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
23 static void __iomem *avr_addr;
24 static unsigned long avr_clock;
25
26 static struct work_struct wd_work;
27
wd_stop(struct work_struct * unused)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
avr_uart_configure(void)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
avr_uart_send(const char c)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
ls_uart_init(void)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
ls_uarts_init(void)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