)
+{
+ return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
+}
+
+static void mps2_uart_stop_tx(struct uart_port *port)
+{
+ u8 control = mps2_uart_read8(port, UARTn_CTRL);
+
+ control &= ~(UARTn_CTRL_TX_ENABLE |
+ UARTn_CTRL_TX_INT_ENABLE |
+ UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+}
+
+static void mps2_uart_tx_chars(struct uart_port *port)
+{
+ struct circ_buf *xmit = &port->state->xmit;
+
+ while (!(mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)) {
+ if (port->x_char) {
+ mps2_uart_write8(port, port->x_char, UARTn_DATA);
+ port->x_char = 0;
+ port->icount.tx++;
+ continue;
+ }
+
+ if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+ break;
+
+ mps2_uart_write8(port, xmit->buf[xmit->tail], UARTn_DATA);
+ xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+ port->icount.tx++;
+ }
+
+ if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(port);
+
+ if (uart_circ_empty(xmit))
+ mps2_uart_stop_tx(port);
+}
+
+static void mps2_uart_start_tx(struct uart_port *port)
+{
+ u8 control = mps2_uart_read8(port, UARTn_CTRL);
+
+ control |= (UARTn_CTRL_TX_ENABLE |
+ UARTn_CTRL_TX_INT_ENABLE |
+ UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+ mps2_uart_tx_chars(port);
+}
+
+static void mps2_uart_stop_rx(struct uart_port *port)
+{
+ u8 control = mps2_uart_read8(port, UARTn_CTRL);
+
+ control &= ~(UARTn_CTRL_RX_ENABLE |
+ UARTn_CTRL_RX_INT_ENABLE |
+ UARTn_CTRL_RX_OVERRUN_INT_ENABLE);
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+}
+
+static void mps2_uart_enable_ms(struct uart_port *port)
+{
+}
+
+static void mps2_uart_break_ctl(struct uart_port *port, int ctl)
+{
+}
+
+static void mps2_uart_rx_chars(struct uart_port *port)
+{
+ struct tty_port *tport = &port->state->port;
+
+ while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_RX_FULL) {
+ u8 rxdata = mps2_uart_read8(port, UARTn_DATA);
+
+ port->icount.rx++;
+ tty_insert_flip_char(&port->state->port, rxdata, TTY_NORMAL);
+ };
+
+ spin_unlock(&port->lock);
+ tty_flip_buffer_push(tport);
+ spin_lock(&port->lock);
+}
+
+static irqreturn_t mps2_uart_rxirq(int irq, void *data)
+{
+
+ struct uart_port *port = data;
+ u8 irqflag = mps2_uart_read8(port, UARTn_INT);
+
+ if (unlikely(!(irqflag & UARTn_INT_RX)))
+ return IRQ_NONE;
+
+ spin_lock(&port->lock);
+
+ mps2_uart_write8(port, UARTn_INT_RX, UARTn_INT);
+ mps2_uart_rx_chars(port);
+
+ spin_unlock(&port->lock);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t mps2_uart_txirq(int irq, void *data)
+{
+ struct uart_port *port = data;
+ u8 irqflag = mps2_uart_read8(port, UARTn_INT);
+
+ if (unlikely(!(irqflag & UARTn_INT_TX)))
+ return IRQ_NONE;
+
+ mps2_uart_write8(port, UARTn_INT_TX, UARTn_INT);
+ mps2_uart_tx_chars(port);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t mps2_uart_oerrirq(int irq, void *data)
+{
+ irqreturn_t handled = IRQ_NONE;
+ struct uart_port *port = data;
+ u8 irqflag = mps2_uart_read8(port, UARTn_INT);
+
+ spin_lock(&port->lock);
+
+ if (irqflag & UARTn_INT_RX_OVERRUN) {
+ struct tty_port *tport = &port->state->port;
+
+ mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT);
+ tty_insert_flip_char(tport, 0, TTY_OVERRUN);
+ port->icount.overrun++;
+ handled = IRQ_HANDLED;
+ }
+
+ /* XXX: this shouldn't happen? */
+ if (irqflag & UARTn_INT_TX_OVERRUN) {
+ mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
+ handled = IRQ_HANDLED;
+ }
+
+ spin_unlock(&port->lock);
+
+ return handled;
+}
+
+static int mps2_uart_startup(struct uart_port *port)
+{
+ struct mps2_uart_port *mps_port = to_mps2_port(port);
+ u8 control = mps2_uart_read8(port, UARTn_CTRL);
+ int ret;
+
+ control &= ~(UARTn_CTRL_RX_ENABLE |
+ UARTn_CTRL_TX_ENABLE |
+ UARTn_CTRL_RX_INT_ENABLE |
+ UARTn_CTRL_TX_INT_ENABLE |
+ UARTn_CTRL_RX_OVERRUN_INT_ENABLE |
+ UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+
+ ret = request_irq(mps_port->rx_irq, mps2_uart_rxirq, 0,
+ MAKE_NAME(-rx), mps_port);
+ if (ret) {
+ pr_info("failed to register rxirq (%d)\n", ret);
+ goto err_no_rxirq;
+ }
+
+ ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
+ MAKE_NAME(-tx), mps_port);
+ if (ret) {
+ pr_info("failed to register txirq (%d)\n", ret);
+ goto err_no_txirq;
+ }
+
+ ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
+ MAKE_NAME(-overrun), mps_port);
+
+ if (ret)
+ pr_info("failed to register oerrirq (%d)\n", ret);
+ else {
+ control |= UARTn_CTRL_RX_ENABLE |
+ UARTn_CTRL_TX_ENABLE |
+ UARTn_CTRL_RX_INT_ENABLE |
+ UARTn_CTRL_TX_INT_ENABLE |
+ UARTn_CTRL_RX_OVERRUN_INT_ENABLE |
+ UARTn_CTRL_TX_OVERRUN_INT_ENABLE;
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+
+ return 0;
+ }
+
+ free_irq(mps_port->tx_irq, mps_port);
+err_no_txirq:
+ free_irq(mps_port->rx_irq, mps_port);
+err_no_rxirq:
+ return ret;
+}
+
+static void mps2_uart_shutdown(struct uart_port *port)
+{
+ struct mps2_uart_port *mps_port = to_mps2_port(port);
+ u8 control = mps2_uart_read8(port, UARTn_CTRL);
+
+ control &= ~(UARTn_CTRL_RX_ENABLE |
+ UARTn_CTRL_TX_ENABLE |
+ UARTn_CTRL_RX_INT_ENABLE |
+ UARTn_CTRL_TX_INT_ENABLE |
+ UARTn_CTRL_RX_OVERRUN_INT_ENABLE |
+ UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+ mps2_uart_write8(port, control, UARTn_CTRL);
+
+ free_irq(mps_port->rx_irq, mps_port);
+ free_irq(mps_port->tx_irq, mps_port);
+ free_irq(port->irq, mps_port);
+}
+
+static void mps2_uart_set_termios(struct uart_port *port,
+ struct ktermios *new, struct ktermios *old)
+{
+ unsigned long flags;
+ unsigned int baud, bauddiv;
+
+ new->c_cflag &= ~(CRTSCTS | CMSPAR);
+ new->c_cflag &= ~CSIZE;
+ new->c_cflag |= CS8;
+ new->c_cflag &= ~PARENB;
+ new->c_cflag &= ~CSTOPB;
+
+ baud = uart_get_baud_rate(port, new, old,
+ DIV_ROUND_CLOSEST(port->uartclk, UARTn_BAUDDIV_MASK),
+ DIV_ROUND_CLOSEST(port->uartclk, 16));
+
+ bauddiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ uart_update_timeout(port, new->c_cflag, baud);
+ mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *mps2_uart_type(struct uart_port *port)
+{
+ return (port->type == PORT_MPS2UART) ? DRIVER_NAME : NULL;
+}
+
+static void mps2_uart_release_port(struct uart_port *port)
+{
+}
+
+static int mps2_uart_request_port(struct uart_port *port)
+{
+ return 0;
+}
+
+static void mps2_uart_config_port(struct uart_port *port, int type)
+{
+ if (type & UART_CONFIG_TYPE && !mps2_uart_request_port(port))
+ port->type = PORT_MPS2UART;
+}
+
+static int mps2_uart_verify_port(struct uart_port *port, struct serial_struct *serinfo)
+{
+ return -EINVAL;
+}
+
+static const struct uart_ops mps2_uart_pops = {
+ .tx_empty = mps2_uart_tx_empty,
+ .set_mctrl = mps2_uart_set_mctrl,
+ .get_mctrl = mps2_uart_get_mctrl,
+ .stop_tx = mps2_uart_stop_tx,
+ .start_tx = mps2_uart_start_tx,
+ .stop_rx = mps2_uart_stop_rx,
+ .enable_ms = mps2_uart_enable_ms,
+ .break_ctl = mps2_uart_break_ctl,
+ .startup = mps2_uart_startup,
+ .shutdown = mps2_uart_shutdown,
+ .set_termios = mps2_uart_set_termios,
+ .type = mps2_uart_type,
+ .release_port = mps2_uart_release_port,
+ .request_port = mps2_uart_request_port,
+ .config_port = mps2_uart_config_port,
+ .verify_port = mps2_uart_verify_port,
+};
+
+static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
+
+#ifdef CONFIG_SERIAL_MPS2_UART_CONSOLE
+static void mps2_uart_console_putchar(struct uart_port *port, int ch)
+{
+ while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)
+ cpu_relax();
+
+ mps2_uart_write8(port, ch, UARTn_DATA);
+}
+
+static void mps2_uart_console_write(struct console *co, const char *s, unsigned int cnt)
+{
+ struct uart_port *port = &mps2_uart_ports[co->index].port;
+
+ uart_console_write(port, s, cnt, mps2_uart_console_putchar);
+}
+
+static int mps2_uart_console_setup(struct console *co, char *options)
+{
+ struct mps2_uart_port *mps_port;
+ int baud = 9600;
+ int bits = 8;
+ int parity = 'n';
+ int flow = 'n';
+
+ if (co->index < 0 || co->index >= MPS2_MAX_PORTS)
+ return -ENODEV;
+
+ mps_port = &mps2_uart_ports[co->index];
+
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+ return uart_set_options(&mps_port->port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver mps2_uart_driver;
+
+static struct console mps2_uart_console = {
+ .name = SERIAL_NAME,
+ .device = uart_console_device,
+ .write = mps2_uart_console_write,
+ .setup = mps2_uart_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+ .data = &mps2_uart_driver,
+};
+
+#define MPS2_SERIAL_CONSOLE (&mps2_uart_console)
+
+#else
+#define MPS2_SERIAL_CONSOLE NULL
+#endif
+
+static struct uart_driver mps2_uart_driver = {
+ .driver_name = DRIVER_NAME,
+ .dev_name = SERIAL_NAME,
+ .nr = MPS2_MAX_PORTS,
+ .cons = MPS2_SERIAL_CONSOLE,
+};
+
+static struct mps2_uart_port *mps2_of_get_port(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ int id;
+
+ if (!np)
+ return NULL;
+
+ id = of_alias_get_id(np, "serial");
+ if (id < 0)
+ id = 0;
+
+ if (WARN_ON(id >= MPS2_MAX_PORTS))
+ return NULL;
+
+ mps2_uart_ports[id].port.line = id;
+ return &mps2_uart_ports[id];
+}
+
+static int mps2_init_port(struct mps2_uart_port *mps_port,
+ struct platform_device *pdev)
+{
+ int ret = 0;
+ struct resource *res;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ mps_port->port.membase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(mps_port->port.membase))
+ return PTR_ERR(mps_port->port.membase);
+
+ mps_port->port.mapbase = res->start;
+ mps_port->port.mapsize = resource_size(res);
+
+ mps_port->rx_irq = platform_get_irq(pdev, 0);
+ mps_port->tx_irq = platform_get_irq(pdev, 1);
+ mps_port->port.irq = platform_get_irq(pdev, 2);
+
+ mps_port->port.iotype = UPIO_MEM;
+ mps_port->port.flags = UPF_BOOT_AUTOCONF;
+ mps_port->port.fifosize = 1;
+ mps_port->port.ops = &mps2_uart_pops;
+ mps_port->port.dev = &pdev->dev;
+
+ mps_port->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(mps_port->clk))
+ return PTR_ERR(mps_port->clk);
+
+ ret = clk_prepare_enable(mps_port->clk);
+ if (ret)
+ return ret;
+
+ mps_port->port.uartclk = clk_get_rate(mps_port->clk);
+ if (!mps_port->port.uartclk)
+ ret = -EINVAL;
+
+ clk_disable_unprepare(mps_port->clk);
+
+ return ret;
+}
+
+static int mps2_serial_probe(struct platform_device *pdev)
+{
+ struct mps2_uart_port *mps_port;
+ int ret;
+
+ mps_port = mps2_of_get_port(pdev);
+ if (!mps_port)
+ return -ENODEV;
+
+ ret = mps2_init_port(mps_port, pdev);
+ if (ret)
+ return ret;
+
+ ret = uart_add_one_port(&mps2_uart_driver, &mps_port->port);
+ if (ret)
+ return ret;
+
+ platform_set_drvdata(pdev, mps_port);
+
+ return 0;
+}
+
+static int mps2_serial_remove(struct platform_device *pdev)
+{
+ struct mps2_uart_port *mps_port = platform_get_drvdata(pdev);
+
+ uart_remove_one_port(&mps2_uart_driver, &mps_port->port);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id mps2_match[] = {
+ { .compatible = "arm,mps2-uart", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mps2_match);
+#endif
+
+static struct platform_driver mps2_serial_driver = {
+ .probe = mps2_serial_probe,
+ .remove = mps2_serial_remove,
+
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = of_match_ptr(mps2_match),
+ },
+};
+
+static int __init mps2_uart_init(void)
+{
+ int ret;
+
+ ret = uart_register_driver(&mps2_uart_driver);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&mps2_serial_driver);
+ if (ret)
+ uart_unregister_driver(&mps2_uart_driver);
+
+ pr_info("MPS2 UART driver initialized\n");
+
+ return ret;
+}
+module_init(mps2_uart_init);
+
+static void __exit mps2_uart_exit(void)
+{
+ platform_driver_unregister(&mps2_serial_driver);
+ uart_unregister_driver(&mps2_uart_driver);
+}
+module_exit(mps2_uart_exit);
+
+MODULE_AUTHOR("Vladimir Murzin <vladimir.murzin@arm.com>");
+MODULE_DESCRIPTION("MPS2 UART driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 93ba148..f097fe9 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -261,4 +261,7 @@
/* STM32 USART */
#define PORT_STM32 113

+/* MPS2 UART */
+#define PORT_MPS2UART 114
+
#endif /* _UAPILINUX_SERIAL_CORE_H */
--
1.7.9.5