On certain Lenovo/AMD systems, the BIOS declares an ACPI NVS region that covers a large memory range (e.g. 0xccc40000-0xccd3efff) which includes the TPM CRB MMIO area (0xccd35000-0xccd38fff). The E820 subsystem registers this NVS region with IORESOURCE_BUSY in the iomem_resource tree.
When tpm_crb probes, it calls devm_ioremap_resource() to map the CRB registers, which internally calls devm_request_mem_region(). This fails with -EBUSY because the NVS region already claims that address range. Fix this by adding a crb_try_nvs_fallback() helper that detects the ACPI NVS overlap using region_intersects() and falls back to devm_memremap() when the resource falls inside ACPI NVS. devm_memremap() does not require exclusive resource reservation, making it safe to use on NVS-overlapping regions. This approach is identical to the one used by the WDAT watchdog driver (wdat_wdt_map_mem). The NVS fallback is applied in both code paths of crb_map_res(): 1. When iores is NULL (no ACPI resource encompasses the target address) 2. When iores is non-NULL but devm_ioremap_resource() fails with EBUSY Before this patch: tpm_crb MSFT0101:00: error -EBUSY: can't request region for resource [mem 0xccd35000-0xccd38fff] tpm_crb MSFT0101:00: probe with driver tpm_crb failed with error -16 After this patch: tpm_crb MSFT0101:00: [mem 0xccd35000-0xccd38fff] is inside ACPI NVS, mapping without reservation tpm_crb MSFT0101:00: of device registration complete, result 0: 0 Signed-off-by: microfish <[email protected]> Signed-off-by: microfish <[email protected]> --- drivers/char/tpm/tpm_crb.c | 50 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 48 insertions(+), 2 deletions(-) diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index ceb4100ba..c4e8b925c 100644 --- a/drivers/char/tpm/tpm_crb.c +++ b/drivers/char/tpm/tpm_crb.c @@ -13,6 +13,7 @@ #include <linux/acpi.h> #include <linux/highmem.h> +#include <linux/mm.h> #include <linux/rculist.h> #include <linux/module.h> #include <linux/platform_device.h> @@ -557,6 +558,39 @@ static int crb_check_resource(struct acpi_resource *ares, void *data) return 1; } +/* + * Try to map a resource region. If devm_ioremap_resource() fails with + * -EBUSY because the region falls inside an ACPI NVS area (common on + * certain Lenovo/AMD firmware), fall back to devm_memremap() which + * does not require exclusive resource reservation. This is analogous + * to the approach used by the WDAT watchdog driver (wdat_wdt_map_mem). + */ +static void __iomem *crb_try_nvs_fallback(struct device *dev, u64 start, + u32 size) +{ + struct resource res = { + .start = start, + .end = start + size - 1, + .flags = IORESOURCE_MEM, + }; + void *addr; + + if (region_intersects(res.start, resource_size(&res), IORESOURCE_MEM, + IORES_DESC_ACPI_NV_STORAGE) != + REGION_INTERSECTS) + return NULL; + + dev_warn(dev, + "%pR is inside ACPI NVS, mapping without reservation\n", + &res); + + addr = devm_memremap(dev, res.start, resource_size(&res), MEMREMAP_WB); + if (IS_ERR(addr)) + return IOMEM_ERR_PTR(PTR_ERR(addr)); + + return (void __iomem __force *)addr; +} + static void __iomem *crb_map_res(struct device *dev, struct resource *iores, void __iomem **iobase_ptr, u64 start, u32 size) { @@ -565,18 +599,30 @@ static void __iomem *crb_map_res(struct device *dev, struct resource *iores, .end = start + size - 1, .flags = IORESOURCE_MEM, }; + void __iomem *p; /* Detect a 64 bit address on a 32 bit system */ if (start != new_res.start) return IOMEM_ERR_PTR(-EINVAL); - if (!iores) + if (!iores) { + p = crb_try_nvs_fallback(dev, start, size); + if (p) + return p; return devm_ioremap_resource(dev, &new_res); + } if (!*iobase_ptr) { *iobase_ptr = devm_ioremap_resource(dev, iores); - if (IS_ERR(*iobase_ptr)) + if (IS_ERR(*iobase_ptr)) { + p = crb_try_nvs_fallback(dev, iores->start, + resource_size(iores)); + if (p) { + *iobase_ptr = p; + return p + (new_res.start - iores->start); + } return *iobase_ptr; + } } return *iobase_ptr + (new_res.start - iores->start); -- 2.47.3
