isa.txt: standardize document format
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@ -1,5 +1,6 @@
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===========
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ISA Drivers
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ISA Drivers
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-----------
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===========
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The following text is adapted from the commit message of the initial
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The following text is adapted from the commit message of the initial
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commit of the ISA bus driver authored by Rene Herman.
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commit of the ISA bus driver authored by Rene Herman.
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@ -23,17 +24,17 @@ that all device creation has been made internal as well.
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The usage model this provides is nice, and has been acked from the ALSA
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The usage model this provides is nice, and has been acked from the ALSA
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side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_init's
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side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_init's
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now (for oldisa-only drivers) become:
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now (for oldisa-only drivers) become::
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static int __init alsa_card_foo_init(void)
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static int __init alsa_card_foo_init(void)
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{
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{
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return isa_register_driver(&snd_foo_isa_driver, SNDRV_CARDS);
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return isa_register_driver(&snd_foo_isa_driver, SNDRV_CARDS);
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}
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}
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static void __exit alsa_card_foo_exit(void)
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static void __exit alsa_card_foo_exit(void)
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{
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{
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isa_unregister_driver(&snd_foo_isa_driver);
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isa_unregister_driver(&snd_foo_isa_driver);
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}
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}
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Quite like the other bus models therefore. This removes a lot of
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Quite like the other bus models therefore. This removes a lot of
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duplicated init code from the ALSA ISA drivers.
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duplicated init code from the ALSA ISA drivers.
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@ -47,11 +48,11 @@ parameter, indicating how many devices to create and call our methods
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with.
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with.
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The platform_driver callbacks are called with a platform_device param;
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The platform_driver callbacks are called with a platform_device param;
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the isa_driver callbacks are being called with a "struct device *dev,
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the isa_driver callbacks are being called with a ``struct device *dev,
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unsigned int id" pair directly -- with the device creation completely
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unsigned int id`` pair directly -- with the device creation completely
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internal to the bus it's much cleaner to not leak isa_dev's by passing
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internal to the bus it's much cleaner to not leak isa_dev's by passing
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them in at all. The id is the only thing we ever want other then the
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them in at all. The id is the only thing we ever want other then the
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struct device * anyways, and it makes for nicer code in the callbacks as
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struct device anyways, and it makes for nicer code in the callbacks as
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well.
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well.
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With this additional .match() callback ISA drivers have all options. If
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With this additional .match() callback ISA drivers have all options. If
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@ -75,20 +76,20 @@ This exports only two functions; isa_{,un}register_driver().
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isa_register_driver() register's the struct device_driver, and then
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isa_register_driver() register's the struct device_driver, and then
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loops over the passed in ndev creating devices and registering them.
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loops over the passed in ndev creating devices and registering them.
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This causes the bus match method to be called for them, which is:
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This causes the bus match method to be called for them, which is::
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int isa_bus_match(struct device *dev, struct device_driver *driver)
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int isa_bus_match(struct device *dev, struct device_driver *driver)
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{
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{
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struct isa_driver *isa_driver = to_isa_driver(driver);
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struct isa_driver *isa_driver = to_isa_driver(driver);
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if (dev->platform_data == isa_driver) {
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if (dev->platform_data == isa_driver) {
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if (!isa_driver->match ||
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if (!isa_driver->match ||
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isa_driver->match(dev, to_isa_dev(dev)->id))
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isa_driver->match(dev, to_isa_dev(dev)->id))
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return 1;
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return 1;
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dev->platform_data = NULL;
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dev->platform_data = NULL;
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}
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}
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return 0;
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return 0;
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}
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}
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The first thing this does is check if this device is in fact one of this
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The first thing this does is check if this device is in fact one of this
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driver's devices by seeing if the device's platform_data pointer is set
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driver's devices by seeing if the device's platform_data pointer is set
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@ -102,7 +103,7 @@ well.
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Then, if the the driver did not provide a .match, it matches. If it did,
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Then, if the the driver did not provide a .match, it matches. If it did,
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the driver match() method is called to determine a match.
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the driver match() method is called to determine a match.
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If it did _not_ match, dev->platform_data is reset to indicate this to
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If it did **not** match, dev->platform_data is reset to indicate this to
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isa_register_driver which can then unregister the device again.
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isa_register_driver which can then unregister the device again.
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If during all this, there's any error, or no devices matched at all
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If during all this, there's any error, or no devices matched at all
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