this patch set
01 - adds superio_locks -
drivers needing superio access register, and get a 'slot'with port-id
info and a mutex,
multiple drivers share the same 'slot', and coordinate access with its
mutex.
superio_find() - finds and reserves the slot, returned as ptr or
null
superio_release() - relinguishes the slot (ref-counted)
Once theyve got the reservation in struct superio * gate (as done in
patches 2,3,4)
they *may* use
superio_lock(gate)
superio_inb(gate, addr),
superio_outb(gate, addr, val)
or they can do it themselves with inb/outb, and gate->sioaddr, etc.
My objective was to be as
superio_find was chosen to fit the idiom used in hwmon/*.c
02 - use it in pc8736x_gpio
this driver keeps the slot for the lifetime of the module ( __init til
__exit )
03 - uses it in pc87360
this driver keeps the slot for only during __init, since it only needs to
read the ISA addresses of the Logical Devices in the chip.
04 - use it in rest of drivers/hwmon/*.c
this patch is compile-tested only, please review for sanity before you
try running them.
OPERATION
Here they are, working on my soekris box
- with #define DEBUG 1, and sysctl -w kernel.printk=8
simple sharing:
soekris:~# modprobe pc8736x_gpio
[ 201.308543] platform pc8736x_gpio.0: NatSemi pc8736x GPIO Driver
Initializing
[ 201.319118] got e9 want e1
[ 201.322297] no devid:e1 at port:2e
[ 201.325996] got e9 want e8
[ 201.328770] no devid:e8 at port:2e
[ 201.332375] got e9 want e4
[ 201.335259] no devid:e4 at port:2e
[ 201.338847] got e9 want e5
[ 201.341728] no devid:e5 at port:2e
[ 201.349112] allocating slot 0, addr 2e for device e9
[ 201.354345] found devid:e9 port:2e users:1
[ 201.371547] platform pc8736x_gpio.0: GPIO ioport 6600 reserved
soekris:~#
soekris:~# modprobe pc87360
[ 201.757736] got e9 want e1
[ 201.760694] no devid:e1 at port:2e
[ 201.764317] got e9 want e8
[ 201.767263] no devid:e8 at port:2e
[ 201.770899] got e9 want e4
[ 201.773669] no devid:e4 at port:2e
[ 201.777248] got e9 want e5
[ 201.780135] no devid:e5 at port:2e
[ 201.783731] sharing port:2e dev:e9 users:2
[ 201.788015] found devid:e9 port:2e users:2
[ 201.806848] pc87360: Device 0x09 not activated
[ 201.827262] pc87360 pc87360.26144: VLM conversion set to 1s period,
160us delay
soekris:~#
soekris:~# rmmod pc8736x_gpio
[ 206.934821] releasing last user of superio-port 2e
soekris:~# rmmod pc87360
I removed both, but the slot released after the 1st,
because the other module released it at end of init,
and is no longer holding the reservation
soekris:~# modprobe pc87360
[ 208.173676] got e9 want e1
[ 208.176483] no devid:e1 at port:2e
[ 208.180115] got e9 want e8
[ 208.183028] no devid:e8 at port:2e
[ 208.186625] got e9 want e4
[ 208.189515] no devid:e4 at port:2e
[ 208.192986] got e9 want e5
[ 208.195865] no devid:e5 at port:2e
[ 208.203700] allocating slot 0, addr 2e for device e9
[ 208.209125] found devid:e9 port:2e users:1
[ 208.214555] pc87360: Device 0x09 not activated
[ 208.219853] releasing last user of superio-port 2e
[ 208.252041] pc87360 pc87360.26144: VLM conversion set to 1s period,
160us delay
soekris:~#
again, can see init-only usage by driver, and last-release message.
soekris:~# modprobe pc8736x_gpio
[ 208.633842] platform pc8736x_gpio.0: NatSemi pc8736x GPIO Driver
Initializing
[ 208.643221] got e9 want e1
[ 208.646017] no devid:e1 at port:2e
[ 208.649634] got e9 want e8
[ 208.652566] no devid:e8 at port:2e
[ 208.656161] got e9 want e4
[ 208.659108] no devid:e4 at port:2e
[ 208.662584] got e9 want e5
[ 208.665457] no devid:e5 at port:2e
[ 208.680637] allocating slot 0, addr 2e for device e9
[ 208.685846] found devid:e9 port:2e users:1
[ 208.693420] platform pc8736x_gpio.0: GPIO ioport 6600 reserved
soekris:~#
can see here that we're the only holder of that reservation.
CAVEATS
- see 4
- Ive not thought much about the 16-bit device-id check
( I need hardware to sharpen this focus )
- superio_get() feels clumsy.
- superio_{enter,exit} are no-ops on my natsemi chip, so again the code
is {}
the prob is (of course) that every chip does it differently,
and superio_locks shouldnt care. Probably best to drop them
from superio-locks API, and expect drivers to do them themselves.
Callbacks are possible but pointless, but given that the driver author
must call enter & exit explicitly, they should just call their function
directly.
- no device knowledge (digression - for later)
its tempting to (create another module) to have a Logical-device table,
with strings to describe the LDs, etc. I dont want to dwell on it now,
except to avoid foreclosing design options by bad choices now (in
superio_locks).
struct sio_logical_device pc87366_units[] = {
{ 8, "Floppy Disk Controller (FDC)" },
{ 8, "Parallel Port (PP)" }, /* also 6 more at 0x400 */
{ 8, "Serial Port 2 with IR (SP2)" },
...
I suspect that a pointer field in struct superio could
carry whatever info a notional pc8736x_sio.ko would need,
but might pose some reclamation issues.
such a module should support interrogating the LD's config-regs,
extracting ISA addresses, etc, and could for example, add a bit
more detail for display in /proc/ioports, which currently shows:
6008-600d : NatSemi SCx200 High-Resolution Timer
6100-613f : 0000:00:12.0
6100-612b : NatSemi SCx200 GPIO
6200-623f : 0000:00:12.0
6300-63ff : 0000:00:12.1
6500-653f : 0000:00:12.5
6600-660f : pc8736x_gpio
6620-662f : pc87360
6640-664f : pc87360
6640-664f : pc87360
I suspect that the multiple pc87360 regions are for the LDs controlled
by hwmon/pc87360, since pc8736x_gpio also shows up (once).
It would be cool if they said which ldn, something like
6620-662f : pc87360.voltages
6640-664f : pc87360.temps
6640-664f : pc87360.dunno
<aside> Does it look 'right' to you ?
- superio_locks may be relevant elsewhere (ACPI ?) but I havent thought
about them
WHATS NEXT
- see if any drivers in patch 4 are sane/insane
probably break 4 into separate patches ..
- get the feedback --> fix the code
- submit formally
here ? LKML ? other subsystem MLs ?
thanks,
-jimc
