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 <linux/of.h>
18 #include <asm/io.h>
19 #include <asm/termbits.h>
20 
21 #include "mpc10x.h"
22 
23 static void __iomem *avr_addr;
24 static unsigned long avr_clock;
25 
26 static struct work_struct wd_work;
27 
28 static 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 
58 void 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 
81 void 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 
92 static 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 
114 static 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 
142 machine_late_initcall(linkstation, ls_uarts_init);
143