serial: Add Broadcom BCM63xx UART implementation

Broadcom BCM63xx DSL SoCs utilize a proprietary UART which requires a custom implementation to be done. This code is an adaptation of Linux's arch/mips/bcm63xx/early_printk.c file. Signed-off-by: Florian Fainelli <[email protected]>
zonque · Jul 29, 2015 · 93fd173 · 93fd173
1 parent c3da82f
commit 93fd173
Showing 1 changed file with 30 additions and 0 deletions.
diff --git a/serial-bcm63xx.c b/serial-bcm63xx.c
@@ -0,0 +1,30 @@
+#include "types.h"
+#include "register.h"
+#include "serial.h"
+
+#define UART_IR_REG			0x10
+#define UART_IR_STAT(x)			(1 << (x))
+#define UART_IR_TXEMPTY			5
+#define UART_FIFO_REG			0x14
+
+/* Implementation ripped from arch/mips/bcm63xx/early_printk.c. Thanks to
+ * Maxime Bizon for the original code.
+ */
+static void wait_xfered(void)
+{
+	unsigned int val;
+
+	/* wait for any previous char to be transmitted */
+	do {
+		val = readl(UART_BASE + UART_IR_REG);
+		if (val & UART_IR_STAT(UART_IR_TXEMPTY))
+			break;
+	} while (1);
+}
+
+void __putch(char c)
+{
+	wait_xfered();
+	writel(c, UART_BASE + UART_FIFO_REG);
+	wait_xfered();
+}