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-rw-r--r--drivers/tty/serial/8250/8250_early.c221
1 files changed, 221 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
new file mode 100644
index 000000000..ccacbf0f1
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Early serial console for 8250/16550 devices
+ *
+ * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
+ * Bjorn Helgaas <bjorn.helgaas@hp.com>
+ *
+ * Based on the 8250.c serial driver, Copyright (C) 2001 Russell King,
+ * and on early_printk.c by Andi Kleen.
+ *
+ * This is for use before the serial driver has initialized, in
+ * particular, before the UARTs have been discovered and named.
+ * Instead of specifying the console device as, e.g., "ttyS0",
+ * we locate the device directly by its MMIO or I/O port address.
+ *
+ * The user can specify the device directly, e.g.,
+ * earlycon=uart8250,io,0x3f8,9600n8
+ * earlycon=uart8250,mmio,0xff5e0000,115200n8
+ * earlycon=uart8250,mmio32,0xff5e0000,115200n8
+ * or
+ * console=uart8250,io,0x3f8,9600n8
+ * console=uart8250,mmio,0xff5e0000,115200n8
+ * console=uart8250,mmio32,0xff5e0000,115200n8
+ */
+
+#include <linux/tty.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/serial_reg.h>
+#include <linux/serial.h>
+#include <linux/serial_8250.h>
+#include <asm/io.h>
+#include <asm/serial.h>
+
+static unsigned int serial8250_early_in(struct uart_port *port, int offset)
+{
+ int reg_offset = offset;
+ offset <<= port->regshift;
+
+ switch (port->iotype) {
+ case UPIO_MEM:
+ return readb(port->membase + offset);
+ case UPIO_MEM16:
+ return readw(port->membase + offset);
+ case UPIO_MEM32:
+ return readl(port->membase + offset);
+ case UPIO_MEM32BE:
+ return ioread32be(port->membase + offset);
+ case UPIO_PORT:
+ return inb(port->iobase + offset);
+ case UPIO_AU:
+ return port->serial_in(port, reg_offset);
+ default:
+ return 0;
+ }
+}
+
+static void serial8250_early_out(struct uart_port *port, int offset, int value)
+{
+ int reg_offset = offset;
+ offset <<= port->regshift;
+
+ switch (port->iotype) {
+ case UPIO_MEM:
+ writeb(value, port->membase + offset);
+ break;
+ case UPIO_MEM16:
+ writew(value, port->membase + offset);
+ break;
+ case UPIO_MEM32:
+ writel(value, port->membase + offset);
+ break;
+ case UPIO_MEM32BE:
+ iowrite32be(value, port->membase + offset);
+ break;
+ case UPIO_PORT:
+ outb(value, port->iobase + offset);
+ break;
+ case UPIO_AU:
+ port->serial_out(port, reg_offset, value);
+ break;
+ }
+}
+
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+static void serial_putc(struct uart_port *port, int c)
+{
+ unsigned int status;
+
+ serial8250_early_out(port, UART_TX, c);
+
+ for (;;) {
+ status = serial8250_early_in(port, UART_LSR);
+ if ((status & BOTH_EMPTY) == BOTH_EMPTY)
+ break;
+ cpu_relax();
+ }
+}
+
+static void early_serial8250_write(struct console *console,
+ const char *s, unsigned int count)
+{
+ struct earlycon_device *device = console->data;
+ struct uart_port *port = &device->port;
+
+ uart_console_write(port, s, count, serial_putc);
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+static int early_serial8250_read(struct console *console,
+ char *s, unsigned int count)
+{
+ struct earlycon_device *device = console->data;
+ struct uart_port *port = &device->port;
+ unsigned int status;
+ int num_read = 0;
+
+ while (num_read < count) {
+ status = serial8250_early_in(port, UART_LSR);
+ if (!(status & UART_LSR_DR))
+ break;
+ s[num_read++] = serial8250_early_in(port, UART_RX);
+ }
+
+ return num_read;
+}
+#else
+#define early_serial8250_read NULL
+#endif
+
+static void __init init_port(struct earlycon_device *device)
+{
+ struct uart_port *port = &device->port;
+ unsigned int divisor;
+ unsigned char c;
+ unsigned int ier;
+
+ serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */
+ ier = serial8250_early_in(port, UART_IER);
+ serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */
+ serial8250_early_out(port, UART_FCR, 0); /* no fifo */
+ serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */
+
+ if (port->uartclk) {
+ divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
+ c = serial8250_early_in(port, UART_LCR);
+ serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
+ serial8250_early_out(port, UART_DLL, divisor & 0xff);
+ serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
+ serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
+ }
+}
+
+int __init early_serial8250_setup(struct earlycon_device *device,
+ const char *options)
+{
+ if (!(device->port.membase || device->port.iobase))
+ return -ENODEV;
+
+ if (!device->baud) {
+ struct uart_port *port = &device->port;
+ unsigned int ier;
+
+ /* assume the device was initialized, only mask interrupts */
+ ier = serial8250_early_in(port, UART_IER);
+ serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
+ } else
+ init_port(device);
+
+ device->con->write = early_serial8250_write;
+ device->con->read = early_serial8250_read;
+ return 0;
+}
+EARLYCON_DECLARE(uart8250, early_serial8250_setup);
+EARLYCON_DECLARE(uart, early_serial8250_setup);
+OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
+OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
+OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
+OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
+
+#ifdef CONFIG_SERIAL_8250_OMAP
+
+static int __init early_omap8250_setup(struct earlycon_device *device,
+ const char *options)
+{
+ struct uart_port *port = &device->port;
+
+ if (!(device->port.membase || device->port.iobase))
+ return -ENODEV;
+
+ port->regshift = 2;
+ device->con->write = early_serial8250_write;
+ return 0;
+}
+
+OF_EARLYCON_DECLARE(omap8250, "ti,omap2-uart", early_omap8250_setup);
+OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
+OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);
+OF_EARLYCON_DECLARE(omap8250, "ti,am654-uart", early_omap8250_setup);
+
+#endif
+
+#ifdef CONFIG_SERIAL_8250_RT288X
+
+unsigned int au_serial_in(struct uart_port *p, int offset);
+void au_serial_out(struct uart_port *p, int offset, int value);
+
+static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
+{
+ dev->port.serial_in = au_serial_in;
+ dev->port.serial_out = au_serial_out;
+ dev->port.iotype = UPIO_AU;
+ dev->con->write = early_serial8250_write;
+ return 0;
+}
+OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
+
+#endif