Im trying to update scx200_gpio to properly use the 2.6 api
(and thus learn it)
attached patch does following:
- register chrdev-region for 32 devices, (or alloc-chrdev-region)
- allocate array of 32 cdevs,
- initialize each cdev in scx200_gpio_init()
with gpio_fops, and major, minors
What follows, is a stream-of-conciousness, discover, a bit of fumbling ..
its a monologue in search of a dialogue ..
One thing missing wrt current best practice is
the lack of dev_dbg(), etc to control debug messages.
I cant figure out how to get a dev I can use.
1st printk()s Id like to lose are in fops write-handler
static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
unsigned m = iminor(file->f_dentry->d_inode);
...
case 'O':
printk(KERN_INFO NAME ": GPIO%d output
enabled\n", m);
scx200_gpio_configure(m, ~1, 1);
break;
Oooh, I think the light just went on...
If I set up file->private_data with the right info, then the dev is
obtainable.
right now, (in patch 5) I do
(retrieval, and initialization, in write-handler, and open-handler
respectively)
chr-scx200-gpio-vtable-calls:+ struct gpio_access_methods *amp =
file->private_data;
chr-scx200-gpio-vtable-calls:+ file->private_data = &scx200_access;
access-methods has .owner, with THIS_MODULE.
add a struct device *,
or something that contains one, like:
platform_device, miscdevice, probably many others.
so, wheres my device ?
dont I automatically get one, perhaps under the covers ?
why isnt/arent there THIS_DRIVER, THIS_PLATFORM, THIS_BUS constructs ?
THIS_MODULE storage is magically populated
( during what? compilation, module-loading, init ?)
couldnt the others be also (if later).
I also found this:
**Subject: Driver model ISA bus**
http://marc.theaimsgroup.com/?l=linux-kernel&m=114678055902797&w=2
It looks interesting - anything that simplifies stuff is -
but alas - theres no empty-isa-driver.c for me to start from.
.. any comments ?
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