From 1c680f2acdbb3b64965962ca060a6daa6379575d Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:50 +0200 Subject: [PATCH] PCI: Add pci_rebar_get_max_size() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add pci_rebar_get_max_size() to allow simplifying code that wants to know the maximum possible size for a Resizable BAR. Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Link: https://patch.msgid.link/20251113180053.27944-9-ilpo.jarvinen@linux.intel.com --- drivers/pci/rebar.c | 23 +++++++++++++++++++++++ include/linux/pci.h | 1 + 2 files changed, 24 insertions(+) diff --git a/drivers/pci/rebar.c b/drivers/pci/rebar.c index 1c90b606b8d4..e99b89bd5e51 100644 --- a/drivers/pci/rebar.c +++ b/drivers/pci/rebar.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -142,6 +143,28 @@ bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size) } EXPORT_SYMBOL_GPL(pci_rebar_size_supported); +/** + * pci_rebar_get_max_size - get the maximum supported size of a BAR + * @pdev: PCI device + * @bar: BAR to query + * + * Get the largest supported size of a resizable BAR as a size. + * + * Return: the encoded maximum BAR size as defined in the PCIe spec + * (0=1MB, 31=128TB), or %-NOENT on error. + */ +int pci_rebar_get_max_size(struct pci_dev *pdev, int bar) +{ + u32 sizes; + + sizes = pci_rebar_get_possible_sizes(pdev, bar); + if (!sizes) + return -ENOENT; + + return __fls(sizes); +} +EXPORT_SYMBOL_GPL(pci_rebar_get_max_size); + /** * pci_rebar_get_current_size - get the current size of a Resizable BAR * @pdev: PCI device diff --git a/include/linux/pci.h b/include/linux/pci.h index 0ef827cfaf0c..898bc3a4e8e7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1425,6 +1425,7 @@ int pci_rebar_bytes_to_size(u64 bytes); resource_size_t pci_rebar_size_to_bytes(int size); u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size); +int pci_rebar_get_max_size(struct pci_dev *pdev, int bar); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, int exclude_bars); -- 2.47.3