Changeset 1093

Timestamp:

05/26/01 23:23:40 (12 years ago)

Author:

mds

Message:

Apply tristate patch from Jesus Arias <jesus@…>

which ensures i2c Bus is tristated correctly. It isn't clear from
the datasheet if the 586's GPIO pins are open drain or not,
but if they aren't, then the driver was driving the pins high
rather than letting them get pulled high as the spec requires.
This is corrected by toggling the direction rather than the
data register to control the bus.

Location:

lm-sensors/trunk

Files:

• CHANGES (modified) (1 diff)
• kernel/busses/i2c-via.c (modified) (3 diffs)

lm-sensors/trunk/CHANGES

@@ -41 +41 @@
   Module i2c-i810: Fixed i2c_i810_init() not found in patched kernel
   Module i2c-sis5595: Allow force_addr=0xaddr; enable if not enabled.
+  Module i2c-via: Ensure i2c bus is tristated correctly.
   Module lm78: Recognize chipid=0x20
   Module lm87: Fix in0, in1 (2.5V and Vccp1) calculations

lm-sensors/trunk/kernel/busses/i2c-via.c

@@ -64 +64 @@
 static u16 pm_io_base;
 
+/*
+   It does not appear from the datasheet that the GPIO pins are
+   open drain. So a we set a low value by setting the direction to
+   output and a high value by setting the direction to input and
+   relying on the required I2C pullup. The data value is initialized
+   to 0 in i2c_via_init() and never changed.
+*/
+
 static void bit_via_setscl(void *data, int state)
 {
-        outb(state ? inb(I2C_OUT) | I2C_SCL : inb(I2C_OUT) & ~I2C_SCL,
-             I2C_OUT);
+        outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL,
+             I2C_DIR);
 }
 
 static void bit_via_setsda(void *data, int state)
 {
-        outb(state ? inb(I2C_OUT) | I2C_SDA : inb(I2C_OUT) & ~I2C_SDA,
-             I2C_OUT);
+        outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA,
+             I2C_DIR);
 }
 
@@ -180 +188 @@
         } else {
                 request_region(I2C_DIR, IOSPACE, IOTEXT);
-                outb(inb(I2C_DIR) | I2C_SDA | I2C_SCL, I2C_DIR);
-                outb(inb(I2C_OUT) | I2C_SDA | I2C_SCL, I2C_OUT);
+                outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
+                outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);
         }
 
@@ -188 +196 @@
                 return 0;
         } else {
-                outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
                 release_region(I2C_DIR, IOSPACE);
                 printk