patch-2.1.80 linux/arch/arm/kernel/iic.c

• Lines: 161
• Date: Tue Jan 20 16:39:41 1998
• Orig file: v2.1.79/linux/arch/arm/kernel/iic.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.79/linux/arch/arm/kernel/iic.c linux/arch/arm/kernel/iic.c
@@ -0,0 +1,160 @@
+/*
+ * linux/arch/arm/kernel/iic.c
+ *
+ * Copyright (C) 1995, 1996 Russell King
+ *
+ * IIC is used to get the current time from the CMOS rtc.
+ */
+
+#include <asm/system.h>
+#include <asm/delay.h>
+#include <asm/io.h>
+#include <asm/hardware.h>
+
+/*
+ * if delay loop has been calibrated then us that,
+ * else use IOC timer 1.
+ */
+static void iic_delay (void)
+{
+	extern unsigned long loops_per_sec;
+	if (loops_per_sec != (1 << 12)) {
+		udelay(10);
+		return;
+	} else {
+		unsigned long flags;
+		save_flags_cli(flags);
+
+		outb(254,  IOC_T1LTCHL);
+		outb(255,  IOC_T1LTCHH);
+		outb(0,    IOC_T1GO);
+		outb(1<<6, IOC_IRQCLRA);			/* clear T1 irq */
+		outb(4,    IOC_T1LTCHL);
+		outb(0,    IOC_T1LTCHH);
+		outb(0,    IOC_T1GO);
+		while ((inb(IOC_IRQSTATA) & (1<<6)) == 0);
+		restore_flags(flags);
+	}
+}
+
+static inline void iic_start (void)
+{
+	unsigned char out;
+
+	out = inb(IOC_CONTROL) | 0xc2;
+
+	outb(out, IOC_CONTROL);
+	iic_delay();
+
+	outb(out ^ 1, IOC_CONTROL);
+	iic_delay();
+}
+
+static inline void iic_stop (void)
+{
+	unsigned char out;
+
+	out = inb(IOC_CONTROL) | 0xc3;
+
+	iic_delay();
+	outb(out ^ 1, IOC_CONTROL);
+
+	iic_delay();
+	outb(out, IOC_CONTROL);
+}
+
+static int iic_sendbyte (unsigned char b)
+{
+	unsigned char out, in;
+	int i;
+
+	out = (inb(IOC_CONTROL) & 0xfc) | 0xc0;
+
+	outb(out, IOC_CONTROL);
+	for (i = 7; i >= 0; i--) {
+		unsigned char c;
+		c = out | ((b & (1 << i)) ? 1 : 0);
+
+		outb(c, IOC_CONTROL);
+		iic_delay();
+
+		outb(c | 2, IOC_CONTROL);
+		iic_delay();
+
+		outb(c, IOC_CONTROL);
+	}
+	outb(out | 1, IOC_CONTROL);
+	iic_delay();
+
+	outb(out | 3, IOC_CONTROL);
+	iic_delay();
+
+	in = inb(IOC_CONTROL) & 1;
+
+	outb(out | 1, IOC_CONTROL);
+	iic_delay();
+
+	outb(out, IOC_CONTROL);
+	iic_delay();
+
+	if(in) {
+		printk("No acknowledge from RTC\n");
+		return 1;
+	} else
+		return 0;
+}
+
+static unsigned char iic_recvbyte (void)
+{
+	unsigned char out, in;
+	int i;
+
+	out = (inb(IOC_CONTROL) & 0xfc) | 0xc0;
+
+	outb(out, IOC_CONTROL);
+	in = 0;
+	for (i = 7; i >= 0; i--) {
+		outb(out | 1, IOC_CONTROL);
+		iic_delay();
+		outb(out | 3, IOC_CONTROL);
+		iic_delay();
+		in = (in << 1) | (inb(IOC_CONTROL) & 1);
+		outb(out | 1, IOC_CONTROL);
+		iic_delay();
+	}
+	outb(out, IOC_CONTROL);
+	iic_delay();
+	outb(out | 2, IOC_CONTROL);
+	iic_delay();
+
+	return in;
+}
+
+void iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len)
+{
+	iic_start();
+
+	if (iic_sendbyte(addr & 0xfe))
+		goto error;
+
+	if (iic_sendbyte(loc))
+		goto error;
+
+	if (addr & 1) {
+		int i;
+
+		for (i = 0; i < len; i++)
+			if (iic_sendbyte (buf[i]))
+				break;
+	} else {
+		int i;
+
+		iic_stop();
+		iic_start();
+		iic_sendbyte(addr|1);
+		for (i = 0; i < len; i++)
+			buf[i] = iic_recvbyte ();
+	}
+error:
+	iic_stop();
+}