x86: Support use of PCI before relocation

Add support for using PCI before SDRAM is available, using early malloc()
and global_data.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/pci.c

@@ -10,15 +10,36 @@
  */
 
 #include <common.h>
+#include <errno.h>
+#include <malloc.h>
 #include <pci.h>
 #include <asm/pci.h>
 
 static struct pci_controller x86_hose;
 
+int pci_early_init_hose(struct pci_controller **hosep)
+{
+	struct pci_controller *hose;
+
+	hose = calloc(1, sizeof(struct pci_controller));
+	if (!hose)
+		return -ENOMEM;
+
+	board_pci_setup_hose(hose);
+	pci_setup_type1(hose);
+	gd->arch.hose = hose;
+	*hosep = hose;
+
+	return 0;
+}
+
 void pci_init_board(void)
 {
 	struct pci_controller *hose = &x86_hose;
 
+	/* Stop using the early hose */
+	gd->arch.hose = NULL;
+
 	board_pci_setup_hose(hose);
 	pci_setup_type1(hose);
 	pci_register_hose(hose);

arch/x86/include/asm/global_data.h

@@ -24,6 +24,7 @@ struct arch_global_data {
 	uint32_t tsc_mhz;		/* TSC frequency in MHz */
 	void *new_fdt;			/* Relocated FDT */
 	uint32_t bist;			/* Built-in self test value */
+	struct pci_controller *hose;	/* PCI hose for early use */
 };
 
 #endif

arch/x86/include/asm/pci.h

@@ -24,4 +24,13 @@ void pci_setup_type1(struct pci_controller *hose);
  * store things in 'hose' and not in BSS variables.
  */
 void board_pci_setup_hose(struct pci_controller *hose);
+
+/**
+ * pci_early_init_hose() - Set up PCI host before relocation
+ *
+ * This allocates memory for, sets up and returns the PCI hose. It can be
+ * called before relocation. The hose will be stored in gd->arch.hose for
+ * later use, but will become invalid one DRAM is available.
+ */
+int pci_early_init_hose(struct pci_controller **hosep);
 #endif