On 01/03/2018 19:11, Andy Shevchenko wrote:
On Tue, 2018-02-27 at 00:40 +0800, John Garry wrote:
From: Zhichang Yuan <yuanzhich...@hisilicon.com>

In commit 41f8bba7f555 ("of/pci: Add pci_register_io_range() and
pci_pio_to_address()"), a new I/O space management was supported. With
that driver, the I/O ranges configured for PCI/PCIe hosts on some
architectures can be mapped to logical PIO, converted easily between
CPU address and the corresponding logicial PIO. Based on this, PCI
I/O devices can be accessed in a memory read/write way through the
unified in/out accessors.

But on some archs/platforms, there are bus hosts which access I/O
peripherals with host-local I/O port addresses rather than memory
addresses after memory-mapped.

To support those devices, a more generic I/O mapping method is
introduced
here. Through this patch, both the CPU addresses and the host-local
port
can be mapped into the logical PIO space with different logical/fake
PIOs.
After this, all the I/O accesses to either PCI MMIO devices or host-
local
I/O peripherals can be unified into the existing I/O accessors defined
in
asm-generic/io.h and be redirected to the right device-specific hooks
based on the input logical PIO.


A bit more small comments.



Hi Andy,

+#ifndef __LINUX_LOGIC_PIO_H
+#define __LINUX_LOGIC_PIO_H
+

+#ifdef __KERNEL__

Hmm... How the header in include/linux/ can be non-kernel?

I did doubt the legitimacy of this. I think it should be ok to remove.


+       list_for_each_entry_rcu(range, &io_range_list, list) {

+               if (range->flags == LOGIC_PIO_CPU_MMIO &&
+                               new_range->flags ==
LOGIC_PIO_CPU_MMIO) {

It's rather fancy indentation.

Right, I should align these.


+                       if (start >= range->hw_start + range->size ||
+                           end < range->hw_start)

Misses {}

Right, I will fix.


+                               allocated_mmio_size += range->size;
+                       else {
+                               ret = -EFAULT;
+                               goto end_register;
+                       }

+               if (allocated_mmio_size + new_range->size - 1 >
+                       MMIO_UPPER_LIMIT) {

Fancy indentation.

+                       if (allocated_mmio_size + SZ_64K - 1 >
+                       MMIO_UPPER_LIMIT) {

Ditto.

Will fix both


+               if (allocated_iio_size + new_range->size - 1 >
+                   IO_SPACE_LIMIT) {

While this is nothing wrong, like above I would consider to check how
long it is and consider putting on one line.

Fine. Some symbol names can be shortened to aid this.


+/**
+ * logic_pio_to_hwaddr - translate logical PIO to HW address
+ * @pio: logical PIO value
+ *
+ * Returns HW address if valid, -1 otherwise

It can't return -1 when the return type is unsigned.

+ *
+ * Translate the input logical pio to the corresponding hardware
address.
+ * The input pio should be unique in the whole logical PIO space.
+ */
+resource_size_t logic_pio_to_hwaddr(unsigned long pio)
+{
+       struct logic_pio_hwaddr *range;

+       resource_size_t hwaddr = (resource_size_t)-1;

Ditto.

ok, I should have changed this to ~0 also.


+       return hwaddr;
+}

+       list_for_each_entry_rcu(range, &io_range_list, list) {
+               if (range->flags != LOGIC_PIO_CPU_MMIO)
+                       continue;

+               if (addr >= range->hw_start &&
+                   addr < range->hw_start + range->size)

Perhaps you may copy'n'paste in_range() macro from fs/ext* files and use
in this module. At some point it would be good to make it generic.

OK, I should be able to copy. It would not be good to include fs/ufs/util.h, but a generic helper would be useful.


+                       return addr - range->hw_start +
+                               range->io_start;


+       }



Thanks very much,
John


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