!897 LoongArch: improve dma ops and interrupt process

Merge Pull Request from: @Hongchen_Zhang 
 
1. Add swiotlb backups buffer
2. Add ARCH_HAS_SETUP_DMA_OPS and DMA_OPS
3. pci: irq: Add early_param pci_irq_limit to limit pci irq numbers 
 
Link:https://gitee.com/openeuler/kernel/pulls/897 

Reviewed-by: Guo Dongtai <guodongtai@kylinos.cn> 
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> 

arch/loongarch/Kconfig

@@ -113,6 +113,8 @@ config LOONGARCH
 	select MODULES_USE_ELF_RELA if MODULES
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
 	select NEED_PER_CPU_PAGE_FIRST_CHUNK
+	select DMA_OPS
+	select ARCH_HAS_SETUP_DMA_OPS
 	select OF
 	select OF_EARLY_FLATTREE
 	select PCI

arch/loongarch/include/asm/dma-mapping.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_DMA_MAPPING_H
+#define _ASM_DMA_MAPPING_H
+
+extern const struct dma_map_ops loongson_dma_ops;
+extern bool swiotlb_need_fix;
+extern phys_addr_t io_tlb_start;
+
+static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
+{
+	if (swiotlb_need_fix)
+		return &loongson_dma_ops;
+	else
+		return NULL;
+}
+
+#endif /* _ASM_DMA_MAPPING_H */

drivers/pci/msi.c

@@ -1107,12 +1107,32 @@ int pci_msi_enabled(void)
 }
 EXPORT_SYMBOL(pci_msi_enabled);
 
+#ifdef CONFIG_LOONGARCH
+static unsigned int pci_irq_numbers = 32;
+
+static int __init pci_irq_limit(char *str)
+{
+	get_option(&str, &pci_irq_numbers);
+
+	if (pci_irq_numbers == 0)
+		pci_irq_numbers = 32;
+	return 0;
+}
+
+early_param("pci_irq_limit", pci_irq_limit);
+#endif
+
 static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
 				  struct irq_affinity *affd)
 {
 	int nvec;
 	int rc;
 
+#ifdef CONFIG_LOONGARCH
+	if (maxvec > 32)
+		maxvec = pci_irq_numbers;
+#endif
+
 	if (!pci_msi_supported(dev, minvec) || dev->current_state != PCI_D0)
 		return -EINVAL;
 
@@ -1174,6 +1194,11 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
 {
 	int rc, nvec = maxvec;
 
+#ifdef CONFIG_LOONGARCH
+	if (maxvec > 32)
+		nvec = pci_irq_numbers;
+#endif
+
 	if (maxvec < minvec)
 		return -ERANGE;