From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- Documentation/driver-api/zorro.rst | 104 +++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 Documentation/driver-api/zorro.rst (limited to 'Documentation/driver-api/zorro.rst') diff --git a/Documentation/driver-api/zorro.rst b/Documentation/driver-api/zorro.rst new file mode 100644 index 0000000000..664072b017 --- /dev/null +++ b/Documentation/driver-api/zorro.rst @@ -0,0 +1,104 @@ +======================================== +Writing Device Drivers for Zorro Devices +======================================== + +:Author: Written by Geert Uytterhoeven +:Last revised: September 5, 2003 + + +Introduction +------------ + +The Zorro bus is the bus used in the Amiga family of computers. Thanks to +AutoConfig(tm), it's 100% Plug-and-Play. + +There are two types of Zorro buses, Zorro II and Zorro III: + + - The Zorro II address space is 24-bit and lies within the first 16 MB of the + Amiga's address map. + + - Zorro III is a 32-bit extension of Zorro II, which is backwards compatible + with Zorro II. The Zorro III address space lies outside the first 16 MB. + + +Probing for Zorro Devices +------------------------- + +Zorro devices are found by calling ``zorro_find_device()``, which returns a +pointer to the ``next`` Zorro device with the specified Zorro ID. A probe loop +for the board with Zorro ID ``ZORRO_PROD_xxx`` looks like:: + + struct zorro_dev *z = NULL; + + while ((z = zorro_find_device(ZORRO_PROD_xxx, z))) { + if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE, + "My explanation")) + ... + } + +``ZORRO_WILDCARD`` acts as a wildcard and finds any Zorro device. If your driver +supports different types of boards, you can use a construct like:: + + struct zorro_dev *z = NULL; + + while ((z = zorro_find_device(ZORRO_WILDCARD, z))) { + if (z->id != ZORRO_PROD_xxx1 && z->id != ZORRO_PROD_xxx2 && ...) + continue; + if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE, + "My explanation")) + ... + } + + +Zorro Resources +--------------- + +Before you can access a Zorro device's registers, you have to make sure it's +not yet in use. This is done using the I/O memory space resource management +functions:: + + request_mem_region() + release_mem_region() + +Shortcuts to claim the whole device's address space are provided as well:: + + zorro_request_device + zorro_release_device + + +Accessing the Zorro Address Space +--------------------------------- + +The address regions in the Zorro device resources are Zorro bus address +regions. Due to the identity bus-physical address mapping on the Zorro bus, +they are CPU physical addresses as well. + +The treatment of these regions depends on the type of Zorro space: + + - Zorro II address space is always mapped and does not have to be mapped + explicitly using z_ioremap(). + + Conversion from bus/physical Zorro II addresses to kernel virtual addresses + and vice versa is done using:: + + virt_addr = ZTWO_VADDR(bus_addr); + bus_addr = ZTWO_PADDR(virt_addr); + + - Zorro III address space must be mapped explicitly using z_ioremap() first + before it can be accessed:: + + virt_addr = z_ioremap(bus_addr, size); + ... + z_iounmap(virt_addr); + + +References +---------- + +#. linux/include/linux/zorro.h +#. linux/include/uapi/linux/zorro.h +#. linux/include/uapi/linux/zorro_ids.h +#. linux/arch/m68k/include/asm/zorro.h +#. linux/drivers/zorro +#. /proc/bus/zorro + -- cgit v1.2.3