mips/ath79/early_printk.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  Atheros AR7XXX/AR9XXX SoC early printk support
0004  *
0005  *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
0006  *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
0007  */
0008
0009 #include <linux/io.h>
0010 #include <linux/errno.h>
0011 #include <linux/serial.h>
0012 #include <linux/serial_reg.h>
0013 #include <asm/addrspace.h>
0014 #include <asm/setup.h>
0015
0016 #include <asm/mach-ath79/ath79.h>
0017 #include <asm/mach-ath79/ar71xx_regs.h>
0018 #include <asm/mach-ath79/ar933x_uart.h>
0019
0020 static void (*_prom_putchar)(char);
0021
0022 static inline void prom_putchar_wait(void __iomem *reg, u32 val)
0023 {
0024     u32 t;
0025
0026     do {
0027         t = __raw_readl(reg);
0028         if ((t & val) == val)
0029             break;
0030     } while (1);
0031 }
0032
0033 static void prom_putchar_ar71xx(char ch)
0034 {
0035     void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
0036
0037     prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
0038     __raw_writel((unsigned char)ch, base + UART_TX * 4);
0039     prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
0040 }
0041
0042 static void prom_putchar_ar933x(char ch)
0043 {
0044     void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
0045
0046     prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
0047     __raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
0048              base + AR933X_UART_DATA_REG);
0049     prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
0050 }
0051
0052 static void prom_putchar_dummy(char ch)
0053 {
0054     /* nothing to do */
0055 }
0056
0057 static void prom_enable_uart(u32 id)
0058 {
0059     void __iomem *gpio_base;
0060     u32 uart_en;
0061     u32 t;
0062
0063     switch (id) {
0064     case REV_ID_MAJOR_AR71XX:
0065         uart_en = AR71XX_GPIO_FUNC_UART_EN;
0066         break;
0067
0068     case REV_ID_MAJOR_AR7240:
0069     case REV_ID_MAJOR_AR7241:
0070     case REV_ID_MAJOR_AR7242:
0071         uart_en = AR724X_GPIO_FUNC_UART_EN;
0072         break;
0073
0074     case REV_ID_MAJOR_AR913X:
0075         uart_en = AR913X_GPIO_FUNC_UART_EN;
0076         break;
0077
0078     case REV_ID_MAJOR_AR9330:
0079     case REV_ID_MAJOR_AR9331:
0080         uart_en = AR933X_GPIO_FUNC_UART_EN;
0081         break;
0082
0083     case REV_ID_MAJOR_AR9341:
0084     case REV_ID_MAJOR_AR9342:
0085     case REV_ID_MAJOR_AR9344:
0086         /* TODO */
0087     default:
0088         return;
0089     }
0090
0091     gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
0092     t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
0093     t |= uart_en;
0094     __raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
0095 }
0096
0097 static void prom_putchar_init(void)
0098 {
0099     void __iomem *base;
0100     u32 id;
0101
0102     base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
0103     id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
0104     id &= REV_ID_MAJOR_MASK;
0105
0106     switch (id) {
0107     case REV_ID_MAJOR_AR71XX:
0108     case REV_ID_MAJOR_AR7240:
0109     case REV_ID_MAJOR_AR7241:
0110     case REV_ID_MAJOR_AR7242:
0111     case REV_ID_MAJOR_AR913X:
0112     case REV_ID_MAJOR_AR9341:
0113     case REV_ID_MAJOR_AR9342:
0114     case REV_ID_MAJOR_AR9344:
0115     case REV_ID_MAJOR_QCA9533:
0116     case REV_ID_MAJOR_QCA9533_V2:
0117     case REV_ID_MAJOR_QCA9556:
0118     case REV_ID_MAJOR_QCA9558:
0119     case REV_ID_MAJOR_TP9343:
0120     case REV_ID_MAJOR_QCA956X:
0121     case REV_ID_MAJOR_QCN550X:
0122         _prom_putchar = prom_putchar_ar71xx;
0123         break;
0124
0125     case REV_ID_MAJOR_AR9330:
0126     case REV_ID_MAJOR_AR9331:
0127         _prom_putchar = prom_putchar_ar933x;
0128         break;
0129
0130     default:
0131         _prom_putchar = prom_putchar_dummy;
0132         return;
0133     }
0134
0135     prom_enable_uart(id);
0136 }
0137
0138 void prom_putchar(char ch)
0139 {
0140     if (!_prom_putchar)
0141         prom_putchar_init();
0142
0143     _prom_putchar(ch);
0144 }