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 <linux/of_address.h>
19 #include <asm/io.h>
20 #include <asm/termbits.h>
21 
22 #include "mpc10x.h"
23 
24 static void __iomem *avr_addr;
25 static unsigned long avr_clock;
26 
27 static struct work_struct wd_work;
28 
29 static void wd_stop(struct work_struct *unused)
30 {
31 	const char string[] = "AAAAFFFFJJJJ>>>>VVVV>>>>ZZZZVVVVKKKK";
32 	int i = 0, rescue = 8;
33 	int len = strlen(string);
34 
35 	while (rescue--) {
36 		int j;
37 		char lsr = in_8(avr_addr + UART_LSR);
38 
39 		if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) {
40 			for (j = 0; j < 16 && i < len; j++, i++)
41 				out_8(avr_addr + UART_TX, string[i]);
42 			if (i == len) {
43 				/* Read "OK" back: 4ms for the last "KKKK"
44 				   plus a couple bytes back */
45 				msleep(7);
46 				printk("linkstation: disarming the AVR watchdog: ");
47 				while (in_8(avr_addr + UART_LSR) & UART_LSR_DR)
48 					printk("%c", in_8(avr_addr + UART_RX));
49 				break;
50 			}
51 		}
52 		msleep(17);
53 	}
54 	printk("\n");
55 }
56 
57 #define AVR_QUOT(clock) ((clock) + 8 * 9600) / (16 * 9600)
58 
59 void avr_uart_configure(void)
60 {
61 	unsigned char cval = UART_LCR_WLEN8;
62 	unsigned int quot = AVR_QUOT(avr_clock);
63 
64 	if (!avr_addr || !avr_clock)
65 		return;
66 
67 	out_8(avr_addr + UART_LCR, cval);			/* initialise UART */
68 	out_8(avr_addr + UART_MCR, 0);
69 	out_8(avr_addr + UART_IER, 0);
70 
71 	cval |= UART_LCR_STOP | UART_LCR_PARITY | UART_LCR_EPAR;
72 
73 	out_8(avr_addr + UART_LCR, cval);			/* Set character format */
74 
75 	out_8(avr_addr + UART_LCR, cval | UART_LCR_DLAB);	/* set DLAB */
76 	out_8(avr_addr + UART_DLL, quot & 0xff);		/* LS of divisor */
77 	out_8(avr_addr + UART_DLM, quot >> 8);			/* MS of divisor */
78 	out_8(avr_addr + UART_LCR, cval);			/* reset DLAB */
79 	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);	/* enable FIFO */
80 }
81 
82 void avr_uart_send(const char c)
83 {
84 	if (!avr_addr || !avr_clock)
85 		return;
86 
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 	out_8(avr_addr + UART_TX, c);
91 }
92 
93 static void __init ls_uart_init(void)
94 {
95 	local_irq_disable();
96 
97 #ifndef CONFIG_SERIAL_8250
98 	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);	/* enable FIFO */
99 	out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO |
100 	      UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);	/* clear FIFOs */
101 	out_8(avr_addr + UART_FCR, 0);
102 	out_8(avr_addr + UART_IER, 0);
103 
104 	/* Clear up interrupts */
105 	(void) in_8(avr_addr + UART_LSR);
106 	(void) in_8(avr_addr + UART_RX);
107 	(void) in_8(avr_addr + UART_IIR);
108 	(void) in_8(avr_addr + UART_MSR);
109 #endif
110 	avr_uart_configure();
111 
112 	local_irq_enable();
113 }
114 
115 static int __init ls_uarts_init(void)
116 {
117 	struct device_node *avr;
118 	struct resource res;
119 	int len, ret;
120 
121 	avr = of_find_node_by_path("/soc10x/serial@80004500");
122 	if (!avr)
123 		return -EINVAL;
124 
125 	avr_clock = *(u32*)of_get_property(avr, "clock-frequency", &len);
126 	if (!avr_clock)
127 		return -EINVAL;
128 
129 	ret = of_address_to_resource(avr, 0, &res);
130 	if (ret)
131 		return ret;
132 
133 	of_node_put(avr);
134 
135 	avr_addr = ioremap(res.start, 32);
136 	if (!avr_addr)
137 		return -EFAULT;
138 
139 	ls_uart_init();
140 
141 	INIT_WORK(&wd_work, wd_stop);
142 	schedule_work(&wd_work);
143 
144 	return 0;
145 }
146 
147 machine_late_initcall(linkstation, ls_uarts_init);
148