arch/mips/ath79/early_printk.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Atheros AR7XXX/AR9XXX SoC early printk support
   4  *
   5  *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
   6  *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   7  */
   8
   9 #include <linux/io.h>
  10 #include <linux/errno.h>
  11 #include <linux/serial.h>
  12 #include <linux/serial_reg.h>
  13 #include <asm/addrspace.h>
  14 #include <asm/setup.h>
  15
  16 #include <asm/mach-ath79/ath79.h>
  17 #include <asm/mach-ath79/ar71xx_regs.h>
  18 #include <asm/mach-ath79/ar933x_uart.h>
  19
  20 static void (*_prom_putchar)(char);
  21
  22 static inline void prom_putchar_wait(void __iomem *reg, u32 val)
  23 {
  24         u32 t;
  25
  26         do {
  27                 t = __raw_readl(reg);
  28                 if ((t & val) == val)
  29                         break;
  30         } while (1);
  31 }
  32
  33 static void prom_putchar_ar71xx(char ch)
  34 {
  35         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  36
  37         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
  38         __raw_writel((unsigned char)ch, base + UART_TX * 4);
  39         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
  40 }
  41
  42 static void prom_putchar_ar933x(char ch)
  43 {
  44         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
  45
  46         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
  47         __raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
  48                      base + AR933X_UART_DATA_REG);
  49         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
  50 }
  51
  52 static void prom_putchar_dummy(char ch)
  53 {
  54         /* nothing to do */
  55 }
  56
  57 static void prom_enable_uart(u32 id)
  58 {
  59         void __iomem *gpio_base;
  60         u32 uart_en;
  61         u32 t;
  62
  63         switch (id) {
  64         case REV_ID_MAJOR_AR71XX:
  65                 uart_en = AR71XX_GPIO_FUNC_UART_EN;
  66                 break;
  67
  68         case REV_ID_MAJOR_AR7240:
  69         case REV_ID_MAJOR_AR7241:
  70         case REV_ID_MAJOR_AR7242:
  71                 uart_en = AR724X_GPIO_FUNC_UART_EN;
  72                 break;
  73
  74         case REV_ID_MAJOR_AR913X:
  75                 uart_en = AR913X_GPIO_FUNC_UART_EN;
  76                 break;
  77
  78         case REV_ID_MAJOR_AR9330:
  79         case REV_ID_MAJOR_AR9331:
  80                 uart_en = AR933X_GPIO_FUNC_UART_EN;
  81                 break;
  82
  83         case REV_ID_MAJOR_AR9341:
  84         case REV_ID_MAJOR_AR9342:
  85         case REV_ID_MAJOR_AR9344:
  86                 /* TODO */
  87         default:
  88                 return;
  89         }
  90
  91         gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
  92         t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
  93         t |= uart_en;
  94         __raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
  95 }
  96
  97 static void prom_putchar_init(void)
  98 {
  99         void __iomem *base;
 100         u32 id;
 101
 102         base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
 103         id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
 104         id &= REV_ID_MAJOR_MASK;
 105
 106         switch (id) {
 107         case REV_ID_MAJOR_AR71XX:
 108         case REV_ID_MAJOR_AR7240:
 109         case REV_ID_MAJOR_AR7241:
 110         case REV_ID_MAJOR_AR7242:
 111         case REV_ID_MAJOR_AR913X:
 112         case REV_ID_MAJOR_AR9341:
 113         case REV_ID_MAJOR_AR9342:
 114         case REV_ID_MAJOR_AR9344:
 115         case REV_ID_MAJOR_QCA9533:
 116         case REV_ID_MAJOR_QCA9533_V2:
 117         case REV_ID_MAJOR_QCA9556:
 118         case REV_ID_MAJOR_QCA9558:
 119         case REV_ID_MAJOR_TP9343:
 120         case REV_ID_MAJOR_QCA956X:
 121         case REV_ID_MAJOR_QCN550X:
 122                 _prom_putchar = prom_putchar_ar71xx;
 123                 break;
 124
 125         case REV_ID_MAJOR_AR9330:
 126         case REV_ID_MAJOR_AR9331:
 127                 _prom_putchar = prom_putchar_ar933x;
 128                 break;
 129
 130         default:
 131                 _prom_putchar = prom_putchar_dummy;
 132                 return;
 133         }
 134
 135         prom_enable_uart(id);
 136 }
 137
 138 void prom_putchar(char ch)
 139 {
 140         if (!_prom_putchar)
 141                 prom_putchar_init();
 142
 143         _prom_putchar(ch);
 144 }