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Diffstat (limited to 'arch/nios2/kernel/early_printk.c')
-rw-r--r--arch/nios2/kernel/early_printk.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/arch/nios2/kernel/early_printk.c b/arch/nios2/kernel/early_printk.c
new file mode 100644
index 000000000000..c08e4c1486fc
--- /dev/null
+++ b/arch/nios2/kernel/early_printk.c
@@ -0,0 +1,118 @@
+/*
+ * Early printk for Nios2.
+ *
+ * Copyright (C) 2015, Altera Corporation
+ * Copyright (C) 2010, Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009, Wind River Systems Inc
+ * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+
+#include <asm/prom.h>
+
+static unsigned long base_addr;
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
+
+#define ALTERA_JTAGUART_DATA_REG 0
+#define ALTERA_JTAGUART_CONTROL_REG 4
+#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000
+#define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400
+
+#define JUART_GET_CR() \
+ __builtin_ldwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG))
+#define JUART_SET_CR(v) \
+ __builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG), v)
+#define JUART_SET_TX(v) \
+ __builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_DATA_REG), v)
+
+static void early_console_write(struct console *con, const char *s, unsigned n)
+{
+ unsigned long status;
+
+ while (n-- && *s) {
+ while (((status = JUART_GET_CR())
+ & ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+ if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0)
+ return; /* no connection activity */
+#endif
+ }
+ JUART_SET_TX(*s);
+ s++;
+ }
+}
+
+#elif defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
+
+#define ALTERA_UART_TXDATA_REG 4
+#define ALTERA_UART_STATUS_REG 8
+#define ALTERA_UART_STATUS_TRDY 0x0040
+
+#define UART_GET_SR() \
+ __builtin_ldwio((void *)(base_addr + ALTERA_UART_STATUS_REG))
+#define UART_SET_TX(v) \
+ __builtin_stwio((void *)(base_addr + ALTERA_UART_TXDATA_REG), v)
+
+static void early_console_putc(char c)
+{
+ while (!(UART_GET_SR() & ALTERA_UART_STATUS_TRDY))
+ ;
+
+ UART_SET_TX(c);
+}
+
+static void early_console_write(struct console *con, const char *s, unsigned n)
+{
+ while (n-- && *s) {
+ early_console_putc(*s);
+ if (*s == '\n')
+ early_console_putc('\r');
+ s++;
+ }
+}
+
+#else
+# error Neither SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE \
+selected
+#endif
+
+static struct console early_console_prom = {
+ .name = "early",
+ .write = early_console_write,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .index = -1
+};
+
+void __init setup_early_printk(void)
+{
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) || \
+ defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
+ base_addr = of_early_console();
+#else
+ base_addr = 0;
+#endif
+
+ if (!base_addr)
+ return;
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+ /* Clear activity bit so BYPASS doesn't stall if we've used JTAG for
+ * downloading the kernel. This might cause early data to be lost even
+ * if the JTAG terminal is running.
+ */
+ JUART_SET_CR(JUART_GET_CR() | ALTERA_JTAGUART_CONTROL_AC_MSK);
+#endif
+
+ early_console = &early_console_prom;
+ register_console(early_console);
+ pr_info("early_console initialized at 0x%08lx\n", base_addr);
+}