On Fri, Oct 11, 2024 at 09:01:12PM +0900, Damien Le Moal wrote:
> Some endpoint controllers have requirements on the alignment of the
> controller physical memory address that must be used to map a RC PCI
> address region. For instance, the endpoint controller of the RK3399 SoC
> uses at most the lower 20 bits of a physical memory address region as
> the lower bits of a RC PCI address region. For mapping a PCI address
> region of size bytes starting from pci_addr, the exact number of
> address bits used is the number of address bits changing in the address
> range [pci_addr..pci_addr + size - 1]. For this example, this creates
> the following constraints:
> 1) The offset into the controller physical memory allocated for a
> mapping depends on the mapping size *and* the starting PCI address
> for the mapping.
> 2) A mapping size cannot exceed the controller windows size (1MB) minus
> the offset needed into the allocated physical memory, which can end
> up being a smaller size than the desired mapping size.
>
> Handling these constraints independently of the controller being used
> in an endpoint function driver is not possible with the current EPC
> API as only the ->align field in struct pci_epc_features is provided
> but used for BAR (inbound ATU mappings) mapping only. A new API is
> needed for function drivers to discover mapping constraints and handle
> non-static requirements based on the RC PCI address range to access.
>
> Introduce endpoint controller operation ->get_mem_map() to allow
> the EPC core functions to obtain the size and the offset into a
> controller address region that must be allocated and mapped to access
> a RC PCI address region. The size of the mapping provided by the
> get_mem_map() operation can then be used as the size argument for the
> function pci_epc_mem_alloc_addr() and the offset into the allocated
> controller memory provided can be used to correctly handle data
> transfers. For endpoint controllers that have PCI address alignment
> constraints, get_mem_map() may indicate upon return an effective PCI
> address region size that is smaller (but not 0) than the requested PCI
> address region size.
>
> The controller ->get_mem_map() operation is optional: controllers that
> do not have any alignment constraints for mapping RC PCI address regions
> do not need to implement this operation. For such controllers, it is
> always assumed that the mapping size is equal to the requested size of
> the PCI region and that the mapping offset is 0.
>
> The function pci_epc_mem_map() is introduced to use this new controller
> operation (if it is defined) to handle controller memory allocation and
> mapping to a RC PCI address region in endpoint function drivers.
>
> This function first uses the ->get_mem_map() controller operation to
> determine the controller memory address size (and offset into) needed
> for mapping an RC PCI address region. The result of this function
> operation is used to allocate a controller physical memory region using
> pci_epc_mem_alloc_addr() and then to map that memory to the RC PCI
> address space with pci_epc_map_addr().
>
> Since ->get_mem_map() () may indicate that not all of a RC PCI
> address region can be mapped, pci_epc_mem_map() may only partially map
> the RC PCI address region specified. It is the responsibility of the
> caller (an endpoint function driver) to handle such smaller mapping
> by repeatedly using pci_epc_mem_map() over the desried PCI address
> range.
>
> The counterpart of pci_epc_mem_map() to unmap and free the controller
> memory address region is pci_epc_mem_unmap().
>
> Both functions as well as the ->get_mem_map() controller operation
> operate using the new struct pci_epc_map data structure. This new
> structure represents a mapping PCI address, mapping effective size, the
> size and offset into the controller memory needed for the mapping as
> well as the physical and virtual CPU addresses of the mapping (phys_base
> and virt_base fields). For convenience, the physical and virtual CPU
> addresses within that mapping to access the target RC PCI address region
> are also provided (phys_addr and virt_addr fields).
>
> Endpoint function drivers can use struct pci_epc_map to access the
> mapped RC PCI address region using the ->virt_addr and ->pci_size
> fields.
>
> Co-developed-by: Rick Wertenbroek <rick.wertenbroek@xxxxxxxxx>
> Signed-off-by: Rick Wertenbroek <rick.wertenbroek@xxxxxxxxx>
> Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
> ---
> drivers/pci/endpoint/pci-epc-core.c | 126 ++++++++++++++++++++++++++++
> include/linux/pci-epc.h | 39 +++++++++
> 2 files changed, 165 insertions(+)
>
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index b854f1bab26f..b6bf6d9f9f85 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -466,6 +466,132 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> }
> EXPORT_SYMBOL_GPL(pci_epc_map_addr);
>
> +/*
> + * Determine the actual PCI address range that should be mapped to access
> + * @pci_size from @pci_addr. This is done using the controller get_mem_map
> + * operation if that operation is defined. Otherwise, simply assume that the
> + * controller has no mapping alignment constraint and return the requested range
> + * as-is.
> + */
> +static int pci_epc_get_mem_map(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + u64 pci_addr, size_t pci_size,
> + struct pci_epc_map *map)
> +{
> + int ret;
> +
> + /*
> + * Initialize and remember the PCI address region to be mapped. The
> + * controller ->get_mem_map() operation may change the map->pci_size to a
> + * smaller value.
> + */
> + memset(map, 0, sizeof(*map));
> + map->pci_addr = pci_addr;
> + map->pci_size = pci_size;
> +
> + if (!epc->ops->get_mem_map) {
> + /*
> + * Assume that the EP controller has no alignment constraint,
> + * that is, that the PCI address to map and the size of the
> + * controller memory needed for the mapping are the same as
> + * specified by the caller.
> + */
> + map->map_pci_addr = pci_addr;
> + map->map_size = pci_size;
> + map->map_ofst = 0;
> + return 0;
> + }
> +
> + mutex_lock(&epc->lock);
> + ret = epc->ops->get_mem_map(epc, func_no, vfunc_no, map);
> + mutex_unlock(&epc->lock);
> +
> + return ret;
> +}
> +
> +/**
> + * pci_epc_mem_map() - allocate and map a PCI address to a CPU address
> + * @epc: the EPC device on which the CPU address is to be allocated and mapped
> + * @func_no: the physical endpoint function number in the EPC device
> + * @vfunc_no: the virtual endpoint function number in the physical function
> + * @pci_addr: PCI address to which the CPU address should be mapped
> + * @pci_size: the number of bytes to map starting from @pci_addr
> + * @map: where to return the mapping information
> + *
> + * Allocate a controller memory address region and map it to a RC PCI address
> + * region, taking into account the controller physical address mapping
> + * constraints using pci_epc_get_mem_map().
> + * The effective size of the PCI address range mapped from @pci_addr is
> + * indicated by @map->pci_size. This size may be less than the requested
> + * @pci_size. The local virtual CPU address for the mapping is indicated by
> + * @map->virt_addr (@map->phys_addr indicates the physical address).
> + * The size and CPU address of the controller memory allocated and mapped are
> + * respectively indicated by @map->map_size and @map->virt_base (and
> + * @map->phys_base).
> + *
> + * Returns 0 on success and a negative error code in case of error.
> + */
> +int pci_epc_mem_map(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + u64 pci_addr, size_t pci_size, struct pci_epc_map *map)
> +{
> + int ret;
> +
> + if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
> + return -EINVAL;
> +
> + if (!pci_size || !map)
> + return -EINVAL;
> +
> + ret = pci_epc_get_mem_map(epc, func_no, vfunc_no,
> + pci_addr, pci_size, map);
> + if (ret)
> + return ret;
> +
> + map->virt_base = pci_epc_mem_alloc_addr(epc, &map->phys_base,
> + map->map_size);
> + if (!map->virt_base)
> + return -ENOMEM;
> +
> + map->phys_addr = map->phys_base + map->map_ofst;
> + map->virt_addr = map->virt_base + map->map_ofst;
> +
> + ret = pci_epc_map_addr(epc, func_no, vfunc_no, map->phys_base,
> + map->map_pci_addr, map->map_size);
> + if (ret) {
> + pci_epc_mem_free_addr(epc, map->phys_base, map->virt_base,
> + map->map_size);
> + map->virt_base = 0;
As reported by the kernel test robot on both v3 and v4, this should be:
map->virt_base = NULL;
otherwise you introduce a new sparse warning.
> + return ret;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_epc_mem_map);
> +
> +/**
> + * pci_epc_mem_unmap() - unmap and free a CPU address region
> + * @epc: the EPC device on which the CPU address is allocated and mapped
> + * @func_no: the physical endpoint function number in the EPC device
> + * @vfunc_no: the virtual endpoint function number in the physical function
> + * @map: the mapping information
> + *
> + * Unmap and free a CPU address region that was allocated and mapped with
> + * pci_epc_mem_map().
> + */
> +void pci_epc_mem_unmap(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + struct pci_epc_map *map)
> +{
> + if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
> + return;
> +
> + if (!map || !map->virt_base)
> + return;
> +
> + pci_epc_unmap_addr(epc, func_no, vfunc_no, map->phys_base);
> + pci_epc_mem_free_addr(epc, map->phys_base, map->virt_base,
> + map->map_size);
> +}
> +EXPORT_SYMBOL_GPL(pci_epc_mem_unmap);
> +
> /**
> * pci_epc_clear_bar() - reset the BAR
> * @epc: the EPC device for which the BAR has to be cleared
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index 42ef06136bd1..b5f5c1eb54c5 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -32,11 +32,44 @@ pci_epc_interface_string(enum pci_epc_interface_type type)
> }
> }
>
> +/**
> + * struct pci_epc_map - information about EPC memory for mapping a RC PCI
> + * address range
> + * @pci_addr: start address of the RC PCI address range to map
> + * @pci_size: size of the RC PCI address range mapped from @pci_addr
> + * @map_pci_addr: RC PCI address used as the first address mapped (may be lower
> + * than @pci_addr)
> + * @map_size: size of the controller memory needed for mapping the RC PCI address
> + * range @pci_addr..@pci_addr+@pci_size
> + * @map_ofst: offset into the mapped controller memory to access @pci_addr
> + * @phys_base: base physical address of the allocated EPC memory for mapping the
> + * RC PCI address range
> + * @phys_addr: physical address at which @pci_addr is mapped
> + * @virt_base: base virtual address of the allocated EPC memory for mapping the
> + * RC PCI address range
> + * @virt_addr: virtual address at which @pci_addr is mapped
> + */
> +struct pci_epc_map {
> + phys_addr_t pci_addr;
> + size_t pci_size;
> +
> + phys_addr_t map_pci_addr;
> + size_t map_size;
> + phys_addr_t map_ofst;
> +
> + phys_addr_t phys_base;
> + phys_addr_t phys_addr;
> + void __iomem *virt_base;
> + void __iomem *virt_addr;
> +};
> +
> /**
> * struct pci_epc_ops - set of function pointers for performing EPC operations
> * @write_header: ops to populate configuration space header
> * @set_bar: ops to configure the BAR
> * @clear_bar: ops to reset the BAR
> + * @get_mem_map: operation to get the size and offset into a controller memory
> + * window needed to map an RC PCI address region
> * @map_addr: ops to map CPU address to PCI address
> * @unmap_addr: ops to unmap CPU address and PCI address
> * @set_msi: ops to set the requested number of MSI interrupts in the MSI
> @@ -61,6 +94,8 @@ struct pci_epc_ops {
> struct pci_epf_bar *epf_bar);
> void (*clear_bar)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> struct pci_epf_bar *epf_bar);
> + int (*get_mem_map)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + struct pci_epc_map *map);
> int (*map_addr)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> phys_addr_t addr, u64 pci_addr, size_t size);
> void (*unmap_addr)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> @@ -278,6 +313,10 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
> phys_addr_t *phys_addr, size_t size);
> void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
> void __iomem *virt_addr, size_t size);
> +int pci_epc_mem_map(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + u64 pci_addr, size_t pci_size, struct pci_epc_map *map);
> +void pci_epc_mem_unmap(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + struct pci_epc_map *map);
>
> #else
> static inline void pci_epc_init_notify(struct pci_epc *epc)
> --
> 2.47.0
>
