ls_uart.c

  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
 24static void __iomem *avr_addr;
 25static unsigned long avr_clock;
 26
 27static struct work_struct wd_work;
 28
 29static 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
 59void 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
 82void 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
 93static 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
115static 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
147machine_late_initcall(linkstation, ls_uarts_init);