patch-2.4.22 linux-2.4.22/arch/cris/drivers/i2c.c

• Lines: 151
• Date: 2003-08-25 04:44:39.000000000 -0700
• Orig file: linux-2.4.21/arch/cris/drivers/i2c.c
• Orig date: 2003-06-13 07:51:29.000000000 -0700

diff -urN linux-2.4.21/arch/cris/drivers/i2c.c linux-2.4.22/arch/cris/drivers/i2c.c
@@ -11,7 +11,26 @@
 *! Jan 14 2000  Johan Adolfsson    Fixed PB shadow register stuff - 
 *!                                 don't use PB_I2C if DS1302 uses same bits,
 *!                                 use PB.
+*| June 23 2003 Pieter Grimmerink  Added 'i2c_sendnack'. i2c_readreg now
+*|                                 generates nack on last received byte, 
+*|                                 instead of ack.
+*|                                 i2c_getack changed data level while clock
+*|                                 was high, causing DS75 to see  a stop condition
+*|
 *! $Log: i2c.c,v $
+*! Revision 1.12  2003/06/23 14:43:47  oskarp
+*! * i2c_sendnack is added.
+*!   - i2c_readreg now generates nack on last received byte, instead of ack.
+*!     i2c_getack changed data level while clock was high, causing DS75 to
+*!     see a stop condition.
+*!
+*! Revision 1.11  2003/05/23 09:37:23  oskarp
+*! * Made i2c_init() visible.
+*!   - e.g. pcf856.c uses i2c_init().
+*!
+*! Revision 1.10  2003/04/01 14:12:06  starvik
+*! Added loglevel for lots of printks
+*!
 *! Revision 1.9  2002/10/31 15:32:26  starvik
 *! Update Port B register and shadow even when running with hardware support
 *!   to avoid glitches when reading bits
@@ -53,7 +72,7 @@
 *! (C) Copyright 1999-2002 Axis Communications AB, LUND, SWEDEN
 *!
 *!***************************************************************************/
-/* $Id: i2c.c,v 1.9 2002/10/31 15:32:26 starvik Exp $ */
+/* $Id: i2c.c,v 1.12 2003/06/23 14:43:47 oskarp Exp $ */
 /****************** INCLUDE FILES SECTION ***********************************/
 
 #include <linux/module.h>
@@ -133,7 +152,7 @@
 
 #define i2c_getbit() (((*R_PORT_PB_READ & (1 << SDABIT))) >> SDABIT)
 
-#else
+#else /* !CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C */
 /* enable or disable the i2c interface */
 
 #define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
@@ -163,7 +182,8 @@
 /* read a bit from the i2c interface */
 
 #define i2c_getbit() (*R_PORT_PB_READ & 0x1)
-#endif
+
+#endif /* CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C */
 
 /* use the kernels delay routine */
 
@@ -299,6 +319,12 @@
 	}
 	i2c_clk(I2C_CLOCK_HIGH);
 	i2c_delay(CLOCK_HIGH_TIME);
+	
+	/*
+	 * we leave the clock low, getbyte is usually followed
+	 * by sendack/nack, they assume the clock to be low
+	 */
+	i2c_clk(I2C_CLOCK_LOW);
 	return aBitByte;
 }
 
@@ -360,6 +386,13 @@
 		i2c_delay(CLOCK_HIGH_TIME/2);
 	}
 
+   /*
+    * our clock is high now, make sure data is low
+    * before we enable our output. If we keep data high
+    * and enable output, we would generate a stop condition.
+    */
+   i2c_data(I2C_DATA_LOW);
+   
 	/*
 	 * end clock pulse
 	 */
@@ -417,6 +450,37 @@
 
 /*#---------------------------------------------------------------------------
 *#
+*# FUNCTION NAME: i2c_sendnack
+*#
+*# DESCRIPTION  : Sends NACK on received data
+*#
+*#--------------------------------------------------------------------------*/
+void
+i2c_sendnack(void)
+{
+	/*
+	 * enable output
+	 */
+	i2c_delay(CLOCK_LOW_TIME);
+	i2c_dir_out();
+	/*
+	 * set data high
+	 */
+	i2c_data(I2C_DATA_HIGH);
+	/*
+	 * generate clock pulse
+	 */
+	i2c_delay(CLOCK_HIGH_TIME/6);
+	i2c_clk(I2C_CLOCK_HIGH);
+	i2c_delay(CLOCK_HIGH_TIME);
+	i2c_clk(I2C_CLOCK_LOW);
+	i2c_delay(CLOCK_LOW_TIME);
+	
+	i2c_dir_in();
+}
+
+/*#---------------------------------------------------------------------------
+*#
 *# FUNCTION NAME: i2c_writereg
 *#
 *# DESCRIPTION  : Writes a value to an I2C device
@@ -546,9 +610,10 @@
 		 */
 		b = i2c_inbyte();
 		/*
-		 * send Ack
+		 * last received byte needs to be nacked
+		 * instead of acked
 		 */
-		i2c_sendack();
+		i2c_sendnack();
 		/*
 		 * end sequence
 		 */
@@ -623,7 +688,7 @@
 	release:  i2c_release,
 };
 
-static int __init
+int __init
 i2c_init(void)
 {
 	int res;
@@ -653,7 +718,7 @@
 		return res;
 	}
 
-	printk("I2C driver v2.2, (c) 1999-2001 Axis Communications AB\n");
+	printk(KERN_INFO "I2C driver v2.2, (c) 1999-2001 Axis Communications AB\n");
 	
 	return 0;
 }