arch/mips/ath79/early_printk.c

   1 /*
   2  *  Atheros AR7XXX/AR9XXX SoC early printk support
   3  *
   4  *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
   5  *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify it
   8  *  under the terms of the GNU General Public License version 2 as published
   9  *  by the Free Software Foundation.
  10  */
  11
  12 #include <linux/io.h>
  13 #include <linux/errno.h>
  14 #include <linux/serial_reg.h>
  15 #include <asm/addrspace.h>
  16 #include <asm/setup.h>
  17
  18 #include <asm/mach-ath79/ath79.h>
  19 #include <asm/mach-ath79/ar71xx_regs.h>
  20 #include <asm/mach-ath79/ar933x_uart.h>
  21
  22 static void (*_prom_putchar)(char);
  23
  24 static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
  25 {
  26         u32 t;
  27
  28         do {
  29                 t = __raw_readl(reg);
  30                 if ((t & mask) == val)
  31                         break;
  32         } while (1);
  33 }
  34
  35 #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
  36
  37 static void prom_putchar_ar71xx(char ch)
  38 {
  39         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  40
  41         prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
  42         __raw_writel((unsigned char)ch, base + UART_TX * 4);
  43         prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
  44 }
  45
  46 static void prom_putchar_ar933x(char ch)
  47 {
  48         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
  49
  50         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  51                           AR933X_UART_DATA_TX_CSR);
  52         __raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
  53                      base + AR933X_UART_DATA_REG);
  54         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  55                           AR933X_UART_DATA_TX_CSR);
  56 }
  57
  58 static void prom_putchar_dummy(char ch)
  59 {
  60         /* nothing to do */
  61 }
  62
  63 static void prom_enable_uart(u32 id)
  64 {
  65         void __iomem *gpio_base;
  66         u32 uart_en;
  67         u32 t;
  68
  69         switch (id) {
  70         case REV_ID_MAJOR_AR71XX:
  71                 uart_en = AR71XX_GPIO_FUNC_UART_EN;
  72                 break;
  73
  74         case REV_ID_MAJOR_AR7240:
  75         case REV_ID_MAJOR_AR7241:
  76         case REV_ID_MAJOR_AR7242:
  77                 uart_en = AR724X_GPIO_FUNC_UART_EN;
  78                 break;
  79
  80         case REV_ID_MAJOR_AR913X:
  81                 uart_en = AR913X_GPIO_FUNC_UART_EN;
  82                 break;
  83
  84         case REV_ID_MAJOR_AR9330:
  85         case REV_ID_MAJOR_AR9331:
  86                 uart_en = AR933X_GPIO_FUNC_UART_EN;
  87                 break;
  88
  89         case REV_ID_MAJOR_AR9341:
  90         case REV_ID_MAJOR_AR9342:
  91         case REV_ID_MAJOR_AR9344:
  92                 /* TODO */
  93         default:
  94                 return;
  95         }
  96
  97         gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
  98         t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
  99         t |= uart_en;
 100         __raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
 101 }
 102
 103 static void prom_putchar_init(void)
 104 {
 105         void __iomem *base;
 106         u32 id;
 107
 108         base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
 109         id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
 110         id &= REV_ID_MAJOR_MASK;
 111
 112         switch (id) {
 113         case REV_ID_MAJOR_AR71XX:
 114         case REV_ID_MAJOR_AR7240:
 115         case REV_ID_MAJOR_AR7241:
 116         case REV_ID_MAJOR_AR7242:
 117         case REV_ID_MAJOR_AR913X:
 118         case REV_ID_MAJOR_AR9341:
 119         case REV_ID_MAJOR_AR9342:
 120         case REV_ID_MAJOR_AR9344:
 121         case REV_ID_MAJOR_QCA9533:
 122         case REV_ID_MAJOR_QCA9533_V2:
 123         case REV_ID_MAJOR_QCA9556:
 124         case REV_ID_MAJOR_QCA9558:
 125         case REV_ID_MAJOR_TP9343:
 126         case REV_ID_MAJOR_QCA956X:
 127                 _prom_putchar = prom_putchar_ar71xx;
 128                 break;
 129
 130         case REV_ID_MAJOR_AR9330:
 131         case REV_ID_MAJOR_AR9331:
 132                 _prom_putchar = prom_putchar_ar933x;
 133                 break;
 134
 135         default:
 136                 _prom_putchar = prom_putchar_dummy;
 137                 return;
 138         }
 139
 140         prom_enable_uart(id);
 141 }
 142
 143 void prom_putchar(char ch)
 144 {
 145         if (!_prom_putchar)
 146                 prom_putchar_init();
 147
 148         _prom_putchar(ch);
 149 }