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Re: [PATCH] hw/misc/pfsoc: add fabric clocks to ioscb

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH] hw/misc/pfsoc: add fabric clocks to ioscb
Date: Thu, 10 Nov 2022 00:18:44 +0100
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.4.1

Hi Conor,

On 9/11/22 20:08, Conor Dooley wrote:
From: Conor Dooley <conor.dooley@microchip.com>

On PolarFire SoC, some peripherals (eg the PCI root port) are clocked by
"Clock Conditioning Circuitry" in the FPGA. The specific clock depends
on the FPGA bitstream & can be locked to one particular {D,P}LL - in the
Icicle Kit Reference Design v2022.09 or later this is/will be the case.

Linux v6.1+ will have a driver for this peripheral and devicetrees that
previously relied on "fixed-frequency" clock nodes have been switched
over to clock-controller nodes. The IOSCB region is represented in QEMU,
but the specific region of it that the CCCs occupy has not so v6.1-rcN
kernels fail to boot in QEMU.

Add the regions as unimplemented so that the status-quo in terms of boot
is maintained.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
The last line there is a white lie. v6.1-rcN has both v2022.09 and
v2022.10 reference design changes. This patch only accounts for the
v2022.09 changes. The FPGA design is a moving target and I am not
really sure how to handle that in QEMU. For v2022.10 a bunch of stuff
got changed, including the addresses that DDR lies at which I am not
sure how to handle yet.

That puts my todo list of broken things to:
- MMC (only direct kernel boot works), pre v2022.09 reference issue

How do you start without 'direct kernel boot'?

- PCI root port address, address changed in v2022.09 but from a cursory
   check, I didn't see any PCI support in the first place. It's connected
   to a FIC, so I think it can just be made into an unimplemented region.
- DDR address changes, 2022.10 issue. Looks like a straightforward
   change to hw/riscv/pfsoc.c but I don't think it'll be backwards
- hwrng breaks boot. Tipping away at this one, hopefully I'll have a fix
   for it soon. Need to implement the irq side of the mailbox for it.

I'll send some more patches as I work through them.

  hw/misc/mchp_pfsoc_ioscb.c         | 6 ++++++
  include/hw/misc/mchp_pfsoc_ioscb.h | 1 +
  2 files changed, 7 insertions(+)

diff --git a/hw/misc/mchp_pfsoc_ioscb.c b/hw/misc/mchp_pfsoc_ioscb.c
index f4fd55a0e5..f976e42f72 100644
--- a/hw/misc/mchp_pfsoc_ioscb.c
+++ b/hw/misc/mchp_pfsoc_ioscb.c
@@ -33,6 +33,7 @@
  #define IOSCB_WHOLE_REG_SIZE        0x10000000
  #define IOSCB_SUBMOD_REG_SIZE       0x1000
+#define IOSCB_CCC_REG_SIZE          0x2000000
   * There are many sub-modules in the IOSCB module.
@@ -45,6 +46,7 @@
  #define IOSCB_LANE23_BASE           0x06510000
  #define IOSCB_CTRL_BASE             0x07020000
  #define IOSCB_CFG_BASE              0x07080000
+#define IOSCB_CCC_BASE              0x08000000
  #define IOSCB_PLL_MSS_BASE          0x0E001000
  #define IOSCB_CFM_MSS_BASE          0x0E002000
  #define IOSCB_PLL_DDR_BASE          0x0E010000
@@ -168,6 +170,10 @@ static void mchp_pfsoc_ioscb_realize(DeviceState *dev, 
Error **errp)
                            "mchp.pfsoc.ioscb.cfg", IOSCB_SUBMOD_REG_SIZE);
      memory_region_add_subregion(&s->container, IOSCB_CFG_BASE, &s->cfg);
+ memory_region_init_io(&s->ccc, OBJECT(s), &mchp_pfsoc_dummy_ops, s,
+                          "mchp.pfsoc.ioscb.ccc", IOSCB_CCC_REG_SIZE);
+    memory_region_add_subregion(&s->container, IOSCB_CCC_BASE, &s->ccc);

Unrelated but using the TYPE_UNIMPLEMENTED_DEVICE would ease tracing all
these block accesses, as the block name would appear before the address/size. See for example aspeed_mmio_map_unimplemented();

Otherwise LGTM.



      memory_region_init_io(&s->pll_mss, OBJECT(s), &mchp_pfsoc_pll_ops, s,
                            "mchp.pfsoc.ioscb.pll_mss", IOSCB_SUBMOD_REG_SIZE);
      memory_region_add_subregion(&s->container, IOSCB_PLL_MSS_BASE, 
diff --git a/include/hw/misc/mchp_pfsoc_ioscb.h 
index 9235523e33..687b213742 100644
--- a/include/hw/misc/mchp_pfsoc_ioscb.h
+++ b/include/hw/misc/mchp_pfsoc_ioscb.h
@@ -30,6 +30,7 @@ typedef struct MchpPfSoCIoscbState {
      MemoryRegion lane23;
      MemoryRegion ctrl;
      MemoryRegion cfg;
+    MemoryRegion ccc;
      MemoryRegion pll_mss;
      MemoryRegion cfm_mss;
      MemoryRegion pll_ddr;

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