1/*
2 * AVR power-management chip interface for the Buffalo Linkstation /
3 * Kurobox Platform.
4 *
5 * Author: 2006 (c) G. Liakhovetski
6 *	 g.liakhovetski@gmx.de
7 *
8 * This file is licensed under the terms of the GNU General Public License
9 * version 2.  This program is licensed "as is" without any warranty of
10 * any kind, whether express or implied.
11 */
12#include <linux/workqueue.h>
13#include <linux/string.h>
14#include <linux/delay.h>
15#include <linux/serial_reg.h>
16#include <linux/serial_8250.h>
17#include <asm/io.h>
18#include <asm/prom.h>
19#include <asm/termbits.h>
20
21#include "mpc10x.h"
22
23static void __iomem *avr_addr;
24static unsigned long avr_clock;
25
26static struct work_struct wd_work;
27
28static void wd_stop(struct work_struct *unused)
29{
30	const char string[] = "AAAAFFFFJJJJ>>>>VVVV>>>>ZZZZVVVVKKKK";
31	int i = 0, rescue = 8;
32	int len = strlen(string);
33
34	while (rescue--) {
35		int j;
36		char lsr = in_8(avr_addr + UART_LSR);
37
38		if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) {
39			for (j = 0; j < 16 && i < len; j++, i++)
40				out_8(avr_addr + UART_TX, string[i]);
41			if (i == len) {
42				/* Read "OK" back: 4ms for the last "KKKK"
43				   plus a couple bytes back */
44				msleep(7);
45				printk("linkstation: disarming the AVR watchdog: ");
46				while (in_8(avr_addr + UART_LSR) & UART_LSR_DR)
47					printk("%c", in_8(avr_addr + UART_RX));
48				break;
49			}
50		}
51		msleep(17);
52	}
53	printk("\n");
54}
55
56#define AVR_QUOT(clock) ((clock) + 8 * 9600) / (16 * 9600)
57
58void avr_uart_configure(void)
59{
60	unsigned char cval = UART_LCR_WLEN8;
61	unsigned int quot = AVR_QUOT(avr_clock);
62
63	if (!avr_addr || !avr_clock)
64		return;
65
66	out_8(avr_addr + UART_LCR, cval);			/* initialise UART */
67	out_8(avr_addr + UART_MCR, 0);
68	out_8(avr_addr + UART_IER, 0);
69
70	cval |= UART_LCR_STOP | UART_LCR_PARITY | UART_LCR_EPAR;
71
72	out_8(avr_addr + UART_LCR, cval);			/* Set character format */
73
74	out_8(avr_addr + UART_LCR, cval | UART_LCR_DLAB);	/* set DLAB */
75	out_8(avr_addr + UART_DLL, quot & 0xff);		/* LS of divisor */
76	out_8(avr_addr + UART_DLM, quot >> 8);			/* MS of divisor */
77	out_8(avr_addr + UART_LCR, cval);			/* reset DLAB */
78	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);	/* enable FIFO */
79}
80
81void avr_uart_send(const char c)
82{
83	if (!avr_addr || !avr_clock)
84		return;
85
86	out_8(avr_addr + UART_TX, c);
87	out_8(avr_addr + UART_TX, c);
88	out_8(avr_addr + UART_TX, c);
89	out_8(avr_addr + UART_TX, c);
90}
91
92static void __init ls_uart_init(void)
93{
94	local_irq_disable();
95
96#ifndef CONFIG_SERIAL_8250
97	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);	/* enable FIFO */
98	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO |
99	      UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);	/* clear FIFOs */
100	out_8(avr_addr + UART_FCR, 0);
101	out_8(avr_addr + UART_IER, 0);
102
103	/* Clear up interrupts */
104	(void) in_8(avr_addr + UART_LSR);
105	(void) in_8(avr_addr + UART_RX);
106	(void) in_8(avr_addr + UART_IIR);
107	(void) in_8(avr_addr + UART_MSR);
108#endif
109	avr_uart_configure();
110
111	local_irq_enable();
112}
113
114static int __init ls_uarts_init(void)
115{
116	struct device_node *avr;
117	phys_addr_t phys_addr;
118	int len;
119
120	avr = of_find_node_by_path("/soc10x/serial@80004500");
121	if (!avr)
122		return -EINVAL;
123
124	avr_clock = *(u32*)of_get_property(avr, "clock-frequency", &len);
125	phys_addr = ((u32*)of_get_property(avr, "reg", &len))[0];
126
127	if (!avr_clock || !phys_addr)
128		return -EINVAL;
129
130	avr_addr = ioremap(phys_addr, 32);
131	if (!avr_addr)
132		return -EFAULT;
133
134	ls_uart_init();
135
136	INIT_WORK(&wd_work, wd_stop);
137	schedule_work(&wd_work);
138
139	return 0;
140}
141
142machine_late_initcall(linkstation, ls_uarts_init);
143