--- /dev/null
+/*
+ * 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 (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 (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");
Code Review / kvmfornfv.git / blobdiff