hwmon: (it87) Add support for the IT8721F/IT8758E

Add support for the IT8721F/IT8758E. These new chips differ from the
older IT87xxF chips in the following ways:
* ADC LSB is 12 mV instead of 16 mV.
* PWM values are 8-bit instead of 7-bit.
There are other minor changes we don't have to care about in the
driver.

Another change is that we will handle internal voltage scaling in the
driver instead of delegating the work to user-space.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 19 insertions, 9 deletions

diff --git a/Documentation/hwmon/it87 b/Documentation/hwmon/it87
index 8d08bf0d38ed..38425f0f2645 100644
--- a/Documentation/hwmon/it87
+++ b/Documentation/hwmon/it87
@@ -22,6 +22,10 @@ Supported chips:
     Prefix: 'it8720'
     Addresses scanned: from Super I/O config space (8 I/O ports)
     Datasheet: Not publicly available
+  * IT8721F/IT8758E
+    Prefix: 'it8721'
+    Addresses scanned: from Super I/O config space (8 I/O ports)
+    Datasheet: Not publicly available
   * SiS950   [clone of IT8705F]
     Prefix: 'it87'
     Addresses scanned: from Super I/O config space (8 I/O ports)
@@ -67,7 +71,7 @@ Description
 -----------
 
 This driver implements support for the IT8705F, IT8712F, IT8716F,
-IT8718F, IT8720F, IT8726F and SiS950 chips.
+IT8718F, IT8720F, IT8721F, IT8726F, IT8758E and SiS950 chips.
 
 These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
 joysticks and other miscellaneous stuff. For hardware monitoring, they
@@ -86,14 +90,15 @@ the driver won't notice and report changes in the VID value. The two
 upper VID bits share their pins with voltage inputs (in5 and in6) so you
 can't have both on a given board.
 
-The IT8716F, IT8718F, IT8720F and later IT8712F revisions have support for
-2 additional fans. The additional fans are supported by the driver.
+The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
+have support for 2 additional fans. The additional fans are supported by the
+driver.
 
-The IT8716F, IT8718F and IT8720F, and late IT8712F and IT8705F also have
-optional 16-bit tachometer counters for fans 1 to 3. This is better (no more
-fan clock divider mess) but not compatible with the older chips and
-revisions. The 16-bit tachometer mode is enabled by the driver when one
-of the above chips is detected.
+The IT8716F, IT8718F, IT8720F and IT8721F/IT8758E, and late IT8712F and
+IT8705F also have optional 16-bit tachometer counters for fans 1 to 3. This
+is better (no more fan clock divider mess) but not compatible with the older
+chips and revisions. The 16-bit tachometer mode is enabled by the driver when
+one of the above chips is detected.
 
 The IT8726F is just bit enhanced IT8716F with additional hardware
 for AMD power sequencing. Therefore the chip will appear as IT8716F
@@ -115,7 +120,12 @@ alarm is triggered if the voltage has crossed a programmable minimum or
 maximum limit. Note that minimum in this case always means 'closest to
 zero'; this is important for negative voltage measurements. All voltage
 inputs can measure voltages between 0 and 4.08 volts, with a resolution of
-0.016 volt. The battery voltage in8 does not have limit registers.
+0.016 volt (except IT8721F/IT8758E: 0.012 volt.) The battery voltage in8 does
+not have limit registers.
+
+On the IT8721F/IT8758E, some voltage inputs are internal and scaled inside
+the chip (in7, in8 and optionally in3). The driver handles this transparently
+so user-space doesn't have to care.
 
 The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
 the voltage level your processor should work with. This is hardcoded by