device/pnp_device: rewrite pnp_get_ioresource
The rewrite simplifies the code and fixes the limit on the case of IO resources
with the length of 1 byte.
This patch is inspired by the comment of Nico Huber on
Ia99b785dcd9cf56fb236ad7ade54656851f88a5e
If the ones in the mask aren't a continuous block, now a warning message gets
printed.
Change-Id: I0089278f5adf65e8f084580bc5bc1eb2f77b87f7
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-on: https://review.coreboot.org/27654
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
diff --git a/src/device/pnp_device.c b/src/device/pnp_device.c
index 5600231..09a2748 100644
--- a/src/device/pnp_device.c
+++ b/src/device/pnp_device.c
@@ -7,6 +7,7 @@
* Copyright (C) 2005 Tyan
* (Written by Yinghai Lu <yhlu@tyan.com> for Tyan)
* Copyright (C) 2013 Nico Huber <nico.h@gmx.de>
+ * Copyright (C) 2018 Felix Held <felix-coreboot@felixheld.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -194,8 +195,10 @@
static void pnp_get_ioresource(struct device *dev, u8 index, u16 mask)
{
struct resource *resource;
- unsigned moving, gran, step;
+ unsigned int bit;
+ /* If none of the mask bits is set, the resource would occupy the whole
+ IO space leading to IO resource conflicts with the other devices */
if (!mask) {
printk(BIOS_ERR, "ERROR: device %s index %d has no mask.\n",
dev_path(dev), index);
@@ -203,43 +206,31 @@
}
resource = new_resource(dev, index);
-
- /* Initilize the resource. */
- resource->limit = 0xffff;
resource->flags |= IORESOURCE_IO;
- /* Get the resource size... */
+ /* Calculate IO region size which is determined by the first one from
+ the LSB of the mask. */
+ for (bit = 0; bit <= 15 && (mask & (1 << bit)) == 0; ++bit)
+ ;
- moving = mask;
- gran = 15;
- step = 1 << gran;
+ resource->gran = bit;
+ resource->align = bit;
+ resource->size = 1 << bit;
- /* Find the first bit that moves. */
- while ((moving & step) == 0) {
- gran--;
- step >>= 1;
- }
+ /* Calculate IO region address limit which is determined by the first
+ one from the MSB of the mask. */
+ for (bit = 15; bit != 0 && (mask & (1 << bit)) == 0; --bit)
+ ;
- /* Now find the first bit that does not move. */
- while ((moving & step) != 0) {
- gran--;
- step >>= 1;
- }
+ resource->limit = (1 << (bit + 1)) - 1;
- /*
- * Of the moving bits the last bit in the first group,
- * tells us the size of this resource.
- */
- if ((moving & step) == 0) {
- gran++;
- step <<= 1;
- }
-
- /* Set the resource size and alignment. */
- resource->gran = gran;
- resource->align = gran;
- resource->limit = mask | (step - 1);
- resource->size = 1 << gran;
+ /* The block of ones in the mask is expected to be continuous.
+ If there is any zero inbetween the block of ones, it is ignored
+ in the calculation of the resource size and limit. */
+ if (mask != (resource->limit ^ (resource->size - 1)))
+ printk(BIOS_WARNING,
+ "WARNING: mask of device %s index %d is wrong.\n",
+ dev_path(dev), index);
}
static void get_resources(struct device *dev, struct pnp_info *info)