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Message-Id: <34d77952d94c05b187e83e2de78b4de4533c5650.1460040201.git.vilhelm.gray@gmail.com>
Date: Thu, 7 Apr 2016 10:47:23 -0400
From: William Breathitt Gray <vilhelm.gray@...il.com>
To: gregkh@...uxfoundation.org, tglx@...utronix.de, jic23@...nel.org,
knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net, wim@...ana.be,
linux@...ck-us.net, linus.walleij@...aro.org, gnurou@...il.com
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
linux-watchdog@...r.kernel.org, linux-gpio@...r.kernel.org,
William Breathitt Gray <vilhelm.gray@...il.com>
Subject: [PATCH 02/10] isa: Implement the max_num_isa_dev macro
max_num_isa_dev is a macro to determine the maximum possible number of
ISA devices which may be registered in the I/O port address space given
the address extent of the ISA devices.
The highest base address possible for an ISA device is 0x3FF; this
results in 1024 possible base addresses. Dividing the number of possible
base addresses by the address extent taken by each device results in the
maximum number of devices on a system.
Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>
---
include/linux/isa.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/include/linux/isa.h b/include/linux/isa.h
index d410259..bc0a7c0 100644
--- a/include/linux/isa.h
+++ b/include/linux/isa.h
@@ -57,4 +57,15 @@ static void __exit __isa_driver##_exit(void) \
} \
module_exit(__isa_driver##_exit);
+/**
+ * max_num_isa_dev() - Maximum possible number registered of an ISA device
+ * @__ida_dev_ext: ISA device address extent
+ *
+ * The highest base address possible for an ISA device is 0x3FF; this results in
+ * 1024 possible base addresses. Dividing the number of possible base addresses
+ * by the address extent taken by each device results in the maximum number of
+ * devices on a system.
+ */
+#define max_num_isa_dev(__isa_dev_ext) (1024 / __isa_dev_ext)
+
#endif /* __LINUX_ISA_H */
--
2.7.3
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