drive_get_next() is basically a bad idea.  It returns the "next" block
backend of a certain interface type.  "Next" means bus=0,unit=N, where
subsequent calls count N up from zero, per interface type.

This lets you define unit numbers implicitly by execution order.  If the
order changes, or new calls appear "in the middle", unit numbers change.
ABI break.  Hard to spot in review.

The aspeed machines connects backends with drive_get_next() in several
counting loops, one of them in a helper function, and a conditional.
Change it to use drive_get() directly.  This makes the unit numbers
explicit in the code.

Cc: "Cédric Le Goater" <clg@kaod.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Joel Stanley <joel@jms.id.au>
Cc: qemu-arm@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20211117163409.3587705-13-armbru@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
---
 hw/arm/aspeed.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index a77f46b3ad..cf20ae0db5 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -284,12 +284,13 @@ static void write_boot_rom(DriveInfo *dinfo, hwaddr addr, size_t rom_size,
 }
 
 static void aspeed_board_init_flashes(AspeedSMCState *s,
-                                      const char *flashtype)
+                                      const char *flashtype,
+                                      int unit0)
 {
     int i ;
 
     for (i = 0; i < s->num_cs; ++i) {
-        DriveInfo *dinfo = drive_get_next(IF_MTD);
+        DriveInfo *dinfo = drive_get(IF_MTD, 0, unit0 + i);
         qemu_irq cs_line;
         DeviceState *dev;
 
@@ -382,10 +383,12 @@ static void aspeed_machine_init(MachineState *machine)
                           "max_ram", max_ram_size  - machine->ram_size);
     memory_region_add_subregion(&bmc->ram_container, machine->ram_size, &bmc->max_ram);
 
-    aspeed_board_init_flashes(&bmc->soc.fmc, bmc->fmc_model ?
-                              bmc->fmc_model : amc->fmc_model);
-    aspeed_board_init_flashes(&bmc->soc.spi[0], bmc->spi_model ?
-                              bmc->spi_model : amc->spi_model);
+    aspeed_board_init_flashes(&bmc->soc.fmc,
+                              bmc->fmc_model ? bmc->fmc_model : amc->fmc_model,
+                              0);
+    aspeed_board_init_flashes(&bmc->soc.spi[0],
+                              bmc->spi_model ? bmc->spi_model : amc->spi_model,
+                              bmc->soc.fmc.num_cs);
 
     /* Install first FMC flash content as a boot rom. */
     if (drive0) {
@@ -435,11 +438,13 @@ static void aspeed_machine_init(MachineState *machine)
     }
 
     for (i = 0; i < bmc->soc.sdhci.num_slots; i++) {
-        sdhci_attach_drive(&bmc->soc.sdhci.slots[i], drive_get_next(IF_SD));
+        sdhci_attach_drive(&bmc->soc.sdhci.slots[i],
+                           drive_get(IF_SD, 0, i));
     }
 
     if (bmc->soc.emmc.num_slots) {
-        sdhci_attach_drive(&bmc->soc.emmc.slots[0], drive_get_next(IF_SD));
+        sdhci_attach_drive(&bmc->soc.emmc.slots[0],
+                           drive_get(IF_SD, 0, bmc->soc.sdhci.num_slots));
     }
 
     arm_load_kernel(ARM_CPU(first_cpu), machine, &aspeed_board_binfo);
-- 
2.31.1