On Sat, Feb 8, 2020 at 5:57 PM Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
> When booting without device tree, the Linux kernels uses the $R1 > register to determine the machine type. The list of values is > registered at [1]. > > There are two entries for the Raspberry Pi: > > - https://www.arm.linux.org.uk/developer/machines/list.php?mid=3138 > name: MACH_TYPE_BCM2708 > value: 0xc42 (3138) > status: Active, not mainlined > date: 15 Oct 2010 > > - https://www.arm.linux.org.uk/developer/machines/list.php?mid=4828 > name: MACH_TYPE_BCM2835 > value: 4828 > status: Active, mainlined > date: 6 Dec 2013 > > QEMU always used the non-mainlined type MACH_TYPE_BCM2708. > The value 0xc43 is registered to 'MX51_GGC' (processor i.MX51), and > 0xc44 to 'Western Digital Sharespace NAS' (processor Marvell 88F5182). > > The Raspberry Pi foundation bootloader only sets the BCM2708 machine > type, see [2] or [3]: > > 133 9: > 134 mov r0, #0 > 135 ldr r1, =3138 @ BCM2708 machine id > 136 ldr r2, atags @ ATAGS > 137 bx r4 > > U-Boot only uses MACH_TYPE_BCM2708 (see [4]): > > 25 /* > 26 * 2835 is a SKU in a series for which the 2708 is the first or > primary SoC, > 27 * so 2708 has historically been used rather than a dedicated 2835 ID. > 28 * > 29 * We don't define a machine type for bcm2709/bcm2836 since the RPi > Foundation > 30 * chose to use someone else's previously registered machine ID (3139, > MX51_GGC) > 31 * rather than obtaining a valid ID:-/ > 32 * > 33 * For the bcm2837, hopefully a machine type is not needed, since > everything > 34 * is DT. > 35 */ > > While the definition MACH_BCM2709 with value 0xc43 was introduced in > a commit described "Add 2709 platform for Raspberry Pi 2" out of the > mainline Linux kernel, it does not seem used, and the platform is > introduced with Device Tree support anyway (see [5] and [6]). > > Remove the unused values (0xc43 introduced in commit 1df7d1f9303aef > "raspi: add raspberry pi 2 machine" and 0xc44 in commit bade58166f4 > "raspi: Raspberry Pi 3 support"), keeping only MACH_TYPE_BCM2708. > > [1] https://www.arm.linux.org.uk/developer/machines/ > [2] > https://github.com/raspberrypi/tools/blob/920c7ed2e/armstubs/armstub7.S#L135 > [3] > https://github.com/raspberrypi/tools/blob/49719d554/armstubs/armstub7.S#L64 > [4] > https://gitlab.denx.de/u-boot/u-boot/blob/v2015.04/include/configs/rpi-common.h#L18 > [5] > https://github.com/raspberrypi/linux/commit/d9fac63adac#diff-6722037d79570df5b392a49e0e006573R526 > [6] > http://lists.infradead.org/pipermail/linux-rpi-kernel/2015-February/001268.html > > Cc: Zoltán Baldaszti <bztem...@gmail.com> > Cc: Pekka Enberg <penb...@iki.fi> > Cc: Stephen Warren <swar...@nvidia.com> > Cc: Kshitij Soni <kshitij.s...@broadcom.com> > Cc: Michael Chan <michael.c...@broadcom.com> > Cc: Andrew Baumann <andrew.baum...@microsoft.com> > Reviewed-by: Alistair Francis <alistair.fran...@wdc.com> > Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> > Reviewed-by: Niek Linnenbank <nieklinnenb...@gmail.com> > --- > v3: Improved MACH_TYPE_BCM2708 comment (Zoltán) > --- > hw/arm/raspi.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c > index 3996f6c63a..f2ccabc662 100644 > --- a/hw/arm/raspi.c > +++ b/hw/arm/raspi.c > @@ -29,8 +29,8 @@ > #define FIRMWARE_ADDR_3 0x80000 /* Pi 3 loads kernel.img here by default > */ > #define SPINTABLE_ADDR 0xd8 /* Pi 3 bootloader spintable */ > > -/* Table of Linux board IDs for different Pi versions */ > -static const int raspi_boardid[] = {[1] = 0xc42, [2] = 0xc43, [3] = > 0xc44}; > +/* Registered machine type (matches RPi Foundation bootloader and U-Boot) > */ > +#define MACH_TYPE_BCM2708 3138 > > typedef struct RasPiState { > BCM283XState soc; > @@ -116,7 +116,7 @@ static void setup_boot(MachineState *machine, int > version, size_t ram_size) > static struct arm_boot_info binfo; > int r; > > - binfo.board_id = raspi_boardid[version]; > + binfo.board_id = MACH_TYPE_BCM2708; > binfo.ram_size = ram_size; > binfo.nb_cpus = machine->smp.cpus; > > -- > 2.21.1 > > -- Niek Linnenbank
