target-ppc: create a helper function to allow more flexible RAM allocation for PPC 4xx

The 4xx SDRAM controller supports a small number of banks, and each bank must
be one of a small set of sizes. The number of banks and the supported sizes
varies by SoC.

This function uses the user-specified RAM size to fill in the "ram_bases" and
"ram_sizes" arrays required by ppc4xx_sdram_init().

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6063 c046a42c-6fe2-441c-8c8c-71466251a162

hw/ppc4xx.h

@@ -48,6 +48,11 @@ enum {
 qemu_irq *ppcuic_init (CPUState *env, qemu_irq *irqs,
                        uint32_t dcr_base, int has_ssr, int has_vr);
 
+ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
+                               target_phys_addr_t ram_bases[],
+                               target_phys_addr_t ram_sizes[],
+                               const unsigned int sdram_bank_sizes[]);
+
 void ppc4xx_sdram_init (CPUState *env, qemu_irq irq, int nbanks,
                         target_phys_addr_t *ram_bases,
                         target_phys_addr_t *ram_sizes,

hw/ppc4xx_devs.c

@@ -873,3 +873,45 @@ void ppc4xx_sdram_init (CPUState *env, qemu_irq irq, int nbanks,
             sdram_map_bcr(sdram);
     }
 }
+
+/* Fill in consecutive SDRAM banks with 'ram_size' bytes of memory.
+ *
+ * sdram_bank_sizes[] must be 0-terminated.
+ *
+ * The 4xx SDRAM controller supports a small number of banks, and each bank
+ * must be one of a small set of sizes. The number of banks and the supported
+ * sizes varies by SoC. */
+ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
+                               target_phys_addr_t ram_bases[],
+                               target_phys_addr_t ram_sizes[],
+                               const unsigned int sdram_bank_sizes[])
+{
+    ram_addr_t ram_end = 0;
+    int i;
+    int j;
+
+    for (i = 0; i < nr_banks; i++) {
+        for (j = 0; sdram_bank_sizes[j] != 0; j++) {
+            unsigned int bank_size = sdram_bank_sizes[j];
+
+            if (bank_size <= ram_size) {
+                ram_bases[i] = ram_end;
+                ram_sizes[i] = bank_size;
+                ram_end += bank_size;
+                ram_size -= bank_size;
+                break;
+            }
+        }
+
+        if (!ram_size) {
+            /* No need to use the remaining banks. */
+            break;
+        }
+    }
+
+    if (ram_size)
+        printf("Truncating memory to %d MiB to fit SDRAM controller limits.\n",
+               (int)(ram_end >> 20));
+
+    return ram_end;
+}