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-rw-r--r--sys/dev/i2c/i2c_scan.c147
1 files changed, 116 insertions, 31 deletions
diff --git a/sys/dev/i2c/i2c_scan.c b/sys/dev/i2c/i2c_scan.c
index 48464ca9bf0..099b5fa8960 100644
--- a/sys/dev/i2c/i2c_scan.c
+++ b/sys/dev/i2c/i2c_scan.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: i2c_scan.c,v 1.87 2006/07/15 19:39:56 kettenis Exp $ */
+/* $OpenBSD: i2c_scan.c,v 1.88 2006/08/18 17:35:19 deraadt Exp $ */
/*
* Copyright (c) 2005 Theo de Raadt <deraadt@openbsd.org>
@@ -143,23 +143,34 @@ iicprobe(u_int8_t cmd)
#define LM77TMASK 0xfff8 /* 13 bits in temperature registers */
/*
- * The LM75/LM77 family are very hard to detect. Thus, we check for
- * all other possible chips first. These chips do not have an ID
- * register. They do have a few quirks though:
- * register 0x06 and 0x07 return whatever value was read before
- * the LM75 lacks registers 0x04 and 0x05, so those act as above
- * the chip registers loop every 8 registers
+ * The LM75/LM75A/LM77 family are very hard to detect. Thus, we check
+ * for all other possible chips first. These chips do not have an
+ * ID register. They do have a few quirks though:
+ * - on the LM75 and LM77, registers 0x06 and 0x07 return whatever
+ * value was read before
+ * - the LM75 lacks registers 0x04 and 0x05, so those act as above
+ * - the LM75A returns 0xffff for registers 0x04, 0x05, 0x06 and 0x07
+ * - the chip registers loop every 8 registers
* The downside is that we must read almost every register to guess
- * if this is an LM75 or LM77.
+ * if this is an LM75, LM75A or LM77.
*/
char *
lm75probe(void)
{
u_int16_t temp, thyst, tos, tlow, thigh, mask = LM75TMASK;
u_int8_t conf;
- int ret = 75, i;
+ int i, echocount, ffffcount, score;
+ int echoreg67, echoreg45, ffffreg67, ffffreg45;
temp = iicprobew(LM75TEMP);
+
+ /*
+ * Sometimes the other probes can upset the chip, if we get 0xffff
+ * the first time, try it once more.
+ */
+ if (temp == 0xffff)
+ temp = iicprobew(LM75TEMP);
+
conf = iicprobenc(LM75CONF);
thyst = iicprobew(LM75Thyst);
tos = iicprobew(LM75Tos);
@@ -185,24 +196,54 @@ lm75probe(void)
/*
* LM77/LM75 registers 6, 7
* echo whatever was read just before them from reg 0, 1, or 2
+ *
+ * LM75A doesn't appear to do this, but does appear to reliably
+ * return 0xffff
*/
- for (i = 6; i <= 7; i++) {
+ for (i = 6, echocount = 2, ffffcount = 0; i <= 7; i++) {
if ((iicprobew(LM75TEMP) & mask) != (iicprobew(i) & mask) ||
(iicprobew(LM75Thyst) & mask) != (iicprobew(i) & mask) ||
(iicprobew(LM75Tos) & mask) != (iicprobew(i) & mask))
- return (NULL);
+ echocount--;
+ if (iicprobew(i) == 0xffff)
+ ffffcount++;
}
+ /* Make sure either both registers echo, or neither does */
+ if (echocount == 1 || ffffcount == 1)
+ return (NULL);
+
+ echoreg67 = (echocount == 0) ? 0 : 1;
+ ffffreg67 = (ffffcount == 0) ? 0 : 1;
+
/*
* LM75 has no registers 4 or 5, and they will act as echos too
- * If we find that 4 and 5 are not echos, then we may have a LM77
+ *
+ * LM75A doesn't appear to do this either, but does appear to
+ * reliably return 0xffff
*/
- for (i = 4; i <= 5; i++) {
- if ((iicprobew(LM75TEMP) & mask) == (iicprobew(i) & mask) &&
- (iicprobew(LM75Thyst) & mask) == (iicprobew(i) & mask) &&
- (iicprobew(LM75Tos) & mask) == (iicprobew(i) & mask))
- continue;
- ret = 77;
+ for (i = 4, echocount = 2, ffffcount = 0; i <= 5; i++) {
+ if ((iicprobew(LM75TEMP) & mask) != (iicprobew(i) & mask) ||
+ (iicprobew(LM75Thyst) & mask) != (iicprobew(i) & mask) ||
+ (iicprobew(LM75Tos) & mask) != (iicprobew(i) & mask))
+ echocount--;
+ if (iicprobew(i) == 0xffff)
+ ffffcount++;
+ }
+
+ /* Make sure either both registers echo, or neither does */
+ if (echocount == 1 || ffffcount == 1)
+ return (NULL);
+
+ echoreg45 = (echocount == 0) ? 0 : 1;
+ ffffreg45 = (ffffcount == 0) ? 0 : 1;
+
+ /*
+ * If we find that 4 and 5 are not echos, and don't return 0xffff
+ * then based on whether the echo test of registers 6 and 7
+ * succeeded or not, we may have an LM77
+ */
+ if (echoreg45 == 0 && ffffreg45 == 0 && echoreg67 == 1) {
mask = LM77TMASK;
/* mask size changed, must re-read for the next checks */
@@ -210,35 +251,79 @@ lm75probe(void)
tos = iicprobew(LM75Tos) & mask;
tlow = iicprobew(LM77Tlow) & mask;
thigh = iicprobew(LM77Thigh) & mask;
- break;
}
- /* a real LM75/LM77 repeats it's registers.... */
+ /* a real LM75/LM75A/LM77 repeats it's registers.... */
for (i = 0x08; i <= 0xf8; i += 8) {
if (conf != iicprobenc(LM75CONF + i) ||
thyst != (iicprobew(LM75Thyst + i) & mask) ||
tos != (iicprobew(LM75Tos + i) & mask))
return (NULL);
- tos = iicprobew(LM75Tos) & mask;
- if (tos != (iicprobew(0x06 + i) & mask) ||
- tos != (iicprobew(0x07 + i) & mask))
- return (NULL);
- if (ret == 75) {
+
+ /*
+ * Check that the repeated registers 0x06 and 0x07 still
+ * either echo or return 0xffff
+ */
+ if (echoreg67 == 1) {
+ tos = iicprobew(LM75Tos) & mask;
+ if (tos != (iicprobew(0x06 + i) & mask) ||
+ tos != (iicprobew(0x07 + i) & mask))
+ return (NULL);
+ } else if (ffffreg67 == 1)
+ if (iicprobew(0x06 + i) != 0xffff ||
+ iicprobew(0x07 + i) != 0xffff)
+ return (NULL);
+
+ /*
+ * Check that the repeated registers 0x04 and 0x05 still
+ * either echo or return 0xffff. If they do neither, and
+ * registers 0x06 and 0x07 echo, then we will be probing
+ * for an LM77, so make sure those still repeat
+ */
+ if (echoreg45 == 1) {
tos = iicprobew(LM75Tos) & mask;
if (tos != (iicprobew(LM77Tlow + i) & mask) ||
tos != (iicprobew(LM77Thigh + i) & mask))
return (NULL);
- } else {
+ } else if (ffffreg45 == 1) {
+ if (iicprobew(LM77Tlow + i) != 0xffff ||
+ iicprobew(LM77Thigh + i) != 0xffff)
+ return (NULL);
+ } else if (echoreg67 == 1)
if (tlow != (iicprobew(LM77Tlow + i) & mask) ||
thigh != (iicprobew(LM77Thigh + i) & mask))
return (NULL);
- }
}
- /* We hope */
- if (ret == 75)
+ /*
+ * Given that we now know how the first eight registers behave and
+ * that this behaviour is consistently repeated, we can now use
+ * the following table:
+ *
+ * echoreg67 | echoreg45 | ffffreg67 | ffffreg45 | chip
+ * ----------+-----------+-----------+-----------+------
+ * 1 | 1 | 0 | 0 | LM75
+ * 1 | 0 | 0 | 0 | LM77
+ * 0 | 0 | 1 | 1 | LM75A
+ */
+
+ /* Convert the various flags into a single score */
+ score = (echoreg67 << 3) + (echoreg45 << 2) + (ffffreg67 << 1) +
+ ffffreg45;
+
+ switch (score) {
+ case 12:
return ("lm75");
- return ("lm77");
+ case 8:
+ return ("lm77");
+ case 3:
+ return ("lm75a");
+ default:
+#if defined(I2C_DEBUG) || defined(I2C_VERBOSE)
+ printf("lm75probe: unknown chip, scored %d\n", score);
+#endif /* defined(I2C_DEBUG) || defined(I2C_VERBOSE) */
+ return (NULL);
+ }
}
char *
@@ -677,7 +762,7 @@ iic_probe(struct device *self, struct i2cbus_attach_args *iba, u_int8_t addr)
iicprobe(0x16) == 0x41 && ((iicprobe(0x17) & 0xf0) == 0x40)) {
name = "adm1026";
} else if (name == NULL &&
- (addr & 0x7c) == 0x48) { /* addr 0b1001xxx */
+ (addr & 0x78) == 0x48) { /* addr 0b1001xxx */
name = lm75probe();
}
#if 0
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