[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH v3 03/13] hw/arm/raspi: Extract the version from the board re

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v3 03/13] hw/arm/raspi: Extract the version from the board revision
Date: Thu, 13 Feb 2020 14:53:11 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1

On 2/13/20 2:40 PM, Peter Maydell wrote:
On Sat, 8 Feb 2020 at 16:57, Philippe Mathieu-Daudé <address@hidden> wrote:

The board revision encode the board version. Add a helper
to extract the version, and use it.

Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
  hw/arm/raspi.c | 31 +++++++++++++++++++++++++++----
  1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
index 818146fdbb..f285e2988f 100644
--- a/hw/arm/raspi.c
+++ b/hw/arm/raspi.c
@@ -16,6 +16,7 @@
  #include "qapi/error.h"
  #include "cpu.h"
  #include "hw/arm/bcm2836.h"
+#include "hw/registerfields.h"
  #include "qemu/error-report.h"
  #include "hw/boards.h"
  #include "hw/loader.h"
@@ -37,6 +38,28 @@ typedef struct RasPiState {
      MemoryRegion ram;
  } RasPiState;

+ * Board revision codes:
+ * www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/
+ */
+FIELD(REV_CODE, REVISION,           0, 4);
+FIELD(REV_CODE, TYPE,               4, 8);
+FIELD(REV_CODE, PROCESSOR,         12, 4);
+FIELD(REV_CODE, STYLE,             23, 1);
+static int board_processor_id(uint32_t board_rev)
+    assert(FIELD_EX32(board_rev, REV_CODE, STYLE)); /* Only new style */
+    return FIELD_EX32(board_rev, REV_CODE, PROCESSOR);
+static int board_version(uint32_t board_rev)
+    return board_processor_id(board_rev) + 1;

This uses the 'processor' field, which basically means the SoC
(0 for BCM2835, 1 for BCM2836, 2 for BCMM2837, 3 for BCM2711).
We use 'version' for a wider range of things in our code here:
  * do we need SMP setup?
  * which address does the firmware image go?
  * do we need to set up SMC vectors so no-op SMC works?
  * as well as "which SoC do we instantiate"?

We think of 'version' as basically "raspi 2 or 3?", but
according to the table in your url you can get a version of
the raspi 2b with a BCM2837 SoC, which confuses this idea.

Anyway, since what we have in this patch works OK for the set
of board models we support, I'm happy to leave the patch as-is,
but maybe worth checking and considering what in our code we
should really be making conditional on "actually the SoC type"
and what on something else...

Yes you are right, version = (2, 3) was too simple, I replaced the 'version' check by 'processor_id' in the series introducing the raspi4 (with other cleanups).
Eventually this file will only use the board_rev fields directly.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]