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
17#include <asm/mach-ath79/ath79.h>
18#include <asm/mach-ath79/ar71xx_regs.h>
19#include <asm/mach-ath79/ar933x_uart.h>
20
21static void (*_prom_putchar) (unsigned char);
22
23static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
24{
25	u32 t;
26
27	do {
28		t = __raw_readl(reg);
29		if ((t & mask) == val)
30			break;
31	} while (1);
32}
33
34#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
35
36static void prom_putchar_ar71xx(unsigned char ch)
37{
38	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
39
40	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
41	__raw_writel(ch, base + UART_TX * 4);
42	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
43}
44
45static void prom_putchar_ar933x(unsigned char ch)
46{
47	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
48
49	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
50			  AR933X_UART_DATA_TX_CSR);
51	__raw_writel(AR933X_UART_DATA_TX_CSR | ch, base + AR933X_UART_DATA_REG);
52	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
53			  AR933X_UART_DATA_TX_CSR);
54}
55
56static void prom_putchar_dummy(unsigned char ch)
57{
58	/* nothing to do */
59}
60
61static void prom_putchar_init(void)
62{
63	void __iomem *base;
64	u32 id;
65
66	base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
67	id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
68	id &= REV_ID_MAJOR_MASK;
69
70	switch (id) {
71	case REV_ID_MAJOR_AR71XX:
72	case REV_ID_MAJOR_AR7240:
73	case REV_ID_MAJOR_AR7241:
74	case REV_ID_MAJOR_AR7242:
75	case REV_ID_MAJOR_AR913X:
76	case REV_ID_MAJOR_AR9341:
77	case REV_ID_MAJOR_AR9342:
78	case REV_ID_MAJOR_AR9344:
79	case REV_ID_MAJOR_QCA9556:
80	case REV_ID_MAJOR_QCA9558:
81		_prom_putchar = prom_putchar_ar71xx;
82		break;
83
84	case REV_ID_MAJOR_AR9330:
85	case REV_ID_MAJOR_AR9331:
86		_prom_putchar = prom_putchar_ar933x;
87		break;
88
89	default:
90		_prom_putchar = prom_putchar_dummy;
91		break;
92	}
93}
94
95void prom_putchar(unsigned char ch)
96{
97	if (!_prom_putchar)
98		prom_putchar_init();
99
100	_prom_putchar(ch);
101}
102