Re: [v2 2/6] pci: endpoint: add support to handle features of outbound memory

[Kishon Vijay Abraham I]

Hi Prabhakar,

On 13/12/19 2:17 pm,  wrote:
> From: "Lad, Prabhakar" <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> rcar pcie controller has support to map multiple memory regions
> for mapping the outbound memory in local system, this feature
> inspires to add support for handling such features in endpoint
> framework. similar features exists on other controllers where
> outbound regions can be specifically used for low/high priority
> transactions, and regions can be flagged and used for allocation
> of large/small memory allocations.
> This patch adds support to handle such features, where the
> properties described for outbound regions are used whenever a
> request to memory is made.
>
> Signed-off-by: Lad, Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
>   drivers/pci/controller/dwc/pcie-designware-ep.c |  30 ++--
>   drivers/pci/controller/pcie-cadence-ep.c        |  11 +-
>   drivers/pci/controller/pcie-rockchip-ep.c       |  13 +-
>   drivers/pci/endpoint/functions/pci-epf-test.c   |  47 ++++--
>   drivers/pci/endpoint/pci-epc-core.c             |   7 +-
>   drivers/pci/endpoint/pci-epc-mem.c              | 216 +++++++++++++++++++-----
>   include/linux/pci-epc.h                         |  72 ++++++--
>   7 files changed, 307 insertions(+), 89 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 3dd2e26..be6aa94 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -195,7 +195,7 @@ static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, u8 func_no,
>   }
>   
>   static int dw_pcie_ep_map_addr(struct pci_epc *epc, u8 func_no,
> -			       phys_addr_t addr,
> +			       phys_addr_t addr, int window,
>   			       u64 pci_addr, size_t size)
>   {
>   	int ret;
> @@ -367,6 +367,7 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
>   	unsigned int aligned_offset;
>   	u16 msg_ctrl, msg_data;
>   	u32 msg_addr_lower, msg_addr_upper, reg;
> +	int window = PCI_EPC_DEFAULT_WINDOW;
>   	u64 msg_addr;
>   	bool has_upper;
>   	int ret;
> @@ -390,11 +391,11 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
>   		reg = ep->msi_cap + PCI_MSI_DATA_32;
>   		msg_data = dw_pcie_readw_dbi(pci, reg);
>   	}
> -	aligned_offset = msg_addr_lower & (epc->mem->page_size - 1);
> +	aligned_offset = msg_addr_lower & (epc->mem[window]->page_size - 1);
>   	msg_addr = ((u64)msg_addr_upper) << 32 |
>   			(msg_addr_lower & ~aligned_offset);
> -	ret = dw_pcie_ep_map_addr(epc, func_no, ep->msi_mem_phys, msg_addr,
> -				  epc->mem->page_size);
> +	ret = dw_pcie_ep_map_addr(epc, func_no, ep->msi_mem_phys, window,
> +				  msg_addr, epc->mem[window]->page_size);
>   	if (ret)
>   		return ret;
>   
> @@ -416,6 +417,7 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
>   	u32 reg, msg_data, vec_ctrl;
>   	u64 tbl_addr, msg_addr, reg_u64;
>   	void __iomem *msix_tbl;
> +	int window = PCI_EPC_DEFAULT_WINDOW;
>   	int ret;
>   
>   	reg = ep->msix_cap + PCI_MSIX_TABLE;
> @@ -452,8 +454,8 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
>   		return -EPERM;
>   	}
>   
> -	ret = dw_pcie_ep_map_addr(epc, func_no, ep->msi_mem_phys, msg_addr,
> -				  epc->mem->page_size);
> +	ret = dw_pcie_ep_map_addr(epc, func_no, ep->msi_mem_phys, window,
> +				  msg_addr, epc->mem[window]->page_size);
>   	if (ret)
>   		return ret;
>   
> @@ -466,10 +468,11 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
>   
>   void dw_pcie_ep_exit(struct dw_pcie_ep *ep)
>   {
> +	int window = PCI_EPC_DEFAULT_WINDOW;
>   	struct pci_epc *epc = ep->epc;
>   
>   	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
> -			      epc->mem->page_size);
> +			      epc->mem[window]->page_size);
>   
>   	pci_epc_mem_exit(epc);
>   }
> @@ -499,9 +502,12 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>   	u32 reg;
>   	void *addr;
>   	u8 hdr_type;
> +	int window;
>   	unsigned int nbars;
>   	unsigned int offset;
>   	struct pci_epc *epc;
> +	size_t msi_page_size;
> +	struct pci_epc_mem_window mem_window;
>   	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>   	struct device *dev = pci->dev;
>   	struct device_node *np = dev->of_node;
> @@ -574,15 +580,17 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>   	if (ret < 0)
>   		epc->max_functions = 1;
>   
> -	ret = __pci_epc_mem_init(epc, ep->phys_base, ep->addr_size,
> -				 ep->page_size);
> +	mem_window.phys_base = ep->phys_base;
> +	mem_window.size = ep->addr_size;
> +	ret = __pci_epc_mem_init(epc, &mem_window, 1, ep->page_size);
>   	if (ret < 0) {
>   		dev_err(dev, "Failed to initialize address space\n");
>   		return ret;
>   	}
>   
> -	ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys,
> -					     epc->mem->page_size);
> +	msi_page_size = epc->mem[PCI_EPC_DEFAULT_WINDOW]->page_size;
> +	ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys, &window,
> +					     msi_page_size, 0x0);
>   	if (!ep->msi_mem) {
>   		dev_err(dev, "Failed to reserve memory for MSI/MSI-X\n");
>   		return -ENOMEM;
> diff --git a/drivers/pci/controller/pcie-cadence-ep.c b/drivers/pci/controller/pcie-cadence-ep.c
> index def7820..2410706 100644
> --- a/drivers/pci/controller/pcie-cadence-ep.c
> +++ b/drivers/pci/controller/pcie-cadence-ep.c
> @@ -172,7 +172,7 @@ static void cdns_pcie_ep_clear_bar(struct pci_epc *epc, u8 fn,
>   }
>   
>   static int cdns_pcie_ep_map_addr(struct pci_epc *epc, u8 fn, phys_addr_t addr,
> -				 u64 pci_addr, size_t size)
> +				 int window, u64 pci_addr, size_t size)
>   {
>   	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
>   	struct cdns_pcie *pcie = &ep->pcie;
> @@ -434,12 +434,14 @@ static int cdns_pcie_ep_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
>   	struct device_node *np = dev->of_node;
> +	struct pci_epc_mem_window mem_window;
>   	struct cdns_pcie_ep *ep;
>   	struct cdns_pcie *pcie;
>   	struct pci_epc *epc;
>   	struct resource *res;
>   	int ret;
>   	int phy_count;
> +	int window;
>   
>   	ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
>   	if (!ep)
> @@ -502,15 +504,16 @@ static int cdns_pcie_ep_probe(struct platform_device *pdev)
>   	if (of_property_read_u8(np, "max-functions", &epc->max_functions) < 0)
>   		epc->max_functions = 1;
>   
> -	ret = pci_epc_mem_init(epc, pcie->mem_res->start,
> -			       resource_size(pcie->mem_res));
> +	mem_window.phys_base = pcie->mem_res->start;
> +	mem_window.size = resource_size(pcie->mem_res);
> +	ret = pci_epc_mem_init(epc, &mem_window, 1);
>   	if (ret < 0) {
>   		dev_err(dev, "failed to initialize the memory space\n");
>   		goto err_init;
>   	}
>   
>   	ep->irq_cpu_addr = pci_epc_mem_alloc_addr(epc, &ep->irq_phys_addr,
> -						  SZ_128K);
> +						  &window, SZ_128K, 0x0);
>   	if (!ep->irq_cpu_addr) {
>   		dev_err(dev, "failed to reserve memory space for MSI\n");
>   		ret = -ENOMEM;
> diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
> index d743b0a..828052c 100644
> --- a/drivers/pci/controller/pcie-rockchip-ep.c
> +++ b/drivers/pci/controller/pcie-rockchip-ep.c
> @@ -256,8 +256,8 @@ static void rockchip_pcie_ep_clear_bar(struct pci_epc *epc, u8 fn,
>   }
>   
>   static int rockchip_pcie_ep_map_addr(struct pci_epc *epc, u8 fn,
> -				     phys_addr_t addr, u64 pci_addr,
> -				     size_t size)
> +				     phys_addr_t addr, int window,
> +				     u64 pci_addr, size_t size)
>   {
>   	struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
>   	struct rockchip_pcie *pcie = &ep->rockchip;
> @@ -562,11 +562,13 @@ static const struct of_device_id rockchip_pcie_ep_of_match[] = {
>   
>   static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>   {
> +	struct pci_epc_mem_window mem_window;
>   	struct device *dev = &pdev->dev;
>   	struct rockchip_pcie_ep *ep;
>   	struct rockchip_pcie *rockchip;
>   	struct pci_epc *epc;
>   	size_t max_regions;
> +	int window;
>   	int err;
>   
>   	ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
> @@ -614,15 +616,16 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>   	/* Only enable function 0 by default */
>   	rockchip_pcie_write(rockchip, BIT(0), PCIE_CORE_PHY_FUNC_CFG);
>   
> -	err = pci_epc_mem_init(epc, rockchip->mem_res->start,
> -			       resource_size(rockchip->mem_res));
> +	mem_window.phys_base = rockchip->mem_res->start;
> +	mem_window.size = resource_size(rockchip->mem_res);
> +	err = pci_epc_mem_init(epc, &mem_window, 1);
>   	if (err < 0) {
>   		dev_err(dev, "failed to initialize the memory space\n");
>   		goto err_uninit_port;
>   	}
>   
>   	ep->irq_cpu_addr = pci_epc_mem_alloc_addr(epc, &ep->irq_phys_addr,
> -						  SZ_128K);
> +						  &window, SZ_128K, 0x0);
>   	if (!ep->irq_cpu_addr) {
>   		dev_err(dev, "failed to reserve memory space for MSI\n");
>   		err = -ENOMEM;
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 1cfe368..4768d54 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -84,8 +84,14 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
>   	struct pci_epc *epc = epf->epc;
>   	enum pci_barno test_reg_bar = epf_test->test_reg_bar;
>   	struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> -
> -	src_addr = pci_epc_mem_alloc_addr(epc, &src_phys_addr, reg->size);
> +	int window;
> +
> +	src_addr = pci_epc_mem_alloc_addr(epc, &src_phys_addr,
> +					  &window, reg->size,
> +					  PCI_EPC_WINDOW_FLAG_LARGE_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_SMALL_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_HIGH_PRI_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_LOW_PRI_ALLOC);
>   	if (!src_addr) {
>   		dev_err(dev, "Failed to allocate source address\n");
>   		reg->status = STATUS_SRC_ADDR_INVALID;
> @@ -93,15 +99,20 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
>   		goto err;
>   	}
>   
> -	ret = pci_epc_map_addr(epc, epf->func_no, src_phys_addr, reg->src_addr,
> -			       reg->size);
> +	ret = pci_epc_map_addr(epc, epf->func_no, src_phys_addr, window,
> +			       reg->src_addr, reg->size);
>   	if (ret) {
>   		dev_err(dev, "Failed to map source address\n");
>   		reg->status = STATUS_SRC_ADDR_INVALID;
>   		goto err_src_addr;
>   	}
>   
> -	dst_addr = pci_epc_mem_alloc_addr(epc, &dst_phys_addr, reg->size);
> +	dst_addr = pci_epc_mem_alloc_addr(epc, &dst_phys_addr,
> +					  &window, reg->size,
> +					  PCI_EPC_WINDOW_FLAG_LARGE_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_SMALL_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_HIGH_PRI_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_LOW_PRI_ALLOC);
>   	if (!dst_addr) {
>   		dev_err(dev, "Failed to allocate destination address\n");
>   		reg->status = STATUS_DST_ADDR_INVALID;
> @@ -109,8 +120,8 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
>   		goto err_src_map_addr;
>   	}
>   
> -	ret = pci_epc_map_addr(epc, epf->func_no, dst_phys_addr, reg->dst_addr,
> -			       reg->size);
> +	ret = pci_epc_map_addr(epc, epf->func_no, dst_phys_addr, window,
> +			       reg->dst_addr, reg->size);
>   	if (ret) {
>   		dev_err(dev, "Failed to map destination address\n");
>   		reg->status = STATUS_DST_ADDR_INVALID;
> @@ -146,8 +157,13 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
>   	struct pci_epc *epc = epf->epc;
>   	enum pci_barno test_reg_bar = epf_test->test_reg_bar;
>   	struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> +	int window;
>   
> -	src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> +	src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, &window, reg->size,
> +					  PCI_EPC_WINDOW_FLAG_LARGE_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_SMALL_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_HIGH_PRI_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_LOW_PRI_ALLOC);
>   	if (!src_addr) {
>   		dev_err(dev, "Failed to allocate address\n");
>   		reg->status = STATUS_SRC_ADDR_INVALID;
> @@ -155,8 +171,8 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
>   		goto err;
>   	}
>   
> -	ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, reg->src_addr,
> -			       reg->size);
> +	ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, window,
> +			       reg->src_addr, reg->size);
>   	if (ret) {
>   		dev_err(dev, "Failed to map address\n");
>   		reg->status = STATUS_SRC_ADDR_INVALID;
> @@ -193,13 +209,18 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
>   	void __iomem *dst_addr;
>   	void *buf;
>   	phys_addr_t phys_addr;
> +	int window;
>   	struct pci_epf *epf = epf_test->epf;
>   	struct device *dev = &epf->dev;
>   	struct pci_epc *epc = epf->epc;
>   	enum pci_barno test_reg_bar = epf_test->test_reg_bar;
>   	struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
>   
> -	dst_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> +	dst_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, &window, reg->size,
> +					  PCI_EPC_WINDOW_FLAG_LARGE_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_SMALL_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_HIGH_PRI_ALLOC |
> +					  PCI_EPC_WINDOW_FLAG_LOW_PRI_ALLOC);
>   	if (!dst_addr) {
>   		dev_err(dev, "Failed to allocate address\n");
>   		reg->status = STATUS_DST_ADDR_INVALID;
> @@ -207,8 +228,8 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
>   		goto err;
>   	}
>   
> -	ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, reg->dst_addr,
> -			       reg->size);
> +	ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, window,
> +			       reg->dst_addr, reg->size);
>   	if (ret) {
>   		dev_err(dev, "Failed to map address\n");
>   		reg->status = STATUS_DST_ADDR_INVALID;
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index 2091508..289c266 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -358,13 +358,15 @@ EXPORT_SYMBOL_GPL(pci_epc_unmap_addr);
>    * @epc: the EPC device on which address is allocated
>    * @func_no: the endpoint function number in the EPC device
>    * @phys_addr: physical address of the local system
> + * @window: index to the window region where PCI address will be mapped
>    * @pci_addr: PCI address to which the physical address should be mapped
>    * @size: the size of the allocation
>    *
>    * Invoke to map CPU address with PCI address.
>    */
>   int pci_epc_map_addr(struct pci_epc *epc, u8 func_no,
> -		     phys_addr_t phys_addr, u64 pci_addr, size_t size)
> +		     phys_addr_t phys_addr, int window,
> +		     u64 pci_addr, size_t size)
>   {
>   	int ret;
>   	unsigned long flags;
> @@ -376,7 +378,8 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no,
>   		return 0;
>   
>   	spin_lock_irqsave(&epc->lock, flags);
> -	ret = epc->ops->map_addr(epc, func_no, phys_addr, pci_addr, size);
> +	ret = epc->ops->map_addr(epc, func_no, phys_addr,
> +				 window, pci_addr, size);
>   	spin_unlock_irqrestore(&epc->lock, flags);
>   
>   	return ret;
> diff --git a/drivers/pci/endpoint/pci-epc-mem.c b/drivers/pci/endpoint/pci-epc-mem.c
> index 2bf8bd1..4b610cd 100644
> --- a/drivers/pci/endpoint/pci-epc-mem.c
> +++ b/drivers/pci/endpoint/pci-epc-mem.c
> @@ -39,56 +39,78 @@ static int pci_epc_mem_get_order(struct pci_epc_mem *mem, size_t size)
>    * __pci_epc_mem_init() - initialize the pci_epc_mem structure
>    * @epc: the EPC device that invoked pci_epc_mem_init
>    * @phys_base: the physical address of the base
> - * @size: the size of the address space
> + * @num_windows: number of windows device supports
>    * @page_size: size of each page
>    *
>    * Invoke to initialize the pci_epc_mem structure used by the
>    * endpoint functions to allocate mapped PCI address.
>    */
> -int __pci_epc_mem_init(struct pci_epc *epc, phys_addr_t phys_base, size_t size,
> -		       size_t page_size)
> +int __pci_epc_mem_init(struct pci_epc *epc, struct pci_epc_mem_window *windows,
> +		       int num_windows, size_t page_size)
>   {
> -	int ret;
> -	struct pci_epc_mem *mem;
> -	unsigned long *bitmap;
> +	struct pci_epc_mem *mem = NULL;
> +	unsigned long *bitmap = NULL;
>   	unsigned int page_shift;
> -	int pages;
>   	int bitmap_size;
> +	int pages;
> +	int ret;
> +	int i;
> +
> +	epc->mem_windows = 0;
> +
> +	if (!windows)
> +		return -EINVAL;
> +
> +	if (num_windows <= 0)
> +		return -EINVAL;
>   
>   	if (page_size < PAGE_SIZE)
>   		page_size = PAGE_SIZE;
>   
>   	page_shift = ilog2(page_size);
> -	pages = size >> page_shift;
> -	bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
>   
> -	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> -	if (!mem) {
> -		ret = -ENOMEM;
> -		goto err;
> -	}
> +	epc->mem = kcalloc(num_windows, sizeof(*mem), GFP_KERNEL);
> +	if (!epc->mem)
> +		return -EINVAL;
>   
> -	bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> -	if (!bitmap) {
> -		ret = -ENOMEM;
> -		goto err_mem;
> -	}
> +	for (i = 0; i < num_windows; i++) {
> +		pages = windows[i].phys_base >> page_shift;
> +		bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
>   
> -	mem->bitmap = bitmap;
> -	mem->phys_base = phys_base;
> -	mem->page_size = page_size;
> -	mem->pages = pages;
> -	mem->size = size;
> +		mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> +		if (!mem) {
> +			ret = -ENOMEM;
> +			goto err_mem;
> +		}
>   
> -	epc->mem = mem;
> +		bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> +		if (!bitmap) {
> +			ret = -ENOMEM;
> +			goto err_mem;
> +		}
> +
> +		mem->bitmap = bitmap;
> +		mem->window.phys_base = windows[i].phys_base;
> +		mem->page_size = page_size;
> +		mem->pages = pages;
> +		mem->window.size = windows[i].size;
> +		mem->window.map_size = 0;
> +		mem->window.flags = windows[i].flags;
> +
> +		epc->mem[i] = mem;
> +	}
> +	epc->mem_windows = num_windows;
>   
>   	return 0;
>   
>   err_mem:
> -	kfree(mem);
> +	for (; i >= 0; i--) {
> +		kfree(mem->bitmap);
> +		kfree(epc->mem[i]);
> +	}
> +	kfree(epc->mem);
>   
> -err:
> -return ret;
> +	return ret;
>   }
>   EXPORT_SYMBOL_GPL(__pci_epc_mem_init);
>   
> @@ -101,48 +123,152 @@ EXPORT_SYMBOL_GPL(__pci_epc_mem_init);
>    */
>   void pci_epc_mem_exit(struct pci_epc *epc)
>   {
> -	struct pci_epc_mem *mem = epc->mem;
> +	struct pci_epc_mem *mem;
> +	int i;
> +
> +	if (!epc->mem_windows)
> +		return;
> +
> +	for (i = 0; i <= epc->mem_windows; i--) {
> +		mem = epc->mem[i];
> +		kfree(mem->bitmap);
> +		kfree(epc->mem[i]);
> +	}
> +	kfree(epc->mem);
>   
>   	epc->mem = NULL;
> -	kfree(mem->bitmap);
> -	kfree(mem);
> +	epc->mem_windows = 0;
>   }
>   EXPORT_SYMBOL_GPL(pci_epc_mem_exit);
>   
> +static int pci_epc_find_best_fit_window(struct pci_epc *epc, size_t size,
> +					u32 flags)
> +{
> +	size_t window_least_size = 0;
> +	int best_fit_window = -1;
> +	struct pci_epc_mem *mem;
> +	size_t actual_size;
> +	size_t avail_size;
> +	u32 win_flags;
> +	int i;
> +
> +	for (i = 0; i < epc->mem_windows; i++) {
> +		mem = epc->mem[i];
> +		win_flags = mem->window.flags;
> +
> +		actual_size = ALIGN(size, mem->page_size);
> +		avail_size = mem->window.size - mem->window.map_size;
> +
> +		if (win_flags == 0x0) {
> +			if (best_fit_window == -1) {
> +				if (actual_size <= avail_size) {
> +					best_fit_window = i;
> +					window_least_size = mem->window.size;
> +				}
> +			} else {
> +				if (actual_size <= avail_size &&
> +				    mem->window.size < window_least_size) {
> +					best_fit_window = i;
> +					window_least_size = mem->window.size;
> +				}
> +			}
> +		} else {
> +			if (mem->window.map_size &&
> +			    (win_flags | PCI_EPC_WINDOW_FLAG_NON_MULTI_ALLOC))
> +				continue;
> +
> +			if (!(win_flags | flags))
> +				continue;
> +
> +			if (best_fit_window == -1) {
> +				if (actual_size <= avail_size) {
> +					best_fit_window = i;
> +					window_least_size = mem->window.size;
> +				}
> +			} else {
> +				if (actual_size <= avail_size &&
> +				    mem->window.size < window_least_size) {
> +					best_fit_window = i;
> +					window_least_size = mem->window.size;
> +				}
> +			}
> +		}
> +	}
> +
> +	return best_fit_window;
> +}
> +
>   /**
>    * pci_epc_mem_alloc_addr() - allocate memory address from EPC addr space
>    * @epc: the EPC device on which memory has to be allocated
>    * @phys_addr: populate the allocated physical address here
> + * @window: populate the window here which will be used to map PCI address
>    * @size: the size of the address space that has to be allocated
> + * @flags: look for window as requested in flags
>    *
>    * Invoke to allocate memory address from the EPC address space. This
>    * is usually done to map the remote RC address into the local system.
>    */
>   void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
> -				     phys_addr_t *phys_addr, size_t size)
> +				     phys_addr_t *phys_addr,
> +				     int *window, size_t size, uint32_t flags)
>   {
> +	int best_fit = PCI_EPC_DEFAULT_WINDOW;
> +	void __iomem *virt_addr = NULL;
> +	struct pci_epc_mem *mem;
> +	unsigned int page_shift;
>   	int pageno;
> -	void __iomem *virt_addr;
> -	struct pci_epc_mem *mem = epc->mem;
> -	unsigned int page_shift = ilog2(mem->page_size);
>   	int order;
>   
> +	if (epc->mem_windows <= 0)
> +		return NULL;
> +
> +	if (epc->mem_windows > 1) {
> +		best_fit = pci_epc_find_best_fit_window(epc, size, flags);
> +		if (best_fit < 0)
> +			return NULL;
> +	}
> +
> +	mem = epc->mem[best_fit];
>   	size = ALIGN(size, mem->page_size);
> +	if (size > (mem->window.size - mem->window.map_size))
> +		return NULL;
> +	page_shift = ilog2(mem->page_size);
>   	order = pci_epc_mem_get_order(mem, size);
>   
>   	pageno = bitmap_find_free_region(mem->bitmap, mem->pages, order);
>   	if (pageno < 0)
>   		return NULL;
>   
> -	*phys_addr = mem->phys_base + (pageno << page_shift);
> +	*phys_addr = mem->window.phys_base + (pageno << page_shift);
>   	virt_addr = ioremap(*phys_addr, size);
> -	if (!virt_addr)
> +	if (!virt_addr) {
>   		bitmap_release_region(mem->bitmap, pageno, order);
> +	} else {
> +		mem->window.map_size += size;
> +		*window = best_fit;
> +	}
>   
>   	return virt_addr;
>   }
>   EXPORT_SYMBOL_GPL(pci_epc_mem_alloc_addr);
>   
> +static int pci_epc_get_matching_window(struct pci_epc *epc,
> +				       phys_addr_t phys_addr)
> +{
> +	struct pci_epc_mem *mem;
> +	int i;
> +
> +	for (i = 0; i < epc->mem_windows; i++) {
> +		mem = epc->mem[i];
> +
> +		if (mem->window.phys_base == phys_addr)
> +			return i;
> +	}
> +
> +	return -EINVAL;
> +}
> +
>   /**
>    * pci_epc_mem_free_addr() - free the allocated memory address
>    * @epc: the EPC device on which memory was allocated
> @@ -155,16 +281,26 @@ EXPORT_SYMBOL_GPL(pci_epc_mem_alloc_addr);
>   void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
>   			   void __iomem *virt_addr, size_t size)
>   {
> +	struct pci_epc_mem *mem;
> +	unsigned int page_shift;
> +	int window = 0;
>   	int pageno;
> -	struct pci_epc_mem *mem = epc->mem;
> -	unsigned int page_shift = ilog2(mem->page_size);
>   	int order;
>   
> +	if (epc->mem_windows > 1) {
> +		window = pci_epc_get_matching_window(epc, phys_addr);
> +		if (window < 0)
> +			return;
> +	}
> +
> +	mem = epc->mem[window];
> +	page_shift = ilog2(mem->page_size);
>   	iounmap(virt_addr);
> -	pageno = (phys_addr - mem->phys_base) >> page_shift;
> +	pageno = (phys_addr - mem->window.phys_base) >> page_shift;
>   	size = ALIGN(size, mem->page_size);
>   	order = pci_epc_mem_get_order(mem, size);
>   	bitmap_release_region(mem->bitmap, pageno, order);
> +	mem->window.map_size -= size;
>   }
>   EXPORT_SYMBOL_GPL(pci_epc_mem_free_addr);
>   
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index f641bad..bee6f65 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -48,7 +48,8 @@ struct pci_epc_ops {
>   	void	(*clear_bar)(struct pci_epc *epc, u8 func_no,
>   			     struct pci_epf_bar *epf_bar);
>   	int	(*map_addr)(struct pci_epc *epc, u8 func_no,
> -			    phys_addr_t addr, u64 pci_addr, size_t size);
> +			    phys_addr_t addr, int window,
> +			    u64 pci_addr, size_t size);
>   	void	(*unmap_addr)(struct pci_epc *epc, u8 func_no,
>   			      phys_addr_t addr);
>   	int	(*set_msi)(struct pci_epc *epc, u8 func_no, u8 interrupts);
> @@ -64,17 +65,57 @@ struct pci_epc_ops {
>   	struct module *owner;
>   };
>   
> +#define PCI_EPC_DEFAULT_WINDOW		0
> +
> +/**
> + * enum pci_epc_window_flags - flags info for pci_epc_mem_window
> + *
> + * This enum defines how the endpoint controller window should be used
> + * for allocations.
> + *
> + * @PCI_EPC_WINDOW_FLAG_MULTI_ALLOC: Indicates multiple chunks of memory can be
> + *				     allocated from same window
> + * @PCI_EPC_WINDOW_FLAG_NON_MULTI_ALLOC: Indicates only single memory allocation
> + *					 is possible on the window

Instead of NON_MULTI_ALLOC, we could simply have different page_size for 
different windows. For a platform that doesn't allow multiple alloc, 
page size will be equal to the window size.
> + * @PCI_EPC_WINDOW_FLAG_LARGE_ALLOC: Window is used for large memory allocation
> + * @PCI_EPC_WINDOW_FLAG_SMALL_ALLOC: Window is used for small memory allocation
> + * @PCI_EPC_WINDOW_FLAG_HIGH_PRI_ALLOC: Window is used for high priority data
> + *					transfers
> + * @PCI_EPC_WINDOW_FLAG_LOW_PRI_ALLOC: Window is used for low priority data
> + *				       transfers

Let's defer adding these flags until a platform actually starts to use this.

Thanks
Kishon