1 files changed, 146 insertions, 0 deletions
diff --git a/arch/mips/ath79/early_printk.c b/arch/mips/ath79/early_printk.c
new file mode 100644
index 000000000..782732cd1
--- /dev/null
+++ b/arch/mips/ath79/early_printk.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Atheros AR7XXX/AR9XXX SoC early printk support
+ *
+ *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ */
+
+#include <linux/io.h>
+#include <linux/errno.h>
+#include <linux/serial_reg.h>
+#include <asm/addrspace.h>
+#include <asm/setup.h>
+
+#include <asm/mach-ath79/ath79.h>
+#include <asm/mach-ath79/ar71xx_regs.h>
+#include <asm/mach-ath79/ar933x_uart.h>
+
+static void (*_prom_putchar)(char);
+
+static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
+{
+	u32 t;
+
+	do {
+		t = __raw_readl(reg);
+		if ((t & mask) == val)
+			break;
+	} while (1);
+}
+
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+static void prom_putchar_ar71xx(char ch)
+{
+	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
+
+	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
+	__raw_writel((unsigned char)ch, base + UART_TX * 4);
+	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
+}
+
+static void prom_putchar_ar933x(char ch)
+{
+	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
+
+	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
+			  AR933X_UART_DATA_TX_CSR);
+	__raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
+		     base + AR933X_UART_DATA_REG);
+	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
+			  AR933X_UART_DATA_TX_CSR);
+}
+
+static void prom_putchar_dummy(char ch)
+{
+	/* nothing to do */
+}
+
+static void prom_enable_uart(u32 id)
+{
+	void __iomem *gpio_base;
+	u32 uart_en;
+	u32 t;
+
+	switch (id) {
+	case REV_ID_MAJOR_AR71XX:
+		uart_en = AR71XX_GPIO_FUNC_UART_EN;
+		break;
+
+	case REV_ID_MAJOR_AR7240:
+	case REV_ID_MAJOR_AR7241:
+	case REV_ID_MAJOR_AR7242:
+		uart_en = AR724X_GPIO_FUNC_UART_EN;
+		break;
+
+	case REV_ID_MAJOR_AR913X:
+		uart_en = AR913X_GPIO_FUNC_UART_EN;
+		break;
+
+	case REV_ID_MAJOR_AR9330:
+	case REV_ID_MAJOR_AR9331:
+		uart_en = AR933X_GPIO_FUNC_UART_EN;
+		break;
+
+	case REV_ID_MAJOR_AR9341:
+	case REV_ID_MAJOR_AR9342:
+	case REV_ID_MAJOR_AR9344:
+		/* TODO */
+	default:
+		return;
+	}
+
+	gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
+	t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
+	t |= uart_en;
+	__raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
+}
+
+static void prom_putchar_init(void)
+{
+	void __iomem *base;
+	u32 id;
+
+	base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
+	id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
+	id &= REV_ID_MAJOR_MASK;
+
+	switch (id) {
+	case REV_ID_MAJOR_AR71XX:
+	case REV_ID_MAJOR_AR7240:
+	case REV_ID_MAJOR_AR7241:
+	case REV_ID_MAJOR_AR7242:
+	case REV_ID_MAJOR_AR913X:
+	case REV_ID_MAJOR_AR9341:
+	case REV_ID_MAJOR_AR9342:
+	case REV_ID_MAJOR_AR9344:
+	case REV_ID_MAJOR_QCA9533:
+	case REV_ID_MAJOR_QCA9533_V2:
+	case REV_ID_MAJOR_QCA9556:
+	case REV_ID_MAJOR_QCA9558:
+	case REV_ID_MAJOR_TP9343:
+	case REV_ID_MAJOR_QCA956X:
+		_prom_putchar = prom_putchar_ar71xx;
+		break;
+
+	case REV_ID_MAJOR_AR9330:
+	case REV_ID_MAJOR_AR9331:
+		_prom_putchar = prom_putchar_ar933x;
+		break;
+
+	default:
+		_prom_putchar = prom_putchar_dummy;
+		return;
+	}
+
+	prom_enable_uart(id);
+}
+
+void prom_putchar(char ch)
+{
+	if (!_prom_putchar)
+		prom_putchar_init();
+
+	_prom_putchar(ch);
+}