There are three different ways of retrieving the I/O-memory ranges
for AST devices: either from PCI BAR 1, from PCI BAR 2 or from PCI
BAR 1 by 'guessing'.
Make the respective code more readable by making each case self-
contained. Also add error checking against the length of the PCI
BARs.
Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
drivers/gpu/drm/ast/ast_main.c | 40 +++++++++++++++++++++++++---------
drivers/gpu/drm/ast/ast_reg.h | 1 +
2 files changed, 31 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 445cf47871a43..2c2700256a966 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -444,22 +444,42 @@ struct ast_device *ast_device_create(const struct
drm_driver *drv,
if (!ast->regs)
return ERR_PTR(-EIO);
- /*
- * After AST2500, MMIO is enabled by default, and it should be adopted
- * to be compatible with Arm.
- */
if (pdev->revision >= 0x40) {
+ /*
+ * On AST2500 and later models, MMIO is enabled by
+ * default. Adopt it to be compatible with ARM.
+ */
+ resource_size_t len = pci_resource_len(pdev, 1);
+
+ if (len < AST_IO_MM_OFFSET)
+ return ERR_PTR(-EIO);
+ if ((len - AST_IO_MM_OFFSET) < AST_IO_MM_LENGTH)
+ return ERR_PTR(-EIO);
ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
- } else if (!(pci_resource_flags(pdev, 2) & IORESOURCE_IO)) {
- drm_info(dev, "platform has no IO space, trying MMIO\n");
- ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
- }
+ } else if (pci_resource_flags(pdev, 2) & IORESOURCE_IO) {
+ /*
+ * Map I/O registers if we have a PCI BAR for I/O.
+ */
+ resource_size_t len = pci_resource_len(pdev, 2);
- /* "map" IO regs if the above hasn't done so already */
- if (!ast->ioregs) {
+ if ((len - AST_IO_MM_OFFSET) < AST_IO_MM_LENGTH)
+ return ERR_PTR(-EIO);
ast->ioregs = pcim_iomap(pdev, 2, 0);
if (!ast->ioregs)
return ERR_PTR(-EIO);
+ } else {
+ /*
+ * Anything else is best effort.
+ */
+ resource_size_t len = pci_resource_len(pdev, 1);
+
+ if (len < AST_IO_MM_OFFSET)
+ return ERR_PTR(-EIO);
+ if ((len - AST_IO_MM_OFFSET) < AST_IO_MM_LENGTH)
+ return ERR_PTR(-EIO);
+ ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
+
+ drm_info(dev, "Platform has no I/O space, using MMIO\n");
}
if (!ast_is_vga_enabled(dev)) {
diff --git a/drivers/gpu/drm/ast/ast_reg.h b/drivers/gpu/drm/ast/ast_reg.h
index 555286ecf5209..f1e1700c01ed2 100644
--- a/drivers/gpu/drm/ast/ast_reg.h
+++ b/drivers/gpu/drm/ast/ast_reg.h
@@ -10,6 +10,7 @@
*/
#define AST_IO_MM_OFFSET (0x380)
+#define AST_IO_MM_LENGTH (0xff)
#define AST_IO_VGAARI_W (0x40)
#define AST_IO_VGAMR_W (0x42)
--
2.42.0
